Address review comments.
- Reword comments.
- Allow undefined behavior interfering with undefined behavior.
- Add address space checks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138619 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index dce4e7a..240f037 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2729,7 +2729,7 @@
if (!C)
return false;
- if (!I->hasOneUse()) // FIXME: There is no reason to limit this to one use.
+ if (!I->hasOneUse()) // Only look at single-use instructions, for compile time
return false;
if (C->isNullValue()) {
@@ -2738,8 +2738,7 @@
// Now make sure that there are no instructions in between that can alter
// control flow (eg. calls)
for (BasicBlock::iterator i = ++BasicBlock::iterator(I); &*i != Use; ++i)
- if (i == I->getParent()->end() ||
- !i->isSafeToSpeculativelyExecute())
+ if (i == I->getParent()->end() || i->mayHaveSideEffects())
return false;
// Look through GEPs. A load from a GEP derived from NULL is still undefined
@@ -2751,13 +2750,13 @@
if (BitCastInst *BC = dyn_cast<BitCastInst>(Use))
return passingValueIsAlwaysUndefined(V, BC);
- // load from null is undefined
- if (isa<LoadInst>(Use))
- return true;
+ // Load from null is undefined.
+ if (LoadInst *LI = dyn_cast<LoadInst>(Use))
+ return LI->getPointerAddressSpace() == 0;
- // store to null is undef
- if (isa<StoreInst>(Use) && Use->getOperand(1) == I)
- return true;
+ // Store to null is undefined.
+ if (StoreInst *SI = dyn_cast<StoreInst>(Use))
+ return SI->getPointerAddressSpace() == 0 && SI->getPointerOperand() == I;
}
return false;
}