From: Zhou Sheng <zhousheng00@gmail.com>
Date: Fri, 6 Jun 2008 08:32:05 +0000 (+0000)
Subject: As Chris suggested, handle the situation if ShAmt larger than BitWidth,
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=cc41940dff771c98321d601e04e60dc8c67b6e87;p=oota-llvm.git

As Chris suggested, handle the situation if ShAmt larger than BitWidth,
otherwise, opt might crash.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52041 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 05e12692f4c..67c40fe21c9 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1236,7 +1236,7 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
         
       // If the input sign bit is known to be zero, or if none of the top bits
       // are demanded, turn this into an unsigned shift right.
-      if (BitWidth == ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] || 
+      if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] || 
           (HighBits & ~DemandedMask) == HighBits) {
         // Perform the logical shift right.
         Value *NewVal = BinaryOperator::CreateLShr(