From 3802c2552fe4475418db3c948e7601d7259f996d Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sun, 11 Dec 2005 09:05:13 +0000
Subject: [PATCH] Minor tweak to get isel opt

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24663 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 23a9954aca2..0630fd37ef0 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1324,7 +1324,8 @@ static void OptimizeGEPExpression(GetElementPtrInst *GEPI,
         break;
       }
   }
-  if (!hasConstantIndex) return;
+  // If this is a GEP &Alloca, 0, 0, forward subst the frame index into uses.
+  if (!hasConstantIndex && !isa<AllocaInst>(GEPI->getOperand(0))) return;
   
   // Otherwise, decompose the GEP instruction into multiplies and adds.  Sum the
   // constant offset (which we now know is non-zero) and deal with it later.