From e62fc3d0b6ce923dcbc29eeb6ebc5808e6724f90 Mon Sep 17 00:00:00 2001
From: Matt Morehouse <mascasa@google.com>
Date: Wed, 19 Sep 2018 19:37:24 +0000
Subject: [InstCombine] Disable strcmp->memcmp transform for MSan.

Summary:
The strcmp->memcmp transform can make the resulting memcmp read
uninitialized data, which MSan doesn't like.

Resolves https://github.com/google/sanitizers/issues/993.

Reviewers: eugenis, xbolva00

Reviewed By: eugenis

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D52272

llvm-svn: 342582
---
 llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp')

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 8fa227930b4..3789181a898 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -171,7 +171,10 @@ static bool canTransformToMemCmp(CallInst *CI, Value *Str, uint64_t Len,
 
   if (!isDereferenceableAndAlignedPointer(Str, 1, APInt(64, Len), DL))
     return false;
-    
+
+  if (CI->getFunction()->hasFnAttribute(Attribute::SanitizeMemory))
+    return false;
+
   return true;
 }
 
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