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[InstCombine] Signed saturation patterns
[llvm-core.git] / lib / Target / X86 / X86FloatingPoint.cpp
blobfcfb5bc91314c649fe7563f642632632fab3a45a
1 //===-- X86FloatingPoint.cpp - Floating point Reg -> Stack converter ------===//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines the pass which converts floating point instructions from
10 // pseudo registers into register stack instructions. This pass uses live
11 // variable information to indicate where the FPn registers are used and their
12 // lifetimes.
13 //
14 // The x87 hardware tracks liveness of the stack registers, so it is necessary
15 // to implement exact liveness tracking between basic blocks. The CFG edges are
16 // partitioned into bundles where the same FP registers must be live in
17 // identical stack positions. Instructions are inserted at the end of each basic
18 // block to rearrange the live registers to match the outgoing bundle.
19 //
20 // This approach avoids splitting critical edges at the potential cost of more
21 // live register shuffling instructions when critical edges are present.
22 //
23 //===----------------------------------------------------------------------===//
24
25 #include "X86.h"
26 #include "X86InstrInfo.h"
27 #include "llvm/ADT/DepthFirstIterator.h"
28 #include "llvm/ADT/STLExtras.h"
29 #include "llvm/ADT/SmallPtrSet.h"
30 #include "llvm/ADT/SmallSet.h"
31 #include "llvm/ADT/SmallVector.h"
32 #include "llvm/ADT/Statistic.h"
33 #include "llvm/CodeGen/EdgeBundles.h"
34 #include "llvm/CodeGen/LivePhysRegs.h"
35 #include "llvm/CodeGen/MachineFunctionPass.h"
36 #include "llvm/CodeGen/MachineInstrBuilder.h"
37 #include "llvm/CodeGen/MachineRegisterInfo.h"
38 #include "llvm/CodeGen/Passes.h"
39 #include "llvm/CodeGen/TargetInstrInfo.h"
40 #include "llvm/CodeGen/TargetSubtargetInfo.h"
41 #include "llvm/Config/llvm-config.h"
42 #include "llvm/IR/InlineAsm.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/ErrorHandling.h"
45 #include "llvm/Support/raw_ostream.h"
46 #include "llvm/Target/TargetMachine.h"
47 #include <algorithm>
48 #include <bitset>
49 using namespace llvm;
50
51 #define DEBUG_TYPE "x86-codegen"
52
53 STATISTIC(NumFXCH, "Number of fxch instructions inserted");
54 STATISTIC(NumFP , "Number of floating point instructions");
55
56 namespace {
57 const unsigned ScratchFPReg = 7;
58
59 struct FPS : public MachineFunctionPass {
60 static char ID;
61 FPS() : MachineFunctionPass(ID) {
62 // This is really only to keep valgrind quiet.
63 // The logic in isLive() is too much for it.
64 memset(Stack, 0, sizeof(Stack));
65 memset(RegMap, 0, sizeof(RegMap));
66 }
67
68 void getAnalysisUsage(AnalysisUsage &AU) const override {
69 AU.setPreservesCFG();
70 AU.addRequired<EdgeBundles>();
71 AU.addPreservedID(MachineLoopInfoID);
72 AU.addPreservedID(MachineDominatorsID);
73 MachineFunctionPass::getAnalysisUsage(AU);
74 }
75
76 bool runOnMachineFunction(MachineFunction &MF) override;
77
78 MachineFunctionProperties getRequiredProperties() const override {
79 return MachineFunctionProperties().set(
80 MachineFunctionProperties::Property::NoVRegs);
81 }
82
83 StringRef getPassName() const override { return "X86 FP Stackifier"; }
84
85 private:
86 const TargetInstrInfo *TII; // Machine instruction info.
87
88 // Two CFG edges are related if they leave the same block, or enter the same
89 // block. The transitive closure of an edge under this relation is a
90 // LiveBundle. It represents a set of CFG edges where the live FP stack
91 // registers must be allocated identically in the x87 stack.
92 //
93 // A LiveBundle is usually all the edges leaving a block, or all the edges
94 // entering a block, but it can contain more edges if critical edges are
95 // present.
96 //
97 // The set of live FP registers in a LiveBundle is calculated by bundleCFG,
98 // but the exact mapping of FP registers to stack slots is fixed later.
99 struct LiveBundle {
100 // Bit mask of live FP registers. Bit 0 = FP0, bit 1 = FP1, &c.
101 unsigned Mask;
102
103 // Number of pre-assigned live registers in FixStack. This is 0 when the
104 // stack order has not yet been fixed.
105 unsigned FixCount;
106
107 // Assigned stack order for live-in registers.
108 // FixStack[i] == getStackEntry(i) for all i < FixCount.
109 unsigned char FixStack[8];
110
111 LiveBundle() : Mask(0), FixCount(0) {}
112
113 // Have the live registers been assigned a stack order yet?
114 bool isFixed() const { return !Mask || FixCount; }
115 };
116
117 // Numbered LiveBundle structs. LiveBundles[0] is used for all CFG edges
118 // with no live FP registers.
119 SmallVector<LiveBundle, 8> LiveBundles;
120
121 // The edge bundle analysis provides indices into the LiveBundles vector.
122 EdgeBundles *Bundles;
123
124 // Return a bitmask of FP registers in block's live-in list.
125 static unsigned calcLiveInMask(MachineBasicBlock *MBB, bool RemoveFPs) {
126 unsigned Mask = 0;
127 for (MachineBasicBlock::livein_iterator I = MBB->livein_begin();
128 I != MBB->livein_end(); ) {
129 MCPhysReg Reg = I->PhysReg;
130 static_assert(X86::FP6 - X86::FP0 == 6, "sequential regnums");
131 if (Reg >= X86::FP0 && Reg <= X86::FP6) {
132 Mask |= 1 << (Reg - X86::FP0);
133 if (RemoveFPs) {
134 I = MBB->removeLiveIn(I);
135 continue;
136 }
137 }
138 ++I;
139 }
140 return Mask;
141 }
142
143 // Partition all the CFG edges into LiveBundles.
144 void bundleCFGRecomputeKillFlags(MachineFunction &MF);
145
146 MachineBasicBlock *MBB; // Current basic block
147
148 // The hardware keeps track of how many FP registers are live, so we have
149 // to model that exactly. Usually, each live register corresponds to an
150 // FP<n> register, but when dealing with calls, returns, and inline
151 // assembly, it is sometimes necessary to have live scratch registers.
152 unsigned Stack[8]; // FP<n> Registers in each stack slot...
153 unsigned StackTop; // The current top of the FP stack.
154
155 enum {
156 NumFPRegs = 8 // Including scratch pseudo-registers.
157 };
158
159 // For each live FP<n> register, point to its Stack[] entry.
160 // The first entries correspond to FP0-FP6, the rest are scratch registers
161 // used when we need slightly different live registers than what the
162 // register allocator thinks.
163 unsigned RegMap[NumFPRegs];
164
165 // Set up our stack model to match the incoming registers to MBB.
166 void setupBlockStack();
167
168 // Shuffle live registers to match the expectations of successor blocks.
169 void finishBlockStack();
170
171 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
172 void dumpStack() const {
173 dbgs() << "Stack contents:";
174 for (unsigned i = 0; i != StackTop; ++i) {
175 dbgs() << " FP" << Stack[i];
176 assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!");
177 }
178 }
179 #endif
180
181 /// getSlot - Return the stack slot number a particular register number is
182 /// in.
183 unsigned getSlot(unsigned RegNo) const {
184 assert(RegNo < NumFPRegs && "Regno out of range!");
185 return RegMap[RegNo];
186 }
187
188 /// isLive - Is RegNo currently live in the stack?
189 bool isLive(unsigned RegNo) const {
190 unsigned Slot = getSlot(RegNo);
191 return Slot < StackTop && Stack[Slot] == RegNo;
192 }
193
194 /// getStackEntry - Return the X86::FP<n> register in register ST(i).
195 unsigned getStackEntry(unsigned STi) const {
196 if (STi >= StackTop)
197 report_fatal_error("Access past stack top!");
198 return Stack[StackTop-1-STi];
199 }
200
201 /// getSTReg - Return the X86::ST(i) register which contains the specified
202 /// FP<RegNo> register.
203 unsigned getSTReg(unsigned RegNo) const {
204 return StackTop - 1 - getSlot(RegNo) + X86::ST0;
205 }
206
207 // pushReg - Push the specified FP<n> register onto the stack.
208 void pushReg(unsigned Reg) {
209 assert(Reg < NumFPRegs && "Register number out of range!");
210 if (StackTop >= 8)
211 report_fatal_error("Stack overflow!");
212 Stack[StackTop] = Reg;
213 RegMap[Reg] = StackTop++;
214 }
215
216 // popReg - Pop a register from the stack.
217 void popReg() {
218 if (StackTop == 0)
219 report_fatal_error("Cannot pop empty stack!");
220 RegMap[Stack[--StackTop]] = ~0; // Update state
221 }
222
223 bool isAtTop(unsigned RegNo) const { return getSlot(RegNo) == StackTop-1; }
224 void moveToTop(unsigned RegNo, MachineBasicBlock::iterator I) {
225 DebugLoc dl = I == MBB->end() ? DebugLoc() : I->getDebugLoc();
226 if (isAtTop(RegNo)) return;
227
228 unsigned STReg = getSTReg(RegNo);
229 unsigned RegOnTop = getStackEntry(0);
230
231 // Swap the slots the regs are in.
232 std::swap(RegMap[RegNo], RegMap[RegOnTop]);
233
234 // Swap stack slot contents.
235 if (RegMap[RegOnTop] >= StackTop)
236 report_fatal_error("Access past stack top!");
237 std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
238
239 // Emit an fxch to update the runtime processors version of the state.
240 BuildMI(*MBB, I, dl, TII->get(X86::XCH_F)).addReg(STReg);
241 ++NumFXCH;
242 }
243
244 void duplicateToTop(unsigned RegNo, unsigned AsReg,
245 MachineBasicBlock::iterator I) {
246 DebugLoc dl = I == MBB->end() ? DebugLoc() : I->getDebugLoc();
247 unsigned STReg = getSTReg(RegNo);
248 pushReg(AsReg); // New register on top of stack
249
250 BuildMI(*MBB, I, dl, TII->get(X86::LD_Frr)).addReg(STReg);
251 }
252
253 /// popStackAfter - Pop the current value off of the top of the FP stack
254 /// after the specified instruction.
255 void popStackAfter(MachineBasicBlock::iterator &I);
256
257 /// freeStackSlotAfter - Free the specified register from the register
258 /// stack, so that it is no longer in a register. If the register is
259 /// currently at the top of the stack, we just pop the current instruction,
260 /// otherwise we store the current top-of-stack into the specified slot,
261 /// then pop the top of stack.
262 void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
263
264 /// freeStackSlotBefore - Just the pop, no folding. Return the inserted
265 /// instruction.
266 MachineBasicBlock::iterator
267 freeStackSlotBefore(MachineBasicBlock::iterator I, unsigned FPRegNo);
268
269 /// Adjust the live registers to be the set in Mask.
270 void adjustLiveRegs(unsigned Mask, MachineBasicBlock::iterator I);
271
272 /// Shuffle the top FixCount stack entries such that FP reg FixStack[0] is
273 /// st(0), FP reg FixStack[1] is st(1) etc.
274 void shuffleStackTop(const unsigned char *FixStack, unsigned FixCount,
275 MachineBasicBlock::iterator I);
276
277 bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
278
279 void handleCall(MachineBasicBlock::iterator &I);
280 void handleReturn(MachineBasicBlock::iterator &I);
281 void handleZeroArgFP(MachineBasicBlock::iterator &I);
282 void handleOneArgFP(MachineBasicBlock::iterator &I);
283 void handleOneArgFPRW(MachineBasicBlock::iterator &I);
284 void handleTwoArgFP(MachineBasicBlock::iterator &I);
285 void handleCompareFP(MachineBasicBlock::iterator &I);
286 void handleCondMovFP(MachineBasicBlock::iterator &I);
287 void handleSpecialFP(MachineBasicBlock::iterator &I);
288
289 // Check if a COPY instruction is using FP registers.
290 static bool isFPCopy(MachineInstr &MI) {
291 Register DstReg = MI.getOperand(0).getReg();
292 Register SrcReg = MI.getOperand(1).getReg();
293
294 return X86::RFP80RegClass.contains(DstReg) ||
295 X86::RFP80RegClass.contains(SrcReg);
296 }
297
298 void setKillFlags(MachineBasicBlock &MBB) const;
299 };
300 }
301
302 char FPS::ID = 0;
303
304 INITIALIZE_PASS_BEGIN(FPS, DEBUG_TYPE, "X86 FP Stackifier",
305 false, false)
306 INITIALIZE_PASS_DEPENDENCY(EdgeBundles)
307 INITIALIZE_PASS_END(FPS, DEBUG_TYPE, "X86 FP Stackifier",
308 false, false)
309
310 FunctionPass *llvm::createX86FloatingPointStackifierPass() { return new FPS(); }
311
312 /// getFPReg - Return the X86::FPx register number for the specified operand.
313 /// For example, this returns 3 for X86::FP3.
314 static unsigned getFPReg(const MachineOperand &MO) {
315 assert(MO.isReg() && "Expected an FP register!");
316 Register Reg = MO.getReg();
317 assert(Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!");
318 return Reg - X86::FP0;
319 }
320
321 /// runOnMachineFunction - Loop over all of the basic blocks, transforming FP
322 /// register references into FP stack references.
323 ///
324 bool FPS::runOnMachineFunction(MachineFunction &MF) {
325 // We only need to run this pass if there are any FP registers used in this
326 // function. If it is all integer, there is nothing for us to do!
327 bool FPIsUsed = false;
328
329 static_assert(X86::FP6 == X86::FP0+6, "Register enums aren't sorted right!");
330 const MachineRegisterInfo &MRI = MF.getRegInfo();
331 for (unsigned i = 0; i <= 6; ++i)
332 if (!MRI.reg_nodbg_empty(X86::FP0 + i)) {
333 FPIsUsed = true;
334 break;
335 }
336
337 // Early exit.
338 if (!FPIsUsed) return false;
339
340 Bundles = &getAnalysis<EdgeBundles>();
341 TII = MF.getSubtarget().getInstrInfo();
342
343 // Prepare cross-MBB liveness.
344 bundleCFGRecomputeKillFlags(MF);
345
346 StackTop = 0;
347
348 // Process the function in depth first order so that we process at least one
349 // of the predecessors for every reachable block in the function.
350 df_iterator_default_set<MachineBasicBlock*> Processed;
351 MachineBasicBlock *Entry = &MF.front();
352
353 LiveBundle &Bundle =
354 LiveBundles[Bundles->getBundle(Entry->getNumber(), false)];
355
356 // In regcall convention, some FP registers may not be passed through
357 // the stack, so they will need to be assigned to the stack first
358 if ((Entry->getParent()->getFunction().getCallingConv() ==
359 CallingConv::X86_RegCall) && (Bundle.Mask && !Bundle.FixCount)) {
360 // In the register calling convention, up to one FP argument could be
361 // saved in the first FP register.
362 // If bundle.mask is non-zero and Bundle.FixCount is zero, it means
363 // that the FP registers contain arguments.
364 // The actual value is passed in FP0.
365 // Here we fix the stack and mark FP0 as pre-assigned register.
366 assert((Bundle.Mask & 0xFE) == 0 &&
367 "Only FP0 could be passed as an argument");
368 Bundle.FixCount = 1;
369 Bundle.FixStack[0] = 0;
370 }
371
372 bool Changed = false;
373 for (MachineBasicBlock *BB : depth_first_ext(Entry, Processed))
374 Changed |= processBasicBlock(MF, *BB);
375
376 // Process any unreachable blocks in arbitrary order now.
377 if (MF.size() != Processed.size())
378 for (MachineBasicBlock &BB : MF)
379 if (Processed.insert(&BB).second)
380 Changed |= processBasicBlock(MF, BB);
381
382 LiveBundles.clear();
383
384 return Changed;
385 }
386
387 /// bundleCFG - Scan all the basic blocks to determine consistent live-in and
388 /// live-out sets for the FP registers. Consistent means that the set of
389 /// registers live-out from a block is identical to the live-in set of all
390 /// successors. This is not enforced by the normal live-in lists since
391 /// registers may be implicitly defined, or not used by all successors.
392 void FPS::bundleCFGRecomputeKillFlags(MachineFunction &MF) {
393 assert(LiveBundles.empty() && "Stale data in LiveBundles");
394 LiveBundles.resize(Bundles->getNumBundles());
395
396 // Gather the actual live-in masks for all MBBs.
397 for (MachineBasicBlock &MBB : MF) {
398 setKillFlags(MBB);
399
400 const unsigned Mask = calcLiveInMask(&MBB, false);
401 if (!Mask)
402 continue;
403 // Update MBB ingoing bundle mask.
404 LiveBundles[Bundles->getBundle(MBB.getNumber(), false)].Mask |= Mask;
405 }
406 }
407
408 /// processBasicBlock - Loop over all of the instructions in the basic block,
409 /// transforming FP instructions into their stack form.
410 ///
411 bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
412 bool Changed = false;
413 MBB = &BB;
414
415 setupBlockStack();
416
417 for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
418 MachineInstr &MI = *I;
419 uint64_t Flags = MI.getDesc().TSFlags;
420
421 unsigned FPInstClass = Flags & X86II::FPTypeMask;
422 if (MI.isInlineAsm())
423 FPInstClass = X86II::SpecialFP;
424
425 if (MI.isCopy() && isFPCopy(MI))
426 FPInstClass = X86II::SpecialFP;
427
428 if (MI.isImplicitDef() &&
429 X86::RFP80RegClass.contains(MI.getOperand(0).getReg()))
430 FPInstClass = X86II::SpecialFP;
431
432 if (MI.isCall())
433 FPInstClass = X86II::SpecialFP;
434
435 if (FPInstClass == X86II::NotFP)
436 continue; // Efficiently ignore non-fp insts!
437
438 MachineInstr *PrevMI = nullptr;
439 if (I != BB.begin())
440 PrevMI = &*std::prev(I);
441
442 ++NumFP; // Keep track of # of pseudo instrs
443 LLVM_DEBUG(dbgs() << "\nFPInst:\t" << MI);
444
445 // Get dead variables list now because the MI pointer may be deleted as part
446 // of processing!
447 SmallVector<unsigned, 8> DeadRegs;
448 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
449 const MachineOperand &MO = MI.getOperand(i);
450 if (MO.isReg() && MO.isDead())
451 DeadRegs.push_back(MO.getReg());
452 }
453
454 switch (FPInstClass) {
455 case X86II::ZeroArgFP: handleZeroArgFP(I); break;
456 case X86II::OneArgFP: handleOneArgFP(I); break; // fstp ST(0)
457 case X86II::OneArgFPRW: handleOneArgFPRW(I); break; // ST(0) = fsqrt(ST(0))
458 case X86II::TwoArgFP: handleTwoArgFP(I); break;
459 case X86II::CompareFP: handleCompareFP(I); break;
460 case X86II::CondMovFP: handleCondMovFP(I); break;
461 case X86II::SpecialFP: handleSpecialFP(I); break;
462 default: llvm_unreachable("Unknown FP Type!");
463 }
464
465 // Check to see if any of the values defined by this instruction are dead
466 // after definition. If so, pop them.
467 for (unsigned i = 0, e = DeadRegs.size(); i != e; ++i) {
468 unsigned Reg = DeadRegs[i];
469 // Check if Reg is live on the stack. An inline-asm register operand that
470 // is in the clobber list and marked dead might not be live on the stack.
471 static_assert(X86::FP7 - X86::FP0 == 7, "sequential FP regnumbers");
472 if (Reg >= X86::FP0 && Reg <= X86::FP6 && isLive(Reg-X86::FP0)) {
473 LLVM_DEBUG(dbgs() << "Register FP#" << Reg - X86::FP0 << " is dead!\n");
474 freeStackSlotAfter(I, Reg-X86::FP0);
475 }
476 }
477
478 // Print out all of the instructions expanded to if -debug
479 LLVM_DEBUG({
480 MachineBasicBlock::iterator PrevI = PrevMI;
481 if (I == PrevI) {
482 dbgs() << "Just deleted pseudo instruction\n";
483 } else {
484 MachineBasicBlock::iterator Start = I;
485 // Rewind to first instruction newly inserted.
486 while (Start != BB.begin() && std::prev(Start) != PrevI)
487 --Start;
488 dbgs() << "Inserted instructions:\n\t";
489 Start->print(dbgs());
490 while (++Start != std::next(I)) {
491 }
492 }
493 dumpStack();
494 });
495 (void)PrevMI;
496
497 Changed = true;
498 }
499
500 finishBlockStack();
501
502 return Changed;
503 }
504
505 /// setupBlockStack - Use the live bundles to set up our model of the stack
506 /// to match predecessors' live out stack.
507 void FPS::setupBlockStack() {
508 LLVM_DEBUG(dbgs() << "\nSetting up live-ins for " << printMBBReference(*MBB)
509 << " derived from " << MBB->getName() << ".\n");
510 StackTop = 0;
511 // Get the live-in bundle for MBB.
512 const LiveBundle &Bundle =
513 LiveBundles[Bundles->getBundle(MBB->getNumber(), false)];
514
515 if (!Bundle.Mask) {
516 LLVM_DEBUG(dbgs() << "Block has no FP live-ins.\n");
517 return;
518 }
519
520 // Depth-first iteration should ensure that we always have an assigned stack.
521 assert(Bundle.isFixed() && "Reached block before any predecessors");
522
523 // Push the fixed live-in registers.
524 for (unsigned i = Bundle.FixCount; i > 0; --i) {
525 LLVM_DEBUG(dbgs() << "Live-in st(" << (i - 1) << "): %fp"
526 << unsigned(Bundle.FixStack[i - 1]) << '\n');
527 pushReg(Bundle.FixStack[i-1]);
528 }
529
530 // Kill off unwanted live-ins. This can happen with a critical edge.
531 // FIXME: We could keep these live registers around as zombies. They may need
532 // to be revived at the end of a short block. It might save a few instrs.
533 unsigned Mask = calcLiveInMask(MBB, /*RemoveFPs=*/true);
534 adjustLiveRegs(Mask, MBB->begin());
535 LLVM_DEBUG(MBB->dump());
536 }
537
538 /// finishBlockStack - Revive live-outs that are implicitly defined out of
539 /// MBB. Shuffle live registers to match the expected fixed stack of any
540 /// predecessors, and ensure that all predecessors are expecting the same
541 /// stack.
542 void FPS::finishBlockStack() {
543 // The RET handling below takes care of return blocks for us.
544 if (MBB->succ_empty())
545 return;
546
547 LLVM_DEBUG(dbgs() << "Setting up live-outs for " << printMBBReference(*MBB)
548 << " derived from " << MBB->getName() << ".\n");
549
550 // Get MBB's live-out bundle.
551 unsigned BundleIdx = Bundles->getBundle(MBB->getNumber(), true);
552 LiveBundle &Bundle = LiveBundles[BundleIdx];
553
554 // We may need to kill and define some registers to match successors.
555 // FIXME: This can probably be combined with the shuffle below.
556 MachineBasicBlock::iterator Term = MBB->getFirstTerminator();
557 adjustLiveRegs(Bundle.Mask, Term);
558
559 if (!Bundle.Mask) {
560 LLVM_DEBUG(dbgs() << "No live-outs.\n");
561 return;
562 }
563
564 // Has the stack order been fixed yet?
565 LLVM_DEBUG(dbgs() << "LB#" << BundleIdx << ": ");
566 if (Bundle.isFixed()) {
567 LLVM_DEBUG(dbgs() << "Shuffling stack to match.\n");
568 shuffleStackTop(Bundle.FixStack, Bundle.FixCount, Term);
569 } else {
570 // Not fixed yet, we get to choose.
571 LLVM_DEBUG(dbgs() << "Fixing stack order now.\n");
572 Bundle.FixCount = StackTop;
573 for (unsigned i = 0; i < StackTop; ++i)
574 Bundle.FixStack[i] = getStackEntry(i);
575 }
576 }
577
578
579 //===----------------------------------------------------------------------===//
580 // Efficient Lookup Table Support
581 //===----------------------------------------------------------------------===//
582
583 namespace {
584 struct TableEntry {
585 uint16_t from;
586 uint16_t to;
587 bool operator<(const TableEntry &TE) const { return from < TE.from; }
588 friend bool operator<(const TableEntry &TE, unsigned V) {
589 return TE.from < V;
590 }
591 friend bool LLVM_ATTRIBUTE_UNUSED operator<(unsigned V,
592 const TableEntry &TE) {
593 return V < TE.from;
594 }
595 };
596 }
597
598 static int Lookup(ArrayRef<TableEntry> Table, unsigned Opcode) {
599 const TableEntry *I = llvm::lower_bound(Table, Opcode);
600 if (I != Table.end() && I->from == Opcode)
601 return I->to;
602 return -1;
603 }
604
605 #ifdef NDEBUG
606 #define ASSERT_SORTED(TABLE)
607 #else
608 #define ASSERT_SORTED(TABLE) \
609 { \
610 static std::atomic<bool> TABLE##Checked(false); \
611 if (!TABLE##Checked.load(std::memory_order_relaxed)) { \
612 assert(std::is_sorted(std::begin(TABLE), std::end(TABLE)) && \
613 "All lookup tables must be sorted for efficient access!"); \
614 TABLE##Checked.store(true, std::memory_order_relaxed); \
615 } \
616 }
617 #endif
618
619 //===----------------------------------------------------------------------===//
620 // Register File -> Register Stack Mapping Methods
621 //===----------------------------------------------------------------------===//
622
623 // OpcodeTable - Sorted map of register instructions to their stack version.
624 // The first element is an register file pseudo instruction, the second is the
625 // concrete X86 instruction which uses the register stack.
626 //
627 static const TableEntry OpcodeTable[] = {
628 { X86::ABS_Fp32 , X86::ABS_F },
629 { X86::ABS_Fp64 , X86::ABS_F },
630 { X86::ABS_Fp80 , X86::ABS_F },
631 { X86::ADD_Fp32m , X86::ADD_F32m },
632 { X86::ADD_Fp64m , X86::ADD_F64m },
633 { X86::ADD_Fp64m32 , X86::ADD_F32m },
634 { X86::ADD_Fp80m32 , X86::ADD_F32m },
635 { X86::ADD_Fp80m64 , X86::ADD_F64m },
636 { X86::ADD_FpI16m32 , X86::ADD_FI16m },
637 { X86::ADD_FpI16m64 , X86::ADD_FI16m },
638 { X86::ADD_FpI16m80 , X86::ADD_FI16m },
639 { X86::ADD_FpI32m32 , X86::ADD_FI32m },
640 { X86::ADD_FpI32m64 , X86::ADD_FI32m },
641 { X86::ADD_FpI32m80 , X86::ADD_FI32m },
642 { X86::CHS_Fp32 , X86::CHS_F },
643 { X86::CHS_Fp64 , X86::CHS_F },
644 { X86::CHS_Fp80 , X86::CHS_F },
645 { X86::CMOVBE_Fp32 , X86::CMOVBE_F },
646 { X86::CMOVBE_Fp64 , X86::CMOVBE_F },
647 { X86::CMOVBE_Fp80 , X86::CMOVBE_F },
648 { X86::CMOVB_Fp32 , X86::CMOVB_F },
649 { X86::CMOVB_Fp64 , X86::CMOVB_F },
650 { X86::CMOVB_Fp80 , X86::CMOVB_F },
651 { X86::CMOVE_Fp32 , X86::CMOVE_F },
652 { X86::CMOVE_Fp64 , X86::CMOVE_F },
653 { X86::CMOVE_Fp80 , X86::CMOVE_F },
654 { X86::CMOVNBE_Fp32 , X86::CMOVNBE_F },
655 { X86::CMOVNBE_Fp64 , X86::CMOVNBE_F },
656 { X86::CMOVNBE_Fp80 , X86::CMOVNBE_F },
657 { X86::CMOVNB_Fp32 , X86::CMOVNB_F },
658 { X86::CMOVNB_Fp64 , X86::CMOVNB_F },
659 { X86::CMOVNB_Fp80 , X86::CMOVNB_F },
660 { X86::CMOVNE_Fp32 , X86::CMOVNE_F },
661 { X86::CMOVNE_Fp64 , X86::CMOVNE_F },
662 { X86::CMOVNE_Fp80 , X86::CMOVNE_F },
663 { X86::CMOVNP_Fp32 , X86::CMOVNP_F },
664 { X86::CMOVNP_Fp64 , X86::CMOVNP_F },
665 { X86::CMOVNP_Fp80 , X86::CMOVNP_F },
666 { X86::CMOVP_Fp32 , X86::CMOVP_F },
667 { X86::CMOVP_Fp64 , X86::CMOVP_F },
668 { X86::CMOVP_Fp80 , X86::CMOVP_F },
669 { X86::COS_Fp32 , X86::COS_F },
670 { X86::COS_Fp64 , X86::COS_F },
671 { X86::COS_Fp80 , X86::COS_F },
672 { X86::DIVR_Fp32m , X86::DIVR_F32m },
673 { X86::DIVR_Fp64m , X86::DIVR_F64m },
674 { X86::DIVR_Fp64m32 , X86::DIVR_F32m },
675 { X86::DIVR_Fp80m32 , X86::DIVR_F32m },
676 { X86::DIVR_Fp80m64 , X86::DIVR_F64m },
677 { X86::DIVR_FpI16m32, X86::DIVR_FI16m},
678 { X86::DIVR_FpI16m64, X86::DIVR_FI16m},
679 { X86::DIVR_FpI16m80, X86::DIVR_FI16m},
680 { X86::DIVR_FpI32m32, X86::DIVR_FI32m},
681 { X86::DIVR_FpI32m64, X86::DIVR_FI32m},
682 { X86::DIVR_FpI32m80, X86::DIVR_FI32m},
683 { X86::DIV_Fp32m , X86::DIV_F32m },
684 { X86::DIV_Fp64m , X86::DIV_F64m },
685 { X86::DIV_Fp64m32 , X86::DIV_F32m },
686 { X86::DIV_Fp80m32 , X86::DIV_F32m },
687 { X86::DIV_Fp80m64 , X86::DIV_F64m },
688 { X86::DIV_FpI16m32 , X86::DIV_FI16m },
689 { X86::DIV_FpI16m64 , X86::DIV_FI16m },
690 { X86::DIV_FpI16m80 , X86::DIV_FI16m },
691 { X86::DIV_FpI32m32 , X86::DIV_FI32m },
692 { X86::DIV_FpI32m64 , X86::DIV_FI32m },
693 { X86::DIV_FpI32m80 , X86::DIV_FI32m },
694 { X86::ILD_Fp16m32 , X86::ILD_F16m },
695 { X86::ILD_Fp16m64 , X86::ILD_F16m },
696 { X86::ILD_Fp16m80 , X86::ILD_F16m },
697 { X86::ILD_Fp32m32 , X86::ILD_F32m },
698 { X86::ILD_Fp32m64 , X86::ILD_F32m },
699 { X86::ILD_Fp32m80 , X86::ILD_F32m },
700 { X86::ILD_Fp64m32 , X86::ILD_F64m },
701 { X86::ILD_Fp64m64 , X86::ILD_F64m },
702 { X86::ILD_Fp64m80 , X86::ILD_F64m },
703 { X86::ISTT_Fp16m32 , X86::ISTT_FP16m},
704 { X86::ISTT_Fp16m64 , X86::ISTT_FP16m},
705 { X86::ISTT_Fp16m80 , X86::ISTT_FP16m},
706 { X86::ISTT_Fp32m32 , X86::ISTT_FP32m},
707 { X86::ISTT_Fp32m64 , X86::ISTT_FP32m},
708 { X86::ISTT_Fp32m80 , X86::ISTT_FP32m},
709 { X86::ISTT_Fp64m32 , X86::ISTT_FP64m},
710 { X86::ISTT_Fp64m64 , X86::ISTT_FP64m},
711 { X86::ISTT_Fp64m80 , X86::ISTT_FP64m},
712 { X86::IST_Fp16m32 , X86::IST_F16m },
713 { X86::IST_Fp16m64 , X86::IST_F16m },
714 { X86::IST_Fp16m80 , X86::IST_F16m },
715 { X86::IST_Fp32m32 , X86::IST_F32m },
716 { X86::IST_Fp32m64 , X86::IST_F32m },
717 { X86::IST_Fp32m80 , X86::IST_F32m },
718 { X86::IST_Fp64m32 , X86::IST_FP64m },
719 { X86::IST_Fp64m64 , X86::IST_FP64m },
720 { X86::IST_Fp64m80 , X86::IST_FP64m },
721 { X86::LD_Fp032 , X86::LD_F0 },
722 { X86::LD_Fp064 , X86::LD_F0 },
723 { X86::LD_Fp080 , X86::LD_F0 },
724 { X86::LD_Fp132 , X86::LD_F1 },
725 { X86::LD_Fp164 , X86::LD_F1 },
726 { X86::LD_Fp180 , X86::LD_F1 },
727 { X86::LD_Fp32m , X86::LD_F32m },
728 { X86::LD_Fp32m64 , X86::LD_F32m },
729 { X86::LD_Fp32m80 , X86::LD_F32m },
730 { X86::LD_Fp64m , X86::LD_F64m },
731 { X86::LD_Fp64m80 , X86::LD_F64m },
732 { X86::LD_Fp80m , X86::LD_F80m },
733 { X86::MUL_Fp32m , X86::MUL_F32m },
734 { X86::MUL_Fp64m , X86::MUL_F64m },
735 { X86::MUL_Fp64m32 , X86::MUL_F32m },
736 { X86::MUL_Fp80m32 , X86::MUL_F32m },
737 { X86::MUL_Fp80m64 , X86::MUL_F64m },
738 { X86::MUL_FpI16m32 , X86::MUL_FI16m },
739 { X86::MUL_FpI16m64 , X86::MUL_FI16m },
740 { X86::MUL_FpI16m80 , X86::MUL_FI16m },
741 { X86::MUL_FpI32m32 , X86::MUL_FI32m },
742 { X86::MUL_FpI32m64 , X86::MUL_FI32m },
743 { X86::MUL_FpI32m80 , X86::MUL_FI32m },
744 { X86::SIN_Fp32 , X86::SIN_F },
745 { X86::SIN_Fp64 , X86::SIN_F },
746 { X86::SIN_Fp80 , X86::SIN_F },
747 { X86::SQRT_Fp32 , X86::SQRT_F },
748 { X86::SQRT_Fp64 , X86::SQRT_F },
749 { X86::SQRT_Fp80 , X86::SQRT_F },
750 { X86::ST_Fp32m , X86::ST_F32m },
751 { X86::ST_Fp64m , X86::ST_F64m },
752 { X86::ST_Fp64m32 , X86::ST_F32m },
753 { X86::ST_Fp80m32 , X86::ST_F32m },
754 { X86::ST_Fp80m64 , X86::ST_F64m },
755 { X86::ST_FpP80m , X86::ST_FP80m },
756 { X86::SUBR_Fp32m , X86::SUBR_F32m },
757 { X86::SUBR_Fp64m , X86::SUBR_F64m },
758 { X86::SUBR_Fp64m32 , X86::SUBR_F32m },
759 { X86::SUBR_Fp80m32 , X86::SUBR_F32m },
760 { X86::SUBR_Fp80m64 , X86::SUBR_F64m },
761 { X86::SUBR_FpI16m32, X86::SUBR_FI16m},
762 { X86::SUBR_FpI16m64, X86::SUBR_FI16m},
763 { X86::SUBR_FpI16m80, X86::SUBR_FI16m},
764 { X86::SUBR_FpI32m32, X86::SUBR_FI32m},
765 { X86::SUBR_FpI32m64, X86::SUBR_FI32m},
766 { X86::SUBR_FpI32m80, X86::SUBR_FI32m},
767 { X86::SUB_Fp32m , X86::SUB_F32m },
768 { X86::SUB_Fp64m , X86::SUB_F64m },
769 { X86::SUB_Fp64m32 , X86::SUB_F32m },
770 { X86::SUB_Fp80m32 , X86::SUB_F32m },
771 { X86::SUB_Fp80m64 , X86::SUB_F64m },
772 { X86::SUB_FpI16m32 , X86::SUB_FI16m },
773 { X86::SUB_FpI16m64 , X86::SUB_FI16m },
774 { X86::SUB_FpI16m80 , X86::SUB_FI16m },
775 { X86::SUB_FpI32m32 , X86::SUB_FI32m },
776 { X86::SUB_FpI32m64 , X86::SUB_FI32m },
777 { X86::SUB_FpI32m80 , X86::SUB_FI32m },
778 { X86::TST_Fp32 , X86::TST_F },
779 { X86::TST_Fp64 , X86::TST_F },
780 { X86::TST_Fp80 , X86::TST_F },
781 { X86::UCOM_FpIr32 , X86::UCOM_FIr },
782 { X86::UCOM_FpIr64 , X86::UCOM_FIr },
783 { X86::UCOM_FpIr80 , X86::UCOM_FIr },
784 { X86::UCOM_Fpr32 , X86::UCOM_Fr },
785 { X86::UCOM_Fpr64 , X86::UCOM_Fr },
786 { X86::UCOM_Fpr80 , X86::UCOM_Fr },
787 };
788
789 static unsigned getConcreteOpcode(unsigned Opcode) {
790 ASSERT_SORTED(OpcodeTable);
791 int Opc = Lookup(OpcodeTable, Opcode);
792 assert(Opc != -1 && "FP Stack instruction not in OpcodeTable!");
793 return Opc;
794 }
795
796 //===----------------------------------------------------------------------===//
797 // Helper Methods
798 //===----------------------------------------------------------------------===//
799
800 // PopTable - Sorted map of instructions to their popping version. The first
801 // element is an instruction, the second is the version which pops.
802 //
803 static const TableEntry PopTable[] = {
804 { X86::ADD_FrST0 , X86::ADD_FPrST0 },
805
806 { X86::DIVR_FrST0, X86::DIVR_FPrST0 },
807 { X86::DIV_FrST0 , X86::DIV_FPrST0 },
808
809 { X86::IST_F16m , X86::IST_FP16m },
810 { X86::IST_F32m , X86::IST_FP32m },
811
812 { X86::MUL_FrST0 , X86::MUL_FPrST0 },
813
814 { X86::ST_F32m , X86::ST_FP32m },
815 { X86::ST_F64m , X86::ST_FP64m },
816 { X86::ST_Frr , X86::ST_FPrr },
817
818 { X86::SUBR_FrST0, X86::SUBR_FPrST0 },
819 { X86::SUB_FrST0 , X86::SUB_FPrST0 },
820
821 { X86::UCOM_FIr , X86::UCOM_FIPr },
822
823 { X86::UCOM_FPr , X86::UCOM_FPPr },
824 { X86::UCOM_Fr , X86::UCOM_FPr },
825 };
826
827 /// popStackAfter - Pop the current value off of the top of the FP stack after
828 /// the specified instruction. This attempts to be sneaky and combine the pop
829 /// into the instruction itself if possible. The iterator is left pointing to
830 /// the last instruction, be it a new pop instruction inserted, or the old
831 /// instruction if it was modified in place.
832 ///
833 void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
834 MachineInstr &MI = *I;
835 const DebugLoc &dl = MI.getDebugLoc();
836 ASSERT_SORTED(PopTable);
837
838 popReg();
839
840 // Check to see if there is a popping version of this instruction...
841 int Opcode = Lookup(PopTable, I->getOpcode());
842 if (Opcode != -1) {
843 I->setDesc(TII->get(Opcode));
844 if (Opcode == X86::UCOM_FPPr)
845 I->RemoveOperand(0);
846 } else { // Insert an explicit pop
847 I = BuildMI(*MBB, ++I, dl, TII->get(X86::ST_FPrr)).addReg(X86::ST0);
848 }
849 }
850
851 /// freeStackSlotAfter - Free the specified register from the register stack, so
852 /// that it is no longer in a register. If the register is currently at the top
853 /// of the stack, we just pop the current instruction, otherwise we store the
854 /// current top-of-stack into the specified slot, then pop the top of stack.
855 void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
856 if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy.
857 popStackAfter(I);
858 return;
859 }
860
861 // Otherwise, store the top of stack into the dead slot, killing the operand
862 // without having to add in an explicit xchg then pop.
863 //
864 I = freeStackSlotBefore(++I, FPRegNo);
865 }
866
867 /// freeStackSlotBefore - Free the specified register without trying any
868 /// folding.
869 MachineBasicBlock::iterator
870 FPS::freeStackSlotBefore(MachineBasicBlock::iterator I, unsigned FPRegNo) {
871 unsigned STReg = getSTReg(FPRegNo);
872 unsigned OldSlot = getSlot(FPRegNo);
873 unsigned TopReg = Stack[StackTop-1];
874 Stack[OldSlot] = TopReg;
875 RegMap[TopReg] = OldSlot;
876 RegMap[FPRegNo] = ~0;
877 Stack[--StackTop] = ~0;
878 return BuildMI(*MBB, I, DebugLoc(), TII->get(X86::ST_FPrr))
879 .addReg(STReg)
880 .getInstr();
881 }
882
883 /// adjustLiveRegs - Kill and revive registers such that exactly the FP
884 /// registers with a bit in Mask are live.
885 void FPS::adjustLiveRegs(unsigned Mask, MachineBasicBlock::iterator I) {
886 unsigned Defs = Mask;
887 unsigned Kills = 0;
888 for (unsigned i = 0; i < StackTop; ++i) {
889 unsigned RegNo = Stack[i];
890 if (!(Defs & (1 << RegNo)))
891 // This register is live, but we don't want it.
892 Kills |= (1 << RegNo);
893 else
894 // We don't need to imp-def this live register.
895 Defs &= ~(1 << RegNo);
896 }
897 assert((Kills & Defs) == 0 && "Register needs killing and def'ing?");
898
899 // Produce implicit-defs for free by using killed registers.
900 while (Kills && Defs) {
901 unsigned KReg = countTrailingZeros(Kills);
902 unsigned DReg = countTrailingZeros(Defs);
903 LLVM_DEBUG(dbgs() << "Renaming %fp" << KReg << " as imp %fp" << DReg
904 << "\n");
905 std::swap(Stack[getSlot(KReg)], Stack[getSlot(DReg)]);
906 std::swap(RegMap[KReg], RegMap[DReg]);
907 Kills &= ~(1 << KReg);
908 Defs &= ~(1 << DReg);
909 }
910
911 // Kill registers by popping.
912 if (Kills && I != MBB->begin()) {
913 MachineBasicBlock::iterator I2 = std::prev(I);
914 while (StackTop) {
915 unsigned KReg = getStackEntry(0);
916 if (!(Kills & (1 << KReg)))
917 break;
918 LLVM_DEBUG(dbgs() << "Popping %fp" << KReg << "\n");
919 popStackAfter(I2);
920 Kills &= ~(1 << KReg);
921 }
922 }
923
924 // Manually kill the rest.
925 while (Kills) {
926 unsigned KReg = countTrailingZeros(Kills);
927 LLVM_DEBUG(dbgs() << "Killing %fp" << KReg << "\n");
928 freeStackSlotBefore(I, KReg);
929 Kills &= ~(1 << KReg);
930 }
931
932 // Load zeros for all the imp-defs.
933 while(Defs) {
934 unsigned DReg = countTrailingZeros(Defs);
935 LLVM_DEBUG(dbgs() << "Defining %fp" << DReg << " as 0\n");
936 BuildMI(*MBB, I, DebugLoc(), TII->get(X86::LD_F0));
937 pushReg(DReg);
938 Defs &= ~(1 << DReg);
939 }
940
941 // Now we should have the correct registers live.
942 LLVM_DEBUG(dumpStack());
943 assert(StackTop == countPopulation(Mask) && "Live count mismatch");
944 }
945
946 /// shuffleStackTop - emit fxch instructions before I to shuffle the top
947 /// FixCount entries into the order given by FixStack.
948 /// FIXME: Is there a better algorithm than insertion sort?
949 void FPS::shuffleStackTop(const unsigned char *FixStack,
950 unsigned FixCount,
951 MachineBasicBlock::iterator I) {
952 // Move items into place, starting from the desired stack bottom.
953 while (FixCount--) {
954 // Old register at position FixCount.
955 unsigned OldReg = getStackEntry(FixCount);
956 // Desired register at position FixCount.
957 unsigned Reg = FixStack[FixCount];
958 if (Reg == OldReg)
959 continue;
960 // (Reg st0) (OldReg st0) = (Reg OldReg st0)
961 moveToTop(Reg, I);
962 if (FixCount > 0)
963 moveToTop(OldReg, I);
964 }
965 LLVM_DEBUG(dumpStack());
966 }
967
968
969 //===----------------------------------------------------------------------===//
970 // Instruction transformation implementation
971 //===----------------------------------------------------------------------===//
972
973 void FPS::handleCall(MachineBasicBlock::iterator &I) {
974 unsigned STReturns = 0;
975 const MachineFunction* MF = I->getParent()->getParent();
976
977 for (const auto &MO : I->operands()) {
978 if (!MO.isReg())
979 continue;
980
981 unsigned R = MO.getReg() - X86::FP0;
982
983 if (R < 8) {
984 if (MF->getFunction().getCallingConv() != CallingConv::X86_RegCall) {
985 assert(MO.isDef() && MO.isImplicit());
986 }
987
988 STReturns |= 1 << R;
989 }
990 }
991
992 unsigned N = countTrailingOnes(STReturns);
993
994 // FP registers used for function return must be consecutive starting at
995 // FP0
996 assert(STReturns == 0 || (isMask_32(STReturns) && N <= 2));
997
998 // Reset the FP Stack - It is required because of possible leftovers from
999 // passed arguments. The caller should assume that the FP stack is
1000 // returned empty (unless the callee returns values on FP stack).
1001 while (StackTop > 0)
1002 popReg();
1003
1004 for (unsigned I = 0; I < N; ++I)
1005 pushReg(N - I - 1);
1006 }
1007
1008 /// If RET has an FP register use operand, pass the first one in ST(0) and
1009 /// the second one in ST(1).
1010 void FPS::handleReturn(MachineBasicBlock::iterator &I) {
1011 MachineInstr &MI = *I;
1012
1013 // Find the register operands.
1014 unsigned FirstFPRegOp = ~0U, SecondFPRegOp = ~0U;
1015 unsigned LiveMask = 0;
1016
1017 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
1018 MachineOperand &Op = MI.getOperand(i);
1019 if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
1020 continue;
1021 // FP Register uses must be kills unless there are two uses of the same
1022 // register, in which case only one will be a kill.
1023 assert(Op.isUse() &&
1024 (Op.isKill() || // Marked kill.
1025 getFPReg(Op) == FirstFPRegOp || // Second instance.
1026 MI.killsRegister(Op.getReg())) && // Later use is marked kill.
1027 "Ret only defs operands, and values aren't live beyond it");
1028
1029 if (FirstFPRegOp == ~0U)
1030 FirstFPRegOp = getFPReg(Op);
1031 else {
1032 assert(SecondFPRegOp == ~0U && "More than two fp operands!");
1033 SecondFPRegOp = getFPReg(Op);
1034 }
1035 LiveMask |= (1 << getFPReg(Op));
1036
1037 // Remove the operand so that later passes don't see it.
1038 MI.RemoveOperand(i);
1039 --i;
1040 --e;
1041 }
1042
1043 // We may have been carrying spurious live-ins, so make sure only the
1044 // returned registers are left live.
1045 adjustLiveRegs(LiveMask, MI);
1046 if (!LiveMask) return; // Quick check to see if any are possible.
1047
1048 // There are only four possibilities here:
1049 // 1) we are returning a single FP value. In this case, it has to be in
1050 // ST(0) already, so just declare success by removing the value from the
1051 // FP Stack.
1052 if (SecondFPRegOp == ~0U) {
1053 // Assert that the top of stack contains the right FP register.
1054 assert(StackTop == 1 && FirstFPRegOp == getStackEntry(0) &&
1055 "Top of stack not the right register for RET!");
1056
1057 // Ok, everything is good, mark the value as not being on the stack
1058 // anymore so that our assertion about the stack being empty at end of
1059 // block doesn't fire.
1060 StackTop = 0;
1061 return;
1062 }
1063
1064 // Otherwise, we are returning two values:
1065 // 2) If returning the same value for both, we only have one thing in the FP
1066 // stack. Consider: RET FP1, FP1
1067 if (StackTop == 1) {
1068 assert(FirstFPRegOp == SecondFPRegOp && FirstFPRegOp == getStackEntry(0)&&
1069 "Stack misconfiguration for RET!");
1070
1071 // Duplicate the TOS so that we return it twice. Just pick some other FPx
1072 // register to hold it.
1073 unsigned NewReg = ScratchFPReg;
1074 duplicateToTop(FirstFPRegOp, NewReg, MI);
1075 FirstFPRegOp = NewReg;
1076 }
1077
1078 /// Okay we know we have two different FPx operands now:
1079 assert(StackTop == 2 && "Must have two values live!");
1080
1081 /// 3) If SecondFPRegOp is currently in ST(0) and FirstFPRegOp is currently
1082 /// in ST(1). In this case, emit an fxch.
1083 if (getStackEntry(0) == SecondFPRegOp) {
1084 assert(getStackEntry(1) == FirstFPRegOp && "Unknown regs live");
1085 moveToTop(FirstFPRegOp, MI);
1086 }
1087
1088 /// 4) Finally, FirstFPRegOp must be in ST(0) and SecondFPRegOp must be in
1089 /// ST(1). Just remove both from our understanding of the stack and return.
1090 assert(getStackEntry(0) == FirstFPRegOp && "Unknown regs live");
1091 assert(getStackEntry(1) == SecondFPRegOp && "Unknown regs live");
1092 StackTop = 0;
1093 }
1094
1095 /// handleZeroArgFP - ST(0) = fld0 ST(0) = flds <mem>
1096 ///
1097 void FPS::handleZeroArgFP(MachineBasicBlock::iterator &I) {
1098 MachineInstr &MI = *I;
1099 unsigned DestReg = getFPReg(MI.getOperand(0));
1100
1101 // Change from the pseudo instruction to the concrete instruction.
1102 MI.RemoveOperand(0); // Remove the explicit ST(0) operand
1103 MI.setDesc(TII->get(getConcreteOpcode(MI.getOpcode())));
1104 MI.addOperand(
1105 MachineOperand::CreateReg(X86::ST0, /*isDef*/ true, /*isImp*/ true));
1106
1107 // Result gets pushed on the stack.
1108 pushReg(DestReg);
1109 }
1110
1111 /// handleOneArgFP - fst <mem>, ST(0)
1112 ///
1113 void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) {
1114 MachineInstr &MI = *I;
1115 unsigned NumOps = MI.getDesc().getNumOperands();
1116 assert((NumOps == X86::AddrNumOperands + 1 || NumOps == 1) &&
1117 "Can only handle fst* & ftst instructions!");
1118
1119 // Is this the last use of the source register?
1120 unsigned Reg = getFPReg(MI.getOperand(NumOps - 1));
1121 bool KillsSrc = MI.killsRegister(X86::FP0 + Reg);
1122
1123 // FISTP64m is strange because there isn't a non-popping versions.
1124 // If we have one _and_ we don't want to pop the operand, duplicate the value
1125 // on the stack instead of moving it. This ensure that popping the value is
1126 // always ok.
1127 // Ditto FISTTP16m, FISTTP32m, FISTTP64m, ST_FpP80m.
1128 //
1129 if (!KillsSrc && (MI.getOpcode() == X86::IST_Fp64m32 ||
1130 MI.getOpcode() == X86::ISTT_Fp16m32 ||
1131 MI.getOpcode() == X86::ISTT_Fp32m32 ||
1132 MI.getOpcode() == X86::ISTT_Fp64m32 ||
1133 MI.getOpcode() == X86::IST_Fp64m64 ||
1134 MI.getOpcode() == X86::ISTT_Fp16m64 ||
1135 MI.getOpcode() == X86::ISTT_Fp32m64 ||
1136 MI.getOpcode() == X86::ISTT_Fp64m64 ||
1137 MI.getOpcode() == X86::IST_Fp64m80 ||
1138 MI.getOpcode() == X86::ISTT_Fp16m80 ||
1139 MI.getOpcode() == X86::ISTT_Fp32m80 ||
1140 MI.getOpcode() == X86::ISTT_Fp64m80 ||
1141 MI.getOpcode() == X86::ST_FpP80m)) {
1142 duplicateToTop(Reg, ScratchFPReg, I);
1143 } else {
1144 moveToTop(Reg, I); // Move to the top of the stack...
1145 }
1146
1147 // Convert from the pseudo instruction to the concrete instruction.
1148 MI.RemoveOperand(NumOps - 1); // Remove explicit ST(0) operand
1149 MI.setDesc(TII->get(getConcreteOpcode(MI.getOpcode())));
1150 MI.addOperand(
1151 MachineOperand::CreateReg(X86::ST0, /*isDef*/ false, /*isImp*/ true));
1152
1153 if (MI.getOpcode() == X86::IST_FP64m || MI.getOpcode() == X86::ISTT_FP16m ||
1154 MI.getOpcode() == X86::ISTT_FP32m || MI.getOpcode() == X86::ISTT_FP64m ||
1155 MI.getOpcode() == X86::ST_FP80m) {
1156 if (StackTop == 0)
1157 report_fatal_error("Stack empty??");
1158 --StackTop;
1159 } else if (KillsSrc) { // Last use of operand?
1160 popStackAfter(I);
1161 }
1162 }
1163
1164
1165 /// handleOneArgFPRW: Handle instructions that read from the top of stack and
1166 /// replace the value with a newly computed value. These instructions may have
1167 /// non-fp operands after their FP operands.
1168 ///
1169 /// Examples:
1170 /// R1 = fchs R2
1171 /// R1 = fadd R2, [mem]
1172 ///
1173 void FPS::handleOneArgFPRW(MachineBasicBlock::iterator &I) {
1174 MachineInstr &MI = *I;
1175 #ifndef NDEBUG
1176 unsigned NumOps = MI.getDesc().getNumOperands();
1177 assert(NumOps >= 2 && "FPRW instructions must have 2 ops!!");
1178 #endif
1179
1180 // Is this the last use of the source register?
1181 unsigned Reg = getFPReg(MI.getOperand(1));
1182 bool KillsSrc = MI.killsRegister(X86::FP0 + Reg);
1183
1184 if (KillsSrc) {
1185 // If this is the last use of the source register, just make sure it's on
1186 // the top of the stack.
1187 moveToTop(Reg, I);
1188 if (StackTop == 0)
1189 report_fatal_error("Stack cannot be empty!");
1190 --StackTop;
1191 pushReg(getFPReg(MI.getOperand(0)));
1192 } else {
1193 // If this is not the last use of the source register, _copy_ it to the top
1194 // of the stack.
1195 duplicateToTop(Reg, getFPReg(MI.getOperand(0)), I);
1196 }
1197
1198 // Change from the pseudo instruction to the concrete instruction.
1199 MI.RemoveOperand(1); // Drop the source operand.
1200 MI.RemoveOperand(0); // Drop the destination operand.
1201 MI.setDesc(TII->get(getConcreteOpcode(MI.getOpcode())));
1202 }
1203
1204
1205 //===----------------------------------------------------------------------===//
1206 // Define tables of various ways to map pseudo instructions
1207 //
1208
1209 // ForwardST0Table - Map: A = B op C into: ST(0) = ST(0) op ST(i)
1210 static const TableEntry ForwardST0Table[] = {
1211 { X86::ADD_Fp32 , X86::ADD_FST0r },
1212 { X86::ADD_Fp64 , X86::ADD_FST0r },
1213 { X86::ADD_Fp80 , X86::ADD_FST0r },
1214 { X86::DIV_Fp32 , X86::DIV_FST0r },
1215 { X86::DIV_Fp64 , X86::DIV_FST0r },
1216 { X86::DIV_Fp80 , X86::DIV_FST0r },
1217 { X86::MUL_Fp32 , X86::MUL_FST0r },
1218 { X86::MUL_Fp64 , X86::MUL_FST0r },
1219 { X86::MUL_Fp80 , X86::MUL_FST0r },
1220 { X86::SUB_Fp32 , X86::SUB_FST0r },
1221 { X86::SUB_Fp64 , X86::SUB_FST0r },
1222 { X86::SUB_Fp80 , X86::SUB_FST0r },
1223 };
1224
1225 // ReverseST0Table - Map: A = B op C into: ST(0) = ST(i) op ST(0)
1226 static const TableEntry ReverseST0Table[] = {
1227 { X86::ADD_Fp32 , X86::ADD_FST0r }, // commutative
1228 { X86::ADD_Fp64 , X86::ADD_FST0r }, // commutative
1229 { X86::ADD_Fp80 , X86::ADD_FST0r }, // commutative
1230 { X86::DIV_Fp32 , X86::DIVR_FST0r },
1231 { X86::DIV_Fp64 , X86::DIVR_FST0r },
1232 { X86::DIV_Fp80 , X86::DIVR_FST0r },
1233 { X86::MUL_Fp32 , X86::MUL_FST0r }, // commutative
1234 { X86::MUL_Fp64 , X86::MUL_FST0r }, // commutative
1235 { X86::MUL_Fp80 , X86::MUL_FST0r }, // commutative
1236 { X86::SUB_Fp32 , X86::SUBR_FST0r },
1237 { X86::SUB_Fp64 , X86::SUBR_FST0r },
1238 { X86::SUB_Fp80 , X86::SUBR_FST0r },
1239 };
1240
1241 // ForwardSTiTable - Map: A = B op C into: ST(i) = ST(0) op ST(i)
1242 static const TableEntry ForwardSTiTable[] = {
1243 { X86::ADD_Fp32 , X86::ADD_FrST0 }, // commutative
1244 { X86::ADD_Fp64 , X86::ADD_FrST0 }, // commutative
1245 { X86::ADD_Fp80 , X86::ADD_FrST0 }, // commutative
1246 { X86::DIV_Fp32 , X86::DIVR_FrST0 },
1247 { X86::DIV_Fp64 , X86::DIVR_FrST0 },
1248 { X86::DIV_Fp80 , X86::DIVR_FrST0 },
1249 { X86::MUL_Fp32 , X86::MUL_FrST0 }, // commutative
1250 { X86::MUL_Fp64 , X86::MUL_FrST0 }, // commutative
1251 { X86::MUL_Fp80 , X86::MUL_FrST0 }, // commutative
1252 { X86::SUB_Fp32 , X86::SUBR_FrST0 },
1253 { X86::SUB_Fp64 , X86::SUBR_FrST0 },
1254 { X86::SUB_Fp80 , X86::SUBR_FrST0 },
1255 };
1256
1257 // ReverseSTiTable - Map: A = B op C into: ST(i) = ST(i) op ST(0)
1258 static const TableEntry ReverseSTiTable[] = {
1259 { X86::ADD_Fp32 , X86::ADD_FrST0 },
1260 { X86::ADD_Fp64 , X86::ADD_FrST0 },
1261 { X86::ADD_Fp80 , X86::ADD_FrST0 },
1262 { X86::DIV_Fp32 , X86::DIV_FrST0 },
1263 { X86::DIV_Fp64 , X86::DIV_FrST0 },
1264 { X86::DIV_Fp80 , X86::DIV_FrST0 },
1265 { X86::MUL_Fp32 , X86::MUL_FrST0 },
1266 { X86::MUL_Fp64 , X86::MUL_FrST0 },
1267 { X86::MUL_Fp80 , X86::MUL_FrST0 },
1268 { X86::SUB_Fp32 , X86::SUB_FrST0 },
1269 { X86::SUB_Fp64 , X86::SUB_FrST0 },
1270 { X86::SUB_Fp80 , X86::SUB_FrST0 },
1271 };
1272
1273
1274 /// handleTwoArgFP - Handle instructions like FADD and friends which are virtual
1275 /// instructions which need to be simplified and possibly transformed.
1276 ///
1277 /// Result: ST(0) = fsub ST(0), ST(i)
1278 /// ST(i) = fsub ST(0), ST(i)
1279 /// ST(0) = fsubr ST(0), ST(i)
1280 /// ST(i) = fsubr ST(0), ST(i)
1281 ///
1282 void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
1283 ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
1284 ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
1285 MachineInstr &MI = *I;
1286
1287 unsigned NumOperands = MI.getDesc().getNumOperands();
1288 assert(NumOperands == 3 && "Illegal TwoArgFP instruction!");
1289 unsigned Dest = getFPReg(MI.getOperand(0));
1290 unsigned Op0 = getFPReg(MI.getOperand(NumOperands - 2));
1291 unsigned Op1 = getFPReg(MI.getOperand(NumOperands - 1));
1292 bool KillsOp0 = MI.killsRegister(X86::FP0 + Op0);
1293 bool KillsOp1 = MI.killsRegister(X86::FP0 + Op1);
1294 DebugLoc dl = MI.getDebugLoc();
1295
1296 unsigned TOS = getStackEntry(0);
1297
1298 // One of our operands must be on the top of the stack. If neither is yet, we
1299 // need to move one.
1300 if (Op0 != TOS && Op1 != TOS) { // No operand at TOS?
1301 // We can choose to move either operand to the top of the stack. If one of
1302 // the operands is killed by this instruction, we want that one so that we
1303 // can update right on top of the old version.
1304 if (KillsOp0) {
1305 moveToTop(Op0, I); // Move dead operand to TOS.
1306 TOS = Op0;
1307 } else if (KillsOp1) {
1308 moveToTop(Op1, I);
1309 TOS = Op1;
1310 } else {
1311 // All of the operands are live after this instruction executes, so we
1312 // cannot update on top of any operand. Because of this, we must
1313 // duplicate one of the stack elements to the top. It doesn't matter
1314 // which one we pick.
1315 //
1316 duplicateToTop(Op0, Dest, I);
1317 Op0 = TOS = Dest;
1318 KillsOp0 = true;
1319 }
1320 } else if (!KillsOp0 && !KillsOp1) {
1321 // If we DO have one of our operands at the top of the stack, but we don't
1322 // have a dead operand, we must duplicate one of the operands to a new slot
1323 // on the stack.
1324 duplicateToTop(Op0, Dest, I);
1325 Op0 = TOS = Dest;
1326 KillsOp0 = true;
1327 }
1328
1329 // Now we know that one of our operands is on the top of the stack, and at
1330 // least one of our operands is killed by this instruction.
1331 assert((TOS == Op0 || TOS == Op1) && (KillsOp0 || KillsOp1) &&
1332 "Stack conditions not set up right!");
1333
1334 // We decide which form to use based on what is on the top of the stack, and
1335 // which operand is killed by this instruction.
1336 ArrayRef<TableEntry> InstTable;
1337 bool isForward = TOS == Op0;
1338 bool updateST0 = (TOS == Op0 && !KillsOp1) || (TOS == Op1 && !KillsOp0);
1339 if (updateST0) {
1340 if (isForward)
1341 InstTable = ForwardST0Table;
1342 else
1343 InstTable = ReverseST0Table;
1344 } else {
1345 if (isForward)
1346 InstTable = ForwardSTiTable;
1347 else
1348 InstTable = ReverseSTiTable;
1349 }
1350
1351 int Opcode = Lookup(InstTable, MI.getOpcode());
1352 assert(Opcode != -1 && "Unknown TwoArgFP pseudo instruction!");
1353
1354 // NotTOS - The register which is not on the top of stack...
1355 unsigned NotTOS = (TOS == Op0) ? Op1 : Op0;
1356
1357 // Replace the old instruction with a new instruction
1358 MBB->remove(&*I++);
1359 I = BuildMI(*MBB, I, dl, TII->get(Opcode)).addReg(getSTReg(NotTOS));
1360
1361 // If both operands are killed, pop one off of the stack in addition to
1362 // overwriting the other one.
1363 if (KillsOp0 && KillsOp1 && Op0 != Op1) {
1364 assert(!updateST0 && "Should have updated other operand!");
1365 popStackAfter(I); // Pop the top of stack
1366 }
1367
1368 // Update stack information so that we know the destination register is now on
1369 // the stack.
1370 unsigned UpdatedSlot = getSlot(updateST0 ? TOS : NotTOS);
1371 assert(UpdatedSlot < StackTop && Dest < 7);
1372 Stack[UpdatedSlot] = Dest;
1373 RegMap[Dest] = UpdatedSlot;
1374 MBB->getParent()->DeleteMachineInstr(&MI); // Remove the old instruction
1375 }
1376
1377 /// handleCompareFP - Handle FUCOM and FUCOMI instructions, which have two FP
1378 /// register arguments and no explicit destinations.
1379 ///
1380 void FPS::handleCompareFP(MachineBasicBlock::iterator &I) {
1381 MachineInstr &MI = *I;
1382
1383 unsigned NumOperands = MI.getDesc().getNumOperands();
1384 assert(NumOperands == 2 && "Illegal FUCOM* instruction!");
1385 unsigned Op0 = getFPReg(MI.getOperand(NumOperands - 2));
1386 unsigned Op1 = getFPReg(MI.getOperand(NumOperands - 1));
1387 bool KillsOp0 = MI.killsRegister(X86::FP0 + Op0);
1388 bool KillsOp1 = MI.killsRegister(X86::FP0 + Op1);
1389
1390 // Make sure the first operand is on the top of stack, the other one can be
1391 // anywhere.
1392 moveToTop(Op0, I);
1393
1394 // Change from the pseudo instruction to the concrete instruction.
1395 MI.getOperand(0).setReg(getSTReg(Op1));
1396 MI.RemoveOperand(1);
1397 MI.setDesc(TII->get(getConcreteOpcode(MI.getOpcode())));
1398
1399 // If any of the operands are killed by this instruction, free them.
1400 if (KillsOp0) freeStackSlotAfter(I, Op0);
1401 if (KillsOp1 && Op0 != Op1) freeStackSlotAfter(I, Op1);
1402 }
1403
1404 /// handleCondMovFP - Handle two address conditional move instructions. These
1405 /// instructions move a st(i) register to st(0) iff a condition is true. These
1406 /// instructions require that the first operand is at the top of the stack, but
1407 /// otherwise don't modify the stack at all.
1408 void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) {
1409 MachineInstr &MI = *I;
1410
1411 unsigned Op0 = getFPReg(MI.getOperand(0));
1412 unsigned Op1 = getFPReg(MI.getOperand(2));
1413 bool KillsOp1 = MI.killsRegister(X86::FP0 + Op1);
1414
1415 // The first operand *must* be on the top of the stack.
1416 moveToTop(Op0, I);
1417
1418 // Change the second operand to the stack register that the operand is in.
1419 // Change from the pseudo instruction to the concrete instruction.
1420 MI.RemoveOperand(0);
1421 MI.RemoveOperand(1);
1422 MI.getOperand(0).setReg(getSTReg(Op1));
1423 MI.setDesc(TII->get(getConcreteOpcode(MI.getOpcode())));
1424
1425 // If we kill the second operand, make sure to pop it from the stack.
1426 if (Op0 != Op1 && KillsOp1) {
1427 // Get this value off of the register stack.
1428 freeStackSlotAfter(I, Op1);
1429 }
1430 }
1431
1432
1433 /// handleSpecialFP - Handle special instructions which behave unlike other
1434 /// floating point instructions. This is primarily intended for use by pseudo
1435 /// instructions.
1436 ///
1437 void FPS::handleSpecialFP(MachineBasicBlock::iterator &Inst) {
1438 MachineInstr &MI = *Inst;
1439
1440 if (MI.isCall()) {
1441 handleCall(Inst);
1442 return;
1443 }
1444
1445 if (MI.isReturn()) {
1446 handleReturn(Inst);
1447 return;
1448 }
1449
1450 switch (MI.getOpcode()) {
1451 default: llvm_unreachable("Unknown SpecialFP instruction!");
1452 case TargetOpcode::COPY: {
1453 // We handle three kinds of copies: FP <- FP, FP <- ST, and ST <- FP.
1454 const MachineOperand &MO1 = MI.getOperand(1);
1455 const MachineOperand &MO0 = MI.getOperand(0);
1456 bool KillsSrc = MI.killsRegister(MO1.getReg());
1457
1458 // FP <- FP copy.
1459 unsigned DstFP = getFPReg(MO0);
1460 unsigned SrcFP = getFPReg(MO1);
1461 assert(isLive(SrcFP) && "Cannot copy dead register");
1462 if (KillsSrc) {
1463 // If the input operand is killed, we can just change the owner of the
1464 // incoming stack slot into the result.
1465 unsigned Slot = getSlot(SrcFP);
1466 Stack[Slot] = DstFP;
1467 RegMap[DstFP] = Slot;
1468 } else {
1469 // For COPY we just duplicate the specified value to a new stack slot.
1470 // This could be made better, but would require substantial changes.
1471 duplicateToTop(SrcFP, DstFP, Inst);
1472 }
1473 break;
1474 }
1475
1476 case TargetOpcode::IMPLICIT_DEF: {
1477 // All FP registers must be explicitly defined, so load a 0 instead.
1478 unsigned Reg = MI.getOperand(0).getReg() - X86::FP0;
1479 LLVM_DEBUG(dbgs() << "Emitting LD_F0 for implicit FP" << Reg << '\n');
1480 BuildMI(*MBB, Inst, MI.getDebugLoc(), TII->get(X86::LD_F0));
1481 pushReg(Reg);
1482 break;
1483 }
1484
1485 case TargetOpcode::INLINEASM:
1486 case TargetOpcode::INLINEASM_BR: {
1487 // The inline asm MachineInstr currently only *uses* FP registers for the
1488 // 'f' constraint. These should be turned into the current ST(x) register
1489 // in the machine instr.
1490 //
1491 // There are special rules for x87 inline assembly. The compiler must know
1492 // exactly how many registers are popped and pushed implicitly by the asm.
1493 // Otherwise it is not possible to restore the stack state after the inline
1494 // asm.
1495 //
1496 // There are 3 kinds of input operands:
1497 //
1498 // 1. Popped inputs. These must appear at the stack top in ST0-STn. A
1499 // popped input operand must be in a fixed stack slot, and it is either
1500 // tied to an output operand, or in the clobber list. The MI has ST use
1501 // and def operands for these inputs.
1502 //
1503 // 2. Fixed inputs. These inputs appear in fixed stack slots, but are
1504 // preserved by the inline asm. The fixed stack slots must be STn-STm
1505 // following the popped inputs. A fixed input operand cannot be tied to
1506 // an output or appear in the clobber list. The MI has ST use operands
1507 // and no defs for these inputs.
1508 //
1509 // 3. Preserved inputs. These inputs use the "f" constraint which is
1510 // represented as an FP register. The inline asm won't change these
1511 // stack slots.
1512 //
1513 // Outputs must be in ST registers, FP outputs are not allowed. Clobbered
1514 // registers do not count as output operands. The inline asm changes the
1515 // stack as if it popped all the popped inputs and then pushed all the
1516 // output operands.
1517
1518 // Scan the assembly for ST registers used, defined and clobbered. We can
1519 // only tell clobbers from defs by looking at the asm descriptor.
1520 unsigned STUses = 0, STDefs = 0, STClobbers = 0, STDeadDefs = 0;
1521 unsigned NumOps = 0;
1522 SmallSet<unsigned, 1> FRegIdx;
1523 unsigned RCID;
1524
1525 for (unsigned i = InlineAsm::MIOp_FirstOperand, e = MI.getNumOperands();
1526 i != e && MI.getOperand(i).isImm(); i += 1 + NumOps) {
1527 unsigned Flags = MI.getOperand(i).getImm();
1528
1529 NumOps = InlineAsm::getNumOperandRegisters(Flags);
1530 if (NumOps != 1)
1531 continue;
1532 const MachineOperand &MO = MI.getOperand(i + 1);
1533 if (!MO.isReg())
1534 continue;
1535 unsigned STReg = MO.getReg() - X86::FP0;
1536 if (STReg >= 8)
1537 continue;
1538
1539 // If the flag has a register class constraint, this must be an operand
1540 // with constraint "f". Record its index and continue.
1541 if (InlineAsm::hasRegClassConstraint(Flags, RCID)) {
1542 FRegIdx.insert(i + 1);
1543 continue;
1544 }
1545
1546 switch (InlineAsm::getKind(Flags)) {
1547 case InlineAsm::Kind_RegUse:
1548 STUses |= (1u << STReg);
1549 break;
1550 case InlineAsm::Kind_RegDef:
1551 case InlineAsm::Kind_RegDefEarlyClobber:
1552 STDefs |= (1u << STReg);
1553 if (MO.isDead())
1554 STDeadDefs |= (1u << STReg);
1555 break;
1556 case InlineAsm::Kind_Clobber:
1557 STClobbers |= (1u << STReg);
1558 break;
1559 default:
1560 break;
1561 }
1562 }
1563
1564 if (STUses && !isMask_32(STUses))
1565 MI.emitError("fixed input regs must be last on the x87 stack");
1566 unsigned NumSTUses = countTrailingOnes(STUses);
1567
1568 // Defs must be contiguous from the stack top. ST0-STn.
1569 if (STDefs && !isMask_32(STDefs)) {
1570 MI.emitError("output regs must be last on the x87 stack");
1571 STDefs = NextPowerOf2(STDefs) - 1;
1572 }
1573 unsigned NumSTDefs = countTrailingOnes(STDefs);
1574
1575 // So must the clobbered stack slots. ST0-STm, m >= n.
1576 if (STClobbers && !isMask_32(STDefs | STClobbers))
1577 MI.emitError("clobbers must be last on the x87 stack");
1578
1579 // Popped inputs are the ones that are also clobbered or defined.
1580 unsigned STPopped = STUses & (STDefs | STClobbers);
1581 if (STPopped && !isMask_32(STPopped))
1582 MI.emitError("implicitly popped regs must be last on the x87 stack");
1583 unsigned NumSTPopped = countTrailingOnes(STPopped);
1584
1585 LLVM_DEBUG(dbgs() << "Asm uses " << NumSTUses << " fixed regs, pops "
1586 << NumSTPopped << ", and defines " << NumSTDefs
1587 << " regs.\n");
1588
1589 #ifndef NDEBUG
1590 // If any input operand uses constraint "f", all output register
1591 // constraints must be early-clobber defs.
1592 for (unsigned I = 0, E = MI.getNumOperands(); I < E; ++I)
1593 if (FRegIdx.count(I)) {
1594 assert((1 << getFPReg(MI.getOperand(I)) & STDefs) == 0 &&
1595 "Operands with constraint \"f\" cannot overlap with defs");
1596 }
1597 #endif
1598
1599 // Collect all FP registers (register operands with constraints "t", "u",
1600 // and "f") to kill afer the instruction.
1601 unsigned FPKills = ((1u << NumFPRegs) - 1) & ~0xff;
1602 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
1603 MachineOperand &Op = MI.getOperand(i);
1604 if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
1605 continue;
1606 unsigned FPReg = getFPReg(Op);
1607
1608 // If we kill this operand, make sure to pop it from the stack after the
1609 // asm. We just remember it for now, and pop them all off at the end in
1610 // a batch.
1611 if (Op.isUse() && Op.isKill())
1612 FPKills |= 1U << FPReg;
1613 }
1614
1615 // Do not include registers that are implicitly popped by defs/clobbers.
1616 FPKills &= ~(STDefs | STClobbers);
1617
1618 // Now we can rearrange the live registers to match what was requested.
1619 unsigned char STUsesArray[8];
1620
1621 for (unsigned I = 0; I < NumSTUses; ++I)
1622 STUsesArray[I] = I;
1623
1624 shuffleStackTop(STUsesArray, NumSTUses, Inst);
1625 LLVM_DEBUG({
1626 dbgs() << "Before asm: ";
1627 dumpStack();
1628 });
1629
1630 // With the stack layout fixed, rewrite the FP registers.
1631 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
1632 MachineOperand &Op = MI.getOperand(i);
1633 if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
1634 continue;
1635
1636 unsigned FPReg = getFPReg(Op);
1637
1638 if (FRegIdx.count(i))
1639 // Operand with constraint "f".
1640 Op.setReg(getSTReg(FPReg));
1641 else
1642 // Operand with a single register class constraint ("t" or "u").
1643 Op.setReg(X86::ST0 + FPReg);
1644 }
1645
1646 // Simulate the inline asm popping its inputs and pushing its outputs.
1647 StackTop -= NumSTPopped;
1648
1649 for (unsigned i = 0; i < NumSTDefs; ++i)
1650 pushReg(NumSTDefs - i - 1);
1651
1652 // If this asm kills any FP registers (is the last use of them) we must
1653 // explicitly emit pop instructions for them. Do this now after the asm has
1654 // executed so that the ST(x) numbers are not off (which would happen if we
1655 // did this inline with operand rewriting).
1656 //
1657 // Note: this might be a non-optimal pop sequence. We might be able to do
1658 // better by trying to pop in stack order or something.
1659 while (FPKills) {
1660 unsigned FPReg = countTrailingZeros(FPKills);
1661 if (isLive(FPReg))
1662 freeStackSlotAfter(Inst, FPReg);
1663 FPKills &= ~(1U << FPReg);
1664 }
1665
1666 // Don't delete the inline asm!
1667 return;
1668 }
1669 }
1670
1671 Inst = MBB->erase(Inst); // Remove the pseudo instruction
1672
1673 // We want to leave I pointing to the previous instruction, but what if we
1674 // just erased the first instruction?
1675 if (Inst == MBB->begin()) {
1676 LLVM_DEBUG(dbgs() << "Inserting dummy KILL\n");
1677 Inst = BuildMI(*MBB, Inst, DebugLoc(), TII->get(TargetOpcode::KILL));
1678 } else
1679 --Inst;
1680 }
1681
1682 void FPS::setKillFlags(MachineBasicBlock &MBB) const {
1683 const TargetRegisterInfo &TRI =
1684 *MBB.getParent()->getSubtarget().getRegisterInfo();
1685 LivePhysRegs LPR(TRI);
1686
1687 LPR.addLiveOuts(MBB);
1688
1689 for (MachineBasicBlock::reverse_iterator I = MBB.rbegin(), E = MBB.rend();
1690 I != E; ++I) {
1691 if (I->isDebugInstr())
1692 continue;
1693
1694 std::bitset<8> Defs;
1695 SmallVector<MachineOperand *, 2> Uses;
1696 MachineInstr &MI = *I;
1697
1698 for (auto &MO : I->operands()) {
1699 if (!MO.isReg())
1700 continue;
1701
1702 unsigned Reg = MO.getReg() - X86::FP0;
1703
1704 if (Reg >= 8)
1705 continue;
1706
1707 if (MO.isDef()) {
1708 Defs.set(Reg);
1709 if (!LPR.contains(MO.getReg()))
1710 MO.setIsDead();
1711 } else
1712 Uses.push_back(&MO);
1713 }
1714
1715 for (auto *MO : Uses)
1716 if (Defs.test(getFPReg(*MO)) || !LPR.contains(MO->getReg()))
1717 MO->setIsKill();
1718
1719 LPR.stepBackward(MI);
1720 }
1721 }
The LLVM Project is a collection of modular and reusable compiler and toolchain technologies.