From 300e36503ca6f0599d64d0e5d4705a1030dac6a1 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Wed, 15 Apr 2009 06:23:41 +0000
Subject: [PATCH] Limit the number of times we're willing to chase pointers.
 Removes an O(n^2) problem from instcombine.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69151 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/Value.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp
index 499b936e29c..af3f4e70784 100644
--- a/lib/VMCore/Value.cpp
+++ b/lib/VMCore/Value.cpp
@@ -365,6 +365,7 @@ Value *Value::getUnderlyingObject() {
   if (!isa<PointerType>(getType()))
     return this;
   Value *V = this;
+  unsigned MaxLookup = 6;
   do {
     if (Instruction *I = dyn_cast<Instruction>(V)) {
       if (!isa<BitCastInst>(I) && !isa<GetElementPtrInst>(I))
@@ -379,7 +380,8 @@ Value *Value::getUnderlyingObject() {
       return V;
     }
     assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
-  } while (1);
+  } while (--MaxLookup);
+  return V;
 }
 
 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,