Introduce a new cast kind for an "lvalue bitcast", which handles
reinterpret_casts (possibly indirectly via C-style/functional casts)
on values, e.g., 

  int i;
  reinterpret_cast<short&>(i);

The IR generated for this is essentially the same as for

  *reinterpret_cast<short*>(&i).

Fixes PR6437, PR7593, and PR7344. 



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108294 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 0426a60..5a4808b 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -1816,7 +1816,8 @@
     
     return LValue::MakeAddr(Derived, MakeQualifiers(E->getType()));
   }
-  case CastExpr::CK_BitCast: {
+  case CastExpr::CK_BitCast: 
+  case CastExpr::CK_LValueBitCast: {
     // This must be a reinterpret_cast (or c-style equivalent).
     const ExplicitCastExpr *CE = cast<ExplicitCastExpr>(E);