From fafb890ee204d60456d0780ff55a149fa082eaea Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Fri, 23 Apr 2010 01:55:05 +0000
Subject: Fix LSR to tolerate cases where ScalarEvolution initially misses an
 opportunity to fold add operands, but folds them after LSR has separated them
 out. This fixes rdar://7886751.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102157 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LoopStrengthReduce.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'lib/Transforms/Scalar/LoopStrengthReduce.cpp')

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index a09bca8997..a09b3dc5f8 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2060,8 +2060,11 @@ void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,
                            LU.Kind, LU.AccessTy, TLI, SE))
         continue;
 
+      const SCEV *InnerSum = SE.getAddExpr(InnerAddOps);
+      if (InnerSum->isZero())
+        continue;
       Formula F = Base;
-      F.BaseRegs[i] = SE.getAddExpr(InnerAddOps);
+      F.BaseRegs[i] = InnerSum;
       F.BaseRegs.push_back(*J);
       if (InsertFormula(LU, LUIdx, F))
         // If that formula hadn't been seen before, recurse to find more like
-- 
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