1 //===- InstCombineCompares.cpp --------------------------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file implements the visitICmp and visitFCmp functions.
11 //===----------------------------------------------------------------------===//
13 #include "InstCombineInternal.h"
14 #include "llvm/ADT/APSInt.h"
15 #include "llvm/ADT/SetVector.h"
16 #include "llvm/ADT/Statistic.h"
17 #include "llvm/Analysis/CaptureTracking.h"
18 #include "llvm/Analysis/CmpInstAnalysis.h"
19 #include "llvm/Analysis/ConstantFolding.h"
20 #include "llvm/Analysis/InstructionSimplify.h"
21 #include "llvm/Analysis/Utils/Local.h"
22 #include "llvm/Analysis/VectorUtils.h"
23 #include "llvm/IR/ConstantRange.h"
24 #include "llvm/IR/DataLayout.h"
25 #include "llvm/IR/InstrTypes.h"
26 #include "llvm/IR/IntrinsicInst.h"
27 #include "llvm/IR/PatternMatch.h"
28 #include "llvm/Support/KnownBits.h"
29 #include "llvm/Transforms/InstCombine/InstCombiner.h"
33 using namespace PatternMatch
;
35 #define DEBUG_TYPE "instcombine"
37 // How many times is a select replaced by one of its operands?
38 STATISTIC(NumSel
, "Number of select opts");
41 /// Compute Result = In1+In2, returning true if the result overflowed for this
43 static bool addWithOverflow(APInt
&Result
, const APInt
&In1
,
44 const APInt
&In2
, bool IsSigned
= false) {
47 Result
= In1
.sadd_ov(In2
, Overflow
);
49 Result
= In1
.uadd_ov(In2
, Overflow
);
54 /// Compute Result = In1-In2, returning true if the result overflowed for this
56 static bool subWithOverflow(APInt
&Result
, const APInt
&In1
,
57 const APInt
&In2
, bool IsSigned
= false) {
60 Result
= In1
.ssub_ov(In2
, Overflow
);
62 Result
= In1
.usub_ov(In2
, Overflow
);
67 /// Given an icmp instruction, return true if any use of this comparison is a
68 /// branch on sign bit comparison.
69 static bool hasBranchUse(ICmpInst
&I
) {
70 for (auto *U
: I
.users())
71 if (isa
<BranchInst
>(U
))
76 /// Returns true if the exploded icmp can be expressed as a signed comparison
77 /// to zero and updates the predicate accordingly.
78 /// The signedness of the comparison is preserved.
79 /// TODO: Refactor with decomposeBitTestICmp()?
80 static bool isSignTest(ICmpInst::Predicate
&Pred
, const APInt
&C
) {
81 if (!ICmpInst::isSigned(Pred
))
85 return ICmpInst::isRelational(Pred
);
88 if (Pred
== ICmpInst::ICMP_SLT
) {
89 Pred
= ICmpInst::ICMP_SLE
;
92 } else if (C
.isAllOnes()) {
93 if (Pred
== ICmpInst::ICMP_SGT
) {
94 Pred
= ICmpInst::ICMP_SGE
;
102 /// This is called when we see this pattern:
103 /// cmp pred (load (gep GV, ...)), cmpcst
104 /// where GV is a global variable with a constant initializer. Try to simplify
105 /// this into some simple computation that does not need the load. For example
106 /// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
108 /// If AndCst is non-null, then the loaded value is masked with that constant
109 /// before doing the comparison. This handles cases like "A[i]&4 == 0".
110 Instruction
*InstCombinerImpl::foldCmpLoadFromIndexedGlobal(
111 LoadInst
*LI
, GetElementPtrInst
*GEP
, GlobalVariable
*GV
, CmpInst
&ICI
,
112 ConstantInt
*AndCst
) {
113 if (LI
->isVolatile() || LI
->getType() != GEP
->getResultElementType() ||
114 GV
->getValueType() != GEP
->getSourceElementType() || !GV
->isConstant() ||
115 !GV
->hasDefinitiveInitializer())
118 Constant
*Init
= GV
->getInitializer();
119 if (!isa
<ConstantArray
>(Init
) && !isa
<ConstantDataArray
>(Init
))
122 uint64_t ArrayElementCount
= Init
->getType()->getArrayNumElements();
123 // Don't blow up on huge arrays.
124 if (ArrayElementCount
> MaxArraySizeForCombine
)
127 // There are many forms of this optimization we can handle, for now, just do
128 // the simple index into a single-dimensional array.
130 // Require: GEP GV, 0, i {{, constant indices}}
131 if (GEP
->getNumOperands() < 3 || !isa
<ConstantInt
>(GEP
->getOperand(1)) ||
132 !cast
<ConstantInt
>(GEP
->getOperand(1))->isZero() ||
133 isa
<Constant
>(GEP
->getOperand(2)))
136 // Check that indices after the variable are constants and in-range for the
137 // type they index. Collect the indices. This is typically for arrays of
139 SmallVector
<unsigned, 4> LaterIndices
;
141 Type
*EltTy
= Init
->getType()->getArrayElementType();
142 for (unsigned i
= 3, e
= GEP
->getNumOperands(); i
!= e
; ++i
) {
143 ConstantInt
*Idx
= dyn_cast
<ConstantInt
>(GEP
->getOperand(i
));
145 return nullptr; // Variable index.
147 uint64_t IdxVal
= Idx
->getZExtValue();
148 if ((unsigned)IdxVal
!= IdxVal
)
149 return nullptr; // Too large array index.
151 if (StructType
*STy
= dyn_cast
<StructType
>(EltTy
))
152 EltTy
= STy
->getElementType(IdxVal
);
153 else if (ArrayType
*ATy
= dyn_cast
<ArrayType
>(EltTy
)) {
154 if (IdxVal
>= ATy
->getNumElements())
156 EltTy
= ATy
->getElementType();
158 return nullptr; // Unknown type.
161 LaterIndices
.push_back(IdxVal
);
164 enum { Overdefined
= -3, Undefined
= -2 };
166 // Variables for our state machines.
168 // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
169 // "i == 47 | i == 87", where 47 is the first index the condition is true for,
170 // and 87 is the second (and last) index. FirstTrueElement is -2 when
171 // undefined, otherwise set to the first true element. SecondTrueElement is
172 // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
173 int FirstTrueElement
= Undefined
, SecondTrueElement
= Undefined
;
175 // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
176 // form "i != 47 & i != 87". Same state transitions as for true elements.
177 int FirstFalseElement
= Undefined
, SecondFalseElement
= Undefined
;
179 /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
180 /// define a state machine that triggers for ranges of values that the index
181 /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
182 /// This is -2 when undefined, -3 when overdefined, and otherwise the last
183 /// index in the range (inclusive). We use -2 for undefined here because we
184 /// use relative comparisons and don't want 0-1 to match -1.
185 int TrueRangeEnd
= Undefined
, FalseRangeEnd
= Undefined
;
187 // MagicBitvector - This is a magic bitvector where we set a bit if the
188 // comparison is true for element 'i'. If there are 64 elements or less in
189 // the array, this will fully represent all the comparison results.
190 uint64_t MagicBitvector
= 0;
192 // Scan the array and see if one of our patterns matches.
193 Constant
*CompareRHS
= cast
<Constant
>(ICI
.getOperand(1));
194 for (unsigned i
= 0, e
= ArrayElementCount
; i
!= e
; ++i
) {
195 Constant
*Elt
= Init
->getAggregateElement(i
);
199 // If this is indexing an array of structures, get the structure element.
200 if (!LaterIndices
.empty()) {
201 Elt
= ConstantFoldExtractValueInstruction(Elt
, LaterIndices
);
206 // If the element is masked, handle it.
208 Elt
= ConstantFoldBinaryOpOperands(Instruction::And
, Elt
, AndCst
, DL
);
213 // Find out if the comparison would be true or false for the i'th element.
214 Constant
*C
= ConstantFoldCompareInstOperands(ICI
.getPredicate(), Elt
,
215 CompareRHS
, DL
, &TLI
);
219 // If the result is undef for this element, ignore it.
220 if (isa
<UndefValue
>(C
)) {
221 // Extend range state machines to cover this element in case there is an
222 // undef in the middle of the range.
223 if (TrueRangeEnd
== (int)i
- 1)
225 if (FalseRangeEnd
== (int)i
- 1)
230 // If we can't compute the result for any of the elements, we have to give
231 // up evaluating the entire conditional.
232 if (!isa
<ConstantInt
>(C
))
235 // Otherwise, we know if the comparison is true or false for this element,
236 // update our state machines.
237 bool IsTrueForElt
= !cast
<ConstantInt
>(C
)->isZero();
239 // State machine for single/double/range index comparison.
241 // Update the TrueElement state machine.
242 if (FirstTrueElement
== Undefined
)
243 FirstTrueElement
= TrueRangeEnd
= i
; // First true element.
245 // Update double-compare state machine.
246 if (SecondTrueElement
== Undefined
)
247 SecondTrueElement
= i
;
249 SecondTrueElement
= Overdefined
;
251 // Update range state machine.
252 if (TrueRangeEnd
== (int)i
- 1)
255 TrueRangeEnd
= Overdefined
;
258 // Update the FalseElement state machine.
259 if (FirstFalseElement
== Undefined
)
260 FirstFalseElement
= FalseRangeEnd
= i
; // First false element.
262 // Update double-compare state machine.
263 if (SecondFalseElement
== Undefined
)
264 SecondFalseElement
= i
;
266 SecondFalseElement
= Overdefined
;
268 // Update range state machine.
269 if (FalseRangeEnd
== (int)i
- 1)
272 FalseRangeEnd
= Overdefined
;
276 // If this element is in range, update our magic bitvector.
277 if (i
< 64 && IsTrueForElt
)
278 MagicBitvector
|= 1ULL << i
;
280 // If all of our states become overdefined, bail out early. Since the
281 // predicate is expensive, only check it every 8 elements. This is only
282 // really useful for really huge arrays.
283 if ((i
& 8) == 0 && i
>= 64 && SecondTrueElement
== Overdefined
&&
284 SecondFalseElement
== Overdefined
&& TrueRangeEnd
== Overdefined
&&
285 FalseRangeEnd
== Overdefined
)
289 // Now that we've scanned the entire array, emit our new comparison(s). We
290 // order the state machines in complexity of the generated code.
291 Value
*Idx
= GEP
->getOperand(2);
293 // If the index is larger than the pointer offset size of the target, truncate
294 // the index down like the GEP would do implicitly. We don't have to do this
295 // for an inbounds GEP because the index can't be out of range.
296 if (!GEP
->isInBounds()) {
297 Type
*PtrIdxTy
= DL
.getIndexType(GEP
->getType());
298 unsigned OffsetSize
= PtrIdxTy
->getIntegerBitWidth();
299 if (Idx
->getType()->getPrimitiveSizeInBits().getFixedValue() > OffsetSize
)
300 Idx
= Builder
.CreateTrunc(Idx
, PtrIdxTy
);
303 // If inbounds keyword is not present, Idx * ElementSize can overflow.
304 // Let's assume that ElementSize is 2 and the wanted value is at offset 0.
305 // Then, there are two possible values for Idx to match offset 0:
306 // 0x00..00, 0x80..00.
307 // Emitting 'icmp eq Idx, 0' isn't correct in this case because the
308 // comparison is false if Idx was 0x80..00.
309 // We need to erase the highest countTrailingZeros(ElementSize) bits of Idx.
310 unsigned ElementSize
=
311 DL
.getTypeAllocSize(Init
->getType()->getArrayElementType());
312 auto MaskIdx
= [&](Value
*Idx
) {
313 if (!GEP
->isInBounds() && llvm::countr_zero(ElementSize
) != 0) {
314 Value
*Mask
= Constant::getAllOnesValue(Idx
->getType());
315 Mask
= Builder
.CreateLShr(Mask
, llvm::countr_zero(ElementSize
));
316 Idx
= Builder
.CreateAnd(Idx
, Mask
);
321 // If the comparison is only true for one or two elements, emit direct
323 if (SecondTrueElement
!= Overdefined
) {
325 // None true -> false.
326 if (FirstTrueElement
== Undefined
)
327 return replaceInstUsesWith(ICI
, Builder
.getFalse());
329 Value
*FirstTrueIdx
= ConstantInt::get(Idx
->getType(), FirstTrueElement
);
331 // True for one element -> 'i == 47'.
332 if (SecondTrueElement
== Undefined
)
333 return new ICmpInst(ICmpInst::ICMP_EQ
, Idx
, FirstTrueIdx
);
335 // True for two elements -> 'i == 47 | i == 72'.
336 Value
*C1
= Builder
.CreateICmpEQ(Idx
, FirstTrueIdx
);
337 Value
*SecondTrueIdx
= ConstantInt::get(Idx
->getType(), SecondTrueElement
);
338 Value
*C2
= Builder
.CreateICmpEQ(Idx
, SecondTrueIdx
);
339 return BinaryOperator::CreateOr(C1
, C2
);
342 // If the comparison is only false for one or two elements, emit direct
344 if (SecondFalseElement
!= Overdefined
) {
346 // None false -> true.
347 if (FirstFalseElement
== Undefined
)
348 return replaceInstUsesWith(ICI
, Builder
.getTrue());
350 Value
*FirstFalseIdx
= ConstantInt::get(Idx
->getType(), FirstFalseElement
);
352 // False for one element -> 'i != 47'.
353 if (SecondFalseElement
== Undefined
)
354 return new ICmpInst(ICmpInst::ICMP_NE
, Idx
, FirstFalseIdx
);
356 // False for two elements -> 'i != 47 & i != 72'.
357 Value
*C1
= Builder
.CreateICmpNE(Idx
, FirstFalseIdx
);
358 Value
*SecondFalseIdx
=
359 ConstantInt::get(Idx
->getType(), SecondFalseElement
);
360 Value
*C2
= Builder
.CreateICmpNE(Idx
, SecondFalseIdx
);
361 return BinaryOperator::CreateAnd(C1
, C2
);
364 // If the comparison can be replaced with a range comparison for the elements
365 // where it is true, emit the range check.
366 if (TrueRangeEnd
!= Overdefined
) {
367 assert(TrueRangeEnd
!= FirstTrueElement
&& "Should emit single compare");
370 // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
371 if (FirstTrueElement
) {
372 Value
*Offs
= ConstantInt::get(Idx
->getType(), -FirstTrueElement
);
373 Idx
= Builder
.CreateAdd(Idx
, Offs
);
377 ConstantInt::get(Idx
->getType(), TrueRangeEnd
- FirstTrueElement
+ 1);
378 return new ICmpInst(ICmpInst::ICMP_ULT
, Idx
, End
);
381 // False range check.
382 if (FalseRangeEnd
!= Overdefined
) {
383 assert(FalseRangeEnd
!= FirstFalseElement
&& "Should emit single compare");
385 // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
386 if (FirstFalseElement
) {
387 Value
*Offs
= ConstantInt::get(Idx
->getType(), -FirstFalseElement
);
388 Idx
= Builder
.CreateAdd(Idx
, Offs
);
392 ConstantInt::get(Idx
->getType(), FalseRangeEnd
- FirstFalseElement
);
393 return new ICmpInst(ICmpInst::ICMP_UGT
, Idx
, End
);
396 // If a magic bitvector captures the entire comparison state
397 // of this load, replace it with computation that does:
398 // ((magic_cst >> i) & 1) != 0
402 // Look for an appropriate type:
403 // - The type of Idx if the magic fits
404 // - The smallest fitting legal type
405 if (ArrayElementCount
<= Idx
->getType()->getIntegerBitWidth())
408 Ty
= DL
.getSmallestLegalIntType(Init
->getContext(), ArrayElementCount
);
412 Value
*V
= Builder
.CreateIntCast(Idx
, Ty
, false);
413 V
= Builder
.CreateLShr(ConstantInt::get(Ty
, MagicBitvector
), V
);
414 V
= Builder
.CreateAnd(ConstantInt::get(Ty
, 1), V
);
415 return new ICmpInst(ICmpInst::ICMP_NE
, V
, ConstantInt::get(Ty
, 0));
422 /// Returns true if we can rewrite Start as a GEP with pointer Base
423 /// and some integer offset. The nodes that need to be re-written
424 /// for this transformation will be added to Explored.
425 static bool canRewriteGEPAsOffset(Value
*Start
, Value
*Base
, GEPNoWrapFlags
&NW
,
426 const DataLayout
&DL
,
427 SetVector
<Value
*> &Explored
) {
428 SmallVector
<Value
*, 16> WorkList(1, Start
);
429 Explored
.insert(Base
);
431 // The following traversal gives us an order which can be used
432 // when doing the final transformation. Since in the final
433 // transformation we create the PHI replacement instructions first,
434 // we don't have to get them in any particular order.
436 // However, for other instructions we will have to traverse the
437 // operands of an instruction first, which means that we have to
438 // do a post-order traversal.
439 while (!WorkList
.empty()) {
440 SetVector
<PHINode
*> PHIs
;
442 while (!WorkList
.empty()) {
443 if (Explored
.size() >= 100)
446 Value
*V
= WorkList
.back();
448 if (Explored
.contains(V
)) {
453 if (!isa
<GetElementPtrInst
>(V
) && !isa
<PHINode
>(V
))
454 // We've found some value that we can't explore which is different from
455 // the base. Therefore we can't do this transformation.
458 if (auto *GEP
= dyn_cast
<GEPOperator
>(V
)) {
459 // Only allow inbounds GEPs with at most one variable offset.
460 auto IsNonConst
= [](Value
*V
) { return !isa
<ConstantInt
>(V
); };
461 if (!GEP
->isInBounds() || count_if(GEP
->indices(), IsNonConst
) > 1)
464 NW
= NW
.intersectForOffsetAdd(GEP
->getNoWrapFlags());
465 if (!Explored
.contains(GEP
->getOperand(0)))
466 WorkList
.push_back(GEP
->getOperand(0));
469 if (WorkList
.back() == V
) {
471 // We've finished visiting this node, mark it as such.
475 if (auto *PN
= dyn_cast
<PHINode
>(V
)) {
476 // We cannot transform PHIs on unsplittable basic blocks.
477 if (isa
<CatchSwitchInst
>(PN
->getParent()->getTerminator()))
484 // Explore the PHI nodes further.
485 for (auto *PN
: PHIs
)
486 for (Value
*Op
: PN
->incoming_values())
487 if (!Explored
.contains(Op
))
488 WorkList
.push_back(Op
);
491 // Make sure that we can do this. Since we can't insert GEPs in a basic
492 // block before a PHI node, we can't easily do this transformation if
493 // we have PHI node users of transformed instructions.
494 for (Value
*Val
: Explored
) {
495 for (Value
*Use
: Val
->uses()) {
497 auto *PHI
= dyn_cast
<PHINode
>(Use
);
498 auto *Inst
= dyn_cast
<Instruction
>(Val
);
500 if (Inst
== Base
|| Inst
== PHI
|| !Inst
|| !PHI
||
501 !Explored
.contains(PHI
))
504 if (PHI
->getParent() == Inst
->getParent())
511 // Sets the appropriate insert point on Builder where we can add
512 // a replacement Instruction for V (if that is possible).
513 static void setInsertionPoint(IRBuilder
<> &Builder
, Value
*V
,
514 bool Before
= true) {
515 if (auto *PHI
= dyn_cast
<PHINode
>(V
)) {
516 BasicBlock
*Parent
= PHI
->getParent();
517 Builder
.SetInsertPoint(Parent
, Parent
->getFirstInsertionPt());
520 if (auto *I
= dyn_cast
<Instruction
>(V
)) {
522 I
= &*std::next(I
->getIterator());
523 Builder
.SetInsertPoint(I
);
526 if (auto *A
= dyn_cast
<Argument
>(V
)) {
527 // Set the insertion point in the entry block.
528 BasicBlock
&Entry
= A
->getParent()->getEntryBlock();
529 Builder
.SetInsertPoint(&Entry
, Entry
.getFirstInsertionPt());
532 // Otherwise, this is a constant and we don't need to set a new
534 assert(isa
<Constant
>(V
) && "Setting insertion point for unknown value!");
537 /// Returns a re-written value of Start as an indexed GEP using Base as a
539 static Value
*rewriteGEPAsOffset(Value
*Start
, Value
*Base
, GEPNoWrapFlags NW
,
540 const DataLayout
&DL
,
541 SetVector
<Value
*> &Explored
,
543 // Perform all the substitutions. This is a bit tricky because we can
544 // have cycles in our use-def chains.
545 // 1. Create the PHI nodes without any incoming values.
546 // 2. Create all the other values.
547 // 3. Add the edges for the PHI nodes.
548 // 4. Emit GEPs to get the original pointers.
549 // 5. Remove the original instructions.
550 Type
*IndexType
= IntegerType::get(
551 Base
->getContext(), DL
.getIndexTypeSizeInBits(Start
->getType()));
553 DenseMap
<Value
*, Value
*> NewInsts
;
554 NewInsts
[Base
] = ConstantInt::getNullValue(IndexType
);
556 // Create the new PHI nodes, without adding any incoming values.
557 for (Value
*Val
: Explored
) {
560 // Create empty phi nodes. This avoids cyclic dependencies when creating
561 // the remaining instructions.
562 if (auto *PHI
= dyn_cast
<PHINode
>(Val
))
564 PHINode::Create(IndexType
, PHI
->getNumIncomingValues(),
565 PHI
->getName() + ".idx", PHI
->getIterator());
567 IRBuilder
<> Builder(Base
->getContext());
569 // Create all the other instructions.
570 for (Value
*Val
: Explored
) {
571 if (NewInsts
.contains(Val
))
574 if (auto *GEP
= dyn_cast
<GEPOperator
>(Val
)) {
575 setInsertionPoint(Builder
, GEP
);
576 Value
*Op
= NewInsts
[GEP
->getOperand(0)];
577 Value
*OffsetV
= emitGEPOffset(&Builder
, DL
, GEP
);
578 if (isa
<ConstantInt
>(Op
) && cast
<ConstantInt
>(Op
)->isZero())
579 NewInsts
[GEP
] = OffsetV
;
581 NewInsts
[GEP
] = Builder
.CreateAdd(
582 Op
, OffsetV
, GEP
->getOperand(0)->getName() + ".add",
583 /*NUW=*/NW
.hasNoUnsignedWrap(),
584 /*NSW=*/NW
.hasNoUnsignedSignedWrap());
587 if (isa
<PHINode
>(Val
))
590 llvm_unreachable("Unexpected instruction type");
593 // Add the incoming values to the PHI nodes.
594 for (Value
*Val
: Explored
) {
597 // All the instructions have been created, we can now add edges to the
599 if (auto *PHI
= dyn_cast
<PHINode
>(Val
)) {
600 PHINode
*NewPhi
= static_cast<PHINode
*>(NewInsts
[PHI
]);
601 for (unsigned I
= 0, E
= PHI
->getNumIncomingValues(); I
< E
; ++I
) {
602 Value
*NewIncoming
= PHI
->getIncomingValue(I
);
604 auto It
= NewInsts
.find(NewIncoming
);
605 if (It
!= NewInsts
.end())
606 NewIncoming
= It
->second
;
608 NewPhi
->addIncoming(NewIncoming
, PHI
->getIncomingBlock(I
));
613 for (Value
*Val
: Explored
) {
617 setInsertionPoint(Builder
, Val
, false);
618 // Create GEP for external users.
619 Value
*NewVal
= Builder
.CreateGEP(Builder
.getInt8Ty(), Base
, NewInsts
[Val
],
620 Val
->getName() + ".ptr", NW
);
621 IC
.replaceInstUsesWith(*cast
<Instruction
>(Val
), NewVal
);
622 // Add old instruction to worklist for DCE. We don't directly remove it
623 // here because the original compare is one of the users.
624 IC
.addToWorklist(cast
<Instruction
>(Val
));
627 return NewInsts
[Start
];
630 /// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant.
631 /// We can look through PHIs, GEPs and casts in order to determine a common base
632 /// between GEPLHS and RHS.
633 static Instruction
*transformToIndexedCompare(GEPOperator
*GEPLHS
, Value
*RHS
,
635 const DataLayout
&DL
,
637 // FIXME: Support vector of pointers.
638 if (GEPLHS
->getType()->isVectorTy())
641 if (!GEPLHS
->hasAllConstantIndices())
644 APInt
Offset(DL
.getIndexTypeSizeInBits(GEPLHS
->getType()), 0);
646 GEPLHS
->stripAndAccumulateConstantOffsets(DL
, Offset
,
647 /*AllowNonInbounds*/ false);
649 // Bail if we looked through addrspacecast.
650 if (PtrBase
->getType() != GEPLHS
->getType())
653 // The set of nodes that will take part in this transformation.
654 SetVector
<Value
*> Nodes
;
655 GEPNoWrapFlags NW
= GEPLHS
->getNoWrapFlags();
656 if (!canRewriteGEPAsOffset(RHS
, PtrBase
, NW
, DL
, Nodes
))
659 // We know we can re-write this as
660 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)
661 // Since we've only looked through inbouds GEPs we know that we
662 // can't have overflow on either side. We can therefore re-write
664 // OFFSET1 cmp OFFSET2
665 Value
*NewRHS
= rewriteGEPAsOffset(RHS
, PtrBase
, NW
, DL
, Nodes
, IC
);
667 // RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written
668 // GEP having PtrBase as the pointer base, and has returned in NewRHS the
669 // offset. Since Index is the offset of LHS to the base pointer, we will now
670 // compare the offsets instead of comparing the pointers.
671 return new ICmpInst(ICmpInst::getSignedPredicate(Cond
),
672 IC
.Builder
.getInt(Offset
), NewRHS
);
675 /// Fold comparisons between a GEP instruction and something else. At this point
676 /// we know that the GEP is on the LHS of the comparison.
677 Instruction
*InstCombinerImpl::foldGEPICmp(GEPOperator
*GEPLHS
, Value
*RHS
,
678 CmpPredicate Cond
, Instruction
&I
) {
679 // Don't transform signed compares of GEPs into index compares. Even if the
680 // GEP is inbounds, the final add of the base pointer can have signed overflow
681 // and would change the result of the icmp.
682 // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
683 // the maximum signed value for the pointer type.
684 if (ICmpInst::isSigned(Cond
))
687 // Look through bitcasts and addrspacecasts. We do not however want to remove
689 if (!isa
<GetElementPtrInst
>(RHS
))
690 RHS
= RHS
->stripPointerCasts();
692 auto CanFold
= [Cond
](GEPNoWrapFlags NW
) {
693 if (ICmpInst::isEquality(Cond
))
696 // Unsigned predicates can be folded if the GEPs have *any* nowrap flags.
697 assert(ICmpInst::isUnsigned(Cond
));
698 return NW
!= GEPNoWrapFlags::none();
701 auto NewICmp
= [Cond
](GEPNoWrapFlags NW
, Value
*Op1
, Value
*Op2
) {
702 if (!NW
.hasNoUnsignedWrap()) {
703 // Convert signed to unsigned comparison.
704 return new ICmpInst(ICmpInst::getSignedPredicate(Cond
), Op1
, Op2
);
707 auto *I
= new ICmpInst(Cond
, Op1
, Op2
);
708 I
->setSameSign(NW
.hasNoUnsignedSignedWrap());
712 Value
*PtrBase
= GEPLHS
->getOperand(0);
713 if (PtrBase
== RHS
&& CanFold(GEPLHS
->getNoWrapFlags())) {
714 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
715 Value
*Offset
= EmitGEPOffset(GEPLHS
);
716 return NewICmp(GEPLHS
->getNoWrapFlags(), Offset
,
717 Constant::getNullValue(Offset
->getType()));
720 if (GEPLHS
->isInBounds() && ICmpInst::isEquality(Cond
) &&
721 isa
<Constant
>(RHS
) && cast
<Constant
>(RHS
)->isNullValue() &&
722 !NullPointerIsDefined(I
.getFunction(),
723 RHS
->getType()->getPointerAddressSpace())) {
724 // For most address spaces, an allocation can't be placed at null, but null
725 // itself is treated as a 0 size allocation in the in bounds rules. Thus,
726 // the only valid inbounds address derived from null, is null itself.
727 // Thus, we have four cases to consider:
728 // 1) Base == nullptr, Offset == 0 -> inbounds, null
729 // 2) Base == nullptr, Offset != 0 -> poison as the result is out of bounds
730 // 3) Base != nullptr, Offset == (-base) -> poison (crossing allocations)
731 // 4) Base != nullptr, Offset != (-base) -> nonnull (and possibly poison)
733 // (Note if we're indexing a type of size 0, that simply collapses into one
734 // of the buckets above.)
736 // In general, we're allowed to make values less poison (i.e. remove
737 // sources of full UB), so in this case, we just select between the two
738 // non-poison cases (1 and 4 above).
740 // For vectors, we apply the same reasoning on a per-lane basis.
741 auto *Base
= GEPLHS
->getPointerOperand();
742 if (GEPLHS
->getType()->isVectorTy() && Base
->getType()->isPointerTy()) {
743 auto EC
= cast
<VectorType
>(GEPLHS
->getType())->getElementCount();
744 Base
= Builder
.CreateVectorSplat(EC
, Base
);
746 return new ICmpInst(Cond
, Base
,
747 ConstantExpr::getPointerBitCastOrAddrSpaceCast(
748 cast
<Constant
>(RHS
), Base
->getType()));
749 } else if (GEPOperator
*GEPRHS
= dyn_cast
<GEPOperator
>(RHS
)) {
750 GEPNoWrapFlags NW
= GEPLHS
->getNoWrapFlags() & GEPRHS
->getNoWrapFlags();
752 // If the base pointers are different, but the indices are the same, just
753 // compare the base pointer.
754 if (PtrBase
!= GEPRHS
->getOperand(0)) {
755 bool IndicesTheSame
=
756 GEPLHS
->getNumOperands() == GEPRHS
->getNumOperands() &&
757 GEPLHS
->getPointerOperand()->getType() ==
758 GEPRHS
->getPointerOperand()->getType() &&
759 GEPLHS
->getSourceElementType() == GEPRHS
->getSourceElementType();
761 for (unsigned i
= 1, e
= GEPLHS
->getNumOperands(); i
!= e
; ++i
)
762 if (GEPLHS
->getOperand(i
) != GEPRHS
->getOperand(i
)) {
763 IndicesTheSame
= false;
767 // If all indices are the same, just compare the base pointers.
768 Type
*BaseType
= GEPLHS
->getOperand(0)->getType();
769 if (IndicesTheSame
&&
770 CmpInst::makeCmpResultType(BaseType
) == I
.getType() && CanFold(NW
))
771 return new ICmpInst(Cond
, GEPLHS
->getOperand(0), GEPRHS
->getOperand(0));
773 // If we're comparing GEPs with two base pointers that only differ in type
774 // and both GEPs have only constant indices or just one use, then fold
775 // the compare with the adjusted indices.
776 // FIXME: Support vector of pointers.
777 if (GEPLHS
->isInBounds() && GEPRHS
->isInBounds() &&
778 (GEPLHS
->hasAllConstantIndices() || GEPLHS
->hasOneUse()) &&
779 (GEPRHS
->hasAllConstantIndices() || GEPRHS
->hasOneUse()) &&
780 PtrBase
->stripPointerCasts() ==
781 GEPRHS
->getOperand(0)->stripPointerCasts() &&
782 !GEPLHS
->getType()->isVectorTy()) {
783 Value
*LOffset
= EmitGEPOffset(GEPLHS
);
784 Value
*ROffset
= EmitGEPOffset(GEPRHS
);
786 // If we looked through an addrspacecast between different sized address
787 // spaces, the LHS and RHS pointers are different sized
788 // integers. Truncate to the smaller one.
789 Type
*LHSIndexTy
= LOffset
->getType();
790 Type
*RHSIndexTy
= ROffset
->getType();
791 if (LHSIndexTy
!= RHSIndexTy
) {
792 if (LHSIndexTy
->getPrimitiveSizeInBits().getFixedValue() <
793 RHSIndexTy
->getPrimitiveSizeInBits().getFixedValue()) {
794 ROffset
= Builder
.CreateTrunc(ROffset
, LHSIndexTy
);
796 LOffset
= Builder
.CreateTrunc(LOffset
, RHSIndexTy
);
799 Value
*Cmp
= Builder
.CreateICmp(ICmpInst::getSignedPredicate(Cond
),
801 return replaceInstUsesWith(I
, Cmp
);
804 // Otherwise, the base pointers are different and the indices are
805 // different. Try convert this to an indexed compare by looking through
807 return transformToIndexedCompare(GEPLHS
, RHS
, Cond
, DL
, *this);
810 if (GEPLHS
->getNumOperands() == GEPRHS
->getNumOperands() &&
811 GEPLHS
->getSourceElementType() == GEPRHS
->getSourceElementType()) {
812 // If the GEPs only differ by one index, compare it.
813 unsigned NumDifferences
= 0; // Keep track of # differences.
814 unsigned DiffOperand
= 0; // The operand that differs.
815 for (unsigned i
= 1, e
= GEPRHS
->getNumOperands(); i
!= e
; ++i
)
816 if (GEPLHS
->getOperand(i
) != GEPRHS
->getOperand(i
)) {
817 Type
*LHSType
= GEPLHS
->getOperand(i
)->getType();
818 Type
*RHSType
= GEPRHS
->getOperand(i
)->getType();
819 // FIXME: Better support for vector of pointers.
820 if (LHSType
->getPrimitiveSizeInBits() !=
821 RHSType
->getPrimitiveSizeInBits() ||
822 (GEPLHS
->getType()->isVectorTy() &&
823 (!LHSType
->isVectorTy() || !RHSType
->isVectorTy()))) {
824 // Irreconcilable differences.
829 if (NumDifferences
++) break;
833 if (NumDifferences
== 0) // SAME GEP?
834 return replaceInstUsesWith(I
, // No comparison is needed here.
835 ConstantInt::get(I
.getType(), ICmpInst::isTrueWhenEqual(Cond
)));
837 else if (NumDifferences
== 1 && CanFold(NW
)) {
838 Value
*LHSV
= GEPLHS
->getOperand(DiffOperand
);
839 Value
*RHSV
= GEPRHS
->getOperand(DiffOperand
);
840 return NewICmp(NW
, LHSV
, RHSV
);
845 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
846 Value
*L
= EmitGEPOffset(GEPLHS
, /*RewriteGEP=*/true);
847 Value
*R
= EmitGEPOffset(GEPRHS
, /*RewriteGEP=*/true);
848 return NewICmp(NW
, L
, R
);
852 // Try convert this to an indexed compare by looking through PHIs/casts as a
854 return transformToIndexedCompare(GEPLHS
, RHS
, Cond
, DL
, *this);
857 bool InstCombinerImpl::foldAllocaCmp(AllocaInst
*Alloca
) {
858 // It would be tempting to fold away comparisons between allocas and any
859 // pointer not based on that alloca (e.g. an argument). However, even
860 // though such pointers cannot alias, they can still compare equal.
862 // But LLVM doesn't specify where allocas get their memory, so if the alloca
863 // doesn't escape we can argue that it's impossible to guess its value, and we
864 // can therefore act as if any such guesses are wrong.
866 // However, we need to ensure that this folding is consistent: We can't fold
867 // one comparison to false, and then leave a different comparison against the
868 // same value alone (as it might evaluate to true at runtime, leading to a
869 // contradiction). As such, this code ensures that all comparisons are folded
870 // at the same time, and there are no other escapes.
872 struct CmpCaptureTracker
: public CaptureTracker
{
874 bool Captured
= false;
875 /// The value of the map is a bit mask of which icmp operands the alloca is
877 SmallMapVector
<ICmpInst
*, unsigned, 4> ICmps
;
879 CmpCaptureTracker(AllocaInst
*Alloca
) : Alloca(Alloca
) {}
881 void tooManyUses() override
{ Captured
= true; }
883 bool captured(const Use
*U
) override
{
884 auto *ICmp
= dyn_cast
<ICmpInst
>(U
->getUser());
885 // We need to check that U is based *only* on the alloca, and doesn't
886 // have other contributions from a select/phi operand.
887 // TODO: We could check whether getUnderlyingObjects() reduces to one
888 // object, which would allow looking through phi nodes.
889 if (ICmp
&& ICmp
->isEquality() && getUnderlyingObject(*U
) == Alloca
) {
890 // Collect equality icmps of the alloca, and don't treat them as
892 ICmps
[ICmp
] |= 1u << U
->getOperandNo();
901 CmpCaptureTracker
Tracker(Alloca
);
902 PointerMayBeCaptured(Alloca
, &Tracker
);
903 if (Tracker
.Captured
)
906 bool Changed
= false;
907 for (auto [ICmp
, Operands
] : Tracker
.ICmps
) {
911 // The alloca is only used in one icmp operand. Assume that the
912 // equality is false.
913 auto *Res
= ConstantInt::get(
914 ICmp
->getType(), ICmp
->getPredicate() == ICmpInst::ICMP_NE
);
915 replaceInstUsesWith(*ICmp
, Res
);
916 eraseInstFromFunction(*ICmp
);
921 // Both icmp operands are based on the alloca, so this is comparing
922 // pointer offsets, without leaking any information about the address
923 // of the alloca. Ignore such comparisons.
926 llvm_unreachable("Cannot happen");
933 /// Fold "icmp pred (X+C), X".
934 Instruction
*InstCombinerImpl::foldICmpAddOpConst(Value
*X
, const APInt
&C
,
936 // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
937 // so the values can never be equal. Similarly for all other "or equals"
939 assert(!!C
&& "C should not be zero!");
941 // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255
942 // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
943 // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
944 if (Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_ULE
) {
945 Constant
*R
= ConstantInt::get(X
->getType(),
946 APInt::getMaxValue(C
.getBitWidth()) - C
);
947 return new ICmpInst(ICmpInst::ICMP_UGT
, X
, R
);
950 // (X+1) >u X --> X <u (0-1) --> X != 255
951 // (X+2) >u X --> X <u (0-2) --> X <u 254
952 // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
953 if (Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_UGE
)
954 return new ICmpInst(ICmpInst::ICMP_ULT
, X
,
955 ConstantInt::get(X
->getType(), -C
));
957 APInt SMax
= APInt::getSignedMaxValue(C
.getBitWidth());
959 // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
960 // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
961 // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
962 // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
963 // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
964 // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
965 if (Pred
== ICmpInst::ICMP_SLT
|| Pred
== ICmpInst::ICMP_SLE
)
966 return new ICmpInst(ICmpInst::ICMP_SGT
, X
,
967 ConstantInt::get(X
->getType(), SMax
- C
));
969 // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
970 // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
971 // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
972 // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
973 // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
974 // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
976 assert(Pred
== ICmpInst::ICMP_SGT
|| Pred
== ICmpInst::ICMP_SGE
);
977 return new ICmpInst(ICmpInst::ICMP_SLT
, X
,
978 ConstantInt::get(X
->getType(), SMax
- (C
- 1)));
981 /// Handle "(icmp eq/ne (ashr/lshr AP2, A), AP1)" ->
982 /// (icmp eq/ne A, Log2(AP2/AP1)) ->
983 /// (icmp eq/ne A, Log2(AP2) - Log2(AP1)).
984 Instruction
*InstCombinerImpl::foldICmpShrConstConst(ICmpInst
&I
, Value
*A
,
987 assert(I
.isEquality() && "Cannot fold icmp gt/lt");
989 auto getICmp
= [&I
](CmpInst::Predicate Pred
, Value
*LHS
, Value
*RHS
) {
990 if (I
.getPredicate() == I
.ICMP_NE
)
991 Pred
= CmpInst::getInversePredicate(Pred
);
992 return new ICmpInst(Pred
, LHS
, RHS
);
995 // Don't bother doing any work for cases which InstSimplify handles.
999 bool IsAShr
= isa
<AShrOperator
>(I
.getOperand(0));
1001 if (AP2
.isAllOnes())
1003 if (AP2
.isNegative() != AP1
.isNegative())
1010 // 'A' must be large enough to shift out the highest set bit.
1011 return getICmp(I
.ICMP_UGT
, A
,
1012 ConstantInt::get(A
->getType(), AP2
.logBase2()));
1015 return getICmp(I
.ICMP_EQ
, A
, ConstantInt::getNullValue(A
->getType()));
1018 if (IsAShr
&& AP1
.isNegative())
1019 Shift
= AP1
.countl_one() - AP2
.countl_one();
1021 Shift
= AP1
.countl_zero() - AP2
.countl_zero();
1024 if (IsAShr
&& AP1
== AP2
.ashr(Shift
)) {
1025 // There are multiple solutions if we are comparing against -1 and the LHS
1026 // of the ashr is not a power of two.
1027 if (AP1
.isAllOnes() && !AP2
.isPowerOf2())
1028 return getICmp(I
.ICMP_UGE
, A
, ConstantInt::get(A
->getType(), Shift
));
1029 return getICmp(I
.ICMP_EQ
, A
, ConstantInt::get(A
->getType(), Shift
));
1030 } else if (AP1
== AP2
.lshr(Shift
)) {
1031 return getICmp(I
.ICMP_EQ
, A
, ConstantInt::get(A
->getType(), Shift
));
1035 // Shifting const2 will never be equal to const1.
1036 // FIXME: This should always be handled by InstSimplify?
1037 auto *TorF
= ConstantInt::get(I
.getType(), I
.getPredicate() == I
.ICMP_NE
);
1038 return replaceInstUsesWith(I
, TorF
);
1041 /// Handle "(icmp eq/ne (shl AP2, A), AP1)" ->
1042 /// (icmp eq/ne A, TrailingZeros(AP1) - TrailingZeros(AP2)).
1043 Instruction
*InstCombinerImpl::foldICmpShlConstConst(ICmpInst
&I
, Value
*A
,
1046 assert(I
.isEquality() && "Cannot fold icmp gt/lt");
1048 auto getICmp
= [&I
](CmpInst::Predicate Pred
, Value
*LHS
, Value
*RHS
) {
1049 if (I
.getPredicate() == I
.ICMP_NE
)
1050 Pred
= CmpInst::getInversePredicate(Pred
);
1051 return new ICmpInst(Pred
, LHS
, RHS
);
1054 // Don't bother doing any work for cases which InstSimplify handles.
1058 unsigned AP2TrailingZeros
= AP2
.countr_zero();
1060 if (!AP1
&& AP2TrailingZeros
!= 0)
1063 ConstantInt::get(A
->getType(), AP2
.getBitWidth() - AP2TrailingZeros
));
1066 return getICmp(I
.ICMP_EQ
, A
, ConstantInt::getNullValue(A
->getType()));
1068 // Get the distance between the lowest bits that are set.
1069 int Shift
= AP1
.countr_zero() - AP2TrailingZeros
;
1071 if (Shift
> 0 && AP2
.shl(Shift
) == AP1
)
1072 return getICmp(I
.ICMP_EQ
, A
, ConstantInt::get(A
->getType(), Shift
));
1074 // Shifting const2 will never be equal to const1.
1075 // FIXME: This should always be handled by InstSimplify?
1076 auto *TorF
= ConstantInt::get(I
.getType(), I
.getPredicate() == I
.ICMP_NE
);
1077 return replaceInstUsesWith(I
, TorF
);
1080 /// The caller has matched a pattern of the form:
1081 /// I = icmp ugt (add (add A, B), CI2), CI1
1082 /// If this is of the form:
1084 /// if (sum+128 >u 255)
1085 /// Then replace it with llvm.sadd.with.overflow.i8.
1087 static Instruction
*processUGT_ADDCST_ADD(ICmpInst
&I
, Value
*A
, Value
*B
,
1088 ConstantInt
*CI2
, ConstantInt
*CI1
,
1089 InstCombinerImpl
&IC
) {
1090 // The transformation we're trying to do here is to transform this into an
1091 // llvm.sadd.with.overflow. To do this, we have to replace the original add
1092 // with a narrower add, and discard the add-with-constant that is part of the
1093 // range check (if we can't eliminate it, this isn't profitable).
1095 // In order to eliminate the add-with-constant, the compare can be its only
1097 Instruction
*AddWithCst
= cast
<Instruction
>(I
.getOperand(0));
1098 if (!AddWithCst
->hasOneUse())
1101 // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
1102 if (!CI2
->getValue().isPowerOf2())
1104 unsigned NewWidth
= CI2
->getValue().countr_zero();
1105 if (NewWidth
!= 7 && NewWidth
!= 15 && NewWidth
!= 31)
1108 // The width of the new add formed is 1 more than the bias.
1111 // Check to see that CI1 is an all-ones value with NewWidth bits.
1112 if (CI1
->getBitWidth() == NewWidth
||
1113 CI1
->getValue() != APInt::getLowBitsSet(CI1
->getBitWidth(), NewWidth
))
1116 // This is only really a signed overflow check if the inputs have been
1117 // sign-extended; check for that condition. For example, if CI2 is 2^31 and
1118 // the operands of the add are 64 bits wide, we need at least 33 sign bits.
1119 if (IC
.ComputeMaxSignificantBits(A
, 0, &I
) > NewWidth
||
1120 IC
.ComputeMaxSignificantBits(B
, 0, &I
) > NewWidth
)
1123 // In order to replace the original add with a narrower
1124 // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
1125 // and truncates that discard the high bits of the add. Verify that this is
1127 Instruction
*OrigAdd
= cast
<Instruction
>(AddWithCst
->getOperand(0));
1128 for (User
*U
: OrigAdd
->users()) {
1129 if (U
== AddWithCst
)
1132 // Only accept truncates for now. We would really like a nice recursive
1133 // predicate like SimplifyDemandedBits, but which goes downwards the use-def
1134 // chain to see which bits of a value are actually demanded. If the
1135 // original add had another add which was then immediately truncated, we
1136 // could still do the transformation.
1137 TruncInst
*TI
= dyn_cast
<TruncInst
>(U
);
1138 if (!TI
|| TI
->getType()->getPrimitiveSizeInBits() > NewWidth
)
1142 // If the pattern matches, truncate the inputs to the narrower type and
1143 // use the sadd_with_overflow intrinsic to efficiently compute both the
1144 // result and the overflow bit.
1145 Type
*NewType
= IntegerType::get(OrigAdd
->getContext(), NewWidth
);
1146 Function
*F
= Intrinsic::getOrInsertDeclaration(
1147 I
.getModule(), Intrinsic::sadd_with_overflow
, NewType
);
1149 InstCombiner::BuilderTy
&Builder
= IC
.Builder
;
1151 // Put the new code above the original add, in case there are any uses of the
1152 // add between the add and the compare.
1153 Builder
.SetInsertPoint(OrigAdd
);
1155 Value
*TruncA
= Builder
.CreateTrunc(A
, NewType
, A
->getName() + ".trunc");
1156 Value
*TruncB
= Builder
.CreateTrunc(B
, NewType
, B
->getName() + ".trunc");
1157 CallInst
*Call
= Builder
.CreateCall(F
, {TruncA
, TruncB
}, "sadd");
1158 Value
*Add
= Builder
.CreateExtractValue(Call
, 0, "sadd.result");
1159 Value
*ZExt
= Builder
.CreateZExt(Add
, OrigAdd
->getType());
1161 // The inner add was the result of the narrow add, zero extended to the
1162 // wider type. Replace it with the result computed by the intrinsic.
1163 IC
.replaceInstUsesWith(*OrigAdd
, ZExt
);
1164 IC
.eraseInstFromFunction(*OrigAdd
);
1166 // The original icmp gets replaced with the overflow value.
1167 return ExtractValueInst::Create(Call
, 1, "sadd.overflow");
1171 /// icmp eq/ne (urem/srem %x, %y), 0
1172 /// iff %y is a power-of-two, we can replace this with a bit test:
1173 /// icmp eq/ne (and %x, (add %y, -1)), 0
1174 Instruction
*InstCombinerImpl::foldIRemByPowerOfTwoToBitTest(ICmpInst
&I
) {
1175 // This fold is only valid for equality predicates.
1176 if (!I
.isEquality())
1179 Value
*X
, *Y
, *Zero
;
1180 if (!match(&I
, m_ICmp(Pred
, m_OneUse(m_IRem(m_Value(X
), m_Value(Y
))),
1181 m_CombineAnd(m_Zero(), m_Value(Zero
)))))
1183 if (!isKnownToBeAPowerOfTwo(Y
, /*OrZero*/ true, 0, &I
))
1185 // This may increase instruction count, we don't enforce that Y is a constant.
1186 Value
*Mask
= Builder
.CreateAdd(Y
, Constant::getAllOnesValue(Y
->getType()));
1187 Value
*Masked
= Builder
.CreateAnd(X
, Mask
);
1188 return ICmpInst::Create(Instruction::ICmp
, Pred
, Masked
, Zero
);
1191 /// Fold equality-comparison between zero and any (maybe truncated) right-shift
1192 /// by one-less-than-bitwidth into a sign test on the original value.
1193 Instruction
*InstCombinerImpl::foldSignBitTest(ICmpInst
&I
) {
1196 if (!I
.isEquality() || !match(&I
, m_ICmp(Pred
, m_Instruction(Val
), m_Zero())))
1203 if (match(Val
, m_TruncOrSelf(m_Shr(m_Value(X
), m_Constant(C
))))) {
1205 unsigned XBitWidth
= XTy
->getScalarSizeInBits();
1206 if (!match(C
, m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_EQ
,
1207 APInt(XBitWidth
, XBitWidth
- 1))))
1209 } else if (isa
<BinaryOperator
>(Val
) &&
1210 (X
= reassociateShiftAmtsOfTwoSameDirectionShifts(
1211 cast
<BinaryOperator
>(Val
), SQ
.getWithInstruction(Val
),
1212 /*AnalyzeForSignBitExtraction=*/true))) {
1217 return ICmpInst::Create(Instruction::ICmp
,
1218 Pred
== ICmpInst::ICMP_EQ
? ICmpInst::ICMP_SGE
1219 : ICmpInst::ICMP_SLT
,
1220 X
, ConstantInt::getNullValue(XTy
));
1223 // Handle icmp pred X, 0
1224 Instruction
*InstCombinerImpl::foldICmpWithZero(ICmpInst
&Cmp
) {
1225 CmpInst::Predicate Pred
= Cmp
.getPredicate();
1226 if (!match(Cmp
.getOperand(1), m_Zero()))
1229 // (icmp sgt smin(PosA, B) 0) -> (icmp sgt B 0)
1230 if (Pred
== ICmpInst::ICMP_SGT
) {
1232 if (match(Cmp
.getOperand(0), m_SMin(m_Value(A
), m_Value(B
)))) {
1233 if (isKnownPositive(A
, SQ
.getWithInstruction(&Cmp
)))
1234 return new ICmpInst(Pred
, B
, Cmp
.getOperand(1));
1235 if (isKnownPositive(B
, SQ
.getWithInstruction(&Cmp
)))
1236 return new ICmpInst(Pred
, A
, Cmp
.getOperand(1));
1240 if (Instruction
*New
= foldIRemByPowerOfTwoToBitTest(Cmp
))
1244 // icmp eq/ne (urem %x, %y), 0
1245 // Iff %x has 0 or 1 bits set, and %y has at least 2 bits set, omit 'urem':
1248 if (match(Cmp
.getOperand(0), m_URem(m_Value(X
), m_Value(Y
))) &&
1249 ICmpInst::isEquality(Pred
)) {
1250 KnownBits XKnown
= computeKnownBits(X
, 0, &Cmp
);
1251 KnownBits YKnown
= computeKnownBits(Y
, 0, &Cmp
);
1252 if (XKnown
.countMaxPopulation() == 1 && YKnown
.countMinPopulation() >= 2)
1253 return new ICmpInst(Pred
, X
, Cmp
.getOperand(1));
1256 // (icmp eq/ne (mul X Y)) -> (icmp eq/ne X/Y) if we know about whether X/Y are
1257 // odd/non-zero/there is no overflow.
1258 if (match(Cmp
.getOperand(0), m_Mul(m_Value(X
), m_Value(Y
))) &&
1259 ICmpInst::isEquality(Pred
)) {
1261 KnownBits XKnown
= computeKnownBits(X
, 0, &Cmp
);
1264 if (XKnown
.countMaxTrailingZeros() == 0)
1265 return new ICmpInst(Pred
, Y
, Cmp
.getOperand(1));
1267 KnownBits YKnown
= computeKnownBits(Y
, 0, &Cmp
);
1270 if (YKnown
.countMaxTrailingZeros() == 0)
1271 return new ICmpInst(Pred
, X
, Cmp
.getOperand(1));
1273 auto *BO0
= cast
<OverflowingBinaryOperator
>(Cmp
.getOperand(0));
1274 if (BO0
->hasNoUnsignedWrap() || BO0
->hasNoSignedWrap()) {
1275 const SimplifyQuery Q
= SQ
.getWithInstruction(&Cmp
);
1276 // `isKnownNonZero` does more analysis than just `!KnownBits.One.isZero()`
1277 // but to avoid unnecessary work, first just if this is an obvious case.
1279 // if X non-zero and NoOverflow(X * Y)
1281 if (!XKnown
.One
.isZero() || isKnownNonZero(X
, Q
))
1282 return new ICmpInst(Pred
, Y
, Cmp
.getOperand(1));
1284 // if Y non-zero and NoOverflow(X * Y)
1286 if (!YKnown
.One
.isZero() || isKnownNonZero(Y
, Q
))
1287 return new ICmpInst(Pred
, X
, Cmp
.getOperand(1));
1289 // Note, we are skipping cases:
1290 // if Y % 2 != 0 AND X % 2 != 0
1292 // if X non-zero and Y non-zero and NoOverflow(X * Y)
1294 // Those can be simplified later as we would have already replaced the (icmp
1295 // eq/ne (mul X, Y)) with (icmp eq/ne X/Y) and if X/Y is known non-zero that
1296 // will fold to a constant elsewhere.
1301 /// Fold icmp Pred X, C.
1302 /// TODO: This code structure does not make sense. The saturating add fold
1303 /// should be moved to some other helper and extended as noted below (it is also
1304 /// possible that code has been made unnecessary - do we canonicalize IR to
1305 /// overflow/saturating intrinsics or not?).
1306 Instruction
*InstCombinerImpl::foldICmpWithConstant(ICmpInst
&Cmp
) {
1307 // Match the following pattern, which is a common idiom when writing
1308 // overflow-safe integer arithmetic functions. The source performs an addition
1309 // in wider type and explicitly checks for overflow using comparisons against
1310 // INT_MIN and INT_MAX. Simplify by using the sadd_with_overflow intrinsic.
1312 // TODO: This could probably be generalized to handle other overflow-safe
1313 // operations if we worked out the formulas to compute the appropriate magic
1317 // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8
1318 CmpInst::Predicate Pred
= Cmp
.getPredicate();
1319 Value
*Op0
= Cmp
.getOperand(0), *Op1
= Cmp
.getOperand(1);
1321 ConstantInt
*CI
, *CI2
; // I = icmp ugt (add (add A, B), CI2), CI
1322 if (Pred
== ICmpInst::ICMP_UGT
&& match(Op1
, m_ConstantInt(CI
)) &&
1323 match(Op0
, m_Add(m_Add(m_Value(A
), m_Value(B
)), m_ConstantInt(CI2
))))
1324 if (Instruction
*Res
= processUGT_ADDCST_ADD(Cmp
, A
, B
, CI2
, CI
, *this))
1327 // icmp(phi(C1, C2, ...), C) -> phi(icmp(C1, C), icmp(C2, C), ...).
1328 Constant
*C
= dyn_cast
<Constant
>(Op1
);
1332 if (auto *Phi
= dyn_cast
<PHINode
>(Op0
))
1333 if (all_of(Phi
->operands(), [](Value
*V
) { return isa
<Constant
>(V
); })) {
1334 SmallVector
<Constant
*> Ops
;
1335 for (Value
*V
: Phi
->incoming_values()) {
1337 ConstantFoldCompareInstOperands(Pred
, cast
<Constant
>(V
), C
, DL
);
1342 Builder
.SetInsertPoint(Phi
);
1343 PHINode
*NewPhi
= Builder
.CreatePHI(Cmp
.getType(), Phi
->getNumOperands());
1344 for (auto [V
, Pred
] : zip(Ops
, Phi
->blocks()))
1345 NewPhi
->addIncoming(V
, Pred
);
1346 return replaceInstUsesWith(Cmp
, NewPhi
);
1349 if (Instruction
*R
= tryFoldInstWithCtpopWithNot(&Cmp
))
1355 /// Canonicalize icmp instructions based on dominating conditions.
1356 Instruction
*InstCombinerImpl::foldICmpWithDominatingICmp(ICmpInst
&Cmp
) {
1357 // We already checked simple implication in InstSimplify, only handle complex
1359 Value
*X
= Cmp
.getOperand(0), *Y
= Cmp
.getOperand(1);
1361 if (!match(Y
, m_APInt(C
)))
1364 CmpInst::Predicate Pred
= Cmp
.getPredicate();
1365 ConstantRange CR
= ConstantRange::makeExactICmpRegion(Pred
, *C
);
1367 auto handleDomCond
= [&](ICmpInst::Predicate DomPred
,
1368 const APInt
*DomC
) -> Instruction
* {
1369 // We have 2 compares of a variable with constants. Calculate the constant
1370 // ranges of those compares to see if we can transform the 2nd compare:
1372 // DomCond = icmp DomPred X, DomC
1373 // br DomCond, CmpBB, FalseBB
1375 // Cmp = icmp Pred X, C
1376 ConstantRange DominatingCR
=
1377 ConstantRange::makeExactICmpRegion(DomPred
, *DomC
);
1378 ConstantRange Intersection
= DominatingCR
.intersectWith(CR
);
1379 ConstantRange Difference
= DominatingCR
.difference(CR
);
1380 if (Intersection
.isEmptySet())
1381 return replaceInstUsesWith(Cmp
, Builder
.getFalse());
1382 if (Difference
.isEmptySet())
1383 return replaceInstUsesWith(Cmp
, Builder
.getTrue());
1385 // Canonicalizing a sign bit comparison that gets used in a branch,
1386 // pessimizes codegen by generating branch on zero instruction instead
1387 // of a test and branch. So we avoid canonicalizing in such situations
1388 // because test and branch instruction has better branch displacement
1389 // than compare and branch instruction.
1391 bool IsSignBit
= isSignBitCheck(Pred
, *C
, UnusedBit
);
1392 if (Cmp
.isEquality() || (IsSignBit
&& hasBranchUse(Cmp
)))
1395 // Avoid an infinite loop with min/max canonicalization.
1396 // TODO: This will be unnecessary if we canonicalize to min/max intrinsics.
1397 if (Cmp
.hasOneUse() &&
1398 match(Cmp
.user_back(), m_MaxOrMin(m_Value(), m_Value())))
1401 if (const APInt
*EqC
= Intersection
.getSingleElement())
1402 return new ICmpInst(ICmpInst::ICMP_EQ
, X
, Builder
.getInt(*EqC
));
1403 if (const APInt
*NeC
= Difference
.getSingleElement())
1404 return new ICmpInst(ICmpInst::ICMP_NE
, X
, Builder
.getInt(*NeC
));
1408 for (BranchInst
*BI
: DC
.conditionsFor(X
)) {
1409 CmpPredicate DomPred
;
1411 if (!match(BI
->getCondition(),
1412 m_ICmp(DomPred
, m_Specific(X
), m_APInt(DomC
))))
1415 BasicBlockEdge
Edge0(BI
->getParent(), BI
->getSuccessor(0));
1416 if (DT
.dominates(Edge0
, Cmp
.getParent())) {
1417 if (auto *V
= handleDomCond(DomPred
, DomC
))
1420 BasicBlockEdge
Edge1(BI
->getParent(), BI
->getSuccessor(1));
1421 if (DT
.dominates(Edge1
, Cmp
.getParent()))
1423 handleDomCond(CmpInst::getInversePredicate(DomPred
), DomC
))
1431 /// Fold icmp (trunc X), C.
1432 Instruction
*InstCombinerImpl::foldICmpTruncConstant(ICmpInst
&Cmp
,
1435 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
1436 Value
*X
= Trunc
->getOperand(0);
1437 Type
*SrcTy
= X
->getType();
1438 unsigned DstBits
= Trunc
->getType()->getScalarSizeInBits(),
1439 SrcBits
= SrcTy
->getScalarSizeInBits();
1441 // Match (icmp pred (trunc nuw/nsw X), C)
1442 // Which we can convert to (icmp pred X, (sext/zext C))
1443 if (shouldChangeType(Trunc
->getType(), SrcTy
)) {
1444 if (Trunc
->hasNoSignedWrap())
1445 return new ICmpInst(Pred
, X
, ConstantInt::get(SrcTy
, C
.sext(SrcBits
)));
1446 if (!Cmp
.isSigned() && Trunc
->hasNoUnsignedWrap())
1447 return new ICmpInst(Pred
, X
, ConstantInt::get(SrcTy
, C
.zext(SrcBits
)));
1450 if (C
.isOne() && C
.getBitWidth() > 1) {
1451 // icmp slt trunc(signum(V)) 1 --> icmp slt V, 1
1453 if (Pred
== ICmpInst::ICMP_SLT
&& match(X
, m_Signum(m_Value(V
))))
1454 return new ICmpInst(ICmpInst::ICMP_SLT
, V
,
1455 ConstantInt::get(V
->getType(), 1));
1458 // TODO: Handle any shifted constant by subtracting trailing zeros.
1459 // TODO: Handle non-equality predicates.
1461 if (Cmp
.isEquality() && match(X
, m_Shl(m_One(), m_Value(Y
)))) {
1462 // (trunc (1 << Y) to iN) == 0 --> Y u>= N
1463 // (trunc (1 << Y) to iN) != 0 --> Y u< N
1465 auto NewPred
= (Pred
== Cmp
.ICMP_EQ
) ? Cmp
.ICMP_UGE
: Cmp
.ICMP_ULT
;
1466 return new ICmpInst(NewPred
, Y
, ConstantInt::get(SrcTy
, DstBits
));
1468 // (trunc (1 << Y) to iN) == 2**C --> Y == C
1469 // (trunc (1 << Y) to iN) != 2**C --> Y != C
1471 return new ICmpInst(Pred
, Y
, ConstantInt::get(SrcTy
, C
.logBase2()));
1474 if (Cmp
.isEquality() && Trunc
->hasOneUse()) {
1475 // Canonicalize to a mask and wider compare if the wide type is suitable:
1476 // (trunc X to i8) == C --> (X & 0xff) == (zext C)
1477 if (!SrcTy
->isVectorTy() && shouldChangeType(DstBits
, SrcBits
)) {
1479 ConstantInt::get(SrcTy
, APInt::getLowBitsSet(SrcBits
, DstBits
));
1480 Value
*And
= Builder
.CreateAnd(X
, Mask
);
1481 Constant
*WideC
= ConstantInt::get(SrcTy
, C
.zext(SrcBits
));
1482 return new ICmpInst(Pred
, And
, WideC
);
1485 // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
1486 // of the high bits truncated out of x are known.
1487 KnownBits Known
= computeKnownBits(X
, 0, &Cmp
);
1489 // If all the high bits are known, we can do this xform.
1490 if ((Known
.Zero
| Known
.One
).countl_one() >= SrcBits
- DstBits
) {
1491 // Pull in the high bits from known-ones set.
1492 APInt NewRHS
= C
.zext(SrcBits
);
1493 NewRHS
|= Known
.One
& APInt::getHighBitsSet(SrcBits
, SrcBits
- DstBits
);
1494 return new ICmpInst(Pred
, X
, ConstantInt::get(SrcTy
, NewRHS
));
1498 // Look through truncated right-shift of the sign-bit for a sign-bit check:
1499 // trunc iN (ShOp >> ShAmtC) to i[N - ShAmtC] < 0 --> ShOp < 0
1500 // trunc iN (ShOp >> ShAmtC) to i[N - ShAmtC] > -1 --> ShOp > -1
1502 const APInt
*ShAmtC
;
1504 if (isSignBitCheck(Pred
, C
, TrueIfSigned
) &&
1505 match(X
, m_Shr(m_Value(ShOp
), m_APInt(ShAmtC
))) &&
1506 DstBits
== SrcBits
- ShAmtC
->getZExtValue()) {
1507 return TrueIfSigned
? new ICmpInst(ICmpInst::ICMP_SLT
, ShOp
,
1508 ConstantInt::getNullValue(SrcTy
))
1509 : new ICmpInst(ICmpInst::ICMP_SGT
, ShOp
,
1510 ConstantInt::getAllOnesValue(SrcTy
));
1516 /// Fold icmp (trunc nuw/nsw X), (trunc nuw/nsw Y).
1517 /// Fold icmp (trunc nuw/nsw X), (zext/sext Y).
1519 InstCombinerImpl::foldICmpTruncWithTruncOrExt(ICmpInst
&Cmp
,
1520 const SimplifyQuery
&Q
) {
1523 bool YIsSExt
= false;
1524 // Try to match icmp (trunc X), (trunc Y)
1525 if (match(&Cmp
, m_ICmp(Pred
, m_Trunc(m_Value(X
)), m_Trunc(m_Value(Y
))))) {
1526 unsigned NoWrapFlags
= cast
<TruncInst
>(Cmp
.getOperand(0))->getNoWrapKind() &
1527 cast
<TruncInst
>(Cmp
.getOperand(1))->getNoWrapKind();
1528 if (Cmp
.isSigned()) {
1529 // For signed comparisons, both truncs must be nsw.
1530 if (!(NoWrapFlags
& TruncInst::NoSignedWrap
))
1533 // For unsigned and equality comparisons, either both must be nuw or
1534 // both must be nsw, we don't care which.
1539 if (X
->getType() != Y
->getType() &&
1540 (!Cmp
.getOperand(0)->hasOneUse() || !Cmp
.getOperand(1)->hasOneUse()))
1542 if (!isDesirableIntType(X
->getType()->getScalarSizeInBits()) &&
1543 isDesirableIntType(Y
->getType()->getScalarSizeInBits())) {
1545 Pred
= Cmp
.getSwappedPredicate(Pred
);
1547 YIsSExt
= !(NoWrapFlags
& TruncInst::NoUnsignedWrap
);
1549 // Try to match icmp (trunc nuw X), (zext Y)
1550 else if (!Cmp
.isSigned() &&
1551 match(&Cmp
, m_c_ICmp(Pred
, m_NUWTrunc(m_Value(X
)),
1552 m_OneUse(m_ZExt(m_Value(Y
)))))) {
1553 // Can fold trunc nuw + zext for unsigned and equality predicates.
1555 // Try to match icmp (trunc nsw X), (sext Y)
1556 else if (match(&Cmp
, m_c_ICmp(Pred
, m_NSWTrunc(m_Value(X
)),
1557 m_OneUse(m_ZExtOrSExt(m_Value(Y
)))))) {
1558 // Can fold trunc nsw + zext/sext for all predicates.
1560 isa
<SExtInst
>(Cmp
.getOperand(0)) || isa
<SExtInst
>(Cmp
.getOperand(1));
1564 Type
*TruncTy
= Cmp
.getOperand(0)->getType();
1565 unsigned TruncBits
= TruncTy
->getScalarSizeInBits();
1567 // If this transform will end up changing from desirable types -> undesirable
1569 if (isDesirableIntType(TruncBits
) &&
1570 !isDesirableIntType(X
->getType()->getScalarSizeInBits()))
1573 Value
*NewY
= Builder
.CreateIntCast(Y
, X
->getType(), YIsSExt
);
1574 return new ICmpInst(Pred
, X
, NewY
);
1577 /// Fold icmp (xor X, Y), C.
1578 Instruction
*InstCombinerImpl::foldICmpXorConstant(ICmpInst
&Cmp
,
1579 BinaryOperator
*Xor
,
1581 if (Instruction
*I
= foldICmpXorShiftConst(Cmp
, Xor
, C
))
1584 Value
*X
= Xor
->getOperand(0);
1585 Value
*Y
= Xor
->getOperand(1);
1587 if (!match(Y
, m_APInt(XorC
)))
1590 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
1592 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
1593 bool TrueIfSigned
= false;
1594 if (isSignBitCheck(Cmp
.getPredicate(), C
, TrueIfSigned
)) {
1596 // If the sign bit of the XorCst is not set, there is no change to
1597 // the operation, just stop using the Xor.
1598 if (!XorC
->isNegative())
1599 return replaceOperand(Cmp
, 0, X
);
1601 // Emit the opposite comparison.
1603 return new ICmpInst(ICmpInst::ICMP_SGT
, X
,
1604 ConstantInt::getAllOnesValue(X
->getType()));
1606 return new ICmpInst(ICmpInst::ICMP_SLT
, X
,
1607 ConstantInt::getNullValue(X
->getType()));
1610 if (Xor
->hasOneUse()) {
1611 // (icmp u/s (xor X SignMask), C) -> (icmp s/u X, (xor C SignMask))
1612 if (!Cmp
.isEquality() && XorC
->isSignMask()) {
1613 Pred
= Cmp
.getFlippedSignednessPredicate();
1614 return new ICmpInst(Pred
, X
, ConstantInt::get(X
->getType(), C
^ *XorC
));
1617 // (icmp u/s (xor X ~SignMask), C) -> (icmp s/u X, (xor C ~SignMask))
1618 if (!Cmp
.isEquality() && XorC
->isMaxSignedValue()) {
1619 Pred
= Cmp
.getFlippedSignednessPredicate();
1620 Pred
= Cmp
.getSwappedPredicate(Pred
);
1621 return new ICmpInst(Pred
, X
, ConstantInt::get(X
->getType(), C
^ *XorC
));
1625 // Mask constant magic can eliminate an 'xor' with unsigned compares.
1626 if (Pred
== ICmpInst::ICMP_UGT
) {
1627 // (xor X, ~C) >u C --> X <u ~C (when C+1 is a power of 2)
1628 if (*XorC
== ~C
&& (C
+ 1).isPowerOf2())
1629 return new ICmpInst(ICmpInst::ICMP_ULT
, X
, Y
);
1630 // (xor X, C) >u C --> X >u C (when C+1 is a power of 2)
1631 if (*XorC
== C
&& (C
+ 1).isPowerOf2())
1632 return new ICmpInst(ICmpInst::ICMP_UGT
, X
, Y
);
1634 if (Pred
== ICmpInst::ICMP_ULT
) {
1635 // (xor X, -C) <u C --> X >u ~C (when C is a power of 2)
1636 if (*XorC
== -C
&& C
.isPowerOf2())
1637 return new ICmpInst(ICmpInst::ICMP_UGT
, X
,
1638 ConstantInt::get(X
->getType(), ~C
));
1639 // (xor X, C) <u C --> X >u ~C (when -C is a power of 2)
1640 if (*XorC
== C
&& (-C
).isPowerOf2())
1641 return new ICmpInst(ICmpInst::ICMP_UGT
, X
,
1642 ConstantInt::get(X
->getType(), ~C
));
1647 /// For power-of-2 C:
1648 /// ((X s>> ShiftC) ^ X) u< C --> (X + C) u< (C << 1)
1649 /// ((X s>> ShiftC) ^ X) u> (C - 1) --> (X + C) u> ((C << 1) - 1)
1650 Instruction
*InstCombinerImpl::foldICmpXorShiftConst(ICmpInst
&Cmp
,
1651 BinaryOperator
*Xor
,
1653 CmpInst::Predicate Pred
= Cmp
.getPredicate();
1655 if (Pred
== ICmpInst::ICMP_ULT
)
1657 else if (Pred
== ICmpInst::ICMP_UGT
&& !C
.isMaxValue())
1661 if (!PowerOf2
.isPowerOf2())
1664 const APInt
*ShiftC
;
1665 if (!match(Xor
, m_OneUse(m_c_Xor(m_Value(X
),
1666 m_AShr(m_Deferred(X
), m_APInt(ShiftC
))))))
1668 uint64_t Shift
= ShiftC
->getLimitedValue();
1669 Type
*XType
= X
->getType();
1670 if (Shift
== 0 || PowerOf2
.isMinSignedValue())
1672 Value
*Add
= Builder
.CreateAdd(X
, ConstantInt::get(XType
, PowerOf2
));
1674 Pred
== ICmpInst::ICMP_ULT
? PowerOf2
<< 1 : ((PowerOf2
<< 1) - 1);
1675 return new ICmpInst(Pred
, Add
, ConstantInt::get(XType
, Bound
));
1678 /// Fold icmp (and (sh X, Y), C2), C1.
1679 Instruction
*InstCombinerImpl::foldICmpAndShift(ICmpInst
&Cmp
,
1680 BinaryOperator
*And
,
1683 BinaryOperator
*Shift
= dyn_cast
<BinaryOperator
>(And
->getOperand(0));
1684 if (!Shift
|| !Shift
->isShift())
1687 // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could
1688 // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in
1689 // code produced by the clang front-end, for bitfield access.
1690 // This seemingly simple opportunity to fold away a shift turns out to be
1691 // rather complicated. See PR17827 for details.
1692 unsigned ShiftOpcode
= Shift
->getOpcode();
1693 bool IsShl
= ShiftOpcode
== Instruction::Shl
;
1695 if (match(Shift
->getOperand(1), m_APInt(C3
))) {
1696 APInt NewAndCst
, NewCmpCst
;
1697 bool AnyCmpCstBitsShiftedOut
;
1698 if (ShiftOpcode
== Instruction::Shl
) {
1699 // For a left shift, we can fold if the comparison is not signed. We can
1700 // also fold a signed comparison if the mask value and comparison value
1701 // are not negative. These constraints may not be obvious, but we can
1702 // prove that they are correct using an SMT solver.
1703 if (Cmp
.isSigned() && (C2
.isNegative() || C1
.isNegative()))
1706 NewCmpCst
= C1
.lshr(*C3
);
1707 NewAndCst
= C2
.lshr(*C3
);
1708 AnyCmpCstBitsShiftedOut
= NewCmpCst
.shl(*C3
) != C1
;
1709 } else if (ShiftOpcode
== Instruction::LShr
) {
1710 // For a logical right shift, we can fold if the comparison is not signed.
1711 // We can also fold a signed comparison if the shifted mask value and the
1712 // shifted comparison value are not negative. These constraints may not be
1713 // obvious, but we can prove that they are correct using an SMT solver.
1714 NewCmpCst
= C1
.shl(*C3
);
1715 NewAndCst
= C2
.shl(*C3
);
1716 AnyCmpCstBitsShiftedOut
= NewCmpCst
.lshr(*C3
) != C1
;
1717 if (Cmp
.isSigned() && (NewAndCst
.isNegative() || NewCmpCst
.isNegative()))
1720 // For an arithmetic shift, check that both constants don't use (in a
1721 // signed sense) the top bits being shifted out.
1722 assert(ShiftOpcode
== Instruction::AShr
&& "Unknown shift opcode");
1723 NewCmpCst
= C1
.shl(*C3
);
1724 NewAndCst
= C2
.shl(*C3
);
1725 AnyCmpCstBitsShiftedOut
= NewCmpCst
.ashr(*C3
) != C1
;
1726 if (NewAndCst
.ashr(*C3
) != C2
)
1730 if (AnyCmpCstBitsShiftedOut
) {
1731 // If we shifted bits out, the fold is not going to work out. As a
1732 // special case, check to see if this means that the result is always
1733 // true or false now.
1734 if (Cmp
.getPredicate() == ICmpInst::ICMP_EQ
)
1735 return replaceInstUsesWith(Cmp
, ConstantInt::getFalse(Cmp
.getType()));
1736 if (Cmp
.getPredicate() == ICmpInst::ICMP_NE
)
1737 return replaceInstUsesWith(Cmp
, ConstantInt::getTrue(Cmp
.getType()));
1739 Value
*NewAnd
= Builder
.CreateAnd(
1740 Shift
->getOperand(0), ConstantInt::get(And
->getType(), NewAndCst
));
1741 return new ICmpInst(Cmp
.getPredicate(),
1742 NewAnd
, ConstantInt::get(And
->getType(), NewCmpCst
));
1746 // Turn ((X >> Y) & C2) == 0 into (X & (C2 << Y)) == 0. The latter is
1747 // preferable because it allows the C2 << Y expression to be hoisted out of a
1748 // loop if Y is invariant and X is not.
1749 if (Shift
->hasOneUse() && C1
.isZero() && Cmp
.isEquality() &&
1750 !Shift
->isArithmeticShift() &&
1751 ((!IsShl
&& C2
.isOne()) || !isa
<Constant
>(Shift
->getOperand(0)))) {
1754 IsShl
? Builder
.CreateLShr(And
->getOperand(1), Shift
->getOperand(1))
1755 : Builder
.CreateShl(And
->getOperand(1), Shift
->getOperand(1));
1757 // Compute X & (C2 << Y).
1758 Value
*NewAnd
= Builder
.CreateAnd(Shift
->getOperand(0), NewShift
);
1759 return new ICmpInst(Cmp
.getPredicate(), NewAnd
, Cmp
.getOperand(1));
1765 /// Fold icmp (and X, C2), C1.
1766 Instruction
*InstCombinerImpl::foldICmpAndConstConst(ICmpInst
&Cmp
,
1767 BinaryOperator
*And
,
1769 bool isICMP_NE
= Cmp
.getPredicate() == ICmpInst::ICMP_NE
;
1771 // For vectors: icmp ne (and X, 1), 0 --> trunc X to N x i1
1772 // TODO: We canonicalize to the longer form for scalars because we have
1773 // better analysis/folds for icmp, and codegen may be better with icmp.
1774 if (isICMP_NE
&& Cmp
.getType()->isVectorTy() && C1
.isZero() &&
1775 match(And
->getOperand(1), m_One()))
1776 return new TruncInst(And
->getOperand(0), Cmp
.getType());
1780 if (!match(And
, m_And(m_Value(X
), m_APInt(C2
))))
1783 // (and X, highmask) s> [0, ~highmask] --> X s> ~highmask
1784 if (Cmp
.getPredicate() == ICmpInst::ICMP_SGT
&& C1
.ule(~*C2
) &&
1785 C2
->isNegatedPowerOf2())
1786 return new ICmpInst(ICmpInst::ICMP_SGT
, X
,
1787 ConstantInt::get(X
->getType(), ~*C2
));
1788 // (and X, highmask) s< [1, -highmask] --> X s< -highmask
1789 if (Cmp
.getPredicate() == ICmpInst::ICMP_SLT
&& !C1
.isSignMask() &&
1790 (C1
- 1).ule(~*C2
) && C2
->isNegatedPowerOf2() && !C2
->isSignMask())
1791 return new ICmpInst(ICmpInst::ICMP_SLT
, X
,
1792 ConstantInt::get(X
->getType(), -*C2
));
1794 // Don't perform the following transforms if the AND has multiple uses
1795 if (!And
->hasOneUse())
1798 if (Cmp
.isEquality() && C1
.isZero()) {
1799 // Restrict this fold to single-use 'and' (PR10267).
1800 // Replace (and X, (1 << size(X)-1) != 0) with X s< 0
1801 if (C2
->isSignMask()) {
1802 Constant
*Zero
= Constant::getNullValue(X
->getType());
1803 auto NewPred
= isICMP_NE
? ICmpInst::ICMP_SLT
: ICmpInst::ICMP_SGE
;
1804 return new ICmpInst(NewPred
, X
, Zero
);
1808 KnownBits Know
= computeKnownBits(And
->getOperand(0), 0, And
);
1809 // Set high zeros of C2 to allow matching negated power-of-2.
1810 NewC2
= *C2
| APInt::getHighBitsSet(C2
->getBitWidth(),
1811 Know
.countMinLeadingZeros());
1813 // Restrict this fold only for single-use 'and' (PR10267).
1814 // ((%x & C) == 0) --> %x u< (-C) iff (-C) is power of two.
1815 if (NewC2
.isNegatedPowerOf2()) {
1816 Constant
*NegBOC
= ConstantInt::get(And
->getType(), -NewC2
);
1817 auto NewPred
= isICMP_NE
? ICmpInst::ICMP_UGE
: ICmpInst::ICMP_ULT
;
1818 return new ICmpInst(NewPred
, X
, NegBOC
);
1822 // If the LHS is an 'and' of a truncate and we can widen the and/compare to
1823 // the input width without changing the value produced, eliminate the cast:
1825 // icmp (and (trunc W), C2), C1 -> icmp (and W, C2'), C1'
1827 // We can do this transformation if the constants do not have their sign bits
1828 // set or if it is an equality comparison. Extending a relational comparison
1829 // when we're checking the sign bit would not work.
1831 if (match(And
->getOperand(0), m_OneUse(m_Trunc(m_Value(W
)))) &&
1832 (Cmp
.isEquality() || (!C1
.isNegative() && !C2
->isNegative()))) {
1833 // TODO: Is this a good transform for vectors? Wider types may reduce
1834 // throughput. Should this transform be limited (even for scalars) by using
1835 // shouldChangeType()?
1836 if (!Cmp
.getType()->isVectorTy()) {
1837 Type
*WideType
= W
->getType();
1838 unsigned WideScalarBits
= WideType
->getScalarSizeInBits();
1839 Constant
*ZextC1
= ConstantInt::get(WideType
, C1
.zext(WideScalarBits
));
1840 Constant
*ZextC2
= ConstantInt::get(WideType
, C2
->zext(WideScalarBits
));
1841 Value
*NewAnd
= Builder
.CreateAnd(W
, ZextC2
, And
->getName());
1842 return new ICmpInst(Cmp
.getPredicate(), NewAnd
, ZextC1
);
1846 if (Instruction
*I
= foldICmpAndShift(Cmp
, And
, C1
, *C2
))
1849 // (icmp pred (and (or (lshr A, B), A), 1), 0) -->
1850 // (icmp pred (and A, (or (shl 1, B), 1), 0))
1852 // iff pred isn't signed
1853 if (!Cmp
.isSigned() && C1
.isZero() && And
->getOperand(0)->hasOneUse() &&
1854 match(And
->getOperand(1), m_One())) {
1855 Constant
*One
= cast
<Constant
>(And
->getOperand(1));
1856 Value
*Or
= And
->getOperand(0);
1857 Value
*A
, *B
, *LShr
;
1858 if (match(Or
, m_Or(m_Value(LShr
), m_Value(A
))) &&
1859 match(LShr
, m_LShr(m_Specific(A
), m_Value(B
)))) {
1860 unsigned UsesRemoved
= 0;
1861 if (And
->hasOneUse())
1863 if (Or
->hasOneUse())
1865 if (LShr
->hasOneUse())
1868 // Compute A & ((1 << B) | 1)
1869 unsigned RequireUsesRemoved
= match(B
, m_ImmConstant()) ? 1 : 3;
1870 if (UsesRemoved
>= RequireUsesRemoved
) {
1872 Builder
.CreateOr(Builder
.CreateShl(One
, B
, LShr
->getName(),
1874 One
, Or
->getName());
1875 Value
*NewAnd
= Builder
.CreateAnd(A
, NewOr
, And
->getName());
1876 return new ICmpInst(Cmp
.getPredicate(), NewAnd
, Cmp
.getOperand(1));
1881 // (icmp eq (and (bitcast X to int), ExponentMask), ExponentMask) -->
1882 // llvm.is.fpclass(X, fcInf|fcNan)
1883 // (icmp ne (and (bitcast X to int), ExponentMask), ExponentMask) -->
1884 // llvm.is.fpclass(X, ~(fcInf|fcNan))
1886 if (!Cmp
.getParent()->getParent()->hasFnAttribute(
1887 Attribute::NoImplicitFloat
) &&
1889 match(X
, m_OneUse(m_ElementWiseBitCast(m_Value(V
))))) {
1890 Type
*FPType
= V
->getType()->getScalarType();
1891 if (FPType
->isIEEELikeFPTy() && C1
== *C2
) {
1892 APInt ExponentMask
=
1893 APFloat::getInf(FPType
->getFltSemantics()).bitcastToAPInt();
1894 if (C1
== ExponentMask
) {
1895 unsigned Mask
= FPClassTest::fcNan
| FPClassTest::fcInf
;
1897 Mask
= ~Mask
& fcAllFlags
;
1898 return replaceInstUsesWith(Cmp
, Builder
.createIsFPClass(V
, Mask
));
1906 /// Fold icmp (and X, Y), C.
1907 Instruction
*InstCombinerImpl::foldICmpAndConstant(ICmpInst
&Cmp
,
1908 BinaryOperator
*And
,
1910 if (Instruction
*I
= foldICmpAndConstConst(Cmp
, And
, C
))
1913 const ICmpInst::Predicate Pred
= Cmp
.getPredicate();
1915 if (isSignBitCheck(Pred
, C
, TrueIfNeg
)) {
1916 // ((X - 1) & ~X) < 0 --> X == 0
1917 // ((X - 1) & ~X) >= 0 --> X != 0
1919 if (match(And
->getOperand(0), m_Add(m_Value(X
), m_AllOnes())) &&
1920 match(And
->getOperand(1), m_Not(m_Specific(X
)))) {
1921 auto NewPred
= TrueIfNeg
? CmpInst::ICMP_EQ
: CmpInst::ICMP_NE
;
1922 return new ICmpInst(NewPred
, X
, ConstantInt::getNullValue(X
->getType()));
1924 // (X & -X) < 0 --> X == MinSignedC
1925 // (X & -X) > -1 --> X != MinSignedC
1926 if (match(And
, m_c_And(m_Neg(m_Value(X
)), m_Deferred(X
)))) {
1927 Constant
*MinSignedC
= ConstantInt::get(
1929 APInt::getSignedMinValue(X
->getType()->getScalarSizeInBits()));
1930 auto NewPred
= TrueIfNeg
? CmpInst::ICMP_EQ
: CmpInst::ICMP_NE
;
1931 return new ICmpInst(NewPred
, X
, MinSignedC
);
1935 // TODO: These all require that Y is constant too, so refactor with the above.
1937 // Try to optimize things like "A[i] & 42 == 0" to index computations.
1938 Value
*X
= And
->getOperand(0);
1939 Value
*Y
= And
->getOperand(1);
1940 if (auto *C2
= dyn_cast
<ConstantInt
>(Y
))
1941 if (auto *LI
= dyn_cast
<LoadInst
>(X
))
1942 if (auto *GEP
= dyn_cast
<GetElementPtrInst
>(LI
->getOperand(0)))
1943 if (auto *GV
= dyn_cast
<GlobalVariable
>(GEP
->getOperand(0)))
1944 if (Instruction
*Res
=
1945 foldCmpLoadFromIndexedGlobal(LI
, GEP
, GV
, Cmp
, C2
))
1948 if (!Cmp
.isEquality())
1951 // X & -C == -C -> X > u ~C
1952 // X & -C != -C -> X <= u ~C
1953 // iff C is a power of 2
1954 if (Cmp
.getOperand(1) == Y
&& C
.isNegatedPowerOf2()) {
1956 Pred
== CmpInst::ICMP_EQ
? CmpInst::ICMP_UGT
: CmpInst::ICMP_ULE
;
1957 return new ICmpInst(NewPred
, X
, SubOne(cast
<Constant
>(Cmp
.getOperand(1))));
1960 // If we are testing the intersection of 2 select-of-nonzero-constants with no
1961 // common bits set, it's the same as checking if exactly one select condition
1963 // ((A ? TC : FC) & (B ? TC : FC)) == 0 --> xor A, B
1964 // ((A ? TC : FC) & (B ? TC : FC)) != 0 --> not(xor A, B)
1965 // TODO: Generalize for non-constant values.
1966 // TODO: Handle signed/unsigned predicates.
1967 // TODO: Handle other bitwise logic connectors.
1968 // TODO: Extend to handle a non-zero compare constant.
1969 if (C
.isZero() && (Pred
== CmpInst::ICMP_EQ
|| And
->hasOneUse())) {
1970 assert(Cmp
.isEquality() && "Not expecting non-equality predicates");
1972 const APInt
*TC
, *FC
;
1973 if (match(X
, m_Select(m_Value(A
), m_APInt(TC
), m_APInt(FC
))) &&
1975 m_Select(m_Value(B
), m_SpecificInt(*TC
), m_SpecificInt(*FC
))) &&
1976 !TC
->isZero() && !FC
->isZero() && !TC
->intersects(*FC
)) {
1977 Value
*R
= Builder
.CreateXor(A
, B
);
1978 if (Pred
== CmpInst::ICMP_NE
)
1979 R
= Builder
.CreateNot(R
);
1980 return replaceInstUsesWith(Cmp
, R
);
1984 // ((zext i1 X) & Y) == 0 --> !((trunc Y) & X)
1985 // ((zext i1 X) & Y) != 0 --> ((trunc Y) & X)
1986 // ((zext i1 X) & Y) == 1 --> ((trunc Y) & X)
1987 // ((zext i1 X) & Y) != 1 --> !((trunc Y) & X)
1988 if (match(And
, m_OneUse(m_c_And(m_OneUse(m_ZExt(m_Value(X
))), m_Value(Y
)))) &&
1989 X
->getType()->isIntOrIntVectorTy(1) && (C
.isZero() || C
.isOne())) {
1990 Value
*TruncY
= Builder
.CreateTrunc(Y
, X
->getType());
1991 if (C
.isZero() ^ (Pred
== CmpInst::ICMP_NE
)) {
1992 Value
*And
= Builder
.CreateAnd(TruncY
, X
);
1993 return BinaryOperator::CreateNot(And
);
1995 return BinaryOperator::CreateAnd(TruncY
, X
);
1998 // (icmp eq/ne (and (shl -1, X), Y), 0)
1999 // -> (icmp eq/ne (lshr Y, X), 0)
2000 // We could technically handle any C == 0 or (C < 0 && isOdd(C)) but it seems
2001 // highly unlikely the non-zero case will ever show up in code.
2003 match(And
, m_OneUse(m_c_And(m_OneUse(m_Shl(m_AllOnes(), m_Value(X
))),
2005 Value
*LShr
= Builder
.CreateLShr(Y
, X
);
2006 return new ICmpInst(Pred
, LShr
, Constant::getNullValue(LShr
->getType()));
2009 // (icmp eq/ne (and (add A, Addend), Msk), C)
2010 // -> (icmp eq/ne (and A, Msk), (and (sub C, Addend), Msk))
2013 const APInt
*Addend
, *Msk
;
2014 if (match(And
, m_And(m_OneUse(m_Add(m_Value(A
), m_APInt(Addend
))),
2016 Msk
->isMask() && C
.ule(*Msk
)) {
2017 APInt NewComperand
= (C
- *Addend
) & *Msk
;
2018 Value
* MaskA
= Builder
.CreateAnd(A
, ConstantInt::get(A
->getType(), *Msk
));
2019 return new ICmpInst(
2021 Constant::getIntegerValue(MaskA
->getType(), NewComperand
));
2028 /// Fold icmp eq/ne (or (xor/sub (X1, X2), xor/sub (X3, X4))), 0.
2029 static Value
*foldICmpOrXorSubChain(ICmpInst
&Cmp
, BinaryOperator
*Or
,
2030 InstCombiner::BuilderTy
&Builder
) {
2031 // Are we using xors or subs to bitwise check for a pair or pairs of
2032 // (in)equalities? Convert to a shorter form that has more potential to be
2033 // folded even further.
2034 // ((X1 ^/- X2) || (X3 ^/- X4)) == 0 --> (X1 == X2) && (X3 == X4)
2035 // ((X1 ^/- X2) || (X3 ^/- X4)) != 0 --> (X1 != X2) || (X3 != X4)
2036 // ((X1 ^/- X2) || (X3 ^/- X4) || (X5 ^/- X6)) == 0 -->
2037 // (X1 == X2) && (X3 == X4) && (X5 == X6)
2038 // ((X1 ^/- X2) || (X3 ^/- X4) || (X5 ^/- X6)) != 0 -->
2039 // (X1 != X2) || (X3 != X4) || (X5 != X6)
2040 SmallVector
<std::pair
<Value
*, Value
*>, 2> CmpValues
;
2041 SmallVector
<Value
*, 16> WorkList(1, Or
);
2043 while (!WorkList
.empty()) {
2044 auto MatchOrOperatorArgument
= [&](Value
*OrOperatorArgument
) {
2047 if (match(OrOperatorArgument
,
2048 m_OneUse(m_Xor(m_Value(Lhs
), m_Value(Rhs
))))) {
2049 CmpValues
.emplace_back(Lhs
, Rhs
);
2053 if (match(OrOperatorArgument
,
2054 m_OneUse(m_Sub(m_Value(Lhs
), m_Value(Rhs
))))) {
2055 CmpValues
.emplace_back(Lhs
, Rhs
);
2059 WorkList
.push_back(OrOperatorArgument
);
2062 Value
*CurrentValue
= WorkList
.pop_back_val();
2063 Value
*OrOperatorLhs
, *OrOperatorRhs
;
2065 if (!match(CurrentValue
,
2066 m_Or(m_Value(OrOperatorLhs
), m_Value(OrOperatorRhs
)))) {
2070 MatchOrOperatorArgument(OrOperatorRhs
);
2071 MatchOrOperatorArgument(OrOperatorLhs
);
2074 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2075 auto BOpc
= Pred
== CmpInst::ICMP_EQ
? Instruction::And
: Instruction::Or
;
2076 Value
*LhsCmp
= Builder
.CreateICmp(Pred
, CmpValues
.rbegin()->first
,
2077 CmpValues
.rbegin()->second
);
2079 for (auto It
= CmpValues
.rbegin() + 1; It
!= CmpValues
.rend(); ++It
) {
2080 Value
*RhsCmp
= Builder
.CreateICmp(Pred
, It
->first
, It
->second
);
2081 LhsCmp
= Builder
.CreateBinOp(BOpc
, LhsCmp
, RhsCmp
);
2087 /// Fold icmp (or X, Y), C.
2088 Instruction
*InstCombinerImpl::foldICmpOrConstant(ICmpInst
&Cmp
,
2091 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2093 // icmp slt signum(V) 1 --> icmp slt V, 1
2095 if (Pred
== ICmpInst::ICMP_SLT
&& match(Or
, m_Signum(m_Value(V
))))
2096 return new ICmpInst(ICmpInst::ICMP_SLT
, V
,
2097 ConstantInt::get(V
->getType(), 1));
2100 Value
*OrOp0
= Or
->getOperand(0), *OrOp1
= Or
->getOperand(1);
2102 // (icmp eq/ne (or disjoint x, C0), C1)
2103 // -> (icmp eq/ne x, C0^C1)
2104 if (Cmp
.isEquality() && match(OrOp1
, m_ImmConstant()) &&
2105 cast
<PossiblyDisjointInst
>(Or
)->isDisjoint()) {
2107 Builder
.CreateXor(OrOp1
, ConstantInt::get(OrOp1
->getType(), C
));
2108 return new ICmpInst(Pred
, OrOp0
, NewC
);
2112 if (match(OrOp1
, m_APInt(MaskC
)) && Cmp
.isEquality()) {
2113 if (*MaskC
== C
&& (C
+ 1).isPowerOf2()) {
2114 // X | C == C --> X <=u C
2115 // X | C != C --> X >u C
2116 // iff C+1 is a power of 2 (C is a bitmask of the low bits)
2117 Pred
= (Pred
== CmpInst::ICMP_EQ
) ? CmpInst::ICMP_ULE
: CmpInst::ICMP_UGT
;
2118 return new ICmpInst(Pred
, OrOp0
, OrOp1
);
2121 // More general: canonicalize 'equality with set bits mask' to
2122 // 'equality with clear bits mask'.
2123 // (X | MaskC) == C --> (X & ~MaskC) == C ^ MaskC
2124 // (X | MaskC) != C --> (X & ~MaskC) != C ^ MaskC
2125 if (Or
->hasOneUse()) {
2126 Value
*And
= Builder
.CreateAnd(OrOp0
, ~(*MaskC
));
2127 Constant
*NewC
= ConstantInt::get(Or
->getType(), C
^ (*MaskC
));
2128 return new ICmpInst(Pred
, And
, NewC
);
2132 // (X | (X-1)) s< 0 --> X s< 1
2133 // (X | (X-1)) s> -1 --> X s> 0
2136 if (isSignBitCheck(Pred
, C
, TrueIfSigned
) &&
2137 match(Or
, m_c_Or(m_Add(m_Value(X
), m_AllOnes()), m_Deferred(X
)))) {
2138 auto NewPred
= TrueIfSigned
? ICmpInst::ICMP_SLT
: ICmpInst::ICMP_SGT
;
2139 Constant
*NewC
= ConstantInt::get(X
->getType(), TrueIfSigned
? 1 : 0);
2140 return new ICmpInst(NewPred
, X
, NewC
);
2144 // icmp(X | OrC, C) --> icmp(X, 0)
2145 if (C
.isNonNegative() && match(Or
, m_Or(m_Value(X
), m_APInt(OrC
)))) {
2147 // X | OrC s< C --> X s< 0 iff OrC s>= C s>= 0
2148 case ICmpInst::ICMP_SLT
:
2149 // X | OrC s>= C --> X s>= 0 iff OrC s>= C s>= 0
2150 case ICmpInst::ICMP_SGE
:
2152 return new ICmpInst(Pred
, X
, ConstantInt::getNullValue(X
->getType()));
2154 // X | OrC s<= C --> X s< 0 iff OrC s> C s>= 0
2155 case ICmpInst::ICMP_SLE
:
2156 // X | OrC s> C --> X s>= 0 iff OrC s> C s>= 0
2157 case ICmpInst::ICMP_SGT
:
2159 return new ICmpInst(ICmpInst::getFlippedStrictnessPredicate(Pred
), X
,
2160 ConstantInt::getNullValue(X
->getType()));
2167 if (!Cmp
.isEquality() || !C
.isZero() || !Or
->hasOneUse())
2171 if (match(Or
, m_Or(m_PtrToInt(m_Value(P
)), m_PtrToInt(m_Value(Q
))))) {
2172 // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
2173 // -> and (icmp eq P, null), (icmp eq Q, null).
2175 Builder
.CreateICmp(Pred
, P
, ConstantInt::getNullValue(P
->getType()));
2177 Builder
.CreateICmp(Pred
, Q
, ConstantInt::getNullValue(Q
->getType()));
2178 auto BOpc
= Pred
== CmpInst::ICMP_EQ
? Instruction::And
: Instruction::Or
;
2179 return BinaryOperator::Create(BOpc
, CmpP
, CmpQ
);
2182 if (Value
*V
= foldICmpOrXorSubChain(Cmp
, Or
, Builder
))
2183 return replaceInstUsesWith(Cmp
, V
);
2188 /// Fold icmp (mul X, Y), C.
2189 Instruction
*InstCombinerImpl::foldICmpMulConstant(ICmpInst
&Cmp
,
2190 BinaryOperator
*Mul
,
2192 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2193 Type
*MulTy
= Mul
->getType();
2194 Value
*X
= Mul
->getOperand(0);
2196 // If there's no overflow:
2197 // X * X == 0 --> X == 0
2198 // X * X != 0 --> X != 0
2199 if (Cmp
.isEquality() && C
.isZero() && X
== Mul
->getOperand(1) &&
2200 (Mul
->hasNoUnsignedWrap() || Mul
->hasNoSignedWrap()))
2201 return new ICmpInst(Pred
, X
, ConstantInt::getNullValue(MulTy
));
2204 if (!match(Mul
->getOperand(1), m_APInt(MulC
)))
2207 // If this is a test of the sign bit and the multiply is sign-preserving with
2208 // a constant operand, use the multiply LHS operand instead:
2209 // (X * +MulC) < 0 --> X < 0
2210 // (X * -MulC) < 0 --> X > 0
2211 if (isSignTest(Pred
, C
) && Mul
->hasNoSignedWrap()) {
2212 if (MulC
->isNegative())
2213 Pred
= ICmpInst::getSwappedPredicate(Pred
);
2214 return new ICmpInst(Pred
, X
, ConstantInt::getNullValue(MulTy
));
2220 // If the multiply does not wrap or the constant is odd, try to divide the
2221 // compare constant by the multiplication factor.
2222 if (Cmp
.isEquality()) {
2223 // (mul nsw X, MulC) eq/ne C --> X eq/ne C /s MulC
2224 if (Mul
->hasNoSignedWrap() && C
.srem(*MulC
).isZero()) {
2225 Constant
*NewC
= ConstantInt::get(MulTy
, C
.sdiv(*MulC
));
2226 return new ICmpInst(Pred
, X
, NewC
);
2229 // C % MulC == 0 is weaker than we could use if MulC is odd because it
2230 // correct to transform if MulC * N == C including overflow. I.e with i8
2231 // (icmp eq (mul X, 5), 101) -> (icmp eq X, 225) but since 101 % 5 != 0, we
2233 if (C
.urem(*MulC
).isZero()) {
2234 // (mul nuw X, MulC) eq/ne C --> X eq/ne C /u MulC
2235 // (mul X, OddC) eq/ne N * C --> X eq/ne N
2236 if ((*MulC
& 1).isOne() || Mul
->hasNoUnsignedWrap()) {
2237 Constant
*NewC
= ConstantInt::get(MulTy
, C
.udiv(*MulC
));
2238 return new ICmpInst(Pred
, X
, NewC
);
2243 // With a matching no-overflow guarantee, fold the constants:
2244 // (X * MulC) < C --> X < (C / MulC)
2245 // (X * MulC) > C --> X > (C / MulC)
2246 // TODO: Assert that Pred is not equal to SGE, SLE, UGE, ULE?
2247 Constant
*NewC
= nullptr;
2248 if (Mul
->hasNoSignedWrap() && ICmpInst::isSigned(Pred
)) {
2249 // MININT / -1 --> overflow.
2250 if (C
.isMinSignedValue() && MulC
->isAllOnes())
2252 if (MulC
->isNegative())
2253 Pred
= ICmpInst::getSwappedPredicate(Pred
);
2255 if (Pred
== ICmpInst::ICMP_SLT
|| Pred
== ICmpInst::ICMP_SGE
) {
2256 NewC
= ConstantInt::get(
2257 MulTy
, APIntOps::RoundingSDiv(C
, *MulC
, APInt::Rounding::UP
));
2259 assert((Pred
== ICmpInst::ICMP_SLE
|| Pred
== ICmpInst::ICMP_SGT
) &&
2260 "Unexpected predicate");
2261 NewC
= ConstantInt::get(
2262 MulTy
, APIntOps::RoundingSDiv(C
, *MulC
, APInt::Rounding::DOWN
));
2264 } else if (Mul
->hasNoUnsignedWrap() && ICmpInst::isUnsigned(Pred
)) {
2265 if (Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_UGE
) {
2266 NewC
= ConstantInt::get(
2267 MulTy
, APIntOps::RoundingUDiv(C
, *MulC
, APInt::Rounding::UP
));
2269 assert((Pred
== ICmpInst::ICMP_ULE
|| Pred
== ICmpInst::ICMP_UGT
) &&
2270 "Unexpected predicate");
2271 NewC
= ConstantInt::get(
2272 MulTy
, APIntOps::RoundingUDiv(C
, *MulC
, APInt::Rounding::DOWN
));
2276 return NewC
? new ICmpInst(Pred
, X
, NewC
) : nullptr;
2279 /// Fold icmp (shl nuw C2, Y), C.
2280 static Instruction
*foldICmpShlLHSC(ICmpInst
&Cmp
, Instruction
*Shl
,
2284 if (!match(Shl
, m_NUWShl(m_APInt(C2
), m_Value(Y
))))
2287 Type
*ShiftType
= Shl
->getType();
2288 unsigned TypeBits
= C
.getBitWidth();
2289 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2290 if (Cmp
.isUnsigned()) {
2291 if (C2
->isZero() || C2
->ugt(C
))
2294 APInt::udivrem(C
, *C2
, Div
, Rem
);
2295 bool CIsPowerOf2
= Rem
.isZero() && Div
.isPowerOf2();
2297 // (1 << Y) pred C -> Y pred Log2(C)
2299 // (1 << Y) < 30 -> Y <= 4
2300 // (1 << Y) <= 30 -> Y <= 4
2301 // (1 << Y) >= 30 -> Y > 4
2302 // (1 << Y) > 30 -> Y > 4
2303 if (Pred
== ICmpInst::ICMP_ULT
)
2304 Pred
= ICmpInst::ICMP_ULE
;
2305 else if (Pred
== ICmpInst::ICMP_UGE
)
2306 Pred
= ICmpInst::ICMP_UGT
;
2309 unsigned CLog2
= Div
.logBase2();
2310 return new ICmpInst(Pred
, Y
, ConstantInt::get(ShiftType
, CLog2
));
2311 } else if (Cmp
.isSigned() && C2
->isOne()) {
2312 Constant
*BitWidthMinusOne
= ConstantInt::get(ShiftType
, TypeBits
- 1);
2313 // (1 << Y) > 0 -> Y != 31
2314 // (1 << Y) > C -> Y != 31 if C is negative.
2315 if (Pred
== ICmpInst::ICMP_SGT
&& C
.sle(0))
2316 return new ICmpInst(ICmpInst::ICMP_NE
, Y
, BitWidthMinusOne
);
2318 // (1 << Y) < 0 -> Y == 31
2319 // (1 << Y) < 1 -> Y == 31
2320 // (1 << Y) < C -> Y == 31 if C is negative and not signed min.
2321 // Exclude signed min by subtracting 1 and lower the upper bound to 0.
2322 if (Pred
== ICmpInst::ICMP_SLT
&& (C
-1).sle(0))
2323 return new ICmpInst(ICmpInst::ICMP_EQ
, Y
, BitWidthMinusOne
);
2329 /// Fold icmp (shl X, Y), C.
2330 Instruction
*InstCombinerImpl::foldICmpShlConstant(ICmpInst
&Cmp
,
2331 BinaryOperator
*Shl
,
2333 const APInt
*ShiftVal
;
2334 if (Cmp
.isEquality() && match(Shl
->getOperand(0), m_APInt(ShiftVal
)))
2335 return foldICmpShlConstConst(Cmp
, Shl
->getOperand(1), C
, *ShiftVal
);
2337 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2338 // (icmp pred (shl nuw&nsw X, Y), Csle0)
2339 // -> (icmp pred X, Csle0)
2341 // The idea is the nuw/nsw essentially freeze the sign bit for the shift op
2342 // so X's must be what is used.
2343 if (C
.sle(0) && Shl
->hasNoUnsignedWrap() && Shl
->hasNoSignedWrap())
2344 return new ICmpInst(Pred
, Shl
->getOperand(0), Cmp
.getOperand(1));
2346 // (icmp eq/ne (shl nuw|nsw X, Y), 0)
2347 // -> (icmp eq/ne X, 0)
2348 if (ICmpInst::isEquality(Pred
) && C
.isZero() &&
2349 (Shl
->hasNoUnsignedWrap() || Shl
->hasNoSignedWrap()))
2350 return new ICmpInst(Pred
, Shl
->getOperand(0), Cmp
.getOperand(1));
2352 // (icmp slt (shl nsw X, Y), 0/1)
2353 // -> (icmp slt X, 0/1)
2354 // (icmp sgt (shl nsw X, Y), 0/-1)
2355 // -> (icmp sgt X, 0/-1)
2357 // NB: sge/sle with a constant will canonicalize to sgt/slt.
2358 if (Shl
->hasNoSignedWrap() &&
2359 (Pred
== ICmpInst::ICMP_SGT
|| Pred
== ICmpInst::ICMP_SLT
))
2360 if (C
.isZero() || (Pred
== ICmpInst::ICMP_SGT
? C
.isAllOnes() : C
.isOne()))
2361 return new ICmpInst(Pred
, Shl
->getOperand(0), Cmp
.getOperand(1));
2363 const APInt
*ShiftAmt
;
2364 if (!match(Shl
->getOperand(1), m_APInt(ShiftAmt
)))
2365 return foldICmpShlLHSC(Cmp
, Shl
, C
);
2367 // Check that the shift amount is in range. If not, don't perform undefined
2368 // shifts. When the shift is visited, it will be simplified.
2369 unsigned TypeBits
= C
.getBitWidth();
2370 if (ShiftAmt
->uge(TypeBits
))
2373 Value
*X
= Shl
->getOperand(0);
2374 Type
*ShType
= Shl
->getType();
2376 // NSW guarantees that we are only shifting out sign bits from the high bits,
2377 // so we can ASHR the compare constant without needing a mask and eliminate
2379 if (Shl
->hasNoSignedWrap()) {
2380 if (Pred
== ICmpInst::ICMP_SGT
) {
2381 // icmp Pred (shl nsw X, ShiftAmt), C --> icmp Pred X, (C >>s ShiftAmt)
2382 APInt ShiftedC
= C
.ashr(*ShiftAmt
);
2383 return new ICmpInst(Pred
, X
, ConstantInt::get(ShType
, ShiftedC
));
2385 if ((Pred
== ICmpInst::ICMP_EQ
|| Pred
== ICmpInst::ICMP_NE
) &&
2386 C
.ashr(*ShiftAmt
).shl(*ShiftAmt
) == C
) {
2387 APInt ShiftedC
= C
.ashr(*ShiftAmt
);
2388 return new ICmpInst(Pred
, X
, ConstantInt::get(ShType
, ShiftedC
));
2390 if (Pred
== ICmpInst::ICMP_SLT
) {
2391 // SLE is the same as above, but SLE is canonicalized to SLT, so convert:
2392 // (X << S) <=s C is equiv to X <=s (C >> S) for all C
2393 // (X << S) <s (C + 1) is equiv to X <s (C >> S) + 1 if C <s SMAX
2394 // (X << S) <s C is equiv to X <s ((C - 1) >> S) + 1 if C >s SMIN
2395 assert(!C
.isMinSignedValue() && "Unexpected icmp slt");
2396 APInt ShiftedC
= (C
- 1).ashr(*ShiftAmt
) + 1;
2397 return new ICmpInst(Pred
, X
, ConstantInt::get(ShType
, ShiftedC
));
2401 // NUW guarantees that we are only shifting out zero bits from the high bits,
2402 // so we can LSHR the compare constant without needing a mask and eliminate
2404 if (Shl
->hasNoUnsignedWrap()) {
2405 if (Pred
== ICmpInst::ICMP_UGT
) {
2406 // icmp Pred (shl nuw X, ShiftAmt), C --> icmp Pred X, (C >>u ShiftAmt)
2407 APInt ShiftedC
= C
.lshr(*ShiftAmt
);
2408 return new ICmpInst(Pred
, X
, ConstantInt::get(ShType
, ShiftedC
));
2410 if ((Pred
== ICmpInst::ICMP_EQ
|| Pred
== ICmpInst::ICMP_NE
) &&
2411 C
.lshr(*ShiftAmt
).shl(*ShiftAmt
) == C
) {
2412 APInt ShiftedC
= C
.lshr(*ShiftAmt
);
2413 return new ICmpInst(Pred
, X
, ConstantInt::get(ShType
, ShiftedC
));
2415 if (Pred
== ICmpInst::ICMP_ULT
) {
2416 // ULE is the same as above, but ULE is canonicalized to ULT, so convert:
2417 // (X << S) <=u C is equiv to X <=u (C >> S) for all C
2418 // (X << S) <u (C + 1) is equiv to X <u (C >> S) + 1 if C <u ~0u
2419 // (X << S) <u C is equiv to X <u ((C - 1) >> S) + 1 if C >u 0
2420 assert(C
.ugt(0) && "ult 0 should have been eliminated");
2421 APInt ShiftedC
= (C
- 1).lshr(*ShiftAmt
) + 1;
2422 return new ICmpInst(Pred
, X
, ConstantInt::get(ShType
, ShiftedC
));
2426 if (Cmp
.isEquality() && Shl
->hasOneUse()) {
2427 // Strength-reduce the shift into an 'and'.
2428 Constant
*Mask
= ConstantInt::get(
2430 APInt::getLowBitsSet(TypeBits
, TypeBits
- ShiftAmt
->getZExtValue()));
2431 Value
*And
= Builder
.CreateAnd(X
, Mask
, Shl
->getName() + ".mask");
2432 Constant
*LShrC
= ConstantInt::get(ShType
, C
.lshr(*ShiftAmt
));
2433 return new ICmpInst(Pred
, And
, LShrC
);
2436 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
2437 bool TrueIfSigned
= false;
2438 if (Shl
->hasOneUse() && isSignBitCheck(Pred
, C
, TrueIfSigned
)) {
2439 // (X << 31) <s 0 --> (X & 1) != 0
2440 Constant
*Mask
= ConstantInt::get(
2442 APInt::getOneBitSet(TypeBits
, TypeBits
- ShiftAmt
->getZExtValue() - 1));
2443 Value
*And
= Builder
.CreateAnd(X
, Mask
, Shl
->getName() + ".mask");
2444 return new ICmpInst(TrueIfSigned
? ICmpInst::ICMP_NE
: ICmpInst::ICMP_EQ
,
2445 And
, Constant::getNullValue(ShType
));
2448 // Simplify 'shl' inequality test into 'and' equality test.
2449 if (Cmp
.isUnsigned() && Shl
->hasOneUse()) {
2450 // (X l<< C2) u<=/u> C1 iff C1+1 is power of two -> X & (~C1 l>> C2) ==/!= 0
2451 if ((C
+ 1).isPowerOf2() &&
2452 (Pred
== ICmpInst::ICMP_ULE
|| Pred
== ICmpInst::ICMP_UGT
)) {
2453 Value
*And
= Builder
.CreateAnd(X
, (~C
).lshr(ShiftAmt
->getZExtValue()));
2454 return new ICmpInst(Pred
== ICmpInst::ICMP_ULE
? ICmpInst::ICMP_EQ
2455 : ICmpInst::ICMP_NE
,
2456 And
, Constant::getNullValue(ShType
));
2458 // (X l<< C2) u</u>= C1 iff C1 is power of two -> X & (-C1 l>> C2) ==/!= 0
2459 if (C
.isPowerOf2() &&
2460 (Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_UGE
)) {
2462 Builder
.CreateAnd(X
, (~(C
- 1)).lshr(ShiftAmt
->getZExtValue()));
2463 return new ICmpInst(Pred
== ICmpInst::ICMP_ULT
? ICmpInst::ICMP_EQ
2464 : ICmpInst::ICMP_NE
,
2465 And
, Constant::getNullValue(ShType
));
2469 // Transform (icmp pred iM (shl iM %v, N), C)
2470 // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N))
2471 // Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N.
2472 // This enables us to get rid of the shift in favor of a trunc that may be
2473 // free on the target. It has the additional benefit of comparing to a
2474 // smaller constant that may be more target-friendly.
2475 unsigned Amt
= ShiftAmt
->getLimitedValue(TypeBits
- 1);
2476 if (Shl
->hasOneUse() && Amt
!= 0 &&
2477 shouldChangeType(ShType
->getScalarSizeInBits(), TypeBits
- Amt
)) {
2478 ICmpInst::Predicate CmpPred
= Pred
;
2481 if (RHSC
.countr_zero() < Amt
&& ICmpInst::isStrictPredicate(CmpPred
)) {
2482 // Try the flipped strictness predicate.
2484 // icmp ult i64 (shl X, 32), 8589934593 ->
2485 // icmp ule i64 (shl X, 32), 8589934592 ->
2486 // icmp ule i32 (trunc X, i32), 2 ->
2487 // icmp ult i32 (trunc X, i32), 3
2488 if (auto FlippedStrictness
=
2489 InstCombiner::getFlippedStrictnessPredicateAndConstant(
2490 Pred
, ConstantInt::get(ShType
->getContext(), C
))) {
2491 CmpPred
= FlippedStrictness
->first
;
2492 RHSC
= cast
<ConstantInt
>(FlippedStrictness
->second
)->getValue();
2496 if (RHSC
.countr_zero() >= Amt
) {
2497 Type
*TruncTy
= ShType
->getWithNewBitWidth(TypeBits
- Amt
);
2499 ConstantInt::get(TruncTy
, RHSC
.ashr(*ShiftAmt
).trunc(TypeBits
- Amt
));
2500 return new ICmpInst(CmpPred
,
2501 Builder
.CreateTrunc(X
, TruncTy
, "", /*IsNUW=*/false,
2502 Shl
->hasNoSignedWrap()),
2510 /// Fold icmp ({al}shr X, Y), C.
2511 Instruction
*InstCombinerImpl::foldICmpShrConstant(ICmpInst
&Cmp
,
2512 BinaryOperator
*Shr
,
2514 // An exact shr only shifts out zero bits, so:
2515 // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0
2516 Value
*X
= Shr
->getOperand(0);
2517 CmpInst::Predicate Pred
= Cmp
.getPredicate();
2518 if (Cmp
.isEquality() && Shr
->isExact() && C
.isZero())
2519 return new ICmpInst(Pred
, X
, Cmp
.getOperand(1));
2521 bool IsAShr
= Shr
->getOpcode() == Instruction::AShr
;
2522 const APInt
*ShiftValC
;
2523 if (match(X
, m_APInt(ShiftValC
))) {
2524 if (Cmp
.isEquality())
2525 return foldICmpShrConstConst(Cmp
, Shr
->getOperand(1), C
, *ShiftValC
);
2527 // (ShiftValC >> Y) >s -1 --> Y != 0 with ShiftValC < 0
2528 // (ShiftValC >> Y) <s 0 --> Y == 0 with ShiftValC < 0
2530 if (!IsAShr
&& ShiftValC
->isNegative() &&
2531 isSignBitCheck(Pred
, C
, TrueIfSigned
))
2532 return new ICmpInst(TrueIfSigned
? CmpInst::ICMP_EQ
: CmpInst::ICMP_NE
,
2534 ConstantInt::getNullValue(X
->getType()));
2536 // If the shifted constant is a power-of-2, test the shift amount directly:
2537 // (ShiftValC >> Y) >u C --> X <u (LZ(C) - LZ(ShiftValC))
2538 // (ShiftValC >> Y) <u C --> X >=u (LZ(C-1) - LZ(ShiftValC))
2539 if (!IsAShr
&& ShiftValC
->isPowerOf2() &&
2540 (Pred
== CmpInst::ICMP_UGT
|| Pred
== CmpInst::ICMP_ULT
)) {
2541 bool IsUGT
= Pred
== CmpInst::ICMP_UGT
;
2542 assert(ShiftValC
->uge(C
) && "Expected simplify of compare");
2543 assert((IsUGT
|| !C
.isZero()) && "Expected X u< 0 to simplify");
2545 unsigned CmpLZ
= IsUGT
? C
.countl_zero() : (C
- 1).countl_zero();
2546 unsigned ShiftLZ
= ShiftValC
->countl_zero();
2547 Constant
*NewC
= ConstantInt::get(Shr
->getType(), CmpLZ
- ShiftLZ
);
2548 auto NewPred
= IsUGT
? CmpInst::ICMP_ULT
: CmpInst::ICMP_UGE
;
2549 return new ICmpInst(NewPred
, Shr
->getOperand(1), NewC
);
2553 const APInt
*ShiftAmtC
;
2554 if (!match(Shr
->getOperand(1), m_APInt(ShiftAmtC
)))
2557 // Check that the shift amount is in range. If not, don't perform undefined
2558 // shifts. When the shift is visited it will be simplified.
2559 unsigned TypeBits
= C
.getBitWidth();
2560 unsigned ShAmtVal
= ShiftAmtC
->getLimitedValue(TypeBits
);
2561 if (ShAmtVal
>= TypeBits
|| ShAmtVal
== 0)
2564 bool IsExact
= Shr
->isExact();
2565 Type
*ShrTy
= Shr
->getType();
2566 // TODO: If we could guarantee that InstSimplify would handle all of the
2567 // constant-value-based preconditions in the folds below, then we could assert
2568 // those conditions rather than checking them. This is difficult because of
2569 // undef/poison (PR34838).
2570 if (IsAShr
&& Shr
->hasOneUse()) {
2571 if (IsExact
&& (Pred
== CmpInst::ICMP_SLT
|| Pred
== CmpInst::ICMP_ULT
) &&
2572 (C
- 1).isPowerOf2() && C
.countLeadingZeros() > ShAmtVal
) {
2573 // When C - 1 is a power of two and the transform can be legally
2574 // performed, prefer this form so the produced constant is close to a
2576 // icmp slt/ult (ashr exact X, ShAmtC), C
2577 // --> icmp slt/ult X, (C - 1) << ShAmtC) + 1
2578 APInt ShiftedC
= (C
- 1).shl(ShAmtVal
) + 1;
2579 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, ShiftedC
));
2581 if (IsExact
|| Pred
== CmpInst::ICMP_SLT
|| Pred
== CmpInst::ICMP_ULT
) {
2582 // When ShAmtC can be shifted losslessly:
2583 // icmp PRED (ashr exact X, ShAmtC), C --> icmp PRED X, (C << ShAmtC)
2584 // icmp slt/ult (ashr X, ShAmtC), C --> icmp slt/ult X, (C << ShAmtC)
2585 APInt ShiftedC
= C
.shl(ShAmtVal
);
2586 if (ShiftedC
.ashr(ShAmtVal
) == C
)
2587 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, ShiftedC
));
2589 if (Pred
== CmpInst::ICMP_SGT
) {
2590 // icmp sgt (ashr X, ShAmtC), C --> icmp sgt X, ((C + 1) << ShAmtC) - 1
2591 APInt ShiftedC
= (C
+ 1).shl(ShAmtVal
) - 1;
2592 if (!C
.isMaxSignedValue() && !(C
+ 1).shl(ShAmtVal
).isMinSignedValue() &&
2593 (ShiftedC
+ 1).ashr(ShAmtVal
) == (C
+ 1))
2594 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, ShiftedC
));
2596 if (Pred
== CmpInst::ICMP_UGT
) {
2597 // icmp ugt (ashr X, ShAmtC), C --> icmp ugt X, ((C + 1) << ShAmtC) - 1
2598 // 'C + 1 << ShAmtC' can overflow as a signed number, so the 2nd
2599 // clause accounts for that pattern.
2600 APInt ShiftedC
= (C
+ 1).shl(ShAmtVal
) - 1;
2601 if ((ShiftedC
+ 1).ashr(ShAmtVal
) == (C
+ 1) ||
2602 (C
+ 1).shl(ShAmtVal
).isMinSignedValue())
2603 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, ShiftedC
));
2606 // If the compare constant has significant bits above the lowest sign-bit,
2607 // then convert an unsigned cmp to a test of the sign-bit:
2608 // (ashr X, ShiftC) u> C --> X s< 0
2609 // (ashr X, ShiftC) u< C --> X s> -1
2610 if (C
.getBitWidth() > 2 && C
.getNumSignBits() <= ShAmtVal
) {
2611 if (Pred
== CmpInst::ICMP_UGT
) {
2612 return new ICmpInst(CmpInst::ICMP_SLT
, X
,
2613 ConstantInt::getNullValue(ShrTy
));
2615 if (Pred
== CmpInst::ICMP_ULT
) {
2616 return new ICmpInst(CmpInst::ICMP_SGT
, X
,
2617 ConstantInt::getAllOnesValue(ShrTy
));
2620 } else if (!IsAShr
) {
2621 if (Pred
== CmpInst::ICMP_ULT
|| (Pred
== CmpInst::ICMP_UGT
&& IsExact
)) {
2622 // icmp ult (lshr X, ShAmtC), C --> icmp ult X, (C << ShAmtC)
2623 // icmp ugt (lshr exact X, ShAmtC), C --> icmp ugt X, (C << ShAmtC)
2624 APInt ShiftedC
= C
.shl(ShAmtVal
);
2625 if (ShiftedC
.lshr(ShAmtVal
) == C
)
2626 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, ShiftedC
));
2628 if (Pred
== CmpInst::ICMP_UGT
) {
2629 // icmp ugt (lshr X, ShAmtC), C --> icmp ugt X, ((C + 1) << ShAmtC) - 1
2630 APInt ShiftedC
= (C
+ 1).shl(ShAmtVal
) - 1;
2631 if ((ShiftedC
+ 1).lshr(ShAmtVal
) == (C
+ 1))
2632 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, ShiftedC
));
2636 if (!Cmp
.isEquality())
2639 // Handle equality comparisons of shift-by-constant.
2641 // If the comparison constant changes with the shift, the comparison cannot
2642 // succeed (bits of the comparison constant cannot match the shifted value).
2643 // This should be known by InstSimplify and already be folded to true/false.
2644 assert(((IsAShr
&& C
.shl(ShAmtVal
).ashr(ShAmtVal
) == C
) ||
2645 (!IsAShr
&& C
.shl(ShAmtVal
).lshr(ShAmtVal
) == C
)) &&
2646 "Expected icmp+shr simplify did not occur.");
2648 // If the bits shifted out are known zero, compare the unshifted value:
2649 // (X & 4) >> 1 == 2 --> (X & 4) == 4.
2651 return new ICmpInst(Pred
, X
, ConstantInt::get(ShrTy
, C
<< ShAmtVal
));
2655 if (Pred
== CmpInst::ICMP_EQ
)
2656 return new ICmpInst(CmpInst::ICMP_ULT
, X
,
2657 ConstantInt::get(ShrTy
, (C
+ 1).shl(ShAmtVal
)));
2659 return new ICmpInst(CmpInst::ICMP_UGT
, X
,
2660 ConstantInt::get(ShrTy
, (C
+ 1).shl(ShAmtVal
) - 1));
2663 if (Shr
->hasOneUse()) {
2664 // Canonicalize the shift into an 'and':
2665 // icmp eq/ne (shr X, ShAmt), C --> icmp eq/ne (and X, HiMask), (C << ShAmt)
2666 APInt
Val(APInt::getHighBitsSet(TypeBits
, TypeBits
- ShAmtVal
));
2667 Constant
*Mask
= ConstantInt::get(ShrTy
, Val
);
2668 Value
*And
= Builder
.CreateAnd(X
, Mask
, Shr
->getName() + ".mask");
2669 return new ICmpInst(Pred
, And
, ConstantInt::get(ShrTy
, C
<< ShAmtVal
));
2675 Instruction
*InstCombinerImpl::foldICmpSRemConstant(ICmpInst
&Cmp
,
2676 BinaryOperator
*SRem
,
2678 // Match an 'is positive' or 'is negative' comparison of remainder by a
2679 // constant power-of-2 value:
2680 // (X % pow2C) sgt/slt 0
2681 const ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2682 if (Pred
!= ICmpInst::ICMP_SGT
&& Pred
!= ICmpInst::ICMP_SLT
&&
2683 Pred
!= ICmpInst::ICMP_EQ
&& Pred
!= ICmpInst::ICMP_NE
)
2686 // TODO: The one-use check is standard because we do not typically want to
2687 // create longer instruction sequences, but this might be a special-case
2688 // because srem is not good for analysis or codegen.
2689 if (!SRem
->hasOneUse())
2692 const APInt
*DivisorC
;
2693 if (!match(SRem
->getOperand(1), m_Power2(DivisorC
)))
2696 // For cmp_sgt/cmp_slt only zero valued C is handled.
2697 // For cmp_eq/cmp_ne only positive valued C is handled.
2698 if (((Pred
== ICmpInst::ICMP_SGT
|| Pred
== ICmpInst::ICMP_SLT
) &&
2700 ((Pred
== ICmpInst::ICMP_EQ
|| Pred
== ICmpInst::ICMP_NE
) &&
2701 !C
.isStrictlyPositive()))
2704 // Mask off the sign bit and the modulo bits (low-bits).
2705 Type
*Ty
= SRem
->getType();
2706 APInt SignMask
= APInt::getSignMask(Ty
->getScalarSizeInBits());
2707 Constant
*MaskC
= ConstantInt::get(Ty
, SignMask
| (*DivisorC
- 1));
2708 Value
*And
= Builder
.CreateAnd(SRem
->getOperand(0), MaskC
);
2710 if (Pred
== ICmpInst::ICMP_EQ
|| Pred
== ICmpInst::ICMP_NE
)
2711 return new ICmpInst(Pred
, And
, ConstantInt::get(Ty
, C
));
2713 // For 'is positive?' check that the sign-bit is clear and at least 1 masked
2714 // bit is set. Example:
2715 // (i8 X % 32) s> 0 --> (X & 159) s> 0
2716 if (Pred
== ICmpInst::ICMP_SGT
)
2717 return new ICmpInst(ICmpInst::ICMP_SGT
, And
, ConstantInt::getNullValue(Ty
));
2719 // For 'is negative?' check that the sign-bit is set and at least 1 masked
2720 // bit is set. Example:
2721 // (i16 X % 4) s< 0 --> (X & 32771) u> 32768
2722 return new ICmpInst(ICmpInst::ICMP_UGT
, And
, ConstantInt::get(Ty
, SignMask
));
2725 /// Fold icmp (udiv X, Y), C.
2726 Instruction
*InstCombinerImpl::foldICmpUDivConstant(ICmpInst
&Cmp
,
2727 BinaryOperator
*UDiv
,
2729 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2730 Value
*X
= UDiv
->getOperand(0);
2731 Value
*Y
= UDiv
->getOperand(1);
2732 Type
*Ty
= UDiv
->getType();
2735 if (!match(X
, m_APInt(C2
)))
2738 assert(*C2
!= 0 && "udiv 0, X should have been simplified already.");
2740 // (icmp ugt (udiv C2, Y), C) -> (icmp ule Y, C2/(C+1))
2741 if (Pred
== ICmpInst::ICMP_UGT
) {
2742 assert(!C
.isMaxValue() &&
2743 "icmp ugt X, UINT_MAX should have been simplified already.");
2744 return new ICmpInst(ICmpInst::ICMP_ULE
, Y
,
2745 ConstantInt::get(Ty
, C2
->udiv(C
+ 1)));
2748 // (icmp ult (udiv C2, Y), C) -> (icmp ugt Y, C2/C)
2749 if (Pred
== ICmpInst::ICMP_ULT
) {
2750 assert(C
!= 0 && "icmp ult X, 0 should have been simplified already.");
2751 return new ICmpInst(ICmpInst::ICMP_UGT
, Y
,
2752 ConstantInt::get(Ty
, C2
->udiv(C
)));
2758 /// Fold icmp ({su}div X, Y), C.
2759 Instruction
*InstCombinerImpl::foldICmpDivConstant(ICmpInst
&Cmp
,
2760 BinaryOperator
*Div
,
2762 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2763 Value
*X
= Div
->getOperand(0);
2764 Value
*Y
= Div
->getOperand(1);
2765 Type
*Ty
= Div
->getType();
2766 bool DivIsSigned
= Div
->getOpcode() == Instruction::SDiv
;
2768 // If unsigned division and the compare constant is bigger than
2769 // UMAX/2 (negative), there's only one pair of values that satisfies an
2770 // equality check, so eliminate the division:
2771 // (X u/ Y) == C --> (X == C) && (Y == 1)
2772 // (X u/ Y) != C --> (X != C) || (Y != 1)
2773 // Similarly, if signed division and the compare constant is exactly SMIN:
2774 // (X s/ Y) == SMIN --> (X == SMIN) && (Y == 1)
2775 // (X s/ Y) != SMIN --> (X != SMIN) || (Y != 1)
2776 if (Cmp
.isEquality() && Div
->hasOneUse() && C
.isSignBitSet() &&
2777 (!DivIsSigned
|| C
.isMinSignedValue())) {
2778 Value
*XBig
= Builder
.CreateICmp(Pred
, X
, ConstantInt::get(Ty
, C
));
2779 Value
*YOne
= Builder
.CreateICmp(Pred
, Y
, ConstantInt::get(Ty
, 1));
2780 auto Logic
= Pred
== ICmpInst::ICMP_EQ
? Instruction::And
: Instruction::Or
;
2781 return BinaryOperator::Create(Logic
, XBig
, YOne
);
2784 // Fold: icmp pred ([us]div X, C2), C -> range test
2785 // Fold this div into the comparison, producing a range check.
2786 // Determine, based on the divide type, what the range is being
2787 // checked. If there is an overflow on the low or high side, remember
2788 // it, otherwise compute the range [low, hi) bounding the new value.
2789 // See: InsertRangeTest above for the kinds of replacements possible.
2791 if (!match(Y
, m_APInt(C2
)))
2794 // FIXME: If the operand types don't match the type of the divide
2795 // then don't attempt this transform. The code below doesn't have the
2796 // logic to deal with a signed divide and an unsigned compare (and
2797 // vice versa). This is because (x /s C2) <s C produces different
2798 // results than (x /s C2) <u C or (x /u C2) <s C or even
2799 // (x /u C2) <u C. Simply casting the operands and result won't
2800 // work. :( The if statement below tests that condition and bails
2802 if (!Cmp
.isEquality() && DivIsSigned
!= Cmp
.isSigned())
2805 // The ProdOV computation fails on divide by 0 and divide by -1. Cases with
2806 // INT_MIN will also fail if the divisor is 1. Although folds of all these
2807 // division-by-constant cases should be present, we can not assert that they
2808 // have happened before we reach this icmp instruction.
2809 if (C2
->isZero() || C2
->isOne() || (DivIsSigned
&& C2
->isAllOnes()))
2812 // Compute Prod = C * C2. We are essentially solving an equation of
2813 // form X / C2 = C. We solve for X by multiplying C2 and C.
2814 // By solving for X, we can turn this into a range check instead of computing
2816 APInt Prod
= C
* *C2
;
2818 // Determine if the product overflows by seeing if the product is not equal to
2819 // the divide. Make sure we do the same kind of divide as in the LHS
2820 // instruction that we're folding.
2821 bool ProdOV
= (DivIsSigned
? Prod
.sdiv(*C2
) : Prod
.udiv(*C2
)) != C
;
2823 // If the division is known to be exact, then there is no remainder from the
2824 // divide, so the covered range size is unit, otherwise it is the divisor.
2825 APInt RangeSize
= Div
->isExact() ? APInt(C2
->getBitWidth(), 1) : *C2
;
2827 // Figure out the interval that is being checked. For example, a comparison
2828 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
2829 // Compute this interval based on the constants involved and the signedness of
2830 // the compare/divide. This computes a half-open interval, keeping track of
2831 // whether either value in the interval overflows. After analysis each
2832 // overflow variable is set to 0 if it's corresponding bound variable is valid
2833 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
2834 int LoOverflow
= 0, HiOverflow
= 0;
2835 APInt LoBound
, HiBound
;
2837 if (!DivIsSigned
) { // udiv
2838 // e.g. X/5 op 3 --> [15, 20)
2840 HiOverflow
= LoOverflow
= ProdOV
;
2842 // If this is not an exact divide, then many values in the range collapse
2843 // to the same result value.
2844 HiOverflow
= addWithOverflow(HiBound
, LoBound
, RangeSize
, false);
2846 } else if (C2
->isStrictlyPositive()) { // Divisor is > 0.
2847 if (C
.isZero()) { // (X / pos) op 0
2848 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
2849 LoBound
= -(RangeSize
- 1);
2850 HiBound
= RangeSize
;
2851 } else if (C
.isStrictlyPositive()) { // (X / pos) op pos
2852 LoBound
= Prod
; // e.g. X/5 op 3 --> [15, 20)
2853 HiOverflow
= LoOverflow
= ProdOV
;
2855 HiOverflow
= addWithOverflow(HiBound
, Prod
, RangeSize
, true);
2856 } else { // (X / pos) op neg
2857 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
2859 LoOverflow
= HiOverflow
= ProdOV
? -1 : 0;
2861 APInt DivNeg
= -RangeSize
;
2862 LoOverflow
= addWithOverflow(LoBound
, HiBound
, DivNeg
, true) ? -1 : 0;
2865 } else if (C2
->isNegative()) { // Divisor is < 0.
2868 if (C
.isZero()) { // (X / neg) op 0
2869 // e.g. X/-5 op 0 --> [-4, 5)
2870 LoBound
= RangeSize
+ 1;
2871 HiBound
= -RangeSize
;
2872 if (HiBound
== *C2
) { // -INTMIN = INTMIN
2873 HiOverflow
= 1; // [INTMIN+1, overflow)
2874 HiBound
= APInt(); // e.g. X/INTMIN = 0 --> X > INTMIN
2876 } else if (C
.isStrictlyPositive()) { // (X / neg) op pos
2877 // e.g. X/-5 op 3 --> [-19, -14)
2879 HiOverflow
= LoOverflow
= ProdOV
? -1 : 0;
2882 addWithOverflow(LoBound
, HiBound
, RangeSize
, true) ? -1 : 0;
2883 } else { // (X / neg) op neg
2884 LoBound
= Prod
; // e.g. X/-5 op -3 --> [15, 20)
2885 LoOverflow
= HiOverflow
= ProdOV
;
2887 HiOverflow
= subWithOverflow(HiBound
, Prod
, RangeSize
, true);
2890 // Dividing by a negative swaps the condition. LT <-> GT
2891 Pred
= ICmpInst::getSwappedPredicate(Pred
);
2896 llvm_unreachable("Unhandled icmp predicate!");
2897 case ICmpInst::ICMP_EQ
:
2898 if (LoOverflow
&& HiOverflow
)
2899 return replaceInstUsesWith(Cmp
, Builder
.getFalse());
2901 return new ICmpInst(DivIsSigned
? ICmpInst::ICMP_SGE
: ICmpInst::ICMP_UGE
,
2902 X
, ConstantInt::get(Ty
, LoBound
));
2904 return new ICmpInst(DivIsSigned
? ICmpInst::ICMP_SLT
: ICmpInst::ICMP_ULT
,
2905 X
, ConstantInt::get(Ty
, HiBound
));
2906 return replaceInstUsesWith(
2907 Cmp
, insertRangeTest(X
, LoBound
, HiBound
, DivIsSigned
, true));
2908 case ICmpInst::ICMP_NE
:
2909 if (LoOverflow
&& HiOverflow
)
2910 return replaceInstUsesWith(Cmp
, Builder
.getTrue());
2912 return new ICmpInst(DivIsSigned
? ICmpInst::ICMP_SLT
: ICmpInst::ICMP_ULT
,
2913 X
, ConstantInt::get(Ty
, LoBound
));
2915 return new ICmpInst(DivIsSigned
? ICmpInst::ICMP_SGE
: ICmpInst::ICMP_UGE
,
2916 X
, ConstantInt::get(Ty
, HiBound
));
2917 return replaceInstUsesWith(
2918 Cmp
, insertRangeTest(X
, LoBound
, HiBound
, DivIsSigned
, false));
2919 case ICmpInst::ICMP_ULT
:
2920 case ICmpInst::ICMP_SLT
:
2921 if (LoOverflow
== +1) // Low bound is greater than input range.
2922 return replaceInstUsesWith(Cmp
, Builder
.getTrue());
2923 if (LoOverflow
== -1) // Low bound is less than input range.
2924 return replaceInstUsesWith(Cmp
, Builder
.getFalse());
2925 return new ICmpInst(Pred
, X
, ConstantInt::get(Ty
, LoBound
));
2926 case ICmpInst::ICMP_UGT
:
2927 case ICmpInst::ICMP_SGT
:
2928 if (HiOverflow
== +1) // High bound greater than input range.
2929 return replaceInstUsesWith(Cmp
, Builder
.getFalse());
2930 if (HiOverflow
== -1) // High bound less than input range.
2931 return replaceInstUsesWith(Cmp
, Builder
.getTrue());
2932 if (Pred
== ICmpInst::ICMP_UGT
)
2933 return new ICmpInst(ICmpInst::ICMP_UGE
, X
, ConstantInt::get(Ty
, HiBound
));
2934 return new ICmpInst(ICmpInst::ICMP_SGE
, X
, ConstantInt::get(Ty
, HiBound
));
2940 /// Fold icmp (sub X, Y), C.
2941 Instruction
*InstCombinerImpl::foldICmpSubConstant(ICmpInst
&Cmp
,
2942 BinaryOperator
*Sub
,
2944 Value
*X
= Sub
->getOperand(0), *Y
= Sub
->getOperand(1);
2945 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
2946 Type
*Ty
= Sub
->getType();
2948 // (SubC - Y) == C) --> Y == (SubC - C)
2949 // (SubC - Y) != C) --> Y != (SubC - C)
2951 if (Cmp
.isEquality() && match(X
, m_ImmConstant(SubC
))) {
2952 return new ICmpInst(Pred
, Y
,
2953 ConstantExpr::getSub(SubC
, ConstantInt::get(Ty
, C
)));
2956 // (icmp P (sub nuw|nsw C2, Y), C) -> (icmp swap(P) Y, C2-C)
2959 ICmpInst::Predicate SwappedPred
= Cmp
.getSwappedPredicate();
2960 bool HasNSW
= Sub
->hasNoSignedWrap();
2961 bool HasNUW
= Sub
->hasNoUnsignedWrap();
2962 if (match(X
, m_APInt(C2
)) &&
2963 ((Cmp
.isUnsigned() && HasNUW
) || (Cmp
.isSigned() && HasNSW
)) &&
2964 !subWithOverflow(SubResult
, *C2
, C
, Cmp
.isSigned()))
2965 return new ICmpInst(SwappedPred
, Y
, ConstantInt::get(Ty
, SubResult
));
2967 // X - Y == 0 --> X == Y.
2968 // X - Y != 0 --> X != Y.
2969 // TODO: We allow this with multiple uses as long as the other uses are not
2970 // in phis. The phi use check is guarding against a codegen regression
2971 // for a loop test. If the backend could undo this (and possibly
2972 // subsequent transforms), we would not need this hack.
2973 if (Cmp
.isEquality() && C
.isZero() &&
2974 none_of((Sub
->users()), [](const User
*U
) { return isa
<PHINode
>(U
); }))
2975 return new ICmpInst(Pred
, X
, Y
);
2977 // The following transforms are only worth it if the only user of the subtract
2979 // TODO: This is an artificial restriction for all of the transforms below
2980 // that only need a single replacement icmp. Can these use the phi test
2981 // like the transform above here?
2982 if (!Sub
->hasOneUse())
2985 if (Sub
->hasNoSignedWrap()) {
2986 // (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y)
2987 if (Pred
== ICmpInst::ICMP_SGT
&& C
.isAllOnes())
2988 return new ICmpInst(ICmpInst::ICMP_SGE
, X
, Y
);
2990 // (icmp sgt (sub nsw X, Y), 0) -> (icmp sgt X, Y)
2991 if (Pred
== ICmpInst::ICMP_SGT
&& C
.isZero())
2992 return new ICmpInst(ICmpInst::ICMP_SGT
, X
, Y
);
2994 // (icmp slt (sub nsw X, Y), 0) -> (icmp slt X, Y)
2995 if (Pred
== ICmpInst::ICMP_SLT
&& C
.isZero())
2996 return new ICmpInst(ICmpInst::ICMP_SLT
, X
, Y
);
2998 // (icmp slt (sub nsw X, Y), 1) -> (icmp sle X, Y)
2999 if (Pred
== ICmpInst::ICMP_SLT
&& C
.isOne())
3000 return new ICmpInst(ICmpInst::ICMP_SLE
, X
, Y
);
3003 if (!match(X
, m_APInt(C2
)))
3006 // C2 - Y <u C -> (Y | (C - 1)) == C2
3007 // iff (C2 & (C - 1)) == C - 1 and C is a power of 2
3008 if (Pred
== ICmpInst::ICMP_ULT
&& C
.isPowerOf2() &&
3009 (*C2
& (C
- 1)) == (C
- 1))
3010 return new ICmpInst(ICmpInst::ICMP_EQ
, Builder
.CreateOr(Y
, C
- 1), X
);
3012 // C2 - Y >u C -> (Y | C) != C2
3013 // iff C2 & C == C and C + 1 is a power of 2
3014 if (Pred
== ICmpInst::ICMP_UGT
&& (C
+ 1).isPowerOf2() && (*C2
& C
) == C
)
3015 return new ICmpInst(ICmpInst::ICMP_NE
, Builder
.CreateOr(Y
, C
), X
);
3017 // We have handled special cases that reduce.
3018 // Canonicalize any remaining sub to add as:
3019 // (C2 - Y) > C --> (Y + ~C2) < ~C
3020 Value
*Add
= Builder
.CreateAdd(Y
, ConstantInt::get(Ty
, ~(*C2
)), "notsub",
3022 return new ICmpInst(SwappedPred
, Add
, ConstantInt::get(Ty
, ~C
));
3025 static Value
*createLogicFromTable(const std::bitset
<4> &Table
, Value
*Op0
,
3026 Value
*Op1
, IRBuilderBase
&Builder
,
3028 auto FoldConstant
= [&](bool Val
) {
3029 Constant
*Res
= Val
? Builder
.getTrue() : Builder
.getFalse();
3030 if (Op0
->getType()->isVectorTy())
3031 Res
= ConstantVector::getSplat(
3032 cast
<VectorType
>(Op0
->getType())->getElementCount(), Res
);
3036 switch (Table
.to_ulong()) {
3038 return FoldConstant(false);
3040 return HasOneUse
? Builder
.CreateNot(Builder
.CreateOr(Op0
, Op1
)) : nullptr;
3042 return HasOneUse
? Builder
.CreateAnd(Builder
.CreateNot(Op0
), Op1
) : nullptr;
3044 return Builder
.CreateNot(Op0
);
3046 return HasOneUse
? Builder
.CreateAnd(Op0
, Builder
.CreateNot(Op1
)) : nullptr;
3048 return Builder
.CreateNot(Op1
);
3050 return Builder
.CreateXor(Op0
, Op1
);
3052 return HasOneUse
? Builder
.CreateNot(Builder
.CreateAnd(Op0
, Op1
)) : nullptr;
3054 return Builder
.CreateAnd(Op0
, Op1
);
3056 return HasOneUse
? Builder
.CreateNot(Builder
.CreateXor(Op0
, Op1
)) : nullptr;
3060 return HasOneUse
? Builder
.CreateOr(Builder
.CreateNot(Op0
), Op1
) : nullptr;
3064 return HasOneUse
? Builder
.CreateOr(Op0
, Builder
.CreateNot(Op1
)) : nullptr;
3066 return Builder
.CreateOr(Op0
, Op1
);
3068 return FoldConstant(true);
3070 llvm_unreachable("Invalid Operation");
3075 /// Fold icmp (add X, Y), C.
3076 Instruction
*InstCombinerImpl::foldICmpAddConstant(ICmpInst
&Cmp
,
3077 BinaryOperator
*Add
,
3079 Value
*Y
= Add
->getOperand(1);
3080 Value
*X
= Add
->getOperand(0);
3083 Instruction
*Ext0
, *Ext1
;
3084 const CmpInst::Predicate Pred
= Cmp
.getPredicate();
3086 m_Add(m_CombineAnd(m_Instruction(Ext0
), m_ZExtOrSExt(m_Value(Op0
))),
3087 m_CombineAnd(m_Instruction(Ext1
),
3088 m_ZExtOrSExt(m_Value(Op1
))))) &&
3089 Op0
->getType()->isIntOrIntVectorTy(1) &&
3090 Op1
->getType()->isIntOrIntVectorTy(1)) {
3091 unsigned BW
= C
.getBitWidth();
3092 std::bitset
<4> Table
;
3093 auto ComputeTable
= [&](bool Op0Val
, bool Op1Val
) {
3096 Res
+= APInt(BW
, isa
<ZExtInst
>(Ext0
) ? 1 : -1, /*isSigned=*/true);
3098 Res
+= APInt(BW
, isa
<ZExtInst
>(Ext1
) ? 1 : -1, /*isSigned=*/true);
3099 return ICmpInst::compare(Res
, C
, Pred
);
3102 Table
[0] = ComputeTable(false, false);
3103 Table
[1] = ComputeTable(false, true);
3104 Table
[2] = ComputeTable(true, false);
3105 Table
[3] = ComputeTable(true, true);
3107 createLogicFromTable(Table
, Op0
, Op1
, Builder
, Add
->hasOneUse()))
3108 return replaceInstUsesWith(Cmp
, Cond
);
3111 if (Cmp
.isEquality() || !match(Y
, m_APInt(C2
)))
3114 // Fold icmp pred (add X, C2), C.
3115 Type
*Ty
= Add
->getType();
3117 // If the add does not wrap, we can always adjust the compare by subtracting
3118 // the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE
3119 // are canonicalized to SGT/SLT/UGT/ULT.
3120 if ((Add
->hasNoSignedWrap() &&
3121 (Pred
== ICmpInst::ICMP_SGT
|| Pred
== ICmpInst::ICMP_SLT
)) ||
3122 (Add
->hasNoUnsignedWrap() &&
3123 (Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_ULT
))) {
3126 Cmp
.isSigned() ? C
.ssub_ov(*C2
, Overflow
) : C
.usub_ov(*C2
, Overflow
);
3127 // If there is overflow, the result must be true or false.
3128 // TODO: Can we assert there is no overflow because InstSimplify always
3129 // handles those cases?
3131 // icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2)
3132 return new ICmpInst(Pred
, X
, ConstantInt::get(Ty
, NewC
));
3135 if (ICmpInst::isUnsigned(Pred
) && Add
->hasNoSignedWrap() &&
3136 C
.isNonNegative() && (C
- *C2
).isNonNegative() &&
3137 computeConstantRange(X
, /*ForSigned=*/true).add(*C2
).isAllNonNegative())
3138 return new ICmpInst(ICmpInst::getSignedPredicate(Pred
), X
,
3139 ConstantInt::get(Ty
, C
- *C2
));
3141 auto CR
= ConstantRange::makeExactICmpRegion(Pred
, C
).subtract(*C2
);
3142 const APInt
&Upper
= CR
.getUpper();
3143 const APInt
&Lower
= CR
.getLower();
3144 if (Cmp
.isSigned()) {
3145 if (Lower
.isSignMask())
3146 return new ICmpInst(ICmpInst::ICMP_SLT
, X
, ConstantInt::get(Ty
, Upper
));
3147 if (Upper
.isSignMask())
3148 return new ICmpInst(ICmpInst::ICMP_SGE
, X
, ConstantInt::get(Ty
, Lower
));
3150 if (Lower
.isMinValue())
3151 return new ICmpInst(ICmpInst::ICMP_ULT
, X
, ConstantInt::get(Ty
, Upper
));
3152 if (Upper
.isMinValue())
3153 return new ICmpInst(ICmpInst::ICMP_UGE
, X
, ConstantInt::get(Ty
, Lower
));
3156 // This set of folds is intentionally placed after folds that use no-wrapping
3157 // flags because those folds are likely better for later analysis/codegen.
3158 const APInt SMax
= APInt::getSignedMaxValue(Ty
->getScalarSizeInBits());
3159 const APInt SMin
= APInt::getSignedMinValue(Ty
->getScalarSizeInBits());
3161 // Fold compare with offset to opposite sign compare if it eliminates offset:
3162 // (X + C2) >u C --> X <s -C2 (if C == C2 + SMAX)
3163 if (Pred
== CmpInst::ICMP_UGT
&& C
== *C2
+ SMax
)
3164 return new ICmpInst(ICmpInst::ICMP_SLT
, X
, ConstantInt::get(Ty
, -(*C2
)));
3166 // (X + C2) <u C --> X >s ~C2 (if C == C2 + SMIN)
3167 if (Pred
== CmpInst::ICMP_ULT
&& C
== *C2
+ SMin
)
3168 return new ICmpInst(ICmpInst::ICMP_SGT
, X
, ConstantInt::get(Ty
, ~(*C2
)));
3170 // (X + C2) >s C --> X <u (SMAX - C) (if C == C2 - 1)
3171 if (Pred
== CmpInst::ICMP_SGT
&& C
== *C2
- 1)
3172 return new ICmpInst(ICmpInst::ICMP_ULT
, X
, ConstantInt::get(Ty
, SMax
- C
));
3174 // (X + C2) <s C --> X >u (C ^ SMAX) (if C == C2)
3175 if (Pred
== CmpInst::ICMP_SLT
&& C
== *C2
)
3176 return new ICmpInst(ICmpInst::ICMP_UGT
, X
, ConstantInt::get(Ty
, C
^ SMax
));
3178 // (X + -1) <u C --> X <=u C (if X is never null)
3179 if (Pred
== CmpInst::ICMP_ULT
&& C2
->isAllOnes()) {
3180 const SimplifyQuery Q
= SQ
.getWithInstruction(&Cmp
);
3181 if (llvm::isKnownNonZero(X
, Q
))
3182 return new ICmpInst(ICmpInst::ICMP_ULE
, X
, ConstantInt::get(Ty
, C
));
3185 if (!Add
->hasOneUse())
3188 // X+C <u C2 -> (X & -C2) == C
3189 // iff C & (C2-1) == 0
3190 // C2 is a power of 2
3191 if (Pred
== ICmpInst::ICMP_ULT
&& C
.isPowerOf2() && (*C2
& (C
- 1)) == 0)
3192 return new ICmpInst(ICmpInst::ICMP_EQ
, Builder
.CreateAnd(X
, -C
),
3193 ConstantExpr::getNeg(cast
<Constant
>(Y
)));
3195 // X+C2 <u C -> (X & C) == 2C
3197 // C2 is a power of 2
3198 if (Pred
== ICmpInst::ICMP_ULT
&& C2
->isPowerOf2() && C
== -*C2
)
3199 return new ICmpInst(ICmpInst::ICMP_NE
, Builder
.CreateAnd(X
, C
),
3200 ConstantInt::get(Ty
, C
* 2));
3202 // X+C >u C2 -> (X & ~C2) != C
3204 // C2+1 is a power of 2
3205 if (Pred
== ICmpInst::ICMP_UGT
&& (C
+ 1).isPowerOf2() && (*C2
& C
) == 0)
3206 return new ICmpInst(ICmpInst::ICMP_NE
, Builder
.CreateAnd(X
, ~C
),
3207 ConstantExpr::getNeg(cast
<Constant
>(Y
)));
3209 // The range test idiom can use either ult or ugt. Arbitrarily canonicalize
3211 // X+C2 >u C -> X+(C2-C-1) <u ~C
3212 if (Pred
== ICmpInst::ICMP_UGT
)
3213 return new ICmpInst(ICmpInst::ICMP_ULT
,
3214 Builder
.CreateAdd(X
, ConstantInt::get(Ty
, *C2
- C
- 1)),
3215 ConstantInt::get(Ty
, ~C
));
3217 // zext(V) + C2 pred C -> V + C3 pred' C4
3219 if (match(X
, m_ZExt(m_Value(V
)))) {
3220 Type
*NewCmpTy
= V
->getType();
3221 unsigned NewCmpBW
= NewCmpTy
->getScalarSizeInBits();
3222 if (shouldChangeType(Ty
, NewCmpTy
)) {
3223 if (CR
.getActiveBits() <= NewCmpBW
) {
3224 ConstantRange SrcCR
= CR
.truncate(NewCmpBW
);
3225 CmpInst::Predicate EquivPred
;
3229 SrcCR
.getEquivalentICmp(EquivPred
, EquivInt
, EquivOffset
);
3230 return new ICmpInst(
3232 EquivOffset
.isZero()
3234 : Builder
.CreateAdd(V
, ConstantInt::get(NewCmpTy
, EquivOffset
)),
3235 ConstantInt::get(NewCmpTy
, EquivInt
));
3243 bool InstCombinerImpl::matchThreeWayIntCompare(SelectInst
*SI
, Value
*&LHS
,
3244 Value
*&RHS
, ConstantInt
*&Less
,
3245 ConstantInt
*&Equal
,
3246 ConstantInt
*&Greater
) {
3247 // TODO: Generalize this to work with other comparison idioms or ensure
3248 // they get canonicalized into this form.
3250 // select i1 (a == b),
3252 // i32 (select i1 (a < b), i32 Less, i32 Greater)
3253 // where Equal, Less and Greater are placeholders for any three constants.
3255 if (!match(SI
->getCondition(), m_ICmp(PredA
, m_Value(LHS
), m_Value(RHS
))) ||
3256 !ICmpInst::isEquality(PredA
))
3258 Value
*EqualVal
= SI
->getTrueValue();
3259 Value
*UnequalVal
= SI
->getFalseValue();
3260 // We still can get non-canonical predicate here, so canonicalize.
3261 if (PredA
== ICmpInst::ICMP_NE
)
3262 std::swap(EqualVal
, UnequalVal
);
3263 if (!match(EqualVal
, m_ConstantInt(Equal
)))
3267 if (!match(UnequalVal
, m_Select(m_ICmp(PredB
, m_Value(LHS2
), m_Value(RHS2
)),
3268 m_ConstantInt(Less
), m_ConstantInt(Greater
))))
3270 // We can get predicate mismatch here, so canonicalize if possible:
3271 // First, ensure that 'LHS' match.
3273 // x sgt y <--> y slt x
3274 std::swap(LHS2
, RHS2
);
3275 PredB
= ICmpInst::getSwappedPredicate(PredB
);
3279 // We also need to canonicalize 'RHS'.
3280 if (PredB
== ICmpInst::ICMP_SGT
&& isa
<Constant
>(RHS2
)) {
3281 // x sgt C-1 <--> x sge C <--> not(x slt C)
3282 auto FlippedStrictness
=
3283 InstCombiner::getFlippedStrictnessPredicateAndConstant(
3284 PredB
, cast
<Constant
>(RHS2
));
3285 if (!FlippedStrictness
)
3287 assert(FlippedStrictness
->first
== ICmpInst::ICMP_SGE
&&
3288 "basic correctness failure");
3289 RHS2
= FlippedStrictness
->second
;
3290 // And kind-of perform the result swap.
3291 std::swap(Less
, Greater
);
3292 PredB
= ICmpInst::ICMP_SLT
;
3294 return PredB
== ICmpInst::ICMP_SLT
&& RHS
== RHS2
;
3297 Instruction
*InstCombinerImpl::foldICmpSelectConstant(ICmpInst
&Cmp
,
3301 assert(C
&& "Cmp RHS should be a constant int!");
3302 // If we're testing a constant value against the result of a three way
3303 // comparison, the result can be expressed directly in terms of the
3304 // original values being compared. Note: We could possibly be more
3305 // aggressive here and remove the hasOneUse test. The original select is
3306 // really likely to simplify or sink when we remove a test of the result.
3307 Value
*OrigLHS
, *OrigRHS
;
3308 ConstantInt
*C1LessThan
, *C2Equal
, *C3GreaterThan
;
3309 if (Cmp
.hasOneUse() &&
3310 matchThreeWayIntCompare(Select
, OrigLHS
, OrigRHS
, C1LessThan
, C2Equal
,
3312 assert(C1LessThan
&& C2Equal
&& C3GreaterThan
);
3314 bool TrueWhenLessThan
= ICmpInst::compare(
3315 C1LessThan
->getValue(), C
->getValue(), Cmp
.getPredicate());
3316 bool TrueWhenEqual
= ICmpInst::compare(C2Equal
->getValue(), C
->getValue(),
3317 Cmp
.getPredicate());
3318 bool TrueWhenGreaterThan
= ICmpInst::compare(
3319 C3GreaterThan
->getValue(), C
->getValue(), Cmp
.getPredicate());
3321 // This generates the new instruction that will replace the original Cmp
3322 // Instruction. Instead of enumerating the various combinations when
3323 // TrueWhenLessThan, TrueWhenEqual and TrueWhenGreaterThan are true versus
3324 // false, we rely on chaining of ORs and future passes of InstCombine to
3325 // simplify the OR further (i.e. a s< b || a == b becomes a s<= b).
3327 // When none of the three constants satisfy the predicate for the RHS (C),
3328 // the entire original Cmp can be simplified to a false.
3329 Value
*Cond
= Builder
.getFalse();
3330 if (TrueWhenLessThan
)
3331 Cond
= Builder
.CreateOr(Cond
, Builder
.CreateICmp(ICmpInst::ICMP_SLT
,
3334 Cond
= Builder
.CreateOr(Cond
, Builder
.CreateICmp(ICmpInst::ICMP_EQ
,
3336 if (TrueWhenGreaterThan
)
3337 Cond
= Builder
.CreateOr(Cond
, Builder
.CreateICmp(ICmpInst::ICMP_SGT
,
3340 return replaceInstUsesWith(Cmp
, Cond
);
3345 Instruction
*InstCombinerImpl::foldICmpBitCast(ICmpInst
&Cmp
) {
3346 auto *Bitcast
= dyn_cast
<BitCastInst
>(Cmp
.getOperand(0));
3350 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
3351 Value
*Op1
= Cmp
.getOperand(1);
3352 Value
*BCSrcOp
= Bitcast
->getOperand(0);
3353 Type
*SrcType
= Bitcast
->getSrcTy();
3354 Type
*DstType
= Bitcast
->getType();
3356 // Make sure the bitcast doesn't change between scalar and vector and
3357 // doesn't change the number of vector elements.
3358 if (SrcType
->isVectorTy() == DstType
->isVectorTy() &&
3359 SrcType
->getScalarSizeInBits() == DstType
->getScalarSizeInBits()) {
3360 // Zero-equality and sign-bit checks are preserved through sitofp + bitcast.
3362 if (match(BCSrcOp
, m_SIToFP(m_Value(X
)))) {
3363 // icmp eq (bitcast (sitofp X)), 0 --> icmp eq X, 0
3364 // icmp ne (bitcast (sitofp X)), 0 --> icmp ne X, 0
3365 // icmp slt (bitcast (sitofp X)), 0 --> icmp slt X, 0
3366 // icmp sgt (bitcast (sitofp X)), 0 --> icmp sgt X, 0
3367 if ((Pred
== ICmpInst::ICMP_EQ
|| Pred
== ICmpInst::ICMP_SLT
||
3368 Pred
== ICmpInst::ICMP_NE
|| Pred
== ICmpInst::ICMP_SGT
) &&
3369 match(Op1
, m_Zero()))
3370 return new ICmpInst(Pred
, X
, ConstantInt::getNullValue(X
->getType()));
3372 // icmp slt (bitcast (sitofp X)), 1 --> icmp slt X, 1
3373 if (Pred
== ICmpInst::ICMP_SLT
&& match(Op1
, m_One()))
3374 return new ICmpInst(Pred
, X
, ConstantInt::get(X
->getType(), 1));
3376 // icmp sgt (bitcast (sitofp X)), -1 --> icmp sgt X, -1
3377 if (Pred
== ICmpInst::ICMP_SGT
&& match(Op1
, m_AllOnes()))
3378 return new ICmpInst(Pred
, X
,
3379 ConstantInt::getAllOnesValue(X
->getType()));
3382 // Zero-equality checks are preserved through unsigned floating-point casts:
3383 // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0
3384 // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0
3385 if (match(BCSrcOp
, m_UIToFP(m_Value(X
))))
3386 if (Cmp
.isEquality() && match(Op1
, m_Zero()))
3387 return new ICmpInst(Pred
, X
, ConstantInt::getNullValue(X
->getType()));
3391 if (match(Op1
, m_APInt(C
)) && Bitcast
->hasOneUse()) {
3392 // If this is a sign-bit test of a bitcast of a casted FP value, eliminate
3393 // the FP extend/truncate because that cast does not change the sign-bit.
3394 // This is true for all standard IEEE-754 types and the X86 80-bit type.
3395 // The sign-bit is always the most significant bit in those types.
3396 if (isSignBitCheck(Pred
, *C
, TrueIfSigned
) &&
3397 (match(BCSrcOp
, m_FPExt(m_Value(X
))) ||
3398 match(BCSrcOp
, m_FPTrunc(m_Value(X
))))) {
3399 // (bitcast (fpext/fptrunc X)) to iX) < 0 --> (bitcast X to iY) < 0
3400 // (bitcast (fpext/fptrunc X)) to iX) > -1 --> (bitcast X to iY) > -1
3401 Type
*XType
= X
->getType();
3403 // We can't currently handle Power style floating point operations here.
3404 if (!(XType
->isPPC_FP128Ty() || SrcType
->isPPC_FP128Ty())) {
3405 Type
*NewType
= Builder
.getIntNTy(XType
->getScalarSizeInBits());
3406 if (auto *XVTy
= dyn_cast
<VectorType
>(XType
))
3407 NewType
= VectorType::get(NewType
, XVTy
->getElementCount());
3408 Value
*NewBitcast
= Builder
.CreateBitCast(X
, NewType
);
3410 return new ICmpInst(ICmpInst::ICMP_SLT
, NewBitcast
,
3411 ConstantInt::getNullValue(NewType
));
3413 return new ICmpInst(ICmpInst::ICMP_SGT
, NewBitcast
,
3414 ConstantInt::getAllOnesValue(NewType
));
3418 // icmp eq/ne (bitcast X to int), special fp -> llvm.is.fpclass(X, class)
3419 Type
*FPType
= SrcType
->getScalarType();
3420 if (!Cmp
.getParent()->getParent()->hasFnAttribute(
3421 Attribute::NoImplicitFloat
) &&
3422 Cmp
.isEquality() && FPType
->isIEEELikeFPTy()) {
3423 FPClassTest Mask
= APFloat(FPType
->getFltSemantics(), *C
).classify();
3424 if (Mask
& (fcInf
| fcZero
)) {
3425 if (Pred
== ICmpInst::ICMP_NE
)
3427 return replaceInstUsesWith(Cmp
,
3428 Builder
.createIsFPClass(BCSrcOp
, Mask
));
3435 if (!match(Cmp
.getOperand(1), m_APInt(C
)) || !DstType
->isIntegerTy() ||
3436 !SrcType
->isIntOrIntVectorTy())
3439 // If this is checking if all elements of a vector compare are set or not,
3440 // invert the casted vector equality compare and test if all compare
3441 // elements are clear or not. Compare against zero is generally easier for
3442 // analysis and codegen.
3443 // icmp eq/ne (bitcast (not X) to iN), -1 --> icmp eq/ne (bitcast X to iN), 0
3444 // Example: are all elements equal? --> are zero elements not equal?
3445 // TODO: Try harder to reduce compare of 2 freely invertible operands?
3446 if (Cmp
.isEquality() && C
->isAllOnes() && Bitcast
->hasOneUse()) {
3447 if (Value
*NotBCSrcOp
=
3448 getFreelyInverted(BCSrcOp
, BCSrcOp
->hasOneUse(), &Builder
)) {
3449 Value
*Cast
= Builder
.CreateBitCast(NotBCSrcOp
, DstType
);
3450 return new ICmpInst(Pred
, Cast
, ConstantInt::getNullValue(DstType
));
3454 // If this is checking if all elements of an extended vector are clear or not,
3455 // compare in a narrow type to eliminate the extend:
3456 // icmp eq/ne (bitcast (ext X) to iN), 0 --> icmp eq/ne (bitcast X to iM), 0
3458 if (Cmp
.isEquality() && C
->isZero() && Bitcast
->hasOneUse() &&
3459 match(BCSrcOp
, m_ZExtOrSExt(m_Value(X
)))) {
3460 if (auto *VecTy
= dyn_cast
<FixedVectorType
>(X
->getType())) {
3461 Type
*NewType
= Builder
.getIntNTy(VecTy
->getPrimitiveSizeInBits());
3462 Value
*NewCast
= Builder
.CreateBitCast(X
, NewType
);
3463 return new ICmpInst(Pred
, NewCast
, ConstantInt::getNullValue(NewType
));
3467 // Folding: icmp <pred> iN X, C
3468 // where X = bitcast <M x iK> (shufflevector <M x iK> %vec, undef, SC)) to iN
3469 // and C is a splat of a K-bit pattern
3470 // and SC is a constant vector = <C', C', C', ..., C'>
3472 // %E = extractelement <M x iK> %vec, i32 C'
3473 // icmp <pred> iK %E, trunc(C)
3476 if (match(BCSrcOp
, m_Shuffle(m_Value(Vec
), m_Undef(), m_Mask(Mask
)))) {
3477 // Check whether every element of Mask is the same constant
3478 if (all_equal(Mask
)) {
3479 auto *VecTy
= cast
<VectorType
>(SrcType
);
3480 auto *EltTy
= cast
<IntegerType
>(VecTy
->getElementType());
3481 if (C
->isSplat(EltTy
->getBitWidth())) {
3482 // Fold the icmp based on the value of C
3483 // If C is M copies of an iK sized bit pattern,
3485 // => %E = extractelement <N x iK> %vec, i32 Elem
3486 // icmp <pred> iK %SplatVal, <pattern>
3487 Value
*Elem
= Builder
.getInt32(Mask
[0]);
3488 Value
*Extract
= Builder
.CreateExtractElement(Vec
, Elem
);
3489 Value
*NewC
= ConstantInt::get(EltTy
, C
->trunc(EltTy
->getBitWidth()));
3490 return new ICmpInst(Pred
, Extract
, NewC
);
3497 /// Try to fold integer comparisons with a constant operand: icmp Pred X, C
3498 /// where X is some kind of instruction.
3499 Instruction
*InstCombinerImpl::foldICmpInstWithConstant(ICmpInst
&Cmp
) {
3502 if (match(Cmp
.getOperand(1), m_APInt(C
))) {
3503 if (auto *BO
= dyn_cast
<BinaryOperator
>(Cmp
.getOperand(0)))
3504 if (Instruction
*I
= foldICmpBinOpWithConstant(Cmp
, BO
, *C
))
3507 if (auto *SI
= dyn_cast
<SelectInst
>(Cmp
.getOperand(0)))
3508 // For now, we only support constant integers while folding the
3509 // ICMP(SELECT)) pattern. We can extend this to support vector of integers
3510 // similar to the cases handled by binary ops above.
3511 if (auto *ConstRHS
= dyn_cast
<ConstantInt
>(Cmp
.getOperand(1)))
3512 if (Instruction
*I
= foldICmpSelectConstant(Cmp
, SI
, ConstRHS
))
3515 if (auto *TI
= dyn_cast
<TruncInst
>(Cmp
.getOperand(0)))
3516 if (Instruction
*I
= foldICmpTruncConstant(Cmp
, TI
, *C
))
3519 if (auto *II
= dyn_cast
<IntrinsicInst
>(Cmp
.getOperand(0)))
3520 if (Instruction
*I
= foldICmpIntrinsicWithConstant(Cmp
, II
, *C
))
3523 // (extractval ([s/u]subo X, Y), 0) == 0 --> X == Y
3524 // (extractval ([s/u]subo X, Y), 0) != 0 --> X != Y
3525 // TODO: This checks one-use, but that is not strictly necessary.
3526 Value
*Cmp0
= Cmp
.getOperand(0);
3528 if (C
->isZero() && Cmp
.isEquality() && Cmp0
->hasOneUse() &&
3530 m_ExtractValue
<0>(m_Intrinsic
<Intrinsic::ssub_with_overflow
>(
3531 m_Value(X
), m_Value(Y
)))) ||
3533 m_ExtractValue
<0>(m_Intrinsic
<Intrinsic::usub_with_overflow
>(
3534 m_Value(X
), m_Value(Y
))))))
3535 return new ICmpInst(Cmp
.getPredicate(), X
, Y
);
3538 if (match(Cmp
.getOperand(1), m_APIntAllowPoison(C
)))
3539 return foldICmpInstWithConstantAllowPoison(Cmp
, *C
);
3544 /// Fold an icmp equality instruction with binary operator LHS and constant RHS:
3545 /// icmp eq/ne BO, C.
3546 Instruction
*InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
3547 ICmpInst
&Cmp
, BinaryOperator
*BO
, const APInt
&C
) {
3548 // TODO: Some of these folds could work with arbitrary constants, but this
3549 // function is limited to scalar and vector splat constants.
3550 if (!Cmp
.isEquality())
3553 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
3554 bool isICMP_NE
= Pred
== ICmpInst::ICMP_NE
;
3555 Constant
*RHS
= cast
<Constant
>(Cmp
.getOperand(1));
3556 Value
*BOp0
= BO
->getOperand(0), *BOp1
= BO
->getOperand(1);
3558 switch (BO
->getOpcode()) {
3559 case Instruction::SRem
:
3560 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
3561 if (C
.isZero() && BO
->hasOneUse()) {
3563 if (match(BOp1
, m_APInt(BOC
)) && BOC
->sgt(1) && BOC
->isPowerOf2()) {
3564 Value
*NewRem
= Builder
.CreateURem(BOp0
, BOp1
, BO
->getName());
3565 return new ICmpInst(Pred
, NewRem
,
3566 Constant::getNullValue(BO
->getType()));
3570 case Instruction::Add
: {
3571 // (A + C2) == C --> A == (C - C2)
3572 // (A + C2) != C --> A != (C - C2)
3573 // TODO: Remove the one-use limitation? See discussion in D58633.
3574 if (Constant
*C2
= dyn_cast
<Constant
>(BOp1
)) {
3575 if (BO
->hasOneUse())
3576 return new ICmpInst(Pred
, BOp0
, ConstantExpr::getSub(RHS
, C2
));
3577 } else if (C
.isZero()) {
3578 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3579 // efficiently invertible, or if the add has just this one use.
3580 if (Value
*NegVal
= dyn_castNegVal(BOp1
))
3581 return new ICmpInst(Pred
, BOp0
, NegVal
);
3582 if (Value
*NegVal
= dyn_castNegVal(BOp0
))
3583 return new ICmpInst(Pred
, NegVal
, BOp1
);
3584 if (BO
->hasOneUse()) {
3585 // (add nuw A, B) != 0 -> (or A, B) != 0
3586 if (match(BO
, m_NUWAdd(m_Value(), m_Value()))) {
3587 Value
*Or
= Builder
.CreateOr(BOp0
, BOp1
);
3588 return new ICmpInst(Pred
, Or
, Constant::getNullValue(BO
->getType()));
3590 Value
*Neg
= Builder
.CreateNeg(BOp1
);
3592 return new ICmpInst(Pred
, BOp0
, Neg
);
3597 case Instruction::Xor
:
3598 if (Constant
*BOC
= dyn_cast
<Constant
>(BOp1
)) {
3599 // For the xor case, we can xor two constants together, eliminating
3600 // the explicit xor.
3601 return new ICmpInst(Pred
, BOp0
, ConstantExpr::getXor(RHS
, BOC
));
3602 } else if (C
.isZero()) {
3603 // Replace ((xor A, B) != 0) with (A != B)
3604 return new ICmpInst(Pred
, BOp0
, BOp1
);
3607 case Instruction::Or
: {
3609 if (match(BOp1
, m_APInt(BOC
)) && BO
->hasOneUse() && RHS
->isAllOnesValue()) {
3610 // Comparing if all bits outside of a constant mask are set?
3611 // Replace (X | C) == -1 with (X & ~C) == ~C.
3612 // This removes the -1 constant.
3613 Constant
*NotBOC
= ConstantExpr::getNot(cast
<Constant
>(BOp1
));
3614 Value
*And
= Builder
.CreateAnd(BOp0
, NotBOC
);
3615 return new ICmpInst(Pred
, And
, NotBOC
);
3617 // (icmp eq (or (select cond, 0, NonZero), Other), 0)
3618 // -> (and cond, (icmp eq Other, 0))
3619 // (icmp ne (or (select cond, NonZero, 0), Other), 0)
3620 // -> (or cond, (icmp ne Other, 0))
3621 Value
*Cond
, *TV
, *FV
, *Other
, *Sel
;
3624 m_OneUse(m_c_Or(m_CombineAnd(m_Value(Sel
),
3625 m_Select(m_Value(Cond
), m_Value(TV
),
3627 m_Value(Other
)))) &&
3628 Cond
->getType() == Cmp
.getType()) {
3629 const SimplifyQuery Q
= SQ
.getWithInstruction(&Cmp
);
3630 // Easy case is if eq/ne matches whether 0 is trueval/falseval.
3631 if (Pred
== ICmpInst::ICMP_EQ
3632 ? (match(TV
, m_Zero()) && isKnownNonZero(FV
, Q
))
3633 : (match(FV
, m_Zero()) && isKnownNonZero(TV
, Q
))) {
3634 Value
*Cmp
= Builder
.CreateICmp(
3635 Pred
, Other
, Constant::getNullValue(Other
->getType()));
3636 return BinaryOperator::Create(
3637 Pred
== ICmpInst::ICMP_EQ
? Instruction::And
: Instruction::Or
, Cmp
,
3640 // Harder case is if eq/ne matches whether 0 is falseval/trueval. In this
3641 // case we need to invert the select condition so we need to be careful to
3642 // avoid creating extra instructions.
3643 // (icmp ne (or (select cond, 0, NonZero), Other), 0)
3644 // -> (or (not cond), (icmp ne Other, 0))
3645 // (icmp eq (or (select cond, NonZero, 0), Other), 0)
3646 // -> (and (not cond), (icmp eq Other, 0))
3648 // Only do this if the inner select has one use, in which case we are
3649 // replacing `select` with `(not cond)`. Otherwise, we will create more
3650 // uses. NB: Trying to freely invert cond doesn't make sense here, as if
3651 // cond was freely invertable, the select arms would have been inverted.
3652 if (Sel
->hasOneUse() &&
3653 (Pred
== ICmpInst::ICMP_EQ
3654 ? (match(FV
, m_Zero()) && isKnownNonZero(TV
, Q
))
3655 : (match(TV
, m_Zero()) && isKnownNonZero(FV
, Q
)))) {
3656 Value
*NotCond
= Builder
.CreateNot(Cond
);
3657 Value
*Cmp
= Builder
.CreateICmp(
3658 Pred
, Other
, Constant::getNullValue(Other
->getType()));
3659 return BinaryOperator::Create(
3660 Pred
== ICmpInst::ICMP_EQ
? Instruction::And
: Instruction::Or
, Cmp
,
3666 case Instruction::UDiv
:
3667 case Instruction::SDiv
:
3668 if (BO
->isExact()) {
3669 // div exact X, Y eq/ne 0 -> X eq/ne 0
3670 // div exact X, Y eq/ne 1 -> X eq/ne Y
3671 // div exact X, Y eq/ne C ->
3672 // if Y * C never-overflow && OneUse:
3675 return new ICmpInst(Pred
, BOp0
, Constant::getNullValue(BO
->getType()));
3677 return new ICmpInst(Pred
, BOp0
, BOp1
);
3678 else if (BO
->hasOneUse()) {
3679 OverflowResult OR
= computeOverflow(
3680 Instruction::Mul
, BO
->getOpcode() == Instruction::SDiv
, BOp1
,
3681 Cmp
.getOperand(1), BO
);
3682 if (OR
== OverflowResult::NeverOverflows
) {
3684 Builder
.CreateMul(BOp1
, ConstantInt::get(BO
->getType(), C
));
3685 return new ICmpInst(Pred
, YC
, BOp0
);
3689 if (BO
->getOpcode() == Instruction::UDiv
&& C
.isZero()) {
3690 // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A)
3691 auto NewPred
= isICMP_NE
? ICmpInst::ICMP_ULE
: ICmpInst::ICMP_UGT
;
3692 return new ICmpInst(NewPred
, BOp1
, BOp0
);
3701 static Instruction
*foldCtpopPow2Test(ICmpInst
&I
, IntrinsicInst
*CtpopLhs
,
3703 InstCombiner::BuilderTy
&Builder
,
3704 const SimplifyQuery
&Q
) {
3705 assert(CtpopLhs
->getIntrinsicID() == Intrinsic::ctpop
&&
3706 "Non-ctpop intrin in ctpop fold");
3707 if (!CtpopLhs
->hasOneUse())
3711 // isPow2OrZero : ctpop(X) u< 2
3712 // isPow2 : ctpop(X) == 1
3713 // NotPow2OrZero: ctpop(X) u> 1
3714 // NotPow2 : ctpop(X) != 1
3715 // If we know any bit of X can be folded to:
3716 // IsPow2 : X & (~Bit) == 0
3717 // NotPow2 : X & (~Bit) != 0
3718 const ICmpInst::Predicate Pred
= I
.getPredicate();
3719 if (((I
.isEquality() || Pred
== ICmpInst::ICMP_UGT
) && CRhs
== 1) ||
3720 (Pred
== ICmpInst::ICMP_ULT
&& CRhs
== 2)) {
3721 Value
*Op
= CtpopLhs
->getArgOperand(0);
3722 KnownBits OpKnown
= computeKnownBits(Op
, Q
.DL
,
3723 /*Depth*/ 0, Q
.AC
, Q
.CxtI
, Q
.DT
);
3724 // No need to check for count > 1, that should be already constant folded.
3725 if (OpKnown
.countMinPopulation() == 1) {
3726 Value
*And
= Builder
.CreateAnd(
3727 Op
, Constant::getIntegerValue(Op
->getType(), ~(OpKnown
.One
)));
3728 return new ICmpInst(
3729 (Pred
== ICmpInst::ICMP_EQ
|| Pred
== ICmpInst::ICMP_ULT
)
3731 : ICmpInst::ICMP_NE
,
3732 And
, Constant::getNullValue(Op
->getType()));
3739 /// Fold an equality icmp with LLVM intrinsic and constant operand.
3740 Instruction
*InstCombinerImpl::foldICmpEqIntrinsicWithConstant(
3741 ICmpInst
&Cmp
, IntrinsicInst
*II
, const APInt
&C
) {
3742 Type
*Ty
= II
->getType();
3743 unsigned BitWidth
= C
.getBitWidth();
3744 const ICmpInst::Predicate Pred
= Cmp
.getPredicate();
3746 switch (II
->getIntrinsicID()) {
3747 case Intrinsic::abs
:
3748 // abs(A) == 0 -> A == 0
3749 // abs(A) == INT_MIN -> A == INT_MIN
3750 if (C
.isZero() || C
.isMinSignedValue())
3751 return new ICmpInst(Pred
, II
->getArgOperand(0), ConstantInt::get(Ty
, C
));
3754 case Intrinsic::bswap
:
3755 // bswap(A) == C -> A == bswap(C)
3756 return new ICmpInst(Pred
, II
->getArgOperand(0),
3757 ConstantInt::get(Ty
, C
.byteSwap()));
3759 case Intrinsic::bitreverse
:
3760 // bitreverse(A) == C -> A == bitreverse(C)
3761 return new ICmpInst(Pred
, II
->getArgOperand(0),
3762 ConstantInt::get(Ty
, C
.reverseBits()));
3764 case Intrinsic::ctlz
:
3765 case Intrinsic::cttz
: {
3766 // ctz(A) == bitwidth(A) -> A == 0 and likewise for !=
3768 return new ICmpInst(Pred
, II
->getArgOperand(0),
3769 ConstantInt::getNullValue(Ty
));
3771 // ctz(A) == C -> A & Mask1 == Mask2, where Mask2 only has bit C set
3772 // and Mask1 has bits 0..C+1 set. Similar for ctl, but for high bits.
3773 // Limit to one use to ensure we don't increase instruction count.
3774 unsigned Num
= C
.getLimitedValue(BitWidth
);
3775 if (Num
!= BitWidth
&& II
->hasOneUse()) {
3776 bool IsTrailing
= II
->getIntrinsicID() == Intrinsic::cttz
;
3777 APInt Mask1
= IsTrailing
? APInt::getLowBitsSet(BitWidth
, Num
+ 1)
3778 : APInt::getHighBitsSet(BitWidth
, Num
+ 1);
3779 APInt Mask2
= IsTrailing
3780 ? APInt::getOneBitSet(BitWidth
, Num
)
3781 : APInt::getOneBitSet(BitWidth
, BitWidth
- Num
- 1);
3782 return new ICmpInst(Pred
, Builder
.CreateAnd(II
->getArgOperand(0), Mask1
),
3783 ConstantInt::get(Ty
, Mask2
));
3788 case Intrinsic::ctpop
: {
3789 // popcount(A) == 0 -> A == 0 and likewise for !=
3790 // popcount(A) == bitwidth(A) -> A == -1 and likewise for !=
3791 bool IsZero
= C
.isZero();
3792 if (IsZero
|| C
== BitWidth
)
3793 return new ICmpInst(Pred
, II
->getArgOperand(0),
3794 IsZero
? Constant::getNullValue(Ty
)
3795 : Constant::getAllOnesValue(Ty
));
3800 case Intrinsic::fshl
:
3801 case Intrinsic::fshr
:
3802 if (II
->getArgOperand(0) == II
->getArgOperand(1)) {
3803 const APInt
*RotAmtC
;
3804 // ror(X, RotAmtC) == C --> X == rol(C, RotAmtC)
3805 // rol(X, RotAmtC) == C --> X == ror(C, RotAmtC)
3806 if (match(II
->getArgOperand(2), m_APInt(RotAmtC
)))
3807 return new ICmpInst(Pred
, II
->getArgOperand(0),
3808 II
->getIntrinsicID() == Intrinsic::fshl
3809 ? ConstantInt::get(Ty
, C
.rotr(*RotAmtC
))
3810 : ConstantInt::get(Ty
, C
.rotl(*RotAmtC
)));
3814 case Intrinsic::umax
:
3815 case Intrinsic::uadd_sat
: {
3816 // uadd.sat(a, b) == 0 -> (a | b) == 0
3817 // umax(a, b) == 0 -> (a | b) == 0
3818 if (C
.isZero() && II
->hasOneUse()) {
3819 Value
*Or
= Builder
.CreateOr(II
->getArgOperand(0), II
->getArgOperand(1));
3820 return new ICmpInst(Pred
, Or
, Constant::getNullValue(Ty
));
3825 case Intrinsic::ssub_sat
:
3826 // ssub.sat(a, b) == 0 -> a == b
3828 return new ICmpInst(Pred
, II
->getArgOperand(0), II
->getArgOperand(1));
3830 case Intrinsic::usub_sat
: {
3831 // usub.sat(a, b) == 0 -> a <= b
3833 ICmpInst::Predicate NewPred
=
3834 Pred
== ICmpInst::ICMP_EQ
? ICmpInst::ICMP_ULE
: ICmpInst::ICMP_UGT
;
3835 return new ICmpInst(NewPred
, II
->getArgOperand(0), II
->getArgOperand(1));
3846 /// Fold an icmp with LLVM intrinsics
3847 static Instruction
*
3848 foldICmpIntrinsicWithIntrinsic(ICmpInst
&Cmp
,
3849 InstCombiner::BuilderTy
&Builder
) {
3850 assert(Cmp
.isEquality());
3852 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
3853 Value
*Op0
= Cmp
.getOperand(0);
3854 Value
*Op1
= Cmp
.getOperand(1);
3855 const auto *IIOp0
= dyn_cast
<IntrinsicInst
>(Op0
);
3856 const auto *IIOp1
= dyn_cast
<IntrinsicInst
>(Op1
);
3857 if (!IIOp0
|| !IIOp1
|| IIOp0
->getIntrinsicID() != IIOp1
->getIntrinsicID())
3860 switch (IIOp0
->getIntrinsicID()) {
3861 case Intrinsic::bswap
:
3862 case Intrinsic::bitreverse
:
3863 // If both operands are byte-swapped or bit-reversed, just compare the
3865 return new ICmpInst(Pred
, IIOp0
->getOperand(0), IIOp1
->getOperand(0));
3866 case Intrinsic::fshl
:
3867 case Intrinsic::fshr
: {
3868 // If both operands are rotated by same amount, just compare the
3870 if (IIOp0
->getOperand(0) != IIOp0
->getOperand(1))
3872 if (IIOp1
->getOperand(0) != IIOp1
->getOperand(1))
3874 if (IIOp0
->getOperand(2) == IIOp1
->getOperand(2))
3875 return new ICmpInst(Pred
, IIOp0
->getOperand(0), IIOp1
->getOperand(0));
3877 // rotate(X, AmtX) == rotate(Y, AmtY)
3878 // -> rotate(X, AmtX - AmtY) == Y
3879 // Do this if either both rotates have one use or if only one has one use
3880 // and AmtX/AmtY are constants.
3881 unsigned OneUses
= IIOp0
->hasOneUse() + IIOp1
->hasOneUse();
3883 (OneUses
== 1 && match(IIOp0
->getOperand(2), m_ImmConstant()) &&
3884 match(IIOp1
->getOperand(2), m_ImmConstant()))) {
3886 Builder
.CreateSub(IIOp0
->getOperand(2), IIOp1
->getOperand(2));
3887 Value
*CombinedRotate
= Builder
.CreateIntrinsic(
3888 Op0
->getType(), IIOp0
->getIntrinsicID(),
3889 {IIOp0
->getOperand(0), IIOp0
->getOperand(0), SubAmt
});
3890 return new ICmpInst(Pred
, IIOp1
->getOperand(0), CombinedRotate
);
3900 /// Try to fold integer comparisons with a constant operand: icmp Pred X, C
3901 /// where X is some kind of instruction and C is AllowPoison.
3902 /// TODO: Move more folds which allow poison to this function.
3904 InstCombinerImpl::foldICmpInstWithConstantAllowPoison(ICmpInst
&Cmp
,
3906 const ICmpInst::Predicate Pred
= Cmp
.getPredicate();
3907 if (auto *II
= dyn_cast
<IntrinsicInst
>(Cmp
.getOperand(0))) {
3908 switch (II
->getIntrinsicID()) {
3911 case Intrinsic::fshl
:
3912 case Intrinsic::fshr
:
3913 if (Cmp
.isEquality() && II
->getArgOperand(0) == II
->getArgOperand(1)) {
3914 // (rot X, ?) == 0/-1 --> X == 0/-1
3915 if (C
.isZero() || C
.isAllOnes())
3916 return new ICmpInst(Pred
, II
->getArgOperand(0), Cmp
.getOperand(1));
3925 /// Fold an icmp with BinaryOp and constant operand: icmp Pred BO, C.
3926 Instruction
*InstCombinerImpl::foldICmpBinOpWithConstant(ICmpInst
&Cmp
,
3929 switch (BO
->getOpcode()) {
3930 case Instruction::Xor
:
3931 if (Instruction
*I
= foldICmpXorConstant(Cmp
, BO
, C
))
3934 case Instruction::And
:
3935 if (Instruction
*I
= foldICmpAndConstant(Cmp
, BO
, C
))
3938 case Instruction::Or
:
3939 if (Instruction
*I
= foldICmpOrConstant(Cmp
, BO
, C
))
3942 case Instruction::Mul
:
3943 if (Instruction
*I
= foldICmpMulConstant(Cmp
, BO
, C
))
3946 case Instruction::Shl
:
3947 if (Instruction
*I
= foldICmpShlConstant(Cmp
, BO
, C
))
3950 case Instruction::LShr
:
3951 case Instruction::AShr
:
3952 if (Instruction
*I
= foldICmpShrConstant(Cmp
, BO
, C
))
3955 case Instruction::SRem
:
3956 if (Instruction
*I
= foldICmpSRemConstant(Cmp
, BO
, C
))
3959 case Instruction::UDiv
:
3960 if (Instruction
*I
= foldICmpUDivConstant(Cmp
, BO
, C
))
3963 case Instruction::SDiv
:
3964 if (Instruction
*I
= foldICmpDivConstant(Cmp
, BO
, C
))
3967 case Instruction::Sub
:
3968 if (Instruction
*I
= foldICmpSubConstant(Cmp
, BO
, C
))
3971 case Instruction::Add
:
3972 if (Instruction
*I
= foldICmpAddConstant(Cmp
, BO
, C
))
3979 // TODO: These folds could be refactored to be part of the above calls.
3980 return foldICmpBinOpEqualityWithConstant(Cmp
, BO
, C
);
3983 static Instruction
*
3984 foldICmpUSubSatOrUAddSatWithConstant(CmpPredicate Pred
, SaturatingInst
*II
,
3986 InstCombiner::BuilderTy
&Builder
) {
3987 // This transform may end up producing more than one instruction for the
3988 // intrinsic, so limit it to one user of the intrinsic.
3989 if (!II
->hasOneUse())
3992 // Let Y = [add/sub]_sat(X, C) pred C2
3993 // SatVal = The saturating value for the operation
3994 // WillWrap = Whether or not the operation will underflow / overflow
3995 // => Y = (WillWrap ? SatVal : (X binop C)) pred C2
3996 // => Y = WillWrap ? (SatVal pred C2) : ((X binop C) pred C2)
3998 // When (SatVal pred C2) is true, then
3999 // Y = WillWrap ? true : ((X binop C) pred C2)
4000 // => Y = WillWrap || ((X binop C) pred C2)
4002 // Y = WillWrap ? false : ((X binop C) pred C2)
4003 // => Y = !WillWrap ? ((X binop C) pred C2) : false
4004 // => Y = !WillWrap && ((X binop C) pred C2)
4005 Value
*Op0
= II
->getOperand(0);
4006 Value
*Op1
= II
->getOperand(1);
4009 // This transform only works when the intrinsic has an integral constant or
4010 // splat vector as the second operand.
4011 if (!match(Op1
, m_APInt(COp1
)))
4015 switch (II
->getIntrinsicID()) {
4018 "This function only works with usub_sat and uadd_sat for now!");
4019 case Intrinsic::uadd_sat
:
4020 SatVal
= APInt::getAllOnes(C
.getBitWidth());
4022 case Intrinsic::usub_sat
:
4023 SatVal
= APInt::getZero(C
.getBitWidth());
4027 // Check (SatVal pred C2)
4028 bool SatValCheck
= ICmpInst::compare(SatVal
, C
, Pred
);
4031 ConstantRange C1
= ConstantRange::makeExactNoWrapRegion(
4032 II
->getBinaryOp(), *COp1
, II
->getNoWrapKind());
4038 ConstantRange C2
= ConstantRange::makeExactICmpRegion(Pred
, C
);
4039 if (II
->getBinaryOp() == Instruction::Add
)
4044 Instruction::BinaryOps CombiningOp
=
4045 SatValCheck
? Instruction::BinaryOps::Or
: Instruction::BinaryOps::And
;
4047 std::optional
<ConstantRange
> Combination
;
4048 if (CombiningOp
== Instruction::BinaryOps::Or
)
4049 Combination
= C1
.exactUnionWith(C2
);
4050 else /* CombiningOp == Instruction::BinaryOps::And */
4051 Combination
= C1
.exactIntersectWith(C2
);
4056 CmpInst::Predicate EquivPred
;
4060 Combination
->getEquivalentICmp(EquivPred
, EquivInt
, EquivOffset
);
4062 return new ICmpInst(
4064 Builder
.CreateAdd(Op0
, ConstantInt::get(Op1
->getType(), EquivOffset
)),
4065 ConstantInt::get(Op1
->getType(), EquivInt
));
4068 static Instruction
*
4069 foldICmpOfCmpIntrinsicWithConstant(CmpPredicate Pred
, IntrinsicInst
*I
,
4071 InstCombiner::BuilderTy
&Builder
) {
4072 std::optional
<ICmpInst::Predicate
> NewPredicate
= std::nullopt
;
4074 case ICmpInst::ICMP_EQ
:
4075 case ICmpInst::ICMP_NE
:
4077 NewPredicate
= Pred
;
4080 Pred
== ICmpInst::ICMP_EQ
? ICmpInst::ICMP_UGT
: ICmpInst::ICMP_ULE
;
4081 else if (C
.isAllOnes())
4083 Pred
== ICmpInst::ICMP_EQ
? ICmpInst::ICMP_ULT
: ICmpInst::ICMP_UGE
;
4086 case ICmpInst::ICMP_SGT
:
4088 NewPredicate
= ICmpInst::ICMP_UGE
;
4089 else if (C
.isZero())
4090 NewPredicate
= ICmpInst::ICMP_UGT
;
4093 case ICmpInst::ICMP_SLT
:
4095 NewPredicate
= ICmpInst::ICMP_ULT
;
4097 NewPredicate
= ICmpInst::ICMP_ULE
;
4100 case ICmpInst::ICMP_ULT
:
4102 NewPredicate
= ICmpInst::ICMP_UGE
;
4105 case ICmpInst::ICMP_UGT
:
4106 if (!C
.isZero() && !C
.isAllOnes())
4107 NewPredicate
= ICmpInst::ICMP_ULT
;
4117 if (I
->getIntrinsicID() == Intrinsic::scmp
)
4118 NewPredicate
= ICmpInst::getSignedPredicate(*NewPredicate
);
4119 Value
*LHS
= I
->getOperand(0);
4120 Value
*RHS
= I
->getOperand(1);
4121 return new ICmpInst(*NewPredicate
, LHS
, RHS
);
4124 /// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C.
4125 Instruction
*InstCombinerImpl::foldICmpIntrinsicWithConstant(ICmpInst
&Cmp
,
4128 ICmpInst::Predicate Pred
= Cmp
.getPredicate();
4130 // Handle folds that apply for any kind of icmp.
4131 switch (II
->getIntrinsicID()) {
4134 case Intrinsic::uadd_sat
:
4135 case Intrinsic::usub_sat
:
4136 if (auto *Folded
= foldICmpUSubSatOrUAddSatWithConstant(
4137 Pred
, cast
<SaturatingInst
>(II
), C
, Builder
))
4140 case Intrinsic::ctpop
: {
4141 const SimplifyQuery Q
= SQ
.getWithInstruction(&Cmp
);
4142 if (Instruction
*R
= foldCtpopPow2Test(Cmp
, II
, C
, Builder
, Q
))
4145 case Intrinsic::scmp
:
4146 case Intrinsic::ucmp
:
4147 if (auto *Folded
= foldICmpOfCmpIntrinsicWithConstant(Pred
, II
, C
, Builder
))
4152 if (Cmp
.isEquality())
4153 return foldICmpEqIntrinsicWithConstant(Cmp
, II
, C
);
4155 Type
*Ty
= II
->getType();
4156 unsigned BitWidth
= C
.getBitWidth();
4157 switch (II
->getIntrinsicID()) {
4158 case Intrinsic::ctpop
: {
4159 // (ctpop X > BitWidth - 1) --> X == -1
4160 Value
*X
= II
->getArgOperand(0);
4161 if (C
== BitWidth
- 1 && Pred
== ICmpInst::ICMP_UGT
)
4162 return CmpInst::Create(Instruction::ICmp
, ICmpInst::ICMP_EQ
, X
,
4163 ConstantInt::getAllOnesValue(Ty
));
4164 // (ctpop X < BitWidth) --> X != -1
4165 if (C
== BitWidth
&& Pred
== ICmpInst::ICMP_ULT
)
4166 return CmpInst::Create(Instruction::ICmp
, ICmpInst::ICMP_NE
, X
,
4167 ConstantInt::getAllOnesValue(Ty
));
4170 case Intrinsic::ctlz
: {
4171 // ctlz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX < 0b00010000
4172 if (Pred
== ICmpInst::ICMP_UGT
&& C
.ult(BitWidth
)) {
4173 unsigned Num
= C
.getLimitedValue();
4174 APInt Limit
= APInt::getOneBitSet(BitWidth
, BitWidth
- Num
- 1);
4175 return CmpInst::Create(Instruction::ICmp
, ICmpInst::ICMP_ULT
,
4176 II
->getArgOperand(0), ConstantInt::get(Ty
, Limit
));
4179 // ctlz(0bXXXXXXXX) < 3 -> 0bXXXXXXXX > 0b00011111
4180 if (Pred
== ICmpInst::ICMP_ULT
&& C
.uge(1) && C
.ule(BitWidth
)) {
4181 unsigned Num
= C
.getLimitedValue();
4182 APInt Limit
= APInt::getLowBitsSet(BitWidth
, BitWidth
- Num
);
4183 return CmpInst::Create(Instruction::ICmp
, ICmpInst::ICMP_UGT
,
4184 II
->getArgOperand(0), ConstantInt::get(Ty
, Limit
));
4188 case Intrinsic::cttz
: {
4189 // Limit to one use to ensure we don't increase instruction count.
4190 if (!II
->hasOneUse())
4193 // cttz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX & 0b00001111 == 0
4194 if (Pred
== ICmpInst::ICMP_UGT
&& C
.ult(BitWidth
)) {
4195 APInt Mask
= APInt::getLowBitsSet(BitWidth
, C
.getLimitedValue() + 1);
4196 return CmpInst::Create(Instruction::ICmp
, ICmpInst::ICMP_EQ
,
4197 Builder
.CreateAnd(II
->getArgOperand(0), Mask
),
4198 ConstantInt::getNullValue(Ty
));
4201 // cttz(0bXXXXXXXX) < 3 -> 0bXXXXXXXX & 0b00000111 != 0
4202 if (Pred
== ICmpInst::ICMP_ULT
&& C
.uge(1) && C
.ule(BitWidth
)) {
4203 APInt Mask
= APInt::getLowBitsSet(BitWidth
, C
.getLimitedValue());
4204 return CmpInst::Create(Instruction::ICmp
, ICmpInst::ICMP_NE
,
4205 Builder
.CreateAnd(II
->getArgOperand(0), Mask
),
4206 ConstantInt::getNullValue(Ty
));
4210 case Intrinsic::ssub_sat
:
4211 // ssub.sat(a, b) spred 0 -> a spred b
4212 if (ICmpInst::isSigned(Pred
)) {
4214 return new ICmpInst(Pred
, II
->getArgOperand(0), II
->getArgOperand(1));
4215 // X s<= 0 is cannonicalized to X s< 1
4216 if (Pred
== ICmpInst::ICMP_SLT
&& C
.isOne())
4217 return new ICmpInst(ICmpInst::ICMP_SLE
, II
->getArgOperand(0),
4218 II
->getArgOperand(1));
4219 // X s>= 0 is cannonicalized to X s> -1
4220 if (Pred
== ICmpInst::ICMP_SGT
&& C
.isAllOnes())
4221 return new ICmpInst(ICmpInst::ICMP_SGE
, II
->getArgOperand(0),
4222 II
->getArgOperand(1));
4232 /// Handle icmp with constant (but not simple integer constant) RHS.
4233 Instruction
*InstCombinerImpl::foldICmpInstWithConstantNotInt(ICmpInst
&I
) {
4234 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
4235 Constant
*RHSC
= dyn_cast
<Constant
>(Op1
);
4236 Instruction
*LHSI
= dyn_cast
<Instruction
>(Op0
);
4240 switch (LHSI
->getOpcode()) {
4241 case Instruction::PHI
:
4242 if (Instruction
*NV
= foldOpIntoPhi(I
, cast
<PHINode
>(LHSI
)))
4245 case Instruction::IntToPtr
:
4246 // icmp pred inttoptr(X), null -> icmp pred X, 0
4247 if (RHSC
->isNullValue() &&
4248 DL
.getIntPtrType(RHSC
->getType()) == LHSI
->getOperand(0)->getType())
4249 return new ICmpInst(
4250 I
.getPredicate(), LHSI
->getOperand(0),
4251 Constant::getNullValue(LHSI
->getOperand(0)->getType()));
4254 case Instruction::Load
:
4255 // Try to optimize things like "A[i] > 4" to index computations.
4256 if (GetElementPtrInst
*GEP
=
4257 dyn_cast
<GetElementPtrInst
>(LHSI
->getOperand(0)))
4258 if (GlobalVariable
*GV
= dyn_cast
<GlobalVariable
>(GEP
->getOperand(0)))
4259 if (Instruction
*Res
=
4260 foldCmpLoadFromIndexedGlobal(cast
<LoadInst
>(LHSI
), GEP
, GV
, I
))
4268 Instruction
*InstCombinerImpl::foldSelectICmp(CmpPredicate Pred
, SelectInst
*SI
,
4269 Value
*RHS
, const ICmpInst
&I
) {
4270 // Try to fold the comparison into the select arms, which will cause the
4271 // select to be converted into a logical and/or.
4272 auto SimplifyOp
= [&](Value
*Op
, bool SelectCondIsTrue
) -> Value
* {
4273 if (Value
*Res
= simplifyICmpInst(Pred
, Op
, RHS
, SQ
))
4275 if (std::optional
<bool> Impl
= isImpliedCondition(
4276 SI
->getCondition(), Pred
, Op
, RHS
, DL
, SelectCondIsTrue
))
4277 return ConstantInt::get(I
.getType(), *Impl
);
4281 ConstantInt
*CI
= nullptr;
4282 Value
*Op1
= SimplifyOp(SI
->getOperand(1), true);
4284 CI
= dyn_cast
<ConstantInt
>(Op1
);
4286 Value
*Op2
= SimplifyOp(SI
->getOperand(2), false);
4288 CI
= dyn_cast
<ConstantInt
>(Op2
);
4290 auto Simplifies
= [&](Value
*Op
, unsigned Idx
) {
4291 // A comparison of ucmp/scmp with a constant will fold into an icmp.
4294 (isa
<CmpIntrinsic
>(SI
->getOperand(Idx
)) &&
4295 SI
->getOperand(Idx
)->hasOneUse() && match(RHS
, m_APInt(Dummy
)));
4298 // We only want to perform this transformation if it will not lead to
4299 // additional code. This is true if either both sides of the select
4300 // fold to a constant (in which case the icmp is replaced with a select
4301 // which will usually simplify) or this is the only user of the
4302 // select (in which case we are trading a select+icmp for a simpler
4303 // select+icmp) or all uses of the select can be replaced based on
4304 // dominance information ("Global cases").
4305 bool Transform
= false;
4308 else if (Simplifies(Op1
, 1) || Simplifies(Op2
, 2)) {
4310 if (SI
->hasOneUse())
4313 else if (CI
&& !CI
->isZero())
4314 // When Op1 is constant try replacing select with second operand.
4315 // Otherwise Op2 is constant and try replacing select with first
4317 Transform
= replacedSelectWithOperand(SI
, &I
, Op1
? 2 : 1);
4321 Op1
= Builder
.CreateICmp(Pred
, SI
->getOperand(1), RHS
, I
.getName());
4323 Op2
= Builder
.CreateICmp(Pred
, SI
->getOperand(2), RHS
, I
.getName());
4324 return SelectInst::Create(SI
->getOperand(0), Op1
, Op2
);
4330 // Returns whether V is a Mask ((X + 1) & X == 0) or ~Mask (-Pow2OrZero)
4331 static bool isMaskOrZero(const Value
*V
, bool Not
, const SimplifyQuery
&Q
,
4332 unsigned Depth
= 0) {
4333 if (Not
? match(V
, m_NegatedPower2OrZero()) : match(V
, m_LowBitMaskOrZero()))
4335 if (V
->getType()->getScalarSizeInBits() == 1)
4337 if (Depth
++ >= MaxAnalysisRecursionDepth
)
4340 const Instruction
*I
= dyn_cast
<Instruction
>(V
);
4343 switch (I
->getOpcode()) {
4344 case Instruction::ZExt
:
4345 // ZExt(Mask) is a Mask.
4346 return !Not
&& isMaskOrZero(I
->getOperand(0), Not
, Q
, Depth
);
4347 case Instruction::SExt
:
4348 // SExt(Mask) is a Mask.
4349 // SExt(~Mask) is a ~Mask.
4350 return isMaskOrZero(I
->getOperand(0), Not
, Q
, Depth
);
4351 case Instruction::And
:
4352 case Instruction::Or
:
4353 // Mask0 | Mask1 is a Mask.
4354 // Mask0 & Mask1 is a Mask.
4355 // ~Mask0 | ~Mask1 is a ~Mask.
4356 // ~Mask0 & ~Mask1 is a ~Mask.
4357 return isMaskOrZero(I
->getOperand(1), Not
, Q
, Depth
) &&
4358 isMaskOrZero(I
->getOperand(0), Not
, Q
, Depth
);
4359 case Instruction::Xor
:
4360 if (match(V
, m_Not(m_Value(X
))))
4361 return isMaskOrZero(X
, !Not
, Q
, Depth
);
4363 // (X ^ -X) is a ~Mask
4365 return match(V
, m_c_Xor(m_Value(X
), m_Neg(m_Deferred(X
))));
4366 // (X ^ (X - 1)) is a Mask
4368 return match(V
, m_c_Xor(m_Value(X
), m_Add(m_Deferred(X
), m_AllOnes())));
4369 case Instruction::Select
:
4370 // c ? Mask0 : Mask1 is a Mask.
4371 return isMaskOrZero(I
->getOperand(1), Not
, Q
, Depth
) &&
4372 isMaskOrZero(I
->getOperand(2), Not
, Q
, Depth
);
4373 case Instruction::Shl
:
4374 // (~Mask) << X is a ~Mask.
4375 return Not
&& isMaskOrZero(I
->getOperand(0), Not
, Q
, Depth
);
4376 case Instruction::LShr
:
4377 // Mask >> X is a Mask.
4378 return !Not
&& isMaskOrZero(I
->getOperand(0), Not
, Q
, Depth
);
4379 case Instruction::AShr
:
4380 // Mask s>> X is a Mask.
4381 // ~Mask s>> X is a ~Mask.
4382 return isMaskOrZero(I
->getOperand(0), Not
, Q
, Depth
);
4383 case Instruction::Add
:
4384 // Pow2 - 1 is a Mask.
4385 if (!Not
&& match(I
->getOperand(1), m_AllOnes()))
4386 return isKnownToBeAPowerOfTwo(I
->getOperand(0), Q
.DL
, /*OrZero*/ true,
4387 Depth
, Q
.AC
, Q
.CxtI
, Q
.DT
);
4389 case Instruction::Sub
:
4390 // -Pow2 is a ~Mask.
4391 if (Not
&& match(I
->getOperand(0), m_Zero()))
4392 return isKnownToBeAPowerOfTwo(I
->getOperand(1), Q
.DL
, /*OrZero*/ true,
4393 Depth
, Q
.AC
, Q
.CxtI
, Q
.DT
);
4395 case Instruction::Call
: {
4396 if (auto *II
= dyn_cast
<IntrinsicInst
>(I
)) {
4397 switch (II
->getIntrinsicID()) {
4398 // min/max(Mask0, Mask1) is a Mask.
4399 // min/max(~Mask0, ~Mask1) is a ~Mask.
4400 case Intrinsic::umax
:
4401 case Intrinsic::smax
:
4402 case Intrinsic::umin
:
4403 case Intrinsic::smin
:
4404 return isMaskOrZero(II
->getArgOperand(1), Not
, Q
, Depth
) &&
4405 isMaskOrZero(II
->getArgOperand(0), Not
, Q
, Depth
);
4407 // In the context of masks, bitreverse(Mask) == ~Mask
4408 case Intrinsic::bitreverse
:
4409 return isMaskOrZero(II
->getArgOperand(0), !Not
, Q
, Depth
);
4422 /// Some comparisons can be simplified.
4423 /// In this case, we are looking for comparisons that look like
4424 /// a check for a lossy truncation.
4426 /// icmp SrcPred (x & Mask), x to icmp DstPred x, Mask
4427 /// icmp SrcPred (x & ~Mask), ~Mask to icmp DstPred x, ~Mask
4428 /// icmp eq/ne (x & ~Mask), 0 to icmp DstPred x, Mask
4429 /// icmp eq/ne (~x | Mask), -1 to icmp DstPred x, Mask
4430 /// Where Mask is some pattern that produces all-ones in low bits:
4432 /// ((-1 << y) >> y) <- non-canonical, has extra uses
4434 /// ((1 << y) + (-1)) <- non-canonical, has extra uses
4435 /// The Mask can be a constant, too.
4436 /// For some predicates, the operands are commutative.
4437 /// For others, x can only be on a specific side.
4438 static Value
*foldICmpWithLowBitMaskedVal(CmpPredicate Pred
, Value
*Op0
,
4439 Value
*Op1
, const SimplifyQuery
&Q
,
4442 ICmpInst::Predicate DstPred
;
4444 case ICmpInst::Predicate::ICMP_EQ
:
4449 // x & ~Mask == ~Mask
4451 DstPred
= ICmpInst::Predicate::ICMP_ULE
;
4453 case ICmpInst::Predicate::ICMP_NE
:
4458 // x & ~Mask != ~Mask
4460 DstPred
= ICmpInst::Predicate::ICMP_UGT
;
4462 case ICmpInst::Predicate::ICMP_ULT
:
4465 // x & ~Mask u< ~Mask
4467 DstPred
= ICmpInst::Predicate::ICMP_UGT
;
4469 case ICmpInst::Predicate::ICMP_UGE
:
4472 // x & ~Mask u>= ~Mask
4474 DstPred
= ICmpInst::Predicate::ICMP_ULE
;
4476 case ICmpInst::Predicate::ICMP_SLT
:
4477 // x & Mask s< x [iff Mask s>= 0]
4479 // x & ~Mask s< ~Mask [iff ~Mask != 0]
4481 DstPred
= ICmpInst::Predicate::ICMP_SGT
;
4483 case ICmpInst::Predicate::ICMP_SGE
:
4484 // x & Mask s>= x [iff Mask s>= 0]
4486 // x & ~Mask s>= ~Mask [iff ~Mask != 0]
4488 DstPred
= ICmpInst::Predicate::ICMP_SLE
;
4491 // We don't support sgt,sle
4492 // ult/ugt are simplified to true/false respectively.
4497 // Put search code in lambda for early positive returns.
4498 auto IsLowBitMask
= [&]() {
4499 if (match(Op0
, m_c_And(m_Specific(Op1
), m_Value(M
)))) {
4501 // Look for: x & Mask pred x
4502 if (isMaskOrZero(M
, /*Not=*/false, Q
)) {
4503 return !ICmpInst::isSigned(Pred
) ||
4504 (match(M
, m_NonNegative()) || isKnownNonNegative(M
, Q
));
4507 // Look for: x & ~Mask pred ~Mask
4508 if (isMaskOrZero(X
, /*Not=*/true, Q
)) {
4509 return !ICmpInst::isSigned(Pred
) || isKnownNonZero(X
, Q
);
4513 if (ICmpInst::isEquality(Pred
) && match(Op1
, m_AllOnes()) &&
4514 match(Op0
, m_OneUse(m_Or(m_Value(X
), m_Value(M
))))) {
4516 auto Check
= [&]() {
4517 // Look for: ~x | Mask == -1
4518 if (isMaskOrZero(M
, /*Not=*/false, Q
)) {
4520 IC
.getFreelyInverted(X
, X
->hasOneUse(), &IC
.Builder
)) {
4532 if (ICmpInst::isEquality(Pred
) && match(Op1
, m_Zero()) &&
4533 match(Op0
, m_OneUse(m_And(m_Value(X
), m_Value(M
))))) {
4534 auto Check
= [&]() {
4535 // Look for: x & ~Mask == 0
4536 if (isMaskOrZero(M
, /*Not=*/true, Q
)) {
4538 IC
.getFreelyInverted(M
, M
->hasOneUse(), &IC
.Builder
)) {
4553 if (!IsLowBitMask())
4556 return IC
.Builder
.CreateICmp(DstPred
, X
, M
);
4559 /// Some comparisons can be simplified.
4560 /// In this case, we are looking for comparisons that look like
4561 /// a check for a lossy signed truncation.
4562 /// Folds: (MaskedBits is a constant.)
4563 /// ((%x << MaskedBits) a>> MaskedBits) SrcPred %x
4565 /// (add %x, (1 << (KeptBits-1))) DstPred (1 << KeptBits)
4566 /// Where KeptBits = bitwidth(%x) - MaskedBits
4568 foldICmpWithTruncSignExtendedVal(ICmpInst
&I
,
4569 InstCombiner::BuilderTy
&Builder
) {
4570 CmpPredicate SrcPred
;
4572 const APInt
*C0
, *C1
; // FIXME: non-splats, potentially with undef.
4573 // We are ok with 'shl' having multiple uses, but 'ashr' must be one-use.
4574 if (!match(&I
, m_c_ICmp(SrcPred
,
4575 m_OneUse(m_AShr(m_Shl(m_Value(X
), m_APInt(C0
)),
4580 // Potential handling of non-splats: for each element:
4581 // * if both are undef, replace with constant 0.
4582 // Because (1<<0) is OK and is 1, and ((1<<0)>>1) is also OK and is 0.
4583 // * if both are not undef, and are different, bailout.
4584 // * else, only one is undef, then pick the non-undef one.
4586 // The shift amount must be equal.
4589 const APInt
&MaskedBits
= *C0
;
4590 assert(MaskedBits
!= 0 && "shift by zero should be folded away already.");
4592 ICmpInst::Predicate DstPred
;
4594 case ICmpInst::Predicate::ICMP_EQ
:
4595 // ((%x << MaskedBits) a>> MaskedBits) == %x
4597 // (add %x, (1 << (KeptBits-1))) u< (1 << KeptBits)
4598 DstPred
= ICmpInst::Predicate::ICMP_ULT
;
4600 case ICmpInst::Predicate::ICMP_NE
:
4601 // ((%x << MaskedBits) a>> MaskedBits) != %x
4603 // (add %x, (1 << (KeptBits-1))) u>= (1 << KeptBits)
4604 DstPred
= ICmpInst::Predicate::ICMP_UGE
;
4606 // FIXME: are more folds possible?
4611 auto *XType
= X
->getType();
4612 const unsigned XBitWidth
= XType
->getScalarSizeInBits();
4613 const APInt BitWidth
= APInt(XBitWidth
, XBitWidth
);
4614 assert(BitWidth
.ugt(MaskedBits
) && "shifts should leave some bits untouched");
4616 // KeptBits = bitwidth(%x) - MaskedBits
4617 const APInt KeptBits
= BitWidth
- MaskedBits
;
4618 assert(KeptBits
.ugt(0) && KeptBits
.ult(BitWidth
) && "unreachable");
4619 // ICmpCst = (1 << KeptBits)
4620 const APInt ICmpCst
= APInt(XBitWidth
, 1).shl(KeptBits
);
4621 assert(ICmpCst
.isPowerOf2());
4622 // AddCst = (1 << (KeptBits-1))
4623 const APInt AddCst
= ICmpCst
.lshr(1);
4624 assert(AddCst
.ult(ICmpCst
) && AddCst
.isPowerOf2());
4626 // T0 = add %x, AddCst
4627 Value
*T0
= Builder
.CreateAdd(X
, ConstantInt::get(XType
, AddCst
));
4628 // T1 = T0 DstPred ICmpCst
4629 Value
*T1
= Builder
.CreateICmp(DstPred
, T0
, ConstantInt::get(XType
, ICmpCst
));
4635 // icmp eq/ne (and ((x shift Q), (y oppositeshift K))), 0
4636 // we should move shifts to the same hand of 'and', i.e. rewrite as
4637 // icmp eq/ne (and (x shift (Q+K)), y), 0 iff (Q+K) u< bitwidth(x)
4638 // We are only interested in opposite logical shifts here.
4639 // One of the shifts can be truncated.
4640 // If we can, we want to end up creating 'lshr' shift.
4642 foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst
&I
, const SimplifyQuery SQ
,
4643 InstCombiner::BuilderTy
&Builder
) {
4644 if (!I
.isEquality() || !match(I
.getOperand(1), m_Zero()) ||
4645 !I
.getOperand(0)->hasOneUse())
4648 auto m_AnyLogicalShift
= m_LogicalShift(m_Value(), m_Value());
4650 // Look for an 'and' of two logical shifts, one of which may be truncated.
4651 // We use m_TruncOrSelf() on the RHS to correctly handle commutative case.
4652 Instruction
*XShift
, *MaybeTruncation
, *YShift
;
4655 m_c_And(m_CombineAnd(m_AnyLogicalShift
, m_Instruction(XShift
)),
4656 m_CombineAnd(m_TruncOrSelf(m_CombineAnd(
4657 m_AnyLogicalShift
, m_Instruction(YShift
))),
4658 m_Instruction(MaybeTruncation
)))))
4661 // We potentially looked past 'trunc', but only when matching YShift,
4662 // therefore YShift must have the widest type.
4663 Instruction
*WidestShift
= YShift
;
4664 // Therefore XShift must have the shallowest type.
4665 // Or they both have identical types if there was no truncation.
4666 Instruction
*NarrowestShift
= XShift
;
4668 Type
*WidestTy
= WidestShift
->getType();
4669 Type
*NarrowestTy
= NarrowestShift
->getType();
4670 assert(NarrowestTy
== I
.getOperand(0)->getType() &&
4671 "We did not look past any shifts while matching XShift though.");
4672 bool HadTrunc
= WidestTy
!= I
.getOperand(0)->getType();
4674 // If YShift is a 'lshr', swap the shifts around.
4675 if (match(YShift
, m_LShr(m_Value(), m_Value())))
4676 std::swap(XShift
, YShift
);
4678 // The shifts must be in opposite directions.
4679 auto XShiftOpcode
= XShift
->getOpcode();
4680 if (XShiftOpcode
== YShift
->getOpcode())
4681 return nullptr; // Do not care about same-direction shifts here.
4683 Value
*X
, *XShAmt
, *Y
, *YShAmt
;
4684 match(XShift
, m_BinOp(m_Value(X
), m_ZExtOrSelf(m_Value(XShAmt
))));
4685 match(YShift
, m_BinOp(m_Value(Y
), m_ZExtOrSelf(m_Value(YShAmt
))));
4687 // If one of the values being shifted is a constant, then we will end with
4688 // and+icmp, and [zext+]shift instrs will be constant-folded. If they are not,
4689 // however, we will need to ensure that we won't increase instruction count.
4690 if (!isa
<Constant
>(X
) && !isa
<Constant
>(Y
)) {
4691 // At least one of the hands of the 'and' should be one-use shift.
4692 if (!match(I
.getOperand(0),
4693 m_c_And(m_OneUse(m_AnyLogicalShift
), m_Value())))
4696 // Due to the 'trunc', we will need to widen X. For that either the old
4697 // 'trunc' or the shift amt in the non-truncated shift should be one-use.
4698 if (!MaybeTruncation
->hasOneUse() &&
4699 !NarrowestShift
->getOperand(1)->hasOneUse())
4704 // We have two shift amounts from two different shifts. The types of those
4705 // shift amounts may not match. If that's the case let's bailout now.
4706 if (XShAmt
->getType() != YShAmt
->getType())
4709 // As input, we have the following pattern:
4710 // icmp eq/ne (and ((x shift Q), (y oppositeshift K))), 0
4711 // We want to rewrite that as:
4712 // icmp eq/ne (and (x shift (Q+K)), y), 0 iff (Q+K) u< bitwidth(x)
4713 // While we know that originally (Q+K) would not overflow
4714 // (because 2 * (N-1) u<= iN -1), we have looked past extensions of
4715 // shift amounts. so it may now overflow in smaller bitwidth.
4716 // To ensure that does not happen, we need to ensure that the total maximal
4717 // shift amount is still representable in that smaller bit width.
4718 unsigned MaximalPossibleTotalShiftAmount
=
4719 (WidestTy
->getScalarSizeInBits() - 1) +
4720 (NarrowestTy
->getScalarSizeInBits() - 1);
4721 APInt MaximalRepresentableShiftAmount
=
4722 APInt::getAllOnes(XShAmt
->getType()->getScalarSizeInBits());
4723 if (MaximalRepresentableShiftAmount
.ult(MaximalPossibleTotalShiftAmount
))
4726 // Can we fold (XShAmt+YShAmt) ?
4727 auto *NewShAmt
= dyn_cast_or_null
<Constant
>(
4728 simplifyAddInst(XShAmt
, YShAmt
, /*isNSW=*/false,
4729 /*isNUW=*/false, SQ
.getWithInstruction(&I
)));
4732 if (NewShAmt
->getType() != WidestTy
) {
4734 ConstantFoldCastOperand(Instruction::ZExt
, NewShAmt
, WidestTy
, SQ
.DL
);
4738 unsigned WidestBitWidth
= WidestTy
->getScalarSizeInBits();
4740 // Is the new shift amount smaller than the bit width?
4741 // FIXME: could also rely on ConstantRange.
4742 if (!match(NewShAmt
,
4743 m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_ULT
,
4744 APInt(WidestBitWidth
, WidestBitWidth
))))
4747 // An extra legality check is needed if we had trunc-of-lshr.
4748 if (HadTrunc
&& match(WidestShift
, m_LShr(m_Value(), m_Value()))) {
4749 auto CanFold
= [NewShAmt
, WidestBitWidth
, NarrowestShift
, SQ
,
4751 // It isn't obvious whether it's worth it to analyze non-constants here.
4752 // Also, let's basically give up on non-splat cases, pessimizing vectors.
4753 // If *any* of these preconditions matches we can perform the fold.
4754 Constant
*NewShAmtSplat
= NewShAmt
->getType()->isVectorTy()
4755 ? NewShAmt
->getSplatValue()
4757 // If it's edge-case shift (by 0 or by WidestBitWidth-1) we can fold.
4758 if (NewShAmtSplat
&&
4759 (NewShAmtSplat
->isNullValue() ||
4760 NewShAmtSplat
->getUniqueInteger() == WidestBitWidth
- 1))
4762 // We consider *min* leading zeros so a single outlier
4763 // blocks the transform as opposed to allowing it.
4764 if (auto *C
= dyn_cast
<Constant
>(NarrowestShift
->getOperand(0))) {
4765 KnownBits Known
= computeKnownBits(C
, SQ
.DL
);
4766 unsigned MinLeadZero
= Known
.countMinLeadingZeros();
4767 // If the value being shifted has at most lowest bit set we can fold.
4768 unsigned MaxActiveBits
= Known
.getBitWidth() - MinLeadZero
;
4769 if (MaxActiveBits
<= 1)
4771 // Precondition: NewShAmt u<= countLeadingZeros(C)
4772 if (NewShAmtSplat
&& NewShAmtSplat
->getUniqueInteger().ule(MinLeadZero
))
4775 if (auto *C
= dyn_cast
<Constant
>(WidestShift
->getOperand(0))) {
4776 KnownBits Known
= computeKnownBits(C
, SQ
.DL
);
4777 unsigned MinLeadZero
= Known
.countMinLeadingZeros();
4778 // If the value being shifted has at most lowest bit set we can fold.
4779 unsigned MaxActiveBits
= Known
.getBitWidth() - MinLeadZero
;
4780 if (MaxActiveBits
<= 1)
4782 // Precondition: ((WidestBitWidth-1)-NewShAmt) u<= countLeadingZeros(C)
4783 if (NewShAmtSplat
) {
4785 (WidestBitWidth
- 1) - NewShAmtSplat
->getUniqueInteger();
4786 if (AdjNewShAmt
.ule(MinLeadZero
))
4790 return false; // Can't tell if it's ok.
4796 // All good, we can do this fold.
4797 X
= Builder
.CreateZExt(X
, WidestTy
);
4798 Y
= Builder
.CreateZExt(Y
, WidestTy
);
4799 // The shift is the same that was for X.
4800 Value
*T0
= XShiftOpcode
== Instruction::BinaryOps::LShr
4801 ? Builder
.CreateLShr(X
, NewShAmt
)
4802 : Builder
.CreateShl(X
, NewShAmt
);
4803 Value
*T1
= Builder
.CreateAnd(T0
, Y
);
4804 return Builder
.CreateICmp(I
.getPredicate(), T1
,
4805 Constant::getNullValue(WidestTy
));
4810 /// ((x * y) ?/ x) != y
4812 /// @llvm.?mul.with.overflow(x, y) plus extraction of overflow bit
4813 /// Note that the comparison is commutative, while inverted (u>=, ==) predicate
4814 /// will mean that we are looking for the opposite answer.
4815 Value
*InstCombinerImpl::foldMultiplicationOverflowCheck(ICmpInst
&I
) {
4821 // Look for: (-1 u/ x) u</u>= y
4822 if (!I
.isEquality() &&
4823 match(&I
, m_c_ICmp(Pred
,
4824 m_CombineAnd(m_OneUse(m_UDiv(m_AllOnes(), m_Value(X
))),
4825 m_Instruction(Div
)),
4829 // Are we checking that overflow does not happen, or does happen?
4831 case ICmpInst::Predicate::ICMP_ULT
:
4832 NeedNegation
= false;
4834 case ICmpInst::Predicate::ICMP_UGE
:
4835 NeedNegation
= true;
4838 return nullptr; // Wrong predicate.
4840 } else // Look for: ((x * y) / x) !=/== y
4841 if (I
.isEquality() &&
4843 m_c_ICmp(Pred
, m_Value(Y
),
4845 m_OneUse(m_IDiv(m_CombineAnd(m_c_Mul(m_Deferred(Y
),
4847 m_Instruction(Mul
)),
4849 m_Instruction(Div
))))) {
4850 NeedNegation
= Pred
== ICmpInst::Predicate::ICMP_EQ
;
4854 BuilderTy::InsertPointGuard
Guard(Builder
);
4855 // If the pattern included (x * y), we'll want to insert new instructions
4856 // right before that original multiplication so that we can replace it.
4857 bool MulHadOtherUses
= Mul
&& !Mul
->hasOneUse();
4858 if (MulHadOtherUses
)
4859 Builder
.SetInsertPoint(Mul
);
4861 CallInst
*Call
= Builder
.CreateIntrinsic(
4862 Div
->getOpcode() == Instruction::UDiv
? Intrinsic::umul_with_overflow
4863 : Intrinsic::smul_with_overflow
,
4864 X
->getType(), {X
, Y
}, /*FMFSource=*/nullptr, "mul");
4866 // If the multiplication was used elsewhere, to ensure that we don't leave
4867 // "duplicate" instructions, replace uses of that original multiplication
4868 // with the multiplication result from the with.overflow intrinsic.
4869 if (MulHadOtherUses
)
4870 replaceInstUsesWith(*Mul
, Builder
.CreateExtractValue(Call
, 0, "mul.val"));
4872 Value
*Res
= Builder
.CreateExtractValue(Call
, 1, "mul.ov");
4873 if (NeedNegation
) // This technically increases instruction count.
4874 Res
= Builder
.CreateNot(Res
, "mul.not.ov");
4876 // If we replaced the mul, erase it. Do this after all uses of Builder,
4877 // as the mul is used as insertion point.
4878 if (MulHadOtherUses
)
4879 eraseInstFromFunction(*Mul
);
4884 static Instruction
*foldICmpXNegX(ICmpInst
&I
,
4885 InstCombiner::BuilderTy
&Builder
) {
4888 if (match(&I
, m_c_ICmp(Pred
, m_NSWNeg(m_Value(X
)), m_Deferred(X
)))) {
4890 if (ICmpInst::isSigned(Pred
))
4891 Pred
= ICmpInst::getSwappedPredicate(Pred
);
4892 else if (ICmpInst::isUnsigned(Pred
))
4893 Pred
= ICmpInst::getSignedPredicate(Pred
);
4894 // else for equality-comparisons just keep the predicate.
4896 return ICmpInst::Create(Instruction::ICmp
, Pred
, X
,
4897 Constant::getNullValue(X
->getType()), I
.getName());
4900 // A value is not equal to its negation unless that value is 0 or
4901 // MinSignedValue, ie: a != -a --> (a & MaxSignedVal) != 0
4902 if (match(&I
, m_c_ICmp(Pred
, m_OneUse(m_Neg(m_Value(X
))), m_Deferred(X
))) &&
4903 ICmpInst::isEquality(Pred
)) {
4904 Type
*Ty
= X
->getType();
4905 uint32_t BitWidth
= Ty
->getScalarSizeInBits();
4906 Constant
*MaxSignedVal
=
4907 ConstantInt::get(Ty
, APInt::getSignedMaxValue(BitWidth
));
4908 Value
*And
= Builder
.CreateAnd(X
, MaxSignedVal
);
4909 Constant
*Zero
= Constant::getNullValue(Ty
);
4910 return CmpInst::Create(Instruction::ICmp
, Pred
, And
, Zero
);
4916 static Instruction
*foldICmpAndXX(ICmpInst
&I
, const SimplifyQuery
&Q
,
4917 InstCombinerImpl
&IC
) {
4918 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1), *A
;
4919 // Normalize and operand as operand 0.
4920 CmpInst::Predicate Pred
= I
.getPredicate();
4921 if (match(Op1
, m_c_And(m_Specific(Op0
), m_Value()))) {
4922 std::swap(Op0
, Op1
);
4923 Pred
= ICmpInst::getSwappedPredicate(Pred
);
4926 if (!match(Op0
, m_c_And(m_Specific(Op1
), m_Value(A
))))
4929 // (icmp (X & Y) u< X --> (X & Y) != X
4930 if (Pred
== ICmpInst::ICMP_ULT
)
4931 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
, Op1
);
4933 // (icmp (X & Y) u>= X --> (X & Y) == X
4934 if (Pred
== ICmpInst::ICMP_UGE
)
4935 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
, Op1
);
4937 if (ICmpInst::isEquality(Pred
) && Op0
->hasOneUse()) {
4938 // icmp (X & Y) eq/ne Y --> (X | ~Y) eq/ne -1 if Y is freely invertible and
4939 // Y is non-constant. If Y is constant the `X & C == C` form is preferable
4940 // so don't do this fold.
4941 if (!match(Op1
, m_ImmConstant()))
4943 IC
.getFreelyInverted(Op1
, !Op1
->hasNUsesOrMore(3), &IC
.Builder
))
4944 return new ICmpInst(Pred
, IC
.Builder
.CreateOr(A
, NotOp1
),
4945 Constant::getAllOnesValue(Op1
->getType()));
4946 // icmp (X & Y) eq/ne Y --> (~X & Y) eq/ne 0 if X is freely invertible.
4947 if (auto *NotA
= IC
.getFreelyInverted(A
, A
->hasOneUse(), &IC
.Builder
))
4948 return new ICmpInst(Pred
, IC
.Builder
.CreateAnd(Op1
, NotA
),
4949 Constant::getNullValue(Op1
->getType()));
4952 if (!ICmpInst::isSigned(Pred
))
4955 KnownBits KnownY
= IC
.computeKnownBits(A
, /*Depth=*/0, &I
);
4956 // (X & NegY) spred X --> (X & NegY) upred X
4957 if (KnownY
.isNegative())
4958 return new ICmpInst(ICmpInst::getUnsignedPredicate(Pred
), Op0
, Op1
);
4960 if (Pred
!= ICmpInst::ICMP_SLE
&& Pred
!= ICmpInst::ICMP_SGT
)
4963 if (KnownY
.isNonNegative())
4964 // (X & PosY) s<= X --> X s>= 0
4965 // (X & PosY) s> X --> X s< 0
4966 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), Op1
,
4967 Constant::getNullValue(Op1
->getType()));
4969 if (isKnownNegative(Op1
, IC
.getSimplifyQuery().getWithInstruction(&I
)))
4970 // (NegX & Y) s<= NegX --> Y s< 0
4971 // (NegX & Y) s> NegX --> Y s>= 0
4972 return new ICmpInst(ICmpInst::getFlippedStrictnessPredicate(Pred
), A
,
4973 Constant::getNullValue(A
->getType()));
4978 static Instruction
*foldICmpOrXX(ICmpInst
&I
, const SimplifyQuery
&Q
,
4979 InstCombinerImpl
&IC
) {
4980 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1), *A
;
4982 // Normalize or operand as operand 0.
4983 CmpInst::Predicate Pred
= I
.getPredicate();
4984 if (match(Op1
, m_c_Or(m_Specific(Op0
), m_Value(A
)))) {
4985 std::swap(Op0
, Op1
);
4986 Pred
= ICmpInst::getSwappedPredicate(Pred
);
4987 } else if (!match(Op0
, m_c_Or(m_Specific(Op1
), m_Value(A
)))) {
4991 // icmp (X | Y) u<= X --> (X | Y) == X
4992 if (Pred
== ICmpInst::ICMP_ULE
)
4993 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
, Op1
);
4995 // icmp (X | Y) u> X --> (X | Y) != X
4996 if (Pred
== ICmpInst::ICMP_UGT
)
4997 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
, Op1
);
4999 if (ICmpInst::isEquality(Pred
) && Op0
->hasOneUse()) {
5000 // icmp (X | Y) eq/ne Y --> (X & ~Y) eq/ne 0 if Y is freely invertible
5002 IC
.getFreelyInverted(Op1
, !Op1
->hasNUsesOrMore(3), &IC
.Builder
))
5003 return new ICmpInst(Pred
, IC
.Builder
.CreateAnd(A
, NotOp1
),
5004 Constant::getNullValue(Op1
->getType()));
5005 // icmp (X | Y) eq/ne Y --> (~X | Y) eq/ne -1 if X is freely invertible.
5006 if (Value
*NotA
= IC
.getFreelyInverted(A
, A
->hasOneUse(), &IC
.Builder
))
5007 return new ICmpInst(Pred
, IC
.Builder
.CreateOr(Op1
, NotA
),
5008 Constant::getAllOnesValue(Op1
->getType()));
5013 static Instruction
*foldICmpXorXX(ICmpInst
&I
, const SimplifyQuery
&Q
,
5014 InstCombinerImpl
&IC
) {
5015 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1), *A
;
5016 // Normalize xor operand as operand 0.
5017 CmpInst::Predicate Pred
= I
.getPredicate();
5018 if (match(Op1
, m_c_Xor(m_Specific(Op0
), m_Value()))) {
5019 std::swap(Op0
, Op1
);
5020 Pred
= ICmpInst::getSwappedPredicate(Pred
);
5022 if (!match(Op0
, m_c_Xor(m_Specific(Op1
), m_Value(A
))))
5025 // icmp (X ^ Y_NonZero) u>= X --> icmp (X ^ Y_NonZero) u> X
5026 // icmp (X ^ Y_NonZero) u<= X --> icmp (X ^ Y_NonZero) u< X
5027 // icmp (X ^ Y_NonZero) s>= X --> icmp (X ^ Y_NonZero) s> X
5028 // icmp (X ^ Y_NonZero) s<= X --> icmp (X ^ Y_NonZero) s< X
5029 CmpInst::Predicate PredOut
= CmpInst::getStrictPredicate(Pred
);
5030 if (PredOut
!= Pred
&& isKnownNonZero(A
, Q
))
5031 return new ICmpInst(PredOut
, Op0
, Op1
);
5036 /// Try to fold icmp (binop), X or icmp X, (binop).
5037 /// TODO: A large part of this logic is duplicated in InstSimplify's
5038 /// simplifyICmpWithBinOp(). We should be able to share that and avoid the code
5040 Instruction
*InstCombinerImpl::foldICmpBinOp(ICmpInst
&I
,
5041 const SimplifyQuery
&SQ
) {
5042 const SimplifyQuery Q
= SQ
.getWithInstruction(&I
);
5043 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
5045 // Special logic for binary operators.
5046 BinaryOperator
*BO0
= dyn_cast
<BinaryOperator
>(Op0
);
5047 BinaryOperator
*BO1
= dyn_cast
<BinaryOperator
>(Op1
);
5051 if (Instruction
*NewICmp
= foldICmpXNegX(I
, Builder
))
5054 const CmpInst::Predicate Pred
= I
.getPredicate();
5057 // Convert add-with-unsigned-overflow comparisons into a 'not' with compare.
5058 // (Op1 + X) u</u>= Op1 --> ~Op1 u</u>= X
5059 if (match(Op0
, m_OneUse(m_c_Add(m_Specific(Op1
), m_Value(X
)))) &&
5060 (Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_UGE
))
5061 return new ICmpInst(Pred
, Builder
.CreateNot(Op1
), X
);
5062 // Op0 u>/u<= (Op0 + X) --> X u>/u<= ~Op0
5063 if (match(Op1
, m_OneUse(m_c_Add(m_Specific(Op0
), m_Value(X
)))) &&
5064 (Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_ULE
))
5065 return new ICmpInst(Pred
, X
, Builder
.CreateNot(Op0
));
5068 // (Op1 + X) + C u</u>= Op1 --> ~C - X u</u>= Op1
5070 if (match(Op0
, m_OneUse(m_Add(m_c_Add(m_Specific(Op1
), m_Value(X
)),
5071 m_ImmConstant(C
)))) &&
5072 (Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_UGE
)) {
5073 Constant
*C2
= ConstantExpr::getNot(C
);
5074 return new ICmpInst(Pred
, Builder
.CreateSub(C2
, X
), Op1
);
5076 // Op0 u>/u<= (Op0 + X) + C --> Op0 u>/u<= ~C - X
5077 if (match(Op1
, m_OneUse(m_Add(m_c_Add(m_Specific(Op0
), m_Value(X
)),
5078 m_ImmConstant(C
)))) &&
5079 (Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_ULE
)) {
5080 Constant
*C2
= ConstantExpr::getNot(C
);
5081 return new ICmpInst(Pred
, Op0
, Builder
.CreateSub(C2
, X
));
5085 // (icmp eq/ne (X, -P2), INT_MIN)
5086 // -> (icmp slt/sge X, INT_MIN + P2)
5087 if (ICmpInst::isEquality(Pred
) && BO0
&&
5088 match(I
.getOperand(1), m_SignMask()) &&
5089 match(BO0
, m_And(m_Value(), m_NegatedPower2OrZero()))) {
5090 // Will Constant fold.
5091 Value
*NewC
= Builder
.CreateSub(I
.getOperand(1), BO0
->getOperand(1));
5092 return new ICmpInst(Pred
== ICmpInst::ICMP_EQ
? ICmpInst::ICMP_SLT
5093 : ICmpInst::ICMP_SGE
,
5094 BO0
->getOperand(0), NewC
);
5098 // Similar to above: an unsigned overflow comparison may use offset + mask:
5099 // ((Op1 + C) & C) u< Op1 --> Op1 != 0
5100 // ((Op1 + C) & C) u>= Op1 --> Op1 == 0
5101 // Op0 u> ((Op0 + C) & C) --> Op0 != 0
5102 // Op0 u<= ((Op0 + C) & C) --> Op0 == 0
5105 if ((Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_UGE
) &&
5106 match(Op0
, m_And(m_BinOp(BO
), m_LowBitMask(C
))) &&
5107 match(BO
, m_Add(m_Specific(Op1
), m_SpecificIntAllowPoison(*C
)))) {
5108 CmpInst::Predicate NewPred
=
5109 Pred
== ICmpInst::ICMP_ULT
? ICmpInst::ICMP_NE
: ICmpInst::ICMP_EQ
;
5110 Constant
*Zero
= ConstantInt::getNullValue(Op1
->getType());
5111 return new ICmpInst(NewPred
, Op1
, Zero
);
5114 if ((Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_ULE
) &&
5115 match(Op1
, m_And(m_BinOp(BO
), m_LowBitMask(C
))) &&
5116 match(BO
, m_Add(m_Specific(Op0
), m_SpecificIntAllowPoison(*C
)))) {
5117 CmpInst::Predicate NewPred
=
5118 Pred
== ICmpInst::ICMP_UGT
? ICmpInst::ICMP_NE
: ICmpInst::ICMP_EQ
;
5119 Constant
*Zero
= ConstantInt::getNullValue(Op1
->getType());
5120 return new ICmpInst(NewPred
, Op0
, Zero
);
5124 bool NoOp0WrapProblem
= false, NoOp1WrapProblem
= false;
5125 bool Op0HasNUW
= false, Op1HasNUW
= false;
5126 bool Op0HasNSW
= false, Op1HasNSW
= false;
5127 // Analyze the case when either Op0 or Op1 is an add instruction.
5128 // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
5129 auto hasNoWrapProblem
= [](const BinaryOperator
&BO
, CmpInst::Predicate Pred
,
5130 bool &HasNSW
, bool &HasNUW
) -> bool {
5131 if (isa
<OverflowingBinaryOperator
>(BO
)) {
5132 HasNUW
= BO
.hasNoUnsignedWrap();
5133 HasNSW
= BO
.hasNoSignedWrap();
5134 return ICmpInst::isEquality(Pred
) ||
5135 (CmpInst::isUnsigned(Pred
) && HasNUW
) ||
5136 (CmpInst::isSigned(Pred
) && HasNSW
);
5137 } else if (BO
.getOpcode() == Instruction::Or
) {
5145 Value
*A
= nullptr, *B
= nullptr, *C
= nullptr, *D
= nullptr;
5148 match(BO0
, m_AddLike(m_Value(A
), m_Value(B
)));
5149 NoOp0WrapProblem
= hasNoWrapProblem(*BO0
, Pred
, Op0HasNSW
, Op0HasNUW
);
5152 match(BO1
, m_AddLike(m_Value(C
), m_Value(D
)));
5153 NoOp1WrapProblem
= hasNoWrapProblem(*BO1
, Pred
, Op1HasNSW
, Op1HasNUW
);
5156 // icmp (A+B), A -> icmp B, 0 for equalities or if there is no overflow.
5157 // icmp (A+B), B -> icmp A, 0 for equalities or if there is no overflow.
5158 if ((A
== Op1
|| B
== Op1
) && NoOp0WrapProblem
)
5159 return new ICmpInst(Pred
, A
== Op1
? B
: A
,
5160 Constant::getNullValue(Op1
->getType()));
5162 // icmp C, (C+D) -> icmp 0, D for equalities or if there is no overflow.
5163 // icmp D, (C+D) -> icmp 0, C for equalities or if there is no overflow.
5164 if ((C
== Op0
|| D
== Op0
) && NoOp1WrapProblem
)
5165 return new ICmpInst(Pred
, Constant::getNullValue(Op0
->getType()),
5168 // icmp (A+B), (A+D) -> icmp B, D for equalities or if there is no overflow.
5169 if (A
&& C
&& (A
== C
|| A
== D
|| B
== C
|| B
== D
) && NoOp0WrapProblem
&&
5171 // Determine Y and Z in the form icmp (X+Y), (X+Z).
5174 // C + B == C + D -> B == D
5177 } else if (A
== D
) {
5178 // D + B == C + D -> B == C
5181 } else if (B
== C
) {
5182 // A + C == C + D -> A == D
5187 // A + D == C + D -> A == C
5191 return new ICmpInst(Pred
, Y
, Z
);
5194 // icmp slt (A + -1), Op1 -> icmp sle A, Op1
5195 if (A
&& NoOp0WrapProblem
&& Pred
== CmpInst::ICMP_SLT
&&
5196 match(B
, m_AllOnes()))
5197 return new ICmpInst(CmpInst::ICMP_SLE
, A
, Op1
);
5199 // icmp sge (A + -1), Op1 -> icmp sgt A, Op1
5200 if (A
&& NoOp0WrapProblem
&& Pred
== CmpInst::ICMP_SGE
&&
5201 match(B
, m_AllOnes()))
5202 return new ICmpInst(CmpInst::ICMP_SGT
, A
, Op1
);
5204 // icmp sle (A + 1), Op1 -> icmp slt A, Op1
5205 if (A
&& NoOp0WrapProblem
&& Pred
== CmpInst::ICMP_SLE
&& match(B
, m_One()))
5206 return new ICmpInst(CmpInst::ICMP_SLT
, A
, Op1
);
5208 // icmp sgt (A + 1), Op1 -> icmp sge A, Op1
5209 if (A
&& NoOp0WrapProblem
&& Pred
== CmpInst::ICMP_SGT
&& match(B
, m_One()))
5210 return new ICmpInst(CmpInst::ICMP_SGE
, A
, Op1
);
5212 // icmp sgt Op0, (C + -1) -> icmp sge Op0, C
5213 if (C
&& NoOp1WrapProblem
&& Pred
== CmpInst::ICMP_SGT
&&
5214 match(D
, m_AllOnes()))
5215 return new ICmpInst(CmpInst::ICMP_SGE
, Op0
, C
);
5217 // icmp sle Op0, (C + -1) -> icmp slt Op0, C
5218 if (C
&& NoOp1WrapProblem
&& Pred
== CmpInst::ICMP_SLE
&&
5219 match(D
, m_AllOnes()))
5220 return new ICmpInst(CmpInst::ICMP_SLT
, Op0
, C
);
5222 // icmp sge Op0, (C + 1) -> icmp sgt Op0, C
5223 if (C
&& NoOp1WrapProblem
&& Pred
== CmpInst::ICMP_SGE
&& match(D
, m_One()))
5224 return new ICmpInst(CmpInst::ICMP_SGT
, Op0
, C
);
5226 // icmp slt Op0, (C + 1) -> icmp sle Op0, C
5227 if (C
&& NoOp1WrapProblem
&& Pred
== CmpInst::ICMP_SLT
&& match(D
, m_One()))
5228 return new ICmpInst(CmpInst::ICMP_SLE
, Op0
, C
);
5230 // TODO: The subtraction-related identities shown below also hold, but
5231 // canonicalization from (X -nuw 1) to (X + -1) means that the combinations
5232 // wouldn't happen even if they were implemented.
5234 // icmp ult (A - 1), Op1 -> icmp ule A, Op1
5235 // icmp uge (A - 1), Op1 -> icmp ugt A, Op1
5236 // icmp ugt Op0, (C - 1) -> icmp uge Op0, C
5237 // icmp ule Op0, (C - 1) -> icmp ult Op0, C
5239 // icmp ule (A + 1), Op0 -> icmp ult A, Op1
5240 if (A
&& NoOp0WrapProblem
&& Pred
== CmpInst::ICMP_ULE
&& match(B
, m_One()))
5241 return new ICmpInst(CmpInst::ICMP_ULT
, A
, Op1
);
5243 // icmp ugt (A + 1), Op0 -> icmp uge A, Op1
5244 if (A
&& NoOp0WrapProblem
&& Pred
== CmpInst::ICMP_UGT
&& match(B
, m_One()))
5245 return new ICmpInst(CmpInst::ICMP_UGE
, A
, Op1
);
5247 // icmp uge Op0, (C + 1) -> icmp ugt Op0, C
5248 if (C
&& NoOp1WrapProblem
&& Pred
== CmpInst::ICMP_UGE
&& match(D
, m_One()))
5249 return new ICmpInst(CmpInst::ICMP_UGT
, Op0
, C
);
5251 // icmp ult Op0, (C + 1) -> icmp ule Op0, C
5252 if (C
&& NoOp1WrapProblem
&& Pred
== CmpInst::ICMP_ULT
&& match(D
, m_One()))
5253 return new ICmpInst(CmpInst::ICMP_ULE
, Op0
, C
);
5255 // if C1 has greater magnitude than C2:
5256 // icmp (A + C1), (C + C2) -> icmp (A + C3), C
5257 // s.t. C3 = C1 - C2
5259 // if C2 has greater magnitude than C1:
5260 // icmp (A + C1), (C + C2) -> icmp A, (C + C3)
5261 // s.t. C3 = C2 - C1
5262 if (A
&& C
&& NoOp0WrapProblem
&& NoOp1WrapProblem
&&
5263 (BO0
->hasOneUse() || BO1
->hasOneUse()) && !I
.isUnsigned()) {
5264 const APInt
*AP1
, *AP2
;
5265 // TODO: Support non-uniform vectors.
5266 // TODO: Allow poison passthrough if B or D's element is poison.
5267 if (match(B
, m_APIntAllowPoison(AP1
)) &&
5268 match(D
, m_APIntAllowPoison(AP2
)) &&
5269 AP1
->isNegative() == AP2
->isNegative()) {
5270 APInt AP1Abs
= AP1
->abs();
5271 APInt AP2Abs
= AP2
->abs();
5272 if (AP1Abs
.uge(AP2Abs
)) {
5273 APInt Diff
= *AP1
- *AP2
;
5274 Constant
*C3
= Constant::getIntegerValue(BO0
->getType(), Diff
);
5275 Value
*NewAdd
= Builder
.CreateAdd(
5276 A
, C3
, "", Op0HasNUW
&& Diff
.ule(*AP1
), Op0HasNSW
);
5277 return new ICmpInst(Pred
, NewAdd
, C
);
5279 APInt Diff
= *AP2
- *AP1
;
5280 Constant
*C3
= Constant::getIntegerValue(BO0
->getType(), Diff
);
5281 Value
*NewAdd
= Builder
.CreateAdd(
5282 C
, C3
, "", Op1HasNUW
&& Diff
.ule(*AP2
), Op1HasNSW
);
5283 return new ICmpInst(Pred
, A
, NewAdd
);
5286 Constant
*Cst1
, *Cst2
;
5287 if (match(B
, m_ImmConstant(Cst1
)) && match(D
, m_ImmConstant(Cst2
)) &&
5288 ICmpInst::isEquality(Pred
)) {
5289 Constant
*Diff
= ConstantExpr::getSub(Cst2
, Cst1
);
5290 Value
*NewAdd
= Builder
.CreateAdd(C
, Diff
);
5291 return new ICmpInst(Pred
, A
, NewAdd
);
5295 // Analyze the case when either Op0 or Op1 is a sub instruction.
5296 // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
5301 if (BO0
&& BO0
->getOpcode() == Instruction::Sub
) {
5302 A
= BO0
->getOperand(0);
5303 B
= BO0
->getOperand(1);
5305 if (BO1
&& BO1
->getOpcode() == Instruction::Sub
) {
5306 C
= BO1
->getOperand(0);
5307 D
= BO1
->getOperand(1);
5310 // icmp (A-B), A -> icmp 0, B for equalities or if there is no overflow.
5311 if (A
== Op1
&& NoOp0WrapProblem
)
5312 return new ICmpInst(Pred
, Constant::getNullValue(Op1
->getType()), B
);
5313 // icmp C, (C-D) -> icmp D, 0 for equalities or if there is no overflow.
5314 if (C
== Op0
&& NoOp1WrapProblem
)
5315 return new ICmpInst(Pred
, D
, Constant::getNullValue(Op0
->getType()));
5317 // Convert sub-with-unsigned-overflow comparisons into a comparison of args.
5318 // (A - B) u>/u<= A --> B u>/u<= A
5319 if (A
== Op1
&& (Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_ULE
))
5320 return new ICmpInst(Pred
, B
, A
);
5321 // C u</u>= (C - D) --> C u</u>= D
5322 if (C
== Op0
&& (Pred
== ICmpInst::ICMP_ULT
|| Pred
== ICmpInst::ICMP_UGE
))
5323 return new ICmpInst(Pred
, C
, D
);
5324 // (A - B) u>=/u< A --> B u>/u<= A iff B != 0
5325 if (A
== Op1
&& (Pred
== ICmpInst::ICMP_UGE
|| Pred
== ICmpInst::ICMP_ULT
) &&
5326 isKnownNonZero(B
, Q
))
5327 return new ICmpInst(CmpInst::getFlippedStrictnessPredicate(Pred
), B
, A
);
5328 // C u<=/u> (C - D) --> C u</u>= D iff B != 0
5329 if (C
== Op0
&& (Pred
== ICmpInst::ICMP_ULE
|| Pred
== ICmpInst::ICMP_UGT
) &&
5330 isKnownNonZero(D
, Q
))
5331 return new ICmpInst(CmpInst::getFlippedStrictnessPredicate(Pred
), C
, D
);
5333 // icmp (A-B), (C-B) -> icmp A, C for equalities or if there is no overflow.
5334 if (B
&& D
&& B
== D
&& NoOp0WrapProblem
&& NoOp1WrapProblem
)
5335 return new ICmpInst(Pred
, A
, C
);
5337 // icmp (A-B), (A-D) -> icmp D, B for equalities or if there is no overflow.
5338 if (A
&& C
&& A
== C
&& NoOp0WrapProblem
&& NoOp1WrapProblem
)
5339 return new ICmpInst(Pred
, D
, B
);
5341 // icmp (0-X) < cst --> x > -cst
5342 if (NoOp0WrapProblem
&& ICmpInst::isSigned(Pred
)) {
5344 if (match(BO0
, m_Neg(m_Value(X
))))
5345 if (Constant
*RHSC
= dyn_cast
<Constant
>(Op1
))
5346 if (RHSC
->isNotMinSignedValue())
5347 return new ICmpInst(I
.getSwappedPredicate(), X
,
5348 ConstantExpr::getNeg(RHSC
));
5351 if (Instruction
* R
= foldICmpXorXX(I
, Q
, *this))
5353 if (Instruction
*R
= foldICmpOrXX(I
, Q
, *this))
5357 // Try to remove shared multiplier from comparison:
5360 if ((match(Op0
, m_Mul(m_Value(X
), m_Value(Z
))) &&
5361 match(Op1
, m_c_Mul(m_Specific(Z
), m_Value(Y
)))) ||
5362 (match(Op0
, m_Mul(m_Value(Z
), m_Value(X
))) &&
5363 match(Op1
, m_c_Mul(m_Specific(Z
), m_Value(Y
))))) {
5364 if (ICmpInst::isSigned(Pred
)) {
5365 if (Op0HasNSW
&& Op1HasNSW
) {
5366 KnownBits ZKnown
= computeKnownBits(Z
, 0, &I
);
5367 if (ZKnown
.isStrictlyPositive())
5368 return new ICmpInst(Pred
, X
, Y
);
5369 if (ZKnown
.isNegative())
5370 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), X
, Y
);
5371 Value
*LessThan
= simplifyICmpInst(ICmpInst::ICMP_SLT
, X
, Y
,
5372 SQ
.getWithInstruction(&I
));
5373 if (LessThan
&& match(LessThan
, m_One()))
5374 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), Z
,
5375 Constant::getNullValue(Z
->getType()));
5376 Value
*GreaterThan
= simplifyICmpInst(ICmpInst::ICMP_SGT
, X
, Y
,
5377 SQ
.getWithInstruction(&I
));
5378 if (GreaterThan
&& match(GreaterThan
, m_One()))
5379 return new ICmpInst(Pred
, Z
, Constant::getNullValue(Z
->getType()));
5383 if (ICmpInst::isEquality(Pred
)) {
5384 // If X != Y, fold (X *nw Z) eq/ne (Y *nw Z) -> Z eq/ne 0
5385 if (((Op0HasNSW
&& Op1HasNSW
) || (Op0HasNUW
&& Op1HasNUW
)) &&
5386 isKnownNonEqual(X
, Y
, DL
, &AC
, &I
, &DT
))
5387 return new ICmpInst(Pred
, Z
, Constant::getNullValue(Z
->getType()));
5389 KnownBits ZKnown
= computeKnownBits(Z
, 0, &I
);
5391 // X * Z eq/ne Y * Z -> X eq/ne Y
5392 if (ZKnown
.countMaxTrailingZeros() == 0)
5393 return new ICmpInst(Pred
, X
, Y
);
5394 NonZero
= !ZKnown
.One
.isZero() || isKnownNonZero(Z
, Q
);
5395 // if Z != 0 and nsw(X * Z) and nsw(Y * Z)
5396 // X * Z eq/ne Y * Z -> X eq/ne Y
5397 if (NonZero
&& BO0
&& BO1
&& Op0HasNSW
&& Op1HasNSW
)
5398 return new ICmpInst(Pred
, X
, Y
);
5400 NonZero
= isKnownNonZero(Z
, Q
);
5402 // If Z != 0 and nuw(X * Z) and nuw(Y * Z)
5403 // X * Z u{lt/le/gt/ge}/eq/ne Y * Z -> X u{lt/le/gt/ge}/eq/ne Y
5404 if (NonZero
&& BO0
&& BO1
&& Op0HasNUW
&& Op1HasNUW
)
5405 return new ICmpInst(Pred
, X
, Y
);
5410 BinaryOperator
*SRem
= nullptr;
5411 // icmp (srem X, Y), Y
5412 if (BO0
&& BO0
->getOpcode() == Instruction::SRem
&& Op1
== BO0
->getOperand(1))
5414 // icmp Y, (srem X, Y)
5415 else if (BO1
&& BO1
->getOpcode() == Instruction::SRem
&&
5416 Op0
== BO1
->getOperand(1))
5419 // We don't check hasOneUse to avoid increasing register pressure because
5420 // the value we use is the same value this instruction was already using.
5421 switch (SRem
== BO0
? ICmpInst::getSwappedPredicate(Pred
) : Pred
) {
5424 case ICmpInst::ICMP_EQ
:
5425 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
5426 case ICmpInst::ICMP_NE
:
5427 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
5428 case ICmpInst::ICMP_SGT
:
5429 case ICmpInst::ICMP_SGE
:
5430 return new ICmpInst(ICmpInst::ICMP_SGT
, SRem
->getOperand(1),
5431 Constant::getAllOnesValue(SRem
->getType()));
5432 case ICmpInst::ICMP_SLT
:
5433 case ICmpInst::ICMP_SLE
:
5434 return new ICmpInst(ICmpInst::ICMP_SLT
, SRem
->getOperand(1),
5435 Constant::getNullValue(SRem
->getType()));
5439 if (BO0
&& BO1
&& BO0
->getOpcode() == BO1
->getOpcode() &&
5440 (BO0
->hasOneUse() || BO1
->hasOneUse()) &&
5441 BO0
->getOperand(1) == BO1
->getOperand(1)) {
5442 switch (BO0
->getOpcode()) {
5445 case Instruction::Add
:
5446 case Instruction::Sub
:
5447 case Instruction::Xor
: {
5448 if (I
.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
5449 return new ICmpInst(Pred
, BO0
->getOperand(0), BO1
->getOperand(0));
5452 if (match(BO0
->getOperand(1), m_APInt(C
))) {
5453 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
5454 if (C
->isSignMask()) {
5455 ICmpInst::Predicate NewPred
= I
.getFlippedSignednessPredicate();
5456 return new ICmpInst(NewPred
, BO0
->getOperand(0), BO1
->getOperand(0));
5459 // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b
5460 if (BO0
->getOpcode() == Instruction::Xor
&& C
->isMaxSignedValue()) {
5461 ICmpInst::Predicate NewPred
= I
.getFlippedSignednessPredicate();
5462 NewPred
= I
.getSwappedPredicate(NewPred
);
5463 return new ICmpInst(NewPred
, BO0
->getOperand(0), BO1
->getOperand(0));
5468 case Instruction::Mul
: {
5469 if (!I
.isEquality())
5473 if (match(BO0
->getOperand(1), m_APInt(C
)) && !C
->isZero() &&
5475 // icmp eq/ne (X * C), (Y * C) --> icmp (X & Mask), (Y & Mask)
5476 // Mask = -1 >> count-trailing-zeros(C).
5477 if (unsigned TZs
= C
->countr_zero()) {
5478 Constant
*Mask
= ConstantInt::get(
5480 APInt::getLowBitsSet(C
->getBitWidth(), C
->getBitWidth() - TZs
));
5481 Value
*And1
= Builder
.CreateAnd(BO0
->getOperand(0), Mask
);
5482 Value
*And2
= Builder
.CreateAnd(BO1
->getOperand(0), Mask
);
5483 return new ICmpInst(Pred
, And1
, And2
);
5488 case Instruction::UDiv
:
5489 case Instruction::LShr
:
5490 if (I
.isSigned() || !BO0
->isExact() || !BO1
->isExact())
5492 return new ICmpInst(Pred
, BO0
->getOperand(0), BO1
->getOperand(0));
5494 case Instruction::SDiv
:
5495 if (!(I
.isEquality() || match(BO0
->getOperand(1), m_NonNegative())) ||
5496 !BO0
->isExact() || !BO1
->isExact())
5498 return new ICmpInst(Pred
, BO0
->getOperand(0), BO1
->getOperand(0));
5500 case Instruction::AShr
:
5501 if (!BO0
->isExact() || !BO1
->isExact())
5503 return new ICmpInst(Pred
, BO0
->getOperand(0), BO1
->getOperand(0));
5505 case Instruction::Shl
: {
5506 bool NUW
= Op0HasNUW
&& Op1HasNUW
;
5507 bool NSW
= Op0HasNSW
&& Op1HasNSW
;
5510 if (!NSW
&& I
.isSigned())
5512 return new ICmpInst(Pred
, BO0
->getOperand(0), BO1
->getOperand(0));
5518 // Transform A & (L - 1) `ult` L --> L != 0
5519 auto LSubOne
= m_Add(m_Specific(Op1
), m_AllOnes());
5520 auto BitwiseAnd
= m_c_And(m_Value(), LSubOne
);
5522 if (match(BO0
, BitwiseAnd
) && Pred
== ICmpInst::ICMP_ULT
) {
5523 auto *Zero
= Constant::getNullValue(BO0
->getType());
5524 return new ICmpInst(ICmpInst::ICMP_NE
, Op1
, Zero
);
5528 // For unsigned predicates / eq / ne:
5529 // icmp pred (x << 1), x --> icmp getSignedPredicate(pred) x, 0
5530 // icmp pred x, (x << 1) --> icmp getSignedPredicate(pred) 0, x
5531 if (!ICmpInst::isSigned(Pred
)) {
5532 if (match(Op0
, m_Shl(m_Specific(Op1
), m_One())))
5533 return new ICmpInst(ICmpInst::getSignedPredicate(Pred
), Op1
,
5534 Constant::getNullValue(Op1
->getType()));
5535 else if (match(Op1
, m_Shl(m_Specific(Op0
), m_One())))
5536 return new ICmpInst(ICmpInst::getSignedPredicate(Pred
),
5537 Constant::getNullValue(Op0
->getType()), Op0
);
5540 if (Value
*V
= foldMultiplicationOverflowCheck(I
))
5541 return replaceInstUsesWith(I
, V
);
5543 if (Instruction
*R
= foldICmpAndXX(I
, Q
, *this))
5546 if (Value
*V
= foldICmpWithTruncSignExtendedVal(I
, Builder
))
5547 return replaceInstUsesWith(I
, V
);
5549 if (Value
*V
= foldShiftIntoShiftInAnotherHandOfAndInICmp(I
, SQ
, Builder
))
5550 return replaceInstUsesWith(I
, V
);
5555 /// Fold icmp Pred min|max(X, Y), Z.
5556 Instruction
*InstCombinerImpl::foldICmpWithMinMax(Instruction
&I
,
5557 MinMaxIntrinsic
*MinMax
,
5558 Value
*Z
, CmpPredicate Pred
) {
5559 Value
*X
= MinMax
->getLHS();
5560 Value
*Y
= MinMax
->getRHS();
5561 if (ICmpInst::isSigned(Pred
) && !MinMax
->isSigned())
5563 if (ICmpInst::isUnsigned(Pred
) && MinMax
->isSigned()) {
5564 // Revert the transform signed pred -> unsigned pred
5565 // TODO: We can flip the signedness of predicate if both operands of icmp
5567 if (isKnownNonNegative(Z
, SQ
.getWithInstruction(&I
)) &&
5568 isKnownNonNegative(MinMax
, SQ
.getWithInstruction(&I
))) {
5569 Pred
= ICmpInst::getFlippedSignednessPredicate(Pred
);
5573 SimplifyQuery Q
= SQ
.getWithInstruction(&I
);
5574 auto IsCondKnownTrue
= [](Value
*Val
) -> std::optional
<bool> {
5576 return std::nullopt
;
5577 if (match(Val
, m_One()))
5579 if (match(Val
, m_Zero()))
5581 return std::nullopt
;
5583 auto CmpXZ
= IsCondKnownTrue(simplifyICmpInst(Pred
, X
, Z
, Q
));
5584 auto CmpYZ
= IsCondKnownTrue(simplifyICmpInst(Pred
, Y
, Z
, Q
));
5585 if (!CmpXZ
.has_value() && !CmpYZ
.has_value())
5587 if (!CmpXZ
.has_value()) {
5589 std::swap(CmpXZ
, CmpYZ
);
5592 auto FoldIntoCmpYZ
= [&]() -> Instruction
* {
5593 if (CmpYZ
.has_value())
5594 return replaceInstUsesWith(I
, ConstantInt::getBool(I
.getType(), *CmpYZ
));
5595 return ICmpInst::Create(Instruction::ICmp
, Pred
, Y
, Z
);
5599 case ICmpInst::ICMP_EQ
:
5600 case ICmpInst::ICMP_NE
: {
5603 // min(X, Y) == Z X <= Y
5604 // max(X, Y) == Z X >= Y
5605 // min(X, Y) != Z X > Y
5606 // max(X, Y) != Z X < Y
5607 if ((Pred
== ICmpInst::ICMP_EQ
) == *CmpXZ
) {
5608 ICmpInst::Predicate NewPred
=
5609 ICmpInst::getNonStrictPredicate(MinMax
->getPredicate());
5610 if (Pred
== ICmpInst::ICMP_NE
)
5611 NewPred
= ICmpInst::getInversePredicate(NewPred
);
5612 return ICmpInst::Create(Instruction::ICmp
, NewPred
, X
, Y
);
5614 // Otherwise (X != Z):
5615 ICmpInst::Predicate NewPred
= MinMax
->getPredicate();
5616 auto MinMaxCmpXZ
= IsCondKnownTrue(simplifyICmpInst(NewPred
, X
, Z
, Q
));
5617 if (!MinMaxCmpXZ
.has_value()) {
5619 std::swap(CmpXZ
, CmpYZ
);
5620 // Re-check pre-condition X != Z
5621 if (!CmpXZ
.has_value() || (Pred
== ICmpInst::ICMP_EQ
) == *CmpXZ
)
5623 MinMaxCmpXZ
= IsCondKnownTrue(simplifyICmpInst(NewPred
, X
, Z
, Q
));
5625 if (!MinMaxCmpXZ
.has_value())
5629 // min(X, Y) == Z X < Z false
5630 // max(X, Y) == Z X > Z false
5631 // min(X, Y) != Z X < Z true
5632 // max(X, Y) != Z X > Z true
5633 return replaceInstUsesWith(
5634 I
, ConstantInt::getBool(I
.getType(), Pred
== ICmpInst::ICMP_NE
));
5637 // min(X, Y) == Z X > Z Y == Z
5638 // max(X, Y) == Z X < Z Y == Z
5639 // min(X, Y) != Z X > Z Y != Z
5640 // max(X, Y) != Z X < Z Y != Z
5641 return FoldIntoCmpYZ();
5645 case ICmpInst::ICMP_SLT
:
5646 case ICmpInst::ICMP_ULT
:
5647 case ICmpInst::ICMP_SLE
:
5648 case ICmpInst::ICMP_ULE
:
5649 case ICmpInst::ICMP_SGT
:
5650 case ICmpInst::ICMP_UGT
:
5651 case ICmpInst::ICMP_SGE
:
5652 case ICmpInst::ICMP_UGE
: {
5653 bool IsSame
= MinMax
->getPredicate() == ICmpInst::getStrictPredicate(Pred
);
5657 // min(X, Y) < Z X < Z true
5658 // min(X, Y) <= Z X <= Z true
5659 // max(X, Y) > Z X > Z true
5660 // max(X, Y) >= Z X >= Z true
5661 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
5664 // max(X, Y) < Z X < Z Y < Z
5665 // max(X, Y) <= Z X <= Z Y <= Z
5666 // min(X, Y) > Z X > Z Y > Z
5667 // min(X, Y) >= Z X >= Z Y >= Z
5668 return FoldIntoCmpYZ();
5673 // min(X, Y) < Z X >= Z Y < Z
5674 // min(X, Y) <= Z X > Z Y <= Z
5675 // max(X, Y) > Z X <= Z Y > Z
5676 // max(X, Y) >= Z X < Z Y >= Z
5677 return FoldIntoCmpYZ();
5680 // max(X, Y) < Z X >= Z false
5681 // max(X, Y) <= Z X > Z false
5682 // min(X, Y) > Z X <= Z false
5683 // min(X, Y) >= Z X < Z false
5684 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
5696 // Canonicalize checking for a power-of-2-or-zero value:
5697 static Instruction
*foldICmpPow2Test(ICmpInst
&I
,
5698 InstCombiner::BuilderTy
&Builder
) {
5699 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
5700 const CmpInst::Predicate Pred
= I
.getPredicate();
5703 if (I
.isEquality()) {
5704 // (A & (A-1)) == 0 --> ctpop(A) < 2 (two commuted variants)
5705 // ((A-1) & A) != 0 --> ctpop(A) > 1 (two commuted variants)
5706 if (!match(Op0
, m_OneUse(m_c_And(m_Add(m_Value(A
), m_AllOnes()),
5708 !match(Op1
, m_ZeroInt()))
5711 // (A & -A) == A --> ctpop(A) < 2 (four commuted variants)
5712 // (-A & A) != A --> ctpop(A) > 1 (four commuted variants)
5713 if (match(Op0
, m_OneUse(m_c_And(m_Neg(m_Specific(Op1
)), m_Specific(Op1
)))))
5716 m_OneUse(m_c_And(m_Neg(m_Specific(Op0
)), m_Specific(Op0
)))))
5719 CheckIs
= Pred
== ICmpInst::ICMP_EQ
;
5720 } else if (ICmpInst::isUnsigned(Pred
)) {
5721 // (A ^ (A-1)) u>= A --> ctpop(A) < 2 (two commuted variants)
5722 // ((A-1) ^ A) u< A --> ctpop(A) > 1 (two commuted variants)
5724 if ((Pred
== ICmpInst::ICMP_UGE
|| Pred
== ICmpInst::ICMP_ULT
) &&
5725 match(Op0
, m_OneUse(m_c_Xor(m_Add(m_Specific(Op1
), m_AllOnes()),
5726 m_Specific(Op1
))))) {
5728 CheckIs
= Pred
== ICmpInst::ICMP_UGE
;
5729 } else if ((Pred
== ICmpInst::ICMP_UGT
|| Pred
== ICmpInst::ICMP_ULE
) &&
5730 match(Op1
, m_OneUse(m_c_Xor(m_Add(m_Specific(Op0
), m_AllOnes()),
5731 m_Specific(Op0
))))) {
5733 CheckIs
= Pred
== ICmpInst::ICMP_ULE
;
5738 Type
*Ty
= A
->getType();
5739 CallInst
*CtPop
= Builder
.CreateUnaryIntrinsic(Intrinsic::ctpop
, A
);
5740 return CheckIs
? new ICmpInst(ICmpInst::ICMP_ULT
, CtPop
,
5741 ConstantInt::get(Ty
, 2))
5742 : new ICmpInst(ICmpInst::ICMP_UGT
, CtPop
,
5743 ConstantInt::get(Ty
, 1));
5749 Instruction
*InstCombinerImpl::foldICmpEquality(ICmpInst
&I
) {
5750 if (!I
.isEquality())
5753 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
5754 const CmpInst::Predicate Pred
= I
.getPredicate();
5755 Value
*A
, *B
, *C
, *D
;
5756 if (match(Op0
, m_Xor(m_Value(A
), m_Value(B
)))) {
5757 if (A
== Op1
|| B
== Op1
) { // (A^B) == A -> B == 0
5758 Value
*OtherVal
= A
== Op1
? B
: A
;
5759 return new ICmpInst(Pred
, OtherVal
, Constant::getNullValue(A
->getType()));
5762 if (match(Op1
, m_Xor(m_Value(C
), m_Value(D
)))) {
5763 // A^c1 == C^c2 --> A == C^(c1^c2)
5764 ConstantInt
*C1
, *C2
;
5765 if (match(B
, m_ConstantInt(C1
)) && match(D
, m_ConstantInt(C2
)) &&
5767 Constant
*NC
= Builder
.getInt(C1
->getValue() ^ C2
->getValue());
5768 Value
*Xor
= Builder
.CreateXor(C
, NC
);
5769 return new ICmpInst(Pred
, A
, Xor
);
5772 // A^B == A^D -> B == D
5774 return new ICmpInst(Pred
, B
, D
);
5776 return new ICmpInst(Pred
, B
, C
);
5778 return new ICmpInst(Pred
, A
, D
);
5780 return new ICmpInst(Pred
, A
, C
);
5784 if (match(Op1
, m_Xor(m_Value(A
), m_Value(B
))) && (A
== Op0
|| B
== Op0
)) {
5785 // A == (A^B) -> B == 0
5786 Value
*OtherVal
= A
== Op0
? B
: A
;
5787 return new ICmpInst(Pred
, OtherVal
, Constant::getNullValue(A
->getType()));
5790 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
5791 if (match(Op0
, m_And(m_Value(A
), m_Value(B
))) &&
5792 match(Op1
, m_And(m_Value(C
), m_Value(D
)))) {
5793 Value
*X
= nullptr, *Y
= nullptr, *Z
= nullptr;
5799 } else if (A
== D
) {
5803 } else if (B
== C
) {
5807 } else if (B
== D
) {
5814 // If X^Y is a negative power of two, then `icmp eq/ne (Z & NegP2), 0`
5815 // will fold to `icmp ult/uge Z, -NegP2` incurringb no additional
5817 const APInt
*C0
, *C1
;
5818 bool XorIsNegP2
= match(X
, m_APInt(C0
)) && match(Y
, m_APInt(C1
)) &&
5819 (*C0
^ *C1
).isNegatedPowerOf2();
5821 // If either Op0/Op1 are both one use or X^Y will constant fold and one of
5822 // Op0/Op1 are one use, proceed. In those cases we are instruction neutral
5823 // but `icmp eq/ne A, 0` is easier to analyze than `icmp eq/ne A, B`.
5825 int(Op0
->hasOneUse()) + int(Op1
->hasOneUse()) +
5826 (int(match(X
, m_ImmConstant()) && match(Y
, m_ImmConstant())));
5827 if (XorIsNegP2
|| UseCnt
>= 2) {
5829 Op1
= Builder
.CreateXor(X
, Y
);
5830 Op1
= Builder
.CreateAnd(Op1
, Z
);
5831 return new ICmpInst(Pred
, Op1
, Constant::getNullValue(Op1
->getType()));
5837 // Similar to above, but specialized for constant because invert is needed:
5838 // (X | C) == (Y | C) --> (X ^ Y) & ~C == 0
5841 if (match(Op0
, m_OneUse(m_Or(m_Value(X
), m_Constant(C
)))) &&
5842 match(Op1
, m_OneUse(m_Or(m_Value(Y
), m_Specific(C
))))) {
5843 Value
*Xor
= Builder
.CreateXor(X
, Y
);
5844 Value
*And
= Builder
.CreateAnd(Xor
, ConstantExpr::getNot(C
));
5845 return new ICmpInst(Pred
, And
, Constant::getNullValue(And
->getType()));
5849 if (match(Op1
, m_ZExt(m_Value(A
))) &&
5850 (Op0
->hasOneUse() || Op1
->hasOneUse())) {
5851 // (B & (Pow2C-1)) == zext A --> A == trunc B
5852 // (B & (Pow2C-1)) != zext A --> A != trunc B
5854 if (match(Op0
, m_And(m_Value(B
), m_LowBitMask(MaskC
))) &&
5855 MaskC
->countr_one() == A
->getType()->getScalarSizeInBits())
5856 return new ICmpInst(Pred
, A
, Builder
.CreateTrunc(B
, A
->getType()));
5859 // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
5860 // For lshr and ashr pairs.
5861 const APInt
*AP1
, *AP2
;
5862 if ((match(Op0
, m_OneUse(m_LShr(m_Value(A
), m_APIntAllowPoison(AP1
)))) &&
5863 match(Op1
, m_OneUse(m_LShr(m_Value(B
), m_APIntAllowPoison(AP2
))))) ||
5864 (match(Op0
, m_OneUse(m_AShr(m_Value(A
), m_APIntAllowPoison(AP1
)))) &&
5865 match(Op1
, m_OneUse(m_AShr(m_Value(B
), m_APIntAllowPoison(AP2
)))))) {
5868 unsigned TypeBits
= AP1
->getBitWidth();
5869 unsigned ShAmt
= AP1
->getLimitedValue(TypeBits
);
5870 if (ShAmt
< TypeBits
&& ShAmt
!= 0) {
5871 ICmpInst::Predicate NewPred
=
5872 Pred
== ICmpInst::ICMP_NE
? ICmpInst::ICMP_UGE
: ICmpInst::ICMP_ULT
;
5873 Value
*Xor
= Builder
.CreateXor(A
, B
, I
.getName() + ".unshifted");
5874 APInt CmpVal
= APInt::getOneBitSet(TypeBits
, ShAmt
);
5875 return new ICmpInst(NewPred
, Xor
, ConstantInt::get(A
->getType(), CmpVal
));
5879 // (A << C) == (B << C) --> ((A^B) & (~0U >> C)) == 0
5881 if (match(Op0
, m_OneUse(m_Shl(m_Value(A
), m_ConstantInt(Cst1
)))) &&
5882 match(Op1
, m_OneUse(m_Shl(m_Value(B
), m_Specific(Cst1
))))) {
5883 unsigned TypeBits
= Cst1
->getBitWidth();
5884 unsigned ShAmt
= (unsigned)Cst1
->getLimitedValue(TypeBits
);
5885 if (ShAmt
< TypeBits
&& ShAmt
!= 0) {
5886 Value
*Xor
= Builder
.CreateXor(A
, B
, I
.getName() + ".unshifted");
5887 APInt AndVal
= APInt::getLowBitsSet(TypeBits
, TypeBits
- ShAmt
);
5888 Value
*And
= Builder
.CreateAnd(Xor
, Builder
.getInt(AndVal
),
5889 I
.getName() + ".mask");
5890 return new ICmpInst(Pred
, And
, Constant::getNullValue(Cst1
->getType()));
5894 // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
5895 // "icmp (and X, mask), cst"
5897 if (Op0
->hasOneUse() &&
5898 match(Op0
, m_Trunc(m_OneUse(m_LShr(m_Value(A
), m_ConstantInt(ShAmt
))))) &&
5899 match(Op1
, m_ConstantInt(Cst1
)) &&
5900 // Only do this when A has multiple uses. This is most important to do
5901 // when it exposes other optimizations.
5903 unsigned ASize
= cast
<IntegerType
>(A
->getType())->getPrimitiveSizeInBits();
5905 if (ShAmt
< ASize
) {
5907 APInt::getLowBitsSet(ASize
, Op0
->getType()->getPrimitiveSizeInBits());
5910 APInt CmpV
= Cst1
->getValue().zext(ASize
);
5913 Value
*Mask
= Builder
.CreateAnd(A
, Builder
.getInt(MaskV
));
5914 return new ICmpInst(Pred
, Mask
, Builder
.getInt(CmpV
));
5918 if (Instruction
*ICmp
= foldICmpIntrinsicWithIntrinsic(I
, Builder
))
5921 // Match icmp eq (trunc (lshr A, BW), (ashr (trunc A), BW-1)), which checks the
5922 // top BW/2 + 1 bits are all the same. Create "A >=s INT_MIN && A <=s INT_MAX",
5923 // which we generate as "icmp ult (add A, 2^(BW-1)), 2^BW" to skip a few steps
5925 unsigned BitWidth
= Op0
->getType()->getScalarSizeInBits();
5926 if (match(Op0
, m_AShr(m_Trunc(m_Value(A
)), m_SpecificInt(BitWidth
- 1))) &&
5927 match(Op1
, m_Trunc(m_LShr(m_Specific(A
), m_SpecificInt(BitWidth
)))) &&
5928 A
->getType()->getScalarSizeInBits() == BitWidth
* 2 &&
5929 (I
.getOperand(0)->hasOneUse() || I
.getOperand(1)->hasOneUse())) {
5930 APInt C
= APInt::getOneBitSet(BitWidth
* 2, BitWidth
- 1);
5931 Value
*Add
= Builder
.CreateAdd(A
, ConstantInt::get(A
->getType(), C
));
5932 return new ICmpInst(Pred
== ICmpInst::ICMP_EQ
? ICmpInst::ICMP_ULT
5933 : ICmpInst::ICMP_UGE
,
5934 Add
, ConstantInt::get(A
->getType(), C
.shl(1)));
5938 // Assume B_Pow2 != 0
5939 // 1. A & B_Pow2 != B_Pow2 -> A & B_Pow2 == 0
5940 // 2. A & B_Pow2 == B_Pow2 -> A & B_Pow2 != 0
5941 if (match(Op0
, m_c_And(m_Specific(Op1
), m_Value())) &&
5942 isKnownToBeAPowerOfTwo(Op1
, /* OrZero */ false, 0, &I
))
5943 return new ICmpInst(CmpInst::getInversePredicate(Pred
), Op0
,
5944 ConstantInt::getNullValue(Op0
->getType()));
5946 if (match(Op1
, m_c_And(m_Specific(Op0
), m_Value())) &&
5947 isKnownToBeAPowerOfTwo(Op0
, /* OrZero */ false, 0, &I
))
5948 return new ICmpInst(CmpInst::getInversePredicate(Pred
), Op1
,
5949 ConstantInt::getNullValue(Op1
->getType()));
5952 // icmp eq/ne X, OneUse(rotate-right(X))
5953 // -> icmp eq/ne X, rotate-left(X)
5954 // We generally try to convert rotate-right -> rotate-left, this just
5955 // canonicalizes another case.
5956 if (match(&I
, m_c_ICmp(m_Value(A
),
5957 m_OneUse(m_Intrinsic
<Intrinsic::fshr
>(
5958 m_Deferred(A
), m_Deferred(A
), m_Value(B
))))))
5959 return new ICmpInst(
5961 Builder
.CreateIntrinsic(Op0
->getType(), Intrinsic::fshl
, {A
, A
, B
}));
5964 // icmp eq/ne OneUse(A ^ Cst), B --> icmp eq/ne (A ^ B), Cst
5966 if (match(&I
, m_c_ICmp(m_OneUse(m_Xor(m_Value(A
), m_ImmConstant(Cst
))),
5967 m_CombineAnd(m_Value(B
), m_Unless(m_ImmConstant())))))
5968 return new ICmpInst(Pred
, Builder
.CreateXor(A
, B
), Cst
);
5971 // (icmp eq/ne (and (add/sub/xor X, P2), P2), P2)
5973 m_CombineOr(m_CombineOr(m_c_Add(m_Value(B
), m_Deferred(A
)),
5974 m_c_Xor(m_Value(B
), m_Deferred(A
))),
5975 m_Sub(m_Value(B
), m_Deferred(A
)));
5976 std::optional
<bool> IsZero
= std::nullopt
;
5977 if (match(&I
, m_c_ICmp(m_OneUse(m_c_And(m_Value(A
), m_Matcher
)),
5980 // (icmp eq/ne (and (add/sub/xor X, P2), P2), 0)
5982 m_ICmp(m_OneUse(m_c_And(m_Value(A
), m_Matcher
)), m_Zero())))
5985 if (IsZero
&& isKnownToBeAPowerOfTwo(A
, /* OrZero */ true, /*Depth*/ 0, &I
))
5986 // (icmp eq/ne (and (add/sub/xor X, P2), P2), P2)
5987 // -> (icmp eq/ne (and X, P2), 0)
5988 // (icmp eq/ne (and (add/sub/xor X, P2), P2), 0)
5989 // -> (icmp eq/ne (and X, P2), P2)
5990 return new ICmpInst(Pred
, Builder
.CreateAnd(B
, A
),
5992 : ConstantInt::getNullValue(A
->getType()));
5998 Instruction
*InstCombinerImpl::foldICmpWithTrunc(ICmpInst
&ICmp
) {
5999 ICmpInst::Predicate Pred
= ICmp
.getPredicate();
6000 Value
*Op0
= ICmp
.getOperand(0), *Op1
= ICmp
.getOperand(1);
6002 // Try to canonicalize trunc + compare-to-constant into a mask + cmp.
6003 // The trunc masks high bits while the compare may effectively mask low bits.
6006 if (!match(Op0
, m_OneUse(m_Trunc(m_Value(X
)))) || !match(Op1
, m_APInt(C
)))
6009 // This matches patterns corresponding to tests of the signbit as well as:
6010 // (trunc X) pred C2 --> (X & Mask) == C
6011 if (auto Res
= decomposeBitTestICmp(Op0
, Op1
, Pred
, /*WithTrunc=*/true,
6012 /*AllowNonZeroC=*/true)) {
6013 Value
*And
= Builder
.CreateAnd(Res
->X
, Res
->Mask
);
6014 Constant
*C
= ConstantInt::get(Res
->X
->getType(), Res
->C
);
6015 return new ICmpInst(Res
->Pred
, And
, C
);
6018 unsigned SrcBits
= X
->getType()->getScalarSizeInBits();
6019 if (auto *II
= dyn_cast
<IntrinsicInst
>(X
)) {
6020 if (II
->getIntrinsicID() == Intrinsic::cttz
||
6021 II
->getIntrinsicID() == Intrinsic::ctlz
) {
6022 unsigned MaxRet
= SrcBits
;
6023 // If the "is_zero_poison" argument is set, then we know at least
6024 // one bit is set in the input, so the result is always at least one
6025 // less than the full bitwidth of that input.
6026 if (match(II
->getArgOperand(1), m_One()))
6029 // Make sure the destination is wide enough to hold the largest output of
6031 if (llvm::Log2_32(MaxRet
) + 1 <= Op0
->getType()->getScalarSizeInBits())
6032 if (Instruction
*I
=
6033 foldICmpIntrinsicWithConstant(ICmp
, II
, C
->zext(SrcBits
)))
6041 Instruction
*InstCombinerImpl::foldICmpWithZextOrSext(ICmpInst
&ICmp
) {
6042 assert(isa
<CastInst
>(ICmp
.getOperand(0)) && "Expected cast for operand 0");
6043 auto *CastOp0
= cast
<CastInst
>(ICmp
.getOperand(0));
6045 if (!match(CastOp0
, m_ZExtOrSExt(m_Value(X
))))
6048 bool IsSignedExt
= CastOp0
->getOpcode() == Instruction::SExt
;
6049 bool IsSignedCmp
= ICmp
.isSigned();
6051 // icmp Pred (ext X), (ext Y)
6053 if (match(ICmp
.getOperand(1), m_ZExtOrSExt(m_Value(Y
)))) {
6054 bool IsZext0
= isa
<ZExtInst
>(ICmp
.getOperand(0));
6055 bool IsZext1
= isa
<ZExtInst
>(ICmp
.getOperand(1));
6057 if (IsZext0
!= IsZext1
) {
6058 // If X and Y and both i1
6059 // (icmp eq/ne (zext X) (sext Y))
6060 // eq -> (icmp eq (or X, Y), 0)
6061 // ne -> (icmp ne (or X, Y), 0)
6062 if (ICmp
.isEquality() && X
->getType()->isIntOrIntVectorTy(1) &&
6063 Y
->getType()->isIntOrIntVectorTy(1))
6064 return new ICmpInst(ICmp
.getPredicate(), Builder
.CreateOr(X
, Y
),
6065 Constant::getNullValue(X
->getType()));
6067 // If we have mismatched casts and zext has the nneg flag, we can
6068 // treat the "zext nneg" as "sext". Otherwise, we cannot fold and quit.
6070 auto *NonNegInst0
= dyn_cast
<PossiblyNonNegInst
>(ICmp
.getOperand(0));
6071 auto *NonNegInst1
= dyn_cast
<PossiblyNonNegInst
>(ICmp
.getOperand(1));
6073 bool IsNonNeg0
= NonNegInst0
&& NonNegInst0
->hasNonNeg();
6074 bool IsNonNeg1
= NonNegInst1
&& NonNegInst1
->hasNonNeg();
6076 if ((IsZext0
&& IsNonNeg0
) || (IsZext1
&& IsNonNeg1
))
6082 // Not an extension from the same type?
6083 Type
*XTy
= X
->getType(), *YTy
= Y
->getType();
6085 // One of the casts must have one use because we are creating a new cast.
6086 if (!ICmp
.getOperand(0)->hasOneUse() && !ICmp
.getOperand(1)->hasOneUse())
6088 // Extend the narrower operand to the type of the wider operand.
6089 CastInst::CastOps CastOpcode
=
6090 IsSignedExt
? Instruction::SExt
: Instruction::ZExt
;
6091 if (XTy
->getScalarSizeInBits() < YTy
->getScalarSizeInBits())
6092 X
= Builder
.CreateCast(CastOpcode
, X
, YTy
);
6093 else if (YTy
->getScalarSizeInBits() < XTy
->getScalarSizeInBits())
6094 Y
= Builder
.CreateCast(CastOpcode
, Y
, XTy
);
6099 // (zext X) == (zext Y) --> X == Y
6100 // (sext X) == (sext Y) --> X == Y
6101 if (ICmp
.isEquality())
6102 return new ICmpInst(ICmp
.getPredicate(), X
, Y
);
6104 // A signed comparison of sign extended values simplifies into a
6105 // signed comparison.
6106 if (IsSignedCmp
&& IsSignedExt
)
6107 return new ICmpInst(ICmp
.getPredicate(), X
, Y
);
6109 // The other three cases all fold into an unsigned comparison.
6110 return new ICmpInst(ICmp
.getUnsignedPredicate(), X
, Y
);
6113 // Below here, we are only folding a compare with constant.
6114 auto *C
= dyn_cast
<Constant
>(ICmp
.getOperand(1));
6118 // If a lossless truncate is possible...
6119 Type
*SrcTy
= CastOp0
->getSrcTy();
6120 Constant
*Res
= getLosslessTrunc(C
, SrcTy
, CastOp0
->getOpcode());
6122 if (ICmp
.isEquality())
6123 return new ICmpInst(ICmp
.getPredicate(), X
, Res
);
6125 // A signed comparison of sign extended values simplifies into a
6126 // signed comparison.
6127 if (IsSignedExt
&& IsSignedCmp
)
6128 return new ICmpInst(ICmp
.getPredicate(), X
, Res
);
6130 // The other three cases all fold into an unsigned comparison.
6131 return new ICmpInst(ICmp
.getUnsignedPredicate(), X
, Res
);
6134 // The re-extended constant changed, partly changed (in the case of a vector),
6135 // or could not be determined to be equal (in the case of a constant
6136 // expression), so the constant cannot be represented in the shorter type.
6137 // All the cases that fold to true or false will have already been handled
6138 // by simplifyICmpInst, so only deal with the tricky case.
6139 if (IsSignedCmp
|| !IsSignedExt
|| !isa
<ConstantInt
>(C
))
6142 // Is source op positive?
6143 // icmp ult (sext X), C --> icmp sgt X, -1
6144 if (ICmp
.getPredicate() == ICmpInst::ICMP_ULT
)
6145 return new ICmpInst(CmpInst::ICMP_SGT
, X
, Constant::getAllOnesValue(SrcTy
));
6147 // Is source op negative?
6148 // icmp ugt (sext X), C --> icmp slt X, 0
6149 assert(ICmp
.getPredicate() == ICmpInst::ICMP_UGT
&& "ICmp should be folded!");
6150 return new ICmpInst(CmpInst::ICMP_SLT
, X
, Constant::getNullValue(SrcTy
));
6153 /// Handle icmp (cast x), (cast or constant).
6154 Instruction
*InstCombinerImpl::foldICmpWithCastOp(ICmpInst
&ICmp
) {
6155 // If any operand of ICmp is a inttoptr roundtrip cast then remove it as
6156 // icmp compares only pointer's value.
6157 // icmp (inttoptr (ptrtoint p1)), p2 --> icmp p1, p2.
6158 Value
*SimplifiedOp0
= simplifyIntToPtrRoundTripCast(ICmp
.getOperand(0));
6159 Value
*SimplifiedOp1
= simplifyIntToPtrRoundTripCast(ICmp
.getOperand(1));
6160 if (SimplifiedOp0
|| SimplifiedOp1
)
6161 return new ICmpInst(ICmp
.getPredicate(),
6162 SimplifiedOp0
? SimplifiedOp0
: ICmp
.getOperand(0),
6163 SimplifiedOp1
? SimplifiedOp1
: ICmp
.getOperand(1));
6165 auto *CastOp0
= dyn_cast
<CastInst
>(ICmp
.getOperand(0));
6168 if (!isa
<Constant
>(ICmp
.getOperand(1)) && !isa
<CastInst
>(ICmp
.getOperand(1)))
6171 Value
*Op0Src
= CastOp0
->getOperand(0);
6172 Type
*SrcTy
= CastOp0
->getSrcTy();
6173 Type
*DestTy
= CastOp0
->getDestTy();
6175 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
6176 // integer type is the same size as the pointer type.
6177 auto CompatibleSizes
= [&](Type
*PtrTy
, Type
*IntTy
) {
6178 if (isa
<VectorType
>(PtrTy
)) {
6179 PtrTy
= cast
<VectorType
>(PtrTy
)->getElementType();
6180 IntTy
= cast
<VectorType
>(IntTy
)->getElementType();
6182 return DL
.getPointerTypeSizeInBits(PtrTy
) == IntTy
->getIntegerBitWidth();
6184 if (CastOp0
->getOpcode() == Instruction::PtrToInt
&&
6185 CompatibleSizes(SrcTy
, DestTy
)) {
6186 Value
*NewOp1
= nullptr;
6187 if (auto *PtrToIntOp1
= dyn_cast
<PtrToIntOperator
>(ICmp
.getOperand(1))) {
6188 Value
*PtrSrc
= PtrToIntOp1
->getOperand(0);
6189 if (PtrSrc
->getType() == Op0Src
->getType())
6190 NewOp1
= PtrToIntOp1
->getOperand(0);
6191 } else if (auto *RHSC
= dyn_cast
<Constant
>(ICmp
.getOperand(1))) {
6192 NewOp1
= ConstantExpr::getIntToPtr(RHSC
, SrcTy
);
6196 return new ICmpInst(ICmp
.getPredicate(), Op0Src
, NewOp1
);
6199 // Do the same in the other direction for icmp (inttoptr x), (inttoptr/c).
6200 if (CastOp0
->getOpcode() == Instruction::IntToPtr
&&
6201 CompatibleSizes(DestTy
, SrcTy
)) {
6202 Value
*NewOp1
= nullptr;
6203 if (auto *IntToPtrOp1
= dyn_cast
<IntToPtrInst
>(ICmp
.getOperand(1))) {
6204 Value
*IntSrc
= IntToPtrOp1
->getOperand(0);
6205 if (IntSrc
->getType() == Op0Src
->getType())
6206 NewOp1
= IntToPtrOp1
->getOperand(0);
6207 } else if (auto *RHSC
= dyn_cast
<Constant
>(ICmp
.getOperand(1))) {
6208 NewOp1
= ConstantFoldConstant(ConstantExpr::getPtrToInt(RHSC
, SrcTy
), DL
);
6212 return new ICmpInst(ICmp
.getPredicate(), Op0Src
, NewOp1
);
6215 if (Instruction
*R
= foldICmpWithTrunc(ICmp
))
6218 return foldICmpWithZextOrSext(ICmp
);
6221 static bool isNeutralValue(Instruction::BinaryOps BinaryOp
, Value
*RHS
, bool IsSigned
) {
6224 llvm_unreachable("Unsupported binary op");
6225 case Instruction::Add
:
6226 case Instruction::Sub
:
6227 return match(RHS
, m_Zero());
6228 case Instruction::Mul
:
6229 return !(RHS
->getType()->isIntOrIntVectorTy(1) && IsSigned
) &&
6230 match(RHS
, m_One());
6235 InstCombinerImpl::computeOverflow(Instruction::BinaryOps BinaryOp
,
6236 bool IsSigned
, Value
*LHS
, Value
*RHS
,
6237 Instruction
*CxtI
) const {
6240 llvm_unreachable("Unsupported binary op");
6241 case Instruction::Add
:
6243 return computeOverflowForSignedAdd(LHS
, RHS
, CxtI
);
6245 return computeOverflowForUnsignedAdd(LHS
, RHS
, CxtI
);
6246 case Instruction::Sub
:
6248 return computeOverflowForSignedSub(LHS
, RHS
, CxtI
);
6250 return computeOverflowForUnsignedSub(LHS
, RHS
, CxtI
);
6251 case Instruction::Mul
:
6253 return computeOverflowForSignedMul(LHS
, RHS
, CxtI
);
6255 return computeOverflowForUnsignedMul(LHS
, RHS
, CxtI
);
6259 bool InstCombinerImpl::OptimizeOverflowCheck(Instruction::BinaryOps BinaryOp
,
6260 bool IsSigned
, Value
*LHS
,
6261 Value
*RHS
, Instruction
&OrigI
,
6263 Constant
*&Overflow
) {
6264 if (OrigI
.isCommutative() && isa
<Constant
>(LHS
) && !isa
<Constant
>(RHS
))
6265 std::swap(LHS
, RHS
);
6267 // If the overflow check was an add followed by a compare, the insertion point
6268 // may be pointing to the compare. We want to insert the new instructions
6269 // before the add in case there are uses of the add between the add and the
6271 Builder
.SetInsertPoint(&OrigI
);
6273 Type
*OverflowTy
= Type::getInt1Ty(LHS
->getContext());
6274 if (auto *LHSTy
= dyn_cast
<VectorType
>(LHS
->getType()))
6275 OverflowTy
= VectorType::get(OverflowTy
, LHSTy
->getElementCount());
6277 if (isNeutralValue(BinaryOp
, RHS
, IsSigned
)) {
6279 Overflow
= ConstantInt::getFalse(OverflowTy
);
6283 switch (computeOverflow(BinaryOp
, IsSigned
, LHS
, RHS
, &OrigI
)) {
6284 case OverflowResult::MayOverflow
:
6286 case OverflowResult::AlwaysOverflowsLow
:
6287 case OverflowResult::AlwaysOverflowsHigh
:
6288 Result
= Builder
.CreateBinOp(BinaryOp
, LHS
, RHS
);
6289 Result
->takeName(&OrigI
);
6290 Overflow
= ConstantInt::getTrue(OverflowTy
);
6292 case OverflowResult::NeverOverflows
:
6293 Result
= Builder
.CreateBinOp(BinaryOp
, LHS
, RHS
);
6294 Result
->takeName(&OrigI
);
6295 Overflow
= ConstantInt::getFalse(OverflowTy
);
6296 if (auto *Inst
= dyn_cast
<Instruction
>(Result
)) {
6298 Inst
->setHasNoSignedWrap();
6300 Inst
->setHasNoUnsignedWrap();
6305 llvm_unreachable("Unexpected overflow result");
6308 /// Recognize and process idiom involving test for multiplication
6311 /// The caller has matched a pattern of the form:
6312 /// I = cmp u (mul(zext A, zext B), V
6313 /// The function checks if this is a test for overflow and if so replaces
6314 /// multiplication with call to 'mul.with.overflow' intrinsic.
6316 /// \param I Compare instruction.
6317 /// \param MulVal Result of 'mult' instruction. It is one of the arguments of
6318 /// the compare instruction. Must be of integer type.
6319 /// \param OtherVal The other argument of compare instruction.
6320 /// \returns Instruction which must replace the compare instruction, NULL if no
6321 /// replacement required.
6322 static Instruction
*processUMulZExtIdiom(ICmpInst
&I
, Value
*MulVal
,
6323 const APInt
*OtherVal
,
6324 InstCombinerImpl
&IC
) {
6325 // Don't bother doing this transformation for pointers, don't do it for
6327 if (!isa
<IntegerType
>(MulVal
->getType()))
6330 auto *MulInstr
= dyn_cast
<Instruction
>(MulVal
);
6333 assert(MulInstr
->getOpcode() == Instruction::Mul
);
6335 auto *LHS
= cast
<ZExtInst
>(MulInstr
->getOperand(0)),
6336 *RHS
= cast
<ZExtInst
>(MulInstr
->getOperand(1));
6337 assert(LHS
->getOpcode() == Instruction::ZExt
);
6338 assert(RHS
->getOpcode() == Instruction::ZExt
);
6339 Value
*A
= LHS
->getOperand(0), *B
= RHS
->getOperand(0);
6341 // Calculate type and width of the result produced by mul.with.overflow.
6342 Type
*TyA
= A
->getType(), *TyB
= B
->getType();
6343 unsigned WidthA
= TyA
->getPrimitiveSizeInBits(),
6344 WidthB
= TyB
->getPrimitiveSizeInBits();
6347 if (WidthB
> WidthA
) {
6355 // In order to replace the original mul with a narrower mul.with.overflow,
6356 // all uses must ignore upper bits of the product. The number of used low
6357 // bits must be not greater than the width of mul.with.overflow.
6358 if (MulVal
->hasNUsesOrMore(2))
6359 for (User
*U
: MulVal
->users()) {
6362 if (TruncInst
*TI
= dyn_cast
<TruncInst
>(U
)) {
6363 // Check if truncation ignores bits above MulWidth.
6364 unsigned TruncWidth
= TI
->getType()->getPrimitiveSizeInBits();
6365 if (TruncWidth
> MulWidth
)
6367 } else if (BinaryOperator
*BO
= dyn_cast
<BinaryOperator
>(U
)) {
6368 // Check if AND ignores bits above MulWidth.
6369 if (BO
->getOpcode() != Instruction::And
)
6371 if (ConstantInt
*CI
= dyn_cast
<ConstantInt
>(BO
->getOperand(1))) {
6372 const APInt
&CVal
= CI
->getValue();
6373 if (CVal
.getBitWidth() - CVal
.countl_zero() > MulWidth
)
6376 // In this case we could have the operand of the binary operation
6377 // being defined in another block, and performing the replacement
6378 // could break the dominance relation.
6382 // Other uses prohibit this transformation.
6387 // Recognize patterns
6388 switch (I
.getPredicate()) {
6389 case ICmpInst::ICMP_UGT
: {
6390 // Recognize pattern:
6391 // mulval = mul(zext A, zext B)
6392 // cmp ugt mulval, max
6393 APInt MaxVal
= APInt::getMaxValue(MulWidth
);
6394 MaxVal
= MaxVal
.zext(OtherVal
->getBitWidth());
6395 if (MaxVal
.eq(*OtherVal
))
6396 break; // Recognized
6400 case ICmpInst::ICMP_ULT
: {
6401 // Recognize pattern:
6402 // mulval = mul(zext A, zext B)
6403 // cmp ule mulval, max + 1
6404 APInt MaxVal
= APInt::getOneBitSet(OtherVal
->getBitWidth(), MulWidth
);
6405 if (MaxVal
.eq(*OtherVal
))
6406 break; // Recognized
6414 InstCombiner::BuilderTy
&Builder
= IC
.Builder
;
6415 Builder
.SetInsertPoint(MulInstr
);
6417 // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B)
6418 Value
*MulA
= A
, *MulB
= B
;
6419 if (WidthA
< MulWidth
)
6420 MulA
= Builder
.CreateZExt(A
, MulType
);
6421 if (WidthB
< MulWidth
)
6422 MulB
= Builder
.CreateZExt(B
, MulType
);
6424 Builder
.CreateIntrinsic(Intrinsic::umul_with_overflow
, MulType
,
6425 {MulA
, MulB
}, /*FMFSource=*/nullptr, "umul");
6426 IC
.addToWorklist(MulInstr
);
6428 // If there are uses of mul result other than the comparison, we know that
6429 // they are truncation or binary AND. Change them to use result of
6430 // mul.with.overflow and adjust properly mask/size.
6431 if (MulVal
->hasNUsesOrMore(2)) {
6432 Value
*Mul
= Builder
.CreateExtractValue(Call
, 0, "umul.value");
6433 for (User
*U
: make_early_inc_range(MulVal
->users())) {
6436 if (TruncInst
*TI
= dyn_cast
<TruncInst
>(U
)) {
6437 if (TI
->getType()->getPrimitiveSizeInBits() == MulWidth
)
6438 IC
.replaceInstUsesWith(*TI
, Mul
);
6440 TI
->setOperand(0, Mul
);
6441 } else if (BinaryOperator
*BO
= dyn_cast
<BinaryOperator
>(U
)) {
6442 assert(BO
->getOpcode() == Instruction::And
);
6443 // Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
6444 ConstantInt
*CI
= cast
<ConstantInt
>(BO
->getOperand(1));
6445 APInt ShortMask
= CI
->getValue().trunc(MulWidth
);
6446 Value
*ShortAnd
= Builder
.CreateAnd(Mul
, ShortMask
);
6447 Value
*Zext
= Builder
.CreateZExt(ShortAnd
, BO
->getType());
6448 IC
.replaceInstUsesWith(*BO
, Zext
);
6450 llvm_unreachable("Unexpected Binary operation");
6452 IC
.addToWorklist(cast
<Instruction
>(U
));
6456 // The original icmp gets replaced with the overflow value, maybe inverted
6457 // depending on predicate.
6458 if (I
.getPredicate() == ICmpInst::ICMP_ULT
) {
6459 Value
*Res
= Builder
.CreateExtractValue(Call
, 1);
6460 return BinaryOperator::CreateNot(Res
);
6463 return ExtractValueInst::Create(Call
, 1);
6466 /// When performing a comparison against a constant, it is possible that not all
6467 /// the bits in the LHS are demanded. This helper method computes the mask that
6469 static APInt
getDemandedBitsLHSMask(ICmpInst
&I
, unsigned BitWidth
) {
6471 if (!match(I
.getOperand(1), m_APInt(RHS
)))
6472 return APInt::getAllOnes(BitWidth
);
6474 // If this is a normal comparison, it demands all bits. If it is a sign bit
6475 // comparison, it only demands the sign bit.
6477 if (isSignBitCheck(I
.getPredicate(), *RHS
, UnusedBit
))
6478 return APInt::getSignMask(BitWidth
);
6480 switch (I
.getPredicate()) {
6481 // For a UGT comparison, we don't care about any bits that
6482 // correspond to the trailing ones of the comparand. The value of these
6483 // bits doesn't impact the outcome of the comparison, because any value
6484 // greater than the RHS must differ in a bit higher than these due to carry.
6485 case ICmpInst::ICMP_UGT
:
6486 return APInt::getBitsSetFrom(BitWidth
, RHS
->countr_one());
6488 // Similarly, for a ULT comparison, we don't care about the trailing zeros.
6489 // Any value less than the RHS must differ in a higher bit because of carries.
6490 case ICmpInst::ICMP_ULT
:
6491 return APInt::getBitsSetFrom(BitWidth
, RHS
->countr_zero());
6494 return APInt::getAllOnes(BitWidth
);
6498 /// Check that one use is in the same block as the definition and all
6499 /// other uses are in blocks dominated by a given block.
6501 /// \param DI Definition
6503 /// \param DB Block that must dominate all uses of \p DI outside
6504 /// the parent block
6505 /// \return true when \p UI is the only use of \p DI in the parent block
6506 /// and all other uses of \p DI are in blocks dominated by \p DB.
6508 bool InstCombinerImpl::dominatesAllUses(const Instruction
*DI
,
6509 const Instruction
*UI
,
6510 const BasicBlock
*DB
) const {
6511 assert(DI
&& UI
&& "Instruction not defined\n");
6512 // Ignore incomplete definitions.
6513 if (!DI
->getParent())
6515 // DI and UI must be in the same block.
6516 if (DI
->getParent() != UI
->getParent())
6518 // Protect from self-referencing blocks.
6519 if (DI
->getParent() == DB
)
6521 for (const User
*U
: DI
->users()) {
6522 auto *Usr
= cast
<Instruction
>(U
);
6523 if (Usr
!= UI
&& !DT
.dominates(DB
, Usr
->getParent()))
6529 /// Return true when the instruction sequence within a block is select-cmp-br.
6530 static bool isChainSelectCmpBranch(const SelectInst
*SI
) {
6531 const BasicBlock
*BB
= SI
->getParent();
6534 auto *BI
= dyn_cast_or_null
<BranchInst
>(BB
->getTerminator());
6535 if (!BI
|| BI
->getNumSuccessors() != 2)
6537 auto *IC
= dyn_cast
<ICmpInst
>(BI
->getCondition());
6538 if (!IC
|| (IC
->getOperand(0) != SI
&& IC
->getOperand(1) != SI
))
6543 /// True when a select result is replaced by one of its operands
6544 /// in select-icmp sequence. This will eventually result in the elimination
6547 /// \param SI Select instruction
6548 /// \param Icmp Compare instruction
6549 /// \param SIOpd Operand that replaces the select
6552 /// - The replacement is global and requires dominator information
6553 /// - The caller is responsible for the actual replacement
6558 /// %4 = select i1 %3, %C* %0, %C* null
6559 /// %5 = icmp eq %C* %4, null
6560 /// br i1 %5, label %9, label %7
6562 /// ; <label>:7 ; preds = %entry
6563 /// %8 = getelementptr inbounds %C* %4, i64 0, i32 0
6566 /// can be transformed to
6568 /// %5 = icmp eq %C* %0, null
6569 /// %6 = select i1 %3, i1 %5, i1 true
6570 /// br i1 %6, label %9, label %7
6572 /// ; <label>:7 ; preds = %entry
6573 /// %8 = getelementptr inbounds %C* %0, i64 0, i32 0 // replace by %0!
6575 /// Similar when the first operand of the select is a constant or/and
6576 /// the compare is for not equal rather than equal.
6578 /// NOTE: The function is only called when the select and compare constants
6579 /// are equal, the optimization can work only for EQ predicates. This is not a
6580 /// major restriction since a NE compare should be 'normalized' to an equal
6581 /// compare, which usually happens in the combiner and test case
6582 /// select-cmp-br.ll checks for it.
6583 bool InstCombinerImpl::replacedSelectWithOperand(SelectInst
*SI
,
6584 const ICmpInst
*Icmp
,
6585 const unsigned SIOpd
) {
6586 assert((SIOpd
== 1 || SIOpd
== 2) && "Invalid select operand!");
6587 if (isChainSelectCmpBranch(SI
) && Icmp
->getPredicate() == ICmpInst::ICMP_EQ
) {
6588 BasicBlock
*Succ
= SI
->getParent()->getTerminator()->getSuccessor(1);
6589 // The check for the single predecessor is not the best that can be
6590 // done. But it protects efficiently against cases like when SI's
6591 // home block has two successors, Succ and Succ1, and Succ1 predecessor
6592 // of Succ. Then SI can't be replaced by SIOpd because the use that gets
6593 // replaced can be reached on either path. So the uniqueness check
6594 // guarantees that the path all uses of SI (outside SI's parent) are on
6595 // is disjoint from all other paths out of SI. But that information
6596 // is more expensive to compute, and the trade-off here is in favor
6597 // of compile-time. It should also be noticed that we check for a single
6598 // predecessor and not only uniqueness. This to handle the situation when
6599 // Succ and Succ1 points to the same basic block.
6600 if (Succ
->getSinglePredecessor() && dominatesAllUses(SI
, Icmp
, Succ
)) {
6602 SI
->replaceUsesOutsideBlock(SI
->getOperand(SIOpd
), SI
->getParent());
6609 /// Try to fold the comparison based on range information we can get by checking
6610 /// whether bits are known to be zero or one in the inputs.
6611 Instruction
*InstCombinerImpl::foldICmpUsingKnownBits(ICmpInst
&I
) {
6612 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
6613 Type
*Ty
= Op0
->getType();
6614 ICmpInst::Predicate Pred
= I
.getPredicate();
6616 // Get scalar or pointer size.
6617 unsigned BitWidth
= Ty
->isIntOrIntVectorTy()
6618 ? Ty
->getScalarSizeInBits()
6619 : DL
.getPointerTypeSizeInBits(Ty
->getScalarType());
6624 KnownBits
Op0Known(BitWidth
);
6625 KnownBits
Op1Known(BitWidth
);
6628 // Don't use dominating conditions when folding icmp using known bits. This
6629 // may convert signed into unsigned predicates in ways that other passes
6630 // (especially IndVarSimplify) may not be able to reliably undo.
6631 SimplifyQuery Q
= SQ
.getWithoutDomCondCache().getWithInstruction(&I
);
6632 if (SimplifyDemandedBits(&I
, 0, getDemandedBitsLHSMask(I
, BitWidth
),
6633 Op0Known
, /*Depth=*/0, Q
))
6636 if (SimplifyDemandedBits(&I
, 1, APInt::getAllOnes(BitWidth
), Op1Known
,
6641 if (!isa
<Constant
>(Op0
) && Op0Known
.isConstant())
6642 return new ICmpInst(
6643 Pred
, ConstantExpr::getIntegerValue(Ty
, Op0Known
.getConstant()), Op1
);
6644 if (!isa
<Constant
>(Op1
) && Op1Known
.isConstant())
6645 return new ICmpInst(
6646 Pred
, Op0
, ConstantExpr::getIntegerValue(Ty
, Op1Known
.getConstant()));
6648 if (std::optional
<bool> Res
= ICmpInst::compare(Op0Known
, Op1Known
, Pred
))
6649 return replaceInstUsesWith(I
, ConstantInt::getBool(I
.getType(), *Res
));
6651 // Given the known and unknown bits, compute a range that the LHS could be
6652 // in. Compute the Min, Max and RHS values based on the known bits. For the
6653 // EQ and NE we use unsigned values.
6654 APInt
Op0Min(BitWidth
, 0), Op0Max(BitWidth
, 0);
6655 APInt
Op1Min(BitWidth
, 0), Op1Max(BitWidth
, 0);
6657 Op0Min
= Op0Known
.getSignedMinValue();
6658 Op0Max
= Op0Known
.getSignedMaxValue();
6659 Op1Min
= Op1Known
.getSignedMinValue();
6660 Op1Max
= Op1Known
.getSignedMaxValue();
6662 Op0Min
= Op0Known
.getMinValue();
6663 Op0Max
= Op0Known
.getMaxValue();
6664 Op1Min
= Op1Known
.getMinValue();
6665 Op1Max
= Op1Known
.getMaxValue();
6668 // Don't break up a clamp pattern -- (min(max X, Y), Z) -- by replacing a
6669 // min/max canonical compare with some other compare. That could lead to
6670 // conflict with select canonicalization and infinite looping.
6671 // FIXME: This constraint may go away if min/max intrinsics are canonical.
6672 auto isMinMaxCmp
= [&](Instruction
&Cmp
) {
6673 if (!Cmp
.hasOneUse())
6676 SelectPatternFlavor SPF
= matchSelectPattern(Cmp
.user_back(), A
, B
).Flavor
;
6677 if (!SelectPatternResult::isMinOrMax(SPF
))
6679 return match(Op0
, m_MaxOrMin(m_Value(), m_Value())) ||
6680 match(Op1
, m_MaxOrMin(m_Value(), m_Value()));
6682 if (!isMinMaxCmp(I
)) {
6686 case ICmpInst::ICMP_ULT
: {
6687 if (Op1Min
== Op0Max
) // A <u B -> A != B if max(A) == min(B)
6688 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
, Op1
);
6690 if (match(Op1
, m_APInt(CmpC
))) {
6691 // A <u C -> A == C-1 if min(A)+1 == C
6692 if (*CmpC
== Op0Min
+ 1)
6693 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
,
6694 ConstantInt::get(Op1
->getType(), *CmpC
- 1));
6695 // X <u C --> X == 0, if the number of zero bits in the bottom of X
6696 // exceeds the log2 of C.
6697 if (Op0Known
.countMinTrailingZeros() >= CmpC
->ceilLogBase2())
6698 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
,
6699 Constant::getNullValue(Op1
->getType()));
6703 case ICmpInst::ICMP_UGT
: {
6704 if (Op1Max
== Op0Min
) // A >u B -> A != B if min(A) == max(B)
6705 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
, Op1
);
6707 if (match(Op1
, m_APInt(CmpC
))) {
6708 // A >u C -> A == C+1 if max(a)-1 == C
6709 if (*CmpC
== Op0Max
- 1)
6710 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
,
6711 ConstantInt::get(Op1
->getType(), *CmpC
+ 1));
6712 // X >u C --> X != 0, if the number of zero bits in the bottom of X
6713 // exceeds the log2 of C.
6714 if (Op0Known
.countMinTrailingZeros() >= CmpC
->getActiveBits())
6715 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
,
6716 Constant::getNullValue(Op1
->getType()));
6720 case ICmpInst::ICMP_SLT
: {
6721 if (Op1Min
== Op0Max
) // A <s B -> A != B if max(A) == min(B)
6722 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
, Op1
);
6724 if (match(Op1
, m_APInt(CmpC
))) {
6725 if (*CmpC
== Op0Min
+ 1) // A <s C -> A == C-1 if min(A)+1 == C
6726 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
,
6727 ConstantInt::get(Op1
->getType(), *CmpC
- 1));
6731 case ICmpInst::ICMP_SGT
: {
6732 if (Op1Max
== Op0Min
) // A >s B -> A != B if min(A) == max(B)
6733 return new ICmpInst(ICmpInst::ICMP_NE
, Op0
, Op1
);
6735 if (match(Op1
, m_APInt(CmpC
))) {
6736 if (*CmpC
== Op0Max
- 1) // A >s C -> A == C+1 if max(A)-1 == C
6737 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
,
6738 ConstantInt::get(Op1
->getType(), *CmpC
+ 1));
6745 // Based on the range information we know about the LHS, see if we can
6746 // simplify this comparison. For example, (x&4) < 8 is always true.
6750 case ICmpInst::ICMP_EQ
:
6751 case ICmpInst::ICMP_NE
: {
6752 // If all bits are known zero except for one, then we know at most one bit
6753 // is set. If the comparison is against zero, then this is a check to see if
6754 // *that* bit is set.
6755 APInt Op0KnownZeroInverted
= ~Op0Known
.Zero
;
6756 if (Op1Known
.isZero()) {
6757 // If the LHS is an AND with the same constant, look through it.
6758 Value
*LHS
= nullptr;
6760 if (!match(Op0
, m_And(m_Value(LHS
), m_APInt(LHSC
))) ||
6761 *LHSC
!= Op0KnownZeroInverted
)
6766 if (match(LHS
, m_Shl(m_Power2(C1
), m_Value(X
)))) {
6767 Type
*XTy
= X
->getType();
6768 unsigned Log2C1
= C1
->countr_zero();
6769 APInt C2
= Op0KnownZeroInverted
;
6770 APInt C2Pow2
= (C2
& ~(*C1
- 1)) + *C1
;
6771 if (C2Pow2
.isPowerOf2()) {
6772 // iff (C1 is pow2) & ((C2 & ~(C1-1)) + C1) is pow2):
6773 // ((C1 << X) & C2) == 0 -> X >= (Log2(C2+C1) - Log2(C1))
6774 // ((C1 << X) & C2) != 0 -> X < (Log2(C2+C1) - Log2(C1))
6775 unsigned Log2C2
= C2Pow2
.countr_zero();
6776 auto *CmpC
= ConstantInt::get(XTy
, Log2C2
- Log2C1
);
6778 Pred
== CmpInst::ICMP_EQ
? CmpInst::ICMP_UGE
: CmpInst::ICMP_ULT
;
6779 return new ICmpInst(NewPred
, X
, CmpC
);
6784 // Op0 eq C_Pow2 -> Op0 ne 0 if Op0 is known to be C_Pow2 or zero.
6785 if (Op1Known
.isConstant() && Op1Known
.getConstant().isPowerOf2() &&
6786 (Op0Known
& Op1Known
) == Op0Known
)
6787 return new ICmpInst(CmpInst::getInversePredicate(Pred
), Op0
,
6788 ConstantInt::getNullValue(Op1
->getType()));
6791 case ICmpInst::ICMP_SGE
:
6792 if (Op1Min
== Op0Max
) // A >=s B -> A == B if max(A) == min(B)
6793 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
, Op1
);
6795 case ICmpInst::ICMP_SLE
:
6796 if (Op1Max
== Op0Min
) // A <=s B -> A == B if min(A) == max(B)
6797 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
, Op1
);
6799 case ICmpInst::ICMP_UGE
:
6800 if (Op1Min
== Op0Max
) // A >=u B -> A == B if max(A) == min(B)
6801 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
, Op1
);
6803 case ICmpInst::ICMP_ULE
:
6804 if (Op1Max
== Op0Min
) // A <=u B -> A == B if min(A) == max(B)
6805 return new ICmpInst(ICmpInst::ICMP_EQ
, Op0
, Op1
);
6809 // Turn a signed comparison into an unsigned one if both operands are known to
6810 // have the same sign. Set samesign if possible (except for equality
6812 if ((I
.isSigned() || (I
.isUnsigned() && !I
.hasSameSign())) &&
6813 ((Op0Known
.Zero
.isNegative() && Op1Known
.Zero
.isNegative()) ||
6814 (Op0Known
.One
.isNegative() && Op1Known
.One
.isNegative()))) {
6815 I
.setPredicate(I
.getUnsignedPredicate());
6823 /// If one operand of an icmp is effectively a bool (value range of {0,1}),
6824 /// then try to reduce patterns based on that limit.
6825 Instruction
*InstCombinerImpl::foldICmpUsingBoolRange(ICmpInst
&I
) {
6829 // X must be 0 and bool must be true for "ULT":
6830 // X <u (zext i1 Y) --> (X == 0) & Y
6831 if (match(&I
, m_c_ICmp(Pred
, m_Value(X
), m_OneUse(m_ZExt(m_Value(Y
))))) &&
6832 Y
->getType()->isIntOrIntVectorTy(1) && Pred
== ICmpInst::ICMP_ULT
)
6833 return BinaryOperator::CreateAnd(Builder
.CreateIsNull(X
), Y
);
6835 // X must be 0 or bool must be true for "ULE":
6836 // X <=u (sext i1 Y) --> (X == 0) | Y
6837 if (match(&I
, m_c_ICmp(Pred
, m_Value(X
), m_OneUse(m_SExt(m_Value(Y
))))) &&
6838 Y
->getType()->isIntOrIntVectorTy(1) && Pred
== ICmpInst::ICMP_ULE
)
6839 return BinaryOperator::CreateOr(Builder
.CreateIsNull(X
), Y
);
6841 // icmp eq/ne X, (zext/sext (icmp eq/ne X, C))
6842 CmpPredicate Pred1
, Pred2
;
6845 if (match(&I
, m_c_ICmp(Pred1
, m_Value(X
),
6846 m_CombineAnd(m_Instruction(ExtI
),
6847 m_ZExtOrSExt(m_ICmp(Pred2
, m_Deferred(X
),
6849 ICmpInst::isEquality(Pred1
) && ICmpInst::isEquality(Pred2
)) {
6850 bool IsSExt
= ExtI
->getOpcode() == Instruction::SExt
;
6851 bool HasOneUse
= ExtI
->hasOneUse() && ExtI
->getOperand(0)->hasOneUse();
6852 auto CreateRangeCheck
= [&] {
6854 Builder
.CreateICmp(Pred1
, X
, Constant::getNullValue(X
->getType()));
6855 Value
*CmpV2
= Builder
.CreateICmp(
6856 Pred1
, X
, ConstantInt::getSigned(X
->getType(), IsSExt
? -1 : 1));
6857 return BinaryOperator::Create(
6858 Pred1
== ICmpInst::ICMP_EQ
? Instruction::Or
: Instruction::And
,
6862 if (Pred2
== ICmpInst::ICMP_EQ
) {
6863 // icmp eq X, (zext/sext (icmp eq X, 0)) --> false
6864 // icmp ne X, (zext/sext (icmp eq X, 0)) --> true
6865 return replaceInstUsesWith(
6866 I
, ConstantInt::getBool(I
.getType(), Pred1
== ICmpInst::ICMP_NE
));
6867 } else if (!IsSExt
|| HasOneUse
) {
6868 // icmp eq X, (zext (icmp ne X, 0)) --> X == 0 || X == 1
6869 // icmp ne X, (zext (icmp ne X, 0)) --> X != 0 && X != 1
6870 // icmp eq X, (sext (icmp ne X, 0)) --> X == 0 || X == -1
6871 // icmp ne X, (sext (icmp ne X, 0)) --> X != 0 && X == -1
6872 return CreateRangeCheck();
6874 } else if (IsSExt
? C
->isAllOnes() : C
->isOne()) {
6875 if (Pred2
== ICmpInst::ICMP_NE
) {
6876 // icmp eq X, (zext (icmp ne X, 1)) --> false
6877 // icmp ne X, (zext (icmp ne X, 1)) --> true
6878 // icmp eq X, (sext (icmp ne X, -1)) --> false
6879 // icmp ne X, (sext (icmp ne X, -1)) --> true
6880 return replaceInstUsesWith(
6881 I
, ConstantInt::getBool(I
.getType(), Pred1
== ICmpInst::ICMP_NE
));
6882 } else if (!IsSExt
|| HasOneUse
) {
6883 // icmp eq X, (zext (icmp eq X, 1)) --> X == 0 || X == 1
6884 // icmp ne X, (zext (icmp eq X, 1)) --> X != 0 && X != 1
6885 // icmp eq X, (sext (icmp eq X, -1)) --> X == 0 || X == -1
6886 // icmp ne X, (sext (icmp eq X, -1)) --> X != 0 && X == -1
6887 return CreateRangeCheck();
6890 // when C != 0 && C != 1:
6891 // icmp eq X, (zext (icmp eq X, C)) --> icmp eq X, 0
6892 // icmp eq X, (zext (icmp ne X, C)) --> icmp eq X, 1
6893 // icmp ne X, (zext (icmp eq X, C)) --> icmp ne X, 0
6894 // icmp ne X, (zext (icmp ne X, C)) --> icmp ne X, 1
6895 // when C != 0 && C != -1:
6896 // icmp eq X, (sext (icmp eq X, C)) --> icmp eq X, 0
6897 // icmp eq X, (sext (icmp ne X, C)) --> icmp eq X, -1
6898 // icmp ne X, (sext (icmp eq X, C)) --> icmp ne X, 0
6899 // icmp ne X, (sext (icmp ne X, C)) --> icmp ne X, -1
6900 return ICmpInst::Create(
6901 Instruction::ICmp
, Pred1
, X
,
6902 ConstantInt::getSigned(X
->getType(), Pred2
== ICmpInst::ICMP_NE
6911 std::optional
<std::pair
<CmpPredicate
, Constant
*>>
6912 InstCombiner::getFlippedStrictnessPredicateAndConstant(CmpPredicate Pred
,
6914 assert(ICmpInst::isRelational(Pred
) && ICmpInst::isIntPredicate(Pred
) &&
6915 "Only for relational integer predicates.");
6917 Type
*Type
= C
->getType();
6918 bool IsSigned
= ICmpInst::isSigned(Pred
);
6920 CmpInst::Predicate UnsignedPred
= ICmpInst::getUnsignedPredicate(Pred
);
6921 bool WillIncrement
=
6922 UnsignedPred
== ICmpInst::ICMP_ULE
|| UnsignedPred
== ICmpInst::ICMP_UGT
;
6924 // Check if the constant operand can be safely incremented/decremented
6925 // without overflowing/underflowing.
6926 auto ConstantIsOk
= [WillIncrement
, IsSigned
](ConstantInt
*C
) {
6927 return WillIncrement
? !C
->isMaxValue(IsSigned
) : !C
->isMinValue(IsSigned
);
6930 Constant
*SafeReplacementConstant
= nullptr;
6931 if (auto *CI
= dyn_cast
<ConstantInt
>(C
)) {
6932 // Bail out if the constant can't be safely incremented/decremented.
6933 if (!ConstantIsOk(CI
))
6934 return std::nullopt
;
6935 } else if (auto *FVTy
= dyn_cast
<FixedVectorType
>(Type
)) {
6936 unsigned NumElts
= FVTy
->getNumElements();
6937 for (unsigned i
= 0; i
!= NumElts
; ++i
) {
6938 Constant
*Elt
= C
->getAggregateElement(i
);
6940 return std::nullopt
;
6942 if (isa
<UndefValue
>(Elt
))
6945 // Bail out if we can't determine if this constant is min/max or if we
6946 // know that this constant is min/max.
6947 auto *CI
= dyn_cast
<ConstantInt
>(Elt
);
6948 if (!CI
|| !ConstantIsOk(CI
))
6949 return std::nullopt
;
6951 if (!SafeReplacementConstant
)
6952 SafeReplacementConstant
= CI
;
6954 } else if (isa
<VectorType
>(C
->getType())) {
6955 // Handle scalable splat
6956 Value
*SplatC
= C
->getSplatValue();
6957 auto *CI
= dyn_cast_or_null
<ConstantInt
>(SplatC
);
6958 // Bail out if the constant can't be safely incremented/decremented.
6959 if (!CI
|| !ConstantIsOk(CI
))
6960 return std::nullopt
;
6963 return std::nullopt
;
6966 // It may not be safe to change a compare predicate in the presence of
6967 // undefined elements, so replace those elements with the first safe constant
6969 // TODO: in case of poison, it is safe; let's replace undefs only.
6970 if (C
->containsUndefOrPoisonElement()) {
6971 assert(SafeReplacementConstant
&& "Replacement constant not set");
6972 C
= Constant::replaceUndefsWith(C
, SafeReplacementConstant
);
6975 CmpInst::Predicate NewPred
= CmpInst::getFlippedStrictnessPredicate(Pred
);
6977 // Increment or decrement the constant.
6978 Constant
*OneOrNegOne
= ConstantInt::get(Type
, WillIncrement
? 1 : -1, true);
6979 Constant
*NewC
= ConstantExpr::getAdd(C
, OneOrNegOne
);
6981 return std::make_pair(NewPred
, NewC
);
6984 /// If we have an icmp le or icmp ge instruction with a constant operand, turn
6985 /// it into the appropriate icmp lt or icmp gt instruction. This transform
6986 /// allows them to be folded in visitICmpInst.
6987 static ICmpInst
*canonicalizeCmpWithConstant(ICmpInst
&I
) {
6988 ICmpInst::Predicate Pred
= I
.getPredicate();
6989 if (ICmpInst::isEquality(Pred
) || !ICmpInst::isIntPredicate(Pred
) ||
6990 InstCombiner::isCanonicalPredicate(Pred
))
6993 Value
*Op0
= I
.getOperand(0);
6994 Value
*Op1
= I
.getOperand(1);
6995 auto *Op1C
= dyn_cast
<Constant
>(Op1
);
6999 auto FlippedStrictness
=
7000 InstCombiner::getFlippedStrictnessPredicateAndConstant(Pred
, Op1C
);
7001 if (!FlippedStrictness
)
7004 return new ICmpInst(FlippedStrictness
->first
, Op0
, FlippedStrictness
->second
);
7007 /// If we have a comparison with a non-canonical predicate, if we can update
7008 /// all the users, invert the predicate and adjust all the users.
7009 CmpInst
*InstCombinerImpl::canonicalizeICmpPredicate(CmpInst
&I
) {
7010 // Is the predicate already canonical?
7011 CmpInst::Predicate Pred
= I
.getPredicate();
7012 if (InstCombiner::isCanonicalPredicate(Pred
))
7015 // Can all users be adjusted to predicate inversion?
7016 if (!InstCombiner::canFreelyInvertAllUsersOf(&I
, /*IgnoredUser=*/nullptr))
7019 // Ok, we can canonicalize comparison!
7020 // Let's first invert the comparison's predicate.
7021 I
.setPredicate(CmpInst::getInversePredicate(Pred
));
7022 I
.setName(I
.getName() + ".not");
7024 // And, adapt users.
7025 freelyInvertAllUsersOf(&I
);
7030 /// Integer compare with boolean values can always be turned into bitwise ops.
7031 static Instruction
*canonicalizeICmpBool(ICmpInst
&I
,
7032 InstCombiner::BuilderTy
&Builder
) {
7033 Value
*A
= I
.getOperand(0), *B
= I
.getOperand(1);
7034 assert(A
->getType()->isIntOrIntVectorTy(1) && "Bools only");
7036 // A boolean compared to true/false can be simplified to Op0/true/false in
7037 // 14 out of the 20 (10 predicates * 2 constants) possible combinations.
7038 // Cases not handled by InstSimplify are always 'not' of Op0.
7039 if (match(B
, m_Zero())) {
7040 switch (I
.getPredicate()) {
7041 case CmpInst::ICMP_EQ
: // A == 0 -> !A
7042 case CmpInst::ICMP_ULE
: // A <=u 0 -> !A
7043 case CmpInst::ICMP_SGE
: // A >=s 0 -> !A
7044 return BinaryOperator::CreateNot(A
);
7046 llvm_unreachable("ICmp i1 X, C not simplified as expected.");
7048 } else if (match(B
, m_One())) {
7049 switch (I
.getPredicate()) {
7050 case CmpInst::ICMP_NE
: // A != 1 -> !A
7051 case CmpInst::ICMP_ULT
: // A <u 1 -> !A
7052 case CmpInst::ICMP_SGT
: // A >s -1 -> !A
7053 return BinaryOperator::CreateNot(A
);
7055 llvm_unreachable("ICmp i1 X, C not simplified as expected.");
7059 switch (I
.getPredicate()) {
7061 llvm_unreachable("Invalid icmp instruction!");
7062 case ICmpInst::ICMP_EQ
:
7063 // icmp eq i1 A, B -> ~(A ^ B)
7064 return BinaryOperator::CreateNot(Builder
.CreateXor(A
, B
));
7066 case ICmpInst::ICMP_NE
:
7067 // icmp ne i1 A, B -> A ^ B
7068 return BinaryOperator::CreateXor(A
, B
);
7070 case ICmpInst::ICMP_UGT
:
7071 // icmp ugt -> icmp ult
7074 case ICmpInst::ICMP_ULT
:
7075 // icmp ult i1 A, B -> ~A & B
7076 return BinaryOperator::CreateAnd(Builder
.CreateNot(A
), B
);
7078 case ICmpInst::ICMP_SGT
:
7079 // icmp sgt -> icmp slt
7082 case ICmpInst::ICMP_SLT
:
7083 // icmp slt i1 A, B -> A & ~B
7084 return BinaryOperator::CreateAnd(Builder
.CreateNot(B
), A
);
7086 case ICmpInst::ICMP_UGE
:
7087 // icmp uge -> icmp ule
7090 case ICmpInst::ICMP_ULE
:
7091 // icmp ule i1 A, B -> ~A | B
7092 return BinaryOperator::CreateOr(Builder
.CreateNot(A
), B
);
7094 case ICmpInst::ICMP_SGE
:
7095 // icmp sge -> icmp sle
7098 case ICmpInst::ICMP_SLE
:
7099 // icmp sle i1 A, B -> A | ~B
7100 return BinaryOperator::CreateOr(Builder
.CreateNot(B
), A
);
7104 // Transform pattern like:
7105 // (1 << Y) u<= X or ~(-1 << Y) u< X or ((1 << Y)+(-1)) u< X
7106 // (1 << Y) u> X or ~(-1 << Y) u>= X or ((1 << Y)+(-1)) u>= X
7110 static Instruction
*foldICmpWithHighBitMask(ICmpInst
&Cmp
,
7111 InstCombiner::BuilderTy
&Builder
) {
7112 CmpPredicate Pred
, NewPred
;
7115 m_c_ICmp(Pred
, m_OneUse(m_Shl(m_One(), m_Value(Y
))), m_Value(X
)))) {
7117 case ICmpInst::ICMP_ULE
:
7118 NewPred
= ICmpInst::ICMP_NE
;
7120 case ICmpInst::ICMP_UGT
:
7121 NewPred
= ICmpInst::ICMP_EQ
;
7126 } else if (match(&Cmp
, m_c_ICmp(Pred
,
7127 m_OneUse(m_CombineOr(
7128 m_Not(m_Shl(m_AllOnes(), m_Value(Y
))),
7129 m_Add(m_Shl(m_One(), m_Value(Y
)),
7132 // The variant with 'add' is not canonical, (the variant with 'not' is)
7133 // we only get it because it has extra uses, and can't be canonicalized,
7136 case ICmpInst::ICMP_ULT
:
7137 NewPred
= ICmpInst::ICMP_NE
;
7139 case ICmpInst::ICMP_UGE
:
7140 NewPred
= ICmpInst::ICMP_EQ
;
7148 Value
*NewX
= Builder
.CreateLShr(X
, Y
, X
->getName() + ".highbits");
7149 Constant
*Zero
= Constant::getNullValue(NewX
->getType());
7150 return CmpInst::Create(Instruction::ICmp
, NewPred
, NewX
, Zero
);
7153 static Instruction
*foldVectorCmp(CmpInst
&Cmp
,
7154 InstCombiner::BuilderTy
&Builder
) {
7155 const CmpInst::Predicate Pred
= Cmp
.getPredicate();
7156 Value
*LHS
= Cmp
.getOperand(0), *RHS
= Cmp
.getOperand(1);
7159 auto createCmpReverse
= [&](CmpInst::Predicate Pred
, Value
*X
, Value
*Y
) {
7160 Value
*V
= Builder
.CreateCmp(Pred
, X
, Y
, Cmp
.getName());
7161 if (auto *I
= dyn_cast
<Instruction
>(V
))
7162 I
->copyIRFlags(&Cmp
);
7163 Module
*M
= Cmp
.getModule();
7164 Function
*F
= Intrinsic::getOrInsertDeclaration(
7165 M
, Intrinsic::vector_reverse
, V
->getType());
7166 return CallInst::Create(F
, V
);
7169 if (match(LHS
, m_VecReverse(m_Value(V1
)))) {
7170 // cmp Pred, rev(V1), rev(V2) --> rev(cmp Pred, V1, V2)
7171 if (match(RHS
, m_VecReverse(m_Value(V2
))) &&
7172 (LHS
->hasOneUse() || RHS
->hasOneUse()))
7173 return createCmpReverse(Pred
, V1
, V2
);
7175 // cmp Pred, rev(V1), RHSSplat --> rev(cmp Pred, V1, RHSSplat)
7176 if (LHS
->hasOneUse() && isSplatValue(RHS
))
7177 return createCmpReverse(Pred
, V1
, RHS
);
7179 // cmp Pred, LHSSplat, rev(V2) --> rev(cmp Pred, LHSSplat, V2)
7180 else if (isSplatValue(LHS
) && match(RHS
, m_OneUse(m_VecReverse(m_Value(V2
)))))
7181 return createCmpReverse(Pred
, LHS
, V2
);
7184 if (!match(LHS
, m_Shuffle(m_Value(V1
), m_Undef(), m_Mask(M
))))
7187 // If both arguments of the cmp are shuffles that use the same mask and
7188 // shuffle within a single vector, move the shuffle after the cmp:
7189 // cmp (shuffle V1, M), (shuffle V2, M) --> shuffle (cmp V1, V2), M
7190 Type
*V1Ty
= V1
->getType();
7191 if (match(RHS
, m_Shuffle(m_Value(V2
), m_Undef(), m_SpecificMask(M
))) &&
7192 V1Ty
== V2
->getType() && (LHS
->hasOneUse() || RHS
->hasOneUse())) {
7193 Value
*NewCmp
= Builder
.CreateCmp(Pred
, V1
, V2
);
7194 return new ShuffleVectorInst(NewCmp
, M
);
7197 // Try to canonicalize compare with splatted operand and splat constant.
7198 // TODO: We could generalize this for more than splats. See/use the code in
7199 // InstCombiner::foldVectorBinop().
7201 if (!LHS
->hasOneUse() || !match(RHS
, m_Constant(C
)))
7204 // Length-changing splats are ok, so adjust the constants as needed:
7205 // cmp (shuffle V1, M), C --> shuffle (cmp V1, C'), M
7206 Constant
*ScalarC
= C
->getSplatValue(/* AllowPoison */ true);
7208 if (ScalarC
&& match(M
, m_SplatOrPoisonMask(MaskSplatIndex
))) {
7209 // We allow poison in matching, but this transform removes it for safety.
7210 // Demanded elements analysis should be able to recover some/all of that.
7211 C
= ConstantVector::getSplat(cast
<VectorType
>(V1Ty
)->getElementCount(),
7213 SmallVector
<int, 8> NewM(M
.size(), MaskSplatIndex
);
7214 Value
*NewCmp
= Builder
.CreateCmp(Pred
, V1
, C
);
7215 return new ShuffleVectorInst(NewCmp
, NewM
);
7221 // extract(uadd.with.overflow(A, B), 0) ult A
7222 // -> extract(uadd.with.overflow(A, B), 1)
7223 static Instruction
*foldICmpOfUAddOv(ICmpInst
&I
) {
7224 CmpInst::Predicate Pred
= I
.getPredicate();
7225 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
7229 auto UAddOvResultPat
= m_ExtractValue
<0>(
7230 m_Intrinsic
<Intrinsic::uadd_with_overflow
>(m_Value(A
), m_Value(B
)));
7231 if (match(Op0
, UAddOvResultPat
) &&
7232 ((Pred
== ICmpInst::ICMP_ULT
&& (Op1
== A
|| Op1
== B
)) ||
7233 (Pred
== ICmpInst::ICMP_EQ
&& match(Op1
, m_ZeroInt()) &&
7234 (match(A
, m_One()) || match(B
, m_One()))) ||
7235 (Pred
== ICmpInst::ICMP_NE
&& match(Op1
, m_AllOnes()) &&
7236 (match(A
, m_AllOnes()) || match(B
, m_AllOnes())))))
7237 // extract(uadd.with.overflow(A, B), 0) < A
7238 // extract(uadd.with.overflow(A, 1), 0) == 0
7239 // extract(uadd.with.overflow(A, -1), 0) != -1
7240 UAddOv
= cast
<ExtractValueInst
>(Op0
)->getAggregateOperand();
7241 else if (match(Op1
, UAddOvResultPat
) &&
7242 Pred
== ICmpInst::ICMP_UGT
&& (Op0
== A
|| Op0
== B
))
7243 // A > extract(uadd.with.overflow(A, B), 0)
7244 UAddOv
= cast
<ExtractValueInst
>(Op1
)->getAggregateOperand();
7248 return ExtractValueInst::Create(UAddOv
, 1);
7251 static Instruction
*foldICmpInvariantGroup(ICmpInst
&I
) {
7252 if (!I
.getOperand(0)->getType()->isPointerTy() ||
7253 NullPointerIsDefined(
7254 I
.getParent()->getParent(),
7255 I
.getOperand(0)->getType()->getPointerAddressSpace())) {
7259 if (match(I
.getOperand(0), m_Instruction(Op
)) &&
7260 match(I
.getOperand(1), m_Zero()) &&
7261 Op
->isLaunderOrStripInvariantGroup()) {
7262 return ICmpInst::Create(Instruction::ICmp
, I
.getPredicate(),
7263 Op
->getOperand(0), I
.getOperand(1));
7268 /// This function folds patterns produced by lowering of reduce idioms, such as
7269 /// llvm.vector.reduce.and which are lowered into instruction chains. This code
7270 /// attempts to generate fewer number of scalar comparisons instead of vector
7271 /// comparisons when possible.
7272 static Instruction
*foldReductionIdiom(ICmpInst
&I
,
7273 InstCombiner::BuilderTy
&Builder
,
7274 const DataLayout
&DL
) {
7275 if (I
.getType()->isVectorTy())
7277 CmpPredicate OuterPred
, InnerPred
;
7280 // Match lowering of @llvm.vector.reduce.and. Turn
7281 /// %vec_ne = icmp ne <8 x i8> %lhs, %rhs
7282 /// %scalar_ne = bitcast <8 x i1> %vec_ne to i8
7283 /// %res = icmp <pred> i8 %scalar_ne, 0
7287 /// %lhs.scalar = bitcast <8 x i8> %lhs to i64
7288 /// %rhs.scalar = bitcast <8 x i8> %rhs to i64
7289 /// %res = icmp <pred> i64 %lhs.scalar, %rhs.scalar
7291 /// for <pred> in {ne, eq}.
7292 if (!match(&I
, m_ICmp(OuterPred
,
7293 m_OneUse(m_BitCast(m_OneUse(
7294 m_ICmp(InnerPred
, m_Value(LHS
), m_Value(RHS
))))),
7297 auto *LHSTy
= dyn_cast
<FixedVectorType
>(LHS
->getType());
7298 if (!LHSTy
|| !LHSTy
->getElementType()->isIntegerTy())
7301 LHSTy
->getNumElements() * LHSTy
->getElementType()->getIntegerBitWidth();
7302 // TODO: Relax this to "not wider than max legal integer type"?
7303 if (!DL
.isLegalInteger(NumBits
))
7306 if (ICmpInst::isEquality(OuterPred
) && InnerPred
== ICmpInst::ICMP_NE
) {
7307 auto *ScalarTy
= Builder
.getIntNTy(NumBits
);
7308 LHS
= Builder
.CreateBitCast(LHS
, ScalarTy
, LHS
->getName() + ".scalar");
7309 RHS
= Builder
.CreateBitCast(RHS
, ScalarTy
, RHS
->getName() + ".scalar");
7310 return ICmpInst::Create(Instruction::ICmp
, OuterPred
, LHS
, RHS
,
7317 // This helper will be called with icmp operands in both orders.
7318 Instruction
*InstCombinerImpl::foldICmpCommutative(CmpPredicate Pred
,
7319 Value
*Op0
, Value
*Op1
,
7321 // Try to optimize 'icmp GEP, P' or 'icmp P, GEP'.
7322 if (auto *GEP
= dyn_cast
<GEPOperator
>(Op0
))
7323 if (Instruction
*NI
= foldGEPICmp(GEP
, Op1
, Pred
, CxtI
))
7326 if (auto *SI
= dyn_cast
<SelectInst
>(Op0
))
7327 if (Instruction
*NI
= foldSelectICmp(Pred
, SI
, Op1
, CxtI
))
7330 if (auto *MinMax
= dyn_cast
<MinMaxIntrinsic
>(Op0
))
7331 if (Instruction
*Res
= foldICmpWithMinMax(CxtI
, MinMax
, Op1
, Pred
))
7338 if (match(Op0
, m_Add(m_Value(X
), m_APInt(C
))) && Op1
== X
)
7339 return foldICmpAddOpConst(X
, *C
, Pred
);
7342 // abs(X) >= X --> true
7343 // abs(X) u<= X --> true
7344 // abs(X) < X --> false
7345 // abs(X) u> X --> false
7346 // abs(X) u>= X --> IsIntMinPosion ? `X > -1`: `X u<= INTMIN`
7347 // abs(X) <= X --> IsIntMinPosion ? `X > -1`: `X u<= INTMIN`
7348 // abs(X) == X --> IsIntMinPosion ? `X > -1`: `X u<= INTMIN`
7349 // abs(X) u< X --> IsIntMinPosion ? `X < 0` : `X > INTMIN`
7350 // abs(X) > X --> IsIntMinPosion ? `X < 0` : `X > INTMIN`
7351 // abs(X) != X --> IsIntMinPosion ? `X < 0` : `X > INTMIN`
7355 if (match(Op0
, m_Intrinsic
<Intrinsic::abs
>(m_Value(X
), m_Constant(C
))) &&
7356 match(Op1
, m_Specific(X
))) {
7357 Value
*NullValue
= Constant::getNullValue(X
->getType());
7358 Value
*AllOnesValue
= Constant::getAllOnesValue(X
->getType());
7360 APInt::getSignedMinValue(X
->getType()->getScalarSizeInBits());
7361 bool IsIntMinPosion
= C
->isAllOnesValue();
7363 case CmpInst::ICMP_ULE
:
7364 case CmpInst::ICMP_SGE
:
7365 return replaceInstUsesWith(CxtI
, ConstantInt::getTrue(CxtI
.getType()));
7366 case CmpInst::ICMP_UGT
:
7367 case CmpInst::ICMP_SLT
:
7368 return replaceInstUsesWith(CxtI
, ConstantInt::getFalse(CxtI
.getType()));
7369 case CmpInst::ICMP_UGE
:
7370 case CmpInst::ICMP_SLE
:
7371 case CmpInst::ICMP_EQ
: {
7372 return replaceInstUsesWith(
7373 CxtI
, IsIntMinPosion
7374 ? Builder
.CreateICmpSGT(X
, AllOnesValue
)
7375 : Builder
.CreateICmpULT(
7376 X
, ConstantInt::get(X
->getType(), SMin
+ 1)));
7378 case CmpInst::ICMP_ULT
:
7379 case CmpInst::ICMP_SGT
:
7380 case CmpInst::ICMP_NE
: {
7381 return replaceInstUsesWith(
7382 CxtI
, IsIntMinPosion
7383 ? Builder
.CreateICmpSLT(X
, NullValue
)
7384 : Builder
.CreateICmpUGT(
7385 X
, ConstantInt::get(X
->getType(), SMin
)));
7388 llvm_unreachable("Invalid predicate!");
7393 const SimplifyQuery Q
= SQ
.getWithInstruction(&CxtI
);
7394 if (Value
*V
= foldICmpWithLowBitMaskedVal(Pred
, Op0
, Op1
, Q
, *this))
7395 return replaceInstUsesWith(CxtI
, V
);
7397 // Folding (X / Y) pred X => X swap(pred) 0 for constant Y other than 0 or 1
7398 auto CheckUGT1
= [](const APInt
&Divisor
) { return Divisor
.ugt(1); };
7400 if (match(Op0
, m_UDiv(m_Specific(Op1
), m_CheckedInt(CheckUGT1
)))) {
7401 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), Op1
,
7402 Constant::getNullValue(Op1
->getType()));
7405 if (!ICmpInst::isUnsigned(Pred
) &&
7406 match(Op0
, m_SDiv(m_Specific(Op1
), m_CheckedInt(CheckUGT1
)))) {
7407 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), Op1
,
7408 Constant::getNullValue(Op1
->getType()));
7412 // Another case of this fold is (X >> Y) pred X => X swap(pred) 0 if Y != 0
7413 auto CheckNE0
= [](const APInt
&Shift
) { return !Shift
.isZero(); };
7415 if (match(Op0
, m_LShr(m_Specific(Op1
), m_CheckedInt(CheckNE0
)))) {
7416 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), Op1
,
7417 Constant::getNullValue(Op1
->getType()));
7420 if ((Pred
== CmpInst::ICMP_SLT
|| Pred
== CmpInst::ICMP_SGE
) &&
7421 match(Op0
, m_AShr(m_Specific(Op1
), m_CheckedInt(CheckNE0
)))) {
7422 return new ICmpInst(ICmpInst::getSwappedPredicate(Pred
), Op1
,
7423 Constant::getNullValue(Op1
->getType()));
7430 Instruction
*InstCombinerImpl::visitICmpInst(ICmpInst
&I
) {
7431 bool Changed
= false;
7432 const SimplifyQuery Q
= SQ
.getWithInstruction(&I
);
7433 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
7434 unsigned Op0Cplxity
= getComplexity(Op0
);
7435 unsigned Op1Cplxity
= getComplexity(Op1
);
7437 /// Orders the operands of the compare so that they are listed from most
7438 /// complex to least complex. This puts constants before unary operators,
7439 /// before binary operators.
7440 if (Op0Cplxity
< Op1Cplxity
) {
7442 std::swap(Op0
, Op1
);
7446 if (Value
*V
= simplifyICmpInst(I
.getCmpPredicate(), Op0
, Op1
, Q
))
7447 return replaceInstUsesWith(I
, V
);
7449 // Comparing -val or val with non-zero is the same as just comparing val
7450 // ie, abs(val) != 0 -> val != 0
7451 if (I
.getPredicate() == ICmpInst::ICMP_NE
&& match(Op1
, m_Zero())) {
7452 Value
*Cond
, *SelectTrue
, *SelectFalse
;
7453 if (match(Op0
, m_Select(m_Value(Cond
), m_Value(SelectTrue
),
7454 m_Value(SelectFalse
)))) {
7455 if (Value
*V
= dyn_castNegVal(SelectTrue
)) {
7456 if (V
== SelectFalse
)
7457 return CmpInst::Create(Instruction::ICmp
, I
.getPredicate(), V
, Op1
);
7459 else if (Value
*V
= dyn_castNegVal(SelectFalse
)) {
7460 if (V
== SelectTrue
)
7461 return CmpInst::Create(Instruction::ICmp
, I
.getPredicate(), V
, Op1
);
7466 if (Op0
->getType()->isIntOrIntVectorTy(1))
7467 if (Instruction
*Res
= canonicalizeICmpBool(I
, Builder
))
7470 if (Instruction
*Res
= canonicalizeCmpWithConstant(I
))
7473 if (Instruction
*Res
= canonicalizeICmpPredicate(I
))
7476 if (Instruction
*Res
= foldICmpWithConstant(I
))
7479 if (Instruction
*Res
= foldICmpWithDominatingICmp(I
))
7482 if (Instruction
*Res
= foldICmpUsingBoolRange(I
))
7485 if (Instruction
*Res
= foldICmpUsingKnownBits(I
))
7488 if (Instruction
*Res
= foldICmpTruncWithTruncOrExt(I
, Q
))
7491 // Test if the ICmpInst instruction is used exclusively by a select as
7492 // part of a minimum or maximum operation. If so, refrain from doing
7493 // any other folding. This helps out other analyses which understand
7494 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
7495 // and CodeGen. And in this case, at least one of the comparison
7496 // operands has at least one user besides the compare (the select),
7497 // which would often largely negate the benefit of folding anyway.
7499 // Do the same for the other patterns recognized by matchSelectPattern.
7501 if (SelectInst
*SI
= dyn_cast
<SelectInst
>(I
.user_back())) {
7503 SelectPatternResult SPR
= matchSelectPattern(SI
, A
, B
);
7504 if (SPR
.Flavor
!= SPF_UNKNOWN
)
7508 // Do this after checking for min/max to prevent infinite looping.
7509 if (Instruction
*Res
= foldICmpWithZero(I
))
7512 // FIXME: We only do this after checking for min/max to prevent infinite
7513 // looping caused by a reverse canonicalization of these patterns for min/max.
7514 // FIXME: The organization of folds is a mess. These would naturally go into
7515 // canonicalizeCmpWithConstant(), but we can't move all of the above folds
7516 // down here after the min/max restriction.
7517 ICmpInst::Predicate Pred
= I
.getPredicate();
7519 if (match(Op1
, m_APInt(C
))) {
7520 // For i32: x >u 2147483647 -> x <s 0 -> true if sign bit set
7521 if (Pred
== ICmpInst::ICMP_UGT
&& C
->isMaxSignedValue()) {
7522 Constant
*Zero
= Constant::getNullValue(Op0
->getType());
7523 return new ICmpInst(ICmpInst::ICMP_SLT
, Op0
, Zero
);
7526 // For i32: x <u 2147483648 -> x >s -1 -> true if sign bit clear
7527 if (Pred
== ICmpInst::ICMP_ULT
&& C
->isMinSignedValue()) {
7528 Constant
*AllOnes
= Constant::getAllOnesValue(Op0
->getType());
7529 return new ICmpInst(ICmpInst::ICMP_SGT
, Op0
, AllOnes
);
7533 // The folds in here may rely on wrapping flags and special constants, so
7534 // they can break up min/max idioms in some cases but not seemingly similar
7536 // FIXME: It may be possible to enhance select folding to make this
7537 // unnecessary. It may also be moot if we canonicalize to min/max
7539 if (Instruction
*Res
= foldICmpBinOp(I
, Q
))
7542 if (Instruction
*Res
= foldICmpInstWithConstant(I
))
7545 // Try to match comparison as a sign bit test. Intentionally do this after
7546 // foldICmpInstWithConstant() to potentially let other folds to happen first.
7547 if (Instruction
*New
= foldSignBitTest(I
))
7550 if (Instruction
*Res
= foldICmpInstWithConstantNotInt(I
))
7553 if (Instruction
*Res
= foldICmpCommutative(I
.getCmpPredicate(), Op0
, Op1
, I
))
7555 if (Instruction
*Res
=
7556 foldICmpCommutative(I
.getSwappedCmpPredicate(), Op1
, Op0
, I
))
7559 if (I
.isCommutative()) {
7560 if (auto Pair
= matchSymmetricPair(I
.getOperand(0), I
.getOperand(1))) {
7561 replaceOperand(I
, 0, Pair
->first
);
7562 replaceOperand(I
, 1, Pair
->second
);
7567 // In case of a comparison with two select instructions having the same
7568 // condition, check whether one of the resulting branches can be simplified.
7569 // If so, just compare the other branch and select the appropriate result.
7571 // %tmp1 = select i1 %cmp, i32 %y, i32 %x
7572 // %tmp2 = select i1 %cmp, i32 %z, i32 %x
7573 // %cmp2 = icmp slt i32 %tmp2, %tmp1
7574 // The icmp will result false for the false value of selects and the result
7575 // will depend upon the comparison of true values of selects if %cmp is
7576 // true. Thus, transform this into:
7577 // %cmp = icmp slt i32 %y, %z
7578 // %sel = select i1 %cond, i1 %cmp, i1 false
7579 // This handles similar cases to transform.
7581 Value
*Cond
, *A
, *B
, *C
, *D
;
7582 if (match(Op0
, m_Select(m_Value(Cond
), m_Value(A
), m_Value(B
))) &&
7583 match(Op1
, m_Select(m_Specific(Cond
), m_Value(C
), m_Value(D
))) &&
7584 (Op0
->hasOneUse() || Op1
->hasOneUse())) {
7585 // Check whether comparison of TrueValues can be simplified
7586 if (Value
*Res
= simplifyICmpInst(Pred
, A
, C
, SQ
)) {
7587 Value
*NewICMP
= Builder
.CreateICmp(Pred
, B
, D
);
7588 return SelectInst::Create(Cond
, Res
, NewICMP
);
7590 // Check whether comparison of FalseValues can be simplified
7591 if (Value
*Res
= simplifyICmpInst(Pred
, B
, D
, SQ
)) {
7592 Value
*NewICMP
= Builder
.CreateICmp(Pred
, A
, C
);
7593 return SelectInst::Create(Cond
, NewICMP
, Res
);
7598 // Try to optimize equality comparisons against alloca-based pointers.
7599 if (Op0
->getType()->isPointerTy() && I
.isEquality()) {
7600 assert(Op1
->getType()->isPointerTy() && "Comparing pointer with non-pointer?");
7601 if (auto *Alloca
= dyn_cast
<AllocaInst
>(getUnderlyingObject(Op0
)))
7602 if (foldAllocaCmp(Alloca
))
7604 if (auto *Alloca
= dyn_cast
<AllocaInst
>(getUnderlyingObject(Op1
)))
7605 if (foldAllocaCmp(Alloca
))
7609 if (Instruction
*Res
= foldICmpBitCast(I
))
7612 // TODO: Hoist this above the min/max bailout.
7613 if (Instruction
*R
= foldICmpWithCastOp(I
))
7618 // Transform (X & ~Y) == 0 --> (X & Y) != 0
7619 // and (X & ~Y) != 0 --> (X & Y) == 0
7620 // if A is a power of 2.
7621 if (match(Op0
, m_And(m_Value(X
), m_Not(m_Value(Y
)))) &&
7622 match(Op1
, m_Zero()) && isKnownToBeAPowerOfTwo(X
, false, 0, &I
) &&
7624 return new ICmpInst(I
.getInversePredicate(), Builder
.CreateAnd(X
, Y
),
7627 // Op0 pred Op1 -> ~Op1 pred ~Op0, if this allows us to drop an instruction.
7628 if (Op0
->getType()->isIntOrIntVectorTy()) {
7629 bool ConsumesOp0
, ConsumesOp1
;
7630 if (isFreeToInvert(Op0
, Op0
->hasOneUse(), ConsumesOp0
) &&
7631 isFreeToInvert(Op1
, Op1
->hasOneUse(), ConsumesOp1
) &&
7632 (ConsumesOp0
|| ConsumesOp1
)) {
7633 Value
*InvOp0
= getFreelyInverted(Op0
, Op0
->hasOneUse(), &Builder
);
7634 Value
*InvOp1
= getFreelyInverted(Op1
, Op1
->hasOneUse(), &Builder
);
7635 assert(InvOp0
&& InvOp1
&&
7636 "Mismatch between isFreeToInvert and getFreelyInverted");
7637 return new ICmpInst(I
.getSwappedPredicate(), InvOp0
, InvOp1
);
7641 Instruction
*AddI
= nullptr;
7642 if (match(&I
, m_UAddWithOverflow(m_Value(X
), m_Value(Y
),
7643 m_Instruction(AddI
))) &&
7644 isa
<IntegerType
>(X
->getType())) {
7647 // m_UAddWithOverflow can match patterns that do not include an explicit
7648 // "add" instruction, so check the opcode of the matched op.
7649 if (AddI
->getOpcode() == Instruction::Add
&&
7650 OptimizeOverflowCheck(Instruction::Add
, /*Signed*/ false, X
, Y
, *AddI
,
7651 Result
, Overflow
)) {
7652 replaceInstUsesWith(*AddI
, Result
);
7653 eraseInstFromFunction(*AddI
);
7654 return replaceInstUsesWith(I
, Overflow
);
7658 // (zext X) * (zext Y) --> llvm.umul.with.overflow.
7659 if (match(Op0
, m_NUWMul(m_ZExt(m_Value(X
)), m_ZExt(m_Value(Y
)))) &&
7660 match(Op1
, m_APInt(C
))) {
7661 if (Instruction
*R
= processUMulZExtIdiom(I
, Op0
, C
, *this))
7665 // Signbit test folds
7666 // Fold (X u>> BitWidth - 1 Pred ZExt(i1)) --> X s< 0 Pred i1
7667 // Fold (X s>> BitWidth - 1 Pred SExt(i1)) --> X s< 0 Pred i1
7669 if ((I
.isUnsigned() || I
.isEquality()) &&
7671 m_CombineAnd(m_Instruction(ExtI
), m_ZExtOrSExt(m_Value(Y
)))) &&
7672 Y
->getType()->getScalarSizeInBits() == 1 &&
7673 (Op0
->hasOneUse() || Op1
->hasOneUse())) {
7674 unsigned OpWidth
= Op0
->getType()->getScalarSizeInBits();
7675 Instruction
*ShiftI
;
7676 if (match(Op0
, m_CombineAnd(m_Instruction(ShiftI
),
7677 m_Shr(m_Value(X
), m_SpecificIntAllowPoison(
7679 unsigned ExtOpc
= ExtI
->getOpcode();
7680 unsigned ShiftOpc
= ShiftI
->getOpcode();
7681 if ((ExtOpc
== Instruction::ZExt
&& ShiftOpc
== Instruction::LShr
) ||
7682 (ExtOpc
== Instruction::SExt
&& ShiftOpc
== Instruction::AShr
)) {
7684 Builder
.CreateICmpSLT(X
, Constant::getNullValue(X
->getType()));
7685 Value
*Cmp
= Builder
.CreateICmp(Pred
, SLTZero
, Y
, I
.getName());
7686 return replaceInstUsesWith(I
, Cmp
);
7692 if (Instruction
*Res
= foldICmpEquality(I
))
7695 if (Instruction
*Res
= foldICmpPow2Test(I
, Builder
))
7698 if (Instruction
*Res
= foldICmpOfUAddOv(I
))
7701 // The 'cmpxchg' instruction returns an aggregate containing the old value and
7702 // an i1 which indicates whether or not we successfully did the swap.
7704 // Replace comparisons between the old value and the expected value with the
7705 // indicator that 'cmpxchg' returns.
7707 // N.B. This transform is only valid when the 'cmpxchg' is not permitted to
7708 // spuriously fail. In those cases, the old value may equal the expected
7709 // value but it is possible for the swap to not occur.
7710 if (I
.getPredicate() == ICmpInst::ICMP_EQ
)
7711 if (auto *EVI
= dyn_cast
<ExtractValueInst
>(Op0
))
7712 if (auto *ACXI
= dyn_cast
<AtomicCmpXchgInst
>(EVI
->getAggregateOperand()))
7713 if (EVI
->getIndices()[0] == 0 && ACXI
->getCompareOperand() == Op1
&&
7715 return ExtractValueInst::Create(ACXI
, 1);
7717 if (Instruction
*Res
= foldICmpWithHighBitMask(I
, Builder
))
7720 if (I
.getType()->isVectorTy())
7721 if (Instruction
*Res
= foldVectorCmp(I
, Builder
))
7724 if (Instruction
*Res
= foldICmpInvariantGroup(I
))
7727 if (Instruction
*Res
= foldReductionIdiom(I
, Builder
, DL
))
7732 const APInt
*C1
, *C2
;
7733 ICmpInst::Predicate Pred
= I
.getPredicate();
7734 if (ICmpInst::isEquality(Pred
)) {
7735 // sext(a) & c1 == c2 --> a & c3 == trunc(c2)
7736 // sext(a) & c1 != c2 --> a & c3 != trunc(c2)
7737 if (match(Op0
, m_And(m_SExt(m_Value(A
)), m_APInt(C1
))) &&
7738 match(Op1
, m_APInt(C2
))) {
7739 Type
*InputTy
= A
->getType();
7740 unsigned InputBitWidth
= InputTy
->getScalarSizeInBits();
7741 // c2 must be non-negative at the bitwidth of a.
7742 if (C2
->getActiveBits() < InputBitWidth
) {
7743 APInt TruncC1
= C1
->trunc(InputBitWidth
);
7744 // Check if there are 1s in C1 high bits of size InputBitWidth.
7745 if (C1
->uge(APInt::getOneBitSet(C1
->getBitWidth(), InputBitWidth
)))
7746 TruncC1
.setBit(InputBitWidth
- 1);
7747 Value
*AndInst
= Builder
.CreateAnd(A
, TruncC1
);
7748 return new ICmpInst(
7750 ConstantInt::get(InputTy
, C2
->trunc(InputBitWidth
)));
7756 return Changed
? &I
: nullptr;
7759 /// Fold fcmp ([us]itofp x, cst) if possible.
7760 Instruction
*InstCombinerImpl::foldFCmpIntToFPConst(FCmpInst
&I
,
7764 if (!match(RHSC
, m_APFloat(RHS
)))
7767 // Get the width of the mantissa. We don't want to hack on conversions that
7768 // might lose information from the integer, e.g. "i64 -> float"
7769 int MantissaWidth
= LHSI
->getType()->getFPMantissaWidth();
7770 if (MantissaWidth
== -1) return nullptr; // Unknown.
7772 Type
*IntTy
= LHSI
->getOperand(0)->getType();
7773 unsigned IntWidth
= IntTy
->getScalarSizeInBits();
7774 bool LHSUnsigned
= isa
<UIToFPInst
>(LHSI
);
7776 if (I
.isEquality()) {
7777 FCmpInst::Predicate P
= I
.getPredicate();
7778 bool IsExact
= false;
7779 APSInt
RHSCvt(IntWidth
, LHSUnsigned
);
7780 RHS
->convertToInteger(RHSCvt
, APFloat::rmNearestTiesToEven
, &IsExact
);
7782 // If the floating point constant isn't an integer value, we know if we will
7783 // ever compare equal / not equal to it.
7785 // TODO: Can never be -0.0 and other non-representable values
7786 APFloat
RHSRoundInt(*RHS
);
7787 RHSRoundInt
.roundToIntegral(APFloat::rmNearestTiesToEven
);
7788 if (*RHS
!= RHSRoundInt
) {
7789 if (P
== FCmpInst::FCMP_OEQ
|| P
== FCmpInst::FCMP_UEQ
)
7790 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7792 assert(P
== FCmpInst::FCMP_ONE
|| P
== FCmpInst::FCMP_UNE
);
7793 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7797 // TODO: If the constant is exactly representable, is it always OK to do
7798 // equality compares as integer?
7801 // Check to see that the input is converted from an integer type that is small
7802 // enough that preserves all bits. TODO: check here for "known" sign bits.
7803 // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
7805 // Following test does NOT adjust IntWidth downwards for signed inputs,
7806 // because the most negative value still requires all the mantissa bits
7807 // to distinguish it from one less than that value.
7808 if ((int)IntWidth
> MantissaWidth
) {
7809 // Conversion would lose accuracy. Check if loss can impact comparison.
7810 int Exp
= ilogb(*RHS
);
7811 if (Exp
== APFloat::IEK_Inf
) {
7812 int MaxExponent
= ilogb(APFloat::getLargest(RHS
->getSemantics()));
7813 if (MaxExponent
< (int)IntWidth
- !LHSUnsigned
)
7814 // Conversion could create infinity.
7817 // Note that if RHS is zero or NaN, then Exp is negative
7818 // and first condition is trivially false.
7819 if (MantissaWidth
<= Exp
&& Exp
<= (int)IntWidth
- !LHSUnsigned
)
7820 // Conversion could affect comparison.
7825 // Otherwise, we can potentially simplify the comparison. We know that it
7826 // will always come through as an integer value and we know the constant is
7827 // not a NAN (it would have been previously simplified).
7828 assert(!RHS
->isNaN() && "NaN comparison not already folded!");
7830 ICmpInst::Predicate Pred
;
7831 switch (I
.getPredicate()) {
7832 default: llvm_unreachable("Unexpected predicate!");
7833 case FCmpInst::FCMP_UEQ
:
7834 case FCmpInst::FCMP_OEQ
:
7835 Pred
= ICmpInst::ICMP_EQ
;
7837 case FCmpInst::FCMP_UGT
:
7838 case FCmpInst::FCMP_OGT
:
7839 Pred
= LHSUnsigned
? ICmpInst::ICMP_UGT
: ICmpInst::ICMP_SGT
;
7841 case FCmpInst::FCMP_UGE
:
7842 case FCmpInst::FCMP_OGE
:
7843 Pred
= LHSUnsigned
? ICmpInst::ICMP_UGE
: ICmpInst::ICMP_SGE
;
7845 case FCmpInst::FCMP_ULT
:
7846 case FCmpInst::FCMP_OLT
:
7847 Pred
= LHSUnsigned
? ICmpInst::ICMP_ULT
: ICmpInst::ICMP_SLT
;
7849 case FCmpInst::FCMP_ULE
:
7850 case FCmpInst::FCMP_OLE
:
7851 Pred
= LHSUnsigned
? ICmpInst::ICMP_ULE
: ICmpInst::ICMP_SLE
;
7853 case FCmpInst::FCMP_UNE
:
7854 case FCmpInst::FCMP_ONE
:
7855 Pred
= ICmpInst::ICMP_NE
;
7857 case FCmpInst::FCMP_ORD
:
7858 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7859 case FCmpInst::FCMP_UNO
:
7860 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7863 // Now we know that the APFloat is a normal number, zero or inf.
7865 // See if the FP constant is too large for the integer. For example,
7866 // comparing an i8 to 300.0.
7868 // If the RHS value is > SignedMax, fold the comparison. This handles +INF
7869 // and large values.
7870 APFloat
SMax(RHS
->getSemantics());
7871 SMax
.convertFromAPInt(APInt::getSignedMaxValue(IntWidth
), true,
7872 APFloat::rmNearestTiesToEven
);
7873 if (SMax
< *RHS
) { // smax < 13123.0
7874 if (Pred
== ICmpInst::ICMP_NE
|| Pred
== ICmpInst::ICMP_SLT
||
7875 Pred
== ICmpInst::ICMP_SLE
)
7876 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7877 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7880 // If the RHS value is > UnsignedMax, fold the comparison. This handles
7881 // +INF and large values.
7882 APFloat
UMax(RHS
->getSemantics());
7883 UMax
.convertFromAPInt(APInt::getMaxValue(IntWidth
), false,
7884 APFloat::rmNearestTiesToEven
);
7885 if (UMax
< *RHS
) { // umax < 13123.0
7886 if (Pred
== ICmpInst::ICMP_NE
|| Pred
== ICmpInst::ICMP_ULT
||
7887 Pred
== ICmpInst::ICMP_ULE
)
7888 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7889 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7894 // See if the RHS value is < SignedMin.
7895 APFloat
SMin(RHS
->getSemantics());
7896 SMin
.convertFromAPInt(APInt::getSignedMinValue(IntWidth
), true,
7897 APFloat::rmNearestTiesToEven
);
7898 if (SMin
> *RHS
) { // smin > 12312.0
7899 if (Pred
== ICmpInst::ICMP_NE
|| Pred
== ICmpInst::ICMP_SGT
||
7900 Pred
== ICmpInst::ICMP_SGE
)
7901 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7902 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7905 // See if the RHS value is < UnsignedMin.
7906 APFloat
UMin(RHS
->getSemantics());
7907 UMin
.convertFromAPInt(APInt::getMinValue(IntWidth
), false,
7908 APFloat::rmNearestTiesToEven
);
7909 if (UMin
> *RHS
) { // umin > 12312.0
7910 if (Pred
== ICmpInst::ICMP_NE
|| Pred
== ICmpInst::ICMP_UGT
||
7911 Pred
== ICmpInst::ICMP_UGE
)
7912 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7913 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7917 // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
7918 // [0, UMAX], but it may still be fractional. Check whether this is the case
7919 // using the IsExact flag.
7920 // Don't do this for zero, because -0.0 is not fractional.
7921 APSInt
RHSInt(IntWidth
, LHSUnsigned
);
7923 RHS
->convertToInteger(RHSInt
, APFloat::rmTowardZero
, &IsExact
);
7924 if (!RHS
->isZero()) {
7926 // If we had a comparison against a fractional value, we have to adjust
7927 // the compare predicate and sometimes the value. RHSC is rounded towards
7928 // zero at this point.
7930 default: llvm_unreachable("Unexpected integer comparison!");
7931 case ICmpInst::ICMP_NE
: // (float)int != 4.4 --> true
7932 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7933 case ICmpInst::ICMP_EQ
: // (float)int == 4.4 --> false
7934 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7935 case ICmpInst::ICMP_ULE
:
7936 // (float)int <= 4.4 --> int <= 4
7937 // (float)int <= -4.4 --> false
7938 if (RHS
->isNegative())
7939 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7941 case ICmpInst::ICMP_SLE
:
7942 // (float)int <= 4.4 --> int <= 4
7943 // (float)int <= -4.4 --> int < -4
7944 if (RHS
->isNegative())
7945 Pred
= ICmpInst::ICMP_SLT
;
7947 case ICmpInst::ICMP_ULT
:
7948 // (float)int < -4.4 --> false
7949 // (float)int < 4.4 --> int <= 4
7950 if (RHS
->isNegative())
7951 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
7952 Pred
= ICmpInst::ICMP_ULE
;
7954 case ICmpInst::ICMP_SLT
:
7955 // (float)int < -4.4 --> int < -4
7956 // (float)int < 4.4 --> int <= 4
7957 if (!RHS
->isNegative())
7958 Pred
= ICmpInst::ICMP_SLE
;
7960 case ICmpInst::ICMP_UGT
:
7961 // (float)int > 4.4 --> int > 4
7962 // (float)int > -4.4 --> true
7963 if (RHS
->isNegative())
7964 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7966 case ICmpInst::ICMP_SGT
:
7967 // (float)int > 4.4 --> int > 4
7968 // (float)int > -4.4 --> int >= -4
7969 if (RHS
->isNegative())
7970 Pred
= ICmpInst::ICMP_SGE
;
7972 case ICmpInst::ICMP_UGE
:
7973 // (float)int >= -4.4 --> true
7974 // (float)int >= 4.4 --> int > 4
7975 if (RHS
->isNegative())
7976 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
7977 Pred
= ICmpInst::ICMP_UGT
;
7979 case ICmpInst::ICMP_SGE
:
7980 // (float)int >= -4.4 --> int >= -4
7981 // (float)int >= 4.4 --> int > 4
7982 if (!RHS
->isNegative())
7983 Pred
= ICmpInst::ICMP_SGT
;
7989 // Lower this FP comparison into an appropriate integer version of the
7991 return new ICmpInst(Pred
, LHSI
->getOperand(0),
7992 ConstantInt::get(LHSI
->getOperand(0)->getType(), RHSInt
));
7995 /// Fold (C / X) < 0.0 --> X < 0.0 if possible. Swap predicate if necessary.
7996 static Instruction
*foldFCmpReciprocalAndZero(FCmpInst
&I
, Instruction
*LHSI
,
7998 // When C is not 0.0 and infinities are not allowed:
7999 // (C / X) < 0.0 is a sign-bit test of X
8000 // (C / X) < 0.0 --> X < 0.0 (if C is positive)
8001 // (C / X) < 0.0 --> X > 0.0 (if C is negative, swap the predicate)
8004 // Multiply (C / X) < 0.0 by X * X / C.
8005 // - X is non zero, if it is the flag 'ninf' is violated.
8006 // - C defines the sign of X * X * C. Thus it also defines whether to swap
8007 // the predicate. C is also non zero by definition.
8009 // Thus X * X / C is non zero and the transformation is valid. [qed]
8011 FCmpInst::Predicate Pred
= I
.getPredicate();
8013 // Check that predicates are valid.
8014 if ((Pred
!= FCmpInst::FCMP_OGT
) && (Pred
!= FCmpInst::FCMP_OLT
) &&
8015 (Pred
!= FCmpInst::FCMP_OGE
) && (Pred
!= FCmpInst::FCMP_OLE
))
8018 // Check that RHS operand is zero.
8019 if (!match(RHSC
, m_AnyZeroFP()))
8022 // Check fastmath flags ('ninf').
8023 if (!LHSI
->hasNoInfs() || !I
.hasNoInfs())
8026 // Check the properties of the dividend. It must not be zero to avoid a
8027 // division by zero (see Proof).
8029 if (!match(LHSI
->getOperand(0), m_APFloat(C
)))
8035 // Get swapped predicate if necessary.
8036 if (C
->isNegative())
8037 Pred
= I
.getSwappedPredicate();
8039 return new FCmpInst(Pred
, LHSI
->getOperand(1), RHSC
, "", &I
);
8042 /// Optimize fabs(X) compared with zero.
8043 static Instruction
*foldFabsWithFcmpZero(FCmpInst
&I
, InstCombinerImpl
&IC
) {
8045 if (!match(I
.getOperand(0), m_FAbs(m_Value(X
))))
8049 if (!match(I
.getOperand(1), m_APFloat(C
)))
8052 if (!C
->isPosZero()) {
8053 if (!C
->isSmallestNormalized())
8056 const Function
*F
= I
.getFunction();
8057 DenormalMode Mode
= F
->getDenormalMode(C
->getSemantics());
8058 if (Mode
.Input
== DenormalMode::PreserveSign
||
8059 Mode
.Input
== DenormalMode::PositiveZero
) {
8061 auto replaceFCmp
= [](FCmpInst
*I
, FCmpInst::Predicate P
, Value
*X
) {
8062 Constant
*Zero
= ConstantFP::getZero(X
->getType());
8063 return new FCmpInst(P
, X
, Zero
, "", I
);
8066 switch (I
.getPredicate()) {
8067 case FCmpInst::FCMP_OLT
:
8068 // fcmp olt fabs(x), smallest_normalized_number -> fcmp oeq x, 0.0
8069 return replaceFCmp(&I
, FCmpInst::FCMP_OEQ
, X
);
8070 case FCmpInst::FCMP_UGE
:
8071 // fcmp uge fabs(x), smallest_normalized_number -> fcmp une x, 0.0
8072 return replaceFCmp(&I
, FCmpInst::FCMP_UNE
, X
);
8073 case FCmpInst::FCMP_OGE
:
8074 // fcmp oge fabs(x), smallest_normalized_number -> fcmp one x, 0.0
8075 return replaceFCmp(&I
, FCmpInst::FCMP_ONE
, X
);
8076 case FCmpInst::FCMP_ULT
:
8077 // fcmp ult fabs(x), smallest_normalized_number -> fcmp ueq x, 0.0
8078 return replaceFCmp(&I
, FCmpInst::FCMP_UEQ
, X
);
8087 auto replacePredAndOp0
= [&IC
](FCmpInst
*I
, FCmpInst::Predicate P
, Value
*X
) {
8089 return IC
.replaceOperand(*I
, 0, X
);
8092 switch (I
.getPredicate()) {
8093 case FCmpInst::FCMP_UGE
:
8094 case FCmpInst::FCMP_OLT
:
8095 // fabs(X) >= 0.0 --> true
8096 // fabs(X) < 0.0 --> false
8097 llvm_unreachable("fcmp should have simplified");
8099 case FCmpInst::FCMP_OGT
:
8100 // fabs(X) > 0.0 --> X != 0.0
8101 return replacePredAndOp0(&I
, FCmpInst::FCMP_ONE
, X
);
8103 case FCmpInst::FCMP_UGT
:
8104 // fabs(X) u> 0.0 --> X u!= 0.0
8105 return replacePredAndOp0(&I
, FCmpInst::FCMP_UNE
, X
);
8107 case FCmpInst::FCMP_OLE
:
8108 // fabs(X) <= 0.0 --> X == 0.0
8109 return replacePredAndOp0(&I
, FCmpInst::FCMP_OEQ
, X
);
8111 case FCmpInst::FCMP_ULE
:
8112 // fabs(X) u<= 0.0 --> X u== 0.0
8113 return replacePredAndOp0(&I
, FCmpInst::FCMP_UEQ
, X
);
8115 case FCmpInst::FCMP_OGE
:
8116 // fabs(X) >= 0.0 --> !isnan(X)
8117 assert(!I
.hasNoNaNs() && "fcmp should have simplified");
8118 return replacePredAndOp0(&I
, FCmpInst::FCMP_ORD
, X
);
8120 case FCmpInst::FCMP_ULT
:
8121 // fabs(X) u< 0.0 --> isnan(X)
8122 assert(!I
.hasNoNaNs() && "fcmp should have simplified");
8123 return replacePredAndOp0(&I
, FCmpInst::FCMP_UNO
, X
);
8125 case FCmpInst::FCMP_OEQ
:
8126 case FCmpInst::FCMP_UEQ
:
8127 case FCmpInst::FCMP_ONE
:
8128 case FCmpInst::FCMP_UNE
:
8129 case FCmpInst::FCMP_ORD
:
8130 case FCmpInst::FCMP_UNO
:
8131 // Look through the fabs() because it doesn't change anything but the sign.
8132 // fabs(X) == 0.0 --> X == 0.0,
8133 // fabs(X) != 0.0 --> X != 0.0
8134 // isnan(fabs(X)) --> isnan(X)
8135 // !isnan(fabs(X) --> !isnan(X)
8136 return replacePredAndOp0(&I
, I
.getPredicate(), X
);
8143 /// Optimize sqrt(X) compared with zero.
8144 static Instruction
*foldSqrtWithFcmpZero(FCmpInst
&I
, InstCombinerImpl
&IC
) {
8146 if (!match(I
.getOperand(0), m_Sqrt(m_Value(X
))))
8149 if (!match(I
.getOperand(1), m_PosZeroFP()))
8152 auto ReplacePredAndOp0
= [&](FCmpInst::Predicate P
) {
8154 return IC
.replaceOperand(I
, 0, X
);
8157 // Clear ninf flag if sqrt doesn't have it.
8158 if (!cast
<Instruction
>(I
.getOperand(0))->hasNoInfs())
8159 I
.setHasNoInfs(false);
8161 switch (I
.getPredicate()) {
8162 case FCmpInst::FCMP_OLT
:
8163 case FCmpInst::FCMP_UGE
:
8164 // sqrt(X) < 0.0 --> false
8165 // sqrt(X) u>= 0.0 --> true
8166 llvm_unreachable("fcmp should have simplified");
8167 case FCmpInst::FCMP_ULT
:
8168 case FCmpInst::FCMP_ULE
:
8169 case FCmpInst::FCMP_OGT
:
8170 case FCmpInst::FCMP_OGE
:
8171 case FCmpInst::FCMP_OEQ
:
8172 case FCmpInst::FCMP_UNE
:
8173 // sqrt(X) u< 0.0 --> X u< 0.0
8174 // sqrt(X) u<= 0.0 --> X u<= 0.0
8175 // sqrt(X) > 0.0 --> X > 0.0
8176 // sqrt(X) >= 0.0 --> X >= 0.0
8177 // sqrt(X) == 0.0 --> X == 0.0
8178 // sqrt(X) u!= 0.0 --> X u!= 0.0
8179 return IC
.replaceOperand(I
, 0, X
);
8181 case FCmpInst::FCMP_OLE
:
8182 // sqrt(X) <= 0.0 --> X == 0.0
8183 return ReplacePredAndOp0(FCmpInst::FCMP_OEQ
);
8184 case FCmpInst::FCMP_UGT
:
8185 // sqrt(X) u> 0.0 --> X u!= 0.0
8186 return ReplacePredAndOp0(FCmpInst::FCMP_UNE
);
8187 case FCmpInst::FCMP_UEQ
:
8188 // sqrt(X) u== 0.0 --> X u<= 0.0
8189 return ReplacePredAndOp0(FCmpInst::FCMP_ULE
);
8190 case FCmpInst::FCMP_ONE
:
8191 // sqrt(X) != 0.0 --> X > 0.0
8192 return ReplacePredAndOp0(FCmpInst::FCMP_OGT
);
8193 case FCmpInst::FCMP_ORD
:
8194 // !isnan(sqrt(X)) --> X >= 0.0
8195 return ReplacePredAndOp0(FCmpInst::FCMP_OGE
);
8196 case FCmpInst::FCMP_UNO
:
8197 // isnan(sqrt(X)) --> X u< 0.0
8198 return ReplacePredAndOp0(FCmpInst::FCMP_ULT
);
8200 llvm_unreachable("Unexpected predicate!");
8204 static Instruction
*foldFCmpFNegCommonOp(FCmpInst
&I
) {
8205 CmpInst::Predicate Pred
= I
.getPredicate();
8206 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
8208 // Canonicalize fneg as Op1.
8209 if (match(Op0
, m_FNeg(m_Value())) && !match(Op1
, m_FNeg(m_Value()))) {
8210 std::swap(Op0
, Op1
);
8211 Pred
= I
.getSwappedPredicate();
8214 if (!match(Op1
, m_FNeg(m_Specific(Op0
))))
8217 // Replace the negated operand with 0.0:
8218 // fcmp Pred Op0, -Op0 --> fcmp Pred Op0, 0.0
8219 Constant
*Zero
= ConstantFP::getZero(Op0
->getType());
8220 return new FCmpInst(Pred
, Op0
, Zero
, "", &I
);
8223 static Instruction
*foldFCmpFSubIntoFCmp(FCmpInst
&I
, Instruction
*LHSI
,
8224 Constant
*RHSC
, InstCombinerImpl
&CI
) {
8225 const CmpInst::Predicate Pred
= I
.getPredicate();
8226 Value
*X
= LHSI
->getOperand(0);
8227 Value
*Y
= LHSI
->getOperand(1);
8231 case FCmpInst::FCMP_UGT
:
8232 case FCmpInst::FCMP_ULT
:
8233 case FCmpInst::FCMP_UNE
:
8234 case FCmpInst::FCMP_OEQ
:
8235 case FCmpInst::FCMP_OGE
:
8236 case FCmpInst::FCMP_OLE
:
8237 // The optimization is not valid if X and Y are infinities of the same
8238 // sign, i.e. the inf - inf = nan case. If the fsub has the ninf or nnan
8239 // flag then we can assume we do not have that case. Otherwise we might be
8240 // able to prove that either X or Y is not infinity.
8241 if (!LHSI
->hasNoNaNs() && !LHSI
->hasNoInfs() &&
8242 !isKnownNeverInfinity(Y
, /*Depth=*/0,
8243 CI
.getSimplifyQuery().getWithInstruction(&I
)) &&
8244 !isKnownNeverInfinity(X
, /*Depth=*/0,
8245 CI
.getSimplifyQuery().getWithInstruction(&I
)))
8249 case FCmpInst::FCMP_OGT
:
8250 case FCmpInst::FCMP_OLT
:
8251 case FCmpInst::FCMP_ONE
:
8252 case FCmpInst::FCMP_UEQ
:
8253 case FCmpInst::FCMP_UGE
:
8254 case FCmpInst::FCMP_ULE
:
8255 // fcmp pred (x - y), 0 --> fcmp pred x, y
8256 if (match(RHSC
, m_AnyZeroFP()) &&
8257 I
.getFunction()->getDenormalMode(
8258 LHSI
->getType()->getScalarType()->getFltSemantics()) ==
8259 DenormalMode::getIEEE()) {
8260 CI
.replaceOperand(I
, 0, X
);
8261 CI
.replaceOperand(I
, 1, Y
);
8270 static Instruction
*foldFCmpWithFloorAndCeil(FCmpInst
&I
,
8271 InstCombinerImpl
&IC
) {
8272 Value
*LHS
= I
.getOperand(0), *RHS
= I
.getOperand(1);
8273 Type
*OpType
= LHS
->getType();
8274 CmpInst::Predicate Pred
= I
.getPredicate();
8276 bool FloorX
= match(LHS
, m_Intrinsic
<Intrinsic::floor
>(m_Specific(RHS
)));
8277 bool CeilX
= match(LHS
, m_Intrinsic
<Intrinsic::ceil
>(m_Specific(RHS
)));
8279 if (!FloorX
&& !CeilX
) {
8280 if ((FloorX
= match(RHS
, m_Intrinsic
<Intrinsic::floor
>(m_Specific(LHS
)))) ||
8281 (CeilX
= match(RHS
, m_Intrinsic
<Intrinsic::ceil
>(m_Specific(LHS
))))) {
8282 std::swap(LHS
, RHS
);
8283 Pred
= I
.getSwappedPredicate();
8288 case FCmpInst::FCMP_OLE
:
8289 // fcmp ole floor(x), x => fcmp ord x, 0
8291 return new FCmpInst(FCmpInst::FCMP_ORD
, RHS
, ConstantFP::getZero(OpType
),
8294 case FCmpInst::FCMP_OGT
:
8295 // fcmp ogt floor(x), x => false
8297 return IC
.replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
8299 case FCmpInst::FCMP_OGE
:
8300 // fcmp oge ceil(x), x => fcmp ord x, 0
8302 return new FCmpInst(FCmpInst::FCMP_ORD
, RHS
, ConstantFP::getZero(OpType
),
8305 case FCmpInst::FCMP_OLT
:
8306 // fcmp olt ceil(x), x => false
8308 return IC
.replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
8310 case FCmpInst::FCMP_ULE
:
8311 // fcmp ule floor(x), x => true
8313 return IC
.replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
8315 case FCmpInst::FCMP_UGT
:
8316 // fcmp ugt floor(x), x => fcmp uno x, 0
8318 return new FCmpInst(FCmpInst::FCMP_UNO
, RHS
, ConstantFP::getZero(OpType
),
8321 case FCmpInst::FCMP_UGE
:
8322 // fcmp uge ceil(x), x => true
8324 return IC
.replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
8326 case FCmpInst::FCMP_ULT
:
8327 // fcmp ult ceil(x), x => fcmp uno x, 0
8329 return new FCmpInst(FCmpInst::FCMP_UNO
, RHS
, ConstantFP::getZero(OpType
),
8339 Instruction
*InstCombinerImpl::visitFCmpInst(FCmpInst
&I
) {
8340 bool Changed
= false;
8342 /// Orders the operands of the compare so that they are listed from most
8343 /// complex to least complex. This puts constants before unary operators,
8344 /// before binary operators.
8345 if (getComplexity(I
.getOperand(0)) < getComplexity(I
.getOperand(1))) {
8350 const CmpInst::Predicate Pred
= I
.getPredicate();
8351 Value
*Op0
= I
.getOperand(0), *Op1
= I
.getOperand(1);
8352 if (Value
*V
= simplifyFCmpInst(Pred
, Op0
, Op1
, I
.getFastMathFlags(),
8353 SQ
.getWithInstruction(&I
)))
8354 return replaceInstUsesWith(I
, V
);
8356 // Simplify 'fcmp pred X, X'
8357 Type
*OpType
= Op0
->getType();
8358 assert(OpType
== Op1
->getType() && "fcmp with different-typed operands?");
8362 case FCmpInst::FCMP_UNO
: // True if unordered: isnan(X) | isnan(Y)
8363 case FCmpInst::FCMP_ULT
: // True if unordered or less than
8364 case FCmpInst::FCMP_UGT
: // True if unordered or greater than
8365 case FCmpInst::FCMP_UNE
: // True if unordered or not equal
8366 // Canonicalize these to be 'fcmp uno %X, 0.0'.
8367 I
.setPredicate(FCmpInst::FCMP_UNO
);
8368 I
.setOperand(1, Constant::getNullValue(OpType
));
8371 case FCmpInst::FCMP_ORD
: // True if ordered (no nans)
8372 case FCmpInst::FCMP_OEQ
: // True if ordered and equal
8373 case FCmpInst::FCMP_OGE
: // True if ordered and greater than or equal
8374 case FCmpInst::FCMP_OLE
: // True if ordered and less than or equal
8375 // Canonicalize these to be 'fcmp ord %X, 0.0'.
8376 I
.setPredicate(FCmpInst::FCMP_ORD
);
8377 I
.setOperand(1, Constant::getNullValue(OpType
));
8382 if (I
.isCommutative()) {
8383 if (auto Pair
= matchSymmetricPair(I
.getOperand(0), I
.getOperand(1))) {
8384 replaceOperand(I
, 0, Pair
->first
);
8385 replaceOperand(I
, 1, Pair
->second
);
8390 // If we're just checking for a NaN (ORD/UNO) and have a non-NaN operand,
8391 // then canonicalize the operand to 0.0.
8392 if (Pred
== CmpInst::FCMP_ORD
|| Pred
== CmpInst::FCMP_UNO
) {
8393 if (!match(Op0
, m_PosZeroFP()) &&
8394 isKnownNeverNaN(Op0
, 0, getSimplifyQuery().getWithInstruction(&I
)))
8395 return replaceOperand(I
, 0, ConstantFP::getZero(OpType
));
8397 if (!match(Op1
, m_PosZeroFP()) &&
8398 isKnownNeverNaN(Op1
, 0, getSimplifyQuery().getWithInstruction(&I
)))
8399 return replaceOperand(I
, 1, ConstantFP::getZero(OpType
));
8402 // fcmp pred (fneg X), (fneg Y) -> fcmp swap(pred) X, Y
8404 if (match(Op0
, m_FNeg(m_Value(X
))) && match(Op1
, m_FNeg(m_Value(Y
))))
8405 return new FCmpInst(I
.getSwappedPredicate(), X
, Y
, "", &I
);
8407 if (Instruction
*R
= foldFCmpFNegCommonOp(I
))
8410 // Test if the FCmpInst instruction is used exclusively by a select as
8411 // part of a minimum or maximum operation. If so, refrain from doing
8412 // any other folding. This helps out other analyses which understand
8413 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
8414 // and CodeGen. And in this case, at least one of the comparison
8415 // operands has at least one user besides the compare (the select),
8416 // which would often largely negate the benefit of folding anyway.
8418 if (SelectInst
*SI
= dyn_cast
<SelectInst
>(I
.user_back())) {
8420 SelectPatternResult SPR
= matchSelectPattern(SI
, A
, B
);
8421 if (SPR
.Flavor
!= SPF_UNKNOWN
)
8425 // The sign of 0.0 is ignored by fcmp, so canonicalize to +0.0:
8426 // fcmp Pred X, -0.0 --> fcmp Pred X, 0.0
8427 if (match(Op1
, m_AnyZeroFP()) && !match(Op1
, m_PosZeroFP()))
8428 return replaceOperand(I
, 1, ConstantFP::getZero(OpType
));
8431 // fcmp olt X, +inf -> fcmp one X, +inf
8432 // fcmp ole X, +inf -> fcmp ord X, 0
8433 // fcmp ogt X, +inf -> false
8434 // fcmp oge X, +inf -> fcmp oeq X, +inf
8435 // fcmp ult X, +inf -> fcmp une X, +inf
8436 // fcmp ule X, +inf -> true
8437 // fcmp ugt X, +inf -> fcmp uno X, 0
8438 // fcmp uge X, +inf -> fcmp ueq X, +inf
8439 // fcmp olt X, -inf -> false
8440 // fcmp ole X, -inf -> fcmp oeq X, -inf
8441 // fcmp ogt X, -inf -> fcmp one X, -inf
8442 // fcmp oge X, -inf -> fcmp ord X, 0
8443 // fcmp ult X, -inf -> fcmp uno X, 0
8444 // fcmp ule X, -inf -> fcmp ueq X, -inf
8445 // fcmp ugt X, -inf -> fcmp une X, -inf
8446 // fcmp uge X, -inf -> true
8448 if (match(Op1
, m_APFloat(C
)) && C
->isInfinity()) {
8449 switch (C
->isNegative() ? FCmpInst::getSwappedPredicate(Pred
) : Pred
) {
8452 case FCmpInst::FCMP_ORD
:
8453 case FCmpInst::FCMP_UNO
:
8454 case FCmpInst::FCMP_TRUE
:
8455 case FCmpInst::FCMP_FALSE
:
8456 case FCmpInst::FCMP_OGT
:
8457 case FCmpInst::FCMP_ULE
:
8458 llvm_unreachable("Should be simplified by InstSimplify");
8459 case FCmpInst::FCMP_OLT
:
8460 return new FCmpInst(FCmpInst::FCMP_ONE
, Op0
, Op1
, "", &I
);
8461 case FCmpInst::FCMP_OLE
:
8462 return new FCmpInst(FCmpInst::FCMP_ORD
, Op0
, ConstantFP::getZero(OpType
),
8464 case FCmpInst::FCMP_OGE
:
8465 return new FCmpInst(FCmpInst::FCMP_OEQ
, Op0
, Op1
, "", &I
);
8466 case FCmpInst::FCMP_ULT
:
8467 return new FCmpInst(FCmpInst::FCMP_UNE
, Op0
, Op1
, "", &I
);
8468 case FCmpInst::FCMP_UGT
:
8469 return new FCmpInst(FCmpInst::FCMP_UNO
, Op0
, ConstantFP::getZero(OpType
),
8471 case FCmpInst::FCMP_UGE
:
8472 return new FCmpInst(FCmpInst::FCMP_UEQ
, Op0
, Op1
, "", &I
);
8476 // Ignore signbit of bitcasted int when comparing equality to FP 0.0:
8477 // fcmp oeq/une (bitcast X), 0.0 --> (and X, SignMaskC) ==/!= 0
8478 if (match(Op1
, m_PosZeroFP()) &&
8479 match(Op0
, m_OneUse(m_ElementWiseBitCast(m_Value(X
))))) {
8480 ICmpInst::Predicate IntPred
= ICmpInst::BAD_ICMP_PREDICATE
;
8481 if (Pred
== FCmpInst::FCMP_OEQ
)
8482 IntPred
= ICmpInst::ICMP_EQ
;
8483 else if (Pred
== FCmpInst::FCMP_UNE
)
8484 IntPred
= ICmpInst::ICMP_NE
;
8486 if (IntPred
!= ICmpInst::BAD_ICMP_PREDICATE
) {
8487 Type
*IntTy
= X
->getType();
8488 const APInt
&SignMask
= ~APInt::getSignMask(IntTy
->getScalarSizeInBits());
8489 Value
*MaskX
= Builder
.CreateAnd(X
, ConstantInt::get(IntTy
, SignMask
));
8490 return new ICmpInst(IntPred
, MaskX
, ConstantInt::getNullValue(IntTy
));
8494 // Handle fcmp with instruction LHS and constant RHS.
8497 if (match(Op0
, m_Instruction(LHSI
)) && match(Op1
, m_Constant(RHSC
))) {
8498 switch (LHSI
->getOpcode()) {
8499 case Instruction::Select
:
8500 // fcmp eq (cond ? x : -x), 0 --> fcmp eq x, 0
8501 if (FCmpInst::isEquality(Pred
) && match(RHSC
, m_AnyZeroFP()) &&
8502 match(LHSI
, m_c_Select(m_FNeg(m_Value(X
)), m_Deferred(X
))))
8503 return replaceOperand(I
, 0, X
);
8504 if (Instruction
*NV
= FoldOpIntoSelect(I
, cast
<SelectInst
>(LHSI
)))
8507 case Instruction::FSub
:
8508 if (LHSI
->hasOneUse())
8509 if (Instruction
*NV
= foldFCmpFSubIntoFCmp(I
, LHSI
, RHSC
, *this))
8512 case Instruction::PHI
:
8513 if (Instruction
*NV
= foldOpIntoPhi(I
, cast
<PHINode
>(LHSI
)))
8516 case Instruction::SIToFP
:
8517 case Instruction::UIToFP
:
8518 if (Instruction
*NV
= foldFCmpIntToFPConst(I
, LHSI
, RHSC
))
8521 case Instruction::FDiv
:
8522 if (Instruction
*NV
= foldFCmpReciprocalAndZero(I
, LHSI
, RHSC
))
8525 case Instruction::Load
:
8526 if (auto *GEP
= dyn_cast
<GetElementPtrInst
>(LHSI
->getOperand(0)))
8527 if (auto *GV
= dyn_cast
<GlobalVariable
>(GEP
->getOperand(0)))
8528 if (Instruction
*Res
= foldCmpLoadFromIndexedGlobal(
8529 cast
<LoadInst
>(LHSI
), GEP
, GV
, I
))
8535 if (Instruction
*R
= foldFabsWithFcmpZero(I
, *this))
8538 if (Instruction
*R
= foldSqrtWithFcmpZero(I
, *this))
8541 if (Instruction
*R
= foldFCmpWithFloorAndCeil(I
, *this))
8544 if (match(Op0
, m_FNeg(m_Value(X
)))) {
8545 // fcmp pred (fneg X), C --> fcmp swap(pred) X, -C
8547 if (match(Op1
, m_Constant(C
)))
8548 if (Constant
*NegC
= ConstantFoldUnaryOpOperand(Instruction::FNeg
, C
, DL
))
8549 return new FCmpInst(I
.getSwappedPredicate(), X
, NegC
, "", &I
);
8552 // fcmp (fadd X, 0.0), Y --> fcmp X, Y
8553 if (match(Op0
, m_FAdd(m_Value(X
), m_AnyZeroFP())))
8554 return new FCmpInst(Pred
, X
, Op1
, "", &I
);
8556 // fcmp X, (fadd Y, 0.0) --> fcmp X, Y
8557 if (match(Op1
, m_FAdd(m_Value(Y
), m_AnyZeroFP())))
8558 return new FCmpInst(Pred
, Op0
, Y
, "", &I
);
8560 if (match(Op0
, m_FPExt(m_Value(X
)))) {
8561 // fcmp (fpext X), (fpext Y) -> fcmp X, Y
8562 if (match(Op1
, m_FPExt(m_Value(Y
))) && X
->getType() == Y
->getType())
8563 return new FCmpInst(Pred
, X
, Y
, "", &I
);
8566 if (match(Op1
, m_APFloat(C
))) {
8567 const fltSemantics
&FPSem
=
8568 X
->getType()->getScalarType()->getFltSemantics();
8570 APFloat TruncC
= *C
;
8571 TruncC
.convert(FPSem
, APFloat::rmNearestTiesToEven
, &Lossy
);
8574 // X can't possibly equal the higher-precision constant, so reduce any
8575 // equality comparison.
8576 // TODO: Other predicates can be handled via getFCmpCode().
8578 case FCmpInst::FCMP_OEQ
:
8579 // X is ordered and equal to an impossible constant --> false
8580 return replaceInstUsesWith(I
, ConstantInt::getFalse(I
.getType()));
8581 case FCmpInst::FCMP_ONE
:
8582 // X is ordered and not equal to an impossible constant --> ordered
8583 return new FCmpInst(FCmpInst::FCMP_ORD
, X
,
8584 ConstantFP::getZero(X
->getType()));
8585 case FCmpInst::FCMP_UEQ
:
8586 // X is unordered or equal to an impossible constant --> unordered
8587 return new FCmpInst(FCmpInst::FCMP_UNO
, X
,
8588 ConstantFP::getZero(X
->getType()));
8589 case FCmpInst::FCMP_UNE
:
8590 // X is unordered or not equal to an impossible constant --> true
8591 return replaceInstUsesWith(I
, ConstantInt::getTrue(I
.getType()));
8597 // fcmp (fpext X), C -> fcmp X, (fptrunc C) if fptrunc is lossless
8598 // Avoid lossy conversions and denormals.
8599 // Zero is a special case that's OK to convert.
8600 APFloat Fabs
= TruncC
;
8603 (Fabs
.isZero() || !(Fabs
< APFloat::getSmallestNormalized(FPSem
)))) {
8604 Constant
*NewC
= ConstantFP::get(X
->getType(), TruncC
);
8605 return new FCmpInst(Pred
, X
, NewC
, "", &I
);
8610 // Convert a sign-bit test of an FP value into a cast and integer compare.
8611 // TODO: Simplify if the copysign constant is 0.0 or NaN.
8612 // TODO: Handle non-zero compare constants.
8613 // TODO: Handle other predicates.
8614 if (match(Op0
, m_OneUse(m_Intrinsic
<Intrinsic::copysign
>(m_APFloat(C
),
8616 match(Op1
, m_AnyZeroFP()) && !C
->isZero() && !C
->isNaN()) {
8617 Type
*IntType
= Builder
.getIntNTy(X
->getType()->getScalarSizeInBits());
8618 if (auto *VecTy
= dyn_cast
<VectorType
>(OpType
))
8619 IntType
= VectorType::get(IntType
, VecTy
->getElementCount());
8621 // copysign(non-zero constant, X) < 0.0 --> (bitcast X) < 0
8622 if (Pred
== FCmpInst::FCMP_OLT
) {
8623 Value
*IntX
= Builder
.CreateBitCast(X
, IntType
);
8624 return new ICmpInst(ICmpInst::ICMP_SLT
, IntX
,
8625 ConstantInt::getNullValue(IntType
));
8630 Value
*CanonLHS
= nullptr, *CanonRHS
= nullptr;
8631 match(Op0
, m_Intrinsic
<Intrinsic::canonicalize
>(m_Value(CanonLHS
)));
8632 match(Op1
, m_Intrinsic
<Intrinsic::canonicalize
>(m_Value(CanonRHS
)));
8634 // (canonicalize(x) == x) => (x == x)
8635 if (CanonLHS
== Op1
)
8636 return new FCmpInst(Pred
, Op1
, Op1
, "", &I
);
8638 // (x == canonicalize(x)) => (x == x)
8639 if (CanonRHS
== Op0
)
8640 return new FCmpInst(Pred
, Op0
, Op0
, "", &I
);
8642 // (canonicalize(x) == canonicalize(y)) => (x == y)
8643 if (CanonLHS
&& CanonRHS
)
8644 return new FCmpInst(Pred
, CanonLHS
, CanonRHS
, "", &I
);
8647 if (I
.getType()->isVectorTy())
8648 if (Instruction
*Res
= foldVectorCmp(I
, Builder
))
8651 return Changed
? &I
: nullptr;