r183095 - Do not walk through member-accesses on bitfields when looking for the object

[Richard Smith]

Author: rsmith
Date: Mon Jun  3 02:13:35 2013
New Revision: 183095

URL: http://llvm.org/viewvc/llvm-project?rev=183095&view=rev
Log:
Do not walk through member-accesses on bitfields when looking for the object
which is lifetime-extended by a reference binding. An additional temporary is
created for such a bitfield access (although we have no explicit AST
representation for it).

Modified:
    cfe/trunk/lib/AST/Expr.cpp
    cfe/trunk/test/CodeGenCXX/temporaries.cpp

Modified: cfe/trunk/lib/AST/Expr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=183095&r1=183094&r2=183095&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Expr.cpp (original)
+++ cfe/trunk/lib/AST/Expr.cpp Mon Jun  3 02:13:35 2013
@@ -76,9 +76,11 @@ const Expr *Expr::skipRValueSubobjectAdj
       if (!ME->isArrow() && ME->getBase()->isRValue()) {
         assert(ME->getBase()->getType()->isRecordType());
         if (FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
-          E = ME->getBase();
-          Adjustments.push_back(SubobjectAdjustment(Field));
-          continue;
+          if (!Field->isBitField()) {
+            E = ME->getBase();
+            Adjustments.push_back(SubobjectAdjustment(Field));
+            continue;
+          }
         }
       }
     } else if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {

Modified: cfe/trunk/test/CodeGenCXX/temporaries.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/temporaries.cpp?rev=183095&r1=183094&r2=183095&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/temporaries.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/temporaries.cpp Mon Jun  3 02:13:35 2013
@@ -604,3 +604,15 @@ namespace BindToSubobject {
   // CHECK: store i32* {{.*}}, i32** @_ZN15BindToSubobject1dE, align 8
   int &&d = (B().a).*h();
 }
+
+namespace Bitfield {
+  struct S { int a : 5; ~S(); };
+
+  // Do not lifetime extend the S() temporary here.
+Â  // CHECK: alloca
+Â  // CHECK: call {{.*}}memset
+Â  // CHECK: store i32 {{.*}}, i32* @_ZGRN8Bitfield1rE, align 4
+  // CHECK: call void @_ZN8Bitfield1SD1
+Â  // CHECK: store i32* @_ZGRN8Bitfield1rE, i32** @_ZN8Bitfield1rE, align 8
+  int &&r = S().a;
+}