From: Alexey Samsonov <vonosmas@gmail.com>
Date: Thu, 4 Dec 2014 22:45:31 +0000 (+0000)
Subject: Fix UBSan report in StringMap implementation.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8bc006707164952c3b0fc4dcc4f7c3d68e34c4ab;p=oota-llvm.git

Fix UBSan report in StringMap implementation.

Use offsetof() instead of a member access within null pointer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223402 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/ADT/StringMap.h b/include/llvm/ADT/StringMap.h
index 2feb2ab0074..06afe842691 100644
--- a/include/llvm/ADT/StringMap.h
+++ b/include/llvm/ADT/StringMap.h
@@ -182,10 +182,7 @@ public:
   /// GetStringMapEntryFromValue - Given a value that is known to be embedded
   /// into a StringMapEntry, return the StringMapEntry itself.
   static StringMapEntry &GetStringMapEntryFromValue(ValueTy &V) {
-    StringMapEntry *EPtr = 0;
-    char *Ptr = reinterpret_cast<char*>(&V) -
-                  (reinterpret_cast<char*>(&EPtr->second) -
-                   reinterpret_cast<char*>(EPtr));
+    char *Ptr = reinterpret_cast<char *>(&V) - offsetof(StringMapEntry, second);
     return *reinterpret_cast<StringMapEntry*>(Ptr);
   }
   static const StringMapEntry &GetStringMapEntryFromValue(const ValueTy &V) {