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Make ValueIsOnlyUsedLocallyOrStoredToOneGlobal smart enough to see through

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bitcasts and phis.  This is a step to fixing PR1639.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41928 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-09-13 16:37:20 +00:00
parent 816861803f
commit c451f9c167
1 changed files with 16 additions and 5 deletions
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21
lib/Transforms/IPO/GlobalOpt.cpp
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@ -811,7 +811,8 @@ static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV,
/// like dereferencing the pointer, but not storing through the address, unless
/// it is to the specified global.
static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Instruction *V,
GlobalVariable *GV) {
GlobalVariable *GV,
SmallPtrSet<PHINode*, 8> &PHIs) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI)
if (isa<LoadInst>(*UI) || isa<CmpInst>(*UI)) {
// Fine, ignore.
@ -819,9 +820,16 @@ static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Instruction *V,
if (SI->getOperand(0) == V && SI->getOperand(1) != GV)
return false; // Storing the pointer itself... bad.
// Otherwise, storing through it, or storing into GV... fine.
} else if (isa<GetElementPtrInst>(*UI) || isa<SelectInst>(*UI)) {
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(cast<Instruction>(*UI),GV))
} else if (isa<GetElementPtrInst>(*UI) || isa<SelectInst>(*UI) ||
isa<BitCastInst>(*UI)) {
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(cast<Instruction>(*UI),
GV, PHIs))
return false;
} else if (PHINode *PN = dyn_cast<PHINode>(*UI)) {
// PHIs are ok if all uses are ok. Don't infinitely recurse through PHI
// cycles.
if (PHIs.insert(PN))
return ValueIsOnlyUsedLocallyOrStoredToOneGlobal(PN, GV, PHIs);
} else {
return false;
}
@ -1125,8 +1133,11 @@ static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
// malloc to be stored into the specified global, loaded setcc'd, and
// GEP'd. These are all things we could transform to using the global
// for.
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(MI, GV))
return false;
{
SmallPtrSet<PHINode*, 8> PHIs;
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(MI, GV, PHIs))
return false;
}
// If we have a global that is only initialized with a fixed size malloc,