#define DEBUG_TYPE "objc-arc-opts"
#include "ObjCARC.h"
#include "ARCRuntimeEntryPoints.h"
#include "DependencyAnalysis.h"
#include "ObjCARCAliasAnalysis.h"
#include "ProvenanceAnalysis.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::objcarc;
namespace {
template<class KeyT, class ValueT>
class MapVector {
typedef DenseMap<KeyT, size_t> MapTy;
MapTy Map;
typedef std::vector<std::pair<KeyT, ValueT> > VectorTy;
VectorTy Vector;
public:
typedef typename VectorTy::iterator iterator;
typedef typename VectorTy::const_iterator const_iterator;
iterator begin() { return Vector.begin(); }
iterator end() { return Vector.end(); }
const_iterator begin() const { return Vector.begin(); }
const_iterator end() const { return Vector.end(); }
#ifdef XDEBUG
~MapVector() {
assert(Vector.size() >= Map.size()); for (typename MapTy::const_iterator I = Map.begin(), E = Map.end();
I != E; ++I) {
assert(I->second < Vector.size());
assert(Vector[I->second].first == I->first);
}
for (typename VectorTy::const_iterator I = Vector.begin(),
E = Vector.end(); I != E; ++I)
assert(!I->first ||
(Map.count(I->first) &&
Map[I->first] == size_t(I - Vector.begin())));
}
#endif
ValueT &operator[](const KeyT &Arg) {
std::pair<typename MapTy::iterator, bool> Pair =
Map.insert(std::make_pair(Arg, size_t(0)));
if (Pair.second) {
size_t Num = Vector.size();
Pair.first->second = Num;
Vector.push_back(std::make_pair(Arg, ValueT()));
return Vector[Num].second;
}
return Vector[Pair.first->second].second;
}
std::pair<iterator, bool>
insert(const std::pair<KeyT, ValueT> &InsertPair) {
std::pair<typename MapTy::iterator, bool> Pair =
Map.insert(std::make_pair(InsertPair.first, size_t(0)));
if (Pair.second) {
size_t Num = Vector.size();
Pair.first->second = Num;
Vector.push_back(InsertPair);
return std::make_pair(Vector.begin() + Num, true);
}
return std::make_pair(Vector.begin() + Pair.first->second, false);
}
iterator find(const KeyT &Key) {
typename MapTy::iterator It = Map.find(Key);
if (It == Map.end()) return Vector.end();
return Vector.begin() + It->second;
}
const_iterator find(const KeyT &Key) const {
typename MapTy::const_iterator It = Map.find(Key);
if (It == Map.end()) return Vector.end();
return Vector.begin() + It->second;
}
void blot(const KeyT &Key) {
typename MapTy::iterator It = Map.find(Key);
if (It == Map.end()) return;
Vector[It->second].first = KeyT();
Map.erase(It);
}
void clear() {
Map.clear();
Vector.clear();
}
};
}
static const Value *FindSingleUseIdentifiedObject(const Value *Arg) {
if (Arg->hasOneUse()) {
if (const BitCastInst *BC = dyn_cast<BitCastInst>(Arg))
return FindSingleUseIdentifiedObject(BC->getOperand(0));
if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Arg))
if (GEP->hasAllZeroIndices())
return FindSingleUseIdentifiedObject(GEP->getPointerOperand());
if (IsForwarding(GetBasicInstructionClass(Arg)))
return FindSingleUseIdentifiedObject(
cast<CallInst>(Arg)->getArgOperand(0));
if (!IsObjCIdentifiedObject(Arg))
return 0;
return Arg;
}
if (IsObjCIdentifiedObject(Arg)) {
for (Value::const_use_iterator UI = Arg->use_begin(), UE = Arg->use_end();
UI != UE; ++UI) {
const User *U = *UI;
if (!U->use_empty() || StripPointerCastsAndObjCCalls(U) != Arg)
return 0;
}
return Arg;
}
return 0;
}
static inline bool AreAnyUnderlyingObjectsAnAlloca(const Value *V) {
SmallPtrSet<const Value *, 4> Visited;
SmallVector<const Value *, 4> Worklist;
Worklist.push_back(V);
do {
const Value *P = Worklist.pop_back_val();
P = GetUnderlyingObjCPtr(P);
if (isa<AllocaInst>(P))
return true;
if (!Visited.insert(P))
continue;
if (const SelectInst *SI = dyn_cast<const SelectInst>(P)) {
Worklist.push_back(SI->getTrueValue());
Worklist.push_back(SI->getFalseValue());
continue;
}
if (const PHINode *PN = dyn_cast<const PHINode>(P)) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
Worklist.push_back(PN->getIncomingValue(i));
continue;
}
} while (!Worklist.empty());
return false;
}
STATISTIC(NumNoops, "Number of no-op objc calls eliminated");
STATISTIC(NumPartialNoops, "Number of partially no-op objc calls eliminated");
STATISTIC(NumAutoreleases,"Number of autoreleases converted to releases");
STATISTIC(NumRets, "Number of return value forwarding "
"retain+autoreleases eliminated");
STATISTIC(NumRRs, "Number of retain+release paths eliminated");
STATISTIC(NumPeeps, "Number of calls peephole-optimized");
#ifndef NDEBUG
STATISTIC(NumRetainsBeforeOpt,
"Number of retains before optimization");
STATISTIC(NumReleasesBeforeOpt,
"Number of releases before optimization");
STATISTIC(NumRetainsAfterOpt,
"Number of retains after optimization");
STATISTIC(NumReleasesAfterOpt,
"Number of releases after optimization");
#endif
namespace {
enum Sequence {
S_None,
S_Retain, S_CanRelease, S_Use, S_Stop, S_Release, S_MovableRelease };
raw_ostream &operator<<(raw_ostream &OS, const Sequence S)
LLVM_ATTRIBUTE_UNUSED;
raw_ostream &operator<<(raw_ostream &OS, const Sequence S) {
switch (S) {
case S_None:
return OS << "S_None";
case S_Retain:
return OS << "S_Retain";
case S_CanRelease:
return OS << "S_CanRelease";
case S_Use:
return OS << "S_Use";
case S_Release:
return OS << "S_Release";
case S_MovableRelease:
return OS << "S_MovableRelease";
case S_Stop:
return OS << "S_Stop";
}
llvm_unreachable("Unknown sequence type.");
}
}
static Sequence MergeSeqs(Sequence A, Sequence B, bool TopDown) {
if (A == B)
return A;
if (A == S_None || B == S_None)
return S_None;
if (A > B) std::swap(A, B);
if (TopDown) {
if ((A == S_Retain || A == S_CanRelease) &&
(B == S_CanRelease || B == S_Use))
return B;
} else {
if ((A == S_Use || A == S_CanRelease) &&
(B == S_Use || B == S_Release || B == S_Stop || B == S_MovableRelease))
return A;
if (A == S_Stop && (B == S_Release || B == S_MovableRelease))
return A;
if (A == S_Release && B == S_MovableRelease)
return A;
}
return S_None;
}
namespace {
struct RRInfo {
bool KnownSafe;
bool IsTailCallRelease;
MDNode *ReleaseMetadata;
SmallPtrSet<Instruction *, 2> Calls;
SmallPtrSet<Instruction *, 2> ReverseInsertPts;
bool CFGHazardAfflicted;
RRInfo() :
KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0),
CFGHazardAfflicted(false) {}
void clear();
bool Merge(const RRInfo &Other);
};
}
void RRInfo::clear() {
KnownSafe = false;
IsTailCallRelease = false;
ReleaseMetadata = 0;
Calls.clear();
ReverseInsertPts.clear();
CFGHazardAfflicted = false;
}
bool RRInfo::Merge(const RRInfo &Other) {
if (ReleaseMetadata != Other.ReleaseMetadata)
ReleaseMetadata = 0;
KnownSafe &= Other.KnownSafe;
IsTailCallRelease &= Other.IsTailCallRelease;
CFGHazardAfflicted |= Other.CFGHazardAfflicted;
Calls.insert(Other.Calls.begin(), Other.Calls.end());
bool Partial = ReverseInsertPts.size() != Other.ReverseInsertPts.size();
for (SmallPtrSet<Instruction *, 2>::const_iterator
I = Other.ReverseInsertPts.begin(),
E = Other.ReverseInsertPts.end(); I != E; ++I)
Partial |= ReverseInsertPts.insert(*I);
return Partial;
}
namespace {
class PtrState {
bool KnownPositiveRefCount;
bool Partial;
unsigned char Seq : 8;
RRInfo RRI;
public:
PtrState() : KnownPositiveRefCount(false), Partial(false),
Seq(S_None) {}
bool IsKnownSafe() const {
return RRI.KnownSafe;
}
void SetKnownSafe(const bool NewValue) {
RRI.KnownSafe = NewValue;
}
bool IsTailCallRelease() const {
return RRI.IsTailCallRelease;
}
void SetTailCallRelease(const bool NewValue) {
RRI.IsTailCallRelease = NewValue;
}
bool IsTrackingImpreciseReleases() const {
return RRI.ReleaseMetadata != 0;
}
const MDNode *GetReleaseMetadata() const {
return RRI.ReleaseMetadata;
}
void SetReleaseMetadata(MDNode *NewValue) {
RRI.ReleaseMetadata = NewValue;
}
bool IsCFGHazardAfflicted() const {
return RRI.CFGHazardAfflicted;
}
void SetCFGHazardAfflicted(const bool NewValue) {
RRI.CFGHazardAfflicted = NewValue;
}
void SetKnownPositiveRefCount() {
DEBUG(dbgs() << "Setting Known Positive.\n");
KnownPositiveRefCount = true;
}
void ClearKnownPositiveRefCount() {
DEBUG(dbgs() << "Clearing Known Positive.\n");
KnownPositiveRefCount = false;
}
bool HasKnownPositiveRefCount() const {
return KnownPositiveRefCount;
}
void SetSeq(Sequence NewSeq) {
DEBUG(dbgs() << "Old: " << Seq << "; New: " << NewSeq << "\n");
Seq = NewSeq;
}
Sequence GetSeq() const {
return static_cast<Sequence>(Seq);
}
void ClearSequenceProgress() {
ResetSequenceProgress(S_None);
}
void ResetSequenceProgress(Sequence NewSeq) {
DEBUG(dbgs() << "Resetting sequence progress.\n");
SetSeq(NewSeq);
Partial = false;
RRI.clear();
}
void Merge(const PtrState &Other, bool TopDown);
void InsertCall(Instruction *I) {
RRI.Calls.insert(I);
}
void InsertReverseInsertPt(Instruction *I) {
RRI.ReverseInsertPts.insert(I);
}
void ClearReverseInsertPts() {
RRI.ReverseInsertPts.clear();
}
bool HasReverseInsertPts() const {
return !RRI.ReverseInsertPts.empty();
}
const RRInfo &GetRRInfo() const {
return RRI;
}
};
}
void
PtrState::Merge(const PtrState &Other, bool TopDown) {
Seq = MergeSeqs(GetSeq(), Other.GetSeq(), TopDown);
KnownPositiveRefCount &= Other.KnownPositiveRefCount;
if (Seq == S_None) {
Partial = false;
RRI.clear();
} else if (Partial || Other.Partial) {
ClearSequenceProgress();
} else {
Partial = RRI.Merge(Other.RRI);
}
}
namespace {
class BBState {
unsigned TopDownPathCount;
unsigned BottomUpPathCount;
typedef MapVector<const Value *, PtrState> MapTy;
MapTy PerPtrTopDown;
MapTy PerPtrBottomUp;
SmallVector<BasicBlock *, 2> Preds;
SmallVector<BasicBlock *, 2> Succs;
public:
static const unsigned OverflowOccurredValue;
BBState() : TopDownPathCount(0), BottomUpPathCount(0) { }
typedef MapTy::iterator ptr_iterator;
typedef MapTy::const_iterator ptr_const_iterator;
ptr_iterator top_down_ptr_begin() { return PerPtrTopDown.begin(); }
ptr_iterator top_down_ptr_end() { return PerPtrTopDown.end(); }
ptr_const_iterator top_down_ptr_begin() const {
return PerPtrTopDown.begin();
}
ptr_const_iterator top_down_ptr_end() const {
return PerPtrTopDown.end();
}
ptr_iterator bottom_up_ptr_begin() { return PerPtrBottomUp.begin(); }
ptr_iterator bottom_up_ptr_end() { return PerPtrBottomUp.end(); }
ptr_const_iterator bottom_up_ptr_begin() const {
return PerPtrBottomUp.begin();
}
ptr_const_iterator bottom_up_ptr_end() const {
return PerPtrBottomUp.end();
}
void SetAsEntry() { TopDownPathCount = 1; }
void SetAsExit() { BottomUpPathCount = 1; }
PtrState &getPtrTopDownState(const Value *Arg) {
return PerPtrTopDown[Arg];
}
PtrState &getPtrBottomUpState(const Value *Arg) {
return PerPtrBottomUp[Arg];
}
ptr_iterator findPtrBottomUpState(const Value *Arg) {
return PerPtrBottomUp.find(Arg);
}
void clearBottomUpPointers() {
PerPtrBottomUp.clear();
}
void clearTopDownPointers() {
PerPtrTopDown.clear();
}
void InitFromPred(const BBState &Other);
void InitFromSucc(const BBState &Other);
void MergePred(const BBState &Other);
void MergeSucc(const BBState &Other);
bool GetAllPathCountWithOverflow(unsigned &PathCount) const {
if (TopDownPathCount == OverflowOccurredValue ||
BottomUpPathCount == OverflowOccurredValue)
return true;
unsigned long long Product =
(unsigned long long)TopDownPathCount*BottomUpPathCount;
return (Product >> 32) ||
((PathCount = Product) == OverflowOccurredValue);
}
typedef SmallVectorImpl<BasicBlock *>::const_iterator edge_iterator;
edge_iterator pred_begin() const { return Preds.begin(); }
edge_iterator pred_end() const { return Preds.end(); }
edge_iterator succ_begin() const { return Succs.begin(); }
edge_iterator succ_end() const { return Succs.end(); }
void addSucc(BasicBlock *Succ) { Succs.push_back(Succ); }
void addPred(BasicBlock *Pred) { Preds.push_back(Pred); }
bool isExit() const { return Succs.empty(); }
};
const unsigned BBState::OverflowOccurredValue = 0xffffffff;
}
void BBState::InitFromPred(const BBState &Other) {
PerPtrTopDown = Other.PerPtrTopDown;
TopDownPathCount = Other.TopDownPathCount;
}
void BBState::InitFromSucc(const BBState &Other) {
PerPtrBottomUp = Other.PerPtrBottomUp;
BottomUpPathCount = Other.BottomUpPathCount;
}
void BBState::MergePred(const BBState &Other) {
if (TopDownPathCount == OverflowOccurredValue)
return;
TopDownPathCount += Other.TopDownPathCount;
if (TopDownPathCount == OverflowOccurredValue) {
clearTopDownPointers();
return;
}
if (TopDownPathCount < Other.TopDownPathCount) {
TopDownPathCount = OverflowOccurredValue;
clearTopDownPointers();
return;
}
for (ptr_const_iterator MI = Other.top_down_ptr_begin(),
ME = Other.top_down_ptr_end(); MI != ME; ++MI) {
std::pair<ptr_iterator, bool> Pair = PerPtrTopDown.insert(*MI);
Pair.first->second.Merge(Pair.second ? PtrState() : MI->second,
true);
}
for (ptr_iterator MI = top_down_ptr_begin(),
ME = top_down_ptr_end(); MI != ME; ++MI)
if (Other.PerPtrTopDown.find(MI->first) == Other.PerPtrTopDown.end())
MI->second.Merge(PtrState(), true);
}
void BBState::MergeSucc(const BBState &Other) {
if (BottomUpPathCount == OverflowOccurredValue)
return;
BottomUpPathCount += Other.BottomUpPathCount;
if (BottomUpPathCount == OverflowOccurredValue) {
clearBottomUpPointers();
return;
}
if (BottomUpPathCount < Other.BottomUpPathCount) {
BottomUpPathCount = OverflowOccurredValue;
clearBottomUpPointers();
return;
}
for (ptr_const_iterator MI = Other.bottom_up_ptr_begin(),
ME = Other.bottom_up_ptr_end(); MI != ME; ++MI) {
std::pair<ptr_iterator, bool> Pair = PerPtrBottomUp.insert(*MI);
Pair.first->second.Merge(Pair.second ? PtrState() : MI->second,
false);
}
for (ptr_iterator MI = bottom_up_ptr_begin(),
ME = bottom_up_ptr_end(); MI != ME; ++MI)
if (Other.PerPtrBottomUp.find(MI->first) == Other.PerPtrBottomUp.end())
MI->second.Merge(PtrState(), false);
}
#ifndef NDEBUG
#define ARC_ANNOTATIONS
#endif
#ifdef ARC_ANNOTATIONS
#include "llvm/Support/CommandLine.h"
static cl::opt<bool>
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."));
static MDString *AppendMDNodeToSourcePtr(unsigned NodeId,
Value *Ptr) {
MDString *Hash = 0;
if (Instruction *Inst = dyn_cast<Instruction>(Ptr)) {
MDNode *Node;
if (!(Node = Inst->getMetadata(NodeId))) {
std::string Str;
raw_string_ostream os(Str);
os << "(" << Inst->getParent()->getParent()->getName() << ",%"
<< Inst->getName() << ")";
Hash = MDString::get(Inst->getContext(), os.str());
Inst->setMetadata(NodeId, MDNode::get(Inst->getContext(),Hash));
} else {
assert(Node->getNumOperands() == 1 &&
"An ARCAnnotationProvenanceSourceMDKind can only have 1 operand.");
Hash = cast<MDString>(Node->getOperand(0));
}
} else if (Argument *Arg = dyn_cast<Argument>(Ptr)) {
std::string str;
raw_string_ostream os(str);
os << "(" << Arg->getParent()->getName() << ",%" << Arg->getName()
<< ")";
Hash = MDString::get(Arg->getContext(), os.str());
}
return Hash;
}
static std::string SequenceToString(Sequence A) {
std::string str;
raw_string_ostream os(str);
os << A;
return os.str();
}
static MDString *SequenceToMDString(LLVMContext &Context,
Sequence A) {
return MDString::get(Context, SequenceToString(A));
}
static void AppendMDNodeToInstForPtr(unsigned NodeId,
Instruction *Inst,
Value *Ptr,
MDString *PtrSourceMDNodeID,
Sequence OldSeq,
Sequence NewSeq) {
MDNode *Node = 0;
Value *tmp[3] = {PtrSourceMDNodeID,
SequenceToMDString(Inst->getContext(),
OldSeq),
SequenceToMDString(Inst->getContext(),
NewSeq)};
Node = MDNode::get(Inst->getContext(),
ArrayRef<Value*>(tmp, 3));
Inst->setMetadata(NodeId, Node);
}
static void GenerateARCBBEntranceAnnotation(const char *Name, BasicBlock *BB,
Value *Ptr, Sequence Seq) {
if(!ARCAnnotationTargetIdentifier.empty() &&
!Ptr->getName().equals(ARCAnnotationTargetIdentifier))
return;
Module *M = BB->getParent()->getParent();
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
Type *I8XX = PointerType::getUnqual(I8X);
Type *Params[] = {I8XX, I8XX};
FunctionType *FTy = FunctionType::get(Type::getVoidTy(C),
ArrayRef<Type*>(Params, 2),
false);
Constant *Callee = M->getOrInsertFunction(Name, FTy);
IRBuilder<> Builder(BB, BB->getFirstInsertionPt());
Value *PtrName;
StringRef Tmp = Ptr->getName();
if (0 == (PtrName = M->getGlobalVariable(Tmp, true))) {
Value *ActualPtrName = Builder.CreateGlobalStringPtr(Tmp,
Tmp + "_STR");
PtrName = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
cast<Constant>(ActualPtrName), Tmp);
}
Value *S;
std::string SeqStr = SequenceToString(Seq);
if (0 == (S = M->getGlobalVariable(SeqStr, true))) {
Value *ActualPtrName = Builder.CreateGlobalStringPtr(SeqStr,
SeqStr + "_STR");
S = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
cast<Constant>(ActualPtrName), SeqStr);
}
Builder.CreateCall2(Callee, PtrName, S);
}
static void GenerateARCBBTerminatorAnnotation(const char *Name, BasicBlock *BB,
Value *Ptr, Sequence Seq) {
if(!ARCAnnotationTargetIdentifier.empty() &&
!Ptr->getName().equals(ARCAnnotationTargetIdentifier))
return;
Module *M = BB->getParent()->getParent();
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
Type *I8XX = PointerType::getUnqual(I8X);
Type *Params[] = {I8XX, I8XX};
FunctionType *FTy = FunctionType::get(Type::getVoidTy(C),
ArrayRef<Type*>(Params, 2),
false);
Constant *Callee = M->getOrInsertFunction(Name, FTy);
IRBuilder<> Builder(BB, llvm::prior(BB->end()));
Value *PtrName;
StringRef Tmp = Ptr->getName();
if (0 == (PtrName = M->getGlobalVariable(Tmp, true))) {
Value *ActualPtrName = Builder.CreateGlobalStringPtr(Tmp,
Tmp + "_STR");
PtrName = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
cast<Constant>(ActualPtrName), Tmp);
}
Value *S;
std::string SeqStr = SequenceToString(Seq);
if (0 == (S = M->getGlobalVariable(SeqStr, true))) {
Value *ActualPtrName = Builder.CreateGlobalStringPtr(SeqStr,
SeqStr + "_STR");
S = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
cast<Constant>(ActualPtrName), SeqStr);
}
Builder.CreateCall2(Callee, PtrName, S);
}
static void GenerateARCAnnotation(unsigned InstMDId,
unsigned PtrMDId,
Instruction *Inst,
Value *Ptr,
Sequence OldSeq,
Sequence NewSeq) {
if (EnableARCAnnotations) {
if(!ARCAnnotationTargetIdentifier.empty() &&
!Ptr->getName().equals(ARCAnnotationTargetIdentifier))
return;
MDString *SourcePtrMDNode =
AppendMDNodeToSourcePtr(PtrMDId, Ptr);
AppendMDNodeToInstForPtr(InstMDId, Inst, Ptr, SourcePtrMDNode, OldSeq,
NewSeq);
}
}
#define ANNOTATE_BOTTOMUP(inst, ptr, old, new) \
GenerateARCAnnotation(ARCAnnotationBottomUpMDKind, \
ARCAnnotationProvenanceSourceMDKind, (inst), \
const_cast<Value*>(ptr), (old), (new))
#define ANNOTATE_TOPDOWN(inst, ptr, old, new) \
GenerateARCAnnotation(ARCAnnotationTopDownMDKind, \
ARCAnnotationProvenanceSourceMDKind, (inst), \
const_cast<Value*>(ptr), (old), (new))
#define ANNOTATE_BB(_states, _bb, _name, _type, _direction) \
do { \
if (EnableARCAnnotations) { \
for(BBState::ptr_const_iterator I = (_states)._direction##_ptr_begin(), \
E = (_states)._direction##_ptr_end(); I != E; ++I) { \
Value *Ptr = const_cast<Value*>(I->first); \
Sequence Seq = I->second.GetSeq(); \
GenerateARCBB ## _type ## Annotation(_name, (_bb), Ptr, Seq); \
} \
} \
} while (0)
#define ANNOTATE_BOTTOMUP_BBSTART(_states, _basicblock) \
ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.bottomup.bbstart", \
Entrance, bottom_up)
#define ANNOTATE_BOTTOMUP_BBEND(_states, _basicblock) \
ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.bottomup.bbend", \
Terminator, bottom_up)
#define ANNOTATE_TOPDOWN_BBSTART(_states, _basicblock) \
ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.topdown.bbstart", \
Entrance, top_down)
#define ANNOTATE_TOPDOWN_BBEND(_states, _basicblock) \
ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.topdown.bbend", \
Terminator, top_down)
#else // !ARC_ANNOTATION
#define ANNOTATE_BOTTOMUP(inst, ptr, old, new)
#define ANNOTATE_TOPDOWN(inst, ptr, old, new)
#define ANNOTATE_BOTTOMUP_BBSTART(states, basicblock)
#define ANNOTATE_BOTTOMUP_BBEND(states, basicblock)
#define ANNOTATE_TOPDOWN_BBSTART(states, basicblock)
#define ANNOTATE_TOPDOWN_BBEND(states, basicblock)
#endif // !ARC_ANNOTATION
namespace {
class ObjCARCOpt : public FunctionPass {
bool Changed;
ProvenanceAnalysis PA;
ARCRuntimeEntryPoints EP;
DenseSet<const Value *> MultiOwnersSet;
bool Run;
unsigned UsedInThisFunction;
unsigned ImpreciseReleaseMDKind;
unsigned CopyOnEscapeMDKind;
unsigned NoObjCARCExceptionsMDKind;
#ifdef ARC_ANNOTATIONS
unsigned ARCAnnotationBottomUpMDKind;
unsigned ARCAnnotationTopDownMDKind;
unsigned ARCAnnotationProvenanceSourceMDKind;
#endif // ARC_ANNOATIONS
bool OptimizeRetainRVCall(Function &F, Instruction *RetainRV);
void OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV,
InstructionClass &Class);
void OptimizeIndividualCalls(Function &F);
void CheckForCFGHazards(const BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
BBState &MyStates) const;
bool VisitInstructionBottomUp(Instruction *Inst,
BasicBlock *BB,
MapVector<Value *, RRInfo> &Retains,
BBState &MyStates);
bool VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains);
bool VisitInstructionTopDown(Instruction *Inst,
DenseMap<Value *, RRInfo> &Releases,
BBState &MyStates);
bool VisitTopDown(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
DenseMap<Value *, RRInfo> &Releases);
bool Visit(Function &F,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases);
void MoveCalls(Value *Arg, RRInfo &RetainsToMove, RRInfo &ReleasesToMove,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
SmallVectorImpl<Instruction *> &DeadInsts,
Module *M);
bool ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M,
SmallVectorImpl<Instruction *> &NewRetains,
SmallVectorImpl<Instruction *> &NewReleases,
SmallVectorImpl<Instruction *> &DeadInsts,
RRInfo &RetainsToMove,
RRInfo &ReleasesToMove,
Value *Arg,
bool KnownSafe,
bool &AnyPairsCompletelyEliminated);
bool PerformCodePlacement(DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M);
void OptimizeWeakCalls(Function &F);
bool OptimizeSequences(Function &F);
void OptimizeReturns(Function &F);
#ifndef NDEBUG
void GatherStatistics(Function &F, bool AfterOptimization = false);
#endif
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual bool doInitialization(Module &M);
virtual bool runOnFunction(Function &F);
virtual void releaseMemory();
public:
static char ID;
ObjCARCOpt() : FunctionPass(ID) {
initializeObjCARCOptPass(*PassRegistry::getPassRegistry());
}
};
}
char ObjCARCOpt::ID = 0;
INITIALIZE_PASS_BEGIN(ObjCARCOpt,
"objc-arc", "ObjC ARC optimization", false, false)
INITIALIZE_PASS_DEPENDENCY(ObjCARCAliasAnalysis)
INITIALIZE_PASS_END(ObjCARCOpt,
"objc-arc", "ObjC ARC optimization", false, false)
Pass *llvm::createObjCARCOptPass() {
return new ObjCARCOpt();
}
void ObjCARCOpt::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<ObjCARCAliasAnalysis>();
AU.addRequired<AliasAnalysis>();
AU.setPreservesCFG();
}
bool
ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
const Value *Arg = GetObjCArg(RetainRV);
ImmutableCallSite CS(Arg);
if (const Instruction *Call = CS.getInstruction()) {
if (Call->getParent() == RetainRV->getParent()) {
BasicBlock::const_iterator I = Call;
++I;
while (IsNoopInstruction(I)) ++I;
if (&*I == RetainRV)
return false;
} else if (const InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
BasicBlock *RetainRVParent = RetainRV->getParent();
if (II->getNormalDest() == RetainRVParent) {
BasicBlock::const_iterator I = RetainRVParent->begin();
while (IsNoopInstruction(I)) ++I;
if (&*I == RetainRV)
return false;
}
}
}
BasicBlock::iterator I = RetainRV, Begin = RetainRV->getParent()->begin();
if (I != Begin) {
do --I; while (I != Begin && IsNoopInstruction(I));
if (GetBasicInstructionClass(I) == IC_AutoreleaseRV &&
GetObjCArg(I) == Arg) {
Changed = true;
++NumPeeps;
DEBUG(dbgs() << "Erasing autoreleaseRV,retainRV pair: " << *I << "\n"
<< "Erasing " << *RetainRV << "\n");
EraseInstruction(I);
EraseInstruction(RetainRV);
return true;
}
}
Changed = true;
++NumPeeps;
DEBUG(dbgs() << "Transforming objc_retainAutoreleasedReturnValue => "
"objc_retain since the operand is not a return value.\n"
"Old = " << *RetainRV << "\n");
Constant *NewDecl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
cast<CallInst>(RetainRV)->setCalledFunction(NewDecl);
DEBUG(dbgs() << "New = " << *RetainRV << "\n");
return false;
}
void
ObjCARCOpt::OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV,
InstructionClass &Class) {
const Value *Ptr = GetObjCArg(AutoreleaseRV);
SmallVector<const Value *, 2> Users;
Users.push_back(Ptr);
do {
Ptr = Users.pop_back_val();
for (Value::const_use_iterator UI = Ptr->use_begin(), UE = Ptr->use_end();
UI != UE; ++UI) {
const User *I = *UI;
if (isa<ReturnInst>(I) || GetBasicInstructionClass(I) == IC_RetainRV)
return;
if (isa<BitCastInst>(I))
Users.push_back(I);
}
} while (!Users.empty());
Changed = true;
++NumPeeps;
DEBUG(dbgs() << "Transforming objc_autoreleaseReturnValue => "
"objc_autorelease since its operand is not used as a return "
"value.\n"
"Old = " << *AutoreleaseRV << "\n");
CallInst *AutoreleaseRVCI = cast<CallInst>(AutoreleaseRV);
Constant *NewDecl = EP.get(ARCRuntimeEntryPoints::EPT_Autorelease);
AutoreleaseRVCI->setCalledFunction(NewDecl);
AutoreleaseRVCI->setTailCall(false); Class = IC_Autorelease;
DEBUG(dbgs() << "New: " << *AutoreleaseRV << "\n");
}
void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeIndividualCalls ==\n");
UsedInThisFunction = 0;
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
InstructionClass Class = GetBasicInstructionClass(Inst);
DEBUG(dbgs() << "Visiting: Class: " << Class << "; " << *Inst << "\n");
switch (Class) {
default: break;
case IC_NoopCast:
Changed = true;
++NumNoops;
DEBUG(dbgs() << "Erasing no-op cast: " << *Inst << "\n");
EraseInstruction(Inst);
continue;
case IC_StoreWeak:
case IC_LoadWeak:
case IC_LoadWeakRetained:
case IC_InitWeak:
case IC_DestroyWeak: {
CallInst *CI = cast<CallInst>(Inst);
if (IsNullOrUndef(CI->getArgOperand(0))) {
Changed = true;
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
Constant::getNullValue(Ty),
CI);
llvm::Value *NewValue = UndefValue::get(CI->getType());
DEBUG(dbgs() << "A null pointer-to-weak-pointer is undefined behavior."
"\nOld = " << *CI << "\nNew = " << *NewValue << "\n");
CI->replaceAllUsesWith(NewValue);
CI->eraseFromParent();
continue;
}
break;
}
case IC_CopyWeak:
case IC_MoveWeak: {
CallInst *CI = cast<CallInst>(Inst);
if (IsNullOrUndef(CI->getArgOperand(0)) ||
IsNullOrUndef(CI->getArgOperand(1))) {
Changed = true;
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
Constant::getNullValue(Ty),
CI);
llvm::Value *NewValue = UndefValue::get(CI->getType());
DEBUG(dbgs() << "A null pointer-to-weak-pointer is undefined behavior."
"\nOld = " << *CI << "\nNew = " << *NewValue << "\n");
CI->replaceAllUsesWith(NewValue);
CI->eraseFromParent();
continue;
}
break;
}
case IC_RetainRV:
if (OptimizeRetainRVCall(F, Inst))
continue;
break;
case IC_AutoreleaseRV:
OptimizeAutoreleaseRVCall(F, Inst, Class);
break;
}
if (IsAutorelease(Class) && Inst->use_empty()) {
CallInst *Call = cast<CallInst>(Inst);
const Value *Arg = Call->getArgOperand(0);
Arg = FindSingleUseIdentifiedObject(Arg);
if (Arg) {
Changed = true;
++NumAutoreleases;
LLVMContext &C = Inst->getContext();
Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Release);
CallInst *NewCall = CallInst::Create(Decl, Call->getArgOperand(0), "",
Call);
NewCall->setMetadata(ImpreciseReleaseMDKind, MDNode::get(C, None));
DEBUG(dbgs() << "Replacing autorelease{,RV}(x) with objc_release(x) "
"since x is otherwise unused.\nOld: " << *Call << "\nNew: "
<< *NewCall << "\n");
EraseInstruction(Call);
Inst = NewCall;
Class = IC_Release;
}
}
if (IsAlwaysTail(Class)) {
Changed = true;
DEBUG(dbgs() << "Adding tail keyword to function since it can never be "
"passed stack args: " << *Inst << "\n");
cast<CallInst>(Inst)->setTailCall();
}
if (IsNeverTail(Class)) {
Changed = true;
DEBUG(dbgs() << "Removing tail keyword from function: " << *Inst <<
"\n");
cast<CallInst>(Inst)->setTailCall(false);
}
if (IsNoThrow(Class)) {
Changed = true;
DEBUG(dbgs() << "Found no throw class. Setting nounwind on: " << *Inst
<< "\n");
cast<CallInst>(Inst)->setDoesNotThrow();
}
if (!IsNoopOnNull(Class)) {
UsedInThisFunction |= 1 << Class;
continue;
}
const Value *Arg = GetObjCArg(Inst);
if (IsNullOrUndef(Arg)) {
Changed = true;
++NumNoops;
DEBUG(dbgs() << "ARC calls with null are no-ops. Erasing: " << *Inst
<< "\n");
EraseInstruction(Inst);
continue;
}
UsedInThisFunction |= 1 << Class;
SmallVector<std::pair<Instruction *, const Value *>, 4> Worklist;
Worklist.push_back(std::make_pair(Inst, Arg));
do {
std::pair<Instruction *, const Value *> Pair = Worklist.pop_back_val();
Inst = Pair.first;
Arg = Pair.second;
const PHINode *PN = dyn_cast<PHINode>(Arg);
if (!PN) continue;
bool HasNull = false;
bool HasCriticalEdges = false;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming =
StripPointerCastsAndObjCCalls(PN->getIncomingValue(i));
if (IsNullOrUndef(Incoming))
HasNull = true;
else if (cast<TerminatorInst>(PN->getIncomingBlock(i)->back())
.getNumSuccessors() != 1) {
HasCriticalEdges = true;
break;
}
}
if (!HasCriticalEdges && HasNull) {
SmallPtrSet<Instruction *, 4> DependingInstructions;
SmallPtrSet<const BasicBlock *, 4> Visited;
switch (Class) {
case IC_Retain:
case IC_RetainBlock:
break;
case IC_Release:
FindDependencies(NeedsPositiveRetainCount, Arg,
Inst->getParent(), Inst,
DependingInstructions, Visited, PA);
break;
case IC_Autorelease:
FindDependencies(AutoreleasePoolBoundary, Arg,
Inst->getParent(), Inst,
DependingInstructions, Visited, PA);
break;
case IC_RetainRV:
case IC_AutoreleaseRV:
continue;
default:
llvm_unreachable("Invalid dependence flavor");
}
if (DependingInstructions.size() == 1 &&
*DependingInstructions.begin() == PN) {
Changed = true;
++NumPartialNoops;
CallInst *CInst = cast<CallInst>(Inst);
Type *ParamTy = CInst->getArgOperand(0)->getType();
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming =
StripPointerCastsAndObjCCalls(PN->getIncomingValue(i));
if (!IsNullOrUndef(Incoming)) {
CallInst *Clone = cast<CallInst>(CInst->clone());
Value *Op = PN->getIncomingValue(i);
Instruction *InsertPos = &PN->getIncomingBlock(i)->back();
if (Op->getType() != ParamTy)
Op = new BitCastInst(Op, ParamTy, "", InsertPos);
Clone->setArgOperand(0, Op);
Clone->insertBefore(InsertPos);
DEBUG(dbgs() << "Cloning "
<< *CInst << "\n"
"And inserting clone at " << *InsertPos << "\n");
Worklist.push_back(std::make_pair(Clone, Incoming));
}
}
DEBUG(dbgs() << "Erasing: " << *CInst << "\n");
EraseInstruction(CInst);
continue;
}
}
} while (!Worklist.empty());
}
}
static void CheckForUseCFGHazard(const Sequence SuccSSeq,
const bool SuccSRRIKnownSafe,
PtrState &S,
bool &SomeSuccHasSame,
bool &AllSuccsHaveSame,
bool &NotAllSeqEqualButKnownSafe,
bool &ShouldContinue) {
switch (SuccSSeq) {
case S_CanRelease: {
if (!S.IsKnownSafe() && !SuccSRRIKnownSafe) {
S.ClearSequenceProgress();
break;
}
S.SetCFGHazardAfflicted(true);
ShouldContinue = true;
break;
}
case S_Use:
SomeSuccHasSame = true;
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
if (!S.IsKnownSafe() && !SuccSRRIKnownSafe)
AllSuccsHaveSame = false;
else
NotAllSeqEqualButKnownSafe = true;
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
case S_None:
llvm_unreachable("This should have been handled earlier.");
}
}
static void CheckForCanReleaseCFGHazard(const Sequence SuccSSeq,
const bool SuccSRRIKnownSafe,
PtrState &S,
bool &SomeSuccHasSame,
bool &AllSuccsHaveSame,
bool &NotAllSeqEqualButKnownSafe) {
switch (SuccSSeq) {
case S_CanRelease:
SomeSuccHasSame = true;
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
case S_Use:
if (!S.IsKnownSafe() && !SuccSRRIKnownSafe)
AllSuccsHaveSame = false;
else
NotAllSeqEqualButKnownSafe = true;
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
case S_None:
llvm_unreachable("This should have been handled earlier.");
}
}
void
ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
BBState &MyStates) const {
for (BBState::ptr_iterator I = MyStates.top_down_ptr_begin(),
E = MyStates.top_down_ptr_end(); I != E; ++I) {
PtrState &S = I->second;
const Sequence Seq = I->second.GetSeq();
if (Seq == S_None)
continue;
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;
bool NotAllSeqEqualButKnownSafe = false;
succ_const_iterator SI(TI), SE(TI, false);
for (; SI != SE; ++SI) {
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 (SuccSSeq == S_None) {
S.ClearSequenceProgress();
continue;
}
const bool SuccSRRIKnownSafe = SuccS.IsKnownSafe();
switch(S.GetSeq()) {
case S_Use: {
bool ShouldContinue = false;
CheckForUseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S, SomeSuccHasSame,
AllSuccsHaveSame, NotAllSeqEqualButKnownSafe,
ShouldContinue);
if (ShouldContinue)
continue;
break;
}
case S_CanRelease: {
CheckForCanReleaseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S,
SomeSuccHasSame, AllSuccsHaveSame,
NotAllSeqEqualButKnownSafe);
break;
}
case S_Retain:
case S_None:
case S_Stop:
case S_Release:
case S_MovableRelease:
break;
}
}
if (SomeSuccHasSame && !AllSuccsHaveSame) {
S.ClearSequenceProgress();
} else if (NotAllSeqEqualButKnownSafe) {
S.SetCFGHazardAfflicted(true);
}
}
}
bool
ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst,
BasicBlock *BB,
MapVector<Value *, RRInfo> &Retains,
BBState &MyStates) {
bool NestingDetected = false;
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
DEBUG(dbgs() << "Class: " << Class << "\n");
switch (Class) {
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
if (S.GetSeq() == S_Release || S.GetSeq() == S_MovableRelease) {
DEBUG(dbgs() << "Found nested releases (i.e. a release pair)\n");
NestingDetected = true;
}
MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
Sequence NewSeq = ReleaseMetadata ? S_MovableRelease : S_Release;
ANNOTATE_BOTTOMUP(Inst, Arg, S.GetSeq(), NewSeq);
S.ResetSequenceProgress(NewSeq);
S.SetReleaseMetadata(ReleaseMetadata);
S.SetKnownSafe(S.HasKnownPositiveRefCount());
S.SetTailCallRelease(cast<CallInst>(Inst)->isTailCall());
S.InsertCall(Inst);
S.SetKnownPositiveRefCount();
break;
}
case IC_RetainBlock:
break;
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
S.SetKnownPositiveRefCount();
Sequence OldSeq = S.GetSeq();
switch (OldSeq) {
case S_Stop:
case S_Release:
case S_MovableRelease:
case S_Use:
if (OldSeq != S_Use || S.IsTrackingImpreciseReleases())
S.ClearReverseInsertPts();
case S_CanRelease:
if (Class != IC_RetainRV)
Retains[Inst] = S.GetRRInfo();
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
ANNOTATE_BOTTOMUP(Inst, Arg, OldSeq, S.GetSeq());
break;
}
case IC_AutoreleasepoolPop:
MyStates.clearBottomUpPointers();
return NestingDetected;
case IC_AutoreleasepoolPush:
case IC_None:
return NestingDetected;
case IC_User:
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (AreAnyUnderlyingObjectsAnAlloca(SI->getPointerOperand())) {
BBState::ptr_iterator I = MyStates.findPtrBottomUpState(
StripPointerCastsAndObjCCalls(SI->getValueOperand()));
if (I != MyStates.bottom_up_ptr_end())
MultiOwnersSet.insert(I->first);
}
}
break;
default:
break;
}
for (BBState::ptr_iterator MI = MyStates.bottom_up_ptr_begin(),
ME = MyStates.bottom_up_ptr_end(); MI != ME; ++MI) {
const Value *Ptr = MI->first;
if (Ptr == Arg)
continue; PtrState &S = MI->second;
Sequence Seq = S.GetSeq();
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
DEBUG(dbgs() << "CanAlterRefCount: Seq: " << Seq << "; " << *Ptr
<< "\n");
S.ClearKnownPositiveRefCount();
switch (Seq) {
case S_Use:
S.SetSeq(S_CanRelease);
ANNOTATE_BOTTOMUP(Inst, Ptr, Seq, S.GetSeq());
continue;
case S_CanRelease:
case S_Release:
case S_MovableRelease:
case S_Stop:
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
}
switch (Seq) {
case S_Release:
case S_MovableRelease:
if (CanUse(Inst, Ptr, PA, Class)) {
DEBUG(dbgs() << "CanUse: Seq: " << Seq << "; " << *Ptr
<< "\n");
assert(!S.HasReverseInsertPts());
if (isa<InvokeInst>(Inst))
S.InsertReverseInsertPt(BB->getFirstInsertionPt());
else
S.InsertReverseInsertPt(llvm::next(BasicBlock::iterator(Inst)));
S.SetSeq(S_Use);
ANNOTATE_BOTTOMUP(Inst, Ptr, Seq, S_Use);
} else if (Seq == S_Release && IsUser(Class)) {
DEBUG(dbgs() << "PreciseReleaseUse: Seq: " << Seq << "; " << *Ptr
<< "\n");
S.SetSeq(S_Stop);
ANNOTATE_BOTTOMUP(Inst, Ptr, S_Release, S_Stop);
assert(!S.HasReverseInsertPts());
if (isa<InvokeInst>(Inst))
S.InsertReverseInsertPt(BB->getFirstInsertionPt());
else
S.InsertReverseInsertPt(llvm::next(BasicBlock::iterator(Inst)));
}
break;
case S_Stop:
if (CanUse(Inst, Ptr, PA, Class)) {
DEBUG(dbgs() << "PreciseStopUse: Seq: " << Seq << "; " << *Ptr
<< "\n");
S.SetSeq(S_Use);
ANNOTATE_BOTTOMUP(Inst, Ptr, Seq, S_Use);
}
break;
case S_CanRelease:
case S_Use:
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
}
return NestingDetected;
}
bool
ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains) {
DEBUG(dbgs() << "\n== ObjCARCOpt::VisitBottomUp ==\n");
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
BBState::edge_iterator SI(MyStates.succ_begin()),
SE(MyStates.succ_end());
if (SI != SE) {
const BasicBlock *Succ = *SI;
DenseMap<const BasicBlock *, BBState>::iterator I = BBStates.find(Succ);
assert(I != BBStates.end());
MyStates.InitFromSucc(I->second);
++SI;
for (; SI != SE; ++SI) {
Succ = *SI;
I = BBStates.find(Succ);
assert(I != BBStates.end());
MyStates.MergeSucc(I->second);
}
}
ANNOTATE_BOTTOMUP_BBEND(MyStates, BB);
for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; --I) {
Instruction *Inst = llvm::prior(I);
if (isa<InvokeInst>(Inst))
continue;
DEBUG(dbgs() << "Visiting " << *Inst << "\n");
NestingDetected |= VisitInstructionBottomUp(Inst, BB, Retains, MyStates);
}
for (BBState::edge_iterator PI(MyStates.pred_begin()),
PE(MyStates.pred_end()); PI != PE; ++PI) {
BasicBlock *Pred = *PI;
if (InvokeInst *II = dyn_cast<InvokeInst>(&Pred->back()))
NestingDetected |= VisitInstructionBottomUp(II, BB, Retains, MyStates);
}
ANNOTATE_BOTTOMUP_BBSTART(MyStates, BB);
return NestingDetected;
}
bool
ObjCARCOpt::VisitInstructionTopDown(Instruction *Inst,
DenseMap<Value *, RRInfo> &Releases,
BBState &MyStates) {
bool NestingDetected = false;
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
switch (Class) {
case IC_RetainBlock:
break;
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
if (Class != IC_RetainRV) {
if (S.GetSeq() == S_Retain)
NestingDetected = true;
ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_Retain);
S.ResetSequenceProgress(S_Retain);
S.SetKnownSafe(S.HasKnownPositiveRefCount());
S.InsertCall(Inst);
}
S.SetKnownPositiveRefCount();
break;
}
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
S.ClearKnownPositiveRefCount();
Sequence OldSeq = S.GetSeq();
MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
switch (OldSeq) {
case S_Retain:
case S_CanRelease:
if (OldSeq == S_Retain || ReleaseMetadata != 0)
S.ClearReverseInsertPts();
case S_Use:
S.SetReleaseMetadata(ReleaseMetadata);
S.SetTailCallRelease(cast<CallInst>(Inst)->isTailCall());
Releases[Inst] = S.GetRRInfo();
ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_None);
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
break;
}
case IC_AutoreleasepoolPop:
MyStates.clearTopDownPointers();
return NestingDetected;
case IC_AutoreleasepoolPush:
case IC_None:
return NestingDetected;
default:
break;
}
for (BBState::ptr_iterator MI = MyStates.top_down_ptr_begin(),
ME = MyStates.top_down_ptr_end(); MI != ME; ++MI) {
const Value *Ptr = MI->first;
if (Ptr == Arg)
continue; PtrState &S = MI->second;
Sequence Seq = S.GetSeq();
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
DEBUG(dbgs() << "CanAlterRefCount: Seq: " << Seq << "; " << *Ptr
<< "\n");
S.ClearKnownPositiveRefCount();
switch (Seq) {
case S_Retain:
S.SetSeq(S_CanRelease);
ANNOTATE_TOPDOWN(Inst, Ptr, Seq, S_CanRelease);
assert(!S.HasReverseInsertPts());
S.InsertReverseInsertPt(Inst);
continue;
case S_Use:
case S_CanRelease:
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
}
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);
}
break;
case S_Retain:
case S_Use:
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
}
return NestingDetected;
}
bool
ObjCARCOpt::VisitTopDown(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
DenseMap<Value *, RRInfo> &Releases) {
DEBUG(dbgs() << "\n== ObjCARCOpt::VisitTopDown ==\n");
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
BBState::edge_iterator PI(MyStates.pred_begin()),
PE(MyStates.pred_end());
if (PI != PE) {
const BasicBlock *Pred = *PI;
DenseMap<const BasicBlock *, BBState>::iterator I = BBStates.find(Pred);
assert(I != BBStates.end());
MyStates.InitFromPred(I->second);
++PI;
for (; PI != PE; ++PI) {
Pred = *PI;
I = BBStates.find(Pred);
assert(I != BBStates.end());
MyStates.MergePred(I->second);
}
}
ANNOTATE_TOPDOWN_BBSTART(MyStates, BB);
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
Instruction *Inst = I;
DEBUG(dbgs() << "Visiting " << *Inst << "\n");
NestingDetected |= VisitInstructionTopDown(Inst, Releases, MyStates);
}
ANNOTATE_TOPDOWN_BBEND(MyStates, BB);
#ifdef ARC_ANNOTATIONS
if (!(EnableARCAnnotations && DisableCheckForCFGHazards))
#endif
CheckForCFGHazards(BB, BBStates, MyStates);
return NestingDetected;
}
static void
ComputePostOrders(Function &F,
SmallVectorImpl<BasicBlock *> &PostOrder,
SmallVectorImpl<BasicBlock *> &ReverseCFGPostOrder,
unsigned NoObjCARCExceptionsMDKind,
DenseMap<const BasicBlock *, BBState> &BBStates) {
SmallPtrSet<BasicBlock *, 16> Visited;
SmallPtrSet<BasicBlock *, 16> OnStack;
SmallVector<std::pair<BasicBlock *, succ_iterator>, 16> SuccStack;
BasicBlock *EntryBB = &F.getEntryBlock();
BBState &MyStates = BBStates[EntryBB];
MyStates.SetAsEntry();
TerminatorInst *EntryTI = cast<TerminatorInst>(&EntryBB->back());
SuccStack.push_back(std::make_pair(EntryBB, succ_iterator(EntryTI)));
Visited.insert(EntryBB);
OnStack.insert(EntryBB);
do {
dfs_next_succ:
BasicBlock *CurrBB = SuccStack.back().first;
TerminatorInst *TI = cast<TerminatorInst>(&CurrBB->back());
succ_iterator SE(TI, false);
while (SuccStack.back().second != SE) {
BasicBlock *SuccBB = *SuccStack.back().second++;
if (Visited.insert(SuccBB)) {
TerminatorInst *TI = cast<TerminatorInst>(&SuccBB->back());
SuccStack.push_back(std::make_pair(SuccBB, succ_iterator(TI)));
BBStates[CurrBB].addSucc(SuccBB);
BBState &SuccStates = BBStates[SuccBB];
SuccStates.addPred(CurrBB);
OnStack.insert(SuccBB);
goto dfs_next_succ;
}
if (!OnStack.count(SuccBB)) {
BBStates[CurrBB].addSucc(SuccBB);
BBStates[SuccBB].addPred(CurrBB);
}
}
OnStack.erase(CurrBB);
PostOrder.push_back(CurrBB);
SuccStack.pop_back();
} while (!SuccStack.empty());
Visited.clear();
SmallVector<std::pair<BasicBlock *, BBState::edge_iterator>, 16> PredStack;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
BasicBlock *ExitBB = I;
BBState &MyStates = BBStates[ExitBB];
if (!MyStates.isExit())
continue;
MyStates.SetAsExit();
PredStack.push_back(std::make_pair(ExitBB, MyStates.pred_begin()));
Visited.insert(ExitBB);
while (!PredStack.empty()) {
reverse_dfs_next_succ:
BBState::edge_iterator PE = BBStates[PredStack.back().first].pred_end();
while (PredStack.back().second != PE) {
BasicBlock *BB = *PredStack.back().second++;
if (Visited.insert(BB)) {
PredStack.push_back(std::make_pair(BB, BBStates[BB].pred_begin()));
goto reverse_dfs_next_succ;
}
}
ReverseCFGPostOrder.push_back(PredStack.pop_back_val().first);
}
}
}
bool
ObjCARCOpt::Visit(Function &F,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases) {
SmallVector<BasicBlock *, 16> PostOrder;
SmallVector<BasicBlock *, 16> ReverseCFGPostOrder;
ComputePostOrders(F, PostOrder, ReverseCFGPostOrder,
NoObjCARCExceptionsMDKind,
BBStates);
bool BottomUpNestingDetected = false;
for (SmallVectorImpl<BasicBlock *>::const_reverse_iterator I =
ReverseCFGPostOrder.rbegin(), E = ReverseCFGPostOrder.rend();
I != E; ++I)
BottomUpNestingDetected |= VisitBottomUp(*I, BBStates, Retains);
bool TopDownNestingDetected = false;
for (SmallVectorImpl<BasicBlock *>::const_reverse_iterator I =
PostOrder.rbegin(), E = PostOrder.rend();
I != E; ++I)
TopDownNestingDetected |= VisitTopDown(*I, BBStates, Releases);
return TopDownNestingDetected && BottomUpNestingDetected;
}
void ObjCARCOpt::MoveCalls(Value *Arg,
RRInfo &RetainsToMove,
RRInfo &ReleasesToMove,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
SmallVectorImpl<Instruction *> &DeadInsts,
Module *M) {
Type *ArgTy = Arg->getType();
Type *ParamTy = PointerType::getUnqual(Type::getInt8Ty(ArgTy->getContext()));
DEBUG(dbgs() << "== ObjCARCOpt::MoveCalls ==\n");
for (SmallPtrSet<Instruction *, 2>::const_iterator
PI = ReleasesToMove.ReverseInsertPts.begin(),
PE = ReleasesToMove.ReverseInsertPts.end(); PI != PE; ++PI) {
Instruction *InsertPt = *PI;
Value *MyArg = ArgTy == ParamTy ? Arg :
new BitCastInst(Arg, ParamTy, "", InsertPt);
Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
CallInst *Call = CallInst::Create(Decl, MyArg, "", InsertPt);
Call->setDoesNotThrow();
Call->setTailCall();
DEBUG(dbgs() << "Inserting new Retain: " << *Call << "\n"
"At insertion point: " << *InsertPt << "\n");
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
PI = RetainsToMove.ReverseInsertPts.begin(),
PE = RetainsToMove.ReverseInsertPts.end(); PI != PE; ++PI) {
Instruction *InsertPt = *PI;
Value *MyArg = ArgTy == ParamTy ? Arg :
new BitCastInst(Arg, ParamTy, "", InsertPt);
Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Release);
CallInst *Call = CallInst::Create(Decl, MyArg, "", InsertPt);
if (MDNode *M = ReleasesToMove.ReleaseMetadata)
Call->setMetadata(ImpreciseReleaseMDKind, M);
Call->setDoesNotThrow();
if (ReleasesToMove.IsTailCallRelease)
Call->setTailCall();
DEBUG(dbgs() << "Inserting new Release: " << *Call << "\n"
"At insertion point: " << *InsertPt << "\n");
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
AI = RetainsToMove.Calls.begin(),
AE = RetainsToMove.Calls.end(); AI != AE; ++AI) {
Instruction *OrigRetain = *AI;
Retains.blot(OrigRetain);
DeadInsts.push_back(OrigRetain);
DEBUG(dbgs() << "Deleting retain: " << *OrigRetain << "\n");
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
AI = ReleasesToMove.Calls.begin(),
AE = ReleasesToMove.Calls.end(); AI != AE; ++AI) {
Instruction *OrigRelease = *AI;
Releases.erase(OrigRelease);
DeadInsts.push_back(OrigRelease);
DEBUG(dbgs() << "Deleting release: " << *OrigRelease << "\n");
}
}
bool
ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
&BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M,
SmallVectorImpl<Instruction *> &NewRetains,
SmallVectorImpl<Instruction *> &NewReleases,
SmallVectorImpl<Instruction *> &DeadInsts,
RRInfo &RetainsToMove,
RRInfo &ReleasesToMove,
Value *Arg,
bool KnownSafe,
bool &AnyPairsCompletelyEliminated) {
bool KnownSafeTD = true, KnownSafeBU = true;
bool MultipleOwners = false;
bool CFGHazardAfflicted = false;
unsigned OldDelta = 0;
unsigned NewDelta = 0;
unsigned OldCount = 0;
unsigned NewCount = 0;
bool FirstRelease = true;
for (;;) {
for (SmallVectorImpl<Instruction *>::const_iterator
NI = NewRetains.begin(), NE = NewRetains.end(); NI != NE; ++NI) {
Instruction *NewRetain = *NI;
MapVector<Value *, RRInfo>::const_iterator It = Retains.find(NewRetain);
assert(It != Retains.end());
const RRInfo &NewRetainRRI = It->second;
KnownSafeTD &= NewRetainRRI.KnownSafe;
MultipleOwners =
MultipleOwners || MultiOwnersSet.count(GetObjCArg(NewRetain));
for (SmallPtrSet<Instruction *, 2>::const_iterator
LI = NewRetainRRI.Calls.begin(),
LE = NewRetainRRI.Calls.end(); LI != LE; ++LI) {
Instruction *NewRetainRelease = *LI;
DenseMap<Value *, RRInfo>::const_iterator Jt =
Releases.find(NewRetainRelease);
if (Jt == Releases.end())
return false;
const RRInfo &NewRetainReleaseRRI = Jt->second;
if (!NewRetainReleaseRRI.Calls.count(NewRetain))
return false;
if (ReleasesToMove.Calls.insert(NewRetainRelease)) {
const BBState &NRRBBState = BBStates[NewRetainRelease->getParent()];
unsigned PathCount = BBState::OverflowOccurredValue;
if (NRRBBState.GetAllPathCountWithOverflow(PathCount))
return false;
assert(PathCount != BBState::OverflowOccurredValue &&
"PathCount at this point can not be "
"OverflowOccurredValue.");
OldDelta -= PathCount;
if (FirstRelease) {
ReleasesToMove.ReleaseMetadata =
NewRetainReleaseRRI.ReleaseMetadata;
ReleasesToMove.IsTailCallRelease =
NewRetainReleaseRRI.IsTailCallRelease;
FirstRelease = false;
} else {
if (ReleasesToMove.ReleaseMetadata !=
NewRetainReleaseRRI.ReleaseMetadata)
ReleasesToMove.ReleaseMetadata = 0;
if (ReleasesToMove.IsTailCallRelease !=
NewRetainReleaseRRI.IsTailCallRelease)
ReleasesToMove.IsTailCallRelease = false;
}
if (!KnownSafe)
for (SmallPtrSet<Instruction *, 2>::const_iterator
RI = NewRetainReleaseRRI.ReverseInsertPts.begin(),
RE = NewRetainReleaseRRI.ReverseInsertPts.end();
RI != RE; ++RI) {
Instruction *RIP = *RI;
if (ReleasesToMove.ReverseInsertPts.insert(RIP)) {
const BBState &RIPBBState = BBStates[RIP->getParent()];
PathCount = BBState::OverflowOccurredValue;
if (RIPBBState.GetAllPathCountWithOverflow(PathCount))
return false;
assert(PathCount != BBState::OverflowOccurredValue &&
"PathCount at this point can not be "
"OverflowOccurredValue.");
NewDelta -= PathCount;
}
}
NewReleases.push_back(NewRetainRelease);
}
}
}
NewRetains.clear();
if (NewReleases.empty()) break;
for (SmallVectorImpl<Instruction *>::const_iterator
NI = NewReleases.begin(), NE = NewReleases.end(); NI != NE; ++NI) {
Instruction *NewRelease = *NI;
DenseMap<Value *, RRInfo>::const_iterator It =
Releases.find(NewRelease);
assert(It != Releases.end());
const RRInfo &NewReleaseRRI = It->second;
KnownSafeBU &= NewReleaseRRI.KnownSafe;
CFGHazardAfflicted |= NewReleaseRRI.CFGHazardAfflicted;
for (SmallPtrSet<Instruction *, 2>::const_iterator
LI = NewReleaseRRI.Calls.begin(),
LE = NewReleaseRRI.Calls.end(); LI != LE; ++LI) {
Instruction *NewReleaseRetain = *LI;
MapVector<Value *, RRInfo>::const_iterator Jt =
Retains.find(NewReleaseRetain);
if (Jt == Retains.end())
return false;
const RRInfo &NewReleaseRetainRRI = Jt->second;
if (!NewReleaseRetainRRI.Calls.count(NewRelease))
return false;
if (RetainsToMove.Calls.insert(NewReleaseRetain)) {
const BBState &NRRBBState = BBStates[NewReleaseRetain->getParent()];
unsigned PathCount = BBState::OverflowOccurredValue;
if (NRRBBState.GetAllPathCountWithOverflow(PathCount))
return false;
assert(PathCount != BBState::OverflowOccurredValue &&
"PathCount at this point can not be "
"OverflowOccurredValue.");
OldDelta += PathCount;
OldCount += PathCount;
if (!KnownSafe)
for (SmallPtrSet<Instruction *, 2>::const_iterator
RI = NewReleaseRetainRRI.ReverseInsertPts.begin(),
RE = NewReleaseRetainRRI.ReverseInsertPts.end();
RI != RE; ++RI) {
Instruction *RIP = *RI;
if (RetainsToMove.ReverseInsertPts.insert(RIP)) {
const BBState &RIPBBState = BBStates[RIP->getParent()];
PathCount = BBState::OverflowOccurredValue;
if (RIPBBState.GetAllPathCountWithOverflow(PathCount))
return false;
assert(PathCount != BBState::OverflowOccurredValue &&
"PathCount at this point can not be "
"OverflowOccurredValue.");
NewDelta += PathCount;
NewCount += PathCount;
}
}
NewRetains.push_back(NewReleaseRetain);
}
}
}
NewReleases.clear();
if (NewRetains.empty()) break;
}
bool UnconditionallySafe = (KnownSafeTD && KnownSafeBU) ||
((KnownSafeTD || KnownSafeBU) && !MultipleOwners);
if (UnconditionallySafe) {
RetainsToMove.ReverseInsertPts.clear();
ReleasesToMove.ReverseInsertPts.clear();
NewCount = 0;
} else {
if (NewDelta != 0)
return false;
const bool WillPerformCodeMotion = RetainsToMove.ReverseInsertPts.size() ||
ReleasesToMove.ReverseInsertPts.size();
if (CFGHazardAfflicted && WillPerformCodeMotion)
return false;
}
if (OldDelta != 0)
return false;
#ifdef ARC_ANNOTATIONS
if (EnableARCAnnotations)
return false;
#endif // ARC_ANNOTATIONS
Changed = true;
assert(OldCount != 0 && "Unreachable code?");
NumRRs += OldCount - NewCount;
AnyPairsCompletelyEliminated = NewCount == 0;
return true;
}
bool
ObjCARCOpt::PerformCodePlacement(DenseMap<const BasicBlock *, BBState>
&BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M) {
DEBUG(dbgs() << "\n== ObjCARCOpt::PerformCodePlacement ==\n");
bool AnyPairsCompletelyEliminated = false;
RRInfo RetainsToMove;
RRInfo ReleasesToMove;
SmallVector<Instruction *, 4> NewRetains;
SmallVector<Instruction *, 4> NewReleases;
SmallVector<Instruction *, 8> DeadInsts;
for (MapVector<Value *, RRInfo>::const_iterator I = Retains.begin(),
E = Retains.end(); I != E; ++I) {
Value *V = I->first;
if (!V) continue;
Instruction *Retain = cast<Instruction>(V);
DEBUG(dbgs() << "Visiting: " << *Retain << "\n");
Value *Arg = GetObjCArg(Retain);
bool KnownSafe = isa<Constant>(Arg) || isa<AllocaInst>(Arg);
if (const LoadInst *LI = dyn_cast<LoadInst>(Arg))
if (const GlobalVariable *GV =
dyn_cast<GlobalVariable>(
StripPointerCastsAndObjCCalls(LI->getPointerOperand())))
if (GV->isConstant())
KnownSafe = true;
NewRetains.push_back(Retain);
bool PerformMoveCalls =
ConnectTDBUTraversals(BBStates, Retains, Releases, M, NewRetains,
NewReleases, DeadInsts, RetainsToMove,
ReleasesToMove, Arg, KnownSafe,
AnyPairsCompletelyEliminated);
if (PerformMoveCalls) {
MoveCalls(Arg, RetainsToMove, ReleasesToMove,
Retains, Releases, DeadInsts, M);
}
NewReleases.clear();
NewRetains.clear();
RetainsToMove.clear();
ReleasesToMove.clear();
}
while (!DeadInsts.empty())
EraseInstruction(DeadInsts.pop_back_val());
return AnyPairsCompletelyEliminated;
}
void ObjCARCOpt::OptimizeWeakCalls(Function &F) {
DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeWeakCalls ==\n");
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
DEBUG(dbgs() << "Visiting: " << *Inst << "\n");
InstructionClass Class = GetBasicInstructionClass(Inst);
if (Class != IC_LoadWeak && Class != IC_LoadWeakRetained)
continue;
if (Class == IC_LoadWeak && Inst->use_empty()) {
Inst->eraseFromParent();
continue;
}
inst_iterator Current = llvm::prior(I);
BasicBlock *CurrentBB = Current.getBasicBlockIterator();
for (BasicBlock::iterator B = CurrentBB->begin(),
J = Current.getInstructionIterator();
J != B; --J) {
Instruction *EarlierInst = &*llvm::prior(J);
InstructionClass EarlierClass = GetInstructionClass(EarlierInst);
switch (EarlierClass) {
case IC_LoadWeak:
case IC_LoadWeakRetained: {
CallInst *Call = cast<CallInst>(Inst);
CallInst *EarlierCall = cast<CallInst>(EarlierInst);
Value *Arg = Call->getArgOperand(0);
Value *EarlierArg = EarlierCall->getArgOperand(0);
switch (PA.getAA()->alias(Arg, EarlierArg)) {
case AliasAnalysis::MustAlias:
Changed = true;
if (Class == IC_LoadWeakRetained) {
Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
CallInst *CI = CallInst::Create(Decl, EarlierCall, "", Call);
CI->setTailCall();
}
Call->replaceAllUsesWith(EarlierCall);
Call->eraseFromParent();
goto clobbered;
case AliasAnalysis::MayAlias:
case AliasAnalysis::PartialAlias:
goto clobbered;
case AliasAnalysis::NoAlias:
break;
}
break;
}
case IC_StoreWeak:
case IC_InitWeak: {
CallInst *Call = cast<CallInst>(Inst);
CallInst *EarlierCall = cast<CallInst>(EarlierInst);
Value *Arg = Call->getArgOperand(0);
Value *EarlierArg = EarlierCall->getArgOperand(0);
switch (PA.getAA()->alias(Arg, EarlierArg)) {
case AliasAnalysis::MustAlias:
Changed = true;
if (Class == IC_LoadWeakRetained) {
Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
CallInst *CI = CallInst::Create(Decl, EarlierCall, "", Call);
CI->setTailCall();
}
Call->replaceAllUsesWith(EarlierCall->getArgOperand(1));
Call->eraseFromParent();
goto clobbered;
case AliasAnalysis::MayAlias:
case AliasAnalysis::PartialAlias:
goto clobbered;
case AliasAnalysis::NoAlias:
break;
}
break;
}
case IC_MoveWeak:
case IC_CopyWeak:
goto clobbered;
case IC_AutoreleasepoolPush:
case IC_None:
case IC_IntrinsicUser:
case IC_User:
break;
default:
goto clobbered;
}
}
clobbered:;
}
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
InstructionClass Class = GetBasicInstructionClass(Inst);
if (Class != IC_DestroyWeak)
continue;
CallInst *Call = cast<CallInst>(Inst);
Value *Arg = Call->getArgOperand(0);
if (AllocaInst *Alloca = dyn_cast<AllocaInst>(Arg)) {
for (Value::use_iterator UI = Alloca->use_begin(),
UE = Alloca->use_end(); UI != UE; ++UI) {
const Instruction *UserInst = cast<Instruction>(*UI);
switch (GetBasicInstructionClass(UserInst)) {
case IC_InitWeak:
case IC_StoreWeak:
case IC_DestroyWeak:
continue;
default:
goto done;
}
}
Changed = true;
for (Value::use_iterator UI = Alloca->use_begin(),
UE = Alloca->use_end(); UI != UE; ) {
CallInst *UserInst = cast<CallInst>(*UI++);
switch (GetBasicInstructionClass(UserInst)) {
case IC_InitWeak:
case IC_StoreWeak:
UserInst->replaceAllUsesWith(UserInst->getArgOperand(1));
break;
case IC_DestroyWeak:
break;
default:
llvm_unreachable("alloca really is used!");
}
UserInst->eraseFromParent();
}
Alloca->eraseFromParent();
done:;
}
}
}
bool ObjCARCOpt::OptimizeSequences(Function &F) {
DenseMap<Value *, RRInfo> Releases;
MapVector<Value *, RRInfo> Retains;
DenseMap<const BasicBlock *, BBState> BBStates;
bool NestingDetected = Visit(F, BBStates, Retains, Releases);
bool AnyPairsCompletelyEliminated = PerformCodePlacement(BBStates, Retains,
Releases,
F.getParent());
MultiOwnersSet.clear();
return AnyPairsCompletelyEliminated && NestingDetected;
}
static bool
HasSafePathToPredecessorCall(const Value *Arg, Instruction *Retain,
SmallPtrSet<Instruction *, 4> &DepInsts,
SmallPtrSet<const BasicBlock *, 4> &Visited,
ProvenanceAnalysis &PA) {
FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
DepInsts, Visited, PA);
if (DepInsts.size() != 1)
return false;
CallInst *Call =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
if (!Call || Arg != Call)
return false;
InstructionClass Class = GetBasicInstructionClass(Call);
if (Class != IC_CallOrUser && Class != IC_Call)
return false;
return true;
}
static CallInst *
FindPredecessorRetainWithSafePath(const Value *Arg, BasicBlock *BB,
Instruction *Autorelease,
SmallPtrSet<Instruction *, 4> &DepInsts,
SmallPtrSet<const BasicBlock *, 4> &Visited,
ProvenanceAnalysis &PA) {
FindDependencies(CanChangeRetainCount, Arg,
BB, Autorelease, DepInsts, Visited, PA);
if (DepInsts.size() != 1)
return 0;
CallInst *Retain =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
if (!Retain ||
!IsRetain(GetBasicInstructionClass(Retain)) ||
GetObjCArg(Retain) != Arg) {
return 0;
}
return Retain;
}
static CallInst *
FindPredecessorAutoreleaseWithSafePath(const Value *Arg, BasicBlock *BB,
ReturnInst *Ret,
SmallPtrSet<Instruction *, 4> &DepInsts,
SmallPtrSet<const BasicBlock *, 4> &V,
ProvenanceAnalysis &PA) {
FindDependencies(NeedsPositiveRetainCount, Arg,
BB, Ret, DepInsts, V, PA);
if (DepInsts.size() != 1)
return 0;
CallInst *Autorelease =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
if (!Autorelease)
return 0;
InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
if (!IsAutorelease(AutoreleaseClass))
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) {
BasicBlock *BB = FI;
ReturnInst *Ret = dyn_cast<ReturnInst>(&BB->back());
DEBUG(dbgs() << "Visiting: " << *Ret << "\n");
if (!Ret)
continue;
const Value *Arg = StripPointerCastsAndObjCCalls(Ret->getOperand(0));
CallInst *Autorelease =
FindPredecessorAutoreleaseWithSafePath(Arg, BB, Ret,
DependingInstructions, Visited,
PA);
DependingInstructions.clear();
Visited.clear();
if (!Autorelease)
continue;
CallInst *Retain =
FindPredecessorRetainWithSafePath(Arg, BB, Autorelease,
DependingInstructions, Visited, PA);
DependingInstructions.clear();
Visited.clear();
if (!Retain)
continue;
bool HasSafePathToCall = HasSafePathToPredecessorCall(Arg, Retain,
DependingInstructions,
Visited, PA);
DependingInstructions.clear();
Visited.clear();
if (!HasSafePathToCall)
continue;
Changed = true;
++NumRets;
DEBUG(dbgs() << "Erasing: " << *Retain << "\nErasing: "
<< *Autorelease << "\n");
EraseInstruction(Retain);
EraseInstruction(Autorelease);
}
}
#ifndef NDEBUG
void
ObjCARCOpt::GatherStatistics(Function &F, bool AfterOptimization) {
llvm::Statistic &NumRetains =
AfterOptimization? NumRetainsAfterOpt : NumRetainsBeforeOpt;
llvm::Statistic &NumReleases =
AfterOptimization? NumReleasesAfterOpt : NumReleasesBeforeOpt;
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
switch (GetBasicInstructionClass(Inst)) {
default:
break;
case IC_Retain:
++NumRetains;
break;
case IC_Release:
++NumReleases;
break;
}
}
}
#endif
bool ObjCARCOpt::doInitialization(Module &M) {
if (!EnableARCOpts)
return false;
Run = ModuleHasARC(M);
if (!Run)
return false;
ImpreciseReleaseMDKind =
M.getContext().getMDKindID("clang.imprecise_release");
CopyOnEscapeMDKind =
M.getContext().getMDKindID("clang.arc.copy_on_escape");
NoObjCARCExceptionsMDKind =
M.getContext().getMDKindID("clang.arc.no_objc_arc_exceptions");
#ifdef ARC_ANNOTATIONS
ARCAnnotationBottomUpMDKind =
M.getContext().getMDKindID("llvm.arc.annotation.bottomup");
ARCAnnotationTopDownMDKind =
M.getContext().getMDKindID("llvm.arc.annotation.topdown");
ARCAnnotationProvenanceSourceMDKind =
M.getContext().getMDKindID("llvm.arc.annotation.provenancesource");
#endif // ARC_ANNOTATIONS
EP.Initialize(&M);
return false;
}
bool ObjCARCOpt::runOnFunction(Function &F) {
if (!EnableARCOpts)
return false;
if (!Run)
return false;
Changed = false;
DEBUG(dbgs() << "<<< ObjCARCOpt: Visiting Function: " << F.getName() << " >>>"
"\n");
PA.setAA(&getAnalysis<AliasAnalysis>());
#ifndef NDEBUG
if (AreStatisticsEnabled()) {
GatherStatistics(F, false);
}
#endif
OptimizeIndividualCalls(F);
if (UsedInThisFunction & ((1 << IC_LoadWeak) |
(1 << IC_LoadWeakRetained) |
(1 << IC_StoreWeak) |
(1 << IC_InitWeak) |
(1 << IC_CopyWeak) |
(1 << IC_MoveWeak) |
(1 << IC_DestroyWeak)))
OptimizeWeakCalls(F);
if (UsedInThisFunction & ((1 << IC_Retain) |
(1 << IC_RetainRV) |
(1 << IC_RetainBlock)))
if (UsedInThisFunction & (1 << IC_Release))
while (OptimizeSequences(F)) {}
if (UsedInThisFunction & ((1 << IC_Autorelease) |
(1 << IC_AutoreleaseRV)))
OptimizeReturns(F);
#ifndef NDEBUG
if (AreStatisticsEnabled()) {
GatherStatistics(F, true);
}
#endif
DEBUG(dbgs() << "\n");
return Changed;
}
void ObjCARCOpt::releaseMemory() {
PA.clear();
}