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Avoid infinite looping in AllGlobalLoadUsesSimpleEnoughForHeapSRA(). This can happen when PHI uses are recursively dependent on each other.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72710 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2009-06-02 00:56:07 +00:00
parent ca46fdd284
commit 5d16396a33
2 changed files with 133 additions and 6 deletions
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22
lib/Transforms/IPO/GlobalOpt.cpp
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@ -1020,7 +1020,8 @@ static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
/// of a load) are simple enough to perform heap SRA on. This permits GEP's
/// that index through the array and struct field, icmps of null, and PHIs.
static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
SmallPtrSet<PHINode*, 32> &LoadUsingPHIs) {
SmallPtrSet<PHINode*, 32> &LoadUsingPHIs,
SmallPtrSet<PHINode*, 32> &LoadUsingPHIsPerLoad) {
// We permit two users of the load: setcc comparing against the null
// pointer, and a getelementptr of a specific form.
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
@ -1044,12 +1045,17 @@ static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
}
if (PHINode *PN = dyn_cast<PHINode>(User)) {
// If we have already recursively analyzed this PHI, then it is safe.
if (LoadUsingPHIs.insert(PN))
if (!LoadUsingPHIsPerLoad.insert(PN))
// This means some phi nodes are dependent on each other.
// Avoid infinite looping!
return false;
if (!LoadUsingPHIs.insert(PN))
// If we have already analyzed this PHI, then it is safe.
continue;
// Make sure all uses of the PHI are simple enough to transform.
if (!LoadUsesSimpleEnoughForHeapSRA(PN, LoadUsingPHIs))
if (!LoadUsesSimpleEnoughForHeapSRA(PN,
LoadUsingPHIs, LoadUsingPHIsPerLoad))
return false;
continue;
@ -1068,11 +1074,15 @@ static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
MallocInst *MI) {
SmallPtrSet<PHINode*, 32> LoadUsingPHIs;
SmallPtrSet<PHINode*, 32> LoadUsingPHIsPerLoad;
for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;
++UI)
if (LoadInst *LI = dyn_cast<LoadInst>(*UI))
if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs))
if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs,
LoadUsingPHIsPerLoad))
return false;
LoadUsingPHIsPerLoad.clear();
}
// If we reach here, we know that all uses of the loads and transitive uses
// (through PHI nodes) are simple enough to transform. However, we don't know