TargetInstrInfo.h revision ca1267c02b025cc719190b05f9e1a5d174a9caf7
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 LABEL = 2, 50 DECLARE = 3, 51 EXTRACT_SUBREG = 4, 52 INSERT_SUBREG = 5, 53 IMPLICIT_DEF = 6, 54 SUBREG_TO_REG = 7 55 }; 56 57 unsigned getNumOpcodes() const { return NumOpcodes; } 58 59 /// get - Return the machine instruction descriptor that corresponds to the 60 /// specified instruction opcode. 61 /// 62 const TargetInstrDesc &get(unsigned Opcode) const { 63 assert(Opcode < NumOpcodes && "Invalid opcode!"); 64 return Descriptors[Opcode]; 65 } 66 67 /// isTriviallyReMaterializable - Return true if the instruction is trivially 68 /// rematerializable, meaning it has no side effects and requires no operands 69 /// that aren't always available. 70 bool isTriviallyReMaterializable(MachineInstr *MI) const { 71 return MI->getDesc().isRematerializable() && 72 isReallyTriviallyReMaterializable(MI); 73 } 74 75protected: 76 /// isReallyTriviallyReMaterializable - For instructions with opcodes for 77 /// which the M_REMATERIALIZABLE flag is set, this function tests whether the 78 /// instruction itself is actually trivially rematerializable, considering 79 /// its operands. This is used for targets that have instructions that are 80 /// only trivially rematerializable for specific uses. This predicate must 81 /// return false if the instruction has any side effects other than 82 /// producing a value, or if it requres any address registers that are not 83 /// always available. 84 virtual bool isReallyTriviallyReMaterializable(MachineInstr *MI) const { 85 return true; 86 } 87 88public: 89 /// Return true if the instruction is a register to register move 90 /// and leave the source and dest operands in the passed parameters. 91 virtual bool isMoveInstr(const MachineInstr& MI, 92 unsigned& sourceReg, 93 unsigned& destReg) const { 94 return false; 95 } 96 97 /// isLoadFromStackSlot - If the specified machine instruction is a direct 98 /// load from a stack slot, return the virtual or physical register number of 99 /// the destination along with the FrameIndex of the loaded stack slot. If 100 /// not, return 0. This predicate must return 0 if the instruction has 101 /// any side effects other than loading from the stack slot. 102 virtual unsigned isLoadFromStackSlot(MachineInstr *MI, int &FrameIndex) const{ 103 return 0; 104 } 105 106 /// isStoreToStackSlot - If the specified machine instruction is a direct 107 /// store to a stack slot, return the virtual or physical register number of 108 /// the source reg along with the FrameIndex of the loaded stack slot. If 109 /// not, return 0. This predicate must return 0 if the instruction has 110 /// any side effects other than storing to the stack slot. 111 virtual unsigned isStoreToStackSlot(MachineInstr *MI, int &FrameIndex) const { 112 return 0; 113 } 114 115 /// reMaterialize - Re-issue the specified 'original' instruction at the 116 /// specific location targeting a new destination register. 117 virtual void reMaterialize(MachineBasicBlock &MBB, 118 MachineBasicBlock::iterator MI, 119 unsigned DestReg, 120 const MachineInstr *Orig) const = 0; 121 122 /// isInvariantLoad - Return true if the specified instruction (which is 123 /// marked mayLoad) is loading from a location whose value is invariant across 124 /// the function. For example, loading a value from the constant pool or from 125 /// from the argument area of a function if it does not change. This should 126 /// only return true of *all* loads the instruction does are invariant (if it 127 /// does multiple loads). 128 virtual bool isInvariantLoad(MachineInstr *MI) const { 129 return false; 130 } 131 132 /// convertToThreeAddress - This method must be implemented by targets that 133 /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target 134 /// may be able to convert a two-address instruction into one or more true 135 /// three-address instructions on demand. This allows the X86 target (for 136 /// example) to convert ADD and SHL instructions into LEA instructions if they 137 /// would require register copies due to two-addressness. 138 /// 139 /// This method returns a null pointer if the transformation cannot be 140 /// performed, otherwise it returns the last new instruction. 141 /// 142 virtual MachineInstr * 143 convertToThreeAddress(MachineFunction::iterator &MFI, 144 MachineBasicBlock::iterator &MBBI, LiveVariables &LV) const { 145 return 0; 146 } 147 148 /// commuteInstruction - If a target has any instructions that are commutable, 149 /// but require converting to a different instruction or making non-trivial 150 /// changes to commute them, this method can overloaded to do this. The 151 /// default implementation of this method simply swaps the first two operands 152 /// of MI and returns it. 153 /// 154 /// If a target wants to make more aggressive changes, they can construct and 155 /// return a new machine instruction. If an instruction cannot commute, it 156 /// can also return null. 157 /// 158 virtual MachineInstr *commuteInstruction(MachineInstr *MI) const = 0; 159 160 /// CommuteChangesDestination - Return true if commuting the specified 161 /// instruction will also changes the destination operand. Also return the 162 /// current operand index of the would be new destination register by 163 /// reference. This can happen when the commutable instruction is also a 164 /// two-address instruction. 165 virtual bool CommuteChangesDestination(MachineInstr *MI, 166 unsigned &OpIdx) const = 0; 167 168 /// AnalyzeBranch - Analyze the branching code at the end of MBB, returning 169 /// true if it cannot be understood (e.g. it's a switch dispatch or isn't 170 /// implemented for a target). Upon success, this returns false and returns 171 /// with the following information in various cases: 172 /// 173 /// 1. If this block ends with no branches (it just falls through to its succ) 174 /// just return false, leaving TBB/FBB null. 175 /// 2. If this block ends with only an unconditional branch, it sets TBB to be 176 /// the destination block. 177 /// 3. If this block ends with an conditional branch and it falls through to 178 /// an successor block, it sets TBB to be the branch destination block and a 179 /// list of operands that evaluate the condition. These 180 /// operands can be passed to other TargetInstrInfo methods to create new 181 /// branches. 182 /// 4. If this block ends with an conditional branch and an unconditional 183 /// block, it returns the 'true' destination in TBB, the 'false' destination 184 /// in FBB, and a list of operands that evaluate the condition. These 185 /// operands can be passed to other TargetInstrInfo methods to create new 186 /// branches. 187 /// 188 /// Note that RemoveBranch and InsertBranch must be implemented to support 189 /// cases where this method returns success. 190 /// 191 virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, 192 MachineBasicBlock *&FBB, 193 std::vector<MachineOperand> &Cond) const { 194 return true; 195 } 196 197 /// RemoveBranch - Remove the branching code at the end of the specific MBB. 198 /// this is only invoked in cases where AnalyzeBranch returns success. It 199 /// returns the number of instructions that were removed. 200 virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const { 201 assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!"); 202 return 0; 203 } 204 205 /// InsertBranch - Insert a branch into the end of the specified 206 /// MachineBasicBlock. This operands to this method are the same as those 207 /// returned by AnalyzeBranch. This is invoked in cases where AnalyzeBranch 208 /// returns success and when an unconditional branch (TBB is non-null, FBB is 209 /// null, Cond is empty) needs to be inserted. It returns the number of 210 /// instructions inserted. 211 virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, 212 MachineBasicBlock *FBB, 213 const std::vector<MachineOperand> &Cond) const { 214 assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!"); 215 return 0; 216 } 217 218 /// copyRegToReg - Add a copy between a pair of registers 219 virtual void copyRegToReg(MachineBasicBlock &MBB, 220 MachineBasicBlock::iterator MI, 221 unsigned DestReg, unsigned SrcReg, 222 const TargetRegisterClass *DestRC, 223 const TargetRegisterClass *SrcRC) const { 224 assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!"); 225 } 226 227 virtual void storeRegToStackSlot(MachineBasicBlock &MBB, 228 MachineBasicBlock::iterator MI, 229 unsigned SrcReg, bool isKill, int FrameIndex, 230 const TargetRegisterClass *RC) const { 231 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!"); 232 } 233 234 virtual void storeRegToAddr(MachineFunction &MF, unsigned SrcReg, bool isKill, 235 SmallVectorImpl<MachineOperand> &Addr, 236 const TargetRegisterClass *RC, 237 SmallVectorImpl<MachineInstr*> &NewMIs) const { 238 assert(0 && "Target didn't implement TargetInstrInfo::storeRegToAddr!"); 239 } 240 241 virtual void loadRegFromStackSlot(MachineBasicBlock &MBB, 242 MachineBasicBlock::iterator MI, 243 unsigned DestReg, int FrameIndex, 244 const TargetRegisterClass *RC) const { 245 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!"); 246 } 247 248 virtual void loadRegFromAddr(MachineFunction &MF, unsigned DestReg, 249 SmallVectorImpl<MachineOperand> &Addr, 250 const TargetRegisterClass *RC, 251 SmallVectorImpl<MachineInstr*> &NewMIs) const { 252 assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromAddr!"); 253 } 254 255 /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee 256 /// saved registers and returns true if it isn't possible / profitable to do 257 /// so by issuing a series of store instructions via 258 /// storeRegToStackSlot(). Returns false otherwise. 259 virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, 260 MachineBasicBlock::iterator MI, 261 const std::vector<CalleeSavedInfo> &CSI) const { 262 return false; 263 } 264 265 /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee 266 /// saved registers and returns true if it isn't possible / profitable to do 267 /// so by issuing a series of load instructions via loadRegToStackSlot(). 268 /// Returns false otherwise. 269 virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 270 MachineBasicBlock::iterator MI, 271 const std::vector<CalleeSavedInfo> &CSI) const { 272 return false; 273 } 274 275 /// foldMemoryOperand - Attempt to fold a load or store of the specified stack 276 /// slot into the specified machine instruction for the specified operand(s). 277 /// If this is possible, a new instruction is returned with the specified 278 /// operand folded, otherwise NULL is returned. The client is responsible for 279 /// removing the old instruction and adding the new one in the instruction 280 /// stream. 281 virtual MachineInstr* foldMemoryOperand(MachineFunction &MF, 282 MachineInstr* MI, 283 SmallVectorImpl<unsigned> &Ops, 284 int FrameIndex) const { 285 return 0; 286 } 287 288 /// foldMemoryOperand - Same as the previous version except it allows folding 289 /// of any load and store from / to any address, not just from a specific 290 /// stack slot. 291 virtual MachineInstr* foldMemoryOperand(MachineFunction &MF, 292 MachineInstr* MI, 293 SmallVectorImpl<unsigned> &Ops, 294 MachineInstr* LoadMI) const { 295 return 0; 296 } 297 298 /// canFoldMemoryOperand - Returns true if the specified load / store is 299 /// folding is possible. 300 virtual 301 bool canFoldMemoryOperand(MachineInstr *MI, 302 SmallVectorImpl<unsigned> &Ops) const{ 303 return false; 304 } 305 306 /// unfoldMemoryOperand - Separate a single instruction which folded a load or 307 /// a store or a load and a store into two or more instruction. If this is 308 /// possible, returns true as well as the new instructions by reference. 309 virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI, 310 unsigned Reg, bool UnfoldLoad, bool UnfoldStore, 311 SmallVectorImpl<MachineInstr*> &NewMIs) const{ 312 return false; 313 } 314 315 virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N, 316 SmallVectorImpl<SDNode*> &NewNodes) const { 317 return false; 318 } 319 320 /// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new 321 /// instruction after load / store are unfolded from an instruction of the 322 /// specified opcode. It returns zero if the specified unfolding is not 323 /// possible. 324 virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc, 325 bool UnfoldLoad, bool UnfoldStore) const { 326 return 0; 327 } 328 329 /// BlockHasNoFallThrough - Return true if the specified block does not 330 /// fall-through into its successor block. This is primarily used when a 331 /// branch is unanalyzable. It is useful for things like unconditional 332 /// indirect branches (jump tables). 333 virtual bool BlockHasNoFallThrough(MachineBasicBlock &MBB) const { 334 return false; 335 } 336 337 /// ReverseBranchCondition - Reverses the branch condition of the specified 338 /// condition list, returning false on success and true if it cannot be 339 /// reversed. 340 virtual bool ReverseBranchCondition(std::vector<MachineOperand> &Cond) const { 341 return true; 342 } 343 344 /// insertNoop - Insert a noop into the instruction stream at the specified 345 /// point. 346 virtual void insertNoop(MachineBasicBlock &MBB, 347 MachineBasicBlock::iterator MI) const { 348 assert(0 && "Target didn't implement insertNoop!"); 349 abort(); 350 } 351 352 /// isPredicated - Returns true if the instruction is already predicated. 353 /// 354 virtual bool isPredicated(const MachineInstr *MI) const { 355 return false; 356 } 357 358 /// isUnpredicatedTerminator - Returns true if the instruction is a 359 /// terminator instruction that has not been predicated. 360 virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const; 361 362 /// PredicateInstruction - Convert the instruction into a predicated 363 /// instruction. It returns true if the operation was successful. 364 virtual 365 bool PredicateInstruction(MachineInstr *MI, 366 const std::vector<MachineOperand> &Pred) const = 0; 367 368 /// SubsumesPredicate - Returns true if the first specified predicate 369 /// subsumes the second, e.g. GE subsumes GT. 370 virtual 371 bool SubsumesPredicate(const std::vector<MachineOperand> &Pred1, 372 const std::vector<MachineOperand> &Pred2) const { 373 return false; 374 } 375 376 /// DefinesPredicate - If the specified instruction defines any predicate 377 /// or condition code register(s) used for predication, returns true as well 378 /// as the definition predicate(s) by reference. 379 virtual bool DefinesPredicate(MachineInstr *MI, 380 std::vector<MachineOperand> &Pred) const { 381 return false; 382 } 383 384 /// getPointerRegClass - Returns a TargetRegisterClass used for pointer 385 /// values. 386 virtual const TargetRegisterClass *getPointerRegClass() const { 387 assert(0 && "Target didn't implement getPointerRegClass!"); 388 abort(); 389 return 0; // Must return a value in order to compile with VS 2005 390 } 391}; 392 393/// TargetInstrInfoImpl - This is the default implementation of 394/// TargetInstrInfo, which just provides a couple of default implementations 395/// for various methods. This separated out because it is implemented in 396/// libcodegen, not in libtarget. 397class TargetInstrInfoImpl : public TargetInstrInfo { 398protected: 399 TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes) 400 : TargetInstrInfo(desc, NumOpcodes) {} 401public: 402 virtual MachineInstr *commuteInstruction(MachineInstr *MI) const; 403 virtual bool CommuteChangesDestination(MachineInstr *MI, 404 unsigned &OpIdx) const; 405 virtual bool PredicateInstruction(MachineInstr *MI, 406 const std::vector<MachineOperand> &Pred) const; 407 virtual void reMaterialize(MachineBasicBlock &MBB, 408 MachineBasicBlock::iterator MI, 409 unsigned DestReg, 410 const MachineInstr *Orig) const; 411}; 412 413} // End llvm namespace 414 415#endif 416