1 //===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- 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 describes the target machine instruction set to the code generator.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_TARGET_TARGETINSTRINFO_H
15 #define LLVM_TARGET_TARGETINSTRINFO_H
17 #include "llvm/Target/TargetInstrDesc.h"
18 #include "llvm/CodeGen/MachineFunction.h"
23 class TargetRegisterClass;
24 class TargetRegisterInfo;
26 class CalleeSavedInfo;
29 class MachineMemOperand;
31 template<class T> class SmallVectorImpl;
34 //---------------------------------------------------------------------------
36 /// TargetInstrInfo - Interface to description of machine instruction set
38 class TargetInstrInfo {
39 const TargetInstrDesc *Descriptors; // Raw array to allow static init'n
40 unsigned NumOpcodes; // Number of entries in the desc array
42 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
43 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
45 TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes);
46 virtual ~TargetInstrInfo();
48 // Invariant opcodes: All instruction sets have these as their low opcodes.
56 /// KILL - This instruction is a noop that is used only to adjust the liveness
57 /// of registers. This can be useful when dealing with sub-registers.
60 /// EXTRACT_SUBREG - This instruction takes two operands: a register
61 /// that has subregisters, and a subregister index. It returns the
62 /// extracted subregister value. This is commonly used to implement
63 /// truncation operations on target architectures which support it.
66 /// INSERT_SUBREG - This instruction takes three operands: a register
67 /// that has subregisters, a register providing an insert value, and a
68 /// subregister index. It returns the value of the first register with
69 /// the value of the second register inserted. The first register is
70 /// often defined by an IMPLICIT_DEF, as is commonly used to implement
71 /// anyext operations on target architectures which support it.
74 /// IMPLICIT_DEF - This is the MachineInstr-level equivalent of undef.
77 /// SUBREG_TO_REG - This instruction is similar to INSERT_SUBREG except
78 /// that the first operand is an immediate integer constant. This constant
79 /// is often zero, as is commonly used to implement zext operations on
80 /// target architectures which support it, such as with x86-64 (with
81 /// zext from i32 to i64 via implicit zero-extension).
84 /// COPY_TO_REGCLASS - This instruction is a placeholder for a plain
85 /// register-to-register copy into a specific register class. This is only
86 /// used between instruction selection and MachineInstr creation, before
87 /// virtual registers have been created for all the instructions, and it's
88 /// only needed in cases where the register classes implied by the
89 /// instructions are insufficient. The actual MachineInstrs to perform
90 /// the copy are emitted with the TargetInstrInfo::copyRegToReg hook.
91 COPY_TO_REGCLASS = 10,
93 // DEBUG_VALUE - a mapping of the llvm.dbg.value intrinsic
96 // DEBUG_DECLARE - a mapping of the llvm.dbg.declare intrinsic
100 unsigned getNumOpcodes() const { return NumOpcodes; }
102 /// get - Return the machine instruction descriptor that corresponds to the
103 /// specified instruction opcode.
105 const TargetInstrDesc &get(unsigned Opcode) const {
106 assert(Opcode < NumOpcodes && "Invalid opcode!");
107 return Descriptors[Opcode];
110 /// isTriviallyReMaterializable - Return true if the instruction is trivially
111 /// rematerializable, meaning it has no side effects and requires no operands
112 /// that aren't always available.
113 bool isTriviallyReMaterializable(const MachineInstr *MI,
114 AliasAnalysis *AA = 0) const {
115 return MI->getOpcode() == IMPLICIT_DEF ||
116 (MI->getDesc().isRematerializable() &&
117 (isReallyTriviallyReMaterializable(MI, AA) ||
118 isReallyTriviallyReMaterializableGeneric(MI, AA)));
122 /// isReallyTriviallyReMaterializable - For instructions with opcodes for
123 /// which the M_REMATERIALIZABLE flag is set, this hook lets the target
124 /// specify whether the instruction is actually trivially rematerializable,
125 /// taking into consideration its operands. This predicate must return false
126 /// if the instruction has any side effects other than producing a value, or
127 /// if it requres any address registers that are not always available.
128 virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
129 AliasAnalysis *AA) const {
134 /// isReallyTriviallyReMaterializableGeneric - For instructions with opcodes
135 /// for which the M_REMATERIALIZABLE flag is set and the target hook
136 /// isReallyTriviallyReMaterializable returns false, this function does
137 /// target-independent tests to determine if the instruction is really
138 /// trivially rematerializable.
139 bool isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
140 AliasAnalysis *AA) const;
143 /// isMoveInstr - Return true if the instruction is a register to register
144 /// move and return the source and dest operands and their sub-register
145 /// indices by reference.
146 virtual bool isMoveInstr(const MachineInstr& MI,
147 unsigned& SrcReg, unsigned& DstReg,
148 unsigned& SrcSubIdx, unsigned& DstSubIdx) const {
152 /// isCoalescableExtInstr - Return true if the instruction is a "coalescable"
153 /// extension instruction. That is, it's like a copy where it's legal for the
154 /// source to overlap the destination. e.g. X86::MOVSX64rr32. If this returns
155 /// true, then it's expected the pre-extension value is available as a subreg
156 /// of the result register. This also returns the sub-register index in
158 virtual bool isCoalescableExtInstr(const MachineInstr &MI,
159 unsigned &SrcReg, unsigned &DstReg,
160 unsigned &SubIdx) const {
164 /// isIdentityCopy - Return true if the instruction is a copy (or
165 /// extract_subreg, insert_subreg, subreg_to_reg) where the source and
166 /// destination registers are the same.
167 bool isIdentityCopy(const MachineInstr &MI) const {
168 unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
169 if (isMoveInstr(MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
173 if (MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG &&
174 MI.getOperand(0).getReg() == MI.getOperand(1).getReg())
177 if ((MI.getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
178 MI.getOpcode() == TargetInstrInfo::SUBREG_TO_REG) &&
179 MI.getOperand(0).getReg() == MI.getOperand(2).getReg())
184 /// isLoadFromStackSlot - If the specified machine instruction is a direct
185 /// load from a stack slot, return the virtual or physical register number of
186 /// the destination along with the FrameIndex of the loaded stack slot. If
187 /// not, return 0. This predicate must return 0 if the instruction has
188 /// any side effects other than loading from the stack slot.
189 virtual unsigned isLoadFromStackSlot(const MachineInstr *MI,
190 int &FrameIndex) const {
194 /// isLoadFromStackSlotPostFE - Check for post-frame ptr elimination
195 /// stack locations as well. This uses a heuristic so it isn't
196 /// reliable for correctness.
197 virtual unsigned isLoadFromStackSlotPostFE(const MachineInstr *MI,
198 int &FrameIndex) const {
202 /// hasLoadFromStackSlot - If the specified machine instruction has
203 /// a load from a stack slot, return true along with the FrameIndex
204 /// of the loaded stack slot and the machine mem operand containing
205 /// the reference. If not, return false. Unlike
206 /// isLoadFromStackSlot, this returns true for any instructions that
207 /// loads from the stack. This is just a hint, as some cases may be
209 virtual bool hasLoadFromStackSlot(const MachineInstr *MI,
210 const MachineMemOperand *&MMO,
211 int &FrameIndex) const {
215 /// isStoreToStackSlot - If the specified machine instruction is a direct
216 /// store to a stack slot, return the virtual or physical register number of
217 /// the source reg along with the FrameIndex of the loaded stack slot. If
218 /// not, return 0. This predicate must return 0 if the instruction has
219 /// any side effects other than storing to the stack slot.
220 virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
221 int &FrameIndex) const {
225 /// isStoreToStackSlotPostFE - Check for post-frame ptr elimination
226 /// stack locations as well. This uses a heuristic so it isn't
227 /// reliable for correctness.
228 virtual unsigned isStoreToStackSlotPostFE(const MachineInstr *MI,
229 int &FrameIndex) const {
233 /// hasStoreToStackSlot - If the specified machine instruction has a
234 /// store to a stack slot, return true along with the FrameIndex of
235 /// the loaded stack slot and the machine mem operand containing the
236 /// reference. If not, return false. Unlike isStoreToStackSlot,
237 /// this returns true for any instructions that loads from the
238 /// stack. This is just a hint, as some cases may be missed.
239 virtual bool hasStoreToStackSlot(const MachineInstr *MI,
240 const MachineMemOperand *&MMO,
241 int &FrameIndex) const {
245 /// reMaterialize - Re-issue the specified 'original' instruction at the
246 /// specific location targeting a new destination register.
247 virtual void reMaterialize(MachineBasicBlock &MBB,
248 MachineBasicBlock::iterator MI,
249 unsigned DestReg, unsigned SubIdx,
250 const MachineInstr *Orig,
251 const TargetRegisterInfo *TRI) const = 0;
253 /// duplicate - Create a duplicate of the Orig instruction in MF. This is like
254 /// MachineFunction::CloneMachineInstr(), but the target may update operands
255 /// that are required to be unique.
257 /// The instruction must be duplicable as indicated by isNotDuplicable().
258 virtual MachineInstr *duplicate(MachineInstr *Orig,
259 MachineFunction &MF) const = 0;
261 /// convertToThreeAddress - This method must be implemented by targets that
262 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
263 /// may be able to convert a two-address instruction into one or more true
264 /// three-address instructions on demand. This allows the X86 target (for
265 /// example) to convert ADD and SHL instructions into LEA instructions if they
266 /// would require register copies due to two-addressness.
268 /// This method returns a null pointer if the transformation cannot be
269 /// performed, otherwise it returns the last new instruction.
271 virtual MachineInstr *
272 convertToThreeAddress(MachineFunction::iterator &MFI,
273 MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const {
277 /// commuteInstruction - If a target has any instructions that are commutable,
278 /// but require converting to a different instruction or making non-trivial
279 /// changes to commute them, this method can overloaded to do this. The
280 /// default implementation of this method simply swaps the first two operands
281 /// of MI and returns it.
283 /// If a target wants to make more aggressive changes, they can construct and
284 /// return a new machine instruction. If an instruction cannot commute, it
285 /// can also return null.
287 /// If NewMI is true, then a new machine instruction must be created.
289 virtual MachineInstr *commuteInstruction(MachineInstr *MI,
290 bool NewMI = false) const = 0;
292 /// findCommutedOpIndices - If specified MI is commutable, return the two
293 /// operand indices that would swap value. Return true if the instruction
294 /// is not in a form which this routine understands.
295 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
296 unsigned &SrcOpIdx2) const = 0;
298 /// isIdentical - Return true if two instructions are identical. This differs
299 /// from MachineInstr::isIdenticalTo() in that it does not require the
300 /// virtual destination registers to be the same. This is used by MachineLICM
301 /// and other MI passes to perform CSE.
302 virtual bool isIdentical(const MachineInstr *MI,
303 const MachineInstr *Other,
304 const MachineRegisterInfo *MRI) const = 0;
306 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
307 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't
308 /// implemented for a target). Upon success, this returns false and returns
309 /// with the following information in various cases:
311 /// 1. If this block ends with no branches (it just falls through to its succ)
312 /// just return false, leaving TBB/FBB null.
313 /// 2. If this block ends with only an unconditional branch, it sets TBB to be
314 /// the destination block.
315 /// 3. If this block ends with a conditional branch and it falls through to a
316 /// successor block, it sets TBB to be the branch destination block and a
317 /// list of operands that evaluate the condition. These operands can be
318 /// passed to other TargetInstrInfo methods to create new branches.
319 /// 4. If this block ends with a conditional branch followed by an
320 /// unconditional branch, it returns the 'true' destination in TBB, the
321 /// 'false' destination in FBB, and a list of operands that evaluate the
322 /// condition. These operands can be passed to other TargetInstrInfo
323 /// methods to create new branches.
325 /// Note that RemoveBranch and InsertBranch must be implemented to support
326 /// cases where this method returns success.
328 /// If AllowModify is true, then this routine is allowed to modify the basic
329 /// block (e.g. delete instructions after the unconditional branch).
331 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
332 MachineBasicBlock *&FBB,
333 SmallVectorImpl<MachineOperand> &Cond,
334 bool AllowModify = false) const {
338 /// RemoveBranch - Remove the branching code at the end of the specific MBB.
339 /// This is only invoked in cases where AnalyzeBranch returns success. It
340 /// returns the number of instructions that were removed.
341 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
342 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
346 /// InsertBranch - Insert branch code into the end of the specified
347 /// MachineBasicBlock. The operands to this method are the same as those
348 /// returned by AnalyzeBranch. This is only invoked in cases where
349 /// AnalyzeBranch returns success. It returns the number of instructions
352 /// It is also invoked by tail merging to add unconditional branches in
353 /// cases where AnalyzeBranch doesn't apply because there was no original
354 /// branch to analyze. At least this much must be implemented, else tail
355 /// merging needs to be disabled.
356 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
357 MachineBasicBlock *FBB,
358 const SmallVectorImpl<MachineOperand> &Cond) const {
359 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
363 /// copyRegToReg - Emit instructions to copy between a pair of registers. It
364 /// returns false if the target does not how to copy between the specified
366 virtual bool copyRegToReg(MachineBasicBlock &MBB,
367 MachineBasicBlock::iterator MI,
368 unsigned DestReg, unsigned SrcReg,
369 const TargetRegisterClass *DestRC,
370 const TargetRegisterClass *SrcRC) const {
371 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!");
375 /// storeRegToStackSlot - Store the specified register of the given register
376 /// class to the specified stack frame index. The store instruction is to be
377 /// added to the given machine basic block before the specified machine
378 /// instruction. If isKill is true, the register operand is the last use and
379 /// must be marked kill.
380 virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
381 MachineBasicBlock::iterator MI,
382 unsigned SrcReg, bool isKill, int FrameIndex,
383 const TargetRegisterClass *RC) const {
384 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
387 /// loadRegFromStackSlot - Load the specified register of the given register
388 /// class from the specified stack frame index. The load instruction is to be
389 /// added to the given machine basic block before the specified machine
391 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
392 MachineBasicBlock::iterator MI,
393 unsigned DestReg, int FrameIndex,
394 const TargetRegisterClass *RC) const {
395 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
398 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
399 /// saved registers and returns true if it isn't possible / profitable to do
400 /// so by issuing a series of store instructions via
401 /// storeRegToStackSlot(). Returns false otherwise.
402 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
403 MachineBasicBlock::iterator MI,
404 const std::vector<CalleeSavedInfo> &CSI) const {
408 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee
409 /// saved registers and returns true if it isn't possible / profitable to do
410 /// so by issuing a series of load instructions via loadRegToStackSlot().
411 /// Returns false otherwise.
412 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
413 MachineBasicBlock::iterator MI,
414 const std::vector<CalleeSavedInfo> &CSI) const {
418 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack
419 /// slot into the specified machine instruction for the specified operand(s).
420 /// If this is possible, a new instruction is returned with the specified
421 /// operand folded, otherwise NULL is returned. The client is responsible for
422 /// removing the old instruction and adding the new one in the instruction
424 MachineInstr* foldMemoryOperand(MachineFunction &MF,
426 const SmallVectorImpl<unsigned> &Ops,
427 int FrameIndex) const;
429 /// foldMemoryOperand - Same as the previous version except it allows folding
430 /// of any load and store from / to any address, not just from a specific
432 MachineInstr* foldMemoryOperand(MachineFunction &MF,
434 const SmallVectorImpl<unsigned> &Ops,
435 MachineInstr* LoadMI) const;
438 /// foldMemoryOperandImpl - Target-dependent implementation for
439 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will
440 /// take care of adding a MachineMemOperand to the newly created instruction.
441 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
443 const SmallVectorImpl<unsigned> &Ops,
444 int FrameIndex) const {
448 /// foldMemoryOperandImpl - Target-dependent implementation for
449 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will
450 /// take care of adding a MachineMemOperand to the newly created instruction.
451 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
453 const SmallVectorImpl<unsigned> &Ops,
454 MachineInstr* LoadMI) const {
459 /// canFoldMemoryOperand - Returns true for the specified load / store if
460 /// folding is possible.
462 bool canFoldMemoryOperand(const MachineInstr *MI,
463 const SmallVectorImpl<unsigned> &Ops) const {
467 /// unfoldMemoryOperand - Separate a single instruction which folded a load or
468 /// a store or a load and a store into two or more instruction. If this is
469 /// possible, returns true as well as the new instructions by reference.
470 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
471 unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
472 SmallVectorImpl<MachineInstr*> &NewMIs) const{
476 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
477 SmallVectorImpl<SDNode*> &NewNodes) const {
481 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
482 /// instruction after load / store are unfolded from an instruction of the
483 /// specified opcode. It returns zero if the specified unfolding is not
484 /// possible. If LoadRegIndex is non-null, it is filled in with the operand
485 /// index of the operand which will hold the register holding the loaded
487 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
488 bool UnfoldLoad, bool UnfoldStore,
489 unsigned *LoadRegIndex = 0) const {
493 /// ReverseBranchCondition - Reverses the branch condition of the specified
494 /// condition list, returning false on success and true if it cannot be
497 bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
501 /// insertNoop - Insert a noop into the instruction stream at the specified
503 virtual void insertNoop(MachineBasicBlock &MBB,
504 MachineBasicBlock::iterator MI) const;
506 /// isPredicated - Returns true if the instruction is already predicated.
508 virtual bool isPredicated(const MachineInstr *MI) const {
512 /// isUnpredicatedTerminator - Returns true if the instruction is a
513 /// terminator instruction that has not been predicated.
514 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
516 /// PredicateInstruction - Convert the instruction into a predicated
517 /// instruction. It returns true if the operation was successful.
519 bool PredicateInstruction(MachineInstr *MI,
520 const SmallVectorImpl<MachineOperand> &Pred) const = 0;
522 /// SubsumesPredicate - Returns true if the first specified predicate
523 /// subsumes the second, e.g. GE subsumes GT.
525 bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1,
526 const SmallVectorImpl<MachineOperand> &Pred2) const {
530 /// DefinesPredicate - If the specified instruction defines any predicate
531 /// or condition code register(s) used for predication, returns true as well
532 /// as the definition predicate(s) by reference.
533 virtual bool DefinesPredicate(MachineInstr *MI,
534 std::vector<MachineOperand> &Pred) const {
538 /// isPredicable - Return true if the specified instruction can be predicated.
539 /// By default, this returns true for every instruction with a
540 /// PredicateOperand.
541 virtual bool isPredicable(MachineInstr *MI) const {
542 return MI->getDesc().isPredicable();
545 /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
546 /// instruction that defines the specified register class.
547 virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const {
551 /// GetInstSize - Returns the size of the specified Instruction.
553 virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const {
554 assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!");
558 /// GetFunctionSizeInBytes - Returns the size of the specified
561 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0;
563 /// Measure the specified inline asm to determine an approximation of its
565 virtual unsigned getInlineAsmLength(const char *Str,
566 const MCAsmInfo &MAI) const;
569 /// TargetInstrInfoImpl - This is the default implementation of
570 /// TargetInstrInfo, which just provides a couple of default implementations
571 /// for various methods. This separated out because it is implemented in
572 /// libcodegen, not in libtarget.
573 class TargetInstrInfoImpl : public TargetInstrInfo {
575 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes)
576 : TargetInstrInfo(desc, NumOpcodes) {}
578 virtual MachineInstr *commuteInstruction(MachineInstr *MI,
579 bool NewMI = false) const;
580 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
581 unsigned &SrcOpIdx2) const;
582 virtual bool PredicateInstruction(MachineInstr *MI,
583 const SmallVectorImpl<MachineOperand> &Pred) const;
584 virtual void reMaterialize(MachineBasicBlock &MBB,
585 MachineBasicBlock::iterator MI,
586 unsigned DestReg, unsigned SubReg,
587 const MachineInstr *Orig,
588 const TargetRegisterInfo *TRI) const;
589 virtual MachineInstr *duplicate(MachineInstr *Orig,
590 MachineFunction &MF) const;
591 virtual bool isIdentical(const MachineInstr *MI,
592 const MachineInstr *Other,
593 const MachineRegisterInfo *MRI) const;
595 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const;
598 } // End llvm namespace