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 instructions 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"
22 class TargetRegisterClass;
24 class CalleeSavedInfo;
28 template<class T> class SmallVectorImpl;
31 //---------------------------------------------------------------------------
33 /// TargetInstrInfo - Interface to description of machine instructions
35 class TargetInstrInfo {
36 const TargetInstrDesc *Descriptors; // Raw array to allow static init'n
37 unsigned NumOpcodes; // Number of entries in the desc array
39 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
40 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
42 TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes);
43 virtual ~TargetInstrInfo();
45 // Invariant opcodes: All instruction sets have these as their low opcodes.
54 unsigned getNumOpcodes() const { return NumOpcodes; }
56 /// get - Return the machine instruction descriptor that corresponds to the
57 /// specified instruction opcode.
59 const TargetInstrDesc &get(unsigned Opcode) const {
60 assert(Opcode < NumOpcodes && "Invalid opcode!");
61 return Descriptors[Opcode];
64 /// isTriviallyReMaterializable - Return true if the instruction is trivially
65 /// rematerializable, meaning it has no side effects and requires no operands
66 /// that aren't always available.
67 bool isTriviallyReMaterializable(MachineInstr *MI) const {
68 return MI->getDesc().isRematerializable() &&
69 isReallyTriviallyReMaterializable(MI);
72 /// hasUnmodelledSideEffects - Returns true if the instruction has side
73 /// effects that are not captured by any operands of the instruction or other
75 bool hasUnmodelledSideEffects(MachineInstr *MI) const {
76 const TargetInstrDesc &TID = MI->getDesc();
77 if (TID.hasNoSideEffects()) return false;
78 if (!TID.hasConditionalSideEffects()) return true;
79 return !isReallySideEffectFree(MI); // May have side effects
82 /// isReallyTriviallyReMaterializable - For instructions with opcodes for
83 /// which the M_REMATERIALIZABLE flag is set, this function tests whether the
84 /// instruction itself is actually trivially rematerializable, considering
85 /// its operands. This is used for targets that have instructions that are
86 /// only trivially rematerializable for specific uses. This predicate must
87 /// return false if the instruction has any side effects other than
88 /// producing a value, or if it requres any address registers that are not
90 virtual bool isReallyTriviallyReMaterializable(MachineInstr *MI) const {
94 /// isReallySideEffectFree - If the M_MAY_HAVE_SIDE_EFFECTS flag is set, this
95 /// method is called to determine if the specific instance of this
96 /// instruction has side effects. This is useful in cases of instructions,
97 /// like loads, which generally always have side effects. A load from a
98 /// constant pool doesn't have side effects, though. So we need to
99 /// differentiate it from the general case.
100 virtual bool isReallySideEffectFree(MachineInstr *MI) const {
104 /// Return true if the instruction is a register to register move
105 /// and leave the source and dest operands in the passed parameters.
106 virtual bool isMoveInstr(const MachineInstr& MI,
108 unsigned& destReg) const {
112 /// isLoadFromStackSlot - If the specified machine instruction is a direct
113 /// load from a stack slot, return the virtual or physical register number of
114 /// the destination along with the FrameIndex of the loaded stack slot. If
115 /// not, return 0. This predicate must return 0 if the instruction has
116 /// any side effects other than loading from the stack slot.
117 virtual unsigned isLoadFromStackSlot(MachineInstr *MI, int &FrameIndex) const{
121 /// isStoreToStackSlot - If the specified machine instruction is a direct
122 /// store to a stack slot, return the virtual or physical register number of
123 /// the source reg along with the FrameIndex of the loaded stack slot. If
124 /// not, return 0. This predicate must return 0 if the instruction has
125 /// any side effects other than storing to the stack slot.
126 virtual unsigned isStoreToStackSlot(MachineInstr *MI, int &FrameIndex) const {
130 /// convertToThreeAddress - This method must be implemented by targets that
131 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
132 /// may be able to convert a two-address instruction into one or more true
133 /// three-address instructions on demand. This allows the X86 target (for
134 /// example) to convert ADD and SHL instructions into LEA instructions if they
135 /// would require register copies due to two-addressness.
137 /// This method returns a null pointer if the transformation cannot be
138 /// performed, otherwise it returns the last new instruction.
140 virtual MachineInstr *
141 convertToThreeAddress(MachineFunction::iterator &MFI,
142 MachineBasicBlock::iterator &MBBI, LiveVariables &LV) const {
146 /// commuteInstruction - If a target has any instructions that are commutable,
147 /// but require converting to a different instruction or making non-trivial
148 /// changes to commute them, this method can overloaded to do this. The
149 /// default implementation of this method simply swaps the first two operands
150 /// of MI and returns it.
152 /// If a target wants to make more aggressive changes, they can construct and
153 /// return a new machine instruction. If an instruction cannot commute, it
154 /// can also return null.
156 virtual MachineInstr *commuteInstruction(MachineInstr *MI) const = 0;
158 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
159 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't
160 /// implemented for a target). Upon success, this returns false and returns
161 /// with the following information in various cases:
163 /// 1. If this block ends with no branches (it just falls through to its succ)
164 /// just return false, leaving TBB/FBB null.
165 /// 2. If this block ends with only an unconditional branch, it sets TBB to be
166 /// the destination block.
167 /// 3. If this block ends with an conditional branch and it falls through to
168 /// an successor block, it sets TBB to be the branch destination block and a
169 /// list of operands that evaluate the condition. These
170 /// operands can be passed to other TargetInstrInfo methods to create new
172 /// 4. If this block ends with an conditional branch and an unconditional
173 /// block, it returns the 'true' destination in TBB, the 'false' destination
174 /// in FBB, and a list of operands that evaluate the condition. These
175 /// operands can be passed to other TargetInstrInfo methods to create new
178 /// Note that RemoveBranch and InsertBranch must be implemented to support
179 /// cases where this method returns success.
181 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
182 MachineBasicBlock *&FBB,
183 std::vector<MachineOperand> &Cond) const {
187 /// RemoveBranch - Remove the branching code at the end of the specific MBB.
188 /// this is only invoked in cases where AnalyzeBranch returns success. It
189 /// returns the number of instructions that were removed.
190 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
191 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
195 /// InsertBranch - Insert a branch into the end of the specified
196 /// MachineBasicBlock. This operands to this method are the same as those
197 /// returned by AnalyzeBranch. This is invoked in cases where AnalyzeBranch
198 /// returns success and when an unconditional branch (TBB is non-null, FBB is
199 /// null, Cond is empty) needs to be inserted. It returns the number of
200 /// instructions inserted.
201 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
202 MachineBasicBlock *FBB,
203 const std::vector<MachineOperand> &Cond) const {
204 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
208 /// copyRegToReg - Add a copy between a pair of registers
209 virtual void copyRegToReg(MachineBasicBlock &MBB,
210 MachineBasicBlock::iterator MI,
211 unsigned DestReg, unsigned SrcReg,
212 const TargetRegisterClass *DestRC,
213 const TargetRegisterClass *SrcRC) const {
214 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!");
217 virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
218 MachineBasicBlock::iterator MI,
219 unsigned SrcReg, bool isKill, int FrameIndex,
220 const TargetRegisterClass *RC) const {
221 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
224 virtual void storeRegToAddr(MachineFunction &MF, unsigned SrcReg, bool isKill,
225 SmallVectorImpl<MachineOperand> &Addr,
226 const TargetRegisterClass *RC,
227 SmallVectorImpl<MachineInstr*> &NewMIs) const {
228 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToAddr!");
231 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
232 MachineBasicBlock::iterator MI,
233 unsigned DestReg, int FrameIndex,
234 const TargetRegisterClass *RC) const {
235 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
238 virtual void loadRegFromAddr(MachineFunction &MF, unsigned DestReg,
239 SmallVectorImpl<MachineOperand> &Addr,
240 const TargetRegisterClass *RC,
241 SmallVectorImpl<MachineInstr*> &NewMIs) const {
242 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromAddr!");
245 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
246 /// saved registers and returns true if it isn't possible / profitable to do
247 /// so by issuing a series of store instructions via
248 /// storeRegToStackSlot(). Returns false otherwise.
249 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
250 MachineBasicBlock::iterator MI,
251 const std::vector<CalleeSavedInfo> &CSI) const {
255 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee
256 /// saved registers and returns true if it isn't possible / profitable to do
257 /// so by issuing a series of load instructions via loadRegToStackSlot().
258 /// Returns false otherwise.
259 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
260 MachineBasicBlock::iterator MI,
261 const std::vector<CalleeSavedInfo> &CSI) const {
265 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack
266 /// slot into the specified machine instruction for the specified operand(s).
267 /// If this is possible, a new instruction is returned with the specified
268 /// operand folded, otherwise NULL is returned. The client is responsible for
269 /// removing the old instruction and adding the new one in the instruction
271 virtual MachineInstr* foldMemoryOperand(MachineInstr* MI,
272 SmallVectorImpl<unsigned> &Ops,
273 int FrameIndex) const {
277 /// foldMemoryOperand - Same as the previous version except it allows folding
278 /// of any load and store from / to any address, not just from a specific
280 virtual MachineInstr* foldMemoryOperand(MachineInstr* MI,
281 SmallVectorImpl<unsigned> &Ops,
282 MachineInstr* LoadMI) const {
286 /// canFoldMemoryOperand - Returns true if the specified load / store is
287 /// folding is possible.
289 bool canFoldMemoryOperand(MachineInstr *MI,
290 SmallVectorImpl<unsigned> &Ops) const{
294 /// unfoldMemoryOperand - Separate a single instruction which folded a load or
295 /// a store or a load and a store into two or more instruction. If this is
296 /// possible, returns true as well as the new instructions by reference.
297 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
298 unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
299 SmallVectorImpl<MachineInstr*> &NewMIs) const{
303 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
304 SmallVectorImpl<SDNode*> &NewNodes) const {
308 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
309 /// instruction after load / store are unfolded from an instruction of the
310 /// specified opcode. It returns zero if the specified unfolding is not
312 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
313 bool UnfoldLoad, bool UnfoldStore) const {
317 /// BlockHasNoFallThrough - Return true if the specified block does not
318 /// fall-through into its successor block. This is primarily used when a
319 /// branch is unanalyzable. It is useful for things like unconditional
320 /// indirect branches (jump tables).
321 virtual bool BlockHasNoFallThrough(MachineBasicBlock &MBB) const {
325 /// ReverseBranchCondition - Reverses the branch condition of the specified
326 /// condition list, returning false on success and true if it cannot be
328 virtual bool ReverseBranchCondition(std::vector<MachineOperand> &Cond) const {
332 /// insertNoop - Insert a noop into the instruction stream at the specified
334 virtual void insertNoop(MachineBasicBlock &MBB,
335 MachineBasicBlock::iterator MI) const {
336 assert(0 && "Target didn't implement insertNoop!");
340 /// isPredicated - Returns true if the instruction is already predicated.
342 virtual bool isPredicated(const MachineInstr *MI) const {
346 /// isUnpredicatedTerminator - Returns true if the instruction is a
347 /// terminator instruction that has not been predicated.
348 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
350 /// PredicateInstruction - Convert the instruction into a predicated
351 /// instruction. It returns true if the operation was successful.
353 bool PredicateInstruction(MachineInstr *MI,
354 const std::vector<MachineOperand> &Pred) const = 0;
356 /// SubsumesPredicate - Returns true if the first specified predicate
357 /// subsumes the second, e.g. GE subsumes GT.
359 bool SubsumesPredicate(const std::vector<MachineOperand> &Pred1,
360 const std::vector<MachineOperand> &Pred2) const {
364 /// DefinesPredicate - If the specified instruction defines any predicate
365 /// or condition code register(s) used for predication, returns true as well
366 /// as the definition predicate(s) by reference.
367 virtual bool DefinesPredicate(MachineInstr *MI,
368 std::vector<MachineOperand> &Pred) const {
372 /// getPointerRegClass - Returns a TargetRegisterClass used for pointer
374 virtual const TargetRegisterClass *getPointerRegClass() const {
375 assert(0 && "Target didn't implement getPointerRegClass!");
377 return 0; // Must return a value in order to compile with VS 2005
381 /// TargetInstrInfoImpl - This is the default implementation of
382 /// TargetInstrInfo, which just provides a couple of default implementations
383 /// for various methods. This separated out because it is implemented in
384 /// libcodegen, not in libtarget.
385 class TargetInstrInfoImpl : public TargetInstrInfo {
387 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes)
388 : TargetInstrInfo(desc, NumOpcodes) {}
390 virtual MachineInstr *commuteInstruction(MachineInstr *MI) const;
391 virtual bool PredicateInstruction(MachineInstr *MI,
392 const std::vector<MachineOperand> &Pred) const;
396 } // End llvm namespace