From: Duncan Sands <baldrick@free.fr>
Date: Mon, 19 Mar 2012 15:35:44 +0000 (+0000)
Subject: Fix DAG combine which creates illegal vector shuffles.  Patch by Heikki Kultala.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=00294caadb5cdb4cafeb5e1c05486a395fef590c;p=oota-llvm.git

Fix DAG combine which creates illegal vector shuffles.  Patch by Heikki Kultala.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153035 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 32b9fa4ec35..1bd1b95ad7d 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7473,6 +7473,12 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) {
   // Check to see if this is a BUILD_VECTOR of a bunch of EXTRACT_VECTOR_ELT
   // operations.  If so, and if the EXTRACT_VECTOR_ELT vector inputs come from
   // at most two distinct vectors, turn this into a shuffle node.
+
+  // May only combine to shuffle after legalize if shuffle is legal.
+  if (LegalOperations &&
+      !TLI.isOperationLegalOrCustom(ISD::VECTOR_SHUFFLE, VT))
+    return SDValue();
+
   SDValue VecIn1, VecIn2;
   for (unsigned i = 0; i != NumInScalars; ++i) {
     // Ignore undef inputs.