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

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/CodeGen/CGExprAgg.cpp b/lib/CodeGen/CGExprAgg.cpp
index 20722f7799..219a5f9153 100644
--- a/lib/CodeGen/CGExprAgg.cpp
+++ b/lib/CodeGen/CGExprAgg.cpp
@@ -307,6 +307,10 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
     break;
   }
       
+  case CastExpr::CK_LValueBitCast:
+    llvm_unreachable("there are no lvalue bit-casts on aggregates");
+    break;
+      
   case CastExpr::CK_BitCast: {
     // This must be a member function pointer cast.
     Visit(E->getSubExpr());