From 2720248ae5b0201a7bdba57f3625869b578f2a5d Mon Sep 17 00:00:00 2001
From: Michael Kuperstein <michael.m.kuperstein@intel.com>
Date: Mon, 6 May 2013 08:06:13 +0000
Subject: [PATCH] Fix slightly too aggressive conact_vector optimization.
 (Would sometimes optimize away conacts used to extend a vector with undef
 values)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181186 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp         |  6 ++++++
 test/CodeGen/X86/2013-05-06-ConactVectorCrash.ll | 14 ++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 test/CodeGen/X86/2013-05-06-ConactVectorCrash.ll

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 85f5df911db..2e09ec08fdb 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9145,6 +9145,12 @@ SDValue DAGCombiner::visitCONCAT_VECTORS(SDNode *N) {
         return SDValue();
     } else {
       SingleSource = Op.getOperand(0);
+
+      // Check the source type is the same as the type of the result.
+      // If not, this concat may extend the vector, so we can not
+      // optimize it away.
+      if (SingleSource.getValueType() != N->getValueType(0))
+        return SDValue();
     }
 
     unsigned IdentityIndex = i * PartNumElem;
diff --git a/test/CodeGen/X86/2013-05-06-ConactVectorCrash.ll b/test/CodeGen/X86/2013-05-06-ConactVectorCrash.ll
new file mode 100644
index 00000000000..920341799d6
--- /dev/null
+++ b/test/CodeGen/X86/2013-05-06-ConactVectorCrash.ll
@@ -0,0 +1,14 @@
+; RUN: llc < %s -march=x86
+
+; Make sure this doesn't crash
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-win32"
+
+define void @foo() {
+  %1 = shufflevector <3 x i8> undef, <3 x i8> undef, <2 x i32> <i32 0, i32 1>
+  %2 = shufflevector <2 x i8> %1, <2 x i8> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
+  %3 = shufflevector <4 x i8> undef, <4 x i8> %2, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
+  store <4 x i8> %3, <4 x i8>* undef
+  ret void
+}