const SmallPtrSet<const PHINode*, 16> &PHIUsers,
const GlobalStatus &GS);
bool OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn);
+
+ TargetData *TD;
+ TargetLibraryInfo *TLI;
};
}
/// 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
/// returns true if it made a change.
-static bool CleanupConstantGlobalUsers(Value *V, Constant *Init) {
+static bool CleanupConstantGlobalUsers(Value *V, Constant *Init,
+ TargetData *TD, TargetLibraryInfo *TLI) {
bool Changed = false;
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;) {
User *U = *UI++;
Constant *SubInit = 0;
if (Init)
SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
- Changed |= CleanupConstantGlobalUsers(CE, SubInit);
+ Changed |= CleanupConstantGlobalUsers(CE, SubInit, TD, TLI);
} else if (CE->getOpcode() == Instruction::BitCast &&
CE->getType()->isPointerTy()) {
// Pointer cast, delete any stores and memsets to the global.
- Changed |= CleanupConstantGlobalUsers(CE, 0);
+ Changed |= CleanupConstantGlobalUsers(CE, 0, TD, TLI);
}
if (CE->use_empty()) {
// and will invalidate our notion of what Init is.
Constant *SubInit = 0;
if (!isa<ConstantExpr>(GEP->getOperand(0))) {
- // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding.
ConstantExpr *CE =
- dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP));
+ dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP, TD, TLI));
if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr)
SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
}
- Changed |= CleanupConstantGlobalUsers(GEP, SubInit);
+ Changed |= CleanupConstantGlobalUsers(GEP, SubInit, TD, TLI);
if (GEP->use_empty()) {
GEP->eraseFromParent();
if (SafeToDestroyConstant(C)) {
C->destroyConstant();
// This could have invalidated UI, start over from scratch.
- CleanupConstantGlobalUsers(V, Init);
+ CleanupConstantGlobalUsers(V, Init, TD, TLI);
return true;
}
}
/// value stored into it. If there are uses of the loaded value that would trap
/// if the loaded value is dynamically null, then we know that they cannot be
/// reachable with a null optimize away the load.
-static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV) {
+static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV,
+ TargetData *TD,
+ TargetLibraryInfo *TLI) {
bool Changed = false;
// Keep track of whether we are able to remove all the uses of the global
// nor is the global.
if (AllNonStoreUsesGone) {
DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
- CleanupConstantGlobalUsers(GV, 0);
+ CleanupConstantGlobalUsers(GV, 0, TD, TLI);
if (GV->use_empty()) {
GV->eraseFromParent();
++NumDeleted;
/// ConstantPropUsersOf - Walk the use list of V, constant folding all of the
/// instructions that are foldable.
-static void ConstantPropUsersOf(Value *V) {
+static void ConstantPropUsersOf(Value *V,
+ TargetData *TD, TargetLibraryInfo *TLI) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; )
if (Instruction *I = dyn_cast<Instruction>(*UI++))
- // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding.
- if (Constant *NewC = ConstantFoldInstruction(I)) {
+ if (Constant *NewC = ConstantFoldInstruction(I, TD, TLI)) {
I->replaceAllUsesWith(NewC);
// Advance UI to the next non-I use to avoid invalidating it!
CallInst *CI,
Type *AllocTy,
ConstantInt *NElements,
- TargetData *TD) {
+ TargetData *TD,
+ TargetLibraryInfo *TLI) {
DEBUG(errs() << "PROMOTING GLOBAL: " << *GV << " CALL = " << *CI << '\n');
Type *GlobalType;
// To further other optimizations, loop over all users of NewGV and try to
// constant prop them. This will promote GEP instructions with constant
// indices into GEP constant-exprs, which will allow global-opt to hack on it.
- ConstantPropUsersOf(NewGV);
+ ConstantPropUsersOf(NewGV, TD, TLI);
if (RepValue != NewGV)
- ConstantPropUsersOf(RepValue);
+ ConstantPropUsersOf(RepValue, TD, TLI);
return NewGV;
}
Type *AllocTy,
AtomicOrdering Ordering,
Module::global_iterator &GVI,
- TargetData *TD) {
+ TargetData *TD,
+ TargetLibraryInfo *TLI) {
if (!TD)
return false;
// (2048 bytes currently), as we don't want to introduce a 16M global or
// something.
if (NElements->getZExtValue() * TD->getTypeAllocSize(AllocTy) < 2048) {
- GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, TD);
+ GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, TD, TLI);
return true;
}
static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
AtomicOrdering Ordering,
Module::global_iterator &GVI,
- TargetData *TD) {
+ TargetData *TD, TargetLibraryInfo *TLI) {
// Ignore no-op GEPs and bitcasts.
StoredOnceVal = StoredOnceVal->stripPointerCasts();
SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
// Optimize away any trapping uses of the loaded value.
- if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC))
+ if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC, TD, TLI))
return true;
} else if (CallInst *CI = extractMallocCall(StoredOnceVal)) {
Type *MallocType = getMallocAllocatedType(CI);
- if (MallocType && TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType,
- Ordering, GVI, TD))
+ if (MallocType &&
+ TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, Ordering, GVI,
+ TD, TLI))
return true;
}
}
}
-/// ProcessInternalGlobal - Analyze the specified global variable and optimize
-/// it if possible. If we make a change, return true.
+/// ProcessGlobal - Analyze the specified global variable and optimize it if
+/// possible. If we make a change, return true.
bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
Module::global_iterator &GVI) {
if (!GV->hasLocalLinkage())
/// it if possible. If we make a change, return true.
bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
Module::global_iterator &GVI,
- const SmallPtrSet<const PHINode*, 16> &PHIUsers,
+ const SmallPtrSet<const PHINode*, 16> &PHIUsers,
const GlobalStatus &GS) {
// If this is a first class global and has only one accessing function
// and this function is main (which we know is not recursive we can make
// 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());
+ bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(),
+ TD, TLI);
// If the global is dead now, delete it.
if (GV->use_empty()) {
GV->setConstant(true);
// Clean up any obviously simplifiable users now.
- CleanupConstantGlobalUsers(GV, GV->getInitializer());
+ CleanupConstantGlobalUsers(GV, GV->getInitializer(), TD, TLI);
// If the global is dead now, just nuke it.
if (GV->use_empty()) {
GV->setInitializer(SOVConstant);
// Clean up any obviously simplifiable users now.
- CleanupConstantGlobalUsers(GV, GV->getInitializer());
+ CleanupConstantGlobalUsers(GV, GV->getInitializer(), TD, TLI);
if (GV->use_empty()) {
DEBUG(dbgs() << " *** Substituting initializer allowed us to "
// Try to optimize globals based on the knowledge that only one value
// (besides its initializer) is ever stored to the global.
if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GS.Ordering, GVI,
- getAnalysisIfAvailable<TargetData>()))
+ TD, TLI))
return true;
// Otherwise, if the global was not a boolean, we can shrink it to be a
// Simplify the initializer.
if (GV->hasInitializer())
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GV->getInitializer())) {
- TargetData *TD = getAnalysisIfAvailable<TargetData>();
- TargetLibraryInfo *TLI = &getAnalysis<TargetLibraryInfo>();
Constant *New = ConstantFoldConstantExpression(CE, TD, TLI);
if (New && New != CE)
GV->setInitializer(New);
}
-static Constant *getVal(DenseMap<Value*, Constant*> &ComputedValues, Value *V) {
- if (Constant *CV = dyn_cast<Constant>(V)) return CV;
- Constant *R = ComputedValues[V];
- assert(R && "Reference to an uncomputed value!");
- return R;
-}
-
static inline bool
isSimpleEnoughValueToCommit(Constant *C,
SmallPtrSet<Constant*, 8> &SimpleConstants,
GV->setInitializer(EvaluateStoreInto(GV->getInitializer(), Val, CE, 2));
}
+namespace {
+
+/// Evaluator - This class evaluates LLVM IR, producing the Constant
+/// representing each SSA instruction. Changes to global variables are stored
+/// in a mapping that can be iterated over after the evaluation is complete.
+/// Once an evaluation call fails, the evaluation object should not be reused.
+class Evaluator {
+public:
+ Evaluator(const TargetData *TD, const TargetLibraryInfo *TLI)
+ : TD(TD), TLI(TLI) {
+ ValueStack.push_back(new DenseMap<Value*, Constant*>);
+ }
+
+ ~Evaluator() {
+ DeleteContainerPointers(ValueStack);
+ while (!AllocaTmps.empty()) {
+ GlobalVariable *Tmp = AllocaTmps.back();
+ AllocaTmps.pop_back();
+
+ // If there are still users of the alloca, the program is doing something
+ // silly, e.g. storing the address of the alloca somewhere and using it
+ // later. Since this is undefined, we'll just make it be null.
+ if (!Tmp->use_empty())
+ Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType()));
+ delete Tmp;
+ }
+ }
+
+ /// EvaluateFunction - Evaluate a call to function F, returning true if
+ /// successful, false if we can't evaluate it. ActualArgs contains the formal
+ /// arguments for the function.
+ bool EvaluateFunction(Function *F, Constant *&RetVal,
+ const SmallVectorImpl<Constant*> &ActualArgs);
+
+ /// EvaluateBlock - Evaluate all instructions in block BB, returning true if
+ /// successful, false if we can't evaluate it. NewBB returns the next BB that
+ /// control flows into, or null upon return.
+ bool EvaluateBlock(BasicBlock::iterator CurInst, BasicBlock *&NextBB);
+
+ Constant *getVal(Value *V) {
+ if (Constant *CV = dyn_cast<Constant>(V)) return CV;
+ Constant *R = ValueStack.back()->lookup(V);
+ assert(R && "Reference to an uncomputed value!");
+ return R;
+ }
+
+ void setVal(Value *V, Constant *C) {
+ ValueStack.back()->operator[](V) = C;
+ }
+
+ const DenseMap<Constant*, Constant*> &getMutatedMemory() const {
+ return MutatedMemory;
+ }
+
+ const SmallPtrSet<GlobalVariable*, 8> &getInvariants() const {
+ return Invariants;
+ }
+
+private:
+ Constant *ComputeLoadResult(Constant *P);
+
+ /// ValueStack - As we compute SSA register values, we store their contents
+ /// here. The back of the vector contains the current function and the stack
+ /// contains the values in the calling frames.
+ SmallVector<DenseMap<Value*, Constant*>*, 4> ValueStack;
+
+ /// CallStack - This is used to detect recursion. In pathological situations
+ /// we could hit exponential behavior, but at least there is nothing
+ /// unbounded.
+ SmallVector<Function*, 4> CallStack;
+
+ /// MutatedMemory - For each store we execute, we update this map. Loads
+ /// check this to get the most up-to-date value. If evaluation is successful,
+ /// this state is committed to the process.
+ DenseMap<Constant*, Constant*> MutatedMemory;
+
+ /// AllocaTmps - To 'execute' an alloca, we create a temporary global variable
+ /// to represent its body. This vector is needed so we can delete the
+ /// temporary globals when we are done.
+ SmallVector<GlobalVariable*, 32> AllocaTmps;
+
+ /// Invariants - These global variables have been marked invariant by the
+ /// static constructor.
+ SmallPtrSet<GlobalVariable*, 8> Invariants;
+
+ /// SimpleConstants - These are constants we have checked and know to be
+ /// simple enough to live in a static initializer of a global.
+ SmallPtrSet<Constant*, 8> SimpleConstants;
+
+ const TargetData *TD;
+ const TargetLibraryInfo *TLI;
+};
+
+} // anonymous namespace
+
/// ComputeLoadResult - Return the value that would be computed by a load from
/// P after the stores reflected by 'memory' have been performed. If we can't
/// decide, return null.
-static Constant *ComputeLoadResult(Constant *P,
- const DenseMap<Constant*, Constant*> &Memory) {
+Constant *Evaluator::ComputeLoadResult(Constant *P) {
// If this memory location has been recently stored, use the stored value: it
// is the most up-to-date.
- DenseMap<Constant*, Constant*>::const_iterator I = Memory.find(P);
- if (I != Memory.end()) return I->second;
+ DenseMap<Constant*, Constant*>::const_iterator I = MutatedMemory.find(P);
+ if (I != MutatedMemory.end()) return I->second;
// Access it.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) {
return 0; // don't know how to evaluate.
}
-static bool EvaluateFunction(Function *F, Constant *&RetVal,
- const SmallVectorImpl<Constant*> &ActualArgs,
- std::vector<Function*> &CallStack,
- DenseMap<Constant*, Constant*> &MutatedMemory,
- std::vector<GlobalVariable*> &AllocaTmps,
- SmallPtrSet<Constant*, 8> &SimpleConstants,
- const TargetData *TD,
- const TargetLibraryInfo *TLI);
-
/// EvaluateBlock - Evaluate all instructions in block BB, returning true if
/// successful, false if we can't evaluate it. NewBB returns the next BB that
/// control flows into, or null upon return.
-static bool EvaluateBlock(BasicBlock *BB, BasicBlock *&NextBB,
- std::vector<Function*> &CallStack,
- DenseMap<Value*, Constant*> &Values,
- DenseMap<Constant*, Constant*> &MutatedMemory,
- std::vector<GlobalVariable*> &AllocaTmps,
- SmallPtrSet<Constant*, 8> &SimpleConstants,
- const TargetData *TD,
- const TargetLibraryInfo *TLI) {
- // CurInst - The current instruction we're evaluating.
- BasicBlock::iterator CurInst = BB->getFirstNonPHI();
-
+bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
+ BasicBlock *&NextBB) {
// This is the main evaluation loop.
while (1) {
Constant *InstResult = 0;
if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) {
if (!SI->isSimple()) return false; // no volatile/atomic accesses.
- Constant *Ptr = getVal(Values, SI->getOperand(1));
+ Constant *Ptr = getVal(SI->getOperand(1));
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
if (!isSimpleEnoughPointerToCommit(Ptr))
// If this is too complex for us to commit, reject it.
return false;
- Constant *Val = getVal(Values, SI->getOperand(0));
+ Constant *Val = getVal(SI->getOperand(0));
// If this might be too difficult for the backend to handle (e.g. the addr
// of one global variable divided by another) then we can't commit it.
Constant * const IdxList[] = {IdxZero, IdxZero};
Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList);
-
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
+
// If we can't improve the situation by introspecting NewTy,
// we have to give up.
} else {
MutatedMemory[Ptr] = Val;
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) {
InstResult = ConstantExpr::get(BO->getOpcode(),
- getVal(Values, BO->getOperand(0)),
- getVal(Values, BO->getOperand(1)));
+ getVal(BO->getOperand(0)),
+ getVal(BO->getOperand(1)));
} else if (CmpInst *CI = dyn_cast<CmpInst>(CurInst)) {
InstResult = ConstantExpr::getCompare(CI->getPredicate(),
- getVal(Values, CI->getOperand(0)),
- getVal(Values, CI->getOperand(1)));
+ getVal(CI->getOperand(0)),
+ getVal(CI->getOperand(1)));
} else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) {
InstResult = ConstantExpr::getCast(CI->getOpcode(),
- getVal(Values, CI->getOperand(0)),
+ getVal(CI->getOperand(0)),
CI->getType());
} else if (SelectInst *SI = dyn_cast<SelectInst>(CurInst)) {
- InstResult = ConstantExpr::getSelect(getVal(Values, SI->getOperand(0)),
- getVal(Values, SI->getOperand(1)),
- getVal(Values, SI->getOperand(2)));
+ InstResult = ConstantExpr::getSelect(getVal(SI->getOperand(0)),
+ getVal(SI->getOperand(1)),
+ getVal(SI->getOperand(2)));
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
- Constant *P = getVal(Values, GEP->getOperand(0));
+ Constant *P = getVal(GEP->getOperand(0));
SmallVector<Constant*, 8> GEPOps;
for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end();
i != e; ++i)
- GEPOps.push_back(getVal(Values, *i));
+ GEPOps.push_back(getVal(*i));
InstResult =
ConstantExpr::getGetElementPtr(P, GEPOps,
cast<GEPOperator>(GEP)->isInBounds());
} else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
if (!LI->isSimple()) return false; // no volatile/atomic accesses.
- InstResult = ComputeLoadResult(getVal(Values, LI->getOperand(0)),
- MutatedMemory);
+ Constant *Ptr = getVal(LI->getOperand(0));
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
+ InstResult = ComputeLoadResult(Ptr);
if (InstResult == 0) return false; // Could not evaluate load.
} else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) {
if (AI->isArrayAllocation()) return false; // Cannot handle array allocs.
UndefValue::get(Ty),
AI->getName()));
InstResult = AllocaTmps.back();
- } else if (CallInst *CI = dyn_cast<CallInst>(CurInst)) {
+ } else if (isa<CallInst>(CurInst) || isa<InvokeInst>(CurInst)) {
+ CallSite CS(CurInst);
// Debug info can safely be ignored here.
- if (isa<DbgInfoIntrinsic>(CI)) {
+ if (isa<DbgInfoIntrinsic>(CS.getInstruction())) {
++CurInst;
continue;
}
// Cannot handle inline asm.
- if (isa<InlineAsm>(CI->getCalledValue())) return false;
-
- if (MemSetInst *MSI = dyn_cast<MemSetInst>(CI)) {
- if (MSI->isVolatile()) return false;
- Constant *Ptr = getVal(Values, MSI->getDest());
- Constant *Val = getVal(Values, MSI->getValue());
- Constant *DestVal = ComputeLoadResult(getVal(Values, Ptr),
- MutatedMemory);
- if (Val->isNullValue() && DestVal && DestVal->isNullValue()) {
- // This memset is a no-op.
+ if (isa<InlineAsm>(CS.getCalledValue())) return false;
+
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(II)) {
+ if (MSI->isVolatile()) return false;
+ Constant *Ptr = getVal(MSI->getDest());
+ Constant *Val = getVal(MSI->getValue());
+ Constant *DestVal = ComputeLoadResult(getVal(Ptr));
+ if (Val->isNullValue() && DestVal && DestVal->isNullValue()) {
+ // This memset is a no-op.
+ ++CurInst;
+ continue;
+ }
+ }
+
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
+ II->getIntrinsicID() == Intrinsic::lifetime_end) {
+ ++CurInst;
+ continue;
+ }
+
+ if (II->getIntrinsicID() == Intrinsic::invariant_start) {
+ // We don't insert an entry into Values, as it doesn't have a
+ // meaningful return value.
+ if (!II->use_empty())
+ return false;
+ ConstantInt *Size = cast<ConstantInt>(II->getArgOperand(0));
+ Value *PtrArg = getVal(II->getArgOperand(1));
+ Value *Ptr = PtrArg->stripPointerCasts();
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
+ Type *ElemTy = cast<PointerType>(GV->getType())->getElementType();
+ if (!Size->isAllOnesValue() &&
+ Size->getValue().getLimitedValue() >=
+ TD->getTypeStoreSize(ElemTy))
+ Invariants.insert(GV);
+ }
+ // Continue even if we do nothing.
++CurInst;
continue;
}
}
// Resolve function pointers.
- Function *Callee = dyn_cast<Function>(getVal(Values,
- CI->getCalledValue()));
- if (!Callee) return false; // Cannot resolve.
+ Function *Callee = dyn_cast<Function>(getVal(CS.getCalledValue()));
+ if (!Callee || Callee->mayBeOverridden())
+ return false; // Cannot resolve.
SmallVector<Constant*, 8> Formals;
- CallSite CS(CI);
- for (User::op_iterator i = CS.arg_begin(), e = CS.arg_end();
- i != e; ++i)
- Formals.push_back(getVal(Values, *i));
+ for (User::op_iterator i = CS.arg_begin(), e = CS.arg_end(); i != e; ++i)
+ Formals.push_back(getVal(*i));
if (Callee->isDeclaration()) {
// If this is a function we can constant fold, do it.
Constant *RetVal;
// Execute the call, if successful, use the return value.
- if (!EvaluateFunction(Callee, RetVal, Formals, CallStack,
- MutatedMemory, AllocaTmps, SimpleConstants, TD,
- TLI))
+ ValueStack.push_back(new DenseMap<Value*, Constant*>);
+ if (!EvaluateFunction(Callee, RetVal, Formals))
return false;
+ ValueStack.pop_back();
InstResult = RetVal;
+
+ if (InvokeInst *II = dyn_cast<InvokeInst>(CurInst)) {
+ NextBB = II->getNormalDest();
+ return true;
+ }
}
} else if (isa<TerminatorInst>(CurInst)) {
if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
NextBB = BI->getSuccessor(0);
} else {
ConstantInt *Cond =
- dyn_cast<ConstantInt>(getVal(Values, BI->getCondition()));
+ dyn_cast<ConstantInt>(getVal(BI->getCondition()));
if (!Cond) return false; // Cannot determine.
NextBB = BI->getSuccessor(!Cond->getZExtValue());
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
ConstantInt *Val =
- dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
+ dyn_cast<ConstantInt>(getVal(SI->getCondition()));
if (!Val) return false; // Cannot determine.
unsigned ValTISucc = SI->resolveSuccessorIndex(SI->findCaseValue(Val));
NextBB = SI->getSuccessor(ValTISucc);
} else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(CurInst)) {
- Value *Val = getVal(Values, IBI->getAddress())->stripPointerCasts();
+ Value *Val = getVal(IBI->getAddress())->stripPointerCasts();
if (BlockAddress *BA = dyn_cast<BlockAddress>(Val))
NextBB = BA->getBasicBlock();
else
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(InstResult))
InstResult = ConstantFoldConstantExpression(CE, TD, TLI);
- Values[CurInst] = InstResult;
+ setVal(CurInst, InstResult);
}
// Advance program counter.
/// EvaluateFunction - Evaluate a call to function F, returning true if
/// successful, false if we can't evaluate it. ActualArgs contains the formal
/// arguments for the function.
-static bool EvaluateFunction(Function *F, Constant *&RetVal,
- const SmallVectorImpl<Constant*> &ActualArgs,
- std::vector<Function*> &CallStack,
- DenseMap<Constant*, Constant*> &MutatedMemory,
- std::vector<GlobalVariable*> &AllocaTmps,
- SmallPtrSet<Constant*, 8> &SimpleConstants,
- const TargetData *TD,
- const TargetLibraryInfo *TLI) {
+bool Evaluator::EvaluateFunction(Function *F, Constant *&RetVal,
+ const SmallVectorImpl<Constant*> &ActualArgs) {
// Check to see if this function is already executing (recursion). If so,
// bail out. TODO: we might want to accept limited recursion.
if (std::find(CallStack.begin(), CallStack.end(), F) != CallStack.end())
CallStack.push_back(F);
- /// Values - As we compute SSA register values, we store their contents here.
- DenseMap<Value*, Constant*> Values;
-
// Initialize arguments to the incoming values specified.
unsigned ArgNo = 0;
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E;
++AI, ++ArgNo)
- Values[AI] = ActualArgs[ArgNo];
+ setVal(AI, ActualArgs[ArgNo]);
// ExecutedBlocks - We only handle non-looping, non-recursive code. As such,
// we can only evaluate any one basic block at most once. This set keeps
// CurBB - The current basic block we're evaluating.
BasicBlock *CurBB = F->begin();
+ BasicBlock::iterator CurInst = CurBB->begin();
+
while (1) {
- BasicBlock *NextBB;
- if (!EvaluateBlock(CurBB, NextBB, CallStack, Values, MutatedMemory,
- AllocaTmps, SimpleConstants, TD, TLI))
+ BasicBlock *NextBB = 0; // Initialized to avoid compiler warnings.
+ if (!EvaluateBlock(CurInst, NextBB))
return false;
if (NextBB == 0) {
// the return. Fill it the return value and pop the call stack.
ReturnInst *RI = cast<ReturnInst>(CurBB->getTerminator());
if (RI->getNumOperands())
- RetVal = getVal(Values, RI->getOperand(0));
+ RetVal = getVal(RI->getOperand(0));
CallStack.pop_back();
return true;
}
// are any PHI nodes. If so, evaluate them with information about where
// we came from.
PHINode *PN = 0;
- for (BasicBlock::iterator Inst = NextBB->begin();
- (PN = dyn_cast<PHINode>(Inst)); ++Inst)
- Values[PN] = getVal(Values, PN->getIncomingValueForBlock(CurBB));
+ for (CurInst = NextBB->begin();
+ (PN = dyn_cast<PHINode>(CurInst)); ++CurInst)
+ setVal(PN, getVal(PN->getIncomingValueForBlock(CurBB)));
// Advance to the next block.
CurBB = NextBB;
/// we can. Return true if we can, false otherwise.
static bool EvaluateStaticConstructor(Function *F, const TargetData *TD,
const TargetLibraryInfo *TLI) {
- /// MutatedMemory - For each store we execute, we update this map. Loads
- /// check this to get the most up-to-date value. If evaluation is successful,
- /// this state is committed to the process.
- DenseMap<Constant*, Constant*> MutatedMemory;
-
- /// AllocaTmps - To 'execute' an alloca, we create a temporary global variable
- /// to represent its body. This vector is needed so we can delete the
- /// temporary globals when we are done.
- std::vector<GlobalVariable*> AllocaTmps;
-
- /// CallStack - This is used to detect recursion. In pathological situations
- /// we could hit exponential behavior, but at least there is nothing
- /// unbounded.
- std::vector<Function*> CallStack;
-
- /// SimpleConstants - These are constants we have checked and know to be
- /// simple enough to live in a static initializer of a global.
- SmallPtrSet<Constant*, 8> SimpleConstants;
-
// Call the function.
+ Evaluator Eval(TD, TLI);
Constant *RetValDummy;
- bool EvalSuccess = EvaluateFunction(F, RetValDummy,
- SmallVector<Constant*, 0>(), CallStack,
- MutatedMemory, AllocaTmps,
- SimpleConstants, TD, TLI);
+ bool EvalSuccess = Eval.EvaluateFunction(F, RetValDummy,
+ SmallVector<Constant*, 0>());
if (EvalSuccess) {
// We succeeded at evaluation: commit the result.
DEBUG(dbgs() << "FULLY EVALUATED GLOBAL CTOR FUNCTION '"
- << F->getName() << "' to " << MutatedMemory.size()
+ << F->getName() << "' to " << Eval.getMutatedMemory().size()
<< " stores.\n");
- for (DenseMap<Constant*, Constant*>::iterator I = MutatedMemory.begin(),
- E = MutatedMemory.end(); I != E; ++I)
+ for (DenseMap<Constant*, Constant*>::const_iterator I =
+ Eval.getMutatedMemory().begin(), E = Eval.getMutatedMemory().end();
+ I != E; ++I)
CommitValueTo(I->second, I->first);
- }
-
- // At this point, we are done interpreting. If we created any 'alloca'
- // temporaries, release them now.
- while (!AllocaTmps.empty()) {
- GlobalVariable *Tmp = AllocaTmps.back();
- AllocaTmps.pop_back();
-
- // If there are still users of the alloca, the program is doing something
- // silly, e.g. storing the address of the alloca somewhere and using it
- // later. Since this is undefined, we'll just make it be null.
- if (!Tmp->use_empty())
- Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType()));
- delete Tmp;
+ for (SmallPtrSet<GlobalVariable*, 8>::const_iterator I =
+ Eval.getInvariants().begin(), E = Eval.getInvariants().end();
+ I != E; ++I)
+ (*I)->setConstant(true);
}
return EvalSuccess;
bool MadeChange = false;
if (Ctors.empty()) return false;
- const TargetData *TD = getAnalysisIfAvailable<TargetData>();
- const TargetLibraryInfo *TLI = &getAnalysis<TargetLibraryInfo>();
-
// Loop over global ctors, optimizing them when we can.
for (unsigned i = 0; i != Ctors.size(); ++i) {
Function *F = Ctors[i];
return Changed;
}
-static Function *FindCXAAtExit(Module &M) {
- Function *Fn = M.getFunction("__cxa_atexit");
+static Function *FindCXAAtExit(Module &M, TargetLibraryInfo *TLI) {
+ if (!TLI->has(LibFunc::cxa_atexit))
+ return 0;
+
+ Function *Fn = M.getFunction(TLI->getName(LibFunc::cxa_atexit));
if (!Fn)
return 0;
-
+
FunctionType *FTy = Fn->getFunctionType();
// Checking that the function has the right return type, the right number of
/// destructor and can therefore be eliminated.
/// Note that we assume that other optimization passes have already simplified
/// the code so we only look for a function with a single basic block, where
-/// the only allowed instructions side-effect free, 'ret' or 'call' to empty
-/// C++ dtor.
+/// the only allowed instructions are 'ret', 'call' to an empty C++ dtor and
+/// other side-effect free instructions.
static bool cxxDtorIsEmpty(const Function &Fn,
SmallPtrSet<const Function *, 8> &CalledFunctions) {
// FIXME: We could eliminate C++ destructors if they're readonly/readnone and
bool GlobalOpt::runOnModule(Module &M) {
bool Changed = false;
+ TD = getAnalysisIfAvailable<TargetData>();
+ TLI = &getAnalysis<TargetLibraryInfo>();
+
// Try to find the llvm.globalctors list.
GlobalVariable *GlobalCtors = FindGlobalCtors(M);
- Function *CXAAtExitFn = FindCXAAtExit(M);
+ Function *CXAAtExitFn = FindCXAAtExit(M, TLI);
bool LocalChange = true;
while (LocalChange) {
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