From 9876ed07f633af7702d4f06de8666a0a48c20fb6 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Thu, 15 Dec 2016 12:12:45 +0000
Subject: [CostModel] Fix long standing bug with reverse shuffle mask detection

Incorrect 'undef' mask index matching meant that broadcast shuffles could be detected as reverse shuffles

llvm-svn: 289811
---
 llvm/lib/Analysis/CostModel.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'llvm/lib/Analysis/CostModel.cpp')

diff --git a/llvm/lib/Analysis/CostModel.cpp b/llvm/lib/Analysis/CostModel.cpp
index 5dd54cd4d19..70b3560808c 100644
--- a/llvm/lib/Analysis/CostModel.cpp
+++ b/llvm/lib/Analysis/CostModel.cpp
@@ -92,7 +92,7 @@ CostModelAnalysis::runOnFunction(Function &F) {
 
 static bool isReverseVectorMask(SmallVectorImpl<int> &Mask) {
   for (unsigned i = 0, MaskSize = Mask.size(); i < MaskSize; ++i)
-    if (Mask[i] > 0 && Mask[i] != (int)(MaskSize - 1 - i))
+    if (Mask[i] >= 0 && Mask[i] != (int)(MaskSize - 1 - i))
       return false;
   return true;
 }
-- 
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