2 files changed, 10 insertions, 4 deletions
diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index 3072cee61c..c3d6194801 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -504,11 +504,15 @@ static bool AreEquivalentAddressValues(const Value *A, const Value *B) {
   // Test if the values are trivially equivalent.
   if (A == B) return true;
   
-  // Test if the values come form identical arithmetic instructions.
+  // Test if the values come from identical arithmetic instructions.
+  // Use isIdenticalToWhenDefined instead of isIdenticalTo because
+  // this function is only used when one address use dominates the
+  // other, which means that they'll always either have the same
+  // value or one of them will have an undefined value.
   if (isa<BinaryOperator>(A) || isa<CastInst>(A) ||
       isa<PHINode>(A) || isa<GetElementPtrInst>(A))
     if (const Instruction *BI = dyn_cast<Instruction>(B))
-      if (cast<Instruction>(A)->isIdenticalTo(BI))
+      if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
         return true;
   
   // Otherwise they may not be equivalent.
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 7b7495e665..0938c44c96 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -872,7 +872,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
   while (isa<DbgInfoIntrinsic>(I2))
     I2 = BB2_Itr++;
   if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
-      !I1->isIdenticalTo(I2) ||
+      !I1->isIdenticalToWhenDefined(I2) ||
       (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)))
     return false;
 
@@ -891,6 +891,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
     BIParent->getInstList().splice(BI, BB1->getInstList(), I1);
     if (!I2->use_empty())
       I2->replaceAllUsesWith(I1);
+    I1->intersectOptionalDataWith(I2);
     BB2->getInstList().erase(I2);
 
     I1 = BB1_Itr++;
@@ -899,7 +900,8 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
     I2 = BB2_Itr++;
     while (isa<DbgInfoIntrinsic>(I2))
       I2 = BB2_Itr++;
-  } while (I1->getOpcode() == I2->getOpcode() && I1->isIdenticalTo(I2));
+  } while (I1->getOpcode() == I2->getOpcode() &&
+           I1->isIdenticalToWhenDefined(I2));
 
   return true;