From 35f92ae3af08e79f60c6d09b38f650a29b1c2cbf Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sun, 17 Oct 2004 04:01:51 +0000
Subject: [PATCH] Fix constant folding relational operators with undef
 operands.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17077 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/ConstantFold.cpp | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index 2e8ed54ec64..b56366ea663 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -830,7 +830,9 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
   // If we successfully folded the expression, return it now.
   if (C) return C;
 
-  if (SetCondInst::isRelational(Opcode))
+  if (SetCondInst::isRelational(Opcode)) {
+    if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
+      return UndefValue::get(Type::BoolTy);
     switch (evaluateRelation(V1, V2)) {
     default: assert(0 && "Unknown relational!");
     case Instruction::BinaryOpsEnd:
@@ -871,17 +873,12 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
       if (Opcode == Instruction::SetNE) return ConstantBool::True;
       break;
     }
+  }
 
   if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
     switch (Opcode) {
     case Instruction::Add:
     case Instruction::Sub:
-    case Instruction::SetEQ:
-    case Instruction::SetNE:
-    case Instruction::SetLT:
-    case Instruction::SetLE:
-    case Instruction::SetGT:
-    case Instruction::SetGE:
     case Instruction::Xor:
       return UndefValue::get(V1->getType());