xref: /freebsd/contrib/llvm-project/llvm/include/llvm/Transforms/Utils/Local.h (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
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