MS ABI: Use musttail for vtable thunks that pass arguments by value

This moves some memptr specific code into the generic thunk emission
codepath.

Fixes PR20053.

Reviewers: majnemer

Differential Revision: http://reviews.llvm.org/D4613

llvm-svn: 214004

1 files changed, 93 insertions, 5 deletions

diff --git a/clang/test/CodeGenCXX/microsoft-abi-byval-thunks.cpp b/clang/test/CodeGenCXX/microsoft-abi-byval-thunks.cpp
index 799521725c5..288f3c68ce1 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-byval-thunks.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-byval-thunks.cpp
@@ -1,4 +1,4 @@
-// RUN: not %clang_cc1 %s -fno-rtti -triple=i686-pc-win32 -emit-llvm -o /dev/null 2>&1 | FileCheck --check-prefix=CHECK32 %s
+// RUN: %clang_cc1 %s -fno-rtti -triple=i686-pc-win32 -emit-llvm -o - | FileCheck --check-prefix=CHECK32 %s
 // RUN: %clang_cc1 %s -fno-rtti -triple=x86_64-pc-win32 -emit-llvm -o - | FileCheck --check-prefix=CHECK64 %s
 
 namespace byval_thunk {
@@ -11,15 +11,103 @@ struct Agg {
 
 struct A { virtual void foo(Agg x); };
 struct B { virtual void foo(Agg x); };
-struct C : A, B { virtual void foo(Agg x); };
-C c;
+struct C : A, B { C(); virtual void foo(Agg x); };
+C::C() {} // force emission
 
-// CHECK32: cannot compile this non-trivial argument copy for thunk yet
+// CHECK32-LABEL: define linkonce_odr x86_thiscallcc void @"\01?foo@C@byval_thunk@@W3AEXUAgg@2@@Z"
+// CHECK32:             (%"struct.byval_thunk::C"* %this, <{ %"struct.byval_thunk::Agg" }>* inalloca)
+// CHECK32:   %2 = getelementptr i8* %{{.*}}, i32 -4
+// CHECK32:   musttail call x86_thiscallcc void @"\01?foo@C@byval_thunk@@UAEXUAgg@2@@Z"
+// CHECK32:       (%"struct.byval_thunk::C"* %{{.*}}, <{ %"struct.byval_thunk::Agg" }>* inalloca %0)
+// CHECK32-NEXT: ret void
 
 // CHECK64-LABEL: define linkonce_odr void @"\01?foo@C@byval_thunk@@W7EAAXUAgg@2@@Z"
 // CHECK64:             (%"struct.byval_thunk::C"* %this, %"struct.byval_thunk::Agg"* %x)
 // CHECK64:   getelementptr i8* %{{.*}}, i32 -8
-// CHECK64:   call void @"\01?foo@C@byval_thunk@@UEAAXUAgg@2@@Z"(%"struct.byval_thunk::C"* %{{.*}}, %"struct.byval_thunk::Agg"* %x)
+// CHECK64:   call void @"\01?foo@C@byval_thunk@@UEAAXUAgg@2@@Z"
+// CHECK64:       (%"struct.byval_thunk::C"* %{{.*}}, %"struct.byval_thunk::Agg"* %x)
 // CHECK64-NOT: call
 // CHECK64:   ret void
 }
+
+namespace stdcall_thunk {
+struct Agg {
+  Agg();
+  Agg(const Agg &);
+  ~Agg();
+  int x;
+};
+
+struct A { virtual void __stdcall foo(Agg x); };
+struct B { virtual void __stdcall foo(Agg x); };
+struct C : A, B { C(); virtual void __stdcall foo(Agg x); };
+C::C() {} // force emission
+
+// CHECK32-LABEL: define linkonce_odr x86_stdcallcc void @"\01?foo@C@stdcall_thunk@@W3AGXUAgg@2@@Z"
+// CHECK32:             (<{ %"struct.stdcall_thunk::C"*, %"struct.stdcall_thunk::Agg" }>* inalloca)
+// CHECK32:   %[[this_slot:[^ ]*]] = getelementptr inbounds <{ %"struct.stdcall_thunk::C"*, %"struct.stdcall_thunk::Agg" }>* %0, i32 0, i32 0
+// CHECK32:   load %"struct.stdcall_thunk::C"** %[[this_slot]]
+// CHECK32:   getelementptr i8* %{{.*}}, i32 -4
+// CHECK32:   store %"struct.stdcall_thunk::C"* %{{.*}}, %"struct.stdcall_thunk::C"** %[[this_slot]]
+// CHECK32:   musttail call x86_stdcallcc void @"\01?foo@C@stdcall_thunk@@UAGXUAgg@2@@Z"
+// CHECK32:       (<{ %"struct.stdcall_thunk::C"*, %"struct.stdcall_thunk::Agg" }>*  inalloca %0)
+// CHECK32-NEXT: ret void
+
+// CHECK64-LABEL: define linkonce_odr void @"\01?foo@C@stdcall_thunk@@W7EAAXUAgg@2@@Z"
+// CHECK64:             (%"struct.stdcall_thunk::C"* %this, %"struct.stdcall_thunk::Agg"* %x)
+// CHECK64:   getelementptr i8* %{{.*}}, i32 -8
+// CHECK64:   call void @"\01?foo@C@stdcall_thunk@@UEAAXUAgg@2@@Z"
+// CHECK64:       (%"struct.stdcall_thunk::C"* %{{.*}}, %"struct.stdcall_thunk::Agg"* %x)
+// CHECK64-NOT: call
+// CHECK64:   ret void
+}
+
+namespace sret_thunk {
+struct Agg {
+  Agg();
+  Agg(const Agg &);
+  ~Agg();
+  int x;
+};
+
+struct A { virtual Agg __cdecl foo(Agg x); };
+struct B { virtual Agg __cdecl foo(Agg x); };
+struct C : A, B { C(); virtual Agg __cdecl foo(Agg x); };
+C::C() {} // force emission
+
+// CHECK32-LABEL: define linkonce_odr %"struct.sret_thunk::Agg"* @"\01?foo@C@sret_thunk@@W3AA?AUAgg@2@U32@@Z"
+// CHECK32:             (<{ %"struct.sret_thunk::C"*, %"struct.sret_thunk::Agg"*, %"struct.sret_thunk::Agg" }>* inalloca)
+// CHECK32:   %[[this_slot:[^ ]*]] = getelementptr inbounds <{ %"struct.sret_thunk::C"*, %"struct.sret_thunk::Agg"*, %"struct.sret_thunk::Agg" }>* %0, i32 0, i32 0
+// CHECK32:   load %"struct.sret_thunk::C"** %[[this_slot]]
+// CHECK32:   getelementptr i8* %{{.*}}, i32 -4
+// CHECK32:   store %"struct.sret_thunk::C"* %{{.*}}, %"struct.sret_thunk::C"** %[[this_slot]]
+// CHECK32:   %[[rv:[^ ]*]] = musttail call %"struct.sret_thunk::Agg"* @"\01?foo@C@sret_thunk@@UAA?AUAgg@2@U32@@Z"
+// CHECK32:       (<{ %"struct.sret_thunk::C"*, %"struct.sret_thunk::Agg"*, %"struct.sret_thunk::Agg" }>*  inalloca %0)
+// CHECK32-NEXT: ret %"struct.sret_thunk::Agg"* %[[rv]]
+
+// CHECK64-LABEL: define linkonce_odr void @"\01?foo@C@sret_thunk@@W7EAA?AUAgg@2@U32@@Z"
+// CHECK64:             (%"struct.sret_thunk::C"* %this, %"struct.sret_thunk::Agg"* noalias sret %agg.result, %"struct.sret_thunk::Agg"* %x)
+// CHECK64:   getelementptr i8* %{{.*}}, i32 -8
+// CHECK64:   call void @"\01?foo@C@sret_thunk@@UEAA?AUAgg@2@U32@@Z"
+// CHECK64:       (%"struct.sret_thunk::C"* %{{.*}}, %"struct.sret_thunk::Agg"* sret %agg.result, %"struct.sret_thunk::Agg"* %x)
+// CHECK64-NOT: call
+// CHECK64:   ret void
+}
+
+#if 0
+// FIXME: When we extend LLVM IR to allow forwarding of varargs through musttail
+// calls, use this test.
+namespace variadic_thunk {
+struct Agg {
+  Agg();
+  Agg(const Agg &);
+  ~Agg();
+  int x;
+};
+
+struct A { virtual void foo(Agg x, ...); };
+struct B { virtual void foo(Agg x, ...); };
+struct C : A, B { C(); virtual void foo(Agg x, ...); };
+C::C() {} // force emission
+}
+#endif