commit 228e6d4cf347820fce53e57c24b266f67a413d85
author Richard Smith <richard-llvm@metafoo.co.uk> Fri Aug 24 23:29:28 2012 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> Fri Aug 24 23:29:28 2012 +0000
tree d2b63a5d9cee710515d33361e84ad0988d2c31fa
parent 3d91b43ad22b69408af224a8d67561038705ec55

Fix integer undefined behavior due to signed left shift overflow in LLVM.
Reviewed offline by chandlerc.

llvm-svn: 162623

llvm/lib/Analysis/ValueTracking.cpp

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index cea34e1..491224a 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1614,7 +1614,7 @@
   // right.
   unsigned PtrSize = TD.getPointerSizeInBits();
   if (PtrSize < 64)
-    Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
+    Offset = SignExtend64(Offset, PtrSize);
   
   return GetPointerBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
 }