Make this compute the correct offset, handling alignment of the element

pointer correctly.

llvm-svn: 42918

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/include/llvm/ADT/StringMap.h b/llvm/include/llvm/ADT/StringMap.h
index fecd61ead1b..7f8657e5609 100644
--- a/llvm/include/llvm/ADT/StringMap.h
+++ b/llvm/include/llvm/ADT/StringMap.h
@@ -171,8 +171,9 @@ public:
   /// GetStringMapEntryFromValue - Given a value that is known to be embedded
   /// into a StringMapEntry, return the StringMapEntry itself.
   static StringMapEntry &GetStringMapEntryFromValue(ValueTy &V) {
-    return *reinterpret_cast<StringMapEntry*>(reinterpret_cast<char*>(&V) -
-                                              sizeof(StringMapEntryBase));
+    StringMapEntry *EPtr = 0;
+    char *Ptr = reinterpret_cast<char*>(&V) - (intptr_t)&EPtr->Val;
+    return *reinterpret_cast<StringMapEntry*>(Ptr);
   }
   static const StringMapEntry &GetStringMapEntryFromValue(const ValueTy &V) {
     return GetStringMapEntryFromValue(const_cast<ValueTy&>(V));