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Add support for getelementptr, load, and correctly reject volatile stores.

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llvm-svn: 23441
This commit is contained in:
Chris Lattner 2005-09-26 05:15:37 +00:00
parent 6bb22ee24c
commit 2addd0dcab
1 changed files with 29 additions and 0 deletions
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29
lib/Transforms/IPO/GlobalOpt.cpp
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@ -1263,6 +1263,23 @@ static void CommitValueTo(Constant *Val, Constant *Addr) {
GV->setInitializer(Val);
}
static Constant *ComputeLoadResult(Constant *P,
const std::map<Constant*, Constant*> &Memory) {
// If this memory location has been recently stored, use the stored value: it
// is the most up-to-date.
std::map<Constant*, Constant*>::const_iterator I = Memory.find(P);
if (I != Memory.end()) return I->second;
// Access it.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) {
if (GV->hasInitializer())
return GV->getInitializer();
return 0;
} else {
return 0; // don't know how to evaluate.
}
}
/// EvaluateStaticConstructor - Evaluate static constructors in the function, if
/// we can. Return true if we can, false otherwise.
static bool EvaluateStaticConstructor(Function *F) {
@ -1288,6 +1305,7 @@ static bool EvaluateStaticConstructor(Function *F) {
Constant *InstResult = 0;
if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) {
if (SI->isVolatile()) return false; // no volatile accesses.
Constant *Ptr = getVal(Values, SI->getOperand(1));
if (!isSimpleEnoughPointerToCommit(Ptr))
// If this is too complex for us to commit, reject it.
@ -1309,6 +1327,17 @@ static bool EvaluateStaticConstructor(Function *F) {
InstResult = ConstantExpr::getSelect(getVal(Values, SI->getOperand(0)),
getVal(Values, SI->getOperand(1)),
getVal(Values, SI->getOperand(2)));
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
Constant *P = getVal(Values, GEP->getOperand(0));
std::vector<Constant*> GEPOps;
for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
GEPOps.push_back(getVal(Values, GEP->getOperand(i)));
InstResult = ConstantExpr::getGetElementPtr(P, GEPOps);
} else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
if (LI->isVolatile()) return false; // no volatile accesses.
InstResult = ComputeLoadResult(getVal(Values, LI->getOperand(0)),
MutatedMemory);
if (InstResult == 0) return false; // Could not evaluate load.
} else if (TerminatorInst *TI = dyn_cast<TerminatorInst>(CurInst)) {
BasicBlock *NewBB = 0;
if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {