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llvm-svn: 17161
This commit is contained in:
Chris Lattner 2004-10-22 06:43:28 +00:00
parent 8079adb986
commit f0e2ce2279
1 changed files with 47 additions and 4 deletions
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51
lib/Transforms/IPO/GlobalOpt.cpp
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@ -458,6 +458,9 @@ static bool AllUsesOfValueWillTrapIfNull(Value *V) {
if (!AllUsesOfValueWillTrapIfNull(CI)) return false;
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI)) {
if (!AllUsesOfValueWillTrapIfNull(GEPI)) return false;
} else if (isa<SetCondInst>(*UI) &&
isa<ConstantPointerNull>(UI->getOperand(1))) {
// Ignore setcc X, null
} else {
//std::cerr << "NONTRAPPING USE: " << **UI;
return false;
@ -466,7 +469,8 @@ static bool AllUsesOfValueWillTrapIfNull(Value *V) {
}
/// AllUsesOfLoadedValueWillTrapIfNull - Return true if all uses of any loads
/// from GV will trap if the loaded value is null.
/// from GV will trap if the loaded value is null. Note that this also permits
/// comparisons of the loaded value against null, as a special case.
static bool AllUsesOfLoadedValueWillTrapIfNull(GlobalVariable *GV) {
for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI!=E; ++UI)
if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
@ -653,24 +657,63 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV,
// Anything that used the malloc now uses the global directly.
MI->replaceAllUsesWith(NewGV);
MI->eraseFromParent();
Constant *RepValue = NewGV;
if (NewGV->getType() != GV->getType()->getElementType())
RepValue = ConstantExpr::getCast(RepValue, GV->getType()->getElementType());
// If there is a comparison against null, we will insert a global bool to
// keep track of whether the global was initialized yet or not.
GlobalVariable *InitBool = 0;
// Loop over all uses of GV, processing them in turn.
while (!GV->use_empty())
if (LoadInst *LI = dyn_cast<LoadInst>(GV->use_back())) {
LI->replaceAllUsesWith(RepValue);
while (!LI->use_empty()) {
// FIXME: the iterator should expose a getUse() method.
Use &LoadUse = *(const iplist<Use>::iterator&)LI->use_begin();
if (!isa<SetCondInst>(LoadUse.getUser()))
LoadUse = RepValue;
else {
if (InitBool == 0) {
InitBool = new GlobalVariable(Type::BoolTy, false,
GlobalValue::InternalLinkage,
ConstantBool::False,
GV->getName()+".init");
GV->getParent()->getGlobalList().insert(GV, InitBool);
// The global is initialized when the malloc is run.
new StoreInst(ConstantBool::True, InitBool, MI);
}
// Replace the setcc X, 0 with a use of the bool value.
SetCondInst *SCI = cast<SetCondInst>(LoadUse.getUser());
Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", SCI);
switch (SCI->getOpcode()) {
default: assert(0 && "Unknown opcode!");
case Instruction::SetLT:
LV = ConstantBool::False; // X < null -> always false
break;
case Instruction::SetEQ:
case Instruction::SetLE:
LV = BinaryOperator::createNot(LV, "notinit", SCI);
break;
case Instruction::SetNE:
case Instruction::SetGE:
case Instruction::SetGT:
break; // no change.
}
SCI->replaceAllUsesWith(LV);
SCI->eraseFromParent();
}
}
LI->eraseFromParent();
} else {
StoreInst *SI = cast<StoreInst>(GV->use_back());
SI->eraseFromParent();
}
// Now the GV is dead, nuke it.
// Now the GV is dead, nuke it and the malloc.
GV->eraseFromParent();
MI->eraseFromParent();
// To further other optimizations, loop over all users of NewGV and try to
// constant prop them. This will promote GEP instructions with constant