From: Eli Friedman <eli.friedman@gmail.com>
Date: Thu, 13 Oct 2011 23:48:33 +0000 (+0000)
Subject: Avoid undefined behavior in negation in LSR.  Patch by Ahmed Charles.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=dae36ba802f12966e4fc44d99097a55ff0b7d87b;p=oota-llvm.git

Avoid undefined behavior in negation in LSR.  Patch by Ahmed Charles.

Someone more familiar with LSR should double-check that the extra cast is actually doing the right thing in the overflow cases; I'm not completely confident that's that case.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141916 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index d03b86a7e9d..3e122c2a866 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1205,7 +1205,7 @@ static bool isLegalUse(const TargetLowering::AddrMode &AM,
     // If we have low-level target information, ask the target if it can fold an
     // integer immediate on an icmp.
     if (AM.BaseOffs != 0) {
-      if (TLI) return TLI->isLegalICmpImmediate(-AM.BaseOffs);
+      if (TLI) return TLI->isLegalICmpImmediate(-(uint64_t)AM.BaseOffs);
       return false;
     }
 
@@ -3593,7 +3593,7 @@ Value *LSRInstance::Expand(const LSRFixup &LF,
       // The other interesting way of "folding" with an ICmpZero is to use a
       // negated immediate.
       if (!ICmpScaledV)
-        ICmpScaledV = ConstantInt::get(IntTy, -Offset);
+        ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);
       else {
         Ops.push_back(SE.getUnknown(ICmpScaledV));
         ICmpScaledV = ConstantInt::get(IntTy, Offset);