Devirtualize calls on glvalues produced by class member access expressions.

Based on a patch by Yin Ma!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161998 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/CodeGen/CGExprCXX.cpp b/lib/CodeGen/CGExprCXX.cpp
index 7c2c9f1ecb..31ea1b5448 100644
--- a/lib/CodeGen/CGExprCXX.cpp
+++ b/lib/CodeGen/CGExprCXX.cpp
@@ -123,7 +123,14 @@ static bool canDevirtualizeMemberFunctionCalls(ASTContext &Context,
     
     return false;
   }
-  
+
+  // We can devirtualize calls on an object accessed by a class member access
+  // expression, since by C++11 [basic.life]p6 we know that it can't refer to
+  // a derived class object constructed in the same location.
+  if (const MemberExpr *ME = dyn_cast<MemberExpr>(Base))
+    if (const ValueDecl *VD = dyn_cast<ValueDecl>(ME->getMemberDecl()))
+      return VD->getType()->isRecordType();
+
   // We can always devirtualize calls on temporary object expressions.
   if (isa<CXXConstructExpr>(Base))
     return true;