MS ABI: Update the thunk linkage computation

As suggested by Reid:

 - class has GVA_Internal linkage -> internal
 - thunk has return adjustment -> weak_odr, to handle evil corner case [1]
 - all other normal methods -> linkonce_odr

 1. Evil corner case:

  struct Incomplete;
  struct A { int a; virtual A *bar(); };
  struct B { int b; virtual B *foo(Incomplete); };
  struct C : A, B { int c; virtual C *foo(Incomplete); };
  C c;

Here, the thunk for C::foo() will be emitted when C::foo() is defined, which
might be in a different translation unit, so it needs to be weak_odr.

Differential Revision: http://reviews.llvm.org/D3992

llvm-svn: 210368

5 files changed, 21 insertions, 10 deletions

diff --git a/clang/test/CodeGenCXX/dllimport.cpp b/clang/test/CodeGenCXX/dllimport.cpp
index 004c07e9f63..0295943fdea 100644
--- a/clang/test/CodeGenCXX/dllimport.cpp
+++ b/clang/test/CodeGenCXX/dllimport.cpp
@@ -566,7 +566,7 @@ namespace DontUseDtorAlias {
 
 namespace Vtordisp {
   // Don't dllimport the vtordisp.
-  // MO1-DAG: define weak x86_thiscallcc void @"\01?f@?$C@D@Vtordisp@@$4PPPPPPPM@A@AEXXZ"
+  // MO1-DAG: define linkonce_odr x86_thiscallcc void @"\01?f@?$C@D@Vtordisp@@$4PPPPPPPM@A@AEXXZ"
 
   class Base {
     virtual void f() {}
diff --git a/clang/test/CodeGenCXX/microsoft-abi-structors.cpp b/clang/test/CodeGenCXX/microsoft-abi-structors.cpp
index b79da8d6cb1..04227e311b0 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-structors.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-structors.cpp
@@ -153,7 +153,7 @@ C::~C() {
 void foo() {
   C c;
 }
-// DTORS2-LABEL: define weak x86_thiscallcc void @"\01??_EC@dtor_in_second_nvbase@@W3AEPAXI@Z"
+// DTORS2-LABEL: define linkonce_odr x86_thiscallcc void @"\01??_EC@dtor_in_second_nvbase@@W3AEPAXI@Z"
 // DTORS2:       (%"struct.dtor_in_second_nvbase::C"* %this, i32 %should_call_delete)
 //      Do an adjustment from B* to C*.
 // DTORS2:   getelementptr i8* %{{.*}}, i32 -4
diff --git a/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp b/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
index 2be642c47d0..c755b300067 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
@@ -61,13 +61,13 @@ struct C : A, B {
 
 C::C() {}  // Emits vftable and forces thunk generation.
 
-// CODEGEN-LABEL: define weak x86_thiscallcc void @"\01??_EC@@W3AEPAXI@Z"(%struct.C* %this, i32 %should_call_delete)
+// CODEGEN-LABEL: define linkonce_odr x86_thiscallcc void @"\01??_EC@@W3AEPAXI@Z"(%struct.C* %this, i32 %should_call_delete)
 // CODEGEN:   getelementptr i8* {{.*}}, i32 -4
 // FIXME: should actually call _EC, not _GC.
 // CODEGEN:   call x86_thiscallcc void @"\01??_GC@@UAEPAXI@Z"
 // CODEGEN: ret
 
-// CODEGEN-LABEL: define weak x86_thiscallcc void @"\01?public_f@C@@W3AEXXZ"(%struct.C*
+// CODEGEN-LABEL: define linkonce_odr x86_thiscallcc void @"\01?public_f@C@@W3AEXXZ"(%struct.C*
 // CODEGEN:   getelementptr i8* {{.*}}, i32 -4
 // CODEGEN:   call x86_thiscallcc void @"\01?public_f@C@@UAEXXZ"(%struct.C*
 // CODEGEN: ret
@@ -91,7 +91,7 @@ struct E : D {
 
 E::E() {}  // Emits vftable and forces thunk generation.
 
-// CODEGEN-LABEL: define weak x86_thiscallcc %struct.C* @"\01?goo@E@@QAEPAUB@@XZ"
+// CODEGEN-LABEL: define weak_odr x86_thiscallcc %struct.C* @"\01?goo@E@@QAEPAUB@@XZ"
 // CODEGEN:   call x86_thiscallcc %struct.C* @"\01?goo@E@@UAEPAUC@@XZ"
 // CODEGEN:   getelementptr inbounds i8* {{.*}}, i32 4
 // CODEGEN: ret
@@ -124,7 +124,7 @@ struct I : D {
 
 I::I() {}  // Emits vftable and forces thunk generation.
 
-// CODEGEN-LABEL: define weak x86_thiscallcc %struct.{{[BF]}}* @"\01?goo@I@@QAEPAUB@@XZ"
+// CODEGEN-LABEL: define weak_odr x86_thiscallcc %struct.{{[BF]}}* @"\01?goo@I@@QAEPAUB@@XZ"
 // CODEGEN: %[[ORIG_RET:.*]] = call x86_thiscallcc %struct.F* @"\01?goo@I@@UAEPAUF@@XZ"
 // CODEGEN: %[[ORIG_RET_i8:.*]] = bitcast %struct.F* %[[ORIG_RET]] to i8*
 // CODEGEN: %[[VBPTR_i8:.*]] = getelementptr inbounds i8* %[[ORIG_RET_i8]], i32 4
@@ -152,3 +152,14 @@ struct C : A, B {
 };
 C c;
 }
+
+namespace {
+struct E : D {
+  E();
+  virtual C* goo();
+};
+E::E() {}
+E e;
+// Class with internal linkage has internal linkage thunks.
+// CODEGEN: define internal x86_thiscallcc %struct.C* @"\01?goo@E@?A@@QAEPAUB@@XZ"
+}
diff --git a/clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp b/clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
index 5d118962472..a6fcdea749a 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
@@ -23,7 +23,7 @@ struct D : virtual C {
 
 D::D() {}  // Forces vftable emission.
 
-// CHECK-LABEL: define weak x86_thiscallcc void @"\01?f@D@@$4PPPPPPPM@A@AEXXZ"
+// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPM@A@AEXXZ"
 // CHECK: %[[ECX:.*]] = load %struct.D** %{{.*}}
 // CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
 // CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr i8* %[[ECX_i8]], i32 -4
@@ -34,7 +34,7 @@ D::D() {}  // Forces vftable emission.
 // CHECK: call x86_thiscallcc void @"\01?f@D@@UAEXXZ"(i8* %[[ADJUSTED_i8]])
 // CHECK: ret void
 
-// CHECK-LABEL: define weak x86_thiscallcc void @"\01?f@D@@$4PPPPPPPI@3AEXXZ"
+// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPI@3AEXXZ"
 // CHECK: %[[ECX:.*]] = load %struct.D** %{{.*}}
 // CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
 // CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr i8* %[[ECX_i8]], i32 -8
@@ -63,7 +63,7 @@ struct G : virtual F, virtual E {
 
 G::G() {}  // Forces vftable emission.
 
-// CHECK-LABEL: define weak x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*)
+// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*)
 // CHECK: %[[ECX:.*]] = load %struct.E** %{{.*}}
 // CHECK: %[[ECX_i8:.*]] = bitcast %struct.E* %[[ECX]] to i8*
 // CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr i8* %[[ECX_i8]], i32 -4
diff --git a/clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp b/clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp
index 6ef31769350..4ce4e9c2e17 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp
@@ -145,7 +145,7 @@ struct X: virtual C {
   // MANGLING-DAG: @"\01??_7X@Test4@@6B@"
 
   // Also check the mangling of the thunk.
-  // MANGLING-DAG: define weak x86_thiscallcc void @"\01?f@C@@WPPPPPPPI@AEXXZ"
+  // MANGLING-DAG: define linkonce_odr x86_thiscallcc void @"\01?f@C@@WPPPPPPPI@AEXXZ"
 };
 
 X::X() {}