PR19668, PR23034: Fix handling of move constructors and deleted copy

constructors when deciding whether classes should be passed indirectly.

This fixes ABI differences between Clang and GCC:

 * Previously, Clang ignored the move constructor when making this
   determination. It now takes the move constructor into account, per
   https://github.com/itanium-cxx-abi/cxx-abi/pull/17 (this change may
   seem recent, but the ABI change was agreed on the Itanium C++ ABI
   list a long time ago).

 * Previously, Clang's behavior when the copy constructor was deleted
   was unstable -- depending on whether the lazy declaration of the
   copy constructor had been triggered, you might get different behavior.
   We now eagerly declare the copy constructor whenever its deletedness
   is unclear, and ignore deleted copy/move constructors when looking for
   a trivial such constructor.

This also fixes an ABI difference between Clang and MSVC:

 * If the copy constructor would be implicitly deleted (but has not been
   lazily declared yet), for instance because the class has an rvalue
   reference member, we would pass it directly. We now pass such a class
   indirectly, matching MSVC.

Based on a patch by Vassil Vassilev, which was based on a patch by Bernd
Schmidt, which was based on a patch by Reid Kleckner!

This is a re-commit of r310401, which was reverted in r310464 due to ARM
failures (which should now be fixed).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310983 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 104 insertions, 33 deletions

diff --git a/test/CodeGenCXX/uncopyable-args.cpp b/test/CodeGenCXX/uncopyable-args.cpp
index 307a5cf11b..ef7168cdaa 100644
--- a/test/CodeGenCXX/uncopyable-args.cpp
+++ b/test/CodeGenCXX/uncopyable-args.cpp
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s | FileCheck %s -check-prefix=WIN64
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s -fms-compatibility -fms-compatibility-version=18 | FileCheck %s -check-prefix=WIN64 -check-prefix=WIN64-18
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-windows-msvc -emit-llvm -o - %s -fms-compatibility -fms-compatibility-version=19 | FileCheck %s -check-prefix=WIN64 -check-prefix=WIN64-19
 
 namespace trivial {
 // Trivial structs should be passed directly.
@@ -52,12 +53,11 @@ void foo(A);
 void bar() {
   foo({});
 }
-// FIXME: The copy ctor is implicitly deleted.
-// CHECK-DISABLED-LABEL: define void @_ZN9move_ctor3barEv()
-// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
-// CHECK-DISABLED-NOT: call
-// CHECK-DISABLED: call void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"* %{{.*}})
-// CHECK-DISABLED-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"*)
+// CHECK-LABEL: define void @_ZN9move_ctor3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT: call
+// CHECK: call void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN9move_ctor3fooENS_1AE(%"struct.move_ctor::A"*)
 
 // WIN64-LABEL: declare void @"\01?foo@move_ctor@@YAXUA@1@@Z"(%"struct.move_ctor::A"*)
 }
@@ -73,12 +73,11 @@ void foo(A);
 void bar() {
   foo({});
 }
-// FIXME: The copy ctor is deleted.
-// CHECK-DISABLED-LABEL: define void @_ZN11all_deleted3barEv()
-// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
-// CHECK-DISABLED-NOT: call
-// CHECK-DISABLED: call void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"* %{{.*}})
-// CHECK-DISABLED-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"*)
+// CHECK-LABEL: define void @_ZN11all_deleted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT: call
+// CHECK: call void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN11all_deleted3fooENS_1AE(%"struct.all_deleted::A"*)
 
 // WIN64-LABEL: declare void @"\01?foo@all_deleted@@YAXUA@1@@Z"(%"struct.all_deleted::A"*)
 }
@@ -93,14 +92,15 @@ void foo(A);
 void bar() {
   foo({});
 }
-// FIXME: The copy and move ctors are implicitly deleted.
-// CHECK-DISABLED-LABEL: define void @_ZN18implicitly_deleted3barEv()
-// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
-// CHECK-DISABLED-NOT: call
-// CHECK-DISABLED: call void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"* %{{.*}})
-// CHECK-DISABLED-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"*)
-
-// WIN64-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(%"struct.implicitly_deleted::A"*)
+// CHECK-LABEL: define void @_ZN18implicitly_deleted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT: call
+// CHECK: call void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN18implicitly_deleted3fooENS_1AE(%"struct.implicitly_deleted::A"*)
+
+// In MSVC 2013, the copy ctor is not deleted by a move assignment. In MSVC 2015, it is.
+// WIN64-18-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(i64
+// WIN64-19-LABEL: declare void @"\01?foo@implicitly_deleted@@YAXUA@1@@Z"(%"struct.implicitly_deleted::A"*)
 }
 
 namespace one_deleted {
@@ -113,12 +113,11 @@ void foo(A);
 void bar() {
   foo({});
 }
-// FIXME: The copy constructor is implicitly deleted.
-// CHECK-DISABLED-LABEL: define void @_ZN11one_deleted3barEv()
-// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
-// CHECK-DISABLED-NOT: call
-// CHECK-DISABLED: call void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"* %{{.*}})
-// CHECK-DISABLED-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"*)
+// CHECK-LABEL: define void @_ZN11one_deleted3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK-NOT: call
+// CHECK: call void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN11one_deleted3fooENS_1AE(%"struct.one_deleted::A"*)
 
 // WIN64-LABEL: declare void @"\01?foo@one_deleted@@YAXUA@1@@Z"(%"struct.one_deleted::A"*)
 }
@@ -195,12 +194,10 @@ void foo(B);
 void bar() {
   foo({});
 }
-// FIXME: This class has a non-trivial copy ctor and a trivial copy ctor.  It's
-// not clear whether we should pass by address or in registers.
-// CHECK-DISABLED-LABEL: define void @_ZN14two_copy_ctors3barEv()
-// CHECK-DISABLED: call void @_Z{{.*}}C1Ev(
-// CHECK-DISABLED: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* %{{.*}})
-// CHECK-DISABLED-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"*)
+// CHECK-LABEL: define void @_ZN14two_copy_ctors3barEv()
+// CHECK: call void @_Z{{.*}}C1Ev(
+// CHECK: call void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"* %{{.*}})
+// CHECK-LABEL: declare void @_ZN14two_copy_ctors3fooENS_1BE(%"struct.two_copy_ctors::B"*)
 
 // WIN64-LABEL: declare void @"\01?foo@two_copy_ctors@@YAXUB@1@@Z"(%"struct.two_copy_ctors::B"*)
 }
@@ -212,6 +209,7 @@ struct A {
   void *p;
 };
 void *foo(A a) { return a.p; }
+// CHECK-LABEL: define i8* @_ZN15definition_only3fooENS_1AE(%"struct.definition_only::A"*
 // WIN64-LABEL: define i8* @"\01?foo@definition_only@@YAPEAXUA@1@@Z"(%"struct.definition_only::A"*
 }
 
@@ -226,6 +224,7 @@ struct A {
   B b;
 };
 void *foo(A a) { return a.b.p; }
+// CHECK-LABEL: define i8* @_ZN17deleted_by_member3fooENS_1AE(%"struct.deleted_by_member::A"*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_member@@YAPEAXUA@1@@Z"(%"struct.deleted_by_member::A"*
 }
 
@@ -239,6 +238,7 @@ struct A : B {
   A();
 };
 void *foo(A a) { return a.p; }
+// CHECK-LABEL: define i8* @_ZN15deleted_by_base3fooENS_1AE(%"struct.deleted_by_base::A"*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_base@@YAPEAXUA@1@@Z"(%"struct.deleted_by_base::A"*
 }
 
@@ -253,6 +253,7 @@ struct A {
   B b;
 };
 void *foo(A a) { return a.b.p; }
+// CHECK-LABEL: define i8* @_ZN22deleted_by_member_copy3fooENS_1AE(%"struct.deleted_by_member_copy::A"*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_member_copy@@YAPEAXUA@1@@Z"(%"struct.deleted_by_member_copy::A"*
 }
 
@@ -266,6 +267,7 @@ struct A : B {
   A();
 };
 void *foo(A a) { return a.p; }
+// CHECK-LABEL: define i8* @_ZN20deleted_by_base_copy3fooENS_1AE(%"struct.deleted_by_base_copy::A"*
 // WIN64-LABEL: define i8* @"\01?foo@deleted_by_base_copy@@YAPEAXUA@1@@Z"(%"struct.deleted_by_base_copy::A"*
 }
 
@@ -275,6 +277,75 @@ struct A {
   A(const A &o) = delete;
   void *p;
 };
+// CHECK-LABEL: define i8* @_ZN15explicit_delete3fooENS_1AE(%"struct.explicit_delete::A"*
 // WIN64-LABEL: define i8* @"\01?foo@explicit_delete@@YAPEAXUA@1@@Z"(%"struct.explicit_delete::A"*
 void *foo(A a) { return a.p; }
 }
+
+namespace implicitly_deleted_copy_ctor {
+struct A {
+  // No move ctor due to copy assignment.
+  A &operator=(const A&);
+  // Deleted copy ctor due to rvalue ref member.
+  int &&ref;
+};
+// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1AE(%"struct.implicitly_deleted_copy_ctor::A"*
+// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAAEAHUA@1@@Z"(%"struct.implicitly_deleted_copy_ctor::A"*
+int &foo(A a) { return a.ref; }
+
+struct B {
+  // Passed direct: has non-deleted trivial copy ctor.
+  B &operator=(const B&);
+  int &ref;
+};
+int &foo(B b) { return b.ref; }
+// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1BE(i32*
+// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAAEAHUB@1@@Z"(i64
+
+struct X { X(const X&); };
+struct Y { Y(const Y&) = default; };
+
+union C {
+  C &operator=(const C&);
+  // Passed indirect: copy ctor deleted due to variant member with nontrivial copy ctor.
+  X x;
+  int n;
+};
+int foo(C c) { return c.n; }
+// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1CE(%"union.implicitly_deleted_copy_ctor::C"*
+// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHTC@1@@Z"(%"union.implicitly_deleted_copy_ctor::C"*
+
+struct D {
+  D &operator=(const D&);
+  // Passed indirect: copy ctor deleted due to variant member with nontrivial copy ctor.
+  union {
+    X x;
+    int n;
+  };
+};
+int foo(D d) { return d.n; }
+// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1DE(%"struct.implicitly_deleted_copy_ctor::D"*
+// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHUD@1@@Z"(%"struct.implicitly_deleted_copy_ctor::D"*
+
+union E {
+  // Passed direct: has non-deleted trivial copy ctor.
+  E &operator=(const E&);
+  Y y;
+  int n;
+};
+int foo(E e) { return e.n; }
+// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1EE(i32
+// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHTE@1@@Z"(i32
+
+struct F {
+  // Passed direct: has non-deleted trivial copy ctor.
+  F &operator=(const F&);
+  union {
+    Y y;
+    int n;
+  };
+};
+int foo(F f) { return f.n; }
+// CHECK-LABEL: define {{.*}} @_ZN28implicitly_deleted_copy_ctor3fooENS_1FE(i32
+// WIN64-LABEL: define {{.*}} @"\01?foo@implicitly_deleted_copy_ctor@@YAHUF@1@@Z"(i32
+}