From 475ebf5a74c0c5d0faf37b943ac871ad0f5d5677 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Thu, 16 Feb 2012 15:03:04 +0000
Subject: [PATCH] InstSimplify: Strip pointer casts early.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150694 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/InstructionSimplify.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 9d5b74c8cf2..c9ab52c99d1 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1542,6 +1542,10 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
   Type *ITy = GetCompareTy(LHS); // The return type.
   Type *OpTy = LHS->getType();   // The operand type.
 
+  // Remove pointer casts that don't change the value.
+  LHS = LHS->stripPointerCasts();
+  RHS = RHS->stripPointerCasts();
+
   // icmp X, X -> true/false
   // X icmp undef -> true/false.  For example, icmp ugt %X, undef -> false
   // because X could be 0.
@@ -1591,11 +1595,8 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
   // to the case where LHS is a global variable address or null is pointless,
   // since if both LHS and RHS are constants then we already constant folded
   // the compare, and if only one of them is then we moved it to RHS already.
-  Value *LHSPtr = LHS->stripPointerCasts();
-  Value *RHSPtr = RHS->stripPointerCasts();
-  if (isa<AllocaInst>(LHSPtr) && (isa<GlobalValue>(RHSPtr) ||
-                                  isa<AllocaInst>(RHSPtr)  ||
-                                  isa<ConstantPointerNull>(RHSPtr)))
+  if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
+                               isa<ConstantPointerNull>(RHS)))
     // We already know that LHS != RHS.
     return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));