[CVP] Generate simpler code for elided with.overflow intrinsics

Use a { iN undef, i1 false } struct as the base, and only insert
the first operand, instead of using { iN undef, i1 undef } as the
base and inserting both. This is the same as what we do in InstCombine.

Differential Revision: https://reviews.llvm.org/D67034

llvm-svn: 370573

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 5629debe802..66335ed6ce5 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -417,6 +417,7 @@ static bool willNotOverflow(BinaryOpIntrinsic *BO, LazyValueInfo *LVI) {
   return NWRegion.contains(LRange);
 }
 
+// Rewrite this with.overflow intrinsic as non-overflowing.
 static void processOverflowIntrinsic(WithOverflowInst *WO) {
   IRBuilder<> B(WO);
   Value *NewOp = B.CreateBinOp(
@@ -429,8 +430,11 @@ static void processOverflowIntrinsic(WithOverflowInst *WO) {
       Inst->setHasNoUnsignedWrap();
   }
 
-  Value *NewI = B.CreateInsertValue(UndefValue::get(WO->getType()), NewOp, 0);
-  NewI = B.CreateInsertValue(NewI, ConstantInt::getFalse(WO->getContext()), 1);
+  StructType *ST = cast<StructType>(WO->getType());
+  Constant *Struct = ConstantStruct::get(ST,
+      { UndefValue::get(ST->getElementType(0)),
+        ConstantInt::getFalse(ST->getElementType(1)) });
+  Value *NewI = B.CreateInsertValue(Struct, NewOp, 0);
   WO->replaceAllUsesWith(NewI);
   WO->eraseFromParent();
   ++NumOverflows;