From: Craig Topper <craig.topper@gmail.com>
Date: Thu, 8 Aug 2013 07:38:55 +0000 (+0000)
Subject: Optimize mask generation for one of the DAG combiner shufflevector cases.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=01d22aaa78b831ad4837f928e0554be7e65addaa;p=oota-llvm.git

Optimize mask generation for one of the DAG combiner shufflevector cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187961 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cb8894105b1..0d71761fd0f 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9358,10 +9358,10 @@ SDValue DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
     for (unsigned i = 0; i != NumElts; ++i) {
       int Idx = SVN->getMaskElt(i);
       if (Idx >= 0) {
-        if (Idx < (int)NumElts)
-          Idx += NumElts;
-        else
+        if (Idx >= (int)NumElts)
           Idx -= NumElts;
+        else
+          Idx = -1; // remove reference to lhs
       }
       NewMask.push_back(Idx);
     }