From 157d4ead36ace978a01d80a29aa1b53c832ebafb Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 28 Aug 2010 03:36:51 +0000
Subject: [PATCH] for completeness, allow undef also.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112351 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/InstCombine/InstCombineCasts.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 0434d6ba0fd..6c2477d52c7 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1381,6 +1381,9 @@ static unsigned getTypeSizeIndex(unsigned Value, const Type *Ty) {
 static bool CollectInsertionElements(Value *V, unsigned ElementIndex,
                                      SmallVectorImpl<Value*> &Elements,
                                      const Type *VecEltTy) {
+  // Undef values never contribute useful bits to the result.
+  if (isa<UndefValue>(V)) return true;
+  
   // If we got down to a value of the right type, we win, try inserting into the
   // right element.
   if (V->getType() == VecEltTy) {
-- 
2.34.1