1 //===- Local.h - Functions to perform local transformations -----*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This family of functions perform various local transformations to the 10 // program. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H 15 #define LLVM_TRANSFORMS_UTILS_LOCAL_H 16 17 #include "llvm/ADT/ArrayRef.h" 18 #include "llvm/IR/Dominators.h" 19 #include "llvm/Support/CommandLine.h" 20 #include "llvm/Transforms/Utils/SimplifyCFGOptions.h" 21 #include "llvm/Transforms/Utils/ValueMapper.h" 22 #include <cstdint> 23 24 namespace llvm { 25 26 class DataLayout; 27 class Value; 28 class WeakTrackingVH; 29 class WeakVH; 30 template <typename T> class SmallVectorImpl; 31 class AAResults; 32 class AllocaInst; 33 class AssumptionCache; 34 class BasicBlock; 35 class BranchInst; 36 class CallBase; 37 class CallInst; 38 class DbgVariableIntrinsic; 39 class DIBuilder; 40 class DomTreeUpdater; 41 class Function; 42 class Instruction; 43 class InvokeInst; 44 class LoadInst; 45 class MDNode; 46 class MemorySSAUpdater; 47 class PHINode; 48 class StoreInst; 49 class TargetLibraryInfo; 50 class TargetTransformInfo; 51 52 //===----------------------------------------------------------------------===// 53 // Local constant propagation. 54 // 55 56 /// If a terminator instruction is predicated on a constant value, convert it 57 /// into an unconditional branch to the constant destination. 58 /// This is a nontrivial operation because the successors of this basic block 59 /// must have their PHI nodes updated. 60 /// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch 61 /// conditions and indirectbr addresses this might make dead if 62 /// DeleteDeadConditions is true. 63 bool ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions = false, 64 const TargetLibraryInfo *TLI = nullptr, 65 DomTreeUpdater *DTU = nullptr); 66 67 //===----------------------------------------------------------------------===// 68 // Local dead code elimination. 69 // 70 71 /// Return true if the result produced by the instruction is not used, and the 72 /// instruction will return. Certain side-effecting instructions are also 73 /// considered dead if there are no uses of the instruction. 74 bool isInstructionTriviallyDead(Instruction *I, 75 const TargetLibraryInfo *TLI = nullptr); 76 77 /// Return true if the result produced by the instruction would have no side 78 /// effects if it was not used. This is equivalent to checking whether 79 /// isInstructionTriviallyDead would be true if the use count was 0. 80 bool wouldInstructionBeTriviallyDead(const Instruction *I, 81 const TargetLibraryInfo *TLI = nullptr); 82 83 /// Return true if the result produced by the instruction has no side effects on 84 /// any paths other than where it is used. This is less conservative than 85 /// wouldInstructionBeTriviallyDead which is based on the assumption 86 /// that the use count will be 0. An example usage of this API is for 87 /// identifying instructions that can be sunk down to use(s). 88 bool wouldInstructionBeTriviallyDeadOnUnusedPaths( 89 Instruction *I, const TargetLibraryInfo *TLI = nullptr); 90 91 /// If the specified value is a trivially dead instruction, delete it. 92 /// If that makes any of its operands trivially dead, delete them too, 93 /// recursively. Return true if any instructions were deleted. 94 bool RecursivelyDeleteTriviallyDeadInstructions( 95 Value *V, const TargetLibraryInfo *TLI = nullptr, 96 MemorySSAUpdater *MSSAU = nullptr, 97 std::function<void(Value *)> AboutToDeleteCallback = 98 std::function<void(Value *)>()); 99 100 /// Delete all of the instructions in `DeadInsts`, and all other instructions 101 /// that deleting these in turn causes to be trivially dead. 102 /// 103 /// The initial instructions in the provided vector must all have empty use 104 /// lists and satisfy `isInstructionTriviallyDead`. 105 /// 106 /// `DeadInsts` will be used as scratch storage for this routine and will be 107 /// empty afterward. 108 void RecursivelyDeleteTriviallyDeadInstructions( 109 SmallVectorImpl<WeakTrackingVH> &DeadInsts, 110 const TargetLibraryInfo *TLI = nullptr, MemorySSAUpdater *MSSAU = nullptr, 111 std::function<void(Value *)> AboutToDeleteCallback = 112 std::function<void(Value *)>()); 113 114 /// Same functionality as RecursivelyDeleteTriviallyDeadInstructions, but allow 115 /// instructions that are not trivially dead. These will be ignored. 116 /// Returns true if any changes were made, i.e. any instructions trivially dead 117 /// were found and deleted. 118 bool RecursivelyDeleteTriviallyDeadInstructionsPermissive( 119 SmallVectorImpl<WeakTrackingVH> &DeadInsts, 120 const TargetLibraryInfo *TLI = nullptr, MemorySSAUpdater *MSSAU = nullptr, 121 std::function<void(Value *)> AboutToDeleteCallback = 122 std::function<void(Value *)>()); 123 124 /// If the specified value is an effectively dead PHI node, due to being a 125 /// def-use chain of single-use nodes that either forms a cycle or is terminated 126 /// by a trivially dead instruction, delete it. If that makes any of its 127 /// operands trivially dead, delete them too, recursively. Return true if a 128 /// change was made. 129 bool RecursivelyDeleteDeadPHINode(PHINode *PN, 130 const TargetLibraryInfo *TLI = nullptr, 131 MemorySSAUpdater *MSSAU = nullptr); 132 133 /// Scan the specified basic block and try to simplify any instructions in it 134 /// and recursively delete dead instructions. 135 /// 136 /// This returns true if it changed the code, note that it can delete 137 /// instructions in other blocks as well in this block. 138 bool SimplifyInstructionsInBlock(BasicBlock *BB, 139 const TargetLibraryInfo *TLI = nullptr); 140 141 /// Replace all the uses of an SSA value in @llvm.dbg intrinsics with 142 /// undef. This is useful for signaling that a variable, e.g. has been 143 /// found dead and hence it's unavailable at a given program point. 144 /// Returns true if the dbg values have been changed. 145 bool replaceDbgUsesWithUndef(Instruction *I); 146 147 //===----------------------------------------------------------------------===// 148 // Control Flow Graph Restructuring. 149 // 150 151 /// BB is a block with one predecessor and its predecessor is known to have one 152 /// successor (BB!). Eliminate the edge between them, moving the instructions in 153 /// the predecessor into BB. This deletes the predecessor block. 154 void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, DomTreeUpdater *DTU = nullptr); 155 156 /// BB is known to contain an unconditional branch, and contains no instructions 157 /// other than PHI nodes, potential debug intrinsics and the branch. If 158 /// possible, eliminate BB by rewriting all the predecessors to branch to the 159 /// successor block and return true. If we can't transform, return false. 160 bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB, 161 DomTreeUpdater *DTU = nullptr); 162 163 /// Check for and eliminate duplicate PHI nodes in this block. This doesn't try 164 /// to be clever about PHI nodes which differ only in the order of the incoming 165 /// values, but instcombine orders them so it usually won't matter. 166 /// 167 /// This overload removes the duplicate PHI nodes directly. 168 bool EliminateDuplicatePHINodes(BasicBlock *BB); 169 170 /// Check for and eliminate duplicate PHI nodes in this block. This doesn't try 171 /// to be clever about PHI nodes which differ only in the order of the incoming 172 /// values, but instcombine orders them so it usually won't matter. 173 /// 174 /// This overload collects the PHI nodes to be removed into the ToRemove set. 175 bool EliminateDuplicatePHINodes(BasicBlock *BB, 176 SmallPtrSetImpl<PHINode *> &ToRemove); 177 178 /// This function is used to do simplification of a CFG. For example, it 179 /// adjusts branches to branches to eliminate the extra hop, it eliminates 180 /// unreachable basic blocks, and does other peephole optimization of the CFG. 181 /// It returns true if a modification was made, possibly deleting the basic 182 /// block that was pointed to. LoopHeaders is an optional input parameter 183 /// providing the set of loop headers that SimplifyCFG should not eliminate. 184 extern cl::opt<bool> RequireAndPreserveDomTree; 185 bool simplifyCFG(BasicBlock *BB, const TargetTransformInfo &TTI, 186 DomTreeUpdater *DTU = nullptr, 187 const SimplifyCFGOptions &Options = {}, 188 ArrayRef<WeakVH> LoopHeaders = {}); 189 190 /// This function is used to flatten a CFG. For example, it uses parallel-and 191 /// and parallel-or mode to collapse if-conditions and merge if-regions with 192 /// identical statements. 193 bool FlattenCFG(BasicBlock *BB, AAResults *AA = nullptr); 194 195 /// If this basic block is ONLY a setcc and a branch, and if a predecessor 196 /// branches to us and one of our successors, fold the setcc into the 197 /// predecessor and use logical operations to pick the right destination. 198 bool FoldBranchToCommonDest(BranchInst *BI, llvm::DomTreeUpdater *DTU = nullptr, 199 MemorySSAUpdater *MSSAU = nullptr, 200 const TargetTransformInfo *TTI = nullptr, 201 unsigned BonusInstThreshold = 1); 202 203 /// This function takes a virtual register computed by an Instruction and 204 /// replaces it with a slot in the stack frame, allocated via alloca. 205 /// This allows the CFG to be changed around without fear of invalidating the 206 /// SSA information for the value. It returns the pointer to the alloca inserted 207 /// to create a stack slot for X. 208 AllocaInst *DemoteRegToStack(Instruction &X, 209 bool VolatileLoads = false, 210 std::optional<BasicBlock::iterator> AllocaPoint = std::nullopt); 211 212 /// This function takes a virtual register computed by a phi node and replaces 213 /// it with a slot in the stack frame, allocated via alloca. The phi node is 214 /// deleted and it returns the pointer to the alloca inserted. 215 AllocaInst *DemotePHIToStack(PHINode *P, std::optional<BasicBlock::iterator> AllocaPoint = std::nullopt); 216 217 /// If the specified pointer points to an object that we control, try to modify 218 /// the object's alignment to PrefAlign. Returns a minimum known alignment of 219 /// the value after the operation, which may be lower than PrefAlign. 220 /// 221 /// Increating value alignment isn't often possible though. If alignment is 222 /// important, a more reliable approach is to simply align all global variables 223 /// and allocation instructions to their preferred alignment from the beginning. 224 Align tryEnforceAlignment(Value *V, Align PrefAlign, const DataLayout &DL); 225 226 /// Try to ensure that the alignment of \p V is at least \p PrefAlign bytes. If 227 /// the owning object can be modified and has an alignment less than \p 228 /// PrefAlign, it will be increased and \p PrefAlign returned. If the alignment 229 /// cannot be increased, the known alignment of the value is returned. 230 /// 231 /// It is not always possible to modify the alignment of the underlying object, 232 /// so if alignment is important, a more reliable approach is to simply align 233 /// all global variables and allocation instructions to their preferred 234 /// alignment from the beginning. 235 Align getOrEnforceKnownAlignment(Value *V, MaybeAlign PrefAlign, 236 const DataLayout &DL, 237 const Instruction *CxtI = nullptr, 238 AssumptionCache *AC = nullptr, 239 const DominatorTree *DT = nullptr); 240 241 /// Try to infer an alignment for the specified pointer. 242 inline Align getKnownAlignment(Value *V, const DataLayout &DL, 243 const Instruction *CxtI = nullptr, 244 AssumptionCache *AC = nullptr, 245 const DominatorTree *DT = nullptr) { 246 return getOrEnforceKnownAlignment(V, MaybeAlign(), DL, CxtI, AC, DT); 247 } 248 249 /// Create a call that matches the invoke \p II in terms of arguments, 250 /// attributes, debug information, etc. The call is not placed in a block and it 251 /// will not have a name. The invoke instruction is not removed, nor are the 252 /// uses replaced by the new call. 253 CallInst *createCallMatchingInvoke(InvokeInst *II); 254 255 /// This function converts the specified invoke into a normal call. 256 CallInst *changeToCall(InvokeInst *II, DomTreeUpdater *DTU = nullptr); 257 258 ///===---------------------------------------------------------------------===// 259 /// Dbg Intrinsic utilities 260 /// 261 262 /// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value 263 /// that has an associated llvm.dbg.declare intrinsic. 264 void ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII, 265 StoreInst *SI, DIBuilder &Builder); 266 void ConvertDebugDeclareToDebugValue(DbgVariableRecord *DVR, StoreInst *SI, 267 DIBuilder &Builder); 268 269 /// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value 270 /// that has an associated llvm.dbg.declare intrinsic. 271 void ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII, 272 LoadInst *LI, DIBuilder &Builder); 273 void ConvertDebugDeclareToDebugValue(DbgVariableRecord *DVR, LoadInst *LI, 274 DIBuilder &Builder); 275 276 /// Inserts a llvm.dbg.value intrinsic after a phi that has an associated 277 /// llvm.dbg.declare intrinsic. 278 void ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII, 279 PHINode *LI, DIBuilder &Builder); 280 void ConvertDebugDeclareToDebugValue(DbgVariableRecord *DVR, PHINode *LI, 281 DIBuilder &Builder); 282 283 /// Lowers llvm.dbg.declare intrinsics into appropriate set of 284 /// llvm.dbg.value intrinsics. 285 bool LowerDbgDeclare(Function &F); 286 287 /// Propagate dbg.value intrinsics through the newly inserted PHIs. 288 void insertDebugValuesForPHIs(BasicBlock *BB, 289 SmallVectorImpl<PHINode *> &InsertedPHIs); 290 291 /// Replaces llvm.dbg.declare instruction when the address it 292 /// describes is replaced with a new value. If Deref is true, an 293 /// additional DW_OP_deref is prepended to the expression. If Offset 294 /// is non-zero, a constant displacement is added to the expression 295 /// (between the optional Deref operations). Offset can be negative. 296 bool replaceDbgDeclare(Value *Address, Value *NewAddress, DIBuilder &Builder, 297 uint8_t DIExprFlags, int Offset); 298 299 /// Replaces multiple llvm.dbg.value instructions when the alloca it describes 300 /// is replaced with a new value. If Offset is non-zero, a constant displacement 301 /// is added to the expression (after the mandatory Deref). Offset can be 302 /// negative. New llvm.dbg.value instructions are inserted at the locations of 303 /// the instructions they replace. 304 void replaceDbgValueForAlloca(AllocaInst *AI, Value *NewAllocaAddress, 305 DIBuilder &Builder, int Offset = 0); 306 307 /// Assuming the instruction \p I is going to be deleted, attempt to salvage 308 /// debug users of \p I by writing the effect of \p I in a DIExpression. If it 309 /// cannot be salvaged changes its debug uses to undef. 310 void salvageDebugInfo(Instruction &I); 311 312 /// Implementation of salvageDebugInfo, applying only to instructions in 313 /// \p Insns, rather than all debug users from findDbgUsers( \p I). 314 /// Mark undef if salvaging cannot be completed. 315 void salvageDebugInfoForDbgValues(Instruction &I, 316 ArrayRef<DbgVariableIntrinsic *> Insns, 317 ArrayRef<DbgVariableRecord *> DPInsns); 318 319 /// Given an instruction \p I and DIExpression \p DIExpr operating on 320 /// it, append the effects of \p I to the DIExpression operand list 321 /// \p Ops, or return \p nullptr if it cannot be salvaged. 322 /// \p CurrentLocOps is the number of SSA values referenced by the 323 /// incoming \p Ops. \return the first non-constant operand 324 /// implicitly referred to by Ops. If \p I references more than one 325 /// non-constant operand, any additional operands are added to 326 /// \p AdditionalValues. 327 /// 328 /// \example 329 //// 330 /// I = add %a, i32 1 331 /// 332 /// Return = %a 333 /// Ops = llvm::dwarf::DW_OP_lit1 llvm::dwarf::DW_OP_add 334 /// 335 /// I = add %a, %b 336 /// 337 /// Return = %a 338 /// Ops = llvm::dwarf::DW_OP_LLVM_arg0 llvm::dwarf::DW_OP_add 339 /// AdditionalValues = %b 340 Value *salvageDebugInfoImpl(Instruction &I, uint64_t CurrentLocOps, 341 SmallVectorImpl<uint64_t> &Ops, 342 SmallVectorImpl<Value *> &AdditionalValues); 343 344 /// Point debug users of \p From to \p To or salvage them. Use this function 345 /// only when replacing all uses of \p From with \p To, with a guarantee that 346 /// \p From is going to be deleted. 347 /// 348 /// Follow these rules to prevent use-before-def of \p To: 349 /// . If \p To is a linked Instruction, set \p DomPoint to \p To. 350 /// . If \p To is an unlinked Instruction, set \p DomPoint to the Instruction 351 /// \p To will be inserted after. 352 /// . If \p To is not an Instruction (e.g a Constant), the choice of 353 /// \p DomPoint is arbitrary. Pick \p From for simplicity. 354 /// 355 /// If a debug user cannot be preserved without reordering variable updates or 356 /// introducing a use-before-def, it is either salvaged (\ref salvageDebugInfo) 357 /// or deleted. Returns true if any debug users were updated. 358 bool replaceAllDbgUsesWith(Instruction &From, Value &To, Instruction &DomPoint, 359 DominatorTree &DT); 360 361 /// If a terminator in an unreachable basic block has an operand of type 362 /// Instruction, transform it into poison. Return true if any operands 363 /// are changed to poison. Original Values prior to being changed to poison 364 /// are returned in \p PoisonedValues. 365 bool handleUnreachableTerminator(Instruction *I, 366 SmallVectorImpl<Value *> &PoisonedValues); 367 368 /// Remove all instructions from a basic block other than its terminator 369 /// and any present EH pad instructions. Returns a pair where the first element 370 /// is the number of instructions (excluding debug info intrinsics) that have 371 /// been removed, and the second element is the number of debug info intrinsics 372 /// that have been removed. 373 std::pair<unsigned, unsigned> 374 removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB); 375 376 /// Insert an unreachable instruction before the specified 377 /// instruction, making it and the rest of the code in the block dead. 378 unsigned changeToUnreachable(Instruction *I, bool PreserveLCSSA = false, 379 DomTreeUpdater *DTU = nullptr, 380 MemorySSAUpdater *MSSAU = nullptr); 381 382 /// Convert the CallInst to InvokeInst with the specified unwind edge basic 383 /// block. This also splits the basic block where CI is located, because 384 /// InvokeInst is a terminator instruction. Returns the newly split basic 385 /// block. 386 BasicBlock *changeToInvokeAndSplitBasicBlock(CallInst *CI, 387 BasicBlock *UnwindEdge, 388 DomTreeUpdater *DTU = nullptr); 389 390 /// Replace 'BB's terminator with one that does not have an unwind successor 391 /// block. Rewrites `invoke` to `call`, etc. Updates any PHIs in unwind 392 /// successor. Returns the instruction that replaced the original terminator, 393 /// which might be a call in case the original terminator was an invoke. 394 /// 395 /// \param BB Block whose terminator will be replaced. Its terminator must 396 /// have an unwind successor. 397 Instruction *removeUnwindEdge(BasicBlock *BB, DomTreeUpdater *DTU = nullptr); 398 399 /// Remove all blocks that can not be reached from the function's entry. 400 /// 401 /// Returns true if any basic block was removed. 402 bool removeUnreachableBlocks(Function &F, DomTreeUpdater *DTU = nullptr, 403 MemorySSAUpdater *MSSAU = nullptr); 404 405 /// Combine the metadata of two instructions so that K can replace J. Some 406 /// metadata kinds can only be kept if K does not move, meaning it dominated 407 /// J in the original IR. 408 /// 409 /// Metadata not listed as known via KnownIDs is removed 410 void combineMetadata(Instruction *K, const Instruction *J, 411 ArrayRef<unsigned> KnownIDs, bool DoesKMove); 412 413 /// Combine the metadata of two instructions so that K can replace J. This 414 /// specifically handles the case of CSE-like transformations. Some 415 /// metadata can only be kept if K dominates J. For this to be correct, 416 /// K cannot be hoisted. 417 /// 418 /// Unknown metadata is removed. 419 void combineMetadataForCSE(Instruction *K, const Instruction *J, 420 bool DoesKMove); 421 422 /// Copy the metadata from the source instruction to the destination (the 423 /// replacement for the source instruction). 424 void copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source); 425 426 /// Patch the replacement so that it is not more restrictive than the value 427 /// being replaced. It assumes that the replacement does not get moved from 428 /// its original position. 429 void patchReplacementInstruction(Instruction *I, Value *Repl); 430 431 // Replace each use of 'From' with 'To', if that use does not belong to basic 432 // block where 'From' is defined. Returns the number of replacements made. 433 unsigned replaceNonLocalUsesWith(Instruction *From, Value *To); 434 435 /// Replace each use of 'From' with 'To' if that use is dominated by 436 /// the given edge. Returns the number of replacements made. 437 unsigned replaceDominatedUsesWith(Value *From, Value *To, DominatorTree &DT, 438 const BasicBlockEdge &Edge); 439 /// Replace each use of 'From' with 'To' if that use is dominated by 440 /// the end of the given BasicBlock. Returns the number of replacements made. 441 unsigned replaceDominatedUsesWith(Value *From, Value *To, DominatorTree &DT, 442 const BasicBlock *BB); 443 /// Replace each use of 'From' with 'To' if that use is dominated by 444 /// the given edge and the callback ShouldReplace returns true. Returns the 445 /// number of replacements made. 446 unsigned replaceDominatedUsesWithIf( 447 Value *From, Value *To, DominatorTree &DT, const BasicBlockEdge &Edge, 448 function_ref<bool(const Use &U, const Value *To)> ShouldReplace); 449 /// Replace each use of 'From' with 'To' if that use is dominated by 450 /// the end of the given BasicBlock and the callback ShouldReplace returns true. 451 /// Returns the number of replacements made. 452 unsigned replaceDominatedUsesWithIf( 453 Value *From, Value *To, DominatorTree &DT, const BasicBlock *BB, 454 function_ref<bool(const Use &U, const Value *To)> ShouldReplace); 455 456 /// Return true if this call calls a gc leaf function. 457 /// 458 /// A leaf function is a function that does not safepoint the thread during its 459 /// execution. During a call or invoke to such a function, the callers stack 460 /// does not have to be made parseable. 461 /// 462 /// Most passes can and should ignore this information, and it is only used 463 /// during lowering by the GC infrastructure. 464 bool callsGCLeafFunction(const CallBase *Call, const TargetLibraryInfo &TLI); 465 466 /// Copy a nonnull metadata node to a new load instruction. 467 /// 468 /// This handles mapping it to range metadata if the new load is an integer 469 /// load instead of a pointer load. 470 void copyNonnullMetadata(const LoadInst &OldLI, MDNode *N, LoadInst &NewLI); 471 472 /// Copy a range metadata node to a new load instruction. 473 /// 474 /// This handles mapping it to nonnull metadata if the new load is a pointer 475 /// load instead of an integer load and the range doesn't cover null. 476 void copyRangeMetadata(const DataLayout &DL, const LoadInst &OldLI, MDNode *N, 477 LoadInst &NewLI); 478 479 /// Remove the debug intrinsic instructions for the given instruction. 480 void dropDebugUsers(Instruction &I); 481 482 /// Hoist all of the instructions in the \p IfBlock to the dominant block 483 /// \p DomBlock, by moving its instructions to the insertion point \p InsertPt. 484 /// 485 /// The moved instructions receive the insertion point debug location values 486 /// (DILocations) and their debug intrinsic instructions are removed. 487 void hoistAllInstructionsInto(BasicBlock *DomBlock, Instruction *InsertPt, 488 BasicBlock *BB); 489 490 /// Given a constant, create a debug information expression. 491 DIExpression *getExpressionForConstant(DIBuilder &DIB, const Constant &C, 492 Type &Ty); 493 494 /// Remap the operands of the debug records attached to \p Inst, and the 495 /// operands of \p Inst itself if it's a debug intrinsic. 496 void remapDebugVariable(ValueToValueMapTy &Mapping, Instruction *Inst); 497 498 //===----------------------------------------------------------------------===// 499 // Intrinsic pattern matching 500 // 501 502 /// Try to match a bswap or bitreverse idiom. 503 /// 504 /// If an idiom is matched, an intrinsic call is inserted before \c I. Any added 505 /// instructions are returned in \c InsertedInsts. They will all have been added 506 /// to a basic block. 507 /// 508 /// A bitreverse idiom normally requires around 2*BW nodes to be searched (where 509 /// BW is the bitwidth of the integer type). A bswap idiom requires anywhere up 510 /// to BW / 4 nodes to be searched, so is significantly faster. 511 /// 512 /// This function returns true on a successful match or false otherwise. 513 bool recognizeBSwapOrBitReverseIdiom( 514 Instruction *I, bool MatchBSwaps, bool MatchBitReversals, 515 SmallVectorImpl<Instruction *> &InsertedInsts); 516 517 //===----------------------------------------------------------------------===// 518 // Sanitizer utilities 519 // 520 521 /// Given a CallInst, check if it calls a string function known to CodeGen, 522 /// and mark it with NoBuiltin if so. To be used by sanitizers that intend 523 /// to intercept string functions and want to avoid converting them to target 524 /// specific instructions. 525 void maybeMarkSanitizerLibraryCallNoBuiltin(CallInst *CI, 526 const TargetLibraryInfo *TLI); 527 528 //===----------------------------------------------------------------------===// 529 // Transform predicates 530 // 531 532 /// Given an instruction, is it legal to set operand OpIdx to a non-constant 533 /// value? 534 bool canReplaceOperandWithVariable(const Instruction *I, unsigned OpIdx); 535 536 //===----------------------------------------------------------------------===// 537 // Value helper functions 538 // 539 540 /// Invert the given true/false value, possibly reusing an existing copy. 541 Value *invertCondition(Value *Condition); 542 543 544 //===----------------------------------------------------------------------===// 545 // Assorted 546 // 547 548 /// If we can infer one attribute from another on the declaration of a 549 /// function, explicitly materialize the maximal set in the IR. 550 bool inferAttributesFromOthers(Function &F); 551 552 } // end namespace llvm 553 554 #endif // LLVM_TRANSFORMS_UTILS_LOCAL_H 555