From 1d05be51b09ae1ce65b1ecd6220bade12908586d Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Sat, 13 Feb 2010 21:16:54 +0000
Subject: [PATCH] Don't make return adjustments for pure virtual member
 functions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@96120 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGVtable.cpp          | 13 ++++++++-----
 test/CodeGenCXX/vtable-layout.cpp | 17 +++++++++++++++++
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/lib/CodeGen/CGVtable.cpp b/lib/CodeGen/CGVtable.cpp
index 912f33c5d6..f16f66af2a 100644
--- a/lib/CodeGen/CGVtable.cpp
+++ b/lib/CodeGen/CGVtable.cpp
@@ -426,11 +426,14 @@ void FinalOverriders::PropagateOverrider(const CXXMethodDecl *OldMD,
       assert(Overrider.Method && "Did not find existing overrider!");
 
       // Get the return adjustment base offset.
-      BaseOffset ReturnBaseOffset =
-        ComputeReturnTypeBaseOffset(Context, NewMD, OverriddenMD);
-      if (!ReturnBaseOffset.isEmpty()) {
-        // Store the return adjustment base offset.
-        ReturnAdjustments[SubobjectAndMethod] = ReturnBaseOffset;
+      // (We don't want to do this for pure virtual member functions).
+      if (!NewMD->isPure()) {
+        BaseOffset ReturnBaseOffset =
+          ComputeReturnTypeBaseOffset(Context, NewMD, OverriddenMD);
+        if (!ReturnBaseOffset.isEmpty()) {
+          // Store the return adjustment base offset.
+          ReturnAdjustments[SubobjectAndMethod] = ReturnBaseOffset;
+        }
       }
 
       // Set the new overrider.
diff --git a/test/CodeGenCXX/vtable-layout.cpp b/test/CodeGenCXX/vtable-layout.cpp
index 19ce8da4cf..622983f7c8 100644
--- a/test/CodeGenCXX/vtable-layout.cpp
+++ b/test/CodeGenCXX/vtable-layout.cpp
@@ -182,6 +182,23 @@ struct E : A {
 };
 V3 *E::f() { return 0;}
 
+// Test that a pure virtual member doesn't get a thunk.
+
+// CHECK:     Vtable for 'Test4::F' (5 entries).
+// CHECK-NEXT:   0 | offset_to_top (0)
+// CHECK-NEXT:   1 | Test4::F RTTI
+// CHECK-NEXT:       -- (Test4::A, 0) vtable address --
+// CHECK-NEXT:       -- (Test4::F, 0) vtable address --
+// CHECK-NEXT:   2 | Test4::R3 *Test4::F::f() [pure]
+// CHECK-NEXT:   3 | void Test4::F::g()
+// CHECK-NEXT:   4 | Test4::R3 *Test4::F::f() [pure]
+struct F : A {
+  virtual void g();
+  virtual R3 *f() = 0;
+};
+
+void F::g() { }
+
 }
 
 // For now, just verify this doesn't crash.
-- 
2.40.0