TargetInstrInfo.h revision dc54d317e7a381ef8e4aca80d54ad1466bb85dda
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 instruction set 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 instruction set 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 and return 92 /// the source and dest operands and their sub-register indices by reference. 93 virtual bool isMoveInstr(const MachineInstr& MI, 94 unsigned& SrcReg, unsigned& DstReg, 95 unsigned& SrcSubIdx, unsigned& DstSubIdx) 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(const MachineInstr *MI, 105 int &FrameIndex) const { 106 return 0; 107 } 108 109 /// isStoreToStackSlot - If the specified machine instruction is a direct 110 /// store to a stack slot, return the virtual or physical register number of 111 /// the source reg along with the FrameIndex of the loaded stack slot. If 112 /// not, return 0. This predicate must return 0 if the instruction has 113 /// any side effects other than storing to the stack slot. 114 virtual unsigned isStoreToStackSlot(const MachineInstr *MI, 115 int &FrameIndex) const { 116 return 0; 117 } 118 119 /// reMaterialize - Re-issue the specified 'original' instruction at the 120 /// specific location targeting a new destination register. 121 virtual void reMaterialize(MachineBasicBlock &MBB, 122 MachineBasicBlock::iterator MI, 123 unsigned DestReg, 124 const MachineInstr *Orig) const = 0; 125 126 /// isInvariantLoad - Return true if the specified instruction (which is 127 /// marked mayLoad) is loading from a location whose value is invariant across 128 /// the function. For example, loading a value from the constant pool or from 129 /// from the argument area of a function if it does not change. This should 130 /// only return true of *all* loads the instruction does are invariant (if it 131 /// does multiple loads). 132 virtual bool isInvariantLoad(const MachineInstr *MI) const { 133 return false; 134 } 135 136 /// convertToThreeAddress - This method must be implemented by targets that 137 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target 138 /// may be able to convert a two-address instruction into one or more true 139 /// three-address instructions on demand. This allows the X86 target (for 140 /// example) to convert ADD and SHL instructions into LEA instructions if they 141 /// would require register copies due to two-addressness. 142 /// 143 /// This method returns a null pointer if the transformation cannot be 144 /// performed, otherwise it returns the last new instruction. 145 /// 146 virtual MachineInstr * 147 convertToThreeAddress(MachineFunction::iterator &MFI, 148 MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const { 149 return 0; 150 } 151 152 /// commuteInstruction - If a target has any instructions that are commutable, 153 /// but require converting to a different instruction or making non-trivial 154 /// changes to commute them, this method can overloaded to do this. The 155 /// default implementation of this method simply swaps the first two operands 156 /// of MI and returns it. 157 /// 158 /// If a target wants to make more aggressive changes, they can construct and 159 /// return a new machine instruction. If an instruction cannot commute, it 160 /// can also return null. 161 /// 162 /// If NewMI is true, then a new machine instruction must be created. 163 /// 164 virtual MachineInstr *commuteInstruction(MachineInstr *MI, 165 bool NewMI = false) const = 0; 166 167 /// CommuteChangesDestination - Return true if commuting the specified 168 /// instruction will also changes the destination operand. Also return the 169 /// current operand index of the would be new destination register by 170 /// reference. This can happen when the commutable instruction is also a 171 /// two-address instruction. 172 virtual bool CommuteChangesDestination(MachineInstr *MI, 173 unsigned &OpIdx) const = 0; 174 175 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning 176 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't 177 /// implemented for a target). Upon success, this returns false and returns 178 /// with the following information in various cases: 179 /// 180 /// 1. If this block ends with no branches (it just falls through to its succ) 181 /// just return false, leaving TBB/FBB null. 182 /// 2. If this block ends with only an unconditional branch, it sets TBB to be 183 /// the destination block. 184 /// 3. If this block ends with an conditional branch and it falls through to 185 /// an successor block, it sets TBB to be the branch destination block and a 186 /// list of operands that evaluate the condition. These 187 /// operands can be passed to other TargetInstrInfo methods to create new 188 /// branches. 189 /// 4. If this block ends with an conditional branch and an unconditional 190 /// block, it returns the 'true' destination in TBB, the 'false' destination 191 /// in FBB, and a list of operands that evaluate the condition. These 192 /// operands can be passed to other TargetInstrInfo methods to create new 193 /// branches. 194 /// 195 /// Note that RemoveBranch and InsertBranch must be implemented to support 196 /// cases where this method returns success. 197 /// 198 /// If AllowModify is true, then this routine is allowed to modify the basic 199 /// block (e.g. delete instructions after the unconditional branch). 200 /// 201 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, 202 MachineBasicBlock *&FBB, 203 SmallVectorImpl<MachineOperand> &Cond, 204 bool AllowModify = false) const { 205 return true; 206 } 207 208 /// RemoveBranch - Remove the branching code at the end of the specific MBB. 209 /// This is only invoked in cases where AnalyzeBranch returns success. It 210 /// returns the number of instructions that were removed. 211 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const { 212 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!"); 213 return 0; 214 } 215 216 /// InsertBranch - Insert a branch into the end of the specified 217 /// MachineBasicBlock. This operands to this method are the same as those 218 /// returned by AnalyzeBranch. This is invoked in cases where AnalyzeBranch 219 /// returns success and when an unconditional branch (TBB is non-null, FBB is 220 /// null, Cond is empty) needs to be inserted. It returns the number of 221 /// instructions inserted. 222 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, 223 MachineBasicBlock *FBB, 224 const SmallVectorImpl<MachineOperand> &Cond) const { 225 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!"); 226 return 0; 227 } 228 229 /// copyRegToReg - Emit instructions to copy between a pair of registers. It 230 /// returns false if the target does not how to copy between the specified 231 /// registers. 232 virtual bool copyRegToReg(MachineBasicBlock &MBB, 233 MachineBasicBlock::iterator MI, 234 unsigned DestReg, unsigned SrcReg, 235 const TargetRegisterClass *DestRC, 236 const TargetRegisterClass *SrcRC) const { 237 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!"); 238 return false; 239 } 240 241 /// storeRegToStackSlot - Store the specified register of the given register 242 /// class to the specified stack frame index. The store instruction is to be 243 /// added to the given machine basic block before the specified machine 244 /// instruction. If isKill is true, the register operand is the last use and 245 /// must be marked kill. 246 virtual void storeRegToStackSlot(MachineBasicBlock &MBB, 247 MachineBasicBlock::iterator MI, 248 unsigned SrcReg, bool isKill, int FrameIndex, 249 const TargetRegisterClass *RC) const { 250 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!"); 251 } 252 253 /// storeRegToAddr - Store the specified register of the given register class 254 /// to the specified address. The store instruction is to be added to the 255 /// given machine basic block before the specified machine instruction. If 256 /// isKill is true, the register operand is the last use and must be marked 257 /// kill. 258 virtual void storeRegToAddr(MachineFunction &MF, unsigned SrcReg, bool isKill, 259 SmallVectorImpl<MachineOperand> &Addr, 260 const TargetRegisterClass *RC, 261 SmallVectorImpl<MachineInstr*> &NewMIs) const { 262 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToAddr!"); 263 } 264 265 /// loadRegFromStackSlot - Load the specified register of the given register 266 /// class from the specified stack frame index. The load instruction is to be 267 /// added to the given machine basic block before the specified machine 268 /// instruction. 269 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB, 270 MachineBasicBlock::iterator MI, 271 unsigned DestReg, int FrameIndex, 272 const TargetRegisterClass *RC) const { 273 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!"); 274 } 275 276 /// loadRegFromAddr - Load the specified register of the given register class 277 /// class from the specified address. The load instruction is to be added to 278 /// the given machine basic block before the specified machine instruction. 279 virtual void loadRegFromAddr(MachineFunction &MF, unsigned DestReg, 280 SmallVectorImpl<MachineOperand> &Addr, 281 const TargetRegisterClass *RC, 282 SmallVectorImpl<MachineInstr*> &NewMIs) const { 283 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromAddr!"); 284 } 285 286 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee 287 /// saved registers and returns true if it isn't possible / profitable to do 288 /// so by issuing a series of store instructions via 289 /// storeRegToStackSlot(). Returns false otherwise. 290 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, 291 MachineBasicBlock::iterator MI, 292 const std::vector<CalleeSavedInfo> &CSI) const { 293 return false; 294 } 295 296 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee 297 /// saved registers and returns true if it isn't possible / profitable to do 298 /// so by issuing a series of load instructions via loadRegToStackSlot(). 299 /// Returns false otherwise. 300 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 301 MachineBasicBlock::iterator MI, 302 const std::vector<CalleeSavedInfo> &CSI) const { 303 return false; 304 } 305 306 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack 307 /// slot into the specified machine instruction for the specified operand(s). 308 /// If this is possible, a new instruction is returned with the specified 309 /// operand folded, otherwise NULL is returned. The client is responsible for 310 /// removing the old instruction and adding the new one in the instruction 311 /// stream. 312 MachineInstr* foldMemoryOperand(MachineFunction &MF, 313 MachineInstr* MI, 314 const SmallVectorImpl<unsigned> &Ops, 315 int FrameIndex) const; 316 317 /// foldMemoryOperand - Same as the previous version except it allows folding 318 /// of any load and store from / to any address, not just from a specific 319 /// stack slot. 320 MachineInstr* foldMemoryOperand(MachineFunction &MF, 321 MachineInstr* MI, 322 const SmallVectorImpl<unsigned> &Ops, 323 MachineInstr* LoadMI) const; 324 325protected: 326 /// foldMemoryOperandImpl - Target-dependent implementation for 327 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will 328 /// take care of adding a MachineMemOperand to the newly created instruction. 329 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF, 330 MachineInstr* MI, 331 const SmallVectorImpl<unsigned> &Ops, 332 int FrameIndex) const { 333 return 0; 334 } 335 336 /// foldMemoryOperandImpl - Target-dependent implementation for 337 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will 338 /// take care of adding a MachineMemOperand to the newly created instruction. 339 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF, 340 MachineInstr* MI, 341 const SmallVectorImpl<unsigned> &Ops, 342 MachineInstr* LoadMI) const { 343 return 0; 344 } 345 346public: 347 /// canFoldMemoryOperand - Returns true for the specified load / store if 348 /// folding is possible. 349 virtual 350 bool canFoldMemoryOperand(const MachineInstr *MI, 351 const SmallVectorImpl<unsigned> &Ops) const { 352 return false; 353 } 354 355 /// unfoldMemoryOperand - Separate a single instruction which folded a load or 356 /// a store or a load and a store into two or more instruction. If this is 357 /// possible, returns true as well as the new instructions by reference. 358 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI, 359 unsigned Reg, bool UnfoldLoad, bool UnfoldStore, 360 SmallVectorImpl<MachineInstr*> &NewMIs) const{ 361 return false; 362 } 363 364 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N, 365 SmallVectorImpl<SDNode*> &NewNodes) const { 366 return false; 367 } 368 369 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new 370 /// instruction after load / store are unfolded from an instruction of the 371 /// specified opcode. It returns zero if the specified unfolding is not 372 /// possible. 373 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc, 374 bool UnfoldLoad, bool UnfoldStore) const { 375 return 0; 376 } 377 378 /// BlockHasNoFallThrough - Return true if the specified block does not 379 /// fall-through into its successor block. This is primarily used when a 380 /// branch is unanalyzable. It is useful for things like unconditional 381 /// indirect branches (jump tables). 382 virtual bool BlockHasNoFallThrough(const MachineBasicBlock &MBB) const { 383 return false; 384 } 385 386 /// ReverseBranchCondition - Reverses the branch condition of the specified 387 /// condition list, returning false on success and true if it cannot be 388 /// reversed. 389 virtual 390 bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const { 391 return true; 392 } 393 394 /// insertNoop - Insert a noop into the instruction stream at the specified 395 /// point. 396 virtual void insertNoop(MachineBasicBlock &MBB, 397 MachineBasicBlock::iterator MI) const { 398 assert(0 && "Target didn't implement insertNoop!"); 399 abort(); 400 } 401 402 /// isPredicated - Returns true if the instruction is already predicated. 403 /// 404 virtual bool isPredicated(const MachineInstr *MI) const { 405 return false; 406 } 407 408 /// isUnpredicatedTerminator - Returns true if the instruction is a 409 /// terminator instruction that has not been predicated. 410 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const; 411 412 /// PredicateInstruction - Convert the instruction into a predicated 413 /// instruction. It returns true if the operation was successful. 414 virtual 415 bool PredicateInstruction(MachineInstr *MI, 416 const SmallVectorImpl<MachineOperand> &Pred) const = 0; 417 418 /// SubsumesPredicate - Returns true if the first specified predicate 419 /// subsumes the second, e.g. GE subsumes GT. 420 virtual 421 bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1, 422 const SmallVectorImpl<MachineOperand> &Pred2) const { 423 return false; 424 } 425 426 /// DefinesPredicate - If the specified instruction defines any predicate 427 /// or condition code register(s) used for predication, returns true as well 428 /// as the definition predicate(s) by reference. 429 virtual bool DefinesPredicate(MachineInstr *MI, 430 std::vector<MachineOperand> &Pred) const { 431 return false; 432 } 433 434 /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine 435 /// instruction that defines the specified register class. 436 virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const { 437 return true; 438 } 439 440 /// GetInstSize - Returns the size of the specified Instruction. 441 /// 442 virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const { 443 assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!"); 444 return 0; 445 } 446 447 /// GetFunctionSizeInBytes - Returns the size of the specified MachineFunction. 448 /// 449 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0; 450}; 451 452/// TargetInstrInfoImpl - This is the default implementation of 453/// TargetInstrInfo, which just provides a couple of default implementations 454/// for various methods. This separated out because it is implemented in 455/// libcodegen, not in libtarget. 456class TargetInstrInfoImpl : public TargetInstrInfo { 457protected: 458 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes) 459 : TargetInstrInfo(desc, NumOpcodes) {} 460public: 461 virtual MachineInstr *commuteInstruction(MachineInstr *MI, 462 bool NewMI = false) const; 463 virtual bool CommuteChangesDestination(MachineInstr *MI, 464 unsigned &OpIdx) const; 465 virtual bool PredicateInstruction(MachineInstr *MI, 466 const SmallVectorImpl<MachineOperand> &Pred) const; 467 virtual void reMaterialize(MachineBasicBlock &MBB, 468 MachineBasicBlock::iterator MI, 469 unsigned DestReg, 470 const MachineInstr *Orig) const; 471 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const; 472}; 473 474} // End llvm namespace 475 476#endif 477