commit bf55e6dee136d081b0858f62fcc362d74a708894
author Sanjay Patel <spatel@rotateright.com> Mon May 14 13:43:32 2018 +0000
committer Sanjay Patel <spatel@rotateright.com> Mon May 14 13:43:32 2018 +0000
tree f9d4d6d2d7c440cde8fda1711cbc39744cfe3f3e
parent 8f2b2f4e048522b542b5dd948acfc4eca33fd14b

[AggressiveInstCombine] avoid crashing on unsimplified code (PR37446)

This bug:
https://bugs.llvm.org/show_bug.cgi?id=37446
...raises another question: why do we run aggressive-instcombine before 
regular instcombine?

llvm-svn: 332243

llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp

diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
index 16e50c2..cad1731 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
@@ -108,6 +108,10 @@
   if (!MOps.Root)
     MOps.Root = Candidate;
 
+  // The shift constant is out-of-range? This code hasn't been simplified.
+  if (BitIndex >= MOps.Mask.getBitWidth())
+    return false;
+
   // Fill in the mask bit derived from the shift constant.
   MOps.Mask.setBit(BitIndex);
   return MOps.Root == Candidate;