From: Matthias Braun <matze@braunis.de>
Date: Fri, 20 Jan 2017 04:23:08 +0000 (+0000)
Subject: BitVector: Fix undefined behaviour
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=440f273c40cd5a4dbdaf81910c4f5dfc51435bff;p=llvm

BitVector: Fix undefined behaviour

Calling reset() on an empty BitVector would call memset with a nullptr
argument which is undefined behaviour.

This should fix the sanitizer bot.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292575 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/ADT/BitVector.h b/include/llvm/ADT/BitVector.h
index cf3756d0d9c..cb318199ec7 100644
--- a/include/llvm/ADT/BitVector.h
+++ b/include/llvm/ADT/BitVector.h
@@ -539,7 +539,8 @@ private:
   }
 
   void init_words(BitWord *B, unsigned NumWords, bool t) {
-    memset(B, 0 - (int)t, NumWords*sizeof(BitWord));
+    if (NumWords > 0)
+      memset(B, 0 - (int)t, NumWords*sizeof(BitWord));
   }
 
   template<bool AddBits, bool InvertMask>