TargetInstrInfo.h revision 4406604047423576e36657c7ede266ca42e79642
1//===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file describes the target machine instructions to the code generator. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_TARGET_TARGETINSTRINFO_H 15#define LLVM_TARGET_TARGETINSTRINFO_H 16 17#include "llvm/Target/TargetInstrDesc.h" 18#include "llvm/CodeGen/MachineFunction.h" 19 20namespace llvm { 21 22class TargetRegisterClass; 23class LiveVariables; 24class CalleeSavedInfo; 25class SDNode; 26class SelectionDAG; 27 28template<class T> class SmallVectorImpl; 29 30 31//--------------------------------------------------------------------------- 32/// 33/// TargetInstrInfo - Interface to description of machine instructions 34/// 35class TargetInstrInfo { 36 const TargetInstrDesc *Descriptors; // Raw array to allow static init'n 37 unsigned NumOpcodes; // Number of entries in the desc array 38 39 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT 40 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT 41public: 42 TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes); 43 virtual ~TargetInstrInfo(); 44 45 // Invariant opcodes: All instruction sets have these as their low opcodes. 46 enum { 47 PHI = 0, 48 INLINEASM = 1, 49 DBG_LABEL = 2, 50 EH_LABEL = 3, 51 GC_LABEL = 4, 52 DECLARE = 5, 53 EXTRACT_SUBREG = 6, 54 INSERT_SUBREG = 7, 55 IMPLICIT_DEF = 8, 56 SUBREG_TO_REG = 9 57 }; 58 59 unsigned getNumOpcodes() const { return NumOpcodes; } 60 61 /// get - Return the machine instruction descriptor that corresponds to the 62 /// specified instruction opcode. 63 /// 64 const TargetInstrDesc &get(unsigned Opcode) const { 65 assert(Opcode < NumOpcodes && "Invalid opcode!"); 66 return Descriptors[Opcode]; 67 } 68 69 /// isTriviallyReMaterializable - Return true if the instruction is trivially 70 /// rematerializable, meaning it has no side effects and requires no operands 71 /// that aren't always available. 72 bool isTriviallyReMaterializable(const MachineInstr *MI) const { 73 return MI->getDesc().isRematerializable() && 74 isReallyTriviallyReMaterializable(MI); 75 } 76 77protected: 78 /// isReallyTriviallyReMaterializable - For instructions with opcodes for 79 /// which the M_REMATERIALIZABLE flag is set, this function tests whether the 80 /// instruction itself is actually trivially rematerializable, considering 81 /// its operands. This is used for targets that have instructions that are 82 /// only trivially rematerializable for specific uses. This predicate must 83 /// return false if the instruction has any side effects other than 84 /// producing a value, or if it requres any address registers that are not 85 /// always available. 86 virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI) const { 87 return true; 88 } 89 90public: 91 /// Return true if the instruction is a register to register move 92 /// and leave the source and dest operands in the passed parameters. 93 virtual bool isMoveInstr(const MachineInstr& MI, 94 unsigned& sourceReg, 95 unsigned& destReg) const { 96 return false; 97 } 98 99 /// isLoadFromStackSlot - If the specified machine instruction is a direct 100 /// load from a stack slot, return the virtual or physical register number of 101 /// the destination along with the FrameIndex of the loaded stack slot. If 102 /// not, return 0. This predicate must return 0 if the instruction has 103 /// any side effects other than loading from the stack slot. 104 virtual unsigned isLoadFromStackSlot(MachineInstr *MI, int &FrameIndex) const{ 105 return 0; 106 } 107 108 /// isStoreToStackSlot - If the specified machine instruction is a direct 109 /// store to a stack slot, return the virtual or physical register number of 110 /// the source reg along with the FrameIndex of the loaded stack slot. If 111 /// not, return 0. This predicate must return 0 if the instruction has 112 /// any side effects other than storing to the stack slot. 113 virtual unsigned isStoreToStackSlot(MachineInstr *MI, int &FrameIndex) const { 114 return 0; 115 } 116 117 /// reMaterialize - Re-issue the specified 'original' instruction at the 118 /// specific location targeting a new destination register. 119 virtual void reMaterialize(MachineBasicBlock &MBB, 120 MachineBasicBlock::iterator MI, 121 unsigned DestReg, 122 const MachineInstr *Orig) const = 0; 123 124 /// isInvariantLoad - Return true if the specified instruction (which is 125 /// marked mayLoad) is loading from a location whose value is invariant across 126 /// the function. For example, loading a value from the constant pool or from 127 /// from the argument area of a function if it does not change. This should 128 /// only return true of *all* loads the instruction does are invariant (if it 129 /// does multiple loads). 130 virtual bool isInvariantLoad(MachineInstr *MI) const { 131 return false; 132 } 133 134 /// convertToThreeAddress - This method must be implemented by targets that 135 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target 136 /// may be able to convert a two-address instruction into one or more true 137 /// three-address instructions on demand. This allows the X86 target (for 138 /// example) to convert ADD and SHL instructions into LEA instructions if they 139 /// would require register copies due to two-addressness. 140 /// 141 /// This method returns a null pointer if the transformation cannot be 142 /// performed, otherwise it returns the last new instruction. 143 /// 144 virtual MachineInstr * 145 convertToThreeAddress(MachineFunction::iterator &MFI, 146 MachineBasicBlock::iterator &MBBI, LiveVariables &LV) const { 147 return 0; 148 } 149 150 /// commuteInstruction - If a target has any instructions that are commutable, 151 /// but require converting to a different instruction or making non-trivial 152 /// changes to commute them, this method can overloaded to do this. The 153 /// default implementation of this method simply swaps the first two operands 154 /// of MI and returns it. 155 /// 156 /// If a target wants to make more aggressive changes, they can construct and 157 /// return a new machine instruction. If an instruction cannot commute, it 158 /// can also return null. 159 /// 160 /// If NewMI is true, then a new machine instruction must be created. 161 /// 162 virtual MachineInstr *commuteInstruction(MachineInstr *MI, 163 bool NewMI = false) const = 0; 164 165 /// CommuteChangesDestination - Return true if commuting the specified 166 /// instruction will also changes the destination operand. Also return the 167 /// current operand index of the would be new destination register by 168 /// reference. This can happen when the commutable instruction is also a 169 /// two-address instruction. 170 virtual bool CommuteChangesDestination(MachineInstr *MI, 171 unsigned &OpIdx) const = 0; 172 173 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning 174 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't 175 /// implemented for a target). Upon success, this returns false and returns 176 /// with the following information in various cases: 177 /// 178 /// 1. If this block ends with no branches (it just falls through to its succ) 179 /// just return false, leaving TBB/FBB null. 180 /// 2. If this block ends with only an unconditional branch, it sets TBB to be 181 /// the destination block. 182 /// 3. If this block ends with an conditional branch and it falls through to 183 /// an successor block, it sets TBB to be the branch destination block and a 184 /// list of operands that evaluate the condition. These 185 /// operands can be passed to other TargetInstrInfo methods to create new 186 /// branches. 187 /// 4. If this block ends with an conditional branch and an unconditional 188 /// block, it returns the 'true' destination in TBB, the 'false' destination 189 /// in FBB, and a list of operands that evaluate the condition. These 190 /// operands can be passed to other TargetInstrInfo methods to create new 191 /// branches. 192 /// 193 /// Note that RemoveBranch and InsertBranch must be implemented to support 194 /// cases where this method returns success. 195 /// 196 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, 197 MachineBasicBlock *&FBB, 198 std::vector<MachineOperand> &Cond) const { 199 return true; 200 } 201 202 /// RemoveBranch - Remove the branching code at the end of the specific MBB. 203 /// this is only invoked in cases where AnalyzeBranch returns success. It 204 /// returns the number of instructions that were removed. 205 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const { 206 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!"); 207 return 0; 208 } 209 210 /// InsertBranch - Insert a branch into the end of the specified 211 /// MachineBasicBlock. This operands to this method are the same as those 212 /// returned by AnalyzeBranch. This is invoked in cases where AnalyzeBranch 213 /// returns success and when an unconditional branch (TBB is non-null, FBB is 214 /// null, Cond is empty) needs to be inserted. It returns the number of 215 /// instructions inserted. 216 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, 217 MachineBasicBlock *FBB, 218 const std::vector<MachineOperand> &Cond) const { 219 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!"); 220 return 0; 221 } 222 223 /// copyRegToReg - Add a copy between a pair of registers 224 virtual void copyRegToReg(MachineBasicBlock &MBB, 225 MachineBasicBlock::iterator MI, 226 unsigned DestReg, unsigned SrcReg, 227 const TargetRegisterClass *DestRC, 228 const TargetRegisterClass *SrcRC) const { 229 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!"); 230 } 231 232 virtual void storeRegToStackSlot(MachineBasicBlock &MBB, 233 MachineBasicBlock::iterator MI, 234 unsigned SrcReg, bool isKill, int FrameIndex, 235 const TargetRegisterClass *RC) const { 236 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!"); 237 } 238 239 virtual void storeRegToAddr(MachineFunction &MF, unsigned SrcReg, bool isKill, 240 SmallVectorImpl<MachineOperand> &Addr, 241 const TargetRegisterClass *RC, 242 SmallVectorImpl<MachineInstr*> &NewMIs) const { 243 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToAddr!"); 244 } 245 246 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB, 247 MachineBasicBlock::iterator MI, 248 unsigned DestReg, int FrameIndex, 249 const TargetRegisterClass *RC) const { 250 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!"); 251 } 252 253 virtual void loadRegFromAddr(MachineFunction &MF, unsigned DestReg, 254 SmallVectorImpl<MachineOperand> &Addr, 255 const TargetRegisterClass *RC, 256 SmallVectorImpl<MachineInstr*> &NewMIs) const { 257 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromAddr!"); 258 } 259 260 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee 261 /// saved registers and returns true if it isn't possible / profitable to do 262 /// so by issuing a series of store instructions via 263 /// storeRegToStackSlot(). Returns false otherwise. 264 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, 265 MachineBasicBlock::iterator MI, 266 const std::vector<CalleeSavedInfo> &CSI) const { 267 return false; 268 } 269 270 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee 271 /// saved registers and returns true if it isn't possible / profitable to do 272 /// so by issuing a series of load instructions via loadRegToStackSlot(). 273 /// Returns false otherwise. 274 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 275 MachineBasicBlock::iterator MI, 276 const std::vector<CalleeSavedInfo> &CSI) const { 277 return false; 278 } 279 280 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack 281 /// slot into the specified machine instruction for the specified operand(s). 282 /// If this is possible, a new instruction is returned with the specified 283 /// operand folded, otherwise NULL is returned. The client is responsible for 284 /// removing the old instruction and adding the new one in the instruction 285 /// stream. 286 virtual MachineInstr* foldMemoryOperand(MachineFunction &MF, 287 MachineInstr* MI, 288 SmallVectorImpl<unsigned> &Ops, 289 int FrameIndex) const { 290 return 0; 291 } 292 293 /// foldMemoryOperand - Same as the previous version except it allows folding 294 /// of any load and store from / to any address, not just from a specific 295 /// stack slot. 296 virtual MachineInstr* foldMemoryOperand(MachineFunction &MF, 297 MachineInstr* MI, 298 SmallVectorImpl<unsigned> &Ops, 299 MachineInstr* LoadMI) const { 300 return 0; 301 } 302 303 /// canFoldMemoryOperand - Returns true if the specified load / store is 304 /// folding is possible. 305 virtual 306 bool canFoldMemoryOperand(MachineInstr *MI, 307 SmallVectorImpl<unsigned> &Ops) const{ 308 return false; 309 } 310 311 /// unfoldMemoryOperand - Separate a single instruction which folded a load or 312 /// a store or a load and a store into two or more instruction. If this is 313 /// possible, returns true as well as the new instructions by reference. 314 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI, 315 unsigned Reg, bool UnfoldLoad, bool UnfoldStore, 316 SmallVectorImpl<MachineInstr*> &NewMIs) const{ 317 return false; 318 } 319 320 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N, 321 SmallVectorImpl<SDNode*> &NewNodes) const { 322 return false; 323 } 324 325 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new 326 /// instruction after load / store are unfolded from an instruction of the 327 /// specified opcode. It returns zero if the specified unfolding is not 328 /// possible. 329 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc, 330 bool UnfoldLoad, bool UnfoldStore) const { 331 return 0; 332 } 333 334 /// BlockHasNoFallThrough - Return true if the specified block does not 335 /// fall-through into its successor block. This is primarily used when a 336 /// branch is unanalyzable. It is useful for things like unconditional 337 /// indirect branches (jump tables). 338 virtual bool BlockHasNoFallThrough(MachineBasicBlock &MBB) const { 339 return false; 340 } 341 342 /// ReverseBranchCondition - Reverses the branch condition of the specified 343 /// condition list, returning false on success and true if it cannot be 344 /// reversed. 345 virtual bool ReverseBranchCondition(std::vector<MachineOperand> &Cond) const { 346 return true; 347 } 348 349 /// insertNoop - Insert a noop into the instruction stream at the specified 350 /// point. 351 virtual void insertNoop(MachineBasicBlock &MBB, 352 MachineBasicBlock::iterator MI) const { 353 assert(0 && "Target didn't implement insertNoop!"); 354 abort(); 355 } 356 357 /// isPredicated - Returns true if the instruction is already predicated. 358 /// 359 virtual bool isPredicated(const MachineInstr *MI) const { 360 return false; 361 } 362 363 /// isUnpredicatedTerminator - Returns true if the instruction is a 364 /// terminator instruction that has not been predicated. 365 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const; 366 367 /// PredicateInstruction - Convert the instruction into a predicated 368 /// instruction. It returns true if the operation was successful. 369 virtual 370 bool PredicateInstruction(MachineInstr *MI, 371 const std::vector<MachineOperand> &Pred) const = 0; 372 373 /// SubsumesPredicate - Returns true if the first specified predicate 374 /// subsumes the second, e.g. GE subsumes GT. 375 virtual 376 bool SubsumesPredicate(const std::vector<MachineOperand> &Pred1, 377 const std::vector<MachineOperand> &Pred2) const { 378 return false; 379 } 380 381 /// DefinesPredicate - If the specified instruction defines any predicate 382 /// or condition code register(s) used for predication, returns true as well 383 /// as the definition predicate(s) by reference. 384 virtual bool DefinesPredicate(MachineInstr *MI, 385 std::vector<MachineOperand> &Pred) const { 386 return false; 387 } 388 389 /// getPointerRegClass - Returns a TargetRegisterClass used for pointer 390 /// values. 391 virtual const TargetRegisterClass *getPointerRegClass() const { 392 assert(0 && "Target didn't implement getPointerRegClass!"); 393 abort(); 394 return 0; // Must return a value in order to compile with VS 2005 395 } 396 397 /// GetInstSize - Returns the size of the specified Instruction. 398 /// 399 virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const { 400 assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!"); 401 return 0; 402 } 403 404 /// GetFunctionSizeInBytes - Returns the size of the specified MachineFunction. 405 /// 406 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0; 407 408}; 409 410/// TargetInstrInfoImpl - This is the default implementation of 411/// TargetInstrInfo, which just provides a couple of default implementations 412/// for various methods. This separated out because it is implemented in 413/// libcodegen, not in libtarget. 414class TargetInstrInfoImpl : public TargetInstrInfo { 415protected: 416 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes) 417 : TargetInstrInfo(desc, NumOpcodes) {} 418public: 419 virtual MachineInstr *commuteInstruction(MachineInstr *MI, 420 bool NewMI = false) const; 421 virtual bool CommuteChangesDestination(MachineInstr *MI, 422 unsigned &OpIdx) const; 423 virtual bool PredicateInstruction(MachineInstr *MI, 424 const std::vector<MachineOperand> &Pred) const; 425 virtual void reMaterialize(MachineBasicBlock &MBB, 426 MachineBasicBlock::iterator MI, 427 unsigned DestReg, 428 const MachineInstr *Orig) const; 429 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const; 430}; 431 432} // End llvm namespace 433 434#endif 435