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_TARGET = 12,
64 /// This holds information about one operand of a machine instruction,
65 /// indicating the register class for register operands, etc.
68 /// This specifies the register class enumeration of the operand
69 /// if the operand is a register. If isLookupPtrRegClass is set, then this is
70 /// an index that is passed to TargetRegisterInfo::getPointerRegClass(x) to
71 /// get a dynamic register class.
74 /// These are flags from the MCOI::OperandFlags enum.
77 /// Information about the type of the operand.
79 /// The lower 16 bits are used to specify which constraints are set.
80 /// The higher 16 bits are used to specify the value of constraints (4 bits
84 /// Set if this operand is a pointer value and it requires a callback
85 /// to look up its register class.
86 bool isLookupPtrRegClass() const {
87 return Flags & (1 << MCOI::LookupPtrRegClass);
90 /// Set if this is one of the operands that made up of the predicate
91 /// operand that controls an isPredicable() instruction.
92 bool isPredicate() const { return Flags & (1 << MCOI::Predicate); }
94 /// Set if this operand is a optional def.
95 bool isOptionalDef() const { return Flags & (1 << MCOI::OptionalDef); }
97 bool isGenericType() const {
98 return OperandType >= MCOI::OPERAND_FIRST_GENERIC &&
99 OperandType <= MCOI::OPERAND_LAST_GENERIC;
102 unsigned getGenericTypeIndex() const {
103 assert(isGenericType() && "non-generic types don't have an index");
104 return OperandType - MCOI::OPERAND_FIRST_GENERIC;
108 //===----------------------------------------------------------------------===//
109 // Machine Instruction Flags and Description
110 //===----------------------------------------------------------------------===//
113 /// These should be considered private to the implementation of the
114 /// MCInstrDesc class. Clients should use the predicate methods on MCInstrDesc,
115 /// not use these directly. These all correspond to bitfields in the
116 /// MCInstrDesc::Flags field.
140 UnmodeledSideEffects,
159 /// Describe properties that are true of each instruction in the target
160 /// description file. This captures information about side effects, register
161 /// use and many other things. There is one instance of this struct for each
162 /// target instruction class, and the MachineInstr class points to this struct
163 /// directly to describe itself.
166 unsigned short Opcode; // The opcode number
167 unsigned short NumOperands; // Num of args (may be more if variable_ops)
168 unsigned char NumDefs; // Num of args that are definitions
169 unsigned char Size; // Number of bytes in encoding.
170 unsigned short SchedClass; // enum identifying instr sched class
171 uint64_t Flags; // Flags identifying machine instr class
172 uint64_t TSFlags; // Target Specific Flag values
173 const MCPhysReg *ImplicitUses; // Registers implicitly read by this instr
174 const MCPhysReg *ImplicitDefs; // Registers implicitly defined by this instr
175 const MCOperandInfo *OpInfo; // 'NumOperands' entries about operands
176 // Subtarget feature that this is deprecated on, if any
177 // -1 implies this is not deprecated by any single feature. It may still be
178 // deprecated due to a "complex" reason, below.
179 int64_t DeprecatedFeature;
181 // A complex method to determine if a certain instruction is deprecated or
182 // not, and return the reason for deprecation.
183 bool (*ComplexDeprecationInfo)(MCInst &, const MCSubtargetInfo &,
186 /// Returns the value of the specific constraint if
187 /// it is set. Returns -1 if it is not set.
188 int getOperandConstraint(unsigned OpNum,
189 MCOI::OperandConstraint Constraint) const {
190 if (OpNum < NumOperands &&
191 (OpInfo[OpNum].Constraints & (1 << Constraint))) {
192 unsigned Pos = 16 + Constraint * 4;
193 return (int)(OpInfo[OpNum].Constraints >> Pos) & 0xf;
198 /// Returns true if a certain instruction is deprecated and if so
199 /// returns the reason in \p Info.
200 bool getDeprecatedInfo(MCInst &MI, const MCSubtargetInfo &STI,
201 std::string &Info) const;
203 /// Return the opcode number for this descriptor.
204 unsigned getOpcode() const { return Opcode; }
206 /// Return the number of declared MachineOperands for this
207 /// MachineInstruction. Note that variadic (isVariadic() returns true)
208 /// instructions may have additional operands at the end of the list, and note
209 /// that the machine instruction may include implicit register def/uses as
211 unsigned getNumOperands() const { return NumOperands; }
213 using const_opInfo_iterator = const MCOperandInfo *;
215 const_opInfo_iterator opInfo_begin() const { return OpInfo; }
216 const_opInfo_iterator opInfo_end() const { return OpInfo + NumOperands; }
218 iterator_range<const_opInfo_iterator> operands() const {
219 return make_range(opInfo_begin(), opInfo_end());
222 /// Return the number of MachineOperands that are register
223 /// definitions. Register definitions always occur at the start of the
224 /// machine operand list. This is the number of "outs" in the .td file,
225 /// and does not include implicit defs.
226 unsigned getNumDefs() const { return NumDefs; }
228 /// Return flags of this instruction.
229 uint64_t getFlags() const { return Flags; }
231 /// Return true if this instruction can have a variable number of
232 /// operands. In this case, the variable operands will be after the normal
233 /// operands but before the implicit definitions and uses (if any are
235 bool isVariadic() const { return Flags & (1ULL << MCID::Variadic); }
237 /// Set if this instruction has an optional definition, e.g.
238 /// ARM instructions which can set condition code if 's' bit is set.
239 bool hasOptionalDef() const { return Flags & (1ULL << MCID::HasOptionalDef); }
241 /// Return true if this is a pseudo instruction that doesn't
242 /// correspond to a real machine instruction.
243 bool isPseudo() const { return Flags & (1ULL << MCID::Pseudo); }
245 /// Return true if the instruction is a return.
246 bool isReturn() const { return Flags & (1ULL << MCID::Return); }
248 /// Return true if the instruction is an add instruction.
249 bool isAdd() const { return Flags & (1ULL << MCID::Add); }
251 /// Return true if this instruction is a trap.
252 bool isTrap() const { return Flags & (1ULL << MCID::Trap); }
254 /// Return true if the instruction is a register to register move.
255 bool isMoveReg() const { return Flags & (1ULL << MCID::MoveReg); }
257 /// Return true if the instruction is a call.
258 bool isCall() const { return Flags & (1ULL << MCID::Call); }
260 /// Returns true if the specified instruction stops control flow
261 /// from executing the instruction immediately following it. Examples include
262 /// unconditional branches and return instructions.
263 bool isBarrier() const { return Flags & (1ULL << MCID::Barrier); }
265 /// Returns true if this instruction part of the terminator for
266 /// a basic block. Typically this is things like return and branch
269 /// Various passes use this to insert code into the bottom of a basic block,
270 /// but before control flow occurs.
271 bool isTerminator() const { return Flags & (1ULL << MCID::Terminator); }
273 /// Returns true if this is a conditional, unconditional, or
274 /// indirect branch. Predicates below can be used to discriminate between
275 /// these cases, and the TargetInstrInfo::AnalyzeBranch method can be used to
276 /// get more information.
277 bool isBranch() const { return Flags & (1ULL << MCID::Branch); }
279 /// Return true if this is an indirect branch, such as a
280 /// branch through a register.
281 bool isIndirectBranch() const { return Flags & (1ULL << MCID::IndirectBranch); }
283 /// Return true if this is a branch which may fall
284 /// through to the next instruction or may transfer control flow to some other
285 /// block. The TargetInstrInfo::AnalyzeBranch method can be used to get more
286 /// information about this branch.
287 bool isConditionalBranch() const {
288 return isBranch() & !isBarrier() & !isIndirectBranch();
291 /// Return true if this is a branch which always
292 /// transfers control flow to some other block. The
293 /// TargetInstrInfo::AnalyzeBranch method can be used to get more information
294 /// about this branch.
295 bool isUnconditionalBranch() const {
296 return isBranch() & isBarrier() & !isIndirectBranch();
299 /// Return true if this is a branch or an instruction which directly
300 /// writes to the program counter. Considered 'may' affect rather than
301 /// 'does' affect as things like predication are not taken into account.
302 bool mayAffectControlFlow(const MCInst &MI, const MCRegisterInfo &RI) const;
304 /// Return true if this instruction has a predicate operand
305 /// that controls execution. It may be set to 'always', or may be set to other
306 /// values. There are various methods in TargetInstrInfo that can be used to
307 /// control and modify the predicate in this instruction.
308 bool isPredicable() const { return Flags & (1ULL << MCID::Predicable); }
310 /// Return true if this instruction is a comparison.
311 bool isCompare() const { return Flags & (1ULL << MCID::Compare); }
313 /// Return true if this instruction is a move immediate
314 /// (including conditional moves) instruction.
315 bool isMoveImmediate() const { return Flags & (1ULL << MCID::MoveImm); }
317 /// Return true if this instruction is a bitcast instruction.
318 bool isBitcast() const { return Flags & (1ULL << MCID::Bitcast); }
320 /// Return true if this is a select instruction.
321 bool isSelect() const { return Flags & (1ULL << MCID::Select); }
323 /// Return true if this instruction cannot be safely
324 /// duplicated. For example, if the instruction has a unique labels attached
325 /// to it, duplicating it would cause multiple definition errors.
326 bool isNotDuplicable() const { return Flags & (1ULL << MCID::NotDuplicable); }
328 /// Returns true if the specified instruction has a delay slot which
329 /// must be filled by the code generator.
330 bool hasDelaySlot() const { return Flags & (1ULL << MCID::DelaySlot); }
332 /// Return true for instructions that can be folded as memory operands
333 /// in other instructions. The most common use for this is instructions that
334 /// are simple loads from memory that don't modify the loaded value in any
335 /// way, but it can also be used for instructions that can be expressed as
336 /// constant-pool loads, such as V_SETALLONES on x86, to allow them to be
337 /// folded when it is beneficial. This should only be set on instructions
338 /// that return a value in their only virtual register definition.
339 bool canFoldAsLoad() const { return Flags & (1ULL << MCID::FoldableAsLoad); }
341 /// Return true if this instruction behaves
342 /// the same way as the generic REG_SEQUENCE instructions.
344 /// dX VMOVDRR rY, rZ
346 /// dX = REG_SEQUENCE rY, ssub_0, rZ, ssub_1.
348 /// Note that for the optimizers to be able to take advantage of
349 /// this property, TargetInstrInfo::getRegSequenceLikeInputs has to be
350 /// override accordingly.
351 bool isRegSequenceLike() const { return Flags & (1ULL << MCID::RegSequence); }
353 /// Return true if this instruction behaves
354 /// the same way as the generic EXTRACT_SUBREG instructions.
356 /// rX, rY VMOVRRD dZ
357 /// is equivalent to two EXTRACT_SUBREG:
358 /// rX = EXTRACT_SUBREG dZ, ssub_0
359 /// rY = EXTRACT_SUBREG dZ, ssub_1
361 /// Note that for the optimizers to be able to take advantage of
362 /// this property, TargetInstrInfo::getExtractSubregLikeInputs has to be
363 /// override accordingly.
364 bool isExtractSubregLike() const {
365 return Flags & (1ULL << MCID::ExtractSubreg);
368 /// Return true if this instruction behaves
369 /// the same way as the generic INSERT_SUBREG instructions.
371 /// dX = VSETLNi32 dY, rZ, Imm
372 /// is equivalent to a INSERT_SUBREG:
373 /// dX = INSERT_SUBREG dY, rZ, translateImmToSubIdx(Imm)
375 /// Note that for the optimizers to be able to take advantage of
376 /// this property, TargetInstrInfo::getInsertSubregLikeInputs has to be
377 /// override accordingly.
378 bool isInsertSubregLike() const { return Flags & (1ULL << MCID::InsertSubreg); }
381 /// Return true if this instruction is convergent.
383 /// Convergent instructions may not be made control-dependent on any
384 /// additional values.
385 bool isConvergent() const { return Flags & (1ULL << MCID::Convergent); }
387 /// Return true if variadic operands of this instruction are definitions.
388 bool variadicOpsAreDefs() const {
389 return Flags & (1ULL << MCID::VariadicOpsAreDefs);
392 //===--------------------------------------------------------------------===//
393 // Side Effect Analysis
394 //===--------------------------------------------------------------------===//
396 /// Return true if this instruction could possibly read memory.
397 /// Instructions with this flag set are not necessarily simple load
398 /// instructions, they may load a value and modify it, for example.
399 bool mayLoad() const { return Flags & (1ULL << MCID::MayLoad); }
401 /// Return true if this instruction could possibly modify memory.
402 /// Instructions with this flag set are not necessarily simple store
403 /// instructions, they may store a modified value based on their operands, or
404 /// may not actually modify anything, for example.
405 bool mayStore() const { return Flags & (1ULL << MCID::MayStore); }
407 /// Return true if this instruction may raise a floating-point exception.
408 bool mayRaiseFPException() const {
409 return Flags & (1ULL << MCID::MayRaiseFPException);
412 /// Return true if this instruction has side
413 /// effects that are not modeled by other flags. This does not return true
414 /// for instructions whose effects are captured by:
416 /// 1. Their operand list and implicit definition/use list. Register use/def
417 /// info is explicit for instructions.
418 /// 2. Memory accesses. Use mayLoad/mayStore.
419 /// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
421 /// Examples of side effects would be modifying 'invisible' machine state like
422 /// a control register, flushing a cache, modifying a register invisible to
424 bool hasUnmodeledSideEffects() const {
425 return Flags & (1ULL << MCID::UnmodeledSideEffects);
428 //===--------------------------------------------------------------------===//
429 // Flags that indicate whether an instruction can be modified by a method.
430 //===--------------------------------------------------------------------===//
432 /// Return true if this may be a 2- or 3-address instruction (of the
433 /// form "X = op Y, Z, ..."), which produces the same result if Y and Z are
434 /// exchanged. If this flag is set, then the
435 /// TargetInstrInfo::commuteInstruction method may be used to hack on the
438 /// Note that this flag may be set on instructions that are only commutable
439 /// sometimes. In these cases, the call to commuteInstruction will fail.
440 /// Also note that some instructions require non-trivial modification to
442 bool isCommutable() const { return Flags & (1ULL << MCID::Commutable); }
444 /// Return true if this is a 2-address instruction which can be changed
445 /// into a 3-address instruction if needed. Doing this transformation can be
446 /// profitable in the register allocator, because it means that the
447 /// instruction can use a 2-address form if possible, but degrade into a less
448 /// efficient form if the source and dest register cannot be assigned to the
449 /// same register. For example, this allows the x86 backend to turn a "shl
450 /// reg, 3" instruction into an LEA instruction, which is the same speed as
451 /// the shift but has bigger code size.
453 /// If this returns true, then the target must implement the
454 /// TargetInstrInfo::convertToThreeAddress method for this instruction, which
455 /// is allowed to fail if the transformation isn't valid for this specific
456 /// instruction (e.g. shl reg, 4 on x86).
458 bool isConvertibleTo3Addr() const {
459 return Flags & (1ULL << MCID::ConvertibleTo3Addr);
462 /// Return true if this instruction requires custom insertion support
463 /// when the DAG scheduler is inserting it into a machine basic block. If
464 /// this is true for the instruction, it basically means that it is a pseudo
465 /// instruction used at SelectionDAG time that is expanded out into magic code
466 /// by the target when MachineInstrs are formed.
468 /// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
469 /// is used to insert this into the MachineBasicBlock.
470 bool usesCustomInsertionHook() const {
471 return Flags & (1ULL << MCID::UsesCustomInserter);
474 /// Return true if this instruction requires *adjustment* after
475 /// instruction selection by calling a target hook. For example, this can be
476 /// used to fill in ARM 's' optional operand depending on whether the
477 /// conditional flag register is used.
478 bool hasPostISelHook() const { return Flags & (1ULL << MCID::HasPostISelHook); }
480 /// Returns true if this instruction is a candidate for remat. This
481 /// flag is only used in TargetInstrInfo method isTriviallyRematerializable.
483 /// If this flag is set, the isReallyTriviallyReMaterializable()
484 /// or isReallyTriviallyReMaterializableGeneric methods are called to verify
485 /// the instruction is really rematable.
486 bool isRematerializable() const {
487 return Flags & (1ULL << MCID::Rematerializable);
490 /// Returns true if this instruction has the same cost (or less) than a
491 /// move instruction. This is useful during certain types of optimizations
492 /// (e.g., remat during two-address conversion or machine licm) where we would
493 /// like to remat or hoist the instruction, but not if it costs more than
494 /// moving the instruction into the appropriate register. Note, we are not
495 /// marking copies from and to the same register class with this flag.
497 /// This method could be called by interface TargetInstrInfo::isAsCheapAsAMove
498 /// for different subtargets.
499 bool isAsCheapAsAMove() const { return Flags & (1ULL << MCID::CheapAsAMove); }
501 /// Returns true if this instruction source operands have special
502 /// register allocation requirements that are not captured by the operand
503 /// register classes. e.g. ARM::STRD's two source registers must be an even /
504 /// odd pair, ARM::STM registers have to be in ascending order. Post-register
505 /// allocation passes should not attempt to change allocations for sources of
506 /// instructions with this flag.
507 bool hasExtraSrcRegAllocReq() const {
508 return Flags & (1ULL << MCID::ExtraSrcRegAllocReq);
511 /// Returns true if this instruction def operands have special register
512 /// allocation requirements that are not captured by the operand register
513 /// classes. e.g. ARM::LDRD's two def registers must be an even / odd pair,
514 /// ARM::LDM registers have to be in ascending order. Post-register
515 /// allocation passes should not attempt to change allocations for definitions
516 /// of instructions with this flag.
517 bool hasExtraDefRegAllocReq() const {
518 return Flags & (1ULL << MCID::ExtraDefRegAllocReq);
521 /// Return a list of registers that are potentially read by any
522 /// instance of this machine instruction. For example, on X86, the "adc"
523 /// instruction adds two register operands and adds the carry bit in from the
524 /// flags register. In this case, the instruction is marked as implicitly
525 /// reading the flags. Likewise, the variable shift instruction on X86 is
526 /// marked as implicitly reading the 'CL' register, which it always does.
528 /// This method returns null if the instruction has no implicit uses.
529 const MCPhysReg *getImplicitUses() const { return ImplicitUses; }
531 /// Return the number of implicit uses this instruction has.
532 unsigned getNumImplicitUses() const {
536 for (; ImplicitUses[i]; ++i) /*empty*/
541 /// Return a list of registers that are potentially written by any
542 /// instance of this machine instruction. For example, on X86, many
543 /// instructions implicitly set the flags register. In this case, they are
544 /// marked as setting the FLAGS. Likewise, many instructions always deposit
545 /// their result in a physical register. For example, the X86 divide
546 /// instruction always deposits the quotient and remainder in the EAX/EDX
547 /// registers. For that instruction, this will return a list containing the
548 /// EAX/EDX/EFLAGS registers.
550 /// This method returns null if the instruction has no implicit defs.
551 const MCPhysReg *getImplicitDefs() const { return ImplicitDefs; }
553 /// Return the number of implicit defs this instruct has.
554 unsigned getNumImplicitDefs() const {
558 for (; ImplicitDefs[i]; ++i) /*empty*/
563 /// Return true if this instruction implicitly
564 /// uses the specified physical register.
565 bool hasImplicitUseOfPhysReg(unsigned Reg) const {
566 if (const MCPhysReg *ImpUses = ImplicitUses)
567 for (; *ImpUses; ++ImpUses)
573 /// Return true if this instruction implicitly
574 /// defines the specified physical register.
575 bool hasImplicitDefOfPhysReg(unsigned Reg,
576 const MCRegisterInfo *MRI = nullptr) const;
578 /// Return the scheduling class for this instruction. The
579 /// scheduling class is an index into the InstrItineraryData table. This
580 /// returns zero if there is no known scheduling information for the
582 unsigned getSchedClass() const { return SchedClass; }
584 /// Return the number of bytes in the encoding of this instruction,
585 /// or zero if the encoding size cannot be known from the opcode.
586 unsigned getSize() const { return Size; }
588 /// Find the index of the first operand in the
589 /// operand list that is used to represent the predicate. It returns -1 if
591 int findFirstPredOperandIdx() const {
592 if (isPredicable()) {
593 for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
594 if (OpInfo[i].isPredicate())
600 /// Return true if this instruction defines the specified physical
601 /// register, either explicitly or implicitly.
602 bool hasDefOfPhysReg(const MCInst &MI, unsigned Reg,
603 const MCRegisterInfo &RI) const;
606 } // end namespace llvm