1 //===-- llvm/MC/MCInstrDesc.h - Instruction Descriptors -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the MCOperandInfo and MCInstrDesc classes, which
11 // are used to describe target instructions and their operands.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_MC_MCINSTRDESC_H
16 #define LLVM_MC_MCINSTRDESC_H
18 #include "llvm/MC/MCRegisterInfo.h"
19 #include "llvm/Support/DataTypes.h"
24 class MCSubtargetInfo;
27 //===----------------------------------------------------------------------===//
28 // Machine Operand Flags and Description
29 //===----------------------------------------------------------------------===//
32 // Operand constraints
33 enum OperandConstraint {
34 TIED_TO = 0, // Must be allocated the same register as.
35 EARLY_CLOBBER // Operand is an early clobber register operand
38 /// \brief These are flags set on operands, but should be considered
39 /// private, all access should go through the MCOperandInfo accessors.
40 /// See the accessors for a description of what these are.
41 enum OperandFlags { LookupPtrRegClass = 0, Predicate, OptionalDef };
43 /// \brief Operands are tagged with one of the values of this enum.
46 OPERAND_IMMEDIATE = 1,
51 OPERAND_FIRST_GENERIC = 6,
52 OPERAND_GENERIC_0 = 6,
53 OPERAND_GENERIC_1 = 7,
54 OPERAND_GENERIC_2 = 8,
55 OPERAND_GENERIC_3 = 9,
56 OPERAND_GENERIC_4 = 10,
57 OPERAND_GENERIC_5 = 11,
58 OPERAND_LAST_GENERIC = 11,
60 OPERAND_FIRST_TARGET = 12,
63 enum GenericOperandType {
68 /// \brief This holds information about one operand of a machine instruction,
69 /// indicating the register class for register operands, etc.
72 /// \brief 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 /// \brief These are flags from the MCOI::OperandFlags enum.
81 /// \brief Information about the type of the operand.
83 /// \brief 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 /// \brief 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 /// \brief 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 /// \brief 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;
112 //===----------------------------------------------------------------------===//
113 // Machine Instruction Flags and Description
114 //===----------------------------------------------------------------------===//
117 /// \brief These should be considered private to the implementation of the
118 /// MCInstrDesc class. Clients should use the predicate methods on MCInstrDesc,
119 /// not use these directly. These all correspond to bitfields in the
120 /// MCInstrDesc::Flags field.
141 UnmodeledSideEffects,
158 /// \brief Describe properties that are true of each instruction in the target
159 /// description file. This captures information about side effects, register
160 /// use and many other things. There is one instance of this struct for each
161 /// target instruction class, and the MachineInstr class points to this struct
162 /// directly to describe itself.
165 unsigned short Opcode; // The opcode number
166 unsigned short NumOperands; // Num of args (may be more if variable_ops)
167 unsigned char NumDefs; // Num of args that are definitions
168 unsigned char Size; // Number of bytes in encoding.
169 unsigned short SchedClass; // enum identifying instr sched class
170 uint64_t Flags; // Flags identifying machine instr class
171 uint64_t TSFlags; // Target Specific Flag values
172 const MCPhysReg *ImplicitUses; // Registers implicitly read by this instr
173 const MCPhysReg *ImplicitDefs; // Registers implicitly defined by this instr
174 const MCOperandInfo *OpInfo; // 'NumOperands' entries about operands
175 // Subtarget feature that this is deprecated on, if any
176 // -1 implies this is not deprecated by any single feature. It may still be
177 // deprecated due to a "complex" reason, below.
178 int64_t DeprecatedFeature;
180 // A complex method to determine is a certain is deprecated or not, and return
181 // the reason for deprecation.
182 bool (*ComplexDeprecationInfo)(MCInst &, const MCSubtargetInfo &,
185 /// \brief Returns the value of the specific constraint if
186 /// it is set. Returns -1 if it is not set.
187 int getOperandConstraint(unsigned OpNum,
188 MCOI::OperandConstraint Constraint) const {
189 if (OpNum < NumOperands &&
190 (OpInfo[OpNum].Constraints & (1 << Constraint))) {
191 unsigned Pos = 16 + Constraint * 4;
192 return (int)(OpInfo[OpNum].Constraints >> Pos) & 0xf;
197 /// \brief Returns true if a certain instruction is deprecated and if so
198 /// returns the reason in \p Info.
199 bool getDeprecatedInfo(MCInst &MI, const MCSubtargetInfo &STI,
200 std::string &Info) const;
202 /// \brief Return the opcode number for this descriptor.
203 unsigned getOpcode() const { return Opcode; }
205 /// \brief Return the number of declared MachineOperands for this
206 /// MachineInstruction. Note that variadic (isVariadic() returns true)
207 /// instructions may have additional operands at the end of the list, and note
208 /// that the machine instruction may include implicit register def/uses as
210 unsigned getNumOperands() const { return NumOperands; }
212 using const_opInfo_iterator = const MCOperandInfo *;
214 const_opInfo_iterator opInfo_begin() const { return OpInfo; }
215 const_opInfo_iterator opInfo_end() const { return OpInfo + NumOperands; }
217 iterator_range<const_opInfo_iterator> operands() const {
218 return make_range(opInfo_begin(), opInfo_end());
221 /// \brief Return the number of MachineOperands that are register
222 /// definitions. Register definitions always occur at the start of the
223 /// machine operand list. This is the number of "outs" in the .td file,
224 /// and does not include implicit defs.
225 unsigned getNumDefs() const { return NumDefs; }
227 /// \brief Return flags of this instruction.
228 uint64_t getFlags() const { return Flags; }
230 /// \brief Return true if this instruction can have a variable number of
231 /// operands. In this case, the variable operands will be after the normal
232 /// operands but before the implicit definitions and uses (if any are
234 bool isVariadic() const { return Flags & (1ULL << MCID::Variadic); }
236 /// \brief Set if this instruction has an optional definition, e.g.
237 /// ARM instructions which can set condition code if 's' bit is set.
238 bool hasOptionalDef() const { return Flags & (1ULL << MCID::HasOptionalDef); }
240 /// \brief Return true if this is a pseudo instruction that doesn't
241 /// correspond to a real machine instruction.
242 bool isPseudo() const { return Flags & (1ULL << MCID::Pseudo); }
244 /// \brief Return true if the instruction is a return.
245 bool isReturn() const { return Flags & (1ULL << MCID::Return); }
247 /// \brief Return true if the instruction is an add instruction.
248 bool isAdd() const { return Flags & (1ULL << MCID::Add); }
250 /// \brief Return true if the instruction is a call.
251 bool isCall() const { return Flags & (1ULL << MCID::Call); }
253 /// \brief Returns true if the specified instruction stops control flow
254 /// from executing the instruction immediately following it. Examples include
255 /// unconditional branches and return instructions.
256 bool isBarrier() const { return Flags & (1ULL << MCID::Barrier); }
258 /// \brief Returns true if this instruction part of the terminator for
259 /// a basic block. Typically this is things like return and branch
262 /// Various passes use this to insert code into the bottom of a basic block,
263 /// but before control flow occurs.
264 bool isTerminator() const { return Flags & (1ULL << MCID::Terminator); }
266 /// \brief Returns true if this is a conditional, unconditional, or
267 /// indirect branch. Predicates below can be used to discriminate between
268 /// these cases, and the TargetInstrInfo::AnalyzeBranch method can be used to
269 /// get more information.
270 bool isBranch() const { return Flags & (1ULL << MCID::Branch); }
272 /// \brief Return true if this is an indirect branch, such as a
273 /// branch through a register.
274 bool isIndirectBranch() const { return Flags & (1ULL << MCID::IndirectBranch); }
276 /// \brief Return true if this is a branch which may fall
277 /// through to the next instruction or may transfer control flow to some other
278 /// block. The TargetInstrInfo::AnalyzeBranch method can be used to get more
279 /// information about this branch.
280 bool isConditionalBranch() const {
281 return isBranch() & !isBarrier() & !isIndirectBranch();
284 /// \brief Return true if this is a branch which always
285 /// transfers control flow to some other block. The
286 /// TargetInstrInfo::AnalyzeBranch method can be used to get more information
287 /// about this branch.
288 bool isUnconditionalBranch() const {
289 return isBranch() & isBarrier() & !isIndirectBranch();
292 /// \brief Return true if this is a branch or an instruction which directly
293 /// writes to the program counter. Considered 'may' affect rather than
294 /// 'does' affect as things like predication are not taken into account.
295 bool mayAffectControlFlow(const MCInst &MI, const MCRegisterInfo &RI) const;
297 /// \brief Return true if this instruction has a predicate operand
298 /// that controls execution. It may be set to 'always', or may be set to other
299 /// values. There are various methods in TargetInstrInfo that can be used to
300 /// control and modify the predicate in this instruction.
301 bool isPredicable() const { return Flags & (1ULL << MCID::Predicable); }
303 /// \brief Return true if this instruction is a comparison.
304 bool isCompare() const { return Flags & (1ULL << MCID::Compare); }
306 /// \brief Return true if this instruction is a move immediate
307 /// (including conditional moves) instruction.
308 bool isMoveImmediate() const { return Flags & (1ULL << MCID::MoveImm); }
310 /// \brief Return true if this instruction is a bitcast instruction.
311 bool isBitcast() const { return Flags & (1ULL << MCID::Bitcast); }
313 /// \brief Return true if this is a select instruction.
314 bool isSelect() const { return Flags & (1ULL << MCID::Select); }
316 /// \brief Return true if this instruction cannot be safely
317 /// duplicated. For example, if the instruction has a unique labels attached
318 /// to it, duplicating it would cause multiple definition errors.
319 bool isNotDuplicable() const { return Flags & (1ULL << MCID::NotDuplicable); }
321 /// \brief Returns true if the specified instruction has a delay slot which
322 /// must be filled by the code generator.
323 bool hasDelaySlot() const { return Flags & (1ULL << MCID::DelaySlot); }
325 /// \brief Return true for instructions that can be folded as memory operands
326 /// in other instructions. The most common use for this is instructions that
327 /// are simple loads from memory that don't modify the loaded value in any
328 /// way, but it can also be used for instructions that can be expressed as
329 /// constant-pool loads, such as V_SETALLONES on x86, to allow them to be
330 /// folded when it is beneficial. This should only be set on instructions
331 /// that return a value in their only virtual register definition.
332 bool canFoldAsLoad() const { return Flags & (1ULL << MCID::FoldableAsLoad); }
334 /// \brief Return true if this instruction behaves
335 /// the same way as the generic REG_SEQUENCE instructions.
337 /// dX VMOVDRR rY, rZ
339 /// dX = REG_SEQUENCE rY, ssub_0, rZ, ssub_1.
341 /// Note that for the optimizers to be able to take advantage of
342 /// this property, TargetInstrInfo::getRegSequenceLikeInputs has to be
343 /// override accordingly.
344 bool isRegSequenceLike() const { return Flags & (1ULL << MCID::RegSequence); }
346 /// \brief Return true if this instruction behaves
347 /// the same way as the generic EXTRACT_SUBREG instructions.
349 /// rX, rY VMOVRRD dZ
350 /// is equivalent to two EXTRACT_SUBREG:
351 /// rX = EXTRACT_SUBREG dZ, ssub_0
352 /// rY = EXTRACT_SUBREG dZ, ssub_1
354 /// Note that for the optimizers to be able to take advantage of
355 /// this property, TargetInstrInfo::getExtractSubregLikeInputs has to be
356 /// override accordingly.
357 bool isExtractSubregLike() const {
358 return Flags & (1ULL << MCID::ExtractSubreg);
361 /// \brief Return true if this instruction behaves
362 /// the same way as the generic INSERT_SUBREG instructions.
364 /// dX = VSETLNi32 dY, rZ, Imm
365 /// is equivalent to a INSERT_SUBREG:
366 /// dX = INSERT_SUBREG dY, rZ, translateImmToSubIdx(Imm)
368 /// Note that for the optimizers to be able to take advantage of
369 /// this property, TargetInstrInfo::getInsertSubregLikeInputs has to be
370 /// override accordingly.
371 bool isInsertSubregLike() const { return Flags & (1ULL << MCID::InsertSubreg); }
374 /// \brief Return true if this instruction is convergent.
376 /// Convergent instructions may not be made control-dependent on any
377 /// additional values.
378 bool isConvergent() const { return Flags & (1ULL << MCID::Convergent); }
380 //===--------------------------------------------------------------------===//
381 // Side Effect Analysis
382 //===--------------------------------------------------------------------===//
384 /// \brief Return true if this instruction could possibly read memory.
385 /// Instructions with this flag set are not necessarily simple load
386 /// instructions, they may load a value and modify it, for example.
387 bool mayLoad() const { return Flags & (1ULL << MCID::MayLoad); }
389 /// \brief Return true if this instruction could possibly modify memory.
390 /// Instructions with this flag set are not necessarily simple store
391 /// instructions, they may store a modified value based on their operands, or
392 /// may not actually modify anything, for example.
393 bool mayStore() const { return Flags & (1ULL << MCID::MayStore); }
395 /// \brief Return true if this instruction has side
396 /// effects that are not modeled by other flags. This does not return true
397 /// for instructions whose effects are captured by:
399 /// 1. Their operand list and implicit definition/use list. Register use/def
400 /// info is explicit for instructions.
401 /// 2. Memory accesses. Use mayLoad/mayStore.
402 /// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
404 /// Examples of side effects would be modifying 'invisible' machine state like
405 /// a control register, flushing a cache, modifying a register invisible to
407 bool hasUnmodeledSideEffects() const {
408 return Flags & (1ULL << MCID::UnmodeledSideEffects);
411 //===--------------------------------------------------------------------===//
412 // Flags that indicate whether an instruction can be modified by a method.
413 //===--------------------------------------------------------------------===//
415 /// \brief Return true if this may be a 2- or 3-address instruction (of the
416 /// form "X = op Y, Z, ..."), which produces the same result if Y and Z are
417 /// exchanged. If this flag is set, then the
418 /// TargetInstrInfo::commuteInstruction method may be used to hack on the
421 /// Note that this flag may be set on instructions that are only commutable
422 /// sometimes. In these cases, the call to commuteInstruction will fail.
423 /// Also note that some instructions require non-trivial modification to
425 bool isCommutable() const { return Flags & (1ULL << MCID::Commutable); }
427 /// \brief Return true if this is a 2-address instruction which can be changed
428 /// into a 3-address instruction if needed. Doing this transformation can be
429 /// profitable in the register allocator, because it means that the
430 /// instruction can use a 2-address form if possible, but degrade into a less
431 /// efficient form if the source and dest register cannot be assigned to the
432 /// same register. For example, this allows the x86 backend to turn a "shl
433 /// reg, 3" instruction into an LEA instruction, which is the same speed as
434 /// the shift but has bigger code size.
436 /// If this returns true, then the target must implement the
437 /// TargetInstrInfo::convertToThreeAddress method for this instruction, which
438 /// is allowed to fail if the transformation isn't valid for this specific
439 /// instruction (e.g. shl reg, 4 on x86).
441 bool isConvertibleTo3Addr() const {
442 return Flags & (1ULL << MCID::ConvertibleTo3Addr);
445 /// \brief Return true if this instruction requires custom insertion support
446 /// when the DAG scheduler is inserting it into a machine basic block. If
447 /// this is true for the instruction, it basically means that it is a pseudo
448 /// instruction used at SelectionDAG time that is expanded out into magic code
449 /// by the target when MachineInstrs are formed.
451 /// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
452 /// is used to insert this into the MachineBasicBlock.
453 bool usesCustomInsertionHook() const {
454 return Flags & (1ULL << MCID::UsesCustomInserter);
457 /// \brief Return true if this instruction requires *adjustment* after
458 /// instruction selection by calling a target hook. For example, this can be
459 /// used to fill in ARM 's' optional operand depending on whether the
460 /// conditional flag register is used.
461 bool hasPostISelHook() const { return Flags & (1ULL << MCID::HasPostISelHook); }
463 /// \brief Returns true if this instruction is a candidate for remat. This
464 /// flag is only used in TargetInstrInfo method isTriviallyRematerializable.
466 /// If this flag is set, the isReallyTriviallyReMaterializable()
467 /// or isReallyTriviallyReMaterializableGeneric methods are called to verify
468 /// the instruction is really rematable.
469 bool isRematerializable() const {
470 return Flags & (1ULL << MCID::Rematerializable);
473 /// \brief Returns true if this instruction has the same cost (or less) than a
474 /// move instruction. This is useful during certain types of optimizations
475 /// (e.g., remat during two-address conversion or machine licm) where we would
476 /// like to remat or hoist the instruction, but not if it costs more than
477 /// moving the instruction into the appropriate register. Note, we are not
478 /// marking copies from and to the same register class with this flag.
480 /// This method could be called by interface TargetInstrInfo::isAsCheapAsAMove
481 /// for different subtargets.
482 bool isAsCheapAsAMove() const { return Flags & (1ULL << MCID::CheapAsAMove); }
484 /// \brief Returns true if this instruction source operands have special
485 /// register allocation requirements that are not captured by the operand
486 /// register classes. e.g. ARM::STRD's two source registers must be an even /
487 /// odd pair, ARM::STM registers have to be in ascending order. Post-register
488 /// allocation passes should not attempt to change allocations for sources of
489 /// instructions with this flag.
490 bool hasExtraSrcRegAllocReq() const {
491 return Flags & (1ULL << MCID::ExtraSrcRegAllocReq);
494 /// \brief Returns true if this instruction def operands have special register
495 /// allocation requirements that are not captured by the operand register
496 /// classes. e.g. ARM::LDRD's two def registers must be an even / odd pair,
497 /// ARM::LDM registers have to be in ascending order. Post-register
498 /// allocation passes should not attempt to change allocations for definitions
499 /// of instructions with this flag.
500 bool hasExtraDefRegAllocReq() const {
501 return Flags & (1ULL << MCID::ExtraDefRegAllocReq);
504 /// \brief Return a list of registers that are potentially read by any
505 /// instance of this machine instruction. For example, on X86, the "adc"
506 /// instruction adds two register operands and adds the carry bit in from the
507 /// flags register. In this case, the instruction is marked as implicitly
508 /// reading the flags. Likewise, the variable shift instruction on X86 is
509 /// marked as implicitly reading the 'CL' register, which it always does.
511 /// This method returns null if the instruction has no implicit uses.
512 const MCPhysReg *getImplicitUses() const { return ImplicitUses; }
514 /// \brief Return the number of implicit uses this instruction has.
515 unsigned getNumImplicitUses() const {
519 for (; ImplicitUses[i]; ++i) /*empty*/
524 /// \brief Return a list of registers that are potentially written by any
525 /// instance of this machine instruction. For example, on X86, many
526 /// instructions implicitly set the flags register. In this case, they are
527 /// marked as setting the FLAGS. Likewise, many instructions always deposit
528 /// their result in a physical register. For example, the X86 divide
529 /// instruction always deposits the quotient and remainder in the EAX/EDX
530 /// registers. For that instruction, this will return a list containing the
531 /// EAX/EDX/EFLAGS registers.
533 /// This method returns null if the instruction has no implicit defs.
534 const MCPhysReg *getImplicitDefs() const { return ImplicitDefs; }
536 /// \brief Return the number of implicit defs this instruct has.
537 unsigned getNumImplicitDefs() const {
541 for (; ImplicitDefs[i]; ++i) /*empty*/
546 /// \brief Return true if this instruction implicitly
547 /// uses the specified physical register.
548 bool hasImplicitUseOfPhysReg(unsigned Reg) const {
549 if (const MCPhysReg *ImpUses = ImplicitUses)
550 for (; *ImpUses; ++ImpUses)
556 /// \brief Return true if this instruction implicitly
557 /// defines the specified physical register.
558 bool hasImplicitDefOfPhysReg(unsigned Reg,
559 const MCRegisterInfo *MRI = nullptr) const;
561 /// \brief Return the scheduling class for this instruction. The
562 /// scheduling class is an index into the InstrItineraryData table. This
563 /// returns zero if there is no known scheduling information for the
565 unsigned getSchedClass() const { return SchedClass; }
567 /// \brief Return the number of bytes in the encoding of this instruction,
568 /// or zero if the encoding size cannot be known from the opcode.
569 unsigned getSize() const { return Size; }
571 /// \brief Find the index of the first operand in the
572 /// operand list that is used to represent the predicate. It returns -1 if
574 int findFirstPredOperandIdx() const {
575 if (isPredicable()) {
576 for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
577 if (OpInfo[i].isPredicate())
585 /// \brief Return true if this instruction defines the specified physical
586 /// register, either explicitly or implicitly.
587 bool hasDefOfPhysReg(const MCInst &MI, unsigned Reg,
588 const MCRegisterInfo &RI) const;
591 } // end namespace llvm