#define DEBUG_TYPE "objc-arc"
#include "llvm/Function.h"
#include "llvm/Intrinsics.h"
#include "llvm/GlobalVariable.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
static cl::opt<bool> EnableARCOpts("enable-objc-arc-opts", cl::init(true));
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);
}
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();
}
};
}
namespace {
enum InstructionClass {
IC_Retain, IC_RetainRV, IC_RetainBlock, IC_Release, IC_Autorelease, IC_AutoreleaseRV, IC_AutoreleasepoolPush, IC_AutoreleasepoolPop, IC_NoopCast, IC_FusedRetainAutorelease, IC_FusedRetainAutoreleaseRV, IC_LoadWeakRetained, IC_StoreWeak, IC_InitWeak, IC_LoadWeak, IC_MoveWeak, IC_CopyWeak, IC_DestroyWeak, IC_StoreStrong, IC_CallOrUser, IC_Call, IC_User, IC_None };
}
static bool IsPotentialUse(const Value *Op) {
if (isa<Constant>(Op) || isa<AllocaInst>(Op))
return false;
if (const Argument *Arg = dyn_cast<Argument>(Op))
if (Arg->hasByValAttr() ||
Arg->hasNestAttr() ||
Arg->hasStructRetAttr())
return false;
PointerType *Ty = dyn_cast<PointerType>(Op->getType());
if (!Ty)
return false;
return true;
}
static InstructionClass GetCallSiteClass(ImmutableCallSite CS) {
for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
I != E; ++I)
if (IsPotentialUse(*I))
return CS.onlyReadsMemory() ? IC_User : IC_CallOrUser;
return CS.onlyReadsMemory() ? IC_None : IC_Call;
}
static InstructionClass GetFunctionClass(const Function *F) {
Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
if (AI == AE)
return StringSwitch<InstructionClass>(F->getName())
.Case("objc_autoreleasePoolPush", IC_AutoreleasepoolPush)
.Default(IC_CallOrUser);
const Argument *A0 = AI++;
if (AI == AE)
if (PointerType *PTy = dyn_cast<PointerType>(A0->getType())) {
Type *ETy = PTy->getElementType();
if (ETy->isIntegerTy(8))
return StringSwitch<InstructionClass>(F->getName())
.Case("objc_retain", IC_Retain)
.Case("objc_retainAutoreleasedReturnValue", IC_RetainRV)
.Case("objc_retainBlock", IC_RetainBlock)
.Case("objc_release", IC_Release)
.Case("objc_autorelease", IC_Autorelease)
.Case("objc_autoreleaseReturnValue", IC_AutoreleaseRV)
.Case("objc_autoreleasePoolPop", IC_AutoreleasepoolPop)
.Case("objc_retainedObject", IC_NoopCast)
.Case("objc_unretainedObject", IC_NoopCast)
.Case("objc_unretainedPointer", IC_NoopCast)
.Case("objc_retain_autorelease", IC_FusedRetainAutorelease)
.Case("objc_retainAutorelease", IC_FusedRetainAutorelease)
.Case("objc_retainAutoreleaseReturnValue",IC_FusedRetainAutoreleaseRV)
.Default(IC_CallOrUser);
if (PointerType *Pte = dyn_cast<PointerType>(ETy))
if (Pte->getElementType()->isIntegerTy(8))
return StringSwitch<InstructionClass>(F->getName())
.Case("objc_loadWeakRetained", IC_LoadWeakRetained)
.Case("objc_loadWeak", IC_LoadWeak)
.Case("objc_destroyWeak", IC_DestroyWeak)
.Default(IC_CallOrUser);
}
const Argument *A1 = AI++;
if (AI == AE)
if (PointerType *PTy = dyn_cast<PointerType>(A0->getType()))
if (PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType()))
if (Pte->getElementType()->isIntegerTy(8))
if (PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) {
Type *ETy1 = PTy1->getElementType();
if (ETy1->isIntegerTy(8))
return StringSwitch<InstructionClass>(F->getName())
.Case("objc_storeWeak", IC_StoreWeak)
.Case("objc_initWeak", IC_InitWeak)
.Case("objc_storeStrong", IC_StoreStrong)
.Default(IC_CallOrUser);
if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1))
if (Pte1->getElementType()->isIntegerTy(8))
return StringSwitch<InstructionClass>(F->getName())
.Case("objc_moveWeak", IC_MoveWeak)
.Case("objc_copyWeak", IC_CopyWeak)
.Default(IC_CallOrUser);
}
return IC_CallOrUser;
}
static InstructionClass GetInstructionClass(const Value *V) {
if (const Instruction *I = dyn_cast<Instruction>(V)) {
switch (I->getOpcode()) {
case Instruction::Call: {
const CallInst *CI = cast<CallInst>(I);
if (const Function *F = CI->getCalledFunction()) {
InstructionClass Class = GetFunctionClass(F);
if (Class != IC_CallOrUser)
return Class;
switch (F->getIntrinsicID()) {
case 0: break;
case Intrinsic::bswap: case Intrinsic::ctpop:
case Intrinsic::ctlz: case Intrinsic::cttz:
case Intrinsic::returnaddress: case Intrinsic::frameaddress:
case Intrinsic::stacksave: case Intrinsic::stackrestore:
case Intrinsic::vastart: case Intrinsic::vacopy: case Intrinsic::vaend:
case Intrinsic::dbg_declare: case Intrinsic::dbg_value:
return IC_None;
default:
for (Function::const_arg_iterator AI = F->arg_begin(),
AE = F->arg_end(); AI != AE; ++AI)
if (IsPotentialUse(AI))
return IC_User;
return IC_None;
}
}
return GetCallSiteClass(CI);
}
case Instruction::Invoke:
return GetCallSiteClass(cast<InvokeInst>(I));
case Instruction::BitCast:
case Instruction::GetElementPtr:
case Instruction::Select: case Instruction::PHI:
case Instruction::Ret: case Instruction::Br:
case Instruction::Switch: case Instruction::IndirectBr:
case Instruction::Alloca: case Instruction::VAArg:
case Instruction::Add: case Instruction::FAdd:
case Instruction::Sub: case Instruction::FSub:
case Instruction::Mul: case Instruction::FMul:
case Instruction::SDiv: case Instruction::UDiv: case Instruction::FDiv:
case Instruction::SRem: case Instruction::URem: case Instruction::FRem:
case Instruction::Shl: case Instruction::LShr: case Instruction::AShr:
case Instruction::And: case Instruction::Or: case Instruction::Xor:
case Instruction::SExt: case Instruction::ZExt: case Instruction::Trunc:
case Instruction::IntToPtr: case Instruction::FCmp:
case Instruction::FPTrunc: case Instruction::FPExt:
case Instruction::FPToUI: case Instruction::FPToSI:
case Instruction::UIToFP: case Instruction::SIToFP:
case Instruction::InsertElement: case Instruction::ExtractElement:
case Instruction::ShuffleVector:
case Instruction::ExtractValue:
break;
case Instruction::ICmp:
if (IsPotentialUse(I->getOperand(1)))
return IC_User;
break;
default:
for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end();
OI != OE; ++OI)
if (IsPotentialUse(*OI))
return IC_User;
}
}
return IC_None;
}
static InstructionClass GetBasicInstructionClass(const Value *V) {
if (const CallInst *CI = dyn_cast<CallInst>(V)) {
if (const Function *F = CI->getCalledFunction())
return GetFunctionClass(F);
return IC_CallOrUser;
}
return isa<InvokeInst>(V) ? IC_CallOrUser : IC_User;
}
static bool IsRetain(InstructionClass Class) {
return Class == IC_Retain ||
Class == IC_RetainRV;
}
static bool IsAutorelease(InstructionClass Class) {
return Class == IC_Autorelease ||
Class == IC_AutoreleaseRV;
}
static bool IsForwarding(InstructionClass Class) {
return Class == IC_Retain ||
Class == IC_RetainRV ||
Class == IC_Autorelease ||
Class == IC_AutoreleaseRV ||
Class == IC_RetainBlock ||
Class == IC_NoopCast;
}
static bool IsNoopOnNull(InstructionClass Class) {
return Class == IC_Retain ||
Class == IC_RetainRV ||
Class == IC_Release ||
Class == IC_Autorelease ||
Class == IC_AutoreleaseRV ||
Class == IC_RetainBlock;
}
static bool IsAlwaysTail(InstructionClass Class) {
return Class == IC_Retain ||
Class == IC_RetainRV ||
Class == IC_Autorelease ||
Class == IC_AutoreleaseRV;
}
static bool IsNoThrow(InstructionClass Class) {
return Class == IC_Retain ||
Class == IC_RetainRV ||
Class == IC_Release ||
Class == IC_Autorelease ||
Class == IC_AutoreleaseRV ||
Class == IC_AutoreleasepoolPush ||
Class == IC_AutoreleasepoolPop;
}
static void EraseInstruction(Instruction *CI) {
Value *OldArg = cast<CallInst>(CI)->getArgOperand(0);
bool Unused = CI->use_empty();
if (!Unused) {
assert(IsForwarding(GetBasicInstructionClass(CI)) &&
"Can't delete non-forwarding instruction with users!");
CI->replaceAllUsesWith(OldArg);
}
CI->eraseFromParent();
if (Unused)
RecursivelyDeleteTriviallyDeadInstructions(OldArg);
}
static const Value *GetUnderlyingObjCPtr(const Value *V) {
for (;;) {
V = GetUnderlyingObject(V);
if (!IsForwarding(GetBasicInstructionClass(V)))
break;
V = cast<CallInst>(V)->getArgOperand(0);
}
return V;
}
static const Value *StripPointerCastsAndObjCCalls(const Value *V) {
for (;;) {
V = V->stripPointerCasts();
if (!IsForwarding(GetBasicInstructionClass(V)))
break;
V = cast<CallInst>(V)->getArgOperand(0);
}
return V;
}
static Value *StripPointerCastsAndObjCCalls(Value *V) {
for (;;) {
V = V->stripPointerCasts();
if (!IsForwarding(GetBasicInstructionClass(V)))
break;
V = cast<CallInst>(V)->getArgOperand(0);
}
return V;
}
static Value *GetObjCArg(Value *Inst) {
return StripPointerCastsAndObjCCalls(cast<CallInst>(Inst)->getArgOperand(0));
}
static bool IsObjCIdentifiedObject(const Value *V) {
if (isa<CallInst>(V) || isa<InvokeInst>(V) ||
isa<Argument>(V) || isa<Constant>(V) ||
isa<AllocaInst>(V))
return true;
if (const LoadInst *LI = dyn_cast<LoadInst>(V)) {
const Value *Pointer =
StripPointerCastsAndObjCCalls(LI->getPointerOperand());
if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Pointer)) {
if (GV->isConstant())
return true;
StringRef Name = GV->getName();
if (Name.startswith("\01L_OBJC_SELECTOR_REFERENCES_") ||
Name.startswith("\01L_OBJC_CLASSLIST_REFERENCES_") ||
Name.startswith("\01L_OBJC_CLASSLIST_SUP_REFS_$_") ||
Name.startswith("\01L_OBJC_METH_VAR_NAME_") ||
Name.startswith("\01l_objc_msgSend_fixup_"))
return true;
}
}
return false;
}
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 bool ModuleHasARC(const Module &M) {
return
M.getNamedValue("objc_retain") ||
M.getNamedValue("objc_release") ||
M.getNamedValue("objc_autorelease") ||
M.getNamedValue("objc_retainAutoreleasedReturnValue") ||
M.getNamedValue("objc_retainBlock") ||
M.getNamedValue("objc_autoreleaseReturnValue") ||
M.getNamedValue("objc_autoreleasePoolPush") ||
M.getNamedValue("objc_loadWeakRetained") ||
M.getNamedValue("objc_loadWeak") ||
M.getNamedValue("objc_destroyWeak") ||
M.getNamedValue("objc_storeWeak") ||
M.getNamedValue("objc_initWeak") ||
M.getNamedValue("objc_moveWeak") ||
M.getNamedValue("objc_copyWeak") ||
M.getNamedValue("objc_retainedObject") ||
M.getNamedValue("objc_unretainedObject") ||
M.getNamedValue("objc_unretainedPointer");
}
static bool DoesObjCBlockEscape(const Value *BlockPtr) {
SmallVector<const Value *, 4> Worklist;
Worklist.push_back(BlockPtr);
do {
const Value *V = Worklist.pop_back_val();
for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
const User *UUser = *UI;
switch (GetBasicInstructionClass(UUser)) {
case IC_StoreWeak:
case IC_InitWeak:
case IC_StoreStrong:
case IC_Autorelease:
case IC_AutoreleaseRV:
return true;
case IC_User:
case IC_None:
if (isa<BitCastInst>(UUser) || isa<GetElementPtrInst>(UUser) ||
isa<PHINode>(UUser) || isa<SelectInst>(UUser)) {
Worklist.push_back(UUser);
continue;
}
if (isa<LoadInst>(UUser))
continue;
if (const StoreInst *SI = dyn_cast<StoreInst>(UUser))
if (V != SI->getValueOperand())
continue;
break;
default:
continue;
}
return true;
}
} while (!Worklist.empty());
return false;
}
#include "llvm/Pass.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/Passes.h"
namespace {
class ObjCARCAliasAnalysis : public ImmutablePass,
public AliasAnalysis {
public:
static char ID; ObjCARCAliasAnalysis() : ImmutablePass(ID) {
initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry());
}
private:
virtual void initializePass() {
InitializeAliasAnalysis(this);
}
virtual void *getAdjustedAnalysisPointer(const void *PI) {
if (PI == &AliasAnalysis::ID)
return (AliasAnalysis*)this;
return this;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual AliasResult alias(const Location &LocA, const Location &LocB);
virtual bool pointsToConstantMemory(const Location &Loc, bool OrLocal);
virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
virtual ModRefBehavior getModRefBehavior(const Function *F);
virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
const Location &Loc);
virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
ImmutableCallSite CS2);
};
}
char ObjCARCAliasAnalysis::ID = 0;
INITIALIZE_AG_PASS(ObjCARCAliasAnalysis, AliasAnalysis, "objc-arc-aa",
"ObjC-ARC-Based Alias Analysis", false, true, false)
ImmutablePass *llvm::createObjCARCAliasAnalysisPass() {
return new ObjCARCAliasAnalysis();
}
void
ObjCARCAliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AliasAnalysis::getAnalysisUsage(AU);
}
AliasAnalysis::AliasResult
ObjCARCAliasAnalysis::alias(const Location &LocA, const Location &LocB) {
if (!EnableARCOpts)
return AliasAnalysis::alias(LocA, LocB);
const Value *SA = StripPointerCastsAndObjCCalls(LocA.Ptr);
const Value *SB = StripPointerCastsAndObjCCalls(LocB.Ptr);
AliasResult Result =
AliasAnalysis::alias(Location(SA, LocA.Size, LocA.TBAATag),
Location(SB, LocB.Size, LocB.TBAATag));
if (Result != MayAlias)
return Result;
const Value *UA = GetUnderlyingObjCPtr(SA);
const Value *UB = GetUnderlyingObjCPtr(SB);
if (UA != SA || UB != SB) {
Result = AliasAnalysis::alias(Location(UA), Location(UB));
if (Result == NoAlias)
return NoAlias;
}
return MayAlias;
}
bool
ObjCARCAliasAnalysis::pointsToConstantMemory(const Location &Loc,
bool OrLocal) {
if (!EnableARCOpts)
return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
const Value *S = StripPointerCastsAndObjCCalls(Loc.Ptr);
if (AliasAnalysis::pointsToConstantMemory(Location(S, Loc.Size, Loc.TBAATag),
OrLocal))
return true;
const Value *U = GetUnderlyingObjCPtr(S);
if (U != S)
return AliasAnalysis::pointsToConstantMemory(Location(U), OrLocal);
return false;
}
AliasAnalysis::ModRefBehavior
ObjCARCAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
return AliasAnalysis::getModRefBehavior(CS);
}
AliasAnalysis::ModRefBehavior
ObjCARCAliasAnalysis::getModRefBehavior(const Function *F) {
if (!EnableARCOpts)
return AliasAnalysis::getModRefBehavior(F);
switch (GetFunctionClass(F)) {
case IC_NoopCast:
return DoesNotAccessMemory;
default:
break;
}
return AliasAnalysis::getModRefBehavior(F);
}
AliasAnalysis::ModRefResult
ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS, const Location &Loc) {
if (!EnableARCOpts)
return AliasAnalysis::getModRefInfo(CS, Loc);
switch (GetBasicInstructionClass(CS.getInstruction())) {
case IC_Retain:
case IC_RetainRV:
case IC_Autorelease:
case IC_AutoreleaseRV:
case IC_NoopCast:
case IC_AutoreleasepoolPush:
case IC_FusedRetainAutorelease:
case IC_FusedRetainAutoreleaseRV:
return NoModRef;
default:
break;
}
return AliasAnalysis::getModRefInfo(CS, Loc);
}
AliasAnalysis::ModRefResult
ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS1,
ImmutableCallSite CS2) {
return AliasAnalysis::getModRefInfo(CS1, CS2);
}
#include "llvm/Support/InstIterator.h"
#include "llvm/Transforms/Scalar.h"
namespace {
class ObjCARCExpand : public FunctionPass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual bool doInitialization(Module &M);
virtual bool runOnFunction(Function &F);
bool Run;
public:
static char ID;
ObjCARCExpand() : FunctionPass(ID) {
initializeObjCARCExpandPass(*PassRegistry::getPassRegistry());
}
};
}
char ObjCARCExpand::ID = 0;
INITIALIZE_PASS(ObjCARCExpand,
"objc-arc-expand", "ObjC ARC expansion", false, false)
Pass *llvm::createObjCARCExpandPass() {
return new ObjCARCExpand();
}
void ObjCARCExpand::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
}
bool ObjCARCExpand::doInitialization(Module &M) {
Run = ModuleHasARC(M);
return false;
}
bool ObjCARCExpand::runOnFunction(Function &F) {
if (!EnableARCOpts)
return false;
if (!Run)
return false;
bool Changed = false;
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ++I) {
Instruction *Inst = &*I;
switch (GetBasicInstructionClass(Inst)) {
case IC_Retain:
case IC_RetainRV:
case IC_Autorelease:
case IC_AutoreleaseRV:
case IC_FusedRetainAutorelease:
case IC_FusedRetainAutoreleaseRV:
Changed = true;
Inst->replaceAllUsesWith(cast<CallInst>(Inst)->getArgOperand(0));
break;
default:
break;
}
}
return Changed;
}
#include "llvm/Constants.h"
namespace {
class ObjCARCAPElim : public ModulePass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual bool runOnModule(Module &M);
bool MayAutorelease(CallSite CS, unsigned Depth = 0);
bool OptimizeBB(BasicBlock *BB);
public:
static char ID;
ObjCARCAPElim() : ModulePass(ID) {
initializeObjCARCAPElimPass(*PassRegistry::getPassRegistry());
}
};
}
char ObjCARCAPElim::ID = 0;
INITIALIZE_PASS(ObjCARCAPElim,
"objc-arc-apelim",
"ObjC ARC autorelease pool elimination",
false, false)
Pass *llvm::createObjCARCAPElimPass() {
return new ObjCARCAPElim();
}
void ObjCARCAPElim::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
}
bool ObjCARCAPElim::MayAutorelease(CallSite CS, unsigned Depth) {
if (Function *Callee = CS.getCalledFunction()) {
if (Callee->isDeclaration() || Callee->mayBeOverridden())
return true;
for (Function::iterator I = Callee->begin(), E = Callee->end();
I != E; ++I) {
BasicBlock *BB = I;
for (BasicBlock::iterator J = BB->begin(), F = BB->end(); J != F; ++J)
if (CallSite JCS = CallSite(J))
if (Depth < 3 &&
!JCS.onlyReadsMemory() &&
MayAutorelease(JCS, Depth + 1))
return true;
}
return false;
}
return true;
}
bool ObjCARCAPElim::OptimizeBB(BasicBlock *BB) {
bool Changed = false;
Instruction *Push = 0;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
Instruction *Inst = I++;
switch (GetBasicInstructionClass(Inst)) {
case IC_AutoreleasepoolPush:
Push = Inst;
break;
case IC_AutoreleasepoolPop:
if (Push && cast<CallInst>(Inst)->getArgOperand(0) == Push) {
Changed = true;
Inst->eraseFromParent();
Push->eraseFromParent();
}
Push = 0;
break;
case IC_CallOrUser:
if (MayAutorelease(CallSite(Inst)))
Push = 0;
break;
default:
break;
}
}
return Changed;
}
bool ObjCARCAPElim::runOnModule(Module &M) {
if (!EnableARCOpts)
return false;
if (!ModuleHasARC(M))
return false;
GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
if (!GV)
return false;
assert(GV->hasDefinitiveInitializer() &&
"llvm.global_ctors is uncooperative!");
bool Changed = false;
ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
for (User::op_iterator OI = Init->op_begin(), OE = Init->op_end();
OI != OE; ++OI) {
Value *Op = *OI;
Function *F = dyn_cast<Function>(cast<ConstantStruct>(Op)->getOperand(1));
if (!F)
continue;
if (F->isDeclaration())
continue;
if (llvm::next(F->begin()) != F->end())
continue;
Changed |= OptimizeBB(F->begin());
}
return Changed;
}
#include "llvm/GlobalAlias.h"
#include "llvm/Constants.h"
#include "llvm/LLVMContext.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/CFG.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/DenseSet.h"
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+autoreleaes eliminated");
STATISTIC(NumRRs, "Number of retain+release paths eliminated");
STATISTIC(NumPeeps, "Number of calls peephole-optimized");
namespace {
class ProvenanceAnalysis {
AliasAnalysis *AA;
typedef std::pair<const Value *, const Value *> ValuePairTy;
typedef DenseMap<ValuePairTy, bool> CachedResultsTy;
CachedResultsTy CachedResults;
bool relatedCheck(const Value *A, const Value *B);
bool relatedSelect(const SelectInst *A, const Value *B);
bool relatedPHI(const PHINode *A, const Value *B);
void operator=(const ProvenanceAnalysis &);
ProvenanceAnalysis(const ProvenanceAnalysis &);
public:
ProvenanceAnalysis() {}
void setAA(AliasAnalysis *aa) { AA = aa; }
AliasAnalysis *getAA() const { return AA; }
bool related(const Value *A, const Value *B);
void clear() {
CachedResults.clear();
}
};
}
bool ProvenanceAnalysis::relatedSelect(const SelectInst *A, const Value *B) {
if (const SelectInst *SB = dyn_cast<SelectInst>(B))
if (A->getCondition() == SB->getCondition()) {
if (related(A->getTrueValue(), SB->getTrueValue()))
return true;
if (related(A->getFalseValue(), SB->getFalseValue()))
return true;
return false;
}
if (related(A->getTrueValue(), B))
return true;
if (related(A->getFalseValue(), B))
return true;
return false;
}
bool ProvenanceAnalysis::relatedPHI(const PHINode *A, const Value *B) {
if (const PHINode *PNB = dyn_cast<PHINode>(B))
if (PNB->getParent() == A->getParent()) {
for (unsigned i = 0, e = A->getNumIncomingValues(); i != e; ++i)
if (related(A->getIncomingValue(i),
PNB->getIncomingValueForBlock(A->getIncomingBlock(i))))
return true;
return false;
}
SmallPtrSet<const Value *, 4> UniqueSrc;
for (unsigned i = 0, e = A->getNumIncomingValues(); i != e; ++i) {
const Value *PV1 = A->getIncomingValue(i);
if (UniqueSrc.insert(PV1) && related(PV1, B))
return true;
}
return false;
}
static bool isStoredObjCPointer(const Value *P) {
SmallPtrSet<const Value *, 8> Visited;
SmallVector<const Value *, 8> Worklist;
Worklist.push_back(P);
Visited.insert(P);
do {
P = Worklist.pop_back_val();
for (Value::const_use_iterator UI = P->use_begin(), UE = P->use_end();
UI != UE; ++UI) {
const User *Ur = *UI;
if (isa<StoreInst>(Ur)) {
if (UI.getOperandNo() == 0)
return true;
continue;
}
if (isa<CallInst>(Ur))
continue;
if (isa<PtrToIntInst>(P))
return true;
if (Visited.insert(Ur))
Worklist.push_back(Ur);
}
} while (!Worklist.empty());
return false;
}
bool ProvenanceAnalysis::relatedCheck(const Value *A, const Value *B) {
A = GetUnderlyingObjCPtr(A);
B = GetUnderlyingObjCPtr(B);
if (A == B)
return true;
switch (AA->alias(A, B)) {
case AliasAnalysis::NoAlias:
return false;
case AliasAnalysis::MustAlias:
case AliasAnalysis::PartialAlias:
return true;
case AliasAnalysis::MayAlias:
break;
}
bool AIsIdentified = IsObjCIdentifiedObject(A);
bool BIsIdentified = IsObjCIdentifiedObject(B);
if (AIsIdentified) {
if (BIsIdentified) {
if (A != B)
return false;
} else {
if (isa<LoadInst>(B))
return isStoredObjCPointer(A);
}
} else {
if (BIsIdentified && isa<LoadInst>(A))
return isStoredObjCPointer(B);
}
if (const PHINode *PN = dyn_cast<PHINode>(A))
return relatedPHI(PN, B);
if (const PHINode *PN = dyn_cast<PHINode>(B))
return relatedPHI(PN, A);
if (const SelectInst *S = dyn_cast<SelectInst>(A))
return relatedSelect(S, B);
if (const SelectInst *S = dyn_cast<SelectInst>(B))
return relatedSelect(S, A);
return true;
}
bool ProvenanceAnalysis::related(const Value *A, const Value *B) {
if (A > B) std::swap(A, B);
std::pair<CachedResultsTy::iterator, bool> Pair =
CachedResults.insert(std::make_pair(ValuePairTy(A, B), true));
if (!Pair.second)
return Pair.first->second;
bool Result = relatedCheck(A, B);
CachedResults[ValuePairTy(A, B)] = Result;
return Result;
}
namespace {
enum Sequence {
S_None,
S_Retain, S_CanRelease, S_Use, S_Stop, S_Release, S_MovableRelease };
}
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 IsRetainBlock;
bool IsTailCallRelease;
bool Partial;
MDNode *ReleaseMetadata;
SmallPtrSet<Instruction *, 2> Calls;
SmallPtrSet<Instruction *, 2> ReverseInsertPts;
RRInfo() :
KnownSafe(false), IsRetainBlock(false),
IsTailCallRelease(false), Partial(false),
ReleaseMetadata(0) {}
void clear();
};
}
void RRInfo::clear() {
KnownSafe = false;
IsRetainBlock = false;
IsTailCallRelease = false;
Partial = false;
ReleaseMetadata = 0;
Calls.clear();
ReverseInsertPts.clear();
}
namespace {
class PtrState {
unsigned RefCount;
unsigned NestCount;
Sequence Seq;
public:
RRInfo RRI;
PtrState() : RefCount(0), NestCount(0), Seq(S_None) {}
void SetAtLeastOneRefCount() {
if (RefCount == 0) RefCount = 1;
}
void IncrementRefCount() {
if (RefCount != UINT_MAX) ++RefCount;
}
void DecrementRefCount() {
if (RefCount != 0) --RefCount;
}
bool IsKnownIncremented() const {
return RefCount > 0;
}
void IncrementNestCount() {
if (NestCount != UINT_MAX) ++NestCount;
}
void DecrementNestCount() {
if (NestCount != 0) --NestCount;
}
bool IsKnownNested() const {
return NestCount > 0;
}
void SetSeq(Sequence NewSeq) {
Seq = NewSeq;
}
Sequence GetSeq() const {
return Seq;
}
void ClearSequenceProgress() {
Seq = S_None;
RRI.clear();
}
void Merge(const PtrState &Other, bool TopDown);
};
}
void
PtrState::Merge(const PtrState &Other, bool TopDown) {
Seq = MergeSeqs(Seq, Other.Seq, TopDown);
RefCount = std::min(RefCount, Other.RefCount);
NestCount = std::min(NestCount, Other.NestCount);
if (RRI.IsRetainBlock != Other.RRI.IsRetainBlock)
Seq = S_None;
if (Seq == S_None) {
RRI.clear();
} else if (RRI.Partial || Other.RRI.Partial) {
Seq = S_None;
RRI.clear();
} else {
if (RRI.ReleaseMetadata != Other.RRI.ReleaseMetadata)
RRI.ReleaseMetadata = 0;
RRI.KnownSafe = RRI.KnownSafe && Other.RRI.KnownSafe;
RRI.IsTailCallRelease = RRI.IsTailCallRelease && Other.RRI.IsTailCallRelease;
RRI.Calls.insert(Other.RRI.Calls.begin(), Other.RRI.Calls.end());
RRI.Partial = RRI.ReverseInsertPts.size() !=
Other.RRI.ReverseInsertPts.size();
for (SmallPtrSet<Instruction *, 2>::const_iterator
I = Other.RRI.ReverseInsertPts.begin(),
E = Other.RRI.ReverseInsertPts.end(); I != E; ++I)
RRI.Partial |= RRI.ReverseInsertPts.insert(*I);
}
}
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:
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];
}
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);
unsigned GetAllPathCount() const {
assert(TopDownPathCount != 0);
assert(BottomUpPathCount != 0);
return TopDownPathCount * BottomUpPathCount;
}
typedef SmallVectorImpl<BasicBlock *>::iterator edge_iterator;
edge_iterator pred_begin() { return Preds.begin(); }
edge_iterator pred_end() { return Preds.end(); }
edge_iterator succ_begin() { return Succs.begin(); }
edge_iterator succ_end() { 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(); }
};
}
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) {
TopDownPathCount += Other.TopDownPathCount;
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) {
BottomUpPathCount += Other.BottomUpPathCount;
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);
}
namespace {
class ObjCARCOpt : public FunctionPass {
bool Changed;
ProvenanceAnalysis PA;
bool Run;
Constant *RetainRVCallee, *AutoreleaseRVCallee, *ReleaseCallee,
*RetainCallee, *RetainBlockCallee, *AutoreleaseCallee;
unsigned UsedInThisFunction;
unsigned ImpreciseReleaseMDKind;
unsigned CopyOnEscapeMDKind;
unsigned NoObjCARCExceptionsMDKind;
Constant *getRetainRVCallee(Module *M);
Constant *getAutoreleaseRVCallee(Module *M);
Constant *getReleaseCallee(Module *M);
Constant *getRetainCallee(Module *M);
Constant *getRetainBlockCallee(Module *M);
Constant *getAutoreleaseCallee(Module *M);
bool IsRetainBlockOptimizable(const Instruction *Inst);
void OptimizeRetainCall(Function &F, Instruction *Retain);
bool OptimizeRetainRVCall(Function &F, Instruction *RetainRV);
void OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV);
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 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);
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::IsRetainBlockOptimizable(const Instruction *Inst) {
if (!Inst->getMetadata(CopyOnEscapeMDKind))
return false;
if (DoesObjCBlockEscape(Inst))
return false;
return true;
}
Constant *ObjCARCOpt::getRetainRVCallee(Module *M) {
if (!RetainRVCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
std::vector<Type *> Params;
Params.push_back(I8X);
FunctionType *FTy =
FunctionType::get(I8X, Params, false);
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
RetainRVCallee =
M->getOrInsertFunction("objc_retainAutoreleasedReturnValue", FTy,
Attributes);
}
return RetainRVCallee;
}
Constant *ObjCARCOpt::getAutoreleaseRVCallee(Module *M) {
if (!AutoreleaseRVCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
std::vector<Type *> Params;
Params.push_back(I8X);
FunctionType *FTy =
FunctionType::get(I8X, Params, false);
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
AutoreleaseRVCallee =
M->getOrInsertFunction("objc_autoreleaseReturnValue", FTy,
Attributes);
}
return AutoreleaseRVCallee;
}
Constant *ObjCARCOpt::getReleaseCallee(Module *M) {
if (!ReleaseCallee) {
LLVMContext &C = M->getContext();
std::vector<Type *> Params;
Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
ReleaseCallee =
M->getOrInsertFunction(
"objc_release",
FunctionType::get(Type::getVoidTy(C), Params, false),
Attributes);
}
return ReleaseCallee;
}
Constant *ObjCARCOpt::getRetainCallee(Module *M) {
if (!RetainCallee) {
LLVMContext &C = M->getContext();
std::vector<Type *> Params;
Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
RetainCallee =
M->getOrInsertFunction(
"objc_retain",
FunctionType::get(Params[0], Params, false),
Attributes);
}
return RetainCallee;
}
Constant *ObjCARCOpt::getRetainBlockCallee(Module *M) {
if (!RetainBlockCallee) {
LLVMContext &C = M->getContext();
std::vector<Type *> Params;
Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
AttrListPtr Attributes;
RetainBlockCallee =
M->getOrInsertFunction(
"objc_retainBlock",
FunctionType::get(Params[0], Params, false),
Attributes);
}
return RetainBlockCallee;
}
Constant *ObjCARCOpt::getAutoreleaseCallee(Module *M) {
if (!AutoreleaseCallee) {
LLVMContext &C = M->getContext();
std::vector<Type *> Params;
Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
AutoreleaseCallee =
M->getOrInsertFunction(
"objc_autorelease",
FunctionType::get(Params[0], Params, false),
Attributes);
}
return AutoreleaseCallee;
}
static bool
CanAlterRefCount(const Instruction *Inst, const Value *Ptr,
ProvenanceAnalysis &PA, InstructionClass Class) {
switch (Class) {
case IC_Autorelease:
case IC_AutoreleaseRV:
case IC_User:
return false;
default: break;
}
ImmutableCallSite CS = static_cast<const Value *>(Inst);
assert(CS && "Only calls can alter reference counts!");
AliasAnalysis::ModRefBehavior MRB = PA.getAA()->getModRefBehavior(CS);
if (AliasAnalysis::onlyReadsMemory(MRB))
return false;
if (AliasAnalysis::onlyAccessesArgPointees(MRB)) {
for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
I != E; ++I) {
const Value *Op = *I;
if (IsPotentialUse(Op) && PA.related(Ptr, Op))
return true;
}
return false;
}
return true;
}
static bool
CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA,
InstructionClass Class) {
if (Class == IC_Call)
return false;
if (const ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
if (!IsPotentialUse(ICI->getOperand(1)))
return false;
} else if (ImmutableCallSite CS = static_cast<const Value *>(Inst)) {
for (ImmutableCallSite::arg_iterator OI = CS.arg_begin(),
OE = CS.arg_end(); OI != OE; ++OI) {
const Value *Op = *OI;
if (IsPotentialUse(Op) && PA.related(Ptr, Op))
return true;
}
return false;
} else if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
const Value *Op = GetUnderlyingObjCPtr(SI->getPointerOperand());
return IsPotentialUse(Op) && PA.related(Op, Ptr);
}
for (User::const_op_iterator OI = Inst->op_begin(), OE = Inst->op_end();
OI != OE; ++OI) {
const Value *Op = *OI;
if (IsPotentialUse(Op) && PA.related(Ptr, Op))
return true;
}
return false;
}
static bool
CanInterruptRV(InstructionClass Class) {
switch (Class) {
case IC_AutoreleasepoolPop:
case IC_CallOrUser:
case IC_Call:
case IC_Autorelease:
case IC_AutoreleaseRV:
case IC_FusedRetainAutorelease:
case IC_FusedRetainAutoreleaseRV:
return true;
default:
return false;
}
}
namespace {
enum DependenceKind {
NeedsPositiveRetainCount,
AutoreleasePoolBoundary,
CanChangeRetainCount,
RetainAutoreleaseDep, RetainAutoreleaseRVDep, RetainRVDep };
}
static bool
Depends(DependenceKind Flavor, Instruction *Inst, const Value *Arg,
ProvenanceAnalysis &PA) {
if (Inst == Arg)
return true;
switch (Flavor) {
case NeedsPositiveRetainCount: {
InstructionClass Class = GetInstructionClass(Inst);
switch (Class) {
case IC_AutoreleasepoolPop:
case IC_AutoreleasepoolPush:
case IC_None:
return false;
default:
return CanUse(Inst, Arg, PA, Class);
}
}
case AutoreleasePoolBoundary: {
InstructionClass Class = GetInstructionClass(Inst);
switch (Class) {
case IC_AutoreleasepoolPop:
case IC_AutoreleasepoolPush:
return true;
default:
return false;
}
}
case CanChangeRetainCount: {
InstructionClass Class = GetInstructionClass(Inst);
switch (Class) {
case IC_AutoreleasepoolPop:
return true;
case IC_AutoreleasepoolPush:
case IC_None:
return false;
default:
return CanAlterRefCount(Inst, Arg, PA, Class);
}
}
case RetainAutoreleaseDep:
switch (GetBasicInstructionClass(Inst)) {
case IC_AutoreleasepoolPop:
case IC_AutoreleasepoolPush:
return true;
case IC_Retain:
case IC_RetainRV:
return GetObjCArg(Inst) == Arg;
default:
return false;
}
case RetainAutoreleaseRVDep: {
InstructionClass Class = GetBasicInstructionClass(Inst);
switch (Class) {
case IC_Retain:
case IC_RetainRV:
return GetObjCArg(Inst) == Arg;
default:
return CanInterruptRV(Class);
}
}
case RetainRVDep:
return CanInterruptRV(GetBasicInstructionClass(Inst));
}
llvm_unreachable("Invalid dependence flavor");
}
static void
FindDependencies(DependenceKind Flavor,
const Value *Arg,
BasicBlock *StartBB, Instruction *StartInst,
SmallPtrSet<Instruction *, 4> &DependingInstructions,
SmallPtrSet<const BasicBlock *, 4> &Visited,
ProvenanceAnalysis &PA) {
BasicBlock::iterator StartPos = StartInst;
SmallVector<std::pair<BasicBlock *, BasicBlock::iterator>, 4> Worklist;
Worklist.push_back(std::make_pair(StartBB, StartPos));
do {
std::pair<BasicBlock *, BasicBlock::iterator> Pair =
Worklist.pop_back_val();
BasicBlock *LocalStartBB = Pair.first;
BasicBlock::iterator LocalStartPos = Pair.second;
BasicBlock::iterator StartBBBegin = LocalStartBB->begin();
for (;;) {
if (LocalStartPos == StartBBBegin) {
pred_iterator PI(LocalStartBB), PE(LocalStartBB, false);
if (PI == PE)
DependingInstructions.insert(0);
else
do {
BasicBlock *PredBB = *PI;
if (Visited.insert(PredBB))
Worklist.push_back(std::make_pair(PredBB, PredBB->end()));
} while (++PI != PE);
break;
}
Instruction *Inst = --LocalStartPos;
if (Depends(Flavor, Inst, Arg, PA)) {
DependingInstructions.insert(Inst);
break;
}
}
} while (!Worklist.empty());
for (SmallPtrSet<const BasicBlock *, 4>::const_iterator I = Visited.begin(),
E = Visited.end(); I != E; ++I) {
const BasicBlock *BB = *I;
if (BB == StartBB)
continue;
const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
for (succ_const_iterator SI(TI), SE(TI, false); SI != SE; ++SI) {
const BasicBlock *Succ = *SI;
if (Succ != StartBB && !Visited.count(Succ)) {
DependingInstructions.insert(reinterpret_cast<Instruction *>(-1));
return;
}
}
}
}
static bool isNullOrUndef(const Value *V) {
return isa<ConstantPointerNull>(V) || isa<UndefValue>(V);
}
static bool isNoopInstruction(const Instruction *I) {
return isa<BitCastInst>(I) ||
(isa<GetElementPtrInst>(I) &&
cast<GetElementPtrInst>(I)->hasAllZeroIndices());
}
void
ObjCARCOpt::OptimizeRetainCall(Function &F, Instruction *Retain) {
CallSite CS(GetObjCArg(Retain));
Instruction *Call = CS.getInstruction();
if (!Call) return;
if (Call->getParent() != Retain->getParent()) return;
BasicBlock::iterator I = Call;
++I;
while (isNoopInstruction(I)) ++I;
if (&*I != Retain)
return;
Changed = true;
++NumPeeps;
cast<CallInst>(Retain)->setCalledFunction(getRetainRVCallee(F.getParent()));
}
bool
ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
Value *Arg = GetObjCArg(RetainRV);
CallSite CS(Arg);
if (Instruction *Call = CS.getInstruction())
if (Call->getParent() == RetainRV->getParent()) {
BasicBlock::iterator I = Call;
++I;
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;
EraseInstruction(I);
EraseInstruction(RetainRV);
return true;
}
}
Changed = true;
++NumPeeps;
cast<CallInst>(RetainRV)->setCalledFunction(getRetainCallee(F.getParent()));
return false;
}
void
ObjCARCOpt::OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV) {
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;
cast<CallInst>(AutoreleaseRV)->
setCalledFunction(getAutoreleaseCallee(F.getParent()));
}
void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
UsedInThisFunction = 0;
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
InstructionClass Class = GetBasicInstructionClass(Inst);
switch (Class) {
default: break;
case IC_NoopCast:
Changed = true;
++NumNoops;
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))) {
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
Constant::getNullValue(Ty),
CI);
CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
CI->eraseFromParent();
continue;
}
break;
}
case IC_CopyWeak:
case IC_MoveWeak: {
CallInst *CI = cast<CallInst>(Inst);
if (isNullOrUndef(CI->getArgOperand(0)) ||
isNullOrUndef(CI->getArgOperand(1))) {
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
Constant::getNullValue(Ty),
CI);
CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
CI->eraseFromParent();
continue;
}
break;
}
case IC_Retain:
OptimizeRetainCall(F, Inst);
break;
case IC_RetainRV:
if (OptimizeRetainRVCall(F, Inst))
continue;
break;
case IC_AutoreleaseRV:
OptimizeAutoreleaseRVCall(F, Inst);
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();
CallInst *NewCall =
CallInst::Create(getReleaseCallee(F.getParent()),
Call->getArgOperand(0), "", Call);
NewCall->setMetadata(ImpreciseReleaseMDKind,
MDNode::get(C, ArrayRef<Value *>()));
EraseInstruction(Call);
Inst = NewCall;
Class = IC_Release;
}
}
if (IsAlwaysTail(Class)) {
Changed = true;
cast<CallInst>(Inst)->setTailCall();
}
if (IsNoThrow(Class)) {
Changed = true;
cast<CallInst>(Inst)->setDoesNotThrow();
}
if (!IsNoopOnNull(Class)) {
UsedInThisFunction |= 1 << Class;
continue;
}
const Value *Arg = GetObjCArg(Inst);
if (isNullOrUndef(Arg)) {
Changed = true;
++NumNoops;
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);
Worklist.push_back(std::make_pair(Clone, Incoming));
}
}
EraseInstruction(CInst);
continue;
}
}
} while (!Worklist.empty());
}
}
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)
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);
if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind))
--SE;
for (; SI != SE; ++SI) {
Sequence SuccSSeq = S_None;
bool SuccSRRIKnownSafe = false;
DenseMap<const BasicBlock *, BBState>::iterator BBI = BBStates.find(*SI);
if (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 (SomeSuccHasSame && !AllSuccsHaveSame)
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);
if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind))
--SE;
for (; SI != SE; ++SI) {
Sequence SuccSSeq = S_None;
bool SuccSRRIKnownSafe = false;
DenseMap<const BasicBlock *, BBState>::iterator BBI = BBStates.find(*SI);
if (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;
}
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!");
}
}
if (SomeSuccHasSame && !AllSuccsHaveSame)
S.ClearSequenceProgress();
break;
}
}
}
bool
ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst,
BasicBlock *BB,
MapVector<Value *, RRInfo> &Retains,
BBState &MyStates) {
bool NestingDetected = false;
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
switch (Class) {
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
if (S.GetSeq() == S_Release || S.GetSeq() == S_MovableRelease)
NestingDetected = true;
S.RRI.clear();
MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
S.SetSeq(ReleaseMetadata ? S_MovableRelease : S_Release);
S.RRI.ReleaseMetadata = ReleaseMetadata;
S.RRI.KnownSafe = S.IsKnownNested() || S.IsKnownIncremented();
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
S.RRI.Calls.insert(Inst);
S.IncrementRefCount();
S.IncrementNestCount();
break;
}
case IC_RetainBlock:
if (!IsRetainBlockOptimizable(Inst))
break;
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
S.DecrementRefCount();
S.SetAtLeastOneRefCount();
S.DecrementNestCount();
switch (S.GetSeq()) {
case S_Stop:
case S_Release:
case S_MovableRelease:
case S_Use:
S.RRI.ReverseInsertPts.clear();
case S_CanRelease:
if (Class != IC_RetainRV) {
S.RRI.IsRetainBlock = Class == IC_RetainBlock;
Retains[Inst] = S.RRI;
}
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
return NestingDetected;
}
case IC_AutoreleasepoolPop:
MyStates.clearBottomUpPointers();
return NestingDetected;
case IC_AutoreleasepoolPush:
case IC_None:
return NestingDetected;
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)) {
S.DecrementRefCount();
switch (Seq) {
case S_Use:
S.SetSeq(S_CanRelease);
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)) {
assert(S.RRI.ReverseInsertPts.empty());
if (isa<InvokeInst>(Inst))
S.RRI.ReverseInsertPts.insert(BB->getFirstInsertionPt());
else
S.RRI.ReverseInsertPts.insert(next(BasicBlock::iterator(Inst)));
S.SetSeq(S_Use);
} else if (Seq == S_Release &&
(Class == IC_User || Class == IC_CallOrUser)) {
S.SetSeq(S_Stop);
assert(S.RRI.ReverseInsertPts.empty());
if (isa<InvokeInst>(Inst))
S.RRI.ReverseInsertPts.insert(BB->getFirstInsertionPt());
else
S.RRI.ReverseInsertPts.insert(next(BasicBlock::iterator(Inst)));
}
break;
case S_Stop:
if (CanUse(Inst, Ptr, PA, Class))
S.SetSeq(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) {
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
for (BBState::edge_iterator SI(MyStates.succ_begin()),
SE(MyStates.succ_end()); SI != SE; ++SI) {
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);
}
break;
}
for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; --I) {
Instruction *Inst = llvm::prior(I);
if (isa<InvokeInst>(Inst))
continue;
NestingDetected |= VisitInstructionBottomUp(Inst, BB, Retains, MyStates);
}
for (BBState::edge_iterator PI(MyStates.pred_begin()),
PE(MyStates.pred_end()); PI != PE; ++PI) {
BasicBlock *Pred = *PI;
TerminatorInst *PredTI = cast<TerminatorInst>(&Pred->back());
if (isa<InvokeInst>(PredTI))
NestingDetected |= VisitInstructionBottomUp(PredTI, BB, Retains, MyStates);
}
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:
if (!IsRetainBlockOptimizable(Inst))
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;
S.SetSeq(S_Retain);
S.RRI.clear();
S.RRI.IsRetainBlock = Class == IC_RetainBlock;
S.RRI.KnownSafe = S.IsKnownNested();
S.RRI.Calls.insert(Inst);
}
S.SetAtLeastOneRefCount();
S.IncrementRefCount();
S.IncrementNestCount();
break;
}
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
S.DecrementRefCount();
S.DecrementNestCount();
switch (S.GetSeq()) {
case S_Retain:
case S_CanRelease:
S.RRI.ReverseInsertPts.clear();
case S_Use:
S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
Releases[Inst] = S.RRI;
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)) {
S.DecrementRefCount();
switch (Seq) {
case S_Retain:
S.SetSeq(S_CanRelease);
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(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))
S.SetSeq(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) {
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
for (BBState::edge_iterator PI(MyStates.pred_begin()),
PE(MyStates.pred_end()); PI != PE; ++PI) {
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);
}
break;
}
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
Instruction *Inst = I;
NestingDetected |= VisitInstructionTopDown(Inst, Releases, MyStates);
}
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();
BBStates[EntryBB].SetAsEntry();
SuccStack.push_back(std::make_pair(EntryBB, succ_begin(EntryBB)));
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);
if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind))
--SE;
while (SuccStack.back().second != SE) {
BasicBlock *SuccBB = *SuccStack.back().second++;
if (Visited.insert(SuccBB)) {
SuccStack.push_back(std::make_pair(SuccBB, succ_begin(SuccBB)));
BBStates[CurrBB].addSucc(SuccBB);
BBStates[SuccBB].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;
BBStates[ExitBB].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()));
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);
CallInst *Call =
CallInst::Create(RetainsToMove.IsRetainBlock ?
getRetainBlockCallee(M) : getRetainCallee(M),
MyArg, "", InsertPt);
Call->setDoesNotThrow();
if (RetainsToMove.IsRetainBlock)
Call->setMetadata(CopyOnEscapeMDKind,
MDNode::get(M->getContext(), ArrayRef<Value *>()));
else
Call->setTailCall();
}
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);
CallInst *Call = CallInst::Create(getReleaseCallee(M), MyArg,
"", InsertPt);
if (MDNode *M = ReleasesToMove.ReleaseMetadata)
Call->setMetadata(ImpreciseReleaseMDKind, M);
Call->setDoesNotThrow();
if (ReleasesToMove.IsTailCallRelease)
Call->setTailCall();
}
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);
}
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);
}
}
bool
ObjCARCOpt::PerformCodePlacement(DenseMap<const BasicBlock *, BBState>
&BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M) {
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);
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;
bool KnownSafeTD = true, KnownSafeBU = true;
unsigned OldDelta = 0;
unsigned NewDelta = 0;
unsigned OldCount = 0;
unsigned NewCount = 0;
bool FirstRelease = true;
bool FirstRetain = true;
NewRetains.push_back(Retain);
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;
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())
goto next_retain;
const RRInfo &NewRetainReleaseRRI = Jt->second;
assert(NewRetainReleaseRRI.Calls.count(NewRetain));
if (ReleasesToMove.Calls.insert(NewRetainRelease)) {
OldDelta -=
BBStates[NewRetainRelease->getParent()].GetAllPathCount();
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))
NewDelta -= BBStates[RIP->getParent()].GetAllPathCount();
}
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;
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())
goto next_retain;
const RRInfo &NewReleaseRetainRRI = Jt->second;
assert(NewReleaseRetainRRI.Calls.count(NewRelease));
if (RetainsToMove.Calls.insert(NewReleaseRetain)) {
unsigned PathCount =
BBStates[NewReleaseRetain->getParent()].GetAllPathCount();
OldDelta += PathCount;
OldCount += PathCount;
if (FirstRetain) {
RetainsToMove.IsRetainBlock = NewReleaseRetainRRI.IsRetainBlock;
FirstRetain = false;
} else if (ReleasesToMove.IsRetainBlock !=
NewReleaseRetainRRI.IsRetainBlock)
goto next_retain;
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)) {
PathCount = BBStates[RIP->getParent()].GetAllPathCount();
NewDelta += PathCount;
NewCount += PathCount;
}
}
NewRetains.push_back(NewReleaseRetain);
}
}
}
NewReleases.clear();
if (NewRetains.empty()) break;
}
if (KnownSafeTD || KnownSafeBU) {
RetainsToMove.ReverseInsertPts.clear();
ReleasesToMove.ReverseInsertPts.clear();
NewCount = 0;
} else {
if (NewDelta != 0)
goto next_retain;
}
if (OldDelta != 0)
goto next_retain;
Changed = true;
assert(OldCount != 0 && "Unreachable code?");
AnyPairsCompletelyEliminated = NewCount == 0;
NumRRs += OldCount - NewCount;
MoveCalls(Arg, RetainsToMove, ReleasesToMove,
Retains, Releases, DeadInsts, M);
next_retain:
NewReleases.clear();
NewRetains.clear();
RetainsToMove.clear();
ReleasesToMove.clear();
}
while (!DeadInsts.empty())
EraseInstruction(DeadInsts.pop_back_val());
return AnyPairsCompletelyEliminated;
}
void ObjCARCOpt::OptimizeWeakCalls(Function &F) {
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
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) {
CallInst *CI =
CallInst::Create(getRetainCallee(F.getParent()), 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) {
CallInst *CI =
CallInst::Create(getRetainCallee(F.getParent()), 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_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) {
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:
break;
}
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);
return PerformCodePlacement(BBStates, Retains, Releases, F.getParent()) &&
NestingDetected;
}
void ObjCARCOpt::OptimizeReturns(Function &F) {
if (!F.getReturnType()->isPointerTy())
return;
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());
if (!Ret) continue;
const Value *Arg = StripPointerCastsAndObjCCalls(Ret->getOperand(0));
FindDependencies(NeedsPositiveRetainCount, Arg,
BB, Ret, DependingInstructions, Visited, PA);
if (DependingInstructions.size() != 1)
goto next_block;
{
CallInst *Autorelease =
dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
if (!Autorelease)
goto next_block;
InstructionClass AutoreleaseClass =
GetBasicInstructionClass(Autorelease);
if (!IsAutorelease(AutoreleaseClass))
goto next_block;
if (GetObjCArg(Autorelease) != Arg)
goto next_block;
DependingInstructions.clear();
Visited.clear();
FindDependencies(CanChangeRetainCount, Arg,
BB, Autorelease, DependingInstructions, Visited, PA);
if (DependingInstructions.size() != 1)
goto next_block;
{
CallInst *Retain =
dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
if (!Retain ||
!IsRetain(GetBasicInstructionClass(Retain)) ||
GetObjCArg(Retain) != Arg)
goto next_block;
DependingInstructions.clear();
Visited.clear();
if (AutoreleaseClass == IC_Autorelease) {
Autorelease->setCalledFunction(getAutoreleaseRVCallee(F.getParent()));
AutoreleaseClass = IC_AutoreleaseRV;
}
FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
DependingInstructions, Visited, PA);
if (DependingInstructions.size() != 1)
goto next_block;
{
CallInst *Call =
dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
if (!Call || Arg != Call)
goto next_block;
InstructionClass Class = GetBasicInstructionClass(Call);
if (Class != IC_CallOrUser && Class != IC_Call)
goto next_block;
Changed = true;
++NumRets;
EraseInstruction(Retain);
EraseInstruction(Autorelease);
}
}
}
next_block:
DependingInstructions.clear();
Visited.clear();
}
}
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");
RetainRVCallee = 0;
AutoreleaseRVCallee = 0;
ReleaseCallee = 0;
RetainCallee = 0;
RetainBlockCallee = 0;
AutoreleaseCallee = 0;
return false;
}
bool ObjCARCOpt::runOnFunction(Function &F) {
if (!EnableARCOpts)
return false;
if (!Run)
return false;
Changed = false;
PA.setAA(&getAnalysis<AliasAnalysis>());
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);
return Changed;
}
void ObjCARCOpt::releaseMemory() {
PA.clear();
}
#include "llvm/Operator.h"
#include "llvm/InlineAsm.h"
#include "llvm/Analysis/Dominators.h"
STATISTIC(NumStoreStrongs, "Number objc_storeStrong calls formed");
namespace {
class ObjCARCContract : public FunctionPass {
bool Changed;
AliasAnalysis *AA;
DominatorTree *DT;
ProvenanceAnalysis PA;
bool Run;
Constant *StoreStrongCallee,
*RetainAutoreleaseCallee, *RetainAutoreleaseRVCallee;
const MDString *RetainRVMarker;
DenseSet<CallInst *> StoreStrongCalls;
Constant *getStoreStrongCallee(Module *M);
Constant *getRetainAutoreleaseCallee(Module *M);
Constant *getRetainAutoreleaseRVCallee(Module *M);
bool ContractAutorelease(Function &F, Instruction *Autorelease,
InstructionClass Class,
SmallPtrSet<Instruction *, 4>
&DependingInstructions,
SmallPtrSet<const BasicBlock *, 4>
&Visited);
void ContractRelease(Instruction *Release,
inst_iterator &Iter);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual bool doInitialization(Module &M);
virtual bool runOnFunction(Function &F);
public:
static char ID;
ObjCARCContract() : FunctionPass(ID) {
initializeObjCARCContractPass(*PassRegistry::getPassRegistry());
}
};
}
char ObjCARCContract::ID = 0;
INITIALIZE_PASS_BEGIN(ObjCARCContract,
"objc-arc-contract", "ObjC ARC contraction", false, false)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
INITIALIZE_PASS_END(ObjCARCContract,
"objc-arc-contract", "ObjC ARC contraction", false, false)
Pass *llvm::createObjCARCContractPass() {
return new ObjCARCContract();
}
void ObjCARCContract::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<AliasAnalysis>();
AU.addRequired<DominatorTree>();
AU.setPreservesCFG();
}
Constant *ObjCARCContract::getStoreStrongCallee(Module *M) {
if (!StoreStrongCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
Type *I8XX = PointerType::getUnqual(I8X);
std::vector<Type *> Params;
Params.push_back(I8XX);
Params.push_back(I8X);
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
Attributes.addAttr(1, Attribute::NoCapture);
StoreStrongCallee =
M->getOrInsertFunction(
"objc_storeStrong",
FunctionType::get(Type::getVoidTy(C), Params, false),
Attributes);
}
return StoreStrongCallee;
}
Constant *ObjCARCContract::getRetainAutoreleaseCallee(Module *M) {
if (!RetainAutoreleaseCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
std::vector<Type *> Params;
Params.push_back(I8X);
FunctionType *FTy =
FunctionType::get(I8X, Params, false);
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
RetainAutoreleaseCallee =
M->getOrInsertFunction("objc_retainAutorelease", FTy, Attributes);
}
return RetainAutoreleaseCallee;
}
Constant *ObjCARCContract::getRetainAutoreleaseRVCallee(Module *M) {
if (!RetainAutoreleaseRVCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
std::vector<Type *> Params;
Params.push_back(I8X);
FunctionType *FTy =
FunctionType::get(I8X, Params, false);
AttrListPtr Attributes;
Attributes.addAttr(~0u, Attribute::NoUnwind);
RetainAutoreleaseRVCallee =
M->getOrInsertFunction("objc_retainAutoreleaseReturnValue", FTy,
Attributes);
}
return RetainAutoreleaseRVCallee;
}
bool
ObjCARCContract::ContractAutorelease(Function &F, Instruction *Autorelease,
InstructionClass Class,
SmallPtrSet<Instruction *, 4>
&DependingInstructions,
SmallPtrSet<const BasicBlock *, 4>
&Visited) {
const Value *Arg = GetObjCArg(Autorelease);
CallInst *Retain = 0;
if (Class == IC_AutoreleaseRV)
FindDependencies(RetainAutoreleaseRVDep, Arg,
Autorelease->getParent(), Autorelease,
DependingInstructions, Visited, PA);
else
FindDependencies(RetainAutoreleaseDep, Arg,
Autorelease->getParent(), Autorelease,
DependingInstructions, Visited, PA);
Visited.clear();
if (DependingInstructions.size() != 1) {
DependingInstructions.clear();
return false;
}
Retain = dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
DependingInstructions.clear();
if (!Retain ||
GetBasicInstructionClass(Retain) != IC_Retain ||
GetObjCArg(Retain) != Arg)
return false;
Changed = true;
++NumPeeps;
if (Class == IC_AutoreleaseRV)
Retain->setCalledFunction(getRetainAutoreleaseRVCallee(F.getParent()));
else
Retain->setCalledFunction(getRetainAutoreleaseCallee(F.getParent()));
EraseInstruction(Autorelease);
return true;
}
void ObjCARCContract::ContractRelease(Instruction *Release,
inst_iterator &Iter) {
LoadInst *Load = dyn_cast<LoadInst>(GetObjCArg(Release));
if (!Load || !Load->isSimple()) return;
BasicBlock *BB = Release->getParent();
if (Load->getParent() != BB) return;
BasicBlock::iterator I = Load, End = BB->end();
++I;
AliasAnalysis::Location Loc = AA->getLocation(Load);
StoreInst *Store = 0;
bool SawRelease = false;
for (; !Store || !SawRelease; ++I) {
if (I == End)
return;
Instruction *Inst = I;
if (Inst == Release) {
SawRelease = true;
continue;
}
InstructionClass Class = GetBasicInstructionClass(Inst);
if (IsRetain(Class))
continue;
if (Store) {
if (CanUse(Inst, Load, PA, Class))
return;
} else if (AA->getModRefInfo(Inst, Loc) & AliasAnalysis::Mod) {
Store = dyn_cast<StoreInst>(Inst);
if (!Store || !Store->isSimple()) return;
if (Store->getPointerOperand() != Loc.Ptr) return;
}
}
Value *New = StripPointerCastsAndObjCCalls(Store->getValueOperand());
I = Store;
BasicBlock::iterator Begin = BB->begin();
while (I != Begin && GetBasicInstructionClass(I) != IC_Retain)
--I;
Instruction *Retain = I;
if (GetBasicInstructionClass(Retain) != IC_Retain) return;
if (GetObjCArg(Retain) != New) return;
Changed = true;
++NumStoreStrongs;
LLVMContext &C = Release->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
Type *I8XX = PointerType::getUnqual(I8X);
Value *Args[] = { Load->getPointerOperand(), New };
if (Args[0]->getType() != I8XX)
Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
if (Args[1]->getType() != I8X)
Args[1] = new BitCastInst(Args[1], I8X, "", Store);
CallInst *StoreStrong =
CallInst::Create(getStoreStrongCallee(BB->getParent()->getParent()),
Args, "", Store);
StoreStrong->setDoesNotThrow();
StoreStrong->setDebugLoc(Store->getDebugLoc());
StoreStrongCalls.insert(StoreStrong);
if (&*Iter == Store) ++Iter;
Store->eraseFromParent();
Release->eraseFromParent();
EraseInstruction(Retain);
if (Load->use_empty())
Load->eraseFromParent();
}
bool ObjCARCContract::doInitialization(Module &M) {
Run = ModuleHasARC(M);
if (!Run)
return false;
StoreStrongCallee = 0;
RetainAutoreleaseCallee = 0;
RetainAutoreleaseRVCallee = 0;
RetainRVMarker = 0;
if (NamedMDNode *NMD =
M.getNamedMetadata("clang.arc.retainAutoreleasedReturnValueMarker"))
if (NMD->getNumOperands() == 1) {
const MDNode *N = NMD->getOperand(0);
if (N->getNumOperands() == 1)
if (const MDString *S = dyn_cast<MDString>(N->getOperand(0)))
RetainRVMarker = S;
}
return false;
}
bool ObjCARCContract::runOnFunction(Function &F) {
if (!EnableARCOpts)
return false;
if (!Run)
return false;
Changed = false;
AA = &getAnalysis<AliasAnalysis>();
DT = &getAnalysis<DominatorTree>();
PA.setAA(&getAnalysis<AliasAnalysis>());
bool TailOkForStoreStrongs = !F.isVarArg() && !F.callsFunctionThatReturnsTwice();
SmallPtrSet<Instruction *, 4> DependingInstructions;
SmallPtrSet<const BasicBlock *, 4> Visited;
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
InstructionClass Class = GetBasicInstructionClass(Inst);
switch (Class) {
case IC_Retain:
case IC_FusedRetainAutorelease:
case IC_FusedRetainAutoreleaseRV:
break;
case IC_Autorelease:
case IC_AutoreleaseRV:
if (ContractAutorelease(F, Inst, Class, DependingInstructions, Visited))
continue;
break;
case IC_RetainRV: {
if (!RetainRVMarker)
break;
BasicBlock::iterator BBI = Inst;
BasicBlock *InstParent = Inst->getParent();
do {
if (&*BBI == InstParent->begin()) {
BasicBlock *Pred = InstParent->getSinglePredecessor();
if (!Pred)
goto decline_rv_optimization;
BBI = Pred->getTerminator();
break;
}
--BBI;
} while (isNoopInstruction(BBI));
if (&*BBI == GetObjCArg(Inst)) {
InlineAsm *IA =
InlineAsm::get(FunctionType::get(Type::getVoidTy(Inst->getContext()),
false),
RetainRVMarker->getString(),
"", true);
CallInst::Create(IA, "", Inst);
}
decline_rv_optimization:
break;
}
case IC_InitWeak: {
CallInst *CI = cast<CallInst>(Inst);
if (isNullOrUndef(CI->getArgOperand(1))) {
Value *Null =
ConstantPointerNull::get(cast<PointerType>(CI->getType()));
Changed = true;
new StoreInst(Null, CI->getArgOperand(0), CI);
CI->replaceAllUsesWith(Null);
CI->eraseFromParent();
}
continue;
}
case IC_Release:
ContractRelease(Inst, I);
continue;
case IC_User:
if (isa<AllocaInst>(Inst))
TailOkForStoreStrongs = false;
continue;
default:
continue;
}
const Value *Arg = cast<CallInst>(Inst)->getArgOperand(0);
for (;;) {
if (!isa<Instruction>(Arg) && !isa<Argument>(Arg))
break;
for (Value::const_use_iterator UI = Arg->use_begin(), UE = Arg->use_end();
UI != UE; ) {
Use &U = UI.getUse();
unsigned OperandNo = UI.getOperandNo();
++UI; Instruction *UserInst = dyn_cast<Instruction>(U.getUser());
if (!UserInst)
continue;
if (DT->isReachableFromEntry(UserInst->getParent()) &&
DT->dominates(Inst, UserInst)) {
Changed = true;
Instruction *Replacement = Inst;
Type *UseTy = U.get()->getType();
if (PHINode *PHI = dyn_cast<PHINode>(UserInst)) {
unsigned ValNo =
PHINode::getIncomingValueNumForOperand(OperandNo);
BasicBlock *BB =
PHI->getIncomingBlock(ValNo);
if (Replacement->getType() != UseTy)
Replacement = new BitCastInst(Replacement, UseTy, "",
&BB->back());
for (unsigned i = 0, e = PHI->getNumIncomingValues();
i != e; ++i)
if (PHI->getIncomingBlock(i) == BB) {
if (&PHI->getOperandUse(
PHINode::getOperandNumForIncomingValue(i)) ==
&UI.getUse())
++UI;
PHI->setIncomingValue(i, Replacement);
}
} else {
if (Replacement->getType() != UseTy)
Replacement = new BitCastInst(Replacement, UseTy, "", UserInst);
U.set(Replacement);
}
}
}
if (const BitCastInst *BI = dyn_cast<BitCastInst>(Arg))
Arg = BI->getOperand(0);
else if (isa<GEPOperator>(Arg) &&
cast<GEPOperator>(Arg)->hasAllZeroIndices())
Arg = cast<GEPOperator>(Arg)->getPointerOperand();
else if (isa<GlobalAlias>(Arg) &&
!cast<GlobalAlias>(Arg)->mayBeOverridden())
Arg = cast<GlobalAlias>(Arg)->getAliasee();
else
break;
}
}
if (TailOkForStoreStrongs)
for (DenseSet<CallInst *>::iterator I = StoreStrongCalls.begin(),
E = StoreStrongCalls.end(); I != E; ++I)
(*I)->setTailCall();
StoreStrongCalls.clear();
return Changed;
}