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 /// 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 /// 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,
65 /// This holds information about one operand of a machine instruction,
66 /// indicating the register class for register operands, etc.
69 /// This specifies the register class enumeration of the operand
70 /// if the operand is a register. If isLookupPtrRegClass is set, then this is
71 /// an index that is passed to TargetRegisterInfo::getPointerRegClass(x) to
72 /// get a dynamic register class.
75 /// These are flags from the MCOI::OperandFlags enum.
78 /// Information about the type of the operand.
80 /// The lower 16 bits are used to specify which constraints are set.
81 /// The higher 16 bits are used to specify the value of constraints (4 bits
85 /// Set if this operand is a pointer value and it requires a callback
86 /// to look up its register class.
87 bool isLookupPtrRegClass() const {
88 return Flags & (1 << MCOI::LookupPtrRegClass);
91 /// Set if this is one of the operands that made up of the predicate
92 /// operand that controls an isPredicable() instruction.
93 bool isPredicate() const { return Flags & (1 << MCOI::Predicate); }
95 /// Set if this operand is a optional def.
96 bool isOptionalDef() const { return Flags & (1 << MCOI::OptionalDef); }
98 bool isGenericType() const {
99 return OperandType >= MCOI::OPERAND_FIRST_GENERIC &&
100 OperandType <= MCOI::OPERAND_LAST_GENERIC;
103 unsigned getGenericTypeIndex() const {
104 assert(isGenericType() && "non-generic types don't have an index");
105 return OperandType - MCOI::OPERAND_FIRST_GENERIC;
109 //===----------------------------------------------------------------------===//
110 // Machine Instruction Flags and Description
111 //===----------------------------------------------------------------------===//
114 /// These should be considered private to the implementation of the
115 /// MCInstrDesc class. Clients should use the predicate methods on MCInstrDesc,
116 /// not use these directly. These all correspond to bitfields in the
117 /// MCInstrDesc::Flags field.
139 UnmodeledSideEffects,
157 /// Describe properties that are true of each instruction in the target
158 /// description file. This captures information about side effects, register
159 /// use and many other things. There is one instance of this struct for each
160 /// target instruction class, and the MachineInstr class points to this struct
161 /// directly to describe itself.
164 unsigned short Opcode; // The opcode number
165 unsigned short NumOperands; // Num of args (may be more if variable_ops)
166 unsigned char NumDefs; // Num of args that are definitions
167 unsigned char Size; // Number of bytes in encoding.
168 unsigned short SchedClass; // enum identifying instr sched class
169 uint64_t Flags; // Flags identifying machine instr class
170 uint64_t TSFlags; // Target Specific Flag values
171 const MCPhysReg *ImplicitUses; // Registers implicitly read by this instr
172 const MCPhysReg *ImplicitDefs; // Registers implicitly defined by this instr
173 const MCOperandInfo *OpInfo; // 'NumOperands' entries about operands
174 // Subtarget feature that this is deprecated on, if any
175 // -1 implies this is not deprecated by any single feature. It may still be
176 // deprecated due to a "complex" reason, below.
177 int64_t DeprecatedFeature;
179 // A complex method to determine if a certain instruction is deprecated or
180 // not, and return the reason for deprecation.
181 bool (*ComplexDeprecationInfo)(MCInst &, const MCSubtargetInfo &,
184 /// Returns the value of the specific constraint if
185 /// it is set. Returns -1 if it is not set.
186 int getOperandConstraint(unsigned OpNum,
187 MCOI::OperandConstraint Constraint) const {
188 if (OpNum < NumOperands &&
189 (OpInfo[OpNum].Constraints & (1 << Constraint))) {
190 unsigned Pos = 16 + Constraint * 4;
191 return (int)(OpInfo[OpNum].Constraints >> Pos) & 0xf;
196 /// Returns true if a certain instruction is deprecated and if so
197 /// returns the reason in \p Info.
198 bool getDeprecatedInfo(MCInst &MI, const MCSubtargetInfo &STI,
199 std::string &Info) const;
201 /// Return the opcode number for this descriptor.
202 unsigned getOpcode() const { return Opcode; }
204 /// Return the number of declared MachineOperands for this
205 /// MachineInstruction. Note that variadic (isVariadic() returns true)
206 /// instructions may have additional operands at the end of the list, and note
207 /// that the machine instruction may include implicit register def/uses as
209 unsigned getNumOperands() const { return NumOperands; }
211 using const_opInfo_iterator = const MCOperandInfo *;
213 const_opInfo_iterator opInfo_begin() const { return OpInfo; }
214 const_opInfo_iterator opInfo_end() const { return OpInfo + NumOperands; }
216 iterator_range<const_opInfo_iterator> operands() const {
217 return make_range(opInfo_begin(), opInfo_end());
220 /// Return the number of MachineOperands that are register
221 /// definitions. Register definitions always occur at the start of the
222 /// machine operand list. This is the number of "outs" in the .td file,
223 /// and does not include implicit defs.
224 unsigned getNumDefs() const { return NumDefs; }
226 /// Return flags of this instruction.
227 uint64_t getFlags() const { return Flags; }
229 /// Return true if this instruction can have a variable number of
230 /// operands. In this case, the variable operands will be after the normal
231 /// operands but before the implicit definitions and uses (if any are
233 bool isVariadic() const { return Flags & (1ULL << MCID::Variadic); }
235 /// Set if this instruction has an optional definition, e.g.
236 /// ARM instructions which can set condition code if 's' bit is set.
237 bool hasOptionalDef() const { return Flags & (1ULL << MCID::HasOptionalDef); }
239 /// Return true if this is a pseudo instruction that doesn't
240 /// correspond to a real machine instruction.
241 bool isPseudo() const { return Flags & (1ULL << MCID::Pseudo); }
243 /// Return true if the instruction is a return.
244 bool isReturn() const { return Flags & (1ULL << MCID::Return); }
246 /// Return true if the instruction is an add instruction.
247 bool isAdd() const { return Flags & (1ULL << MCID::Add); }
249 /// Return true if this instruction is a trap.
250 bool isTrap() const { return Flags & (1ULL << MCID::Trap); }
252 /// Return true if the instruction is a register to register move.
253 bool isMoveReg() const { return Flags & (1ULL << MCID::MoveReg); }
255 /// Return true if the instruction is a call.
256 bool isCall() const { return Flags & (1ULL << MCID::Call); }
258 /// Returns true if the specified instruction stops control flow
259 /// from executing the instruction immediately following it. Examples include
260 /// unconditional branches and return instructions.
261 bool isBarrier() const { return Flags & (1ULL << MCID::Barrier); }
263 /// Returns true if this instruction part of the terminator for
264 /// a basic block. Typically this is things like return and branch
267 /// Various passes use this to insert code into the bottom of a basic block,
268 /// but before control flow occurs.
269 bool isTerminator() const { return Flags & (1ULL << MCID::Terminator); }
271 /// Returns true if this is a conditional, unconditional, or
272 /// indirect branch. Predicates below can be used to discriminate between
273 /// these cases, and the TargetInstrInfo::AnalyzeBranch method can be used to
274 /// get more information.
275 bool isBranch() const { return Flags & (1ULL << MCID::Branch); }
277 /// Return true if this is an indirect branch, such as a
278 /// branch through a register.
279 bool isIndirectBranch() const { return Flags & (1ULL << MCID::IndirectBranch); }
281 /// Return true if this is a branch which may fall
282 /// through to the next instruction or may transfer control flow to some other
283 /// block. The TargetInstrInfo::AnalyzeBranch method can be used to get more
284 /// information about this branch.
285 bool isConditionalBranch() const {
286 return isBranch() & !isBarrier() & !isIndirectBranch();
289 /// Return true if this is a branch which always
290 /// transfers control flow to some other block. The
291 /// TargetInstrInfo::AnalyzeBranch method can be used to get more information
292 /// about this branch.
293 bool isUnconditionalBranch() const {
294 return isBranch() & isBarrier() & !isIndirectBranch();
297 /// Return true if this is a branch or an instruction which directly
298 /// writes to the program counter. Considered 'may' affect rather than
299 /// 'does' affect as things like predication are not taken into account.
300 bool mayAffectControlFlow(const MCInst &MI, const MCRegisterInfo &RI) const;
302 /// Return true if this instruction has a predicate operand
303 /// that controls execution. It may be set to 'always', or may be set to other
304 /// values. There are various methods in TargetInstrInfo that can be used to
305 /// control and modify the predicate in this instruction.
306 bool isPredicable() const { return Flags & (1ULL << MCID::Predicable); }
308 /// Return true if this instruction is a comparison.
309 bool isCompare() const { return Flags & (1ULL << MCID::Compare); }
311 /// Return true if this instruction is a move immediate
312 /// (including conditional moves) instruction.
313 bool isMoveImmediate() const { return Flags & (1ULL << MCID::MoveImm); }
315 /// Return true if this instruction is a bitcast instruction.
316 bool isBitcast() const { return Flags & (1ULL << MCID::Bitcast); }
318 /// Return true if this is a select instruction.
319 bool isSelect() const { return Flags & (1ULL << MCID::Select); }
321 /// Return true if this instruction cannot be safely
322 /// duplicated. For example, if the instruction has a unique labels attached
323 /// to it, duplicating it would cause multiple definition errors.
324 bool isNotDuplicable() const { return Flags & (1ULL << MCID::NotDuplicable); }
326 /// Returns true if the specified instruction has a delay slot which
327 /// must be filled by the code generator.
328 bool hasDelaySlot() const { return Flags & (1ULL << MCID::DelaySlot); }
330 /// Return true for instructions that can be folded as memory operands
331 /// in other instructions. The most common use for this is instructions that
332 /// are simple loads from memory that don't modify the loaded value in any
333 /// way, but it can also be used for instructions that can be expressed as
334 /// constant-pool loads, such as V_SETALLONES on x86, to allow them to be
335 /// folded when it is beneficial. This should only be set on instructions
336 /// that return a value in their only virtual register definition.
337 bool canFoldAsLoad() const { return Flags & (1ULL << MCID::FoldableAsLoad); }
339 /// Return true if this instruction behaves
340 /// the same way as the generic REG_SEQUENCE instructions.
342 /// dX VMOVDRR rY, rZ
344 /// dX = REG_SEQUENCE rY, ssub_0, rZ, ssub_1.
346 /// Note that for the optimizers to be able to take advantage of
347 /// this property, TargetInstrInfo::getRegSequenceLikeInputs has to be
348 /// override accordingly.
349 bool isRegSequenceLike() const { return Flags & (1ULL << MCID::RegSequence); }
351 /// Return true if this instruction behaves
352 /// the same way as the generic EXTRACT_SUBREG instructions.
354 /// rX, rY VMOVRRD dZ
355 /// is equivalent to two EXTRACT_SUBREG:
356 /// rX = EXTRACT_SUBREG dZ, ssub_0
357 /// rY = EXTRACT_SUBREG dZ, ssub_1
359 /// Note that for the optimizers to be able to take advantage of
360 /// this property, TargetInstrInfo::getExtractSubregLikeInputs has to be
361 /// override accordingly.
362 bool isExtractSubregLike() const {
363 return Flags & (1ULL << MCID::ExtractSubreg);
366 /// Return true if this instruction behaves
367 /// the same way as the generic INSERT_SUBREG instructions.
369 /// dX = VSETLNi32 dY, rZ, Imm
370 /// is equivalent to a INSERT_SUBREG:
371 /// dX = INSERT_SUBREG dY, rZ, translateImmToSubIdx(Imm)
373 /// Note that for the optimizers to be able to take advantage of
374 /// this property, TargetInstrInfo::getInsertSubregLikeInputs has to be
375 /// override accordingly.
376 bool isInsertSubregLike() const { return Flags & (1ULL << MCID::InsertSubreg); }
379 /// Return true if this instruction is convergent.
381 /// Convergent instructions may not be made control-dependent on any
382 /// additional values.
383 bool isConvergent() const { return Flags & (1ULL << MCID::Convergent); }
385 //===--------------------------------------------------------------------===//
386 // Side Effect Analysis
387 //===--------------------------------------------------------------------===//
389 /// Return true if this instruction could possibly read memory.
390 /// Instructions with this flag set are not necessarily simple load
391 /// instructions, they may load a value and modify it, for example.
392 bool mayLoad() const { return Flags & (1ULL << MCID::MayLoad); }
394 /// Return true if this instruction could possibly modify memory.
395 /// Instructions with this flag set are not necessarily simple store
396 /// instructions, they may store a modified value based on their operands, or
397 /// may not actually modify anything, for example.
398 bool mayStore() const { return Flags & (1ULL << MCID::MayStore); }
400 /// Return true if this instruction has side
401 /// effects that are not modeled by other flags. This does not return true
402 /// for instructions whose effects are captured by:
404 /// 1. Their operand list and implicit definition/use list. Register use/def
405 /// info is explicit for instructions.
406 /// 2. Memory accesses. Use mayLoad/mayStore.
407 /// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
409 /// Examples of side effects would be modifying 'invisible' machine state like
410 /// a control register, flushing a cache, modifying a register invisible to
412 bool hasUnmodeledSideEffects() const {
413 return Flags & (1ULL << MCID::UnmodeledSideEffects);
416 //===--------------------------------------------------------------------===//
417 // Flags that indicate whether an instruction can be modified by a method.
418 //===--------------------------------------------------------------------===//
420 /// Return true if this may be a 2- or 3-address instruction (of the
421 /// form "X = op Y, Z, ..."), which produces the same result if Y and Z are
422 /// exchanged. If this flag is set, then the
423 /// TargetInstrInfo::commuteInstruction method may be used to hack on the
426 /// Note that this flag may be set on instructions that are only commutable
427 /// sometimes. In these cases, the call to commuteInstruction will fail.
428 /// Also note that some instructions require non-trivial modification to
430 bool isCommutable() const { return Flags & (1ULL << MCID::Commutable); }
432 /// Return true if this is a 2-address instruction which can be changed
433 /// into a 3-address instruction if needed. Doing this transformation can be
434 /// profitable in the register allocator, because it means that the
435 /// instruction can use a 2-address form if possible, but degrade into a less
436 /// efficient form if the source and dest register cannot be assigned to the
437 /// same register. For example, this allows the x86 backend to turn a "shl
438 /// reg, 3" instruction into an LEA instruction, which is the same speed as
439 /// the shift but has bigger code size.
441 /// If this returns true, then the target must implement the
442 /// TargetInstrInfo::convertToThreeAddress method for this instruction, which
443 /// is allowed to fail if the transformation isn't valid for this specific
444 /// instruction (e.g. shl reg, 4 on x86).
446 bool isConvertibleTo3Addr() const {
447 return Flags & (1ULL << MCID::ConvertibleTo3Addr);
450 /// Return true if this instruction requires custom insertion support
451 /// when the DAG scheduler is inserting it into a machine basic block. If
452 /// this is true for the instruction, it basically means that it is a pseudo
453 /// instruction used at SelectionDAG time that is expanded out into magic code
454 /// by the target when MachineInstrs are formed.
456 /// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
457 /// is used to insert this into the MachineBasicBlock.
458 bool usesCustomInsertionHook() const {
459 return Flags & (1ULL << MCID::UsesCustomInserter);
462 /// Return true if this instruction requires *adjustment* after
463 /// instruction selection by calling a target hook. For example, this can be
464 /// used to fill in ARM 's' optional operand depending on whether the
465 /// conditional flag register is used.
466 bool hasPostISelHook() const { return Flags & (1ULL << MCID::HasPostISelHook); }
468 /// Returns true if this instruction is a candidate for remat. This
469 /// flag is only used in TargetInstrInfo method isTriviallyRematerializable.
471 /// If this flag is set, the isReallyTriviallyReMaterializable()
472 /// or isReallyTriviallyReMaterializableGeneric methods are called to verify
473 /// the instruction is really rematable.
474 bool isRematerializable() const {
475 return Flags & (1ULL << MCID::Rematerializable);
478 /// Returns true if this instruction has the same cost (or less) than a
479 /// move instruction. This is useful during certain types of optimizations
480 /// (e.g., remat during two-address conversion or machine licm) where we would
481 /// like to remat or hoist the instruction, but not if it costs more than
482 /// moving the instruction into the appropriate register. Note, we are not
483 /// marking copies from and to the same register class with this flag.
485 /// This method could be called by interface TargetInstrInfo::isAsCheapAsAMove
486 /// for different subtargets.
487 bool isAsCheapAsAMove() const { return Flags & (1ULL << MCID::CheapAsAMove); }
489 /// Returns true if this instruction source operands have special
490 /// register allocation requirements that are not captured by the operand
491 /// register classes. e.g. ARM::STRD's two source registers must be an even /
492 /// odd pair, ARM::STM registers have to be in ascending order. Post-register
493 /// allocation passes should not attempt to change allocations for sources of
494 /// instructions with this flag.
495 bool hasExtraSrcRegAllocReq() const {
496 return Flags & (1ULL << MCID::ExtraSrcRegAllocReq);
499 /// Returns true if this instruction def operands have special register
500 /// allocation requirements that are not captured by the operand register
501 /// classes. e.g. ARM::LDRD's two def registers must be an even / odd pair,
502 /// ARM::LDM registers have to be in ascending order. Post-register
503 /// allocation passes should not attempt to change allocations for definitions
504 /// of instructions with this flag.
505 bool hasExtraDefRegAllocReq() const {
506 return Flags & (1ULL << MCID::ExtraDefRegAllocReq);
509 /// Return a list of registers that are potentially read by any
510 /// instance of this machine instruction. For example, on X86, the "adc"
511 /// instruction adds two register operands and adds the carry bit in from the
512 /// flags register. In this case, the instruction is marked as implicitly
513 /// reading the flags. Likewise, the variable shift instruction on X86 is
514 /// marked as implicitly reading the 'CL' register, which it always does.
516 /// This method returns null if the instruction has no implicit uses.
517 const MCPhysReg *getImplicitUses() const { return ImplicitUses; }
519 /// Return the number of implicit uses this instruction has.
520 unsigned getNumImplicitUses() const {
524 for (; ImplicitUses[i]; ++i) /*empty*/
529 /// Return a list of registers that are potentially written by any
530 /// instance of this machine instruction. For example, on X86, many
531 /// instructions implicitly set the flags register. In this case, they are
532 /// marked as setting the FLAGS. Likewise, many instructions always deposit
533 /// their result in a physical register. For example, the X86 divide
534 /// instruction always deposits the quotient and remainder in the EAX/EDX
535 /// registers. For that instruction, this will return a list containing the
536 /// EAX/EDX/EFLAGS registers.
538 /// This method returns null if the instruction has no implicit defs.
539 const MCPhysReg *getImplicitDefs() const { return ImplicitDefs; }
541 /// Return the number of implicit defs this instruct has.
542 unsigned getNumImplicitDefs() const {
546 for (; ImplicitDefs[i]; ++i) /*empty*/
551 /// Return true if this instruction implicitly
552 /// uses the specified physical register.
553 bool hasImplicitUseOfPhysReg(unsigned Reg) const {
554 if (const MCPhysReg *ImpUses = ImplicitUses)
555 for (; *ImpUses; ++ImpUses)
561 /// Return true if this instruction implicitly
562 /// defines the specified physical register.
563 bool hasImplicitDefOfPhysReg(unsigned Reg,
564 const MCRegisterInfo *MRI = nullptr) const;
566 /// Return the scheduling class for this instruction. The
567 /// scheduling class is an index into the InstrItineraryData table. This
568 /// returns zero if there is no known scheduling information for the
570 unsigned getSchedClass() const { return SchedClass; }
572 /// Return the number of bytes in the encoding of this instruction,
573 /// or zero if the encoding size cannot be known from the opcode.
574 unsigned getSize() const { return Size; }
576 /// Find the index of the first operand in the
577 /// operand list that is used to represent the predicate. It returns -1 if
579 int findFirstPredOperandIdx() const {
580 if (isPredicable()) {
581 for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
582 if (OpInfo[i].isPredicate())
588 /// Return true if this instruction defines the specified physical
589 /// register, either explicitly or implicitly.
590 bool hasDefOfPhysReg(const MCInst &MI, unsigned Reg,
591 const MCRegisterInfo &RI) const;
594 } // end namespace llvm