GS.StoredType = GlobalStatus::isStored;
}
}
+ } else if (isa<BitCastInst>(I)) {
+ if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
} else if (isa<GetElementPtrInst>(I)) {
if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
} else if (isa<SelectInst>(I)) {
return false;
}
+/// isLeakCheckerRoot - Is this global variable possibly used by a leak checker
+/// as a root? If so, we might not really want to eliminate the stores to it.
+static bool isLeakCheckerRoot(GlobalVariable *GV) {
+ // A global variable is a root if it is a pointer, or could plausibly contain
+ // a pointer. There are two challenges; one is that we could have a struct
+ // the has an inner member which is a pointer. We recurse through the type to
+ // detect these (up to a point). The other is that we may actually be a union
+ // of a pointer and another type, and so our LLVM type is an integer which
+ // gets converted into a pointer, or our type is an [i8 x #] with a pointer
+ // potentially contained here.
+
+ if (GV->hasPrivateLinkage())
+ return false;
+
+ SmallVector<Type *, 4> Types;
+ Types.push_back(cast<PointerType>(GV->getType())->getElementType());
+
+ unsigned Limit = 20;
+ do {
+ Type *Ty = Types.pop_back_val();
+ switch (Ty->getTypeID()) {
+ default: break;
+ case Type::PointerTyID: return true;
+ case Type::ArrayTyID:
+ case Type::VectorTyID: {
+ SequentialType *STy = cast<SequentialType>(Ty);
+ Types.push_back(STy->getElementType());
+ break;
+ }
+ case Type::StructTyID: {
+ StructType *STy = cast<StructType>(Ty);
+ if (STy->isOpaque()) return true;
+ for (StructType::element_iterator I = STy->element_begin(),
+ E = STy->element_end(); I != E; ++I) {
+ Type *InnerTy = *I;
+ if (isa<PointerType>(InnerTy)) return true;
+ if (isa<CompositeType>(InnerTy))
+ Types.push_back(InnerTy);
+ }
+ break;
+ }
+ }
+ if (--Limit == 0) return true;
+ } while (!Types.empty());
+ return false;
+}
+
+/// Given a value that is stored to a global but never read, determine whether
+/// it's safe to remove the store and the chain of computation that feeds the
+/// store.
+static bool IsSafeComputationToRemove(Value *V, const TargetLibraryInfo *TLI) {
+ do {
+ if (isa<Constant>(V))
+ return true;
+ if (!V->hasOneUse())
+ return false;
+ if (isa<LoadInst>(V) || isa<InvokeInst>(V) || isa<Argument>(V) ||
+ isa<GlobalValue>(V))
+ return false;
+ if (isAllocationFn(V, TLI))
+ return true;
+
+ Instruction *I = cast<Instruction>(V);
+ if (I->mayHaveSideEffects())
+ return false;
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
+ if (!GEP->hasAllConstantIndices())
+ return false;
+ } else if (I->getNumOperands() != 1) {
+ return false;
+ }
+
+ V = I->getOperand(0);
+ } while (1);
+}
+
+/// CleanupPointerRootUsers - This GV is a pointer root. Loop over all users
+/// of the global and clean up any that obviously don't assign the global a
+/// value that isn't dynamically allocated.
+///
+static bool CleanupPointerRootUsers(GlobalVariable *GV,
+ const TargetLibraryInfo *TLI) {
+ // A brief explanation of leak checkers. The goal is to find bugs where
+ // pointers are forgotten, causing an accumulating growth in memory
+ // usage over time. The common strategy for leak checkers is to whitelist the
+ // memory pointed to by globals at exit. This is popular because it also
+ // solves another problem where the main thread of a C++ program may shut down
+ // before other threads that are still expecting to use those globals. To
+ // handle that case, we expect the program may create a singleton and never
+ // destroy it.
+
+ bool Changed = false;
+
+ // If Dead[n].first is the only use of a malloc result, we can delete its
+ // chain of computation and the store to the global in Dead[n].second.
+ SmallVector<std::pair<Instruction *, Instruction *>, 32> Dead;
+
+ // Constants can't be pointers to dynamically allocated memory.
+ for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end();
+ UI != E;) {
+ User *U = *UI++;
+ if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+ Value *V = SI->getValueOperand();
+ if (isa<Constant>(V)) {
+ Changed = true;
+ SI->eraseFromParent();
+ } else if (Instruction *I = dyn_cast<Instruction>(V)) {
+ if (I->hasOneUse())
+ Dead.push_back(std::make_pair(I, SI));
+ }
+ } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(U)) {
+ if (isa<Constant>(MSI->getValue())) {
+ Changed = true;
+ MSI->eraseFromParent();
+ } else if (Instruction *I = dyn_cast<Instruction>(MSI->getValue())) {
+ if (I->hasOneUse())
+ Dead.push_back(std::make_pair(I, MSI));
+ }
+ } else if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U)) {
+ GlobalVariable *MemSrc = dyn_cast<GlobalVariable>(MTI->getSource());
+ if (MemSrc && MemSrc->isConstant()) {
+ Changed = true;
+ MTI->eraseFromParent();
+ } else if (Instruction *I = dyn_cast<Instruction>(MemSrc)) {
+ if (I->hasOneUse())
+ Dead.push_back(std::make_pair(I, MTI));
+ }
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
+ if (CE->use_empty()) {
+ CE->destroyConstant();
+ Changed = true;
+ }
+ } else if (Constant *C = dyn_cast<Constant>(U)) {
+ if (SafeToDestroyConstant(C)) {
+ C->destroyConstant();
+ // This could have invalidated UI, start over from scratch.
+ Dead.clear();
+ CleanupPointerRootUsers(GV, TLI);
+ return true;
+ }
+ }
+ }
+
+ for (int i = 0, e = Dead.size(); i != e; ++i) {
+ if (IsSafeComputationToRemove(Dead[i].first, TLI)) {
+ Dead[i].second->eraseFromParent();
+ Instruction *I = Dead[i].first;
+ do {
+ if (isAllocationFn(I, TLI))
+ break;
+ Instruction *J = dyn_cast<Instruction>(I->getOperand(0));
+ if (!J)
+ break;
+ I->eraseFromParent();
+ I = J;
+ } while (1);
+ I->eraseFromParent();
+ }
+ }
+
+ return Changed;
+}
+
/// CleanupConstantGlobalUsers - We just marked GV constant. Loop over all
/// users of the global, cleaning up the obvious ones. This is largely just a
/// quick scan over the use list to clean up the easy and obvious cruft. This
GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false,
GlobalVariable::InternalLinkage,
In, GV->getName()+"."+Twine(i),
- GV->isThreadLocal(),
+ GV->getThreadLocalMode(),
GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
GlobalVariable *NGV = new GlobalVariable(STy->getElementType(), false,
GlobalVariable::InternalLinkage,
In, GV->getName()+"."+Twine(i),
- GV->isThreadLocal(),
+ GV->getThreadLocalMode(),
GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
// If we get here we could have other crazy uses that are transitively
// loaded.
assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
- isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser)) &&
+ isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser) ||
+ isa<BitCastInst>(GlobalUser) ||
+ isa<GetElementPtrInst>(GlobalUser)) &&
"Only expect load and stores!");
}
}
// If we nuked all of the loads, then none of the stores are needed either,
// nor is the global.
if (AllNonStoreUsesGone) {
- DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
- CleanupConstantGlobalUsers(GV, 0, TD, TLI);
+ if (isLeakCheckerRoot(GV)) {
+ Changed |= CleanupPointerRootUsers(GV, TLI);
+ } else {
+ Changed = true;
+ CleanupConstantGlobalUsers(GV, 0, TD, TLI);
+ }
if (GV->use_empty()) {
+ DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
+ Changed = true;
GV->eraseFromParent();
++NumDeleted;
}
- Changed = true;
}
return Changed;
}
UndefValue::get(GlobalType),
GV->getName()+".body",
GV,
- GV->isThreadLocal());
+ GV->getThreadLocalMode());
// If there are bitcast users of the malloc (which is typical, usually we have
// a malloc + bitcast) then replace them with uses of the new global. Update
new GlobalVariable(Type::getInt1Ty(GV->getContext()), false,
GlobalValue::InternalLinkage,
ConstantInt::getFalse(GV->getContext()),
- GV->getName()+".init", GV->isThreadLocal());
+ GV->getName()+".init", GV->getThreadLocalMode());
bool InitBoolUsed = false;
// Loop over all uses of GV, processing them in turn.
/// PerformHeapAllocSRoA - CI is an allocation of an array of structures. Break
/// it up into multiple allocations of arrays of the fields.
static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI,
- Value *NElems, TargetData *TD) {
+ Value *NElems, TargetData *TD,
+ const TargetLibraryInfo *TLI) {
DEBUG(dbgs() << "SROA HEAP ALLOC: " << *GV << " MALLOC = " << *CI << '\n');
- Type *MAT = getMallocAllocatedType(CI);
+ Type *MAT = getMallocAllocatedType(CI, TLI);
StructType *STy = cast<StructType>(MAT);
// There is guaranteed to be at least one use of the malloc (storing
PFieldTy, false, GlobalValue::InternalLinkage,
Constant::getNullValue(PFieldTy),
GV->getName() + ".f" + Twine(FieldNo), GV,
- GV->isThreadLocal());
+ GV->getThreadLocalMode());
FieldGlobals.push_back(NGV);
unsigned TypeSize = TD->getTypeAllocSize(FieldTy);
// This eliminates dynamic allocation, avoids an indirection accessing the
// data, and exposes the resultant global to further GlobalOpt.
// We cannot optimize the malloc if we cannot determine malloc array size.
- Value *NElems = getMallocArraySize(CI, TD, true);
+ Value *NElems = getMallocArraySize(CI, TD, TLI, true);
if (!NElems)
return false;
// If this is a fixed size array, transform the Malloc to be an alloc of
// structs. malloc [100 x struct],1 -> malloc struct, 100
- if (ArrayType *AT = dyn_cast<ArrayType>(getMallocAllocatedType(CI))) {
+ if (ArrayType *AT = dyn_cast<ArrayType>(getMallocAllocatedType(CI, TLI))) {
Type *IntPtrTy = TD->getIntPtrType(CI->getContext());
unsigned TypeSize = TD->getStructLayout(AllocSTy)->getSizeInBytes();
Value *AllocSize = ConstantInt::get(IntPtrTy, TypeSize);
Instruction *Cast = new BitCastInst(Malloc, CI->getType(), "tmp", CI);
CI->replaceAllUsesWith(Cast);
CI->eraseFromParent();
- CI = dyn_cast<BitCastInst>(Malloc) ?
- extractMallocCallFromBitCast(Malloc) : cast<CallInst>(Malloc);
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(Malloc))
+ CI = cast<CallInst>(BCI->getOperand(0));
+ else
+ CI = cast<CallInst>(Malloc);
}
- GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD, true), TD);
+ GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD, TLI, true),
+ TD, TLI);
return true;
}
// Optimize away any trapping uses of the loaded value.
if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC, TD, TLI))
return true;
- } else if (CallInst *CI = extractMallocCall(StoredOnceVal)) {
- Type *MallocType = getMallocAllocatedType(CI);
+ } else if (CallInst *CI = extractMallocCall(StoredOnceVal, TLI)) {
+ Type *MallocType = getMallocAllocatedType(CI, TLI);
if (MallocType &&
TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, Ordering, GVI,
TD, TLI))
GlobalValue::InternalLinkage,
ConstantInt::getFalse(GV->getContext()),
GV->getName()+".b",
- GV->isThreadLocal());
+ GV->getThreadLocalMode());
GV->getParent()->getGlobalList().insert(GV, NewGV);
Constant *InitVal = GV->getInitializer();
/// possible. If we make a change, return true.
bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
Module::global_iterator &GVI) {
- if (!GV->hasLocalLinkage())
+ if (!GV->isDiscardableIfUnused())
return false;
// Do more involved optimizations if the global is internal.
return true;
}
+ if (!GV->hasLocalLinkage())
+ return false;
+
SmallPtrSet<const PHINode*, 16> PHIUsers;
GlobalStatus GS;
if (!GS.isLoaded) {
DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV);
- // Delete any stores we can find to the global. We may not be able to
- // make it completely dead though.
- bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(),
- TD, TLI);
+ bool Changed;
+ if (isLeakCheckerRoot(GV)) {
+ // Delete any constant stores to the global.
+ Changed = CleanupPointerRootUsers(GV, TLI);
+ } else {
+ // Delete any stores we can find to the global. We may not be able to
+ // make it completely dead though.
+ Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(), TD, TLI);
+ }
// If the global is dead now, delete it.
if (GV->use_empty()) {
if (GV->use_empty()) {
DEBUG(dbgs() << " *** Substituting initializer allowed us to "
- << "simplify all users and delete global!\n");
+ << "simplify all users and delete global!\n");
GV->eraseFromParent();
++NumDeleted;
} else {
/// function, changing them to FastCC.
static void ChangeCalleesToFastCall(Function *F) {
for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
+ if (isa<BlockAddress>(*UI))
+ continue;
CallSite User(cast<Instruction>(*UI));
User.setCallingConv(CallingConv::Fast);
}
static void RemoveNestAttribute(Function *F) {
F->setAttributes(StripNest(F->getAttributes()));
for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
+ if (isa<BlockAddress>(*UI))
+ continue;
CallSite User(cast<Instruction>(*UI));
User.setAttributes(StripNest(User.getAttributes()));
}
// Create the new global and insert it next to the existing list.
GlobalVariable *NGV = new GlobalVariable(CA->getType(), GCL->isConstant(),
GCL->getLinkage(), CA, "",
- GCL->isThreadLocal());
+ GCL->getThreadLocalMode());
GCL->getParent()->getGlobalList().insert(GCL, NGV);
NGV->takeName(GCL);
<< " stores.\n");
for (DenseMap<Constant*, Constant*>::const_iterator I =
Eval.getMutatedMemory().begin(), E = Eval.getMutatedMemory().end();
- I != E; ++I)
+ I != E; ++I)
CommitValueTo(I->second, I->first);
for (SmallPtrSet<GlobalVariable*, 8>::const_iterator I =
Eval.getInvariants().begin(), E = Eval.getInvariants().end();
projects / oota-llvm.git / blobdiff