commit 309dfefb6f5801968b4bb000b0de01e4c5d6aab2
author Craig Topper <craig.topper@gmail.com> Thu Aug 08 07:38:55 2013 +0000
committer Craig Topper <craig.topper@gmail.com> Thu Aug 08 07:38:55 2013 +0000
tree a8e609e8f751ab6e281681e7be9f6e99ce0331c9
parent 2b7b2f373b7275330da97feaacaeb76342470072

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

llvm-svn: 187961

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cb88941..0d71761 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9358,10 +9358,10 @@
     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);
     }