From: Chandler Carruth <chandlerc@gmail.com>
Date: Sat, 27 Sep 2014 08:40:33 +0000 (+0000)
Subject: [x86] Fix yet another issue with widening vector shuffle elements.
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=b66b0cf2ebe25eafbfad7b54ebc96a9b260fb57d

[x86] Fix yet another issue with widening vector shuffle elements.
I spotted this by inspection when debugging something else, so I have no
test case what-so-ever, and am not even sure it is possible to
realistically trigger the bug. But this is what was intended here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218565 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 17f925bd3e8..4678340b6fb 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -9884,11 +9884,11 @@ static bool canWidenShuffleElements(ArrayRef<int> Mask,
 
     // Check for an undef mask and a mask value properly aligned to fit with
     // a pair of values. If we find such a case, use the non-undef mask's value.
-    if (Mask[i] == -1 && Mask[i + 1] % 2 == 1) {
+    if (Mask[i] == -1 && Mask[i + 1] >= 0 && Mask[i + 1] % 2 == 1) {
       WidenedMask.push_back(Mask[i + 1] / 2);
       continue;
     }
-    if (Mask[i + 1] == -1 && Mask[i] % 2 == 0) {
+    if (Mask[i + 1] == -1 && Mask[i] >= 0 && Mask[i] % 2 == 0) {
       WidenedMask.push_back(Mask[i] / 2);
       continue;
     }