diff --git a/lib/AST/VTableBuilder.cpp b/lib/AST/VTableBuilder.cpp
index 408fbad17a2342a051ff84f19145ee1b8f636794..b14ddbfe02ea90dab96541336e8295e9526b2dad 100644
--- a/lib/AST/VTableBuilder.cpp
+++ b/lib/AST/VTableBuilder.cpp
@@ -2541,6 +2541,8 @@ private:
}
}
+ bool VFTableBuilder::NeedsReturnAdjustingThunk(const CXXMethodDecl *MD);
+
/// AddMethods - Add the methods of this base subobject and the relevant
/// subbases to the vftable we're currently laying out.
void AddMethods(BaseSubobject Base, unsigned BaseDepth,
@@ -2800,6 +2802,24 @@ static void GroupNewVirtualOverloads(
VirtualMethods.append(Groups[I].rbegin(), Groups[I].rend());
}
+/// We need a return adjusting thunk for this method if its return type is
+/// not trivially convertible to the return type of any of its overridden
+/// methods.
+bool VFTableBuilder::NeedsReturnAdjustingThunk(const CXXMethodDecl *MD) {
+ OverriddenMethodsSetTy OverriddenMethods;
+ ComputeAllOverriddenMethods(MD, OverriddenMethods);
+ for (OverriddenMethodsSetTy::iterator I = OverriddenMethods.begin(),
+ E = OverriddenMethods.end();
+ I != E; ++I) {
+ const CXXMethodDecl *OverriddenMD = *I;
+ BaseOffset Adjustment =
+ ComputeReturnAdjustmentBaseOffset(Context, MD, OverriddenMD);
+ if (!Adjustment.isEmpty())
+ return true;
+ }
+ return false;
+}
+
void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
const CXXRecordDecl *LastVBase,
BasesSetVectorTy &VisitedBases) {
@@ -2885,8 +2905,7 @@ void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
AddThunk(MD, VTableThunks[OverriddenMethodInfo.VFTableIndex]);
}
- if (Context.hasSameType(MD->getResultType(),
- OverriddenMD->getResultType())) {
+ if (!NeedsReturnAdjustingThunk(MD)) {
// No return adjustment needed - just replace the overridden method info
// with the current info.
MethodInfo MI(OverriddenMethodInfo.VBTableIndex,
@@ -3049,6 +3068,8 @@ void VFTableBuilder::dumpLayout(raw_ostream &Out) {
case VTableComponent::CK_FunctionPointer: {
const CXXMethodDecl *MD = Component.getFunctionDecl();
+ // FIXME: Figure out how to print the real thunk type, since they can
+ // differ in the return type.
std::string Str = PredefinedExpr::ComputeName(
PredefinedExpr::PrettyFunctionNoVirtual, MD);
Out << Str;
diff --git a/test/CodeGenCXX/microsoft-abi-vtables-return-thunks.cpp b/test/CodeGenCXX/microsoft-abi-vtables-return-thunks.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..dd7af0aeaf6f5bb9a5768e72eeb4827d7c307cd1
--- /dev/null
+++ b/test/CodeGenCXX/microsoft-abi-vtables-return-thunks.cpp
@@ -0,0 +1,104 @@
+// RUN: %clang_cc1 -fno-rtti %s -emit-llvm -o %t -cxx-abi microsoft -triple=i386-pc-win32 -fdump-vtable-layouts 2>&1 | FileCheck --check-prefix=VFTABLES %s
+// RUN: FileCheck --check-prefix=GLOBALS %s < %t
+// RUN: FileCheck --check-prefix=CODEGEN %s < %t
+
+namespace test1 {
+
+// Some covariant types.
+struct A { int a; };
+struct B { int b; };
+struct C : A, B { int c; };
+struct D : C { int d; };
+struct E : D { int e; };
+
+// One base class and two overrides, all with covariant return types.
+struct H { virtual B *foo(); };
+struct I : H { virtual C *foo(); };
+struct J : I { virtual D *foo(); J(); };
+struct K : J { virtual E *foo(); K(); };
+
+J::J() {}
+
+// VFTABLES-LABEL: VFTable for 'test1::H' in 'test1::I' in 'test1::J' (3 entries).
+// VFTABLES: 0 | test1::D *test1::J::foo()
+// VFTABLES: [return adjustment: 4 non-virtual]
+// VFTABLES: 1 | test1::D *test1::J::foo()
+// VFTABLES: 2 | test1::D *test1::J::foo()
+
+// GLOBALS-LABEL: @"\01??_7J@test1@@6B@" = linkonce_odr unnamed_addr constant [3 x i8*]
+// GLOBALS: @"\01?foo@J@test1@@QAEPAUB@2@XZ"
+// GLOBALS: @"\01?foo@J@test1@@QAEPAUC@2@XZ"
+// GLOBALS: @"\01?foo@J@test1@@QAEPAUD@2@XZ"
+// FIXME: Should be UAEPAUD.
+
+K::K() {}
+
+// VFTABLES-LABEL: VFTable for 'test1::H' in 'test1::I' in 'test1::J' in 'test1::K' (4 entries).
+// VFTABLES: 0 | test1::E *test1::K::foo()
+// VFTABLES: [return adjustment: 4 non-virtual]
+// VFTABLES: 1 | test1::E *test1::K::foo()
+// VFTABLES: 2 | test1::E *test1::K::foo()
+// VFTABLES: 3 | test1::E *test1::K::foo()
+
+// Only B to C requires adjustment, but we get 3 thunks in K's vftable, two of
+// which are trivial.
+// GLOBALS-LABEL: @"\01??_7K@test1@@6B@" = linkonce_odr unnamed_addr constant [4 x i8*]
+// GLOBALS: @"\01?foo@K@test1@@QAEPAUB@2@XZ"
+// GLOBALS: @"\01?foo@K@test1@@QAEPAUC@2@XZ"
+// GLOBALS: @"\01?foo@K@test1@@QAEPAUD@2@XZ"
+// GLOBALS: @"\01?foo@K@test1@@QAEPAUE@2@XZ"
+// FIXME: Should be UAEPAUE.
+
+// This thunk has a return adjustment.
+// CODEGEN-LABEL: define {{.*}} @"\01?foo@K@test1@@QAEPAUB@2@XZ"
+// CODEGEN: call {{.*}} @"\01?foo@K@test1@@UAEPAUE@2@XZ"
+// CODEGEN: icmp {{.*}}, null
+// CODEGEN: getelementptr
+// CODEGEN: ret
+
+// These two don't.
+// CODEGEN-LABEL: define {{.*}} @"\01?foo@K@test1@@QAEPAUC@2@XZ"
+// CODEGEN: call {{.*}} @"\01?foo@K@test1@@UAEPAUE@2@XZ"
+// CODEGEN-NEXT: ret
+
+// CODEGEN-LABEL: define {{.*}} @"\01?foo@K@test1@@QAEPAUD@2@XZ"
+// CODEGEN: call {{.*}} @"\01?foo@K@test1@@UAEPAUE@2@XZ"
+// CODEGEN-NEXT: ret
+
+}
+
+namespace test2 {
+
+// Covariant types. D* is not trivially convertible to C*.
+struct A { int a; };
+struct B { int b; };
+struct C : B { int c; };
+struct D : A, C { int d; };
+struct E : D { int e; };
+
+// J's foo will require an adjusting thunk, and K will require a trivial thunk.
+struct H { virtual B *foo(); };
+struct I : H { virtual C *foo(); };
+struct J : I { virtual D *foo(); J(); };
+struct K : J { virtual E *foo(); K(); };
+
+J::J() {}
+
+// VFTABLES-LABEL: VFTable for 'test2::H' in 'test2::I' in 'test2::J' (2 entries).
+// VFTABLES: 0 | test2::D *test2::J::foo()
+// VFTABLES: [return adjustment: 4 non-virtual]
+// VFTABLES: 1 | test2::D *test2::J::foo()
+
+// GLOBALS-LABEL: @"\01??_7J@test2@@6B@" = linkonce_odr unnamed_addr constant [2 x i8*]
+
+K::K() {}
+
+// VFTABLES-LABEL: VFTable for 'test2::H' in 'test2::I' in 'test2::J' in 'test2::K' (3 entries).
+// VFTABLES: 0 | test2::E *test2::K::foo()
+// VFTABLES: [return adjustment: 4 non-virtual]
+// VFTABLES: 1 | test2::E *test2::K::foo()
+// VFTABLES: 2 | test2::E *test2::K::foo()
+
+// GLOBALS-LABEL: @"\01??_7K@test2@@6B@" = linkonce_odr unnamed_addr constant [3 x i8*]
+
+}
diff --git a/test/CodeGenCXX/microsoft-abi-vtables-single-inheritance.cpp b/test/CodeGenCXX/microsoft-abi-vtables-single-inheritance.cpp
index 3d5cadc718bb2f442758523b07d61f984ade0264..6d0dc1223c5066953f6eed6e7081e6a9cfadf93d 100644
--- a/test/CodeGenCXX/microsoft-abi-vtables-single-inheritance.cpp
+++ b/test/CodeGenCXX/microsoft-abi-vtables-single-inheritance.cpp
@@ -252,12 +252,11 @@ struct N {
N n;
-typedef int int_type;
-struct O { virtual int f(); };
-struct P : O { virtual int_type f(); };
+struct O { virtual A *f(); };
+struct P : O { virtual B *f(); };
P p;
// CHECK-O: VFTable for 'O' in 'P' (1 entries)
-// CHECK-O-NEXT: 0 | int_type P::f()
+// CHECK-O-NEXT: 0 | B *P::f()
// CHECK-O: VFTable for 'O' (1 entries)
-// CHECK-O-NEXT: 0 | int O::f()
+// CHECK-O-NEXT: 0 | A *O::f()