1 //===-- llvm/MC/MCInstrDesc.h - Instruction Descriptors -*- C++ -*-===//
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 defines the MCOperandInfo and MCInstrDesc classes, which
10 // are used to describe target instructions and their operands.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_MC_MCINSTRDESC_H
15 #define LLVM_MC_MCINSTRDESC_H
17 #include "llvm/MC/MCRegisterInfo.h"
18 #include "llvm/Support/DataTypes.h"
23 class MCSubtargetInfo
;
26 //===----------------------------------------------------------------------===//
27 // Machine Operand Flags and Description
28 //===----------------------------------------------------------------------===//
31 // Operand constraints
32 enum OperandConstraint
{
33 TIED_TO
= 0, // Must be allocated the same register as.
34 EARLY_CLOBBER
// Operand is an early clobber register operand
37 /// These are flags set on operands, but should be considered
38 /// private, all access should go through the MCOperandInfo accessors.
39 /// See the accessors for a description of what these are.
40 enum OperandFlags
{ LookupPtrRegClass
= 0, Predicate
, OptionalDef
};
42 /// Operands are tagged with one of the values of this enum.
45 OPERAND_IMMEDIATE
= 1,
50 OPERAND_FIRST_GENERIC
= 6,
51 OPERAND_GENERIC_0
= 6,
52 OPERAND_GENERIC_1
= 7,
53 OPERAND_GENERIC_2
= 8,
54 OPERAND_GENERIC_3
= 9,
55 OPERAND_GENERIC_4
= 10,
56 OPERAND_GENERIC_5
= 11,
57 OPERAND_LAST_GENERIC
= 11,
59 OPERAND_FIRST_GENERIC_IMM
= 12,
60 OPERAND_GENERIC_IMM_0
= 12,
61 OPERAND_LAST_GENERIC_IMM
= 12,
63 OPERAND_FIRST_TARGET
= 13,
68 /// This holds information about one operand of a machine instruction,
69 /// indicating the register class for register operands, etc.
72 /// This specifies the register class enumeration of the operand
73 /// if the operand is a register. If isLookupPtrRegClass is set, then this is
74 /// an index that is passed to TargetRegisterInfo::getPointerRegClass(x) to
75 /// get a dynamic register class.
78 /// These are flags from the MCOI::OperandFlags enum.
81 /// Information about the type of the operand.
83 /// The lower 16 bits are used to specify which constraints are set.
84 /// The higher 16 bits are used to specify the value of constraints (4 bits
88 /// Set if this operand is a pointer value and it requires a callback
89 /// to look up its register class.
90 bool isLookupPtrRegClass() const {
91 return Flags
& (1 << MCOI::LookupPtrRegClass
);
94 /// Set if this is one of the operands that made up of the predicate
95 /// operand that controls an isPredicable() instruction.
96 bool isPredicate() const { return Flags
& (1 << MCOI::Predicate
); }
98 /// Set if this operand is a optional def.
99 bool isOptionalDef() const { return Flags
& (1 << MCOI::OptionalDef
); }
101 bool isGenericType() const {
102 return OperandType
>= MCOI::OPERAND_FIRST_GENERIC
&&
103 OperandType
<= MCOI::OPERAND_LAST_GENERIC
;
106 unsigned getGenericTypeIndex() const {
107 assert(isGenericType() && "non-generic types don't have an index");
108 return OperandType
- MCOI::OPERAND_FIRST_GENERIC
;
111 bool isGenericImm() const {
112 return OperandType
>= MCOI::OPERAND_FIRST_GENERIC_IMM
&&
113 OperandType
<= MCOI::OPERAND_LAST_GENERIC_IMM
;
116 unsigned getGenericImmIndex() const {
117 assert(isGenericImm() && "non-generic immediates don't have an index");
118 return OperandType
- MCOI::OPERAND_FIRST_GENERIC_IMM
;
122 //===----------------------------------------------------------------------===//
123 // Machine Instruction Flags and Description
124 //===----------------------------------------------------------------------===//
127 /// These should be considered private to the implementation of the
128 /// MCInstrDesc class. Clients should use the predicate methods on MCInstrDesc,
129 /// not use these directly. These all correspond to bitfields in the
130 /// MCInstrDesc::Flags field.
155 UnmodeledSideEffects
,
174 /// Describe properties that are true of each instruction in the target
175 /// description file. This captures information about side effects, register
176 /// use and many other things. There is one instance of this struct for each
177 /// target instruction class, and the MachineInstr class points to this struct
178 /// directly to describe itself.
181 unsigned short Opcode
; // The opcode number
182 unsigned short NumOperands
; // Num of args (may be more if variable_ops)
183 unsigned char NumDefs
; // Num of args that are definitions
184 unsigned char Size
; // Number of bytes in encoding.
185 unsigned short SchedClass
; // enum identifying instr sched class
186 uint64_t Flags
; // Flags identifying machine instr class
187 uint64_t TSFlags
; // Target Specific Flag values
188 const MCPhysReg
*ImplicitUses
; // Registers implicitly read by this instr
189 const MCPhysReg
*ImplicitDefs
; // Registers implicitly defined by this instr
190 const MCOperandInfo
*OpInfo
; // 'NumOperands' entries about operands
191 // Subtarget feature that this is deprecated on, if any
192 // -1 implies this is not deprecated by any single feature. It may still be
193 // deprecated due to a "complex" reason, below.
194 int64_t DeprecatedFeature
;
196 // A complex method to determine if a certain instruction is deprecated or
197 // not, and return the reason for deprecation.
198 bool (*ComplexDeprecationInfo
)(MCInst
&, const MCSubtargetInfo
&,
201 /// Returns the value of the specific constraint if
202 /// it is set. Returns -1 if it is not set.
203 int getOperandConstraint(unsigned OpNum
,
204 MCOI::OperandConstraint Constraint
) const {
205 if (OpNum
< NumOperands
&&
206 (OpInfo
[OpNum
].Constraints
& (1 << Constraint
))) {
207 unsigned Pos
= 16 + Constraint
* 4;
208 return (int)(OpInfo
[OpNum
].Constraints
>> Pos
) & 0xf;
213 /// Returns true if a certain instruction is deprecated and if so
214 /// returns the reason in \p Info.
215 bool getDeprecatedInfo(MCInst
&MI
, const MCSubtargetInfo
&STI
,
216 std::string
&Info
) const;
218 /// Return the opcode number for this descriptor.
219 unsigned getOpcode() const { return Opcode
; }
221 /// Return the number of declared MachineOperands for this
222 /// MachineInstruction. Note that variadic (isVariadic() returns true)
223 /// instructions may have additional operands at the end of the list, and note
224 /// that the machine instruction may include implicit register def/uses as
226 unsigned getNumOperands() const { return NumOperands
; }
228 using const_opInfo_iterator
= const MCOperandInfo
*;
230 const_opInfo_iterator
opInfo_begin() const { return OpInfo
; }
231 const_opInfo_iterator
opInfo_end() const { return OpInfo
+ NumOperands
; }
233 iterator_range
<const_opInfo_iterator
> operands() const {
234 return make_range(opInfo_begin(), opInfo_end());
237 /// Return the number of MachineOperands that are register
238 /// definitions. Register definitions always occur at the start of the
239 /// machine operand list. This is the number of "outs" in the .td file,
240 /// and does not include implicit defs.
241 unsigned getNumDefs() const { return NumDefs
; }
243 /// Return flags of this instruction.
244 uint64_t getFlags() const { return Flags
; }
246 /// \returns true if this instruction is emitted before instruction selection
247 /// and should be legalized/regbankselected/selected.
248 bool isPreISelOpcode() const { return Flags
& (1ULL << MCID::PreISelOpcode
); }
250 /// Return true if this instruction can have a variable number of
251 /// operands. In this case, the variable operands will be after the normal
252 /// operands but before the implicit definitions and uses (if any are
254 bool isVariadic() const { return Flags
& (1ULL << MCID::Variadic
); }
256 /// Set if this instruction has an optional definition, e.g.
257 /// ARM instructions which can set condition code if 's' bit is set.
258 bool hasOptionalDef() const { return Flags
& (1ULL << MCID::HasOptionalDef
); }
260 /// Return true if this is a pseudo instruction that doesn't
261 /// correspond to a real machine instruction.
262 bool isPseudo() const { return Flags
& (1ULL << MCID::Pseudo
); }
264 /// Return true if the instruction is a return.
265 bool isReturn() const { return Flags
& (1ULL << MCID::Return
); }
267 /// Return true if the instruction is an add instruction.
268 bool isAdd() const { return Flags
& (1ULL << MCID::Add
); }
270 /// Return true if this instruction is a trap.
271 bool isTrap() const { return Flags
& (1ULL << MCID::Trap
); }
273 /// Return true if the instruction is a register to register move.
274 bool isMoveReg() const { return Flags
& (1ULL << MCID::MoveReg
); }
276 /// Return true if the instruction is a call.
277 bool isCall() const { return Flags
& (1ULL << MCID::Call
); }
279 /// Returns true if the specified instruction stops control flow
280 /// from executing the instruction immediately following it. Examples include
281 /// unconditional branches and return instructions.
282 bool isBarrier() const { return Flags
& (1ULL << MCID::Barrier
); }
284 /// Returns true if this instruction part of the terminator for
285 /// a basic block. Typically this is things like return and branch
288 /// Various passes use this to insert code into the bottom of a basic block,
289 /// but before control flow occurs.
290 bool isTerminator() const { return Flags
& (1ULL << MCID::Terminator
); }
292 /// Returns true if this is a conditional, unconditional, or
293 /// indirect branch. Predicates below can be used to discriminate between
294 /// these cases, and the TargetInstrInfo::AnalyzeBranch method can be used to
295 /// get more information.
296 bool isBranch() const { return Flags
& (1ULL << MCID::Branch
); }
298 /// Return true if this is an indirect branch, such as a
299 /// branch through a register.
300 bool isIndirectBranch() const { return Flags
& (1ULL << MCID::IndirectBranch
); }
302 /// Return true if this is a branch which may fall
303 /// through to the next instruction or may transfer control flow to some other
304 /// block. The TargetInstrInfo::AnalyzeBranch method can be used to get more
305 /// information about this branch.
306 bool isConditionalBranch() const {
307 return isBranch() & !isBarrier() & !isIndirectBranch();
310 /// Return true if this is a branch which always
311 /// transfers control flow to some other block. The
312 /// TargetInstrInfo::AnalyzeBranch method can be used to get more information
313 /// about this branch.
314 bool isUnconditionalBranch() const {
315 return isBranch() & isBarrier() & !isIndirectBranch();
318 /// Return true if this is a branch or an instruction which directly
319 /// writes to the program counter. Considered 'may' affect rather than
320 /// 'does' affect as things like predication are not taken into account.
321 bool mayAffectControlFlow(const MCInst
&MI
, const MCRegisterInfo
&RI
) const;
323 /// Return true if this instruction has a predicate operand
324 /// that controls execution. It may be set to 'always', or may be set to other
325 /// values. There are various methods in TargetInstrInfo that can be used to
326 /// control and modify the predicate in this instruction.
327 bool isPredicable() const { return Flags
& (1ULL << MCID::Predicable
); }
329 /// Return true if this instruction is a comparison.
330 bool isCompare() const { return Flags
& (1ULL << MCID::Compare
); }
332 /// Return true if this instruction is a move immediate
333 /// (including conditional moves) instruction.
334 bool isMoveImmediate() const { return Flags
& (1ULL << MCID::MoveImm
); }
336 /// Return true if this instruction is a bitcast instruction.
337 bool isBitcast() const { return Flags
& (1ULL << MCID::Bitcast
); }
339 /// Return true if this is a select instruction.
340 bool isSelect() const { return Flags
& (1ULL << MCID::Select
); }
342 /// Return true if this instruction cannot be safely
343 /// duplicated. For example, if the instruction has a unique labels attached
344 /// to it, duplicating it would cause multiple definition errors.
345 bool isNotDuplicable() const { return Flags
& (1ULL << MCID::NotDuplicable
); }
347 /// Returns true if the specified instruction has a delay slot which
348 /// must be filled by the code generator.
349 bool hasDelaySlot() const { return Flags
& (1ULL << MCID::DelaySlot
); }
351 /// Return true for instructions that can be folded as memory operands
352 /// in other instructions. The most common use for this is instructions that
353 /// are simple loads from memory that don't modify the loaded value in any
354 /// way, but it can also be used for instructions that can be expressed as
355 /// constant-pool loads, such as V_SETALLONES on x86, to allow them to be
356 /// folded when it is beneficial. This should only be set on instructions
357 /// that return a value in their only virtual register definition.
358 bool canFoldAsLoad() const { return Flags
& (1ULL << MCID::FoldableAsLoad
); }
360 /// Return true if this instruction behaves
361 /// the same way as the generic REG_SEQUENCE instructions.
363 /// dX VMOVDRR rY, rZ
365 /// dX = REG_SEQUENCE rY, ssub_0, rZ, ssub_1.
367 /// Note that for the optimizers to be able to take advantage of
368 /// this property, TargetInstrInfo::getRegSequenceLikeInputs has to be
369 /// override accordingly.
370 bool isRegSequenceLike() const { return Flags
& (1ULL << MCID::RegSequence
); }
372 /// Return true if this instruction behaves
373 /// the same way as the generic EXTRACT_SUBREG instructions.
375 /// rX, rY VMOVRRD dZ
376 /// is equivalent to two EXTRACT_SUBREG:
377 /// rX = EXTRACT_SUBREG dZ, ssub_0
378 /// rY = EXTRACT_SUBREG dZ, ssub_1
380 /// Note that for the optimizers to be able to take advantage of
381 /// this property, TargetInstrInfo::getExtractSubregLikeInputs has to be
382 /// override accordingly.
383 bool isExtractSubregLike() const {
384 return Flags
& (1ULL << MCID::ExtractSubreg
);
387 /// Return true if this instruction behaves
388 /// the same way as the generic INSERT_SUBREG instructions.
390 /// dX = VSETLNi32 dY, rZ, Imm
391 /// is equivalent to a INSERT_SUBREG:
392 /// dX = INSERT_SUBREG dY, rZ, translateImmToSubIdx(Imm)
394 /// Note that for the optimizers to be able to take advantage of
395 /// this property, TargetInstrInfo::getInsertSubregLikeInputs has to be
396 /// override accordingly.
397 bool isInsertSubregLike() const { return Flags
& (1ULL << MCID::InsertSubreg
); }
400 /// Return true if this instruction is convergent.
402 /// Convergent instructions may not be made control-dependent on any
403 /// additional values.
404 bool isConvergent() const { return Flags
& (1ULL << MCID::Convergent
); }
406 /// Return true if variadic operands of this instruction are definitions.
407 bool variadicOpsAreDefs() const {
408 return Flags
& (1ULL << MCID::VariadicOpsAreDefs
);
411 //===--------------------------------------------------------------------===//
412 // Side Effect Analysis
413 //===--------------------------------------------------------------------===//
415 /// Return true if this instruction could possibly read memory.
416 /// Instructions with this flag set are not necessarily simple load
417 /// instructions, they may load a value and modify it, for example.
418 bool mayLoad() const { return Flags
& (1ULL << MCID::MayLoad
); }
420 /// Return true if this instruction could possibly modify memory.
421 /// Instructions with this flag set are not necessarily simple store
422 /// instructions, they may store a modified value based on their operands, or
423 /// may not actually modify anything, for example.
424 bool mayStore() const { return Flags
& (1ULL << MCID::MayStore
); }
426 /// Return true if this instruction may raise a floating-point exception.
427 bool mayRaiseFPException() const {
428 return Flags
& (1ULL << MCID::MayRaiseFPException
);
431 /// Return true if this instruction has side
432 /// effects that are not modeled by other flags. This does not return true
433 /// for instructions whose effects are captured by:
435 /// 1. Their operand list and implicit definition/use list. Register use/def
436 /// info is explicit for instructions.
437 /// 2. Memory accesses. Use mayLoad/mayStore.
438 /// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
440 /// Examples of side effects would be modifying 'invisible' machine state like
441 /// a control register, flushing a cache, modifying a register invisible to
443 bool hasUnmodeledSideEffects() const {
444 return Flags
& (1ULL << MCID::UnmodeledSideEffects
);
447 //===--------------------------------------------------------------------===//
448 // Flags that indicate whether an instruction can be modified by a method.
449 //===--------------------------------------------------------------------===//
451 /// Return true if this may be a 2- or 3-address instruction (of the
452 /// form "X = op Y, Z, ..."), which produces the same result if Y and Z are
453 /// exchanged. If this flag is set, then the
454 /// TargetInstrInfo::commuteInstruction method may be used to hack on the
457 /// Note that this flag may be set on instructions that are only commutable
458 /// sometimes. In these cases, the call to commuteInstruction will fail.
459 /// Also note that some instructions require non-trivial modification to
461 bool isCommutable() const { return Flags
& (1ULL << MCID::Commutable
); }
463 /// Return true if this is a 2-address instruction which can be changed
464 /// into a 3-address instruction if needed. Doing this transformation can be
465 /// profitable in the register allocator, because it means that the
466 /// instruction can use a 2-address form if possible, but degrade into a less
467 /// efficient form if the source and dest register cannot be assigned to the
468 /// same register. For example, this allows the x86 backend to turn a "shl
469 /// reg, 3" instruction into an LEA instruction, which is the same speed as
470 /// the shift but has bigger code size.
472 /// If this returns true, then the target must implement the
473 /// TargetInstrInfo::convertToThreeAddress method for this instruction, which
474 /// is allowed to fail if the transformation isn't valid for this specific
475 /// instruction (e.g. shl reg, 4 on x86).
477 bool isConvertibleTo3Addr() const {
478 return Flags
& (1ULL << MCID::ConvertibleTo3Addr
);
481 /// Return true if this instruction requires custom insertion support
482 /// when the DAG scheduler is inserting it into a machine basic block. If
483 /// this is true for the instruction, it basically means that it is a pseudo
484 /// instruction used at SelectionDAG time that is expanded out into magic code
485 /// by the target when MachineInstrs are formed.
487 /// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
488 /// is used to insert this into the MachineBasicBlock.
489 bool usesCustomInsertionHook() const {
490 return Flags
& (1ULL << MCID::UsesCustomInserter
);
493 /// Return true if this instruction requires *adjustment* after
494 /// instruction selection by calling a target hook. For example, this can be
495 /// used to fill in ARM 's' optional operand depending on whether the
496 /// conditional flag register is used.
497 bool hasPostISelHook() const { return Flags
& (1ULL << MCID::HasPostISelHook
); }
499 /// Returns true if this instruction is a candidate for remat. This
500 /// flag is only used in TargetInstrInfo method isTriviallyRematerializable.
502 /// If this flag is set, the isReallyTriviallyReMaterializable()
503 /// or isReallyTriviallyReMaterializableGeneric methods are called to verify
504 /// the instruction is really rematable.
505 bool isRematerializable() const {
506 return Flags
& (1ULL << MCID::Rematerializable
);
509 /// Returns true if this instruction has the same cost (or less) than a
510 /// move instruction. This is useful during certain types of optimizations
511 /// (e.g., remat during two-address conversion or machine licm) where we would
512 /// like to remat or hoist the instruction, but not if it costs more than
513 /// moving the instruction into the appropriate register. Note, we are not
514 /// marking copies from and to the same register class with this flag.
516 /// This method could be called by interface TargetInstrInfo::isAsCheapAsAMove
517 /// for different subtargets.
518 bool isAsCheapAsAMove() const { return Flags
& (1ULL << MCID::CheapAsAMove
); }
520 /// Returns true if this instruction source operands have special
521 /// register allocation requirements that are not captured by the operand
522 /// register classes. e.g. ARM::STRD's two source registers must be an even /
523 /// odd pair, ARM::STM registers have to be in ascending order. Post-register
524 /// allocation passes should not attempt to change allocations for sources of
525 /// instructions with this flag.
526 bool hasExtraSrcRegAllocReq() const {
527 return Flags
& (1ULL << MCID::ExtraSrcRegAllocReq
);
530 /// Returns true if this instruction def operands have special register
531 /// allocation requirements that are not captured by the operand register
532 /// classes. e.g. ARM::LDRD's two def registers must be an even / odd pair,
533 /// ARM::LDM registers have to be in ascending order. Post-register
534 /// allocation passes should not attempt to change allocations for definitions
535 /// of instructions with this flag.
536 bool hasExtraDefRegAllocReq() const {
537 return Flags
& (1ULL << MCID::ExtraDefRegAllocReq
);
540 /// Return a list of registers that are potentially read by any
541 /// instance of this machine instruction. For example, on X86, the "adc"
542 /// instruction adds two register operands and adds the carry bit in from the
543 /// flags register. In this case, the instruction is marked as implicitly
544 /// reading the flags. Likewise, the variable shift instruction on X86 is
545 /// marked as implicitly reading the 'CL' register, which it always does.
547 /// This method returns null if the instruction has no implicit uses.
548 const MCPhysReg
*getImplicitUses() const { return ImplicitUses
; }
550 /// Return the number of implicit uses this instruction has.
551 unsigned getNumImplicitUses() const {
555 for (; ImplicitUses
[i
]; ++i
) /*empty*/
560 /// Return a list of registers that are potentially written by any
561 /// instance of this machine instruction. For example, on X86, many
562 /// instructions implicitly set the flags register. In this case, they are
563 /// marked as setting the FLAGS. Likewise, many instructions always deposit
564 /// their result in a physical register. For example, the X86 divide
565 /// instruction always deposits the quotient and remainder in the EAX/EDX
566 /// registers. For that instruction, this will return a list containing the
567 /// EAX/EDX/EFLAGS registers.
569 /// This method returns null if the instruction has no implicit defs.
570 const MCPhysReg
*getImplicitDefs() const { return ImplicitDefs
; }
572 /// Return the number of implicit defs this instruct has.
573 unsigned getNumImplicitDefs() const {
577 for (; ImplicitDefs
[i
]; ++i
) /*empty*/
582 /// Return true if this instruction implicitly
583 /// uses the specified physical register.
584 bool hasImplicitUseOfPhysReg(unsigned Reg
) const {
585 if (const MCPhysReg
*ImpUses
= ImplicitUses
)
586 for (; *ImpUses
; ++ImpUses
)
592 /// Return true if this instruction implicitly
593 /// defines the specified physical register.
594 bool hasImplicitDefOfPhysReg(unsigned Reg
,
595 const MCRegisterInfo
*MRI
= nullptr) const;
597 /// Return the scheduling class for this instruction. The
598 /// scheduling class is an index into the InstrItineraryData table. This
599 /// returns zero if there is no known scheduling information for the
601 unsigned getSchedClass() const { return SchedClass
; }
603 /// Return the number of bytes in the encoding of this instruction,
604 /// or zero if the encoding size cannot be known from the opcode.
605 unsigned getSize() const { return Size
; }
607 /// Find the index of the first operand in the
608 /// operand list that is used to represent the predicate. It returns -1 if
610 int findFirstPredOperandIdx() const {
611 if (isPredicable()) {
612 for (unsigned i
= 0, e
= getNumOperands(); i
!= e
; ++i
)
613 if (OpInfo
[i
].isPredicate())
619 /// Return true if this instruction defines the specified physical
620 /// register, either explicitly or implicitly.
621 bool hasDefOfPhysReg(const MCInst
&MI
, unsigned Reg
,
622 const MCRegisterInfo
&RI
) const;
625 } // end namespace llvm