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;
30 template<class T> class SmallVectorImpl;
33 //---------------------------------------------------------------------------
35 /// TargetInstrInfo - Interface to description of machine instruction set
37 class TargetInstrInfo {
38 const TargetInstrDesc *Descriptors; // Raw array to allow static init'n
39 unsigned NumOpcodes; // Number of entries in the desc array
41 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
42 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
44 TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes);
45 virtual ~TargetInstrInfo();
47 // Invariant opcodes: All instruction sets have these as their low opcodes.
55 /// KILL - This instruction is a noop that is used only to adjust the liveness
56 /// of registers. This can be useful when dealing with sub-registers.
59 /// EXTRACT_SUBREG - This instruction takes two operands: a register
60 /// that has subregisters, and a subregister index. It returns the
61 /// extracted subregister value. This is commonly used to implement
62 /// truncation operations on target architectures which support it.
65 /// INSERT_SUBREG - This instruction takes three operands: a register
66 /// that has subregisters, a register providing an insert value, and a
67 /// subregister index. It returns the value of the first register with
68 /// the value of the second register inserted. The first register is
69 /// often defined by an IMPLICIT_DEF, as is commonly used to implement
70 /// anyext operations on target architectures which support it.
73 /// IMPLICIT_DEF - This is the MachineInstr-level equivalent of undef.
76 /// SUBREG_TO_REG - This instruction is similar to INSERT_SUBREG except
77 /// that the first operand is an immediate integer constant. This constant
78 /// is often zero, as is commonly used to implement zext operations on
79 /// target architectures which support it, such as with x86-64 (with
80 /// zext from i32 to i64 via implicit zero-extension).
83 /// COPY_TO_REGCLASS - This instruction is a placeholder for a plain
84 /// register-to-register copy into a specific register class. This is only
85 /// used between instruction selection and MachineInstr creation, before
86 /// virtual registers have been created for all the instructions, and it's
87 /// only needed in cases where the register classes implied by the
88 /// instructions are insufficient. The actual MachineInstrs to perform
89 /// the copy are emitted with the TargetInstrInfo::copyRegToReg hook.
93 unsigned getNumOpcodes() const { return NumOpcodes; }
95 /// get - Return the machine instruction descriptor that corresponds to the
96 /// specified instruction opcode.
98 const TargetInstrDesc &get(unsigned Opcode) const {
99 assert(Opcode < NumOpcodes && "Invalid opcode!");
100 return Descriptors[Opcode];
103 /// isTriviallyReMaterializable - Return true if the instruction is trivially
104 /// rematerializable, meaning it has no side effects and requires no operands
105 /// that aren't always available.
106 bool isTriviallyReMaterializable(const MachineInstr *MI,
107 AliasAnalysis *AA = 0) const {
108 return MI->getOpcode() == IMPLICIT_DEF ||
109 (MI->getDesc().isRematerializable() &&
110 (isReallyTriviallyReMaterializable(MI, AA) ||
111 isReallyTriviallyReMaterializableGeneric(MI, AA)));
115 /// isReallyTriviallyReMaterializable - For instructions with opcodes for
116 /// which the M_REMATERIALIZABLE flag is set, this hook lets the target
117 /// specify whether the instruction is actually trivially rematerializable,
118 /// taking into consideration its operands. This predicate must return false
119 /// if the instruction has any side effects other than producing a value, or
120 /// if it requres any address registers that are not always available.
121 virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
122 AliasAnalysis *AA) const {
127 /// isReallyTriviallyReMaterializableGeneric - For instructions with opcodes
128 /// for which the M_REMATERIALIZABLE flag is set and the target hook
129 /// isReallyTriviallyReMaterializable returns false, this function does
130 /// target-independent tests to determine if the instruction is really
131 /// trivially rematerializable.
132 bool isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
133 AliasAnalysis *AA) const;
136 /// isMoveInstr - Return true if the instruction is a register to register
137 /// move and return the source and dest operands and their sub-register
138 /// indices by reference.
139 virtual bool isMoveInstr(const MachineInstr& MI,
140 unsigned& SrcReg, unsigned& DstReg,
141 unsigned& SrcSubIdx, unsigned& DstSubIdx) const {
145 /// isIdentityCopy - Return true if the instruction is a copy (or
146 /// extract_subreg, insert_subreg, subreg_to_reg) where the source and
147 /// destination registers are the same.
148 bool isIdentityCopy(const MachineInstr &MI,
149 unsigned &SrcReg, unsigned &DstReg,
150 unsigned &SrcSubIdx, unsigned &DstSubIdx) const {
151 if (isMoveInstr(MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
155 if (MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
156 DstReg = MI.getOperand(0).getReg();
157 DstSubIdx = MI.getOperand(0).getSubReg();
158 SrcReg = MI.getOperand(1).getReg();
159 SrcSubIdx = MI.getOperand(1).getSubReg();
160 return DstReg == SrcReg;
163 if (MI.getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
164 MI.getOpcode() == TargetInstrInfo::SUBREG_TO_REG) {
165 DstReg = MI.getOperand(0).getReg();
166 DstSubIdx = MI.getOperand(0).getSubReg();
167 SrcReg = MI.getOperand(2).getReg();
168 SrcSubIdx = MI.getOperand(2).getSubReg();
169 return DstReg == SrcReg;
175 /// isLoadFromStackSlot - If the specified machine instruction is a direct
176 /// load from a stack slot, return the virtual or physical register number of
177 /// the destination along with the FrameIndex of the loaded stack slot. If
178 /// not, return 0. This predicate must return 0 if the instruction has
179 /// any side effects other than loading from the stack slot.
180 virtual unsigned isLoadFromStackSlot(const MachineInstr *MI,
181 int &FrameIndex) const {
185 /// isStoreToStackSlot - If the specified machine instruction is a direct
186 /// store to a stack slot, return the virtual or physical register number of
187 /// the source reg along with the FrameIndex of the loaded stack slot. If
188 /// not, return 0. This predicate must return 0 if the instruction has
189 /// any side effects other than storing to the stack slot.
190 virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
191 int &FrameIndex) const {
195 /// reMaterialize - Re-issue the specified 'original' instruction at the
196 /// specific location targeting a new destination register.
197 virtual void reMaterialize(MachineBasicBlock &MBB,
198 MachineBasicBlock::iterator MI,
199 unsigned DestReg, unsigned SubIdx,
200 const MachineInstr *Orig) const = 0;
202 /// convertToThreeAddress - This method must be implemented by targets that
203 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
204 /// may be able to convert a two-address instruction into one or more true
205 /// three-address instructions on demand. This allows the X86 target (for
206 /// example) to convert ADD and SHL instructions into LEA instructions if they
207 /// would require register copies due to two-addressness.
209 /// This method returns a null pointer if the transformation cannot be
210 /// performed, otherwise it returns the last new instruction.
212 virtual MachineInstr *
213 convertToThreeAddress(MachineFunction::iterator &MFI,
214 MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const {
218 /// commuteInstruction - If a target has any instructions that are commutable,
219 /// but require converting to a different instruction or making non-trivial
220 /// changes to commute them, this method can overloaded to do this. The
221 /// default implementation of this method simply swaps the first two operands
222 /// of MI and returns it.
224 /// If a target wants to make more aggressive changes, they can construct and
225 /// return a new machine instruction. If an instruction cannot commute, it
226 /// can also return null.
228 /// If NewMI is true, then a new machine instruction must be created.
230 virtual MachineInstr *commuteInstruction(MachineInstr *MI,
231 bool NewMI = false) const = 0;
233 /// findCommutedOpIndices - If specified MI is commutable, return the two
234 /// operand indices that would swap value. Return true if the instruction
235 /// is not in a form which this routine understands.
236 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
237 unsigned &SrcOpIdx2) const = 0;
239 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
240 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't
241 /// implemented for a target). Upon success, this returns false and returns
242 /// with the following information in various cases:
244 /// 1. If this block ends with no branches (it just falls through to its succ)
245 /// just return false, leaving TBB/FBB null.
246 /// 2. If this block ends with only an unconditional branch, it sets TBB to be
247 /// the destination block.
248 /// 3. If this block ends with an conditional branch and it falls through to
249 /// a successor block, it sets TBB to be the branch destination block and
250 /// a list of operands that evaluate the condition. These
251 /// operands can be passed to other TargetInstrInfo methods to create new
253 /// 4. If this block ends with a conditional branch followed by an
254 /// unconditional branch, it returns the 'true' destination in TBB, the
255 /// 'false' destination in FBB, and a list of operands that evaluate the
256 /// condition. These operands can be passed to other TargetInstrInfo
257 /// methods to create new branches.
259 /// Note that RemoveBranch and InsertBranch must be implemented to support
260 /// cases where this method returns success.
262 /// If AllowModify is true, then this routine is allowed to modify the basic
263 /// block (e.g. delete instructions after the unconditional branch).
265 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
266 MachineBasicBlock *&FBB,
267 SmallVectorImpl<MachineOperand> &Cond,
268 bool AllowModify = false) const {
272 /// RemoveBranch - Remove the branching code at the end of the specific MBB.
273 /// This is only invoked in cases where AnalyzeBranch returns success. It
274 /// returns the number of instructions that were removed.
275 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
276 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
280 /// InsertBranch - Insert branch code into the end of the specified
281 /// MachineBasicBlock. The operands to this method are the same as those
282 /// returned by AnalyzeBranch. This is only invoked in cases where
283 /// AnalyzeBranch returns success. It returns the number of instructions
286 /// It is also invoked by tail merging to add unconditional branches in
287 /// cases where AnalyzeBranch doesn't apply because there was no original
288 /// branch to analyze. At least this much must be implemented, else tail
289 /// merging needs to be disabled.
290 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
291 MachineBasicBlock *FBB,
292 const SmallVectorImpl<MachineOperand> &Cond) const {
293 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
297 /// copyRegToReg - Emit instructions to copy between a pair of registers. It
298 /// returns false if the target does not how to copy between the specified
300 virtual bool copyRegToReg(MachineBasicBlock &MBB,
301 MachineBasicBlock::iterator MI,
302 unsigned DestReg, unsigned SrcReg,
303 const TargetRegisterClass *DestRC,
304 const TargetRegisterClass *SrcRC) const {
305 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!");
309 /// storeRegToStackSlot - Store the specified register of the given register
310 /// class to the specified stack frame index. The store instruction is to be
311 /// added to the given machine basic block before the specified machine
312 /// instruction. If isKill is true, the register operand is the last use and
313 /// must be marked kill.
314 virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
315 MachineBasicBlock::iterator MI,
316 unsigned SrcReg, bool isKill, int FrameIndex,
317 const TargetRegisterClass *RC) const {
318 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
321 /// loadRegFromStackSlot - Load the specified register of the given register
322 /// class from the specified stack frame index. The load instruction is to be
323 /// added to the given machine basic block before the specified machine
325 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
326 MachineBasicBlock::iterator MI,
327 unsigned DestReg, int FrameIndex,
328 const TargetRegisterClass *RC) const {
329 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
332 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
333 /// saved registers and returns true if it isn't possible / profitable to do
334 /// so by issuing a series of store instructions via
335 /// storeRegToStackSlot(). Returns false otherwise.
336 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
337 MachineBasicBlock::iterator MI,
338 const std::vector<CalleeSavedInfo> &CSI) const {
342 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee
343 /// saved registers and returns true if it isn't possible / profitable to do
344 /// so by issuing a series of load instructions via loadRegToStackSlot().
345 /// Returns false otherwise.
346 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
347 MachineBasicBlock::iterator MI,
348 const std::vector<CalleeSavedInfo> &CSI) const {
352 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack
353 /// slot into the specified machine instruction for the specified operand(s).
354 /// If this is possible, a new instruction is returned with the specified
355 /// operand folded, otherwise NULL is returned. The client is responsible for
356 /// removing the old instruction and adding the new one in the instruction
358 MachineInstr* foldMemoryOperand(MachineFunction &MF,
360 const SmallVectorImpl<unsigned> &Ops,
361 int FrameIndex) const;
363 /// foldMemoryOperand - Same as the previous version except it allows folding
364 /// of any load and store from / to any address, not just from a specific
366 MachineInstr* foldMemoryOperand(MachineFunction &MF,
368 const SmallVectorImpl<unsigned> &Ops,
369 MachineInstr* LoadMI) const;
372 /// foldMemoryOperandImpl - Target-dependent implementation for
373 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will
374 /// take care of adding a MachineMemOperand to the newly created instruction.
375 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
377 const SmallVectorImpl<unsigned> &Ops,
378 int FrameIndex) const {
382 /// foldMemoryOperandImpl - Target-dependent implementation for
383 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will
384 /// take care of adding a MachineMemOperand to the newly created instruction.
385 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
387 const SmallVectorImpl<unsigned> &Ops,
388 MachineInstr* LoadMI) const {
393 /// canFoldMemoryOperand - Returns true for the specified load / store if
394 /// folding is possible.
396 bool canFoldMemoryOperand(const MachineInstr *MI,
397 const SmallVectorImpl<unsigned> &Ops) const {
401 /// unfoldMemoryOperand - Separate a single instruction which folded a load or
402 /// a store or a load and a store into two or more instruction. If this is
403 /// possible, returns true as well as the new instructions by reference.
404 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
405 unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
406 SmallVectorImpl<MachineInstr*> &NewMIs) const{
410 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
411 SmallVectorImpl<SDNode*> &NewNodes) const {
415 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
416 /// instruction after load / store are unfolded from an instruction of the
417 /// specified opcode. It returns zero if the specified unfolding is not
419 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
420 bool UnfoldLoad, bool UnfoldStore) const {
424 /// BlockHasNoFallThrough - Return true if the specified block does not
425 /// fall-through into its successor block. This is primarily used when a
426 /// branch is unanalyzable. It is useful for things like unconditional
427 /// indirect branches (jump tables).
428 virtual bool BlockHasNoFallThrough(const MachineBasicBlock &MBB) const {
432 /// ReverseBranchCondition - Reverses the branch condition of the specified
433 /// condition list, returning false on success and true if it cannot be
436 bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
440 /// insertNoop - Insert a noop into the instruction stream at the specified
442 virtual void insertNoop(MachineBasicBlock &MBB,
443 MachineBasicBlock::iterator MI) const;
445 /// isPredicated - Returns true if the instruction is already predicated.
447 virtual bool isPredicated(const MachineInstr *MI) const {
451 /// isUnpredicatedTerminator - Returns true if the instruction is a
452 /// terminator instruction that has not been predicated.
453 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
455 /// PredicateInstruction - Convert the instruction into a predicated
456 /// instruction. It returns true if the operation was successful.
458 bool PredicateInstruction(MachineInstr *MI,
459 const SmallVectorImpl<MachineOperand> &Pred) const = 0;
461 /// SubsumesPredicate - Returns true if the first specified predicate
462 /// subsumes the second, e.g. GE subsumes GT.
464 bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1,
465 const SmallVectorImpl<MachineOperand> &Pred2) const {
469 /// DefinesPredicate - If the specified instruction defines any predicate
470 /// or condition code register(s) used for predication, returns true as well
471 /// as the definition predicate(s) by reference.
472 virtual bool DefinesPredicate(MachineInstr *MI,
473 std::vector<MachineOperand> &Pred) const {
477 /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
478 /// instruction that defines the specified register class.
479 virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const {
483 /// GetInstSize - Returns the size of the specified Instruction.
485 virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const {
486 assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!");
490 /// GetFunctionSizeInBytes - Returns the size of the specified
493 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0;
495 /// Measure the specified inline asm to determine an approximation of its
497 virtual unsigned getInlineAsmLength(const char *Str,
498 const MCAsmInfo &MAI) const;
501 /// TargetInstrInfoImpl - This is the default implementation of
502 /// TargetInstrInfo, which just provides a couple of default implementations
503 /// for various methods. This separated out because it is implemented in
504 /// libcodegen, not in libtarget.
505 class TargetInstrInfoImpl : public TargetInstrInfo {
507 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes)
508 : TargetInstrInfo(desc, NumOpcodes) {}
510 virtual MachineInstr *commuteInstruction(MachineInstr *MI,
511 bool NewMI = false) const;
512 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
513 unsigned &SrcOpIdx2) const;
514 virtual bool PredicateInstruction(MachineInstr *MI,
515 const SmallVectorImpl<MachineOperand> &Pred) const;
516 virtual void reMaterialize(MachineBasicBlock &MBB,
517 MachineBasicBlock::iterator MI,
518 unsigned DestReg, unsigned SubReg,
519 const MachineInstr *Orig) const;
520 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const;
523 } // End llvm namespace