From f38d47144572275396e6e6611fa5e181e79b2944 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 7 Apr 2006 04:44:06 +0000
Subject: [PATCH] Constant fold extractelement(zero, x) -> zero

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27479 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/ConstantFold.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index d63fb6b2db1..94c8651609d 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -836,6 +836,9 @@ Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
                                                       const Constant *Idx) {
   if (isa<UndefValue>(Val))  // ee(undef, x) -> undef
     return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
+  if (Val->isNullValue())  // ee(zero, x) -> zero
+    return Constant::getNullValue(
+                          cast<PackedType>(Val->getType())->getElementType());
   
   if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
     if (const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx)) {