Make ValueIsOnlyUsedLocallyOrStoredToOneGlobal smart enough to see through
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
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 51398b8..91e1296 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -811,7 +811,8 @@
/// 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 @@
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 @@
// 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,