From a376b536951f892bcc31928a7a9cc205d5d9bc1b Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Sat, 29 Jan 2011 03:18:56 +0000
Subject: [PATCH] When doing a derived-to-base class through a virtual class,
 we don't have to get the vbase offset from the vtable if the derived class is
 marked final.

llvm-svn: 124523
---
 clang/lib/CodeGen/CGClass.cpp                    | 13 +++++++++++--
 ...derived-to-virtual-base-class-calls-final.cpp | 16 ++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGenCXX/derived-to-virtual-base-class-calls-final.cpp

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 2a92258b8469..a7b8f659786f 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -180,8 +180,17 @@ CodeGenFunction::GetAddressOfBaseClass(llvm::Value *Value,
 
   llvm::Value *VirtualOffset = 0;
 
-  if (VBase)
-    VirtualOffset = GetVirtualBaseClassOffset(Value, Derived, VBase);
+  if (VBase) {
+    if (Derived->hasAttr<FinalAttr>()) {
+      VirtualOffset = 0;
+
+      const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived);
+
+      uint64_t VBaseOffset = Layout.getVBaseClassOffsetInBits(VBase);
+      NonVirtualOffset += VBaseOffset / 8;
+    } else
+      VirtualOffset = GetVirtualBaseClassOffset(Value, Derived, VBase);
+  }
 
   // Apply the offsets.
   Value = ApplyNonVirtualAndVirtualOffset(*this, Value, NonVirtualOffset, 
diff --git a/clang/test/CodeGenCXX/derived-to-virtual-base-class-calls-final.cpp b/clang/test/CodeGenCXX/derived-to-virtual-base-class-calls-final.cpp
new file mode 100644
index 000000000000..e332f4020001
--- /dev/null
+++ b/clang/test/CodeGenCXX/derived-to-virtual-base-class-calls-final.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
+
+struct A { int i; };
+struct B { int j; };
+struct C : A, B { int k; };
+
+struct D final : virtual C { 
+  D(); 
+  virtual void f();
+};
+
+// CHECK: define %struct.B* @_Z1fR1D
+B &f(D &d) {
+  // CHECK-NOT: load i8**
+  return d;
+}