LLVM  9.0.0svn
MergeFunctions.cpp
Go to the documentation of this file.
1 //===- MergeFunctions.cpp - Merge identical functions ---------------------===//
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 pass looks for equivalent functions that are mergable and folds them.
11 //
12 // Order relation is defined on set of functions. It was made through
13 // special function comparison procedure that returns
14 // 0 when functions are equal,
15 // -1 when Left function is less than right function, and
16 // 1 for opposite case. We need total-ordering, so we need to maintain
17 // four properties on the functions set:
18 // a <= a (reflexivity)
19 // if a <= b and b <= a then a = b (antisymmetry)
20 // if a <= b and b <= c then a <= c (transitivity).
21 // for all a and b: a <= b or b <= a (totality).
22 //
23 // Comparison iterates through each instruction in each basic block.
24 // Functions are kept on binary tree. For each new function F we perform
25 // lookup in binary tree.
26 // In practice it works the following way:
27 // -- We define Function* container class with custom "operator<" (FunctionPtr).
28 // -- "FunctionPtr" instances are stored in std::set collection, so every
29 // std::set::insert operation will give you result in log(N) time.
30 //
31 // As an optimization, a hash of the function structure is calculated first, and
32 // two functions are only compared if they have the same hash. This hash is
33 // cheap to compute, and has the property that if function F == G according to
34 // the comparison function, then hash(F) == hash(G). This consistency property
35 // is critical to ensuring all possible merging opportunities are exploited.
36 // Collisions in the hash affect the speed of the pass but not the correctness
37 // or determinism of the resulting transformation.
38 //
39 // When a match is found the functions are folded. If both functions are
40 // overridable, we move the functionality into a new internal function and
41 // leave two overridable thunks to it.
42 //
43 //===----------------------------------------------------------------------===//
44 //
45 // Future work:
46 //
47 // * virtual functions.
48 //
49 // Many functions have their address taken by the virtual function table for
50 // the object they belong to. However, as long as it's only used for a lookup
51 // and call, this is irrelevant, and we'd like to fold such functions.
52 //
53 // * be smarter about bitcasts.
54 //
55 // In order to fold functions, we will sometimes add either bitcast instructions
56 // or bitcast constant expressions. Unfortunately, this can confound further
57 // analysis since the two functions differ where one has a bitcast and the
58 // other doesn't. We should learn to look through bitcasts.
59 //
60 // * Compare complex types with pointer types inside.
61 // * Compare cross-reference cases.
62 // * Compare complex expressions.
63 //
64 // All the three issues above could be described as ability to prove that
65 // fA == fB == fC == fE == fF == fG in example below:
66 //
67 // void fA() {
68 // fB();
69 // }
70 // void fB() {
71 // fA();
72 // }
73 //
74 // void fE() {
75 // fF();
76 // }
77 // void fF() {
78 // fG();
79 // }
80 // void fG() {
81 // fE();
82 // }
83 //
84 // Simplest cross-reference case (fA <--> fB) was implemented in previous
85 // versions of MergeFunctions, though it presented only in two function pairs
86 // in test-suite (that counts >50k functions)
87 // Though possibility to detect complex cross-referencing (e.g.: A->B->C->D->A)
88 // could cover much more cases.
89 //
90 //===----------------------------------------------------------------------===//
91 
92 #include "llvm/ADT/ArrayRef.h"
93 #include "llvm/ADT/SmallPtrSet.h"
94 #include "llvm/ADT/SmallVector.h"
95 #include "llvm/ADT/Statistic.h"
96 #include "llvm/IR/Argument.h"
97 #include "llvm/IR/Attributes.h"
98 #include "llvm/IR/BasicBlock.h"
99 #include "llvm/IR/CallSite.h"
100 #include "llvm/IR/Constant.h"
101 #include "llvm/IR/Constants.h"
103 #include "llvm/IR/DebugLoc.h"
104 #include "llvm/IR/DerivedTypes.h"
105 #include "llvm/IR/Function.h"
106 #include "llvm/IR/GlobalValue.h"
107 #include "llvm/IR/IRBuilder.h"
108 #include "llvm/IR/InstrTypes.h"
109 #include "llvm/IR/Instruction.h"
110 #include "llvm/IR/Instructions.h"
111 #include "llvm/IR/IntrinsicInst.h"
112 #include "llvm/IR/Module.h"
113 #include "llvm/IR/Type.h"
114 #include "llvm/IR/Use.h"
115 #include "llvm/IR/User.h"
116 #include "llvm/IR/Value.h"
117 #include "llvm/IR/ValueHandle.h"
118 #include "llvm/IR/ValueMap.h"
119 #include "llvm/Pass.h"
120 #include "llvm/Support/Casting.h"
122 #include "llvm/Support/Debug.h"
124 #include "llvm/Transforms/IPO.h"
126 #include <algorithm>
127 #include <cassert>
128 #include <iterator>
129 #include <set>
130 #include <utility>
131 #include <vector>
132 
133 using namespace llvm;
134 
135 #define DEBUG_TYPE "mergefunc"
136 
137 STATISTIC(NumFunctionsMerged, "Number of functions merged");
138 STATISTIC(NumThunksWritten, "Number of thunks generated");
139 STATISTIC(NumAliasesWritten, "Number of aliases generated");
140 STATISTIC(NumDoubleWeak, "Number of new functions created");
141 
143  "mergefunc-sanity",
144  cl::desc("How many functions in module could be used for "
145  "MergeFunctions pass sanity check. "
146  "'0' disables this check. Works only with '-debug' key."),
147  cl::init(0), cl::Hidden);
148 
149 // Under option -mergefunc-preserve-debug-info we:
150 // - Do not create a new function for a thunk.
151 // - Retain the debug info for a thunk's parameters (and associated
152 // instructions for the debug info) from the entry block.
153 // Note: -debug will display the algorithm at work.
154 // - Create debug-info for the call (to the shared implementation) made by
155 // a thunk and its return value.
156 // - Erase the rest of the function, retaining the (minimally sized) entry
157 // block to create a thunk.
158 // - Preserve a thunk's call site to point to the thunk even when both occur
159 // within the same translation unit, to aid debugability. Note that this
160 // behaviour differs from the underlying -mergefunc implementation which
161 // modifies the thunk's call site to point to the shared implementation
162 // when both occur within the same translation unit.
163 static cl::opt<bool>
164  MergeFunctionsPDI("mergefunc-preserve-debug-info", cl::Hidden,
165  cl::init(false),
166  cl::desc("Preserve debug info in thunk when mergefunc "
167  "transformations are made."));
168 
169 static cl::opt<bool>
170  MergeFunctionsAliases("mergefunc-use-aliases", cl::Hidden,
171  cl::init(false),
172  cl::desc("Allow mergefunc to create aliases"));
173 
174 namespace {
175 
176 class FunctionNode {
177  mutable AssertingVH<Function> F;
179 
180 public:
181  // Note the hash is recalculated potentially multiple times, but it is cheap.
182  FunctionNode(Function *F)
183  : F(F), Hash(FunctionComparator::functionHash(*F)) {}
184 
185  Function *getFunc() const { return F; }
186  FunctionComparator::FunctionHash getHash() const { return Hash; }
187 
188  /// Replace the reference to the function F by the function G, assuming their
189  /// implementations are equal.
190  void replaceBy(Function *G) const {
191  F = G;
192  }
193 
194  void release() { F = nullptr; }
195 };
196 
197 /// MergeFunctions finds functions which will generate identical machine code,
198 /// by considering all pointer types to be equivalent. Once identified,
199 /// MergeFunctions will fold them by replacing a call to one to a call to a
200 /// bitcast of the other.
201 class MergeFunctions : public ModulePass {
202 public:
203  static char ID;
204 
205  MergeFunctions()
206  : ModulePass(ID), FnTree(FunctionNodeCmp(&GlobalNumbers)) {
208  }
209 
210  bool runOnModule(Module &M) override;
211 
212 private:
213  // The function comparison operator is provided here so that FunctionNodes do
214  // not need to become larger with another pointer.
215  class FunctionNodeCmp {
216  GlobalNumberState* GlobalNumbers;
217 
218  public:
219  FunctionNodeCmp(GlobalNumberState* GN) : GlobalNumbers(GN) {}
220 
221  bool operator()(const FunctionNode &LHS, const FunctionNode &RHS) const {
222  // Order first by hashes, then full function comparison.
223  if (LHS.getHash() != RHS.getHash())
224  return LHS.getHash() < RHS.getHash();
225  FunctionComparator FCmp(LHS.getFunc(), RHS.getFunc(), GlobalNumbers);
226  return FCmp.compare() == -1;
227  }
228  };
229  using FnTreeType = std::set<FunctionNode, FunctionNodeCmp>;
230 
231  GlobalNumberState GlobalNumbers;
232 
233  /// A work queue of functions that may have been modified and should be
234  /// analyzed again.
235  std::vector<WeakTrackingVH> Deferred;
236 
237 #ifndef NDEBUG
238  /// Checks the rules of order relation introduced among functions set.
239  /// Returns true, if sanity check has been passed, and false if failed.
240  bool doSanityCheck(std::vector<WeakTrackingVH> &Worklist);
241 #endif
242 
243  /// Insert a ComparableFunction into the FnTree, or merge it away if it's
244  /// equal to one that's already present.
245  bool insert(Function *NewFunction);
246 
247  /// Remove a Function from the FnTree and queue it up for a second sweep of
248  /// analysis.
249  void remove(Function *F);
250 
251  /// Find the functions that use this Value and remove them from FnTree and
252  /// queue the functions.
253  void removeUsers(Value *V);
254 
255  /// Replace all direct calls of Old with calls of New. Will bitcast New if
256  /// necessary to make types match.
257  void replaceDirectCallers(Function *Old, Function *New);
258 
259  /// Merge two equivalent functions. Upon completion, G may be deleted, or may
260  /// be converted into a thunk. In either case, it should never be visited
261  /// again.
262  void mergeTwoFunctions(Function *F, Function *G);
263 
264  /// Fill PDIUnrelatedWL with instructions from the entry block that are
265  /// unrelated to parameter related debug info.
266  void filterInstsUnrelatedToPDI(BasicBlock *GEntryBlock,
267  std::vector<Instruction *> &PDIUnrelatedWL);
268 
269  /// Erase the rest of the CFG (i.e. barring the entry block).
270  void eraseTail(Function *G);
271 
272  /// Erase the instructions in PDIUnrelatedWL as they are unrelated to the
273  /// parameter debug info, from the entry block.
274  void eraseInstsUnrelatedToPDI(std::vector<Instruction *> &PDIUnrelatedWL);
275 
276  /// Replace G with a simple tail call to bitcast(F). Also (unless
277  /// MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
278  /// delete G.
279  void writeThunk(Function *F, Function *G);
280 
281  // Replace G with an alias to F (deleting function G)
282  void writeAlias(Function *F, Function *G);
283 
284  // Replace G with an alias to F if possible, or a thunk to F if possible.
285  // Returns false if neither is the case.
286  bool writeThunkOrAlias(Function *F, Function *G);
287 
288  /// Replace function F with function G in the function tree.
289  void replaceFunctionInTree(const FunctionNode &FN, Function *G);
290 
291  /// The set of all distinct functions. Use the insert() and remove() methods
292  /// to modify it. The map allows efficient lookup and deferring of Functions.
293  FnTreeType FnTree;
294 
295  // Map functions to the iterators of the FunctionNode which contains them
296  // in the FnTree. This must be updated carefully whenever the FnTree is
297  // modified, i.e. in insert(), remove(), and replaceFunctionInTree(), to avoid
298  // dangling iterators into FnTree. The invariant that preserves this is that
299  // there is exactly one mapping F -> FN for each FunctionNode FN in FnTree.
300  DenseMap<AssertingVH<Function>, FnTreeType::iterator> FNodesInTree;
301 };
302 
303 } // end anonymous namespace
304 
305 char MergeFunctions::ID = 0;
306 
307 INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)
308 
310  return new MergeFunctions();
311 }
312 
313 #ifndef NDEBUG
314 bool MergeFunctions::doSanityCheck(std::vector<WeakTrackingVH> &Worklist) {
315  if (const unsigned Max = NumFunctionsForSanityCheck) {
316  unsigned TripleNumber = 0;
317  bool Valid = true;
318 
319  dbgs() << "MERGEFUNC-SANITY: Started for first " << Max << " functions.\n";
320 
321  unsigned i = 0;
322  for (std::vector<WeakTrackingVH>::iterator I = Worklist.begin(),
323  E = Worklist.end();
324  I != E && i < Max; ++I, ++i) {
325  unsigned j = i;
326  for (std::vector<WeakTrackingVH>::iterator J = I; J != E && j < Max;
327  ++J, ++j) {
328  Function *F1 = cast<Function>(*I);
329  Function *F2 = cast<Function>(*J);
330  int Res1 = FunctionComparator(F1, F2, &GlobalNumbers).compare();
331  int Res2 = FunctionComparator(F2, F1, &GlobalNumbers).compare();
332 
333  // If F1 <= F2, then F2 >= F1, otherwise report failure.
334  if (Res1 != -Res2) {
335  dbgs() << "MERGEFUNC-SANITY: Non-symmetric; triple: " << TripleNumber
336  << "\n";
337  dbgs() << *F1 << '\n' << *F2 << '\n';
338  Valid = false;
339  }
340 
341  if (Res1 == 0)
342  continue;
343 
344  unsigned k = j;
345  for (std::vector<WeakTrackingVH>::iterator K = J; K != E && k < Max;
346  ++k, ++K, ++TripleNumber) {
347  if (K == J)
348  continue;
349 
350  Function *F3 = cast<Function>(*K);
351  int Res3 = FunctionComparator(F1, F3, &GlobalNumbers).compare();
352  int Res4 = FunctionComparator(F2, F3, &GlobalNumbers).compare();
353 
354  bool Transitive = true;
355 
356  if (Res1 != 0 && Res1 == Res4) {
357  // F1 > F2, F2 > F3 => F1 > F3
358  Transitive = Res3 == Res1;
359  } else if (Res3 != 0 && Res3 == -Res4) {
360  // F1 > F3, F3 > F2 => F1 > F2
361  Transitive = Res3 == Res1;
362  } else if (Res4 != 0 && -Res3 == Res4) {
363  // F2 > F3, F3 > F1 => F2 > F1
364  Transitive = Res4 == -Res1;
365  }
366 
367  if (!Transitive) {
368  dbgs() << "MERGEFUNC-SANITY: Non-transitive; triple: "
369  << TripleNumber << "\n";
370  dbgs() << "Res1, Res3, Res4: " << Res1 << ", " << Res3 << ", "
371  << Res4 << "\n";
372  dbgs() << *F1 << '\n' << *F2 << '\n' << *F3 << '\n';
373  Valid = false;
374  }
375  }
376  }
377  }
378 
379  dbgs() << "MERGEFUNC-SANITY: " << (Valid ? "Passed." : "Failed.") << "\n";
380  return Valid;
381  }
382  return true;
383 }
384 #endif
385 
386 /// Check whether \p F is eligible for function merging.
388  return !F.isDeclaration() && !F.hasAvailableExternallyLinkage();
389 }
390 
391 bool MergeFunctions::runOnModule(Module &M) {
392  if (skipModule(M))
393  return false;
394 
395  bool Changed = false;
396 
397  // All functions in the module, ordered by hash. Functions with a unique
398  // hash value are easily eliminated.
399  std::vector<std::pair<FunctionComparator::FunctionHash, Function *>>
400  HashedFuncs;
401  for (Function &Func : M) {
402  if (isEligibleForMerging(Func)) {
403  HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
404  }
405  }
406 
407  std::stable_sort(
408  HashedFuncs.begin(), HashedFuncs.end(),
409  [](const std::pair<FunctionComparator::FunctionHash, Function *> &a,
410  const std::pair<FunctionComparator::FunctionHash, Function *> &b) {
411  return a.first < b.first;
412  });
413 
414  auto S = HashedFuncs.begin();
415  for (auto I = HashedFuncs.begin(), IE = HashedFuncs.end(); I != IE; ++I) {
416  // If the hash value matches the previous value or the next one, we must
417  // consider merging it. Otherwise it is dropped and never considered again.
418  if ((I != S && std::prev(I)->first == I->first) ||
419  (std::next(I) != IE && std::next(I)->first == I->first) ) {
420  Deferred.push_back(WeakTrackingVH(I->second));
421  }
422  }
423 
424  do {
425  std::vector<WeakTrackingVH> Worklist;
426  Deferred.swap(Worklist);
427 
428  LLVM_DEBUG(doSanityCheck(Worklist));
429 
430  LLVM_DEBUG(dbgs() << "size of module: " << M.size() << '\n');
431  LLVM_DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n');
432 
433  // Insert functions and merge them.
434  for (WeakTrackingVH &I : Worklist) {
435  if (!I)
436  continue;
437  Function *F = cast<Function>(I);
438  if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage()) {
439  Changed |= insert(F);
440  }
441  }
442  LLVM_DEBUG(dbgs() << "size of FnTree: " << FnTree.size() << '\n');
443  } while (!Deferred.empty());
444 
445  FnTree.clear();
446  FNodesInTree.clear();
447  GlobalNumbers.clear();
448 
449  return Changed;
450 }
451 
452 // Replace direct callers of Old with New.
453 void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
454  Constant *BitcastNew = ConstantExpr::getBitCast(New, Old->getType());
455  for (auto UI = Old->use_begin(), UE = Old->use_end(); UI != UE;) {
456  Use *U = &*UI;
457  ++UI;
458  CallSite CS(U->getUser());
459  if (CS && CS.isCallee(U)) {
460  // Transfer the called function's attributes to the call site. Due to the
461  // bitcast we will 'lose' ABI changing attributes because the 'called
462  // function' is no longer a Function* but the bitcast. Code that looks up
463  // the attributes from the called function will fail.
464 
465  // FIXME: This is not actually true, at least not anymore. The callsite
466  // will always have the same ABI affecting attributes as the callee,
467  // because otherwise the original input has UB. Note that Old and New
468  // always have matching ABI, so no attributes need to be changed.
469  // Transferring other attributes may help other optimizations, but that
470  // should be done uniformly and not in this ad-hoc way.
471  auto &Context = New->getContext();
472  auto NewPAL = New->getAttributes();
473  SmallVector<AttributeSet, 4> NewArgAttrs;
474  for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++)
475  NewArgAttrs.push_back(NewPAL.getParamAttributes(argIdx));
476  // Don't transfer attributes from the function to the callee. Function
477  // attributes typically aren't relevant to the calling convention or ABI.
478  CS.setAttributes(AttributeList::get(Context, /*FnAttrs=*/AttributeSet(),
479  NewPAL.getRetAttributes(),
480  NewArgAttrs));
481 
482  remove(CS.getInstruction()->getFunction());
483  U->set(BitcastNew);
484  }
485  }
486 }
487 
488 // Helper for writeThunk,
489 // Selects proper bitcast operation,
490 // but a bit simpler then CastInst::getCastOpcode.
491 static Value *createCast(IRBuilder<> &Builder, Value *V, Type *DestTy) {
492  Type *SrcTy = V->getType();
493  if (SrcTy->isStructTy()) {
494  assert(DestTy->isStructTy());
495  assert(SrcTy->getStructNumElements() == DestTy->getStructNumElements());
496  Value *Result = UndefValue::get(DestTy);
497  for (unsigned int I = 0, E = SrcTy->getStructNumElements(); I < E; ++I) {
498  Value *Element = createCast(
499  Builder, Builder.CreateExtractValue(V, makeArrayRef(I)),
500  DestTy->getStructElementType(I));
501 
502  Result =
503  Builder.CreateInsertValue(Result, Element, makeArrayRef(I));
504  }
505  return Result;
506  }
507  assert(!DestTy->isStructTy());
508  if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
509  return Builder.CreateIntToPtr(V, DestTy);
510  else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
511  return Builder.CreatePtrToInt(V, DestTy);
512  else
513  return Builder.CreateBitCast(V, DestTy);
514 }
515 
516 // Erase the instructions in PDIUnrelatedWL as they are unrelated to the
517 // parameter debug info, from the entry block.
518 void MergeFunctions::eraseInstsUnrelatedToPDI(
519  std::vector<Instruction *> &PDIUnrelatedWL) {
520  LLVM_DEBUG(
521  dbgs() << " Erasing instructions (in reverse order of appearance in "
522  "entry block) unrelated to parameter debug info from entry "
523  "block: {\n");
524  while (!PDIUnrelatedWL.empty()) {
525  Instruction *I = PDIUnrelatedWL.back();
526  LLVM_DEBUG(dbgs() << " Deleting Instruction: ");
527  LLVM_DEBUG(I->print(dbgs()));
528  LLVM_DEBUG(dbgs() << "\n");
529  I->eraseFromParent();
530  PDIUnrelatedWL.pop_back();
531  }
532  LLVM_DEBUG(dbgs() << " } // Done erasing instructions unrelated to parameter "
533  "debug info from entry block. \n");
534 }
535 
536 // Reduce G to its entry block.
537 void MergeFunctions::eraseTail(Function *G) {
538  std::vector<BasicBlock *> WorklistBB;
539  for (Function::iterator BBI = std::next(G->begin()), BBE = G->end();
540  BBI != BBE; ++BBI) {
541  BBI->dropAllReferences();
542  WorklistBB.push_back(&*BBI);
543  }
544  while (!WorklistBB.empty()) {
545  BasicBlock *BB = WorklistBB.back();
546  BB->eraseFromParent();
547  WorklistBB.pop_back();
548  }
549 }
550 
551 // We are interested in the following instructions from the entry block as being
552 // related to parameter debug info:
553 // - @llvm.dbg.declare
554 // - stores from the incoming parameters to locations on the stack-frame
555 // - allocas that create these locations on the stack-frame
556 // - @llvm.dbg.value
557 // - the entry block's terminator
558 // The rest are unrelated to debug info for the parameters; fill up
559 // PDIUnrelatedWL with such instructions.
560 void MergeFunctions::filterInstsUnrelatedToPDI(
561  BasicBlock *GEntryBlock, std::vector<Instruction *> &PDIUnrelatedWL) {
562  std::set<Instruction *> PDIRelated;
563  for (BasicBlock::iterator BI = GEntryBlock->begin(), BIE = GEntryBlock->end();
564  BI != BIE; ++BI) {
565  if (auto *DVI = dyn_cast<DbgValueInst>(&*BI)) {
566  LLVM_DEBUG(dbgs() << " Deciding: ");
567  LLVM_DEBUG(BI->print(dbgs()));
568  LLVM_DEBUG(dbgs() << "\n");
569  DILocalVariable *DILocVar = DVI->getVariable();
570  if (DILocVar->isParameter()) {
571  LLVM_DEBUG(dbgs() << " Include (parameter): ");
572  LLVM_DEBUG(BI->print(dbgs()));
573  LLVM_DEBUG(dbgs() << "\n");
574  PDIRelated.insert(&*BI);
575  } else {
576  LLVM_DEBUG(dbgs() << " Delete (!parameter): ");
577  LLVM_DEBUG(BI->print(dbgs()));
578  LLVM_DEBUG(dbgs() << "\n");
579  }
580  } else if (auto *DDI = dyn_cast<DbgDeclareInst>(&*BI)) {
581  LLVM_DEBUG(dbgs() << " Deciding: ");
582  LLVM_DEBUG(BI->print(dbgs()));
583  LLVM_DEBUG(dbgs() << "\n");
584  DILocalVariable *DILocVar = DDI->getVariable();
585  if (DILocVar->isParameter()) {
586  LLVM_DEBUG(dbgs() << " Parameter: ");
587  LLVM_DEBUG(DILocVar->print(dbgs()));
588  AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
589  if (AI) {
590  LLVM_DEBUG(dbgs() << " Processing alloca users: ");
591  LLVM_DEBUG(dbgs() << "\n");
592  for (User *U : AI->users()) {
593  if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
594  if (Value *Arg = SI->getValueOperand()) {
595  if (dyn_cast<Argument>(Arg)) {
596  LLVM_DEBUG(dbgs() << " Include: ");
597  LLVM_DEBUG(AI->print(dbgs()));
598  LLVM_DEBUG(dbgs() << "\n");
599  PDIRelated.insert(AI);
600  LLVM_DEBUG(dbgs() << " Include (parameter): ");
601  LLVM_DEBUG(SI->print(dbgs()));
602  LLVM_DEBUG(dbgs() << "\n");
603  PDIRelated.insert(SI);
604  LLVM_DEBUG(dbgs() << " Include: ");
605  LLVM_DEBUG(BI->print(dbgs()));
606  LLVM_DEBUG(dbgs() << "\n");
607  PDIRelated.insert(&*BI);
608  } else {
609  LLVM_DEBUG(dbgs() << " Delete (!parameter): ");
610  LLVM_DEBUG(SI->print(dbgs()));
611  LLVM_DEBUG(dbgs() << "\n");
612  }
613  }
614  } else {
615  LLVM_DEBUG(dbgs() << " Defer: ");
616  LLVM_DEBUG(U->print(dbgs()));
617  LLVM_DEBUG(dbgs() << "\n");
618  }
619  }
620  } else {
621  LLVM_DEBUG(dbgs() << " Delete (alloca NULL): ");
622  LLVM_DEBUG(BI->print(dbgs()));
623  LLVM_DEBUG(dbgs() << "\n");
624  }
625  } else {
626  LLVM_DEBUG(dbgs() << " Delete (!parameter): ");
627  LLVM_DEBUG(BI->print(dbgs()));
628  LLVM_DEBUG(dbgs() << "\n");
629  }
630  } else if (BI->isTerminator() && &*BI == GEntryBlock->getTerminator()) {
631  LLVM_DEBUG(dbgs() << " Will Include Terminator: ");
632  LLVM_DEBUG(BI->print(dbgs()));
633  LLVM_DEBUG(dbgs() << "\n");
634  PDIRelated.insert(&*BI);
635  } else {
636  LLVM_DEBUG(dbgs() << " Defer: ");
637  LLVM_DEBUG(BI->print(dbgs()));
638  LLVM_DEBUG(dbgs() << "\n");
639  }
640  }
641  LLVM_DEBUG(
642  dbgs()
643  << " Report parameter debug info related/related instructions: {\n");
644  for (BasicBlock::iterator BI = GEntryBlock->begin(), BE = GEntryBlock->end();
645  BI != BE; ++BI) {
646 
647  Instruction *I = &*BI;
648  if (PDIRelated.find(I) == PDIRelated.end()) {
649  LLVM_DEBUG(dbgs() << " !PDIRelated: ");
650  LLVM_DEBUG(I->print(dbgs()));
651  LLVM_DEBUG(dbgs() << "\n");
652  PDIUnrelatedWL.push_back(I);
653  } else {
654  LLVM_DEBUG(dbgs() << " PDIRelated: ");
655  LLVM_DEBUG(I->print(dbgs()));
656  LLVM_DEBUG(dbgs() << "\n");
657  }
658  }
659  LLVM_DEBUG(dbgs() << " }\n");
660 }
661 
662 /// Whether this function may be replaced by a forwarding thunk.
663 static bool canCreateThunkFor(Function *F) {
664  if (F->isVarArg())
665  return false;
666 
667  // Don't merge tiny functions using a thunk, since it can just end up
668  // making the function larger.
669  if (F->size() == 1) {
670  if (F->front().size() <= 2) {
671  LLVM_DEBUG(dbgs() << "canCreateThunkFor: " << F->getName()
672  << " is too small to bother creating a thunk for\n");
673  return false;
674  }
675  }
676  return true;
677 }
678 
679 // Replace G with a simple tail call to bitcast(F). Also (unless
680 // MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
681 // delete G. Under MergeFunctionsPDI, we use G itself for creating
682 // the thunk as we preserve the debug info (and associated instructions)
683 // from G's entry block pertaining to G's incoming arguments which are
684 // passed on as corresponding arguments in the call that G makes to F.
685 // For better debugability, under MergeFunctionsPDI, we do not modify G's
686 // call sites to point to F even when within the same translation unit.
687 void MergeFunctions::writeThunk(Function *F, Function *G) {
688  BasicBlock *GEntryBlock = nullptr;
689  std::vector<Instruction *> PDIUnrelatedWL;
690  BasicBlock *BB = nullptr;
691  Function *NewG = nullptr;
692  if (MergeFunctionsPDI) {
693  LLVM_DEBUG(dbgs() << "writeThunk: (MergeFunctionsPDI) Do not create a new "
694  "function as thunk; retain original: "
695  << G->getName() << "()\n");
696  GEntryBlock = &G->getEntryBlock();
697  LLVM_DEBUG(
698  dbgs() << "writeThunk: (MergeFunctionsPDI) filter parameter related "
699  "debug info for "
700  << G->getName() << "() {\n");
701  filterInstsUnrelatedToPDI(GEntryBlock, PDIUnrelatedWL);
702  GEntryBlock->getTerminator()->eraseFromParent();
703  BB = GEntryBlock;
704  } else {
705  NewG = Function::Create(G->getFunctionType(), G->getLinkage(),
706  G->getAddressSpace(), "", G->getParent());
707  BB = BasicBlock::Create(F->getContext(), "", NewG);
708  }
709 
710  IRBuilder<> Builder(BB);
711  Function *H = MergeFunctionsPDI ? G : NewG;
713  unsigned i = 0;
714  FunctionType *FFTy = F->getFunctionType();
715  for (Argument &AI : H->args()) {
716  Args.push_back(createCast(Builder, &AI, FFTy->getParamType(i)));
717  ++i;
718  }
719 
720  CallInst *CI = Builder.CreateCall(F, Args);
721  ReturnInst *RI = nullptr;
722  CI->setTailCall();
723  CI->setCallingConv(F->getCallingConv());
724  CI->setAttributes(F->getAttributes());
725  if (H->getReturnType()->isVoidTy()) {
726  RI = Builder.CreateRetVoid();
727  } else {
728  RI = Builder.CreateRet(createCast(Builder, CI, H->getReturnType()));
729  }
730 
731  if (MergeFunctionsPDI) {
732  DISubprogram *DIS = G->getSubprogram();
733  if (DIS) {
734  DebugLoc CIDbgLoc = DebugLoc::get(DIS->getScopeLine(), 0, DIS);
735  DebugLoc RIDbgLoc = DebugLoc::get(DIS->getScopeLine(), 0, DIS);
736  CI->setDebugLoc(CIDbgLoc);
737  RI->setDebugLoc(RIDbgLoc);
738  } else {
739  LLVM_DEBUG(
740  dbgs() << "writeThunk: (MergeFunctionsPDI) No DISubprogram for "
741  << G->getName() << "()\n");
742  }
743  eraseTail(G);
744  eraseInstsUnrelatedToPDI(PDIUnrelatedWL);
745  LLVM_DEBUG(
746  dbgs() << "} // End of parameter related debug info filtering for: "
747  << G->getName() << "()\n");
748  } else {
749  NewG->copyAttributesFrom(G);
750  NewG->takeName(G);
751  removeUsers(G);
752  G->replaceAllUsesWith(NewG);
753  G->eraseFromParent();
754  }
755 
756  LLVM_DEBUG(dbgs() << "writeThunk: " << H->getName() << '\n');
757  ++NumThunksWritten;
758 }
759 
760 // Whether this function may be replaced by an alias
761 static bool canCreateAliasFor(Function *F) {
763  return false;
764 
765  // We should only see linkages supported by aliases here
767  || F->hasWeakLinkage() || F->hasLinkOnceLinkage());
768  return true;
769 }
770 
771 // Replace G with an alias to F (deleting function G)
772 void MergeFunctions::writeAlias(Function *F, Function *G) {
773  Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
774  PointerType *PtrType = G->getType();
775  auto *GA = GlobalAlias::create(
776  PtrType->getElementType(), PtrType->getAddressSpace(),
777  G->getLinkage(), "", BitcastF, G->getParent());
778 
780  GA->takeName(G);
781  GA->setVisibility(G->getVisibility());
782  GA->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
783 
784  removeUsers(G);
785  G->replaceAllUsesWith(GA);
786  G->eraseFromParent();
787 
788  LLVM_DEBUG(dbgs() << "writeAlias: " << GA->getName() << '\n');
789  ++NumAliasesWritten;
790 }
791 
792 // Replace G with an alias to F if possible, or a thunk to F if
793 // profitable. Returns false if neither is the case.
794 bool MergeFunctions::writeThunkOrAlias(Function *F, Function *G) {
795  if (canCreateAliasFor(G)) {
796  writeAlias(F, G);
797  return true;
798  }
799  if (canCreateThunkFor(F)) {
800  writeThunk(F, G);
801  return true;
802  }
803  return false;
804 }
805 
806 // Merge two equivalent functions. Upon completion, Function G is deleted.
807 void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
808  if (F->isInterposable()) {
809  assert(G->isInterposable());
810 
811  // Both writeThunkOrAlias() calls below must succeed, either because we can
812  // create aliases for G and NewF, or because a thunk for F is profitable.
813  // F here has the same signature as NewF below, so that's what we check.
814  if (!canCreateThunkFor(F) &&
816  return;
817 
818  // Make them both thunks to the same internal function.
820  F->getAddressSpace(), "", F->getParent());
821  NewF->copyAttributesFrom(F);
822  NewF->takeName(F);
823  removeUsers(F);
824  F->replaceAllUsesWith(NewF);
825 
826  unsigned MaxAlignment = std::max(G->getAlignment(), NewF->getAlignment());
827 
828  writeThunkOrAlias(F, G);
829  writeThunkOrAlias(F, NewF);
830 
831  F->setAlignment(MaxAlignment);
833  ++NumDoubleWeak;
834  ++NumFunctionsMerged;
835  } else {
836  // For better debugability, under MergeFunctionsPDI, we do not modify G's
837  // call sites to point to F even when within the same translation unit.
838  if (!G->isInterposable() && !MergeFunctionsPDI) {
839  if (G->hasGlobalUnnamedAddr()) {
840  // G might have been a key in our GlobalNumberState, and it's illegal
841  // to replace a key in ValueMap<GlobalValue *> with a non-global.
842  GlobalNumbers.erase(G);
843  // If G's address is not significant, replace it entirely.
844  Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
845  removeUsers(G);
846  G->replaceAllUsesWith(BitcastF);
847  } else {
848  // Redirect direct callers of G to F. (See note on MergeFunctionsPDI
849  // above).
850  replaceDirectCallers(G, F);
851  }
852  }
853 
854  // If G was internal then we may have replaced all uses of G with F. If so,
855  // stop here and delete G. There's no need for a thunk. (See note on
856  // MergeFunctionsPDI above).
857  if (G->isDiscardableIfUnused() && G->use_empty() && !MergeFunctionsPDI) {
858  G->eraseFromParent();
859  ++NumFunctionsMerged;
860  return;
861  }
862 
863  if (writeThunkOrAlias(F, G)) {
864  ++NumFunctionsMerged;
865  }
866  }
867 }
868 
869 /// Replace function F by function G.
870 void MergeFunctions::replaceFunctionInTree(const FunctionNode &FN,
871  Function *G) {
872  Function *F = FN.getFunc();
873  assert(FunctionComparator(F, G, &GlobalNumbers).compare() == 0 &&
874  "The two functions must be equal");
875 
876  auto I = FNodesInTree.find(F);
877  assert(I != FNodesInTree.end() && "F should be in FNodesInTree");
878  assert(FNodesInTree.count(G) == 0 && "FNodesInTree should not contain G");
879 
880  FnTreeType::iterator IterToFNInFnTree = I->second;
881  assert(&(*IterToFNInFnTree) == &FN && "F should map to FN in FNodesInTree.");
882  // Remove F -> FN and insert G -> FN
883  FNodesInTree.erase(I);
884  FNodesInTree.insert({G, IterToFNInFnTree});
885  // Replace F with G in FN, which is stored inside the FnTree.
886  FN.replaceBy(G);
887 }
888 
889 // Ordering for functions that are equal under FunctionComparator
890 static bool isFuncOrderCorrect(const Function *F, const Function *G) {
891  if (F->isInterposable() != G->isInterposable()) {
892  // Strong before weak, because the weak function may call the strong
893  // one, but not the other way around.
894  return !F->isInterposable();
895  }
896  if (F->hasLocalLinkage() != G->hasLocalLinkage()) {
897  // External before local, because we definitely have to keep the external
898  // function, but may be able to drop the local one.
899  return !F->hasLocalLinkage();
900  }
901  // Impose a total order (by name) on the replacement of functions. This is
902  // important when operating on more than one module independently to prevent
903  // cycles of thunks calling each other when the modules are linked together.
904  return F->getName() <= G->getName();
905 }
906 
907 // Insert a ComparableFunction into the FnTree, or merge it away if equal to one
908 // that was already inserted.
909 bool MergeFunctions::insert(Function *NewFunction) {
910  std::pair<FnTreeType::iterator, bool> Result =
911  FnTree.insert(FunctionNode(NewFunction));
912 
913  if (Result.second) {
914  assert(FNodesInTree.count(NewFunction) == 0);
915  FNodesInTree.insert({NewFunction, Result.first});
916  LLVM_DEBUG(dbgs() << "Inserting as unique: " << NewFunction->getName()
917  << '\n');
918  return false;
919  }
920 
921  const FunctionNode &OldF = *Result.first;
922 
923  if (!isFuncOrderCorrect(OldF.getFunc(), NewFunction)) {
924  // Swap the two functions.
925  Function *F = OldF.getFunc();
926  replaceFunctionInTree(*Result.first, NewFunction);
927  NewFunction = F;
928  assert(OldF.getFunc() != F && "Must have swapped the functions.");
929  }
930 
931  LLVM_DEBUG(dbgs() << " " << OldF.getFunc()->getName()
932  << " == " << NewFunction->getName() << '\n');
933 
934  Function *DeleteF = NewFunction;
935  mergeTwoFunctions(OldF.getFunc(), DeleteF);
936  return true;
937 }
938 
939 // Remove a function from FnTree. If it was already in FnTree, add
940 // it to Deferred so that we'll look at it in the next round.
942  auto I = FNodesInTree.find(F);
943  if (I != FNodesInTree.end()) {
944  LLVM_DEBUG(dbgs() << "Deferred " << F->getName() << ".\n");
945  FnTree.erase(I->second);
946  // I->second has been invalidated, remove it from the FNodesInTree map to
947  // preserve the invariant.
948  FNodesInTree.erase(I);
949  Deferred.emplace_back(F);
950  }
951 }
952 
953 // For each instruction used by the value, remove() the function that contains
954 // the instruction. This should happen right before a call to RAUW.
955 void MergeFunctions::removeUsers(Value *V) {
956  std::vector<Value *> Worklist;
957  Worklist.push_back(V);
958  SmallPtrSet<Value*, 8> Visited;
959  Visited.insert(V);
960  while (!Worklist.empty()) {
961  Value *V = Worklist.back();
962  Worklist.pop_back();
963 
964  for (User *U : V->users()) {
965  if (Instruction *I = dyn_cast<Instruction>(U)) {
966  remove(I->getFunction());
967  } else if (isa<GlobalValue>(U)) {
968  // do nothing
969  } else if (Constant *C = dyn_cast<Constant>(U)) {
970  for (User *UU : C->users()) {
971  if (!Visited.insert(UU).second)
972  Worklist.push_back(UU);
973  }
974  }
975  }
976  }
977 }
size_t size() const
Definition: Function.h:661
bool isVarArg() const
isVarArg - Return true if this function takes a variable number of arguments.
Definition: Function.h:177
uint64_t CallInst * C
Return a value (possibly void), from a function.
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:68
unsigned getAlignment() const
Definition: GlobalObject.h:59
use_iterator use_end()
Definition: Value.h:347
bool hasLocalLinkage() const
Definition: GlobalValue.h:436
DILocation * get() const
Get the underlying DILocation.
Definition: DebugLoc.cpp:22
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
This class represents an incoming formal argument to a Function.
Definition: Argument.h:30
LLVMContext & Context
static Value * createCast(IRBuilder<> &Builder, Value *V, Type *DestTy)
This class represents lattice values for constants.
Definition: AllocatorList.h:24
Type * getParamType(unsigned i) const
Parameter type accessors.
Definition: DerivedTypes.h:135
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:65
iterator end()
Definition: Function.h:658
std::error_code remove(const Twine &path, bool IgnoreNonExisting=true)
Remove path.
ModulePass * createMergeFunctionsPass()
createMergeFunctionsPass - This pass discovers identical functions and collapses them.
static bool isFuncOrderCorrect(const Function *F, const Function *G)
This class represents a function call, abstracting a target machine&#39;s calling convention.
bool hasAvailableExternallyLinkage() const
Definition: GlobalValue.h:423
Like Internal, but omit from symbol table.
Definition: GlobalValue.h:57
bool isInterposable() const
Return true if this global&#39;s definition can be substituted with an arbitrary definition at link time...
Definition: GlobalValue.h:420
STATISTIC(NumFunctions, "Total number of functions")
A debug info location.
Definition: DebugLoc.h:34
F(f)
Type * getStructElementType(unsigned N) const
Definition: DerivedTypes.h:333
const Instruction * getTerminator() const LLVM_READONLY
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:138
This defines the Use class.
void setAlignment(unsigned Align)
Definition: Globals.cpp:116
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:269
uint64_t FunctionHash
Hash a function.
static bool isEligibleForMerging(Function &F)
Check whether F is eligible for function merging.
ArrayRef< T > makeArrayRef(const T &OneElt)
Construct an ArrayRef from a single element.
Definition: ArrayRef.h:451
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:743
This file contains the simple types necessary to represent the attributes associated with functions a...
Value * CreateIntToPtr(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1727
bool hasExternalLinkage() const
Definition: GlobalValue.h:422
Subprogram description.
Class to represent function types.
Definition: DerivedTypes.h:103
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1732
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
Value handle that is nullable, but tries to track the Value.
Definition: ValueHandle.h:182
AttributeList getAttributes() const
Return the attribute list for this Function.
Definition: Function.h:224
An instruction for storing to memory.
Definition: Instructions.h:321
LinkageTypes getLinkage() const
Definition: GlobalValue.h:451
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
bool hasLinkOnceLinkage() const
Definition: GlobalValue.h:426
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:291
iterator begin()
Definition: Function.h:656
void initializeMergeFunctionsPass(PassRegistry &)
static bool canCreateAliasFor(Function *F)
void erase(GlobalValue *Global)
Class to represent pointers.
Definition: DerivedTypes.h:467
static cl::opt< unsigned > NumFunctionsForSanityCheck("mergefunc-sanity", cl::desc("How many functions in module could be used for " "MergeFunctions pass sanity check. " "'0' disables this check. Works only with '-debug' key."), cl::init(0), cl::Hidden)
static FunctionHash functionHash(Function &)
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1773
bool isVoidTy() const
Return true if this is &#39;void&#39;.
Definition: Type.h:141
const BasicBlock & getEntryBlock() const
Definition: Function.h:640
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:423
Type * getReturnType() const
Returns the type of the ret val.
Definition: Function.h:169
static Function * Create(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace, const Twine &N="", Module *M=nullptr)
Definition: Function.h:136
FunctionComparator - Compares two functions to determine whether or not they will generate machine co...
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:308
VisibilityTypes getVisibility() const
Definition: GlobalValue.h:233
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
DISubprogram * getSubprogram() const
Get the attached subprogram.
Definition: Metadata.cpp:1508
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:42
void copyAttributesFrom(const Function *Src)
copyAttributesFrom - copy all additional attributes (those not needed to create a Function) from the ...
Definition: Function.cpp:484
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:224
#define H(x, y, z)
Definition: MD5.cpp:57
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:371
size_t size() const
Definition: BasicBlock.h:279
const Instruction & back() const
Definition: BasicBlock.h:283
unsigned getAddressSpace() const
Definition: Globals.cpp:111
void print(raw_ostream &O, bool IsForDebug=false) const
Implement operator<< on Value.
Definition: AsmWriter.cpp:4148
void setCallingConv(CallingConv::ID CC)
Definition: InstrTypes.h:1229
static bool isDiscardableIfUnused(LinkageTypes Linkage)
Whether the definition of this global may be discarded if it is not used in its compilation unit...
Definition: GlobalValue.h:361
unsigned getStructNumElements() const
Definition: DerivedTypes.h:329
static BasicBlock * Create(LLVMContext &Context, const Twine &Name="", Function *Parent=nullptr, BasicBlock *InsertBefore=nullptr)
Creates a new BasicBlock.
Definition: BasicBlock.h:100
LLVMContext & getContext() const
getContext - Return a reference to the LLVMContext associated with this function. ...
Definition: Function.cpp:193
void setTailCall(bool isTC=true)
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1415
Value * CreateExtractValue(Value *Agg, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:2083
unsigned first
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:34
bool hasWeakLinkage() const
Definition: GlobalValue.h:430
void print(raw_ostream &OS, const Module *M=nullptr, bool IsForDebug=false) const
Print.
Definition: AsmWriter.cpp:4277
static cl::opt< bool > MergeFunctionsPDI("mergefunc-preserve-debug-info", cl::Hidden, cl::init(false), cl::desc("Preserve debug info in thunk when mergefunc " "transformations are made."))
Iterator for intrusive lists based on ilist_node.
static bool canCreateThunkFor(Function *F)
Whether this function may be replaced by a forwarding thunk.
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:418
iterator end()
Definition: BasicBlock.h:271
CallingConv::ID getCallingConv() const
getCallingConv()/setCallingConv(CC) - These method get and set the calling convention of this functio...
Definition: Function.h:213
GlobalNumberState assigns an integer to each global value in the program, which is used by the compar...
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:847
Module.h This file contains the declarations for the Module class.
const DataFlowGraph & G
Definition: RDFGraph.cpp:211
bool hasGlobalUnnamedAddr() const
Definition: GlobalValue.h:200
Value handle that asserts if the Value is deleted.
Definition: ValueHandle.h:238
void setLinkage(LinkageTypes LT)
Definition: GlobalValue.h:445
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
FunctionType * getFunctionType() const
Returns the FunctionType for me.
Definition: Function.h:164
int compare()
Test whether the two functions have equivalent behaviour.
iterator_range< user_iterator > users()
Definition: Value.h:400
static cl::opt< bool > MergeFunctionsAliases("mergefunc-use-aliases", cl::Hidden, cl::init(false), cl::desc("Allow mergefunc to create aliases"))
amdgpu Simplify well known AMD library false Value Value * Arg
use_iterator use_begin()
Definition: Value.h:339
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
SymbolTableList< BasicBlock >::iterator eraseFromParent()
Unlink &#39;this&#39; from the containing function and delete it.
Definition: BasicBlock.cpp:115
#define I(x, y, z)
Definition: MD5.cpp:58
ModulePass class - This class is used to implement unstructured interprocedural optimizations and ana...
Definition: Pass.h:225
void setAttributes(AttributeList A)
Set the parameter attributes for this call.
Definition: InstrTypes.h:1248
void eraseFromParent()
eraseFromParent - This method unlinks &#39;this&#39; from the containing module and deletes it...
Definition: Function.cpp:214
Value * CreatePtrToInt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1722
bool isDeclaration() const
Return true if the primary definition of this global value is outside of the current translation unit...
Definition: Globals.cpp:206
int compare(DigitsT LDigits, int16_t LScale, DigitsT RDigits, int16_t RScale)
Compare two scaled numbers.
Definition: ScaledNumber.h:252
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
const BasicBlock & front() const
Definition: Function.h:663
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:566
LLVM Value Representation.
Definition: Value.h:73
Value * CreateInsertValue(Value *Agg, Value *Val, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:2091
void pop_back()
Definition: ilist.h:318
#define LLVM_DEBUG(X)
Definition: Debug.h:123
bool use_empty() const
Definition: Value.h:323
static GlobalAlias * create(Type *Ty, unsigned AddressSpace, LinkageTypes Linkage, const Twine &Name, Constant *Aliasee, Module *Parent)
If a parent module is specified, the alias is automatically inserted into the end of the specified mo...
Definition: Globals.cpp:423
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
PointerType * getType() const
Global values are always pointers.
Definition: GlobalValue.h:274
static AttributeList get(LLVMContext &C, ArrayRef< std::pair< unsigned, Attribute >> Attrs)
Create an AttributeList with the specified parameters in it.
Definition: Attributes.cpp:873
iterator_range< arg_iterator > args()
Definition: Function.h:689
bool isStructTy() const
True if this is an instance of StructType.
Definition: Type.h:218
an instruction to allocate memory on the stack
Definition: Instructions.h:60