[CodeGen] Fix TBAA info for accesses to members of base classes

Resolves:
Bug 35724 - regression (r315984): fatal error: error in backend:
Broken function found (Did not see access type in access path!)
https://bugs.llvm.org/show_bug.cgi?id=35724

Differential Revision: https://reviews.llvm.org/D41547

llvm-svn: 321999

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 3a46bbfe208..73354cdf854 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1034,8 +1034,12 @@ Address CodeGenFunction::EmitPointerWithAlignment(const Expr *E,
     // Derived-to-base conversions.
     case CK_UncheckedDerivedToBase:
     case CK_DerivedToBase: {
-      Address Addr = EmitPointerWithAlignment(CE->getSubExpr(), BaseInfo,
-                                              TBAAInfo);
+      // TODO: Support accesses to members of base classes in TBAA. For now, we
+      // conservatively pretend that the complete object is of the base class
+      // type.
+      if (TBAAInfo)
+        *TBAAInfo = CGM.getTBAAAccessInfo(E->getType());
+      Address Addr = EmitPointerWithAlignment(CE->getSubExpr(), BaseInfo);
       auto Derived = CE->getSubExpr()->getType()->getPointeeCXXRecordDecl();
       return GetAddressOfBaseClass(Addr, Derived,
                                    CE->path_begin(), CE->path_end(),