namespace {
/// \brief Unidirectional information about either a
/// retain-decrement-use-release sequence or release-use-decrement-retain
- /// reverese sequence.
+ /// reverse sequence.
struct RRInfo {
/// After an objc_retain, the reference count of the referenced
/// object is known to be positive. Similarly, before an objc_release, the
KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0) {}
void clear();
+
+ bool IsTrackingImpreciseReleases() {
+ return ReleaseMetadata != 0;
+ }
};
}
/// True if the reference count is known to be incremented.
bool KnownPositiveRefCount;
- /// True of we've seen an opportunity for partial RR elimination, such as
+ /// True if we've seen an opportunity for partial RR elimination, such as
/// pushing calls into a CFG triangle or into one side of a CFG diamond.
bool Partial;
void SetSeq(Sequence NewSeq) {
DEBUG(dbgs() << "Old: " << Seq << "; New: " << NewSeq << "\n");
- Seq = NewSeq;
+ Seq = NewSeq;
}
Sequence GetSeq() const {
}
void ResetSequenceProgress(Sequence NewSeq) {
+ DEBUG(dbgs() << "Resetting sequence progress.\n");
SetSeq(NewSeq);
Partial = false;
RRI.clear();
/// Enable/disable ARC sequence annotations.
static cl::opt<bool>
-EnableARCAnnotations("enable-objc-arc-annotations", cl::init(false));
+EnableARCAnnotations("enable-objc-arc-annotations", cl::init(false),
+ cl::desc("Enable emission of arc data flow analysis "
+ "annotations"));
+static cl::opt<bool>
+DisableCheckForCFGHazards("disable-objc-arc-checkforcfghazards", cl::init(false),
+ cl::desc("Disable check for cfg hazards when "
+ "annotating"));
+static cl::opt<std::string>
+ARCAnnotationTargetIdentifier("objc-arc-annotation-target-identifier",
+ cl::init(""),
+ cl::desc("filter out all data flow annotations "
+ "but those that apply to the given "
+ "target llvm identifier."));
/// This function appends a unique ARCAnnotationProvenanceSourceMDKind id to an
/// instruction so that we can track backwards when post processing via the llvm
/// state of a pointer at the entrance to a basic block.
static void GenerateARCBBEntranceAnnotation(const char *Name, BasicBlock *BB,
Value *Ptr, Sequence Seq) {
+ // If we have a target identifier, make sure that we match it before
+ // continuing.
+ if(!ARCAnnotationTargetIdentifier.empty() &&
+ !Ptr->getName().equals(ARCAnnotationTargetIdentifier))
+ return;
+
Module *M = BB->getParent()->getParent();
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
/// of the pointer at the bottom of the basic block.
static void GenerateARCBBTerminatorAnnotation(const char *Name, BasicBlock *BB,
Value *Ptr, Sequence Seq) {
+ // If we have a target identifier, make sure that we match it before emitting
+ // an annotation.
+ if(!ARCAnnotationTargetIdentifier.empty() &&
+ !Ptr->getName().equals(ARCAnnotationTargetIdentifier))
+ return;
+
Module *M = BB->getParent()->getParent();
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
Sequence OldSeq,
Sequence NewSeq) {
if (EnableARCAnnotations) {
+ // If we have a target identifier, make sure that we match it before
+ // emitting an annotation.
+ if(!ARCAnnotationTargetIdentifier.empty() &&
+ !Ptr->getName().equals(ARCAnnotationTargetIdentifier))
+ return;
+
// First generate the source annotation on our pointer. This will return an
// MDString* if Ptr actually comes from an instruction implying we can put
// in a source annotation. If AppendMDNodeToSourcePtr returns 0 (i.e. NULL),
if (!IsRetainBlockOptimizable(Inst))
return false;
+ Changed = true;
+ ++NumPeeps;
+
+ DEBUG(dbgs() << "Strength reduced retainBlock => retain.\n");
+ DEBUG(dbgs() << "Old: " << *Inst << "\n");
CallInst *RetainBlock = cast<CallInst>(Inst);
RetainBlock->setCalledFunction(getRetainCallee(F.getParent()));
// Remove copy_on_escape metadata.
RetainBlock->setMetadata(CopyOnEscapeMDKind, 0);
Class = IC_Retain;
-
+ DEBUG(dbgs() << "New: " << *Inst << "\n");
return true;
}
break;
}
case IC_RetainBlock:
- // If we strength reduce an objc_retainBlock to amn objc_retain, continue
+ // If we strength reduce an objc_retainBlock to an objc_retain, continue
// onto the objc_retain peephole optimizations. Otherwise break.
if (!OptimizeRetainBlockCall(F, Inst, Class))
break;
}
}
+/// If we have a top down pointer in the S_Use state, make sure that there are
+/// no CFG hazards by checking the states of various bottom up pointers.
+static void CheckForUseCFGHazard(const Sequence SuccSSeq,
+ const bool SuccSRRIKnownSafe,
+ PtrState &S,
+ bool &SomeSuccHasSame,
+ bool &AllSuccsHaveSame,
+ bool &ShouldContinue) {
+ switch (SuccSSeq) {
+ case S_CanRelease: {
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
+ S.ClearSequenceProgress();
+ break;
+ }
+ ShouldContinue = true;
+ break;
+ }
+ case S_Use:
+ SomeSuccHasSame = true;
+ break;
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
+ AllSuccsHaveSame = false;
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ case S_None:
+ llvm_unreachable("This should have been handled earlier.");
+ }
+}
+
+/// If we have a Top Down pointer in the S_CanRelease state, make sure that
+/// there are no CFG hazards by checking the states of various bottom up
+/// pointers.
+static void CheckForCanReleaseCFGHazard(const Sequence SuccSSeq,
+ const bool SuccSRRIKnownSafe,
+ PtrState &S,
+ bool &SomeSuccHasSame,
+ bool &AllSuccsHaveSame) {
+ switch (SuccSSeq) {
+ case S_CanRelease:
+ SomeSuccHasSame = true;
+ break;
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ case S_Use:
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
+ AllSuccsHaveSame = false;
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ case S_None:
+ llvm_unreachable("This should have been handled earlier.");
+ }
+}
+
/// Check for critical edges, loop boundaries, irreducible control flow, or
/// other CFG structures where moving code across the edge would result in it
/// being executed more.
// If any top-down local-use or possible-dec has a succ which is earlier in
// the sequence, forget it.
for (BBState::ptr_iterator I = MyStates.top_down_ptr_begin(),
- E = MyStates.top_down_ptr_end(); I != E; ++I)
- switch (I->second.GetSeq()) {
- default: break;
- case S_Use: {
- const Value *Arg = I->first;
- const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
- bool SomeSuccHasSame = false;
- bool AllSuccsHaveSame = true;
- PtrState &S = I->second;
- succ_const_iterator SI(TI), SE(TI, false);
-
- for (; SI != SE; ++SI) {
- Sequence SuccSSeq = S_None;
- bool SuccSRRIKnownSafe = false;
- // If VisitBottomUp has pointer information for this successor, take
- // what we know about it.
- DenseMap<const BasicBlock *, BBState>::iterator BBI =
- BBStates.find(*SI);
- assert(BBI != BBStates.end());
- const PtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
- SuccSSeq = SuccS.GetSeq();
- SuccSRRIKnownSafe = SuccS.RRI.KnownSafe;
- switch (SuccSSeq) {
- case S_None:
- case S_CanRelease: {
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
- S.ClearSequenceProgress();
- break;
- }
- continue;
- }
- case S_Use:
- SomeSuccHasSame = true;
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
- AllSuccsHaveSame = false;
- break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
- }
- }
- // If the state at the other end of any of the successor edges
- // matches the current state, require all edges to match. This
- // guards against loops in the middle of a sequence.
- if (SomeSuccHasSame && !AllSuccsHaveSame)
+ E = MyStates.top_down_ptr_end(); I != E; ++I) {
+ PtrState &S = I->second;
+ const Sequence Seq = I->second.GetSeq();
+
+ // We only care about S_Retain, S_CanRelease, and S_Use.
+ if (Seq == S_None)
+ continue;
+
+ // Make sure that if extra top down states are added in the future that this
+ // code is updated to handle it.
+ assert((Seq == S_Retain || Seq == S_CanRelease || Seq == S_Use) &&
+ "Unknown top down sequence state.");
+
+ const Value *Arg = I->first;
+ const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
+ bool SomeSuccHasSame = false;
+ bool AllSuccsHaveSame = true;
+
+ succ_const_iterator SI(TI), SE(TI, false);
+
+ for (; SI != SE; ++SI) {
+ // If VisitBottomUp has pointer information for this successor, take
+ // what we know about it.
+ const DenseMap<const BasicBlock *, BBState>::iterator BBI =
+ BBStates.find(*SI);
+ assert(BBI != BBStates.end());
+ const PtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
+ const Sequence SuccSSeq = SuccS.GetSeq();
+
+ // If bottom up, the pointer is in an S_None state, clear the sequence
+ // progress since the sequence in the bottom up state finished
+ // suggesting a mismatch in between retains/releases. This is true for
+ // all three cases that we are handling here: S_Retain, S_Use, and
+ // S_CanRelease.
+ if (SuccSSeq == S_None) {
S.ClearSequenceProgress();
- break;
- }
- case S_CanRelease: {
- const Value *Arg = I->first;
- const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
- bool SomeSuccHasSame = false;
- bool AllSuccsHaveSame = true;
- PtrState &S = I->second;
- succ_const_iterator SI(TI), SE(TI, false);
-
- for (; SI != SE; ++SI) {
- Sequence SuccSSeq = S_None;
- bool SuccSRRIKnownSafe = false;
- // If VisitBottomUp has pointer information for this successor, take
- // what we know about it.
- DenseMap<const BasicBlock *, BBState>::iterator BBI =
- BBStates.find(*SI);
- assert(BBI != BBStates.end());
- const PtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
- SuccSSeq = SuccS.GetSeq();
- SuccSRRIKnownSafe = SuccS.RRI.KnownSafe;
- switch (SuccSSeq) {
- case S_None: {
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
- S.ClearSequenceProgress();
- break;
- }
+ continue;
+ }
+
+ // If we have S_Use or S_CanRelease, perform our check for cfg hazard
+ // checks.
+ const bool SuccSRRIKnownSafe = SuccS.RRI.KnownSafe;
+
+ // *NOTE* We do not use Seq from above here since we are allowing for
+ // S.GetSeq() to change while we are visiting basic blocks.
+ switch(S.GetSeq()) {
+ case S_Use: {
+ bool ShouldContinue = false;
+ CheckForUseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S,
+ SomeSuccHasSame, AllSuccsHaveSame,
+ ShouldContinue);
+ if (ShouldContinue)
continue;
- }
- case S_CanRelease:
- SomeSuccHasSame = true;
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- case S_Use:
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
- AllSuccsHaveSame = false;
- break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
- }
+ break;
+ }
+ case S_CanRelease: {
+ CheckForCanReleaseCFGHazard(SuccSSeq, SuccSRRIKnownSafe,
+ S, SomeSuccHasSame,
+ AllSuccsHaveSame);
+ break;
+ }
+ case S_Retain:
+ case S_None:
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ break;
}
- // If the state at the other end of any of the successor edges
- // matches the current state, require all edges to match. This
- // guards against loops in the middle of a sequence.
- if (SomeSuccHasSame && !AllSuccsHaveSame)
- S.ClearSequenceProgress();
- break;
- }
}
+
+ // If the state at the other end of any of the successor edges
+ // matches the current state, require all edges to match. This
+ // guards against loops in the middle of a sequence.
+ if (SomeSuccHasSame && !AllSuccsHaveSame)
+ S.ClearSequenceProgress();
+ }
}
bool
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
+ DEBUG(dbgs() << "Class: " << Class << "\n");
+
switch (Class) {
case IC_Release: {
Arg = GetObjCArg(Inst);
case S_Release:
case S_MovableRelease:
case S_Use:
- S.RRI.ReverseInsertPts.clear();
+ // If OldSeq is not S_Use or OldSeq is S_Use and we are tracking an
+ // imprecise release, clear our reverse insertion points.
+ if (OldSeq != S_Use || S.RRI.IsTrackingImpreciseReleases())
+ S.RRI.ReverseInsertPts.clear();
// FALL THROUGH
case S_CanRelease:
// Don't do retain+release tracking for IC_RetainRV, because it's
llvm_unreachable("bottom-up pointer in retain state!");
}
ANNOTATE_BOTTOMUP(Inst, Arg, OldSeq, S.GetSeq());
- return NestingDetected;
+ // A retain moving bottom up can be a use.
+ break;
}
case IC_AutoreleasepoolPop:
// Conservatively, clear MyStates for all known pointers.
MapVector<Value *, RRInfo> &Retains) {
DEBUG(dbgs() << "\n== ObjCARCOpt::VisitBottomUp ==\n");
-
+
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
PtrState &S = MyStates.getPtrTopDownState(Arg);
S.ClearKnownPositiveRefCount();
- switch (S.GetSeq()) {
+ Sequence OldSeq = S.GetSeq();
+
+ MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
+
+ switch (OldSeq) {
case S_Retain:
case S_CanRelease:
- S.RRI.ReverseInsertPts.clear();
+ if (OldSeq == S_Retain || ReleaseMetadata != 0)
+ S.RRI.ReverseInsertPts.clear();
// FALL THROUGH
case S_Use:
- S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
+ S.RRI.ReleaseMetadata = ReleaseMetadata;
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
Releases[Inst] = S.RRI;
ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_None);
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
+ DEBUG(dbgs() << "CanAlterRefCount: Seq: " << Seq << "; " << *Ptr
+ << "\n");
S.ClearKnownPositiveRefCount();
switch (Seq) {
case S_Retain:
switch (Seq) {
case S_CanRelease:
if (CanUse(Inst, Ptr, PA, Class)) {
+ DEBUG(dbgs() << "CanUse: Seq: " << Seq << "; " << *Ptr
+ << "\n");
S.SetSeq(S_Use);
ANNOTATE_TOPDOWN(Inst, Ptr, Seq, S_Use);
}
// bottom of the basic block.
ANNOTATE_TOPDOWN_BBEND(MyStates, BB);
+#ifdef ARC_ANNOTATIONS
+ if (!(EnableARCAnnotations && DisableCheckForCFGHazards))
+#endif
CheckForCFGHazards(BB, BBStates, MyStates);
return NestingDetected;
}
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
SmallVectorImpl<Instruction *> &DeadInsts,
- Module *M) {
+ Module *M) {
Type *ArgTy = Arg->getType();
Type *ParamTy = PointerType::getUnqual(Type::getInt8Ty(ArgTy->getContext()));
-
+
DEBUG(dbgs() << "== ObjCARCOpt::MoveCalls ==\n");
-
+
// Insert the new retain and release calls.
for (SmallPtrSet<Instruction *, 2>::const_iterator
PI = ReleasesToMove.ReverseInsertPts.begin(),
Call->setDoesNotThrow();
Call->setTailCall();
- DEBUG(dbgs() << "Inserting new Release: " << *Call << "\n"
+ DEBUG(dbgs() << "Inserting new Retain: " << *Call << "\n"
"At insertion point: " << *InsertPt << "\n");
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
DeadInsts.push_back(OrigRelease);
DEBUG(dbgs() << "Deleting release: " << *OrigRelease << "\n");
}
-
+
}
bool
/// Weak pointer optimizations.
void ObjCARCOpt::OptimizeWeakCalls(Function &F) {
DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeWeakCalls ==\n");
-
+
// First, do memdep-style RLE and S2L optimizations. We can't use memdep
// itself because it uses AliasAnalysis and we need to do provenance
// queries instead.
BB, Autorelease, DepInsts, Visited, PA);
if (DepInsts.size() != 1)
return 0;
-
+
CallInst *Retain =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
-
+
// Check that we found a retain with the same argument.
if (!Retain ||
!IsRetain(GetBasicInstructionClass(Retain)) ||
GetObjCArg(Retain) != Arg) {
return 0;
}
-
+
return Retain;
}
BB, Ret, DepInsts, V, PA);
if (DepInsts.size() != 1)
return 0;
-
+
CallInst *Autorelease =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
if (!Autorelease)
return 0;
if (GetObjCArg(Autorelease) != Arg)
return 0;
-
+
return Autorelease;
}
void ObjCARCOpt::OptimizeReturns(Function &F) {
if (!F.getReturnType()->isPointerTy())
return;
-
+
DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeReturns ==\n");
-
+
SmallPtrSet<Instruction *, 4> DependingInstructions;
SmallPtrSet<const BasicBlock *, 4> Visited;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
if (!Ret)
continue;
-
+
const Value *Arg = StripPointerCastsAndObjCCalls(Ret->getOperand(0));
-
- // Look for an ``autorelease'' instruction that is a predecssor of Ret and
+
+ // Look for an ``autorelease'' instruction that is a predecessor of Ret and
// dependent on Arg such that there are no instructions dependent on Arg
// that need a positive ref count in between the autorelease and Ret.
CallInst *Autorelease =
FindPredecessorAutoreleaseWithSafePath(Arg, BB, Ret,
DependingInstructions, Visited,
PA);
- if (Autorelease) {
- DependingInstructions.clear();
- Visited.clear();
-
- CallInst *Retain =
- FindPredecessorRetainWithSafePath(Arg, BB, Autorelease,
- DependingInstructions, Visited, PA);
- if (Retain) {
- DependingInstructions.clear();
- Visited.clear();
-
- // Check that there is nothing that can affect the reference count
- // between the retain and the call. Note that Retain need not be in BB.
- if (HasSafePathToPredecessorCall(Arg, Retain, DependingInstructions,
- Visited, PA)) {
- // If so, we can zap the retain and autorelease.
- Changed = true;
- ++NumRets;
- DEBUG(dbgs() << "Erasing: " << *Retain << "\nErasing: "
- << *Autorelease << "\n");
- EraseInstruction(Retain);
- EraseInstruction(Autorelease);
- }
- }
- }
-
DependingInstructions.clear();
Visited.clear();
+
+ if (!Autorelease)
+ continue;
+
+ CallInst *Retain =
+ FindPredecessorRetainWithSafePath(Arg, BB, Autorelease,
+ DependingInstructions, Visited, PA);
+ DependingInstructions.clear();
+ Visited.clear();
+
+ if (!Retain)
+ continue;
+
+ // Check that there is nothing that can affect the reference count
+ // between the retain and the call. Note that Retain need not be in BB.
+ bool HasSafePathToCall = HasSafePathToPredecessorCall(Arg, Retain,
+ DependingInstructions,
+ Visited, PA);
+ DependingInstructions.clear();
+ Visited.clear();
+
+ if (!HasSafePathToCall)
+ continue;
+
+ // If so, we can zap the retain and autorelease.
+ Changed = true;
+ ++NumRets;
+ DEBUG(dbgs() << "Erasing: " << *Retain << "\nErasing: "
+ << *Autorelease << "\n");
+ EraseInstruction(Retain);
+ EraseInstruction(Autorelease);
}
}
projects / oota-llvm.git / blobdiff