LLVM  3.7.0
ObjCARCContract.cpp
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1 //===- ObjCARCContract.cpp - ObjC ARC Optimization ------------------------===//
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 /// \file
10 /// This file defines late ObjC ARC optimizations. ARC stands for Automatic
11 /// Reference Counting and is a system for managing reference counts for objects
12 /// in Objective C.
13 ///
14 /// This specific file mainly deals with ``contracting'' multiple lower level
15 /// operations into singular higher level operations through pattern matching.
16 ///
17 /// WARNING: This file knows about certain library functions. It recognizes them
18 /// by name, and hardwires knowledge of their semantics.
19 ///
20 /// WARNING: This file knows about how certain Objective-C library functions are
21 /// used. Naive LLVM IR transformations which would otherwise be
22 /// behavior-preserving may break these assumptions.
23 ///
24 //===----------------------------------------------------------------------===//
25 
26 // TODO: ObjCARCContract could insert PHI nodes when uses aren't
27 // dominated by single calls.
28 
29 #include "ObjCARC.h"
30 #include "ARCRuntimeEntryPoints.h"
31 #include "DependencyAnalysis.h"
32 #include "ProvenanceAnalysis.h"
33 #include "llvm/ADT/Statistic.h"
34 #include "llvm/IR/Dominators.h"
35 #include "llvm/IR/InlineAsm.h"
36 #include "llvm/IR/Operator.h"
37 #include "llvm/Support/Debug.h"
39 
40 using namespace llvm;
41 using namespace llvm::objcarc;
42 
43 #define DEBUG_TYPE "objc-arc-contract"
44 
45 STATISTIC(NumPeeps, "Number of calls peephole-optimized");
46 STATISTIC(NumStoreStrongs, "Number objc_storeStrong calls formed");
47 
48 //===----------------------------------------------------------------------===//
49 // Declarations
50 //===----------------------------------------------------------------------===//
51 
52 namespace {
53  /// \brief Late ARC optimizations
54  ///
55  /// These change the IR in a way that makes it difficult to be analyzed by
56  /// ObjCARCOpt, so it's run late.
57  class ObjCARCContract : public FunctionPass {
58  bool Changed;
59  AliasAnalysis *AA;
60  DominatorTree *DT;
63 
64  /// A flag indicating whether this optimization pass should run.
65  bool Run;
66 
67  /// The inline asm string to insert between calls and RetainRV calls to make
68  /// the optimization work on targets which need it.
69  const MDString *RetainRVMarker;
70 
71  /// The set of inserted objc_storeStrong calls. If at the end of walking the
72  /// function we have found no alloca instructions, these calls can be marked
73  /// "tail".
74  SmallPtrSet<CallInst *, 8> StoreStrongCalls;
75 
76  /// Returns true if we eliminated Inst.
77  bool tryToPeepholeInstruction(Function &F, Instruction *Inst,
78  inst_iterator &Iter,
81  bool &TailOkForStoreStrong);
82 
83  bool optimizeRetainCall(Function &F, Instruction *Retain);
84 
85  bool
86  contractAutorelease(Function &F, Instruction *Autorelease,
87  ARCInstKind Class,
88  SmallPtrSetImpl<Instruction *> &DependingInstructions,
90 
91  void tryToContractReleaseIntoStoreStrong(Instruction *Release,
92  inst_iterator &Iter);
93 
94  void getAnalysisUsage(AnalysisUsage &AU) const override;
95  bool doInitialization(Module &M) override;
96  bool runOnFunction(Function &F) override;
97 
98  public:
99  static char ID;
100  ObjCARCContract() : FunctionPass(ID) {
102  }
103  };
104 }
105 
106 //===----------------------------------------------------------------------===//
107 // Implementation
108 //===----------------------------------------------------------------------===//
109 
110 /// Turn objc_retain into objc_retainAutoreleasedReturnValue if the operand is a
111 /// return value. We do this late so we do not disrupt the dataflow analysis in
112 /// ObjCARCOpt.
113 bool ObjCARCContract::optimizeRetainCall(Function &F, Instruction *Retain) {
115  const Instruction *Call = CS.getInstruction();
116  if (!Call)
117  return false;
118  if (Call->getParent() != Retain->getParent())
119  return false;
120 
121  // Check that the call is next to the retain.
123  ++I;
124  while (IsNoopInstruction(I)) ++I;
125  if (&*I != Retain)
126  return false;
127 
128  // Turn it to an objc_retainAutoreleasedReturnValue.
129  Changed = true;
130  ++NumPeeps;
131 
132  DEBUG(dbgs() << "Transforming objc_retain => "
133  "objc_retainAutoreleasedReturnValue since the operand is a "
134  "return value.\nOld: "<< *Retain << "\n");
135 
136  // We do not have to worry about tail calls/does not throw since
137  // retain/retainRV have the same properties.
139  cast<CallInst>(Retain)->setCalledFunction(Decl);
140 
141  DEBUG(dbgs() << "New: " << *Retain << "\n");
142  return true;
143 }
144 
145 /// Merge an autorelease with a retain into a fused call.
146 bool ObjCARCContract::contractAutorelease(
147  Function &F, Instruction *Autorelease, ARCInstKind Class,
148  SmallPtrSetImpl<Instruction *> &DependingInstructions,
150  const Value *Arg = GetArgRCIdentityRoot(Autorelease);
151 
152  // Check that there are no instructions between the retain and the autorelease
153  // (such as an autorelease_pop) which may change the count.
154  CallInst *Retain = nullptr;
155  if (Class == ARCInstKind::AutoreleaseRV)
157  Autorelease->getParent(), Autorelease,
158  DependingInstructions, Visited, PA);
159  else
161  Autorelease->getParent(), Autorelease,
162  DependingInstructions, Visited, PA);
163 
164  Visited.clear();
165  if (DependingInstructions.size() != 1) {
166  DependingInstructions.clear();
167  return false;
168  }
169 
170  Retain = dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
171  DependingInstructions.clear();
172 
173  if (!Retain || GetBasicARCInstKind(Retain) != ARCInstKind::Retain ||
174  GetArgRCIdentityRoot(Retain) != Arg)
175  return false;
176 
177  Changed = true;
178  ++NumPeeps;
179 
180  DEBUG(dbgs() << " Fusing retain/autorelease!\n"
181  " Autorelease:" << *Autorelease << "\n"
182  " Retain: " << *Retain << "\n");
183 
184  Constant *Decl = EP.get(Class == ARCInstKind::AutoreleaseRV
187  Retain->setCalledFunction(Decl);
188 
189  DEBUG(dbgs() << " New RetainAutorelease: " << *Retain << "\n");
190 
191  EraseInstruction(Autorelease);
192  return true;
193 }
194 
196  Instruction *Release,
197  ProvenanceAnalysis &PA,
198  AliasAnalysis *AA) {
199  StoreInst *Store = nullptr;
200  bool SawRelease = false;
201 
202  // Get the location associated with Load.
204 
205  // Walk down to find the store and the release, which may be in either order.
206  for (auto I = std::next(BasicBlock::iterator(Load)),
207  E = Load->getParent()->end();
208  I != E; ++I) {
209  // If we found the store we were looking for and saw the release,
210  // break. There is no more work to be done.
211  if (Store && SawRelease)
212  break;
213 
214  // Now we know that we have not seen either the store or the release. If I
215  // is the release, mark that we saw the release and continue.
216  Instruction *Inst = &*I;
217  if (Inst == Release) {
218  SawRelease = true;
219  continue;
220  }
221 
222  // Otherwise, we check if Inst is a "good" store. Grab the instruction class
223  // of Inst.
224  ARCInstKind Class = GetBasicARCInstKind(Inst);
225 
226  // If Inst is an unrelated retain, we don't care about it.
227  //
228  // TODO: This is one area where the optimization could be made more
229  // aggressive.
230  if (IsRetain(Class))
231  continue;
232 
233  // If we have seen the store, but not the release...
234  if (Store) {
235  // We need to make sure that it is safe to move the release from its
236  // current position to the store. This implies proving that any
237  // instruction in between Store and the Release conservatively can not use
238  // the RCIdentityRoot of Release. If we can prove we can ignore Inst, so
239  // continue...
240  if (!CanUse(Inst, Load, PA, Class)) {
241  continue;
242  }
243 
244  // Otherwise, be conservative and return nullptr.
245  return nullptr;
246  }
247 
248  // Ok, now we know we have not seen a store yet. See if Inst can write to
249  // our load location, if it can not, just ignore the instruction.
250  if (!(AA->getModRefInfo(Inst, Loc) & AliasAnalysis::Mod))
251  continue;
252 
253  Store = dyn_cast<StoreInst>(Inst);
254 
255  // If Inst can, then check if Inst is a simple store. If Inst is not a
256  // store or a store that is not simple, then we have some we do not
257  // understand writing to this memory implying we can not move the load
258  // over the write to any subsequent store that we may find.
259  if (!Store || !Store->isSimple())
260  return nullptr;
261 
262  // Then make sure that the pointer we are storing to is Ptr. If so, we
263  // found our Store!
264  if (Store->getPointerOperand() == Loc.Ptr)
265  continue;
266 
267  // Otherwise, we have an unknown store to some other ptr that clobbers
268  // Loc.Ptr. Bail!
269  return nullptr;
270  }
271 
272  // If we did not find the store or did not see the release, fail.
273  if (!Store || !SawRelease)
274  return nullptr;
275 
276  // We succeeded!
277  return Store;
278 }
279 
280 static Instruction *
282  Instruction *Release,
283  ProvenanceAnalysis &PA) {
284  // Walk up from the Store to find the retain.
286  BasicBlock::iterator Begin = Store->getParent()->begin();
287  while (I != Begin && GetBasicARCInstKind(I) != ARCInstKind::Retain) {
288  Instruction *Inst = &*I;
289 
290  // It is only safe to move the retain to the store if we can prove
291  // conservatively that nothing besides the release can decrement reference
292  // counts in between the retain and the store.
293  if (CanDecrementRefCount(Inst, New, PA) && Inst != Release)
294  return nullptr;
295  --I;
296  }
297  Instruction *Retain = I;
299  return nullptr;
300  if (GetArgRCIdentityRoot(Retain) != New)
301  return nullptr;
302  return Retain;
303 }
304 
305 /// Attempt to merge an objc_release with a store, load, and objc_retain to form
306 /// an objc_storeStrong. An objc_storeStrong:
307 ///
308 /// objc_storeStrong(i8** %old_ptr, i8* new_value)
309 ///
310 /// is equivalent to the following IR sequence:
311 ///
312 /// ; Load old value.
313 /// %old_value = load i8** %old_ptr (1)
314 ///
315 /// ; Increment the new value and then release the old value. This must occur
316 /// ; in order in case old_value releases new_value in its destructor causing
317 /// ; us to potentially have a dangling ptr.
318 /// tail call i8* @objc_retain(i8* %new_value) (2)
319 /// tail call void @objc_release(i8* %old_value) (3)
320 ///
321 /// ; Store the new_value into old_ptr
322 /// store i8* %new_value, i8** %old_ptr (4)
323 ///
324 /// The safety of this optimization is based around the following
325 /// considerations:
326 ///
327 /// 1. We are forming the store strong at the store. Thus to perform this
328 /// optimization it must be safe to move the retain, load, and release to
329 /// (4).
330 /// 2. We need to make sure that any re-orderings of (1), (2), (3), (4) are
331 /// safe.
332 void ObjCARCContract::tryToContractReleaseIntoStoreStrong(Instruction *Release,
333  inst_iterator &Iter) {
334  // See if we are releasing something that we just loaded.
335  auto *Load = dyn_cast<LoadInst>(GetArgRCIdentityRoot(Release));
336  if (!Load || !Load->isSimple())
337  return;
338 
339  // For now, require everything to be in one basic block.
340  BasicBlock *BB = Release->getParent();
341  if (Load->getParent() != BB)
342  return;
343 
344  // First scan down the BB from Load, looking for a store of the RCIdentityRoot
345  // of Load's
346  StoreInst *Store =
348  // If we fail, bail.
349  if (!Store)
350  return;
351 
352  // Then find what new_value's RCIdentity Root is.
353  Value *New = GetRCIdentityRoot(Store->getValueOperand());
354 
355  // Then walk up the BB and look for a retain on New without any intervening
356  // instructions which conservatively might decrement ref counts.
357  Instruction *Retain =
358  findRetainForStoreStrongContraction(New, Store, Release, PA);
359 
360  // If we fail, bail.
361  if (!Retain)
362  return;
363 
364  Changed = true;
365  ++NumStoreStrongs;
366 
367  DEBUG(
368  llvm::dbgs() << " Contracting retain, release into objc_storeStrong.\n"
369  << " Old:\n"
370  << " Store: " << *Store << "\n"
371  << " Release: " << *Release << "\n"
372  << " Retain: " << *Retain << "\n"
373  << " Load: " << *Load << "\n");
374 
375  LLVMContext &C = Release->getContext();
377  Type *I8XX = PointerType::getUnqual(I8X);
378 
379  Value *Args[] = { Load->getPointerOperand(), New };
380  if (Args[0]->getType() != I8XX)
381  Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
382  if (Args[1]->getType() != I8X)
383  Args[1] = new BitCastInst(Args[1], I8X, "", Store);
385  CallInst *StoreStrong = CallInst::Create(Decl, Args, "", Store);
386  StoreStrong->setDoesNotThrow();
387  StoreStrong->setDebugLoc(Store->getDebugLoc());
388 
389  // We can't set the tail flag yet, because we haven't yet determined
390  // whether there are any escaping allocas. Remember this call, so that
391  // we can set the tail flag once we know it's safe.
392  StoreStrongCalls.insert(StoreStrong);
393 
394  DEBUG(llvm::dbgs() << " New Store Strong: " << *StoreStrong << "\n");
395 
396  if (&*Iter == Store) ++Iter;
397  Store->eraseFromParent();
398  Release->eraseFromParent();
399  EraseInstruction(Retain);
400  if (Load->use_empty())
401  Load->eraseFromParent();
402 }
403 
404 bool ObjCARCContract::tryToPeepholeInstruction(
405  Function &F, Instruction *Inst, inst_iterator &Iter,
406  SmallPtrSetImpl<Instruction *> &DependingInsts,
408  bool &TailOkForStoreStrongs) {
409  // Only these library routines return their argument. In particular,
410  // objc_retainBlock does not necessarily return its argument.
411  ARCInstKind Class = GetBasicARCInstKind(Inst);
412  switch (Class) {
415  return false;
418  return contractAutorelease(F, Inst, Class, DependingInsts, Visited);
419  case ARCInstKind::Retain:
420  // Attempt to convert retains to retainrvs if they are next to function
421  // calls.
422  if (!optimizeRetainCall(F, Inst))
423  return false;
424  // If we succeed in our optimization, fall through.
425  // FALLTHROUGH
426  case ARCInstKind::RetainRV: {
427  // If we're compiling for a target which needs a special inline-asm
428  // marker to do the retainAutoreleasedReturnValue optimization,
429  // insert it now.
430  if (!RetainRVMarker)
431  return false;
432  BasicBlock::iterator BBI = Inst;
433  BasicBlock *InstParent = Inst->getParent();
434 
435  // Step up to see if the call immediately precedes the RetainRV call.
436  // If it's an invoke, we have to cross a block boundary. And we have
437  // to carefully dodge no-op instructions.
438  do {
439  if (&*BBI == InstParent->begin()) {
440  BasicBlock *Pred = InstParent->getSinglePredecessor();
441  if (!Pred)
442  goto decline_rv_optimization;
443  BBI = Pred->getTerminator();
444  break;
445  }
446  --BBI;
447  } while (IsNoopInstruction(BBI));
448 
449  if (&*BBI == GetArgRCIdentityRoot(Inst)) {
450  DEBUG(dbgs() << "Adding inline asm marker for "
451  "retainAutoreleasedReturnValue optimization.\n");
452  Changed = true;
453  InlineAsm *IA =
455  /*isVarArg=*/false),
456  RetainRVMarker->getString(),
457  /*Constraints=*/"", /*hasSideEffects=*/true);
458  CallInst::Create(IA, "", Inst);
459  }
460  decline_rv_optimization:
461  return false;
462  }
463  case ARCInstKind::InitWeak: {
464  // objc_initWeak(p, null) => *p = null
465  CallInst *CI = cast<CallInst>(Inst);
466  if (IsNullOrUndef(CI->getArgOperand(1))) {
467  Value *Null =
468  ConstantPointerNull::get(cast<PointerType>(CI->getType()));
469  Changed = true;
470  new StoreInst(Null, CI->getArgOperand(0), CI);
471 
472  DEBUG(dbgs() << "OBJCARCContract: Old = " << *CI << "\n"
473  << " New = " << *Null << "\n");
474 
475  CI->replaceAllUsesWith(Null);
476  CI->eraseFromParent();
477  }
478  return true;
479  }
481  // Try to form an objc store strong from our release. If we fail, there is
482  // nothing further to do below, so continue.
483  tryToContractReleaseIntoStoreStrong(Inst, Iter);
484  return true;
485  case ARCInstKind::User:
486  // Be conservative if the function has any alloca instructions.
487  // Technically we only care about escaping alloca instructions,
488  // but this is sufficient to handle some interesting cases.
489  if (isa<AllocaInst>(Inst))
490  TailOkForStoreStrongs = false;
491  return true;
493  // Remove calls to @clang.arc.use(...).
494  Inst->eraseFromParent();
495  return true;
496  default:
497  return true;
498  }
499 }
500 
501 //===----------------------------------------------------------------------===//
502 // Top Level Driver
503 //===----------------------------------------------------------------------===//
504 
505 bool ObjCARCContract::runOnFunction(Function &F) {
506  if (!EnableARCOpts)
507  return false;
508 
509  // If nothing in the Module uses ARC, don't do anything.
510  if (!Run)
511  return false;
512 
513  Changed = false;
514  AA = &getAnalysis<AliasAnalysis>();
515  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
516 
517  PA.setAA(&getAnalysis<AliasAnalysis>());
518 
519  DEBUG(llvm::dbgs() << "**** ObjCARC Contract ****\n");
520 
521  // Track whether it's ok to mark objc_storeStrong calls with the "tail"
522  // keyword. Be conservative if the function has variadic arguments.
523  // It seems that functions which "return twice" are also unsafe for the
524  // "tail" argument, because they are setjmp, which could need to
525  // return to an earlier stack state.
526  bool TailOkForStoreStrongs =
528 
529  // For ObjC library calls which return their argument, replace uses of the
530  // argument with uses of the call return value, if it dominates the use. This
531  // reduces register pressure.
532  SmallPtrSet<Instruction *, 4> DependingInstructions;
534  for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E;) {
535  Instruction *Inst = &*I++;
536 
537  DEBUG(dbgs() << "Visiting: " << *Inst << "\n");
538 
539  // First try to peephole Inst. If there is nothing further we can do in
540  // terms of undoing objc-arc-expand, process the next inst.
541  if (tryToPeepholeInstruction(F, Inst, I, DependingInstructions, Visited,
542  TailOkForStoreStrongs))
543  continue;
544 
545  // Otherwise, try to undo objc-arc-expand.
546 
547  // Don't use GetArgRCIdentityRoot because we don't want to look through bitcasts
548  // and such; to do the replacement, the argument must have type i8*.
549  Value *Arg = cast<CallInst>(Inst)->getArgOperand(0);
550 
551  // TODO: Change this to a do-while.
552  for (;;) {
553  // If we're compiling bugpointed code, don't get in trouble.
554  if (!isa<Instruction>(Arg) && !isa<Argument>(Arg))
555  break;
556  // Look through the uses of the pointer.
557  for (Value::use_iterator UI = Arg->use_begin(), UE = Arg->use_end();
558  UI != UE; ) {
559  // Increment UI now, because we may unlink its element.
560  Use &U = *UI++;
561  unsigned OperandNo = U.getOperandNo();
562 
563  // If the call's return value dominates a use of the call's argument
564  // value, rewrite the use to use the return value. We check for
565  // reachability here because an unreachable call is considered to
566  // trivially dominate itself, which would lead us to rewriting its
567  // argument in terms of its return value, which would lead to
568  // infinite loops in GetArgRCIdentityRoot.
569  if (DT->isReachableFromEntry(U) && DT->dominates(Inst, U)) {
570  Changed = true;
571  Instruction *Replacement = Inst;
572  Type *UseTy = U.get()->getType();
573  if (PHINode *PHI = dyn_cast<PHINode>(U.getUser())) {
574  // For PHI nodes, insert the bitcast in the predecessor block.
575  unsigned ValNo = PHINode::getIncomingValueNumForOperand(OperandNo);
576  BasicBlock *BB = PHI->getIncomingBlock(ValNo);
577  if (Replacement->getType() != UseTy)
578  Replacement = new BitCastInst(Replacement, UseTy, "",
579  &BB->back());
580  // While we're here, rewrite all edges for this PHI, rather
581  // than just one use at a time, to minimize the number of
582  // bitcasts we emit.
583  for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i)
584  if (PHI->getIncomingBlock(i) == BB) {
585  // Keep the UI iterator valid.
586  if (UI != UE &&
587  &PHI->getOperandUse(
589  ++UI;
590  PHI->setIncomingValue(i, Replacement);
591  }
592  } else {
593  if (Replacement->getType() != UseTy)
594  Replacement = new BitCastInst(Replacement, UseTy, "",
595  cast<Instruction>(U.getUser()));
596  U.set(Replacement);
597  }
598  }
599  }
600 
601  // If Arg is a no-op casted pointer, strip one level of casts and iterate.
602  if (const BitCastInst *BI = dyn_cast<BitCastInst>(Arg))
603  Arg = BI->getOperand(0);
604  else if (isa<GEPOperator>(Arg) &&
605  cast<GEPOperator>(Arg)->hasAllZeroIndices())
606  Arg = cast<GEPOperator>(Arg)->getPointerOperand();
607  else if (isa<GlobalAlias>(Arg) &&
608  !cast<GlobalAlias>(Arg)->mayBeOverridden())
609  Arg = cast<GlobalAlias>(Arg)->getAliasee();
610  else
611  break;
612  }
613  }
614 
615  // If this function has no escaping allocas or suspicious vararg usage,
616  // objc_storeStrong calls can be marked with the "tail" keyword.
617  if (TailOkForStoreStrongs)
618  for (CallInst *CI : StoreStrongCalls)
619  CI->setTailCall();
620  StoreStrongCalls.clear();
621 
622  return Changed;
623 }
624 
625 //===----------------------------------------------------------------------===//
626 // Misc Pass Manager
627 //===----------------------------------------------------------------------===//
628 
629 char ObjCARCContract::ID = 0;
630 INITIALIZE_PASS_BEGIN(ObjCARCContract, "objc-arc-contract",
631  "ObjC ARC contraction", false, false)
634 INITIALIZE_PASS_END(ObjCARCContract, "objc-arc-contract",
635  "ObjC ARC contraction", false, false)
636 
637 void ObjCARCContract::getAnalysisUsage(AnalysisUsage &AU) const {
638  AU.addRequired<AliasAnalysis>();
639  AU.addRequired<DominatorTreeWrapperPass>();
640  AU.setPreservesCFG();
641 }
642 
643 Pass *llvm::createObjCARCContractPass() { return new ObjCARCContract(); }
644 
645 bool ObjCARCContract::doInitialization(Module &M) {
646  // If nothing in the Module uses ARC, don't do anything.
647  Run = ModuleHasARC(M);
648  if (!Run)
649  return false;
650 
651  EP.init(&M);
652 
653  // Initialize RetainRVMarker.
654  RetainRVMarker = nullptr;
655  if (NamedMDNode *NMD =
656  M.getNamedMetadata("clang.arc.retainAutoreleasedReturnValueMarker"))
657  if (NMD->getNumOperands() == 1) {
658  const MDNode *N = NMD->getOperand(0);
659  if (N->getNumOperands() == 1)
660  if (const MDString *S = dyn_cast<MDString>(N->getOperand(0)))
661  RetainRVMarker = S;
662  }
663 
664  return false;
665 }
Pass interface - Implemented by all 'passes'.
Definition: Pass.h:82
objc arc contract
Value * getValueOperand()
Definition: Instructions.h:406
iplist< Instruction >::iterator eraseFromParent()
eraseFromParent - This method unlinks 'this' from the containing basic block and deletes it...
Definition: Instruction.cpp:70
use_iterator use_end()
Definition: Value.h:281
use_iterator_impl< Use > use_iterator
Definition: Value.h:277
This file declares special dependency analysis routines used in Objective C ARC Optimizations.
void setDoesNotThrow()
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
const Instruction & back() const
Definition: BasicBlock.h:245
objc arc ObjC ARC false
This file contains a class ARCRuntimeEntryPoints for use in creating/managing references to entry poi...
STATISTIC(NumFunctions,"Total number of functions")
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:114
bool CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA, ARCInstKind Class)
Test whether the given instruction can "use" the given pointer's object in a way that requires the ...
Blocks objc_retainAutorelease.
unsigned getNumOperands() const
Return number of MDNode operands.
Definition: Metadata.h:942
bool isSimple() const
Definition: Instructions.h:401
CallInst - This class represents a function call, abstracting a target machine's calling convention...
static ARCInstKind GetBasicARCInstKind(const Value *V)
Determine which objc runtime call instruction class V belongs to.
Definition: ARCInstKind.h:101
Metadata node.
Definition: Metadata.h:740
F(f)
LoadInst - an instruction for reading from memory.
Definition: Instructions.h:177
FunctionType * getType(LLVMContext &Context, ID id, ArrayRef< Type * > Tys=None)
Return the function type for an intrinsic.
Definition: Function.cpp:822
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:242
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:231
static unsigned getOperandNumForIncomingValue(unsigned i)
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:70
A tuple of MDNodes.
Definition: Metadata.h:1127
objc_autoreleaseReturnValue
static Value * getPointerOperand(Instruction &Inst)
inst_iterator inst_begin(Function *F)
Definition: InstIterator.h:127
static CallInst * Create(Value *Func, ArrayRef< Value * > Args, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
A Use represents the edge between a Value definition and its users.
Definition: Use.h:69
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:75
void initializeObjCARCContractPass(PassRegistry &)
This file defines common definitions/declarations used by the ObjC ARC Optimizer. ...
INITIALIZE_PASS_BEGIN(ObjCARCContract,"objc-arc-contract","ObjC ARC contraction", false, false) INITIALIZE_PASS_END(ObjCARCContract
objc_retainAutoreleasedReturnValue
Pass * createObjCARCContractPass()
bool EnableARCOpts
A handy option to enable/disable all ARC Optimizations.
Definition: ObjCARC.cpp:30
This class represents a no-op cast from one type to another.
static FunctionType * get(Type *Result, ArrayRef< Type * > Params, bool isVarArg)
FunctionType::get - This static method is the primary way of constructing a FunctionType.
Definition: Type.cpp:361
StoreInst - an instruction for storing to memory.
Definition: Instructions.h:316
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:351
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:67
static MemoryLocation get(const LoadInst *LI)
Return a location with information about the memory reference by the given instruction.
static StoreInst * findSafeStoreForStoreStrongContraction(LoadInst *Load, Instruction *Release, ProvenanceAnalysis &PA, AliasAnalysis *AA)
void setDebugLoc(DebugLoc Loc)
setDebugLoc - Set the debug location information for this instruction.
Definition: Instruction.h:227
static ConstantPointerNull * get(PointerType *T)
get() - Static factory methods - Return objects of the specified value
Definition: Constants.cpp:1455
void set(Value *Val)
Definition: Value.h:516
unsigned getOperandNo() const
Return the operand # of this use in its User.
Definition: Use.cpp:48
LLVM Basic Block Representation.
Definition: BasicBlock.h:65
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
This is an important class for using LLVM in a threaded context.
Definition: LLVMContext.h:41
This is an important base class in LLVM.
Definition: Constant.h:41
objc_initWeak (derived)
const DebugLoc & getDebugLoc() const
getDebugLoc - Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:230
Represent the analysis usage information of a pass.
static Type * getVoidTy(LLVMContext &C)
Definition: Type.cpp:225
Value * get() const
Definition: Use.h:95
User * getUser() const
Returns the User that contains this Use.
Definition: Use.cpp:41
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:294
static bool IsNoopInstruction(const Instruction *I)
static Instruction * findRetainForStoreStrongContraction(Value *New, StoreInst *Store, Instruction *Release, ProvenanceAnalysis &PA)
#define INITIALIZE_AG_DEPENDENCY(depName)
Definition: PassSupport.h:72
void setTailCall(bool isTC=true)
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:519
static unsigned getIncomingValueNumForOperand(unsigned i)
bool CanDecrementRefCount(ARCInstKind Kind)
Returns false if conservatively we can prove that any instruction mapped to this kind can not decreme...
const Value * Ptr
The address of the start of the location.
Representation for a specific memory location.
static Value * GetArgRCIdentityRoot(Value *Inst)
Assuming the given instruction is one of the special calls such as objc_retain or objc_release...
static void EraseInstruction(Instruction *CI)
Erase the given instruction.
objc arc ObjC ARC contraction
const MDOperand & getOperand(unsigned I) const
Definition: Metadata.h:936
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:299
static PointerType * getUnqual(Type *ElementType)
PointerType::getUnqual - This constructs a pointer to an object of the specified type in the generic ...
Definition: DerivedTypes.h:460
iterator end()
Definition: BasicBlock.h:233
static bool IsNullOrUndef(const Value *V)
This file declares a special form of Alias Analysis called ``Provenance Analysis''.
ARCInstKind
Equivalence classes of instructions in the ARC Model.
Definition: ARCInstKind.h:30
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:222
ModRefResult getModRefInfo(const Instruction *I)
getModRefInfo - Return information about whether or not an instruction may read or write memory (with...
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
Value * getArgOperand(unsigned i) const
getArgOperand/setArgOperand - Return/set the i-th call argument.
BasicBlock * getSinglePredecessor()
Return the predecessor of this block if it has a single predecessor block.
Definition: BasicBlock.cpp:211
objc arc
LLVM_ATTRIBUTE_UNUSED_RESULT std::enable_if< !is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:285
objc_storeStrong (derived)
could "use" a pointer
bool IsRetain(ARCInstKind Class)
Test if the given class is objc_retain or equivalent.
use_iterator use_begin()
Definition: Value.h:279
void setCalledFunction(Value *Fn)
setCalledFunction - Set the function called.
NamedMDNode * getNamedMetadata(const Twine &Name) const
Return the first NamedMDNode in the module with the specified name.
Definition: Module.cpp:253
ImmutableCallSite - establish a view to a call site for examination.
Definition: CallSite.h:418
Blocks objc_retainAutoreleaseReturnValue.
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
TerminatorInst * getTerminator()
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:124
bool callsFunctionThatReturnsTwice() const
callsFunctionThatReturnsTwice - Return true if the function has a call to setjmp or other function th...
Definition: Function.cpp:916
Declarations for ObjC runtime functions and constants.
static InlineAsm * get(FunctionType *Ty, StringRef AsmString, StringRef Constraints, bool hasSideEffects, bool isAlignStack=false, AsmDialect asmDialect=AD_ATT)
InlineAsm::get - Return the specified uniqued inline asm string.
Definition: InlineAsm.cpp:28
static const Value * GetRCIdentityRoot(const Value *V)
The RCIdentity root of a value V is a dominating value U for which retaining or releasing U is equiva...
LLVM Value Representation.
Definition: Value.h:69
#define DEBUG(X)
Definition: Debug.h:92
This is similar to BasicAliasAnalysis, and it uses many of the same techniques, except it uses specia...
C - The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
inst_iterator inst_end(Function *F)
Definition: InstIterator.h:128
A single uniqued string.
Definition: Metadata.h:508
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:203
bool isVarArg() const
isVarArg - Return true if this function takes a variable number of arguments.
Definition: Function.cpp:229
void FindDependencies(DependenceKind Flavor, const Value *Arg, BasicBlock *StartBB, Instruction *StartInst, SmallPtrSetImpl< Instruction * > &DependingInstructions, SmallPtrSetImpl< const BasicBlock * > &Visited, ProvenanceAnalysis &PA)
Walk up the CFG from StartPos (which is in StartBB) and find local and non-local dependencies on Arg...
Value * getPointerOperand()
Definition: Instructions.h:409
static IntegerType * getInt8Ty(LLVMContext &C)
Definition: Type.cpp:237
const BasicBlock * getParent() const
Definition: Instruction.h:72
static bool ModuleHasARC(const Module &M)
Test if the given module looks interesting to run ARC optimization on.