TargetInstrInfo.h revision af76e592c7f9deff0e55c13dbb4a34f07f1c7f64
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 MCAsmInfo; 23class TargetRegisterClass; 24class TargetRegisterInfo; 25class LiveVariables; 26class CalleeSavedInfo; 27class SDNode; 28class SelectionDAG; 29 30template<class T> class SmallVectorImpl; 31 32 33//--------------------------------------------------------------------------- 34/// 35/// TargetInstrInfo - Interface to description of machine instruction set 36/// 37class TargetInstrInfo { 38 const TargetInstrDesc *Descriptors; // Raw array to allow static init'n 39 unsigned NumOpcodes; // Number of entries in the desc array 40 41 TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT 42 void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT 43public: 44 TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes); 45 virtual ~TargetInstrInfo(); 46 47 // Invariant opcodes: All instruction sets have these as their low opcodes. 48 enum { 49 PHI = 0, 50 INLINEASM = 1, 51 DBG_LABEL = 2, 52 EH_LABEL = 3, 53 GC_LABEL = 4, 54 // FIXME: DECLARE is removed. Readjust enum values ? 55 56 /// EXTRACT_SUBREG - This instruction takes two operands: a register 57 /// that has subregisters, and a subregister index. It returns the 58 /// extracted subregister value. This is commonly used to implement 59 /// truncation operations on target architectures which support it. 60 EXTRACT_SUBREG = 6, 61 62 /// INSERT_SUBREG - This instruction takes three operands: a register 63 /// that has subregisters, a register providing an insert value, and a 64 /// subregister index. It returns the value of the first register with 65 /// the value of the second register inserted. The first register is 66 /// often defined by an IMPLICIT_DEF, as is commonly used to implement 67 /// anyext operations on target architectures which support it. 68 INSERT_SUBREG = 7, 69 70 /// IMPLICIT_DEF - This is the MachineInstr-level equivalent of undef. 71 IMPLICIT_DEF = 8, 72 73 /// SUBREG_TO_REG - This instruction is similar to INSERT_SUBREG except 74 /// that the first operand is an immediate integer constant. This constant 75 /// is often zero, as is commonly used to implement zext operations on 76 /// target architectures which support it, such as with x86-64 (with 77 /// zext from i32 to i64 via implicit zero-extension). 78 SUBREG_TO_REG = 9, 79 80 /// COPY_TO_REGCLASS - This instruction is a placeholder for a plain 81 /// register-to-register copy into a specific register class. This is only 82 /// used between instruction selection and MachineInstr creation, before 83 /// virtual registers have been created for all the instructions, and it's 84 /// only needed in cases where the register classes implied by the 85 /// instructions are insufficient. The actual MachineInstrs to perform 86 /// the copy are emitted with the TargetInstrInfo::copyRegToReg hook. 87 COPY_TO_REGCLASS = 10 88 }; 89 90 unsigned getNumOpcodes() const { return NumOpcodes; } 91 92 /// get - Return the machine instruction descriptor that corresponds to the 93 /// specified instruction opcode. 94 /// 95 const TargetInstrDesc &get(unsigned Opcode) const { 96 assert(Opcode < NumOpcodes && "Invalid opcode!"); 97 return Descriptors[Opcode]; 98 } 99 100 /// isTriviallyReMaterializable - Return true if the instruction is trivially 101 /// rematerializable, meaning it has no side effects and requires no operands 102 /// that aren't always available. 103 bool isTriviallyReMaterializable(const MachineInstr *MI) const { 104 return MI->getDesc().isRematerializable() && 105 isReallyTriviallyReMaterializable(MI); 106 } 107 108protected: 109 /// isReallyTriviallyReMaterializable - For instructions with opcodes for 110 /// which the M_REMATERIALIZABLE flag is set, this function tests whether the 111 /// instruction itself is actually trivially rematerializable, considering 112 /// its operands. This is used for targets that have instructions that are 113 /// only trivially rematerializable for specific uses. This predicate must 114 /// return false if the instruction has any side effects other than 115 /// producing a value, or if it requres any address registers that are not 116 /// always available. 117 virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI) const { 118 return true; 119 } 120 121public: 122 /// Return true if the instruction is a register to register move and return 123 /// the source and dest operands and their sub-register indices by reference. 124 virtual bool isMoveInstr(const MachineInstr& MI, 125 unsigned& SrcReg, unsigned& DstReg, 126 unsigned& SrcSubIdx, unsigned& DstSubIdx) const { 127 return false; 128 } 129 130 /// isLoadFromStackSlot - If the specified machine instruction is a direct 131 /// load from a stack slot, return the virtual or physical register number of 132 /// the destination along with the FrameIndex of the loaded stack slot. If 133 /// not, return 0. This predicate must return 0 if the instruction has 134 /// any side effects other than loading from the stack slot. 135 virtual unsigned isLoadFromStackSlot(const MachineInstr *MI, 136 int &FrameIndex) const { 137 return 0; 138 } 139 140 /// isStoreToStackSlot - If the specified machine instruction is a direct 141 /// store to a stack slot, return the virtual or physical register number of 142 /// the source reg along with the FrameIndex of the loaded stack slot. If 143 /// not, return 0. This predicate must return 0 if the instruction has 144 /// any side effects other than storing to the stack slot. 145 virtual unsigned isStoreToStackSlot(const MachineInstr *MI, 146 int &FrameIndex) const { 147 return 0; 148 } 149 150 /// reMaterialize - Re-issue the specified 'original' instruction at the 151 /// specific location targeting a new destination register. 152 virtual void reMaterialize(MachineBasicBlock &MBB, 153 MachineBasicBlock::iterator MI, 154 unsigned DestReg, unsigned SubIdx, 155 const MachineInstr *Orig) const = 0; 156 157 /// isInvariantLoad - Return true if the specified instruction (which is 158 /// marked mayLoad) is loading from a location whose value is invariant across 159 /// the function. For example, loading a value from the constant pool or from 160 /// from the argument area of a function if it does not change. This should 161 /// only return true of *all* loads the instruction does are invariant (if it 162 /// does multiple loads). 163 virtual bool isInvariantLoad(const MachineInstr *MI) const { 164 return false; 165 } 166 167 /// convertToThreeAddress - This method must be implemented by targets that 168 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target 169 /// may be able to convert a two-address instruction into one or more true 170 /// three-address instructions on demand. This allows the X86 target (for 171 /// example) to convert ADD and SHL instructions into LEA instructions if they 172 /// would require register copies due to two-addressness. 173 /// 174 /// This method returns a null pointer if the transformation cannot be 175 /// performed, otherwise it returns the last new instruction. 176 /// 177 virtual MachineInstr * 178 convertToThreeAddress(MachineFunction::iterator &MFI, 179 MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const { 180 return 0; 181 } 182 183 /// commuteInstruction - If a target has any instructions that are commutable, 184 /// but require converting to a different instruction or making non-trivial 185 /// changes to commute them, this method can overloaded to do this. The 186 /// default implementation of this method simply swaps the first two operands 187 /// of MI and returns it. 188 /// 189 /// If a target wants to make more aggressive changes, they can construct and 190 /// return a new machine instruction. If an instruction cannot commute, it 191 /// can also return null. 192 /// 193 /// If NewMI is true, then a new machine instruction must be created. 194 /// 195 virtual MachineInstr *commuteInstruction(MachineInstr *MI, 196 bool NewMI = false) const = 0; 197 198 /// findCommutedOpIndices - If specified MI is commutable, return the two 199 /// operand indices that would swap value. Return true if the instruction 200 /// is not in a form which this routine understands. 201 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1, 202 unsigned &SrcOpIdx2) const = 0; 203 204 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning 205 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't 206 /// implemented for a target). Upon success, this returns false and returns 207 /// with the following information in various cases: 208 /// 209 /// 1. If this block ends with no branches (it just falls through to its succ) 210 /// just return false, leaving TBB/FBB null. 211 /// 2. If this block ends with only an unconditional branch, it sets TBB to be 212 /// the destination block. 213 /// 3. If this block ends with an conditional branch and it falls through to 214 /// a successor block, it sets TBB to be the branch destination block and 215 /// a list of operands that evaluate the condition. These 216 /// operands can be passed to other TargetInstrInfo methods to create new 217 /// branches. 218 /// 4. If this block ends with a conditional branch followed by an 219 /// unconditional branch, it returns the 'true' destination in TBB, the 220 /// 'false' destination in FBB, and a list of operands that evaluate the 221 /// condition. These operands can be passed to other TargetInstrInfo 222 /// methods to create new branches. 223 /// 224 /// Note that RemoveBranch and InsertBranch must be implemented to support 225 /// cases where this method returns success. 226 /// 227 /// If AllowModify is true, then this routine is allowed to modify the basic 228 /// block (e.g. delete instructions after the unconditional branch). 229 /// 230 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, 231 MachineBasicBlock *&FBB, 232 SmallVectorImpl<MachineOperand> &Cond, 233 bool AllowModify = false) const { 234 return true; 235 } 236 237 /// RemoveBranch - Remove the branching code at the end of the specific MBB. 238 /// This is only invoked in cases where AnalyzeBranch returns success. It 239 /// returns the number of instructions that were removed. 240 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const { 241 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!"); 242 return 0; 243 } 244 245 /// InsertBranch - Insert branch code into the end of the specified 246 /// MachineBasicBlock. The operands to this method are the same as those 247 /// returned by AnalyzeBranch. This is only invoked in cases where 248 /// AnalyzeBranch returns success. It returns the number of instructions 249 /// inserted. 250 /// 251 /// It is also invoked by tail merging to add unconditional branches in 252 /// cases where AnalyzeBranch doesn't apply because there was no original 253 /// branch to analyze. At least this much must be implemented, else tail 254 /// merging needs to be disabled. 255 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, 256 MachineBasicBlock *FBB, 257 const SmallVectorImpl<MachineOperand> &Cond) const { 258 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!"); 259 return 0; 260 } 261 262 /// copyRegToReg - Emit instructions to copy between a pair of registers. It 263 /// returns false if the target does not how to copy between the specified 264 /// registers. 265 virtual bool copyRegToReg(MachineBasicBlock &MBB, 266 MachineBasicBlock::iterator MI, 267 unsigned DestReg, unsigned SrcReg, 268 const TargetRegisterClass *DestRC, 269 const TargetRegisterClass *SrcRC) const { 270 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!"); 271 return false; 272 } 273 274 /// storeRegToStackSlot - Store the specified register of the given register 275 /// class to the specified stack frame index. The store instruction is to be 276 /// added to the given machine basic block before the specified machine 277 /// instruction. If isKill is true, the register operand is the last use and 278 /// must be marked kill. 279 virtual void storeRegToStackSlot(MachineBasicBlock &MBB, 280 MachineBasicBlock::iterator MI, 281 unsigned SrcReg, bool isKill, int FrameIndex, 282 const TargetRegisterClass *RC) const { 283 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!"); 284 } 285 286 /// loadRegFromStackSlot - Load the specified register of the given register 287 /// class from the specified stack frame index. The load instruction is to be 288 /// added to the given machine basic block before the specified machine 289 /// instruction. 290 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB, 291 MachineBasicBlock::iterator MI, 292 unsigned DestReg, int FrameIndex, 293 const TargetRegisterClass *RC) const { 294 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!"); 295 } 296 297 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee 298 /// saved registers and returns true if it isn't possible / profitable to do 299 /// so by issuing a series of store instructions via 300 /// storeRegToStackSlot(). Returns false otherwise. 301 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, 302 MachineBasicBlock::iterator MI, 303 const std::vector<CalleeSavedInfo> &CSI) const { 304 return false; 305 } 306 307 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee 308 /// saved registers and returns true if it isn't possible / profitable to do 309 /// so by issuing a series of load instructions via loadRegToStackSlot(). 310 /// Returns false otherwise. 311 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 312 MachineBasicBlock::iterator MI, 313 const std::vector<CalleeSavedInfo> &CSI) const { 314 return false; 315 } 316 317 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack 318 /// slot into the specified machine instruction for the specified operand(s). 319 /// If this is possible, a new instruction is returned with the specified 320 /// operand folded, otherwise NULL is returned. The client is responsible for 321 /// removing the old instruction and adding the new one in the instruction 322 /// stream. 323 MachineInstr* foldMemoryOperand(MachineFunction &MF, 324 MachineInstr* MI, 325 const SmallVectorImpl<unsigned> &Ops, 326 int FrameIndex) const; 327 328 /// foldMemoryOperand - Same as the previous version except it allows folding 329 /// of any load and store from / to any address, not just from a specific 330 /// stack slot. 331 MachineInstr* foldMemoryOperand(MachineFunction &MF, 332 MachineInstr* MI, 333 const SmallVectorImpl<unsigned> &Ops, 334 MachineInstr* LoadMI) const; 335 336protected: 337 /// foldMemoryOperandImpl - Target-dependent implementation for 338 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will 339 /// take care of adding a MachineMemOperand to the newly created instruction. 340 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF, 341 MachineInstr* MI, 342 const SmallVectorImpl<unsigned> &Ops, 343 int FrameIndex) const { 344 return 0; 345 } 346 347 /// foldMemoryOperandImpl - Target-dependent implementation for 348 /// foldMemoryOperand. Target-independent code in foldMemoryOperand will 349 /// take care of adding a MachineMemOperand to the newly created instruction. 350 virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF, 351 MachineInstr* MI, 352 const SmallVectorImpl<unsigned> &Ops, 353 MachineInstr* LoadMI) const { 354 return 0; 355 } 356 357public: 358 /// canFoldMemoryOperand - Returns true for the specified load / store if 359 /// folding is possible. 360 virtual 361 bool canFoldMemoryOperand(const MachineInstr *MI, 362 const SmallVectorImpl<unsigned> &Ops) const { 363 return false; 364 } 365 366 /// unfoldMemoryOperand - Separate a single instruction which folded a load or 367 /// a store or a load and a store into two or more instruction. If this is 368 /// possible, returns true as well as the new instructions by reference. 369 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI, 370 unsigned Reg, bool UnfoldLoad, bool UnfoldStore, 371 SmallVectorImpl<MachineInstr*> &NewMIs) const{ 372 return false; 373 } 374 375 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N, 376 SmallVectorImpl<SDNode*> &NewNodes) const { 377 return false; 378 } 379 380 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new 381 /// instruction after load / store are unfolded from an instruction of the 382 /// specified opcode. It returns zero if the specified unfolding is not 383 /// possible. 384 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc, 385 bool UnfoldLoad, bool UnfoldStore) const { 386 return 0; 387 } 388 389 /// BlockHasNoFallThrough - Return true if the specified block does not 390 /// fall-through into its successor block. This is primarily used when a 391 /// branch is unanalyzable. It is useful for things like unconditional 392 /// indirect branches (jump tables). 393 virtual bool BlockHasNoFallThrough(const MachineBasicBlock &MBB) const { 394 return false; 395 } 396 397 /// ReverseBranchCondition - Reverses the branch condition of the specified 398 /// condition list, returning false on success and true if it cannot be 399 /// reversed. 400 virtual 401 bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const { 402 return true; 403 } 404 405 /// insertNoop - Insert a noop into the instruction stream at the specified 406 /// point. 407 virtual void insertNoop(MachineBasicBlock &MBB, 408 MachineBasicBlock::iterator MI) const; 409 410 /// isPredicated - Returns true if the instruction is already predicated. 411 /// 412 virtual bool isPredicated(const MachineInstr *MI) const { 413 return false; 414 } 415 416 /// isUnpredicatedTerminator - Returns true if the instruction is a 417 /// terminator instruction that has not been predicated. 418 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const; 419 420 /// PredicateInstruction - Convert the instruction into a predicated 421 /// instruction. It returns true if the operation was successful. 422 virtual 423 bool PredicateInstruction(MachineInstr *MI, 424 const SmallVectorImpl<MachineOperand> &Pred) const = 0; 425 426 /// SubsumesPredicate - Returns true if the first specified predicate 427 /// subsumes the second, e.g. GE subsumes GT. 428 virtual 429 bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1, 430 const SmallVectorImpl<MachineOperand> &Pred2) const { 431 return false; 432 } 433 434 /// DefinesPredicate - If the specified instruction defines any predicate 435 /// or condition code register(s) used for predication, returns true as well 436 /// as the definition predicate(s) by reference. 437 virtual bool DefinesPredicate(MachineInstr *MI, 438 std::vector<MachineOperand> &Pred) const { 439 return false; 440 } 441 442 /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine 443 /// instruction that defines the specified register class. 444 virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const { 445 return true; 446 } 447 448 /// isDeadInstruction - Return true if the instruction is considered dead. 449 /// This allows some late codegen passes to delete them. 450 virtual bool isDeadInstruction(const MachineInstr *MI) const = 0; 451 452 /// GetInstSize - Returns the size of the specified Instruction. 453 /// 454 virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const { 455 assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!"); 456 return 0; 457 } 458 459 /// GetFunctionSizeInBytes - Returns the size of the specified 460 /// MachineFunction. 461 /// 462 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0; 463 464 /// Measure the specified inline asm to determine an approximation of its 465 /// length. 466 virtual unsigned getInlineAsmLength(const char *Str, 467 const MCAsmInfo &TAI) const; 468}; 469 470/// TargetInstrInfoImpl - This is the default implementation of 471/// TargetInstrInfo, which just provides a couple of default implementations 472/// for various methods. This separated out because it is implemented in 473/// libcodegen, not in libtarget. 474class TargetInstrInfoImpl : public TargetInstrInfo { 475protected: 476 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes) 477 : TargetInstrInfo(desc, NumOpcodes) {} 478public: 479 virtual MachineInstr *commuteInstruction(MachineInstr *MI, 480 bool NewMI = false) const; 481 virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1, 482 unsigned &SrcOpIdx2) const; 483 virtual bool PredicateInstruction(MachineInstr *MI, 484 const SmallVectorImpl<MachineOperand> &Pred) const; 485 virtual void reMaterialize(MachineBasicBlock &MBB, 486 MachineBasicBlock::iterator MI, 487 unsigned DestReg, unsigned SubReg, 488 const MachineInstr *Orig) const; 489 virtual bool isDeadInstruction(const MachineInstr *MI) const; 490 491 virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const; 492}; 493 494} // End llvm namespace 495 496#endif 497