Emit !callback metadata and introduce the callback attribute
With commit r351627, LLVM gained the ability to apply (existing) IPO
optimizations on indirections through callbacks, or transitive calls.
The general idea is that we use an abstraction to hide the middle man
and represent the callback call in the context of the initial caller.
It is described in more detail in the commit message of the LLVM patch
r351627, the llvm::AbstractCallSite class description, and the
language reference section on callback-metadata.
This commit enables clang to emit !callback metadata that is
understood by LLVM. It does so in three different cases:
1) For known broker functions declarations that are directly
generated, e.g., __kmpc_fork_call for the OpenMP pragma parallel.
2) For known broker functions that are identified by their name and
source location through the builtin detection, e.g.,
pthread_create from the POSIX thread API.
3) For user annotated functions that carry the "callback(callee, ...)"
attribute. The attribute has to include the name, or index, of
the callback callee and how the passed arguments can be
identified (as many as the callback callee has). See the callback
attribute documentation for detailed information.
Differential Revision: https://reviews.llvm.org/D55483
llvm-svn: 351629
diff --git a/clang/test/Analysis/retain-release.m b/clang/test/Analysis/retain-release.m
index 5e858f9..81acf0a 100644
--- a/clang/test/Analysis/retain-release.m
+++ b/clang/test/Analysis/retain-release.m
@@ -2,7 +2,7 @@
// RUN: %clang_analyze_cc1 -triple x86_64-apple-darwin10\
// RUN: -analyzer-checker=core,osx.coreFoundation.CFRetainRelease\
// RUN: -analyzer-checker=osx.cocoa.ClassRelease,osx.cocoa.RetainCount\
-// RUN: -analyzer-checker=debug.ExprInspection -fblocks -verify %s\
+// RUN: -analyzer-checker=debug.ExprInspection -fblocks -verify=expected,C %s\
// RUN: -Wno-objc-root-class -analyzer-output=plist -o %t.objc.plist
// RUN: %clang_analyze_cc1 -triple x86_64-apple-darwin10\
// RUN: -analyzer-checker=core,osx.coreFoundation.CFRetainRelease\
@@ -1202,7 +1202,7 @@
typedef unsigned long __darwin_pthread_key_t;
typedef __darwin_pthread_key_t pthread_key_t;
-int pthread_create(pthread_t *, const pthread_attr_t *,
+int pthread_create(pthread_t *, const pthread_attr_t *, // C-warning{{declaration of built-in function 'pthread_create' requires inclusion of the header <pthread.h>}}
void *(*)(void *), void *);
int pthread_setspecific(pthread_key_t key, const void *value);
diff --git a/clang/test/CodeGen/attr-callback.c b/clang/test/CodeGen/attr-callback.c
new file mode 100644
index 0000000..5d96b83
--- /dev/null
+++ b/clang/test/CodeGen/attr-callback.c
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s
+
+void cb0(void);
+
+// CHECK-DAG: !callback ![[cid0:[0-9]+]] void @no_args
+__attribute__((callback(1))) void no_args(void (*callback)(void));
+
+// CHECK-DAG: @args_1({{[^#]*#[0-9]+}} !callback ![[cid1:[0-9]+]]
+__attribute__((callback(1, 2, 3))) void args_1(void (*callback)(int, double), int a, double b) { no_args(cb0); }
+
+// CHECK-DAG: !callback ![[cid2:[0-9]+]] void @args_2a
+__attribute__((callback(2, 3, 3))) void args_2a(int a, void (*callback)(double, double), double b);
+// CHECK-DAG: !callback ![[cid2]] void @args_2b
+__attribute__((callback(callback, b, b))) void args_2b(int a, void (*callback)(double, double), double b);
+
+// CHECK-DAG: void @args_3a({{[^#]*#[0-9]+}} !callback ![[cid3:[0-9]+]]
+__attribute__((callback(2, -1, -1))) void args_3a(int a, void (*callback)(double, double), double b) { args_2a(a, callback, b); }
+// CHECK-DAG: void @args_3b({{[^#]*#[0-9]+}} !callback ![[cid3]]
+__attribute__((callback(callback, __, __))) void args_3b(int a, void (*callback)(double, double), double b) { args_2b(a, callback, b); }
+
+// CHECK-DAG: ![[cid0]] = !{![[cid0b:[0-9]+]]}
+// CHECK-DAG: ![[cid0b]] = !{i64 0, i1 false}
+// CHECK-DAG: ![[cid1]] = !{![[cid1b:[0-9]+]]}
+// CHECK-DAG: ![[cid1b]] = !{i64 0, i64 1, i64 2, i1 false}
+// CHECK-DAG: ![[cid2]] = !{![[cid2b:[0-9]+]]}
+// CHECK-DAG: ![[cid2b]] = !{i64 1, i64 2, i64 2, i1 false}
+// CHECK-DAG: ![[cid3]] = !{![[cid3b:[0-9]+]]}
+// CHECK-DAG: ![[cid3b]] = !{i64 1, i64 -1, i64 -1, i1 false}
diff --git a/clang/test/CodeGen/callback_annotated.c b/clang/test/CodeGen/callback_annotated.c
new file mode 100644
index 0000000..5a4314c
--- /dev/null
+++ b/clang/test/CodeGen/callback_annotated.c
@@ -0,0 +1,73 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fopenmp -O1 %s -emit-llvm -o - | FileCheck %s --check-prefix=RUN1
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fopenmp -O1 %s -emit-llvm -o - | FileCheck %s --check-prefix=RUN2
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fopenmp -O1 %s -emit-llvm -o - | opt -ipconstprop -S | FileCheck --check-prefix=IPCP %s
+
+// RUN1-DAG: @broker0({{[^#]*#[0-9]+}} !callback ![[cid0:[0-9]+]]
+__attribute__((callback(1, 2))) void *broker0(void *(*callee)(void *), void *payload) {
+ return callee(payload);
+}
+
+// RUN1-DAG: @broker1({{[^#]*#[0-9]+}} !callback ![[cid1:[0-9]+]]
+__attribute__((callback(callee, payload))) void *broker1(void *payload, void *(*callee)(void *)) {
+ return broker0(callee, payload);
+}
+
+void *broker2(void (*callee)(void));
+
+// RUN1-DAG: declare !callback ![[cid2:[0-9]+]] i8* @broker2
+__attribute__((callback(callee))) void *broker2(void (*callee)(void));
+
+void *broker2(void (*callee)(void));
+
+// RUN1-DAG: declare !callback ![[cid3:[0-9]+]] i8* @broker3
+__attribute__((callback(4, 1, 2, c))) void *broker3(int, int, int c, int (*callee)(int, int, int), int);
+
+// RUN1-DAG: declare !callback ![[cid4:[0-9]+]] i8* @broker4
+__attribute__((callback(4, -1, a, __))) void *broker4(int a, int, int, int (*callee)(int, int, int), int);
+
+// RUN1-DAG: declare !callback ![[cid5:[0-9]+]] i8* @broker5
+__attribute__((callback(4, d, 5, 2))) void *broker5(int, int, int, int (*callee)(int, int, int), int d);
+
+static void *VoidPtr2VoidPtr(void *payload) {
+ // RUN2: ret i8* %payload
+ // IPCP: ret i8* null
+ return payload;
+}
+
+static int ThreeInt2Int(int a, int b, int c) {
+ // RUN2: define internal i32 @ThreeInt2Int(i32 %a, i32 %b, i32 %c)
+ // RUN2-NEXT: entry:
+ // RUN2-NEXT: %mul = mul nsw i32 %b, %a
+ // RUN2-NEXT: %add = add nsw i32 %mul, %c
+ // RUN2-NEXT: ret i32 %add
+
+ // IPCP: define internal i32 @ThreeInt2Int(i32 %a, i32 %b, i32 %c)
+ // IPCP-NEXT: entry:
+ // IPCP-NEXT: %mul = mul nsw i32 4, %a
+ // IPCP-NEXT: %add = add nsw i32 %mul, %c
+ // IPCP-NEXT: ret i32 %add
+
+ return a * b + c;
+}
+
+void foo() {
+ broker0(VoidPtr2VoidPtr, 0l);
+ broker1(0l, VoidPtr2VoidPtr);
+ broker2(foo);
+ broker3(1, 4, 5, ThreeInt2Int, 1);
+ broker4(4, 2, 7, ThreeInt2Int, 0);
+ broker5(8, 0, 3, ThreeInt2Int, 4);
+}
+
+// RUN1-DAG: ![[cid0]] = !{![[cid0b:[0-9]+]]}
+// RUN1-DAG: ![[cid0b]] = !{i64 0, i64 1, i1 false}
+// RUN1-DAG: ![[cid1]] = !{![[cid1b:[0-9]+]]}
+// RUN1-DAG: ![[cid1b]] = !{i64 1, i64 0, i1 false}
+// RUN1-DAG: ![[cid2]] = !{![[cid2b:[0-9]+]]}
+// RUN1-DAG: ![[cid2b]] = !{i64 0, i1 false}
+// RUN1-DAG: ![[cid3]] = !{![[cid3b:[0-9]+]]}
+// RUN1-DAG: ![[cid3b]] = !{i64 3, i64 0, i64 1, i64 2, i1 false}
+// RUN1-DAG: ![[cid4]] = !{![[cid4b:[0-9]+]]}
+// RUN1-DAG: ![[cid4b]] = !{i64 3, i64 -1, i64 0, i64 -1, i1 false}
+// RUN1-DAG: ![[cid5]] = !{![[cid5b:[0-9]+]]}
+// RUN1-DAG: ![[cid5b]] = !{i64 3, i64 4, i64 4, i64 1, i1 false}
diff --git a/clang/test/CodeGen/callback_openmp.c b/clang/test/CodeGen/callback_openmp.c
new file mode 100644
index 0000000..2fc9dcd
--- /dev/null
+++ b/clang/test/CodeGen/callback_openmp.c
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fopenmp -O1 %s -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fopenmp -O1 %s -emit-llvm -o - | opt -ipconstprop -S | FileCheck --check-prefix=IPCP %s
+
+// CHECK: declare !callback ![[cid:[0-9]+]] void @__kmpc_fork_call
+// CHECK: declare !callback ![[cid]] void @__kmpc_fork_teams
+// CHECK: ![[cid]] = !{![[cidb:[0-9]+]]}
+// CHECK: ![[cidb]] = !{i64 2, i64 -1, i64 -1, i1 true}
+
+void work1(int, int);
+void work2(int, int);
+void work12(int, int);
+
+void foo(int q) {
+ int p = 2;
+
+ #pragma omp parallel firstprivate(q, p)
+ work1(p, q);
+// IPCP: call void @work1(i32 2, i32 %{{[._a-zA-Z0-9]*}})
+
+ #pragma omp parallel for firstprivate(p, q)
+ for (int i = 0; i < q; i++)
+ work2(i, p);
+// IPCP: call void @work2(i32 %{{[._a-zA-Z0-9]*}}, i32 2)
+
+ #pragma omp target teams firstprivate(p)
+ work12(p, p);
+// IPCP: call void @work12(i32 2, i32 2)
+}
diff --git a/clang/test/CodeGen/callback_pthread_create.c b/clang/test/CodeGen/callback_pthread_create.c
new file mode 100644
index 0000000..d751e8a
--- /dev/null
+++ b/clang/test/CodeGen/callback_pthread_create.c
@@ -0,0 +1,32 @@
+// RUN: %clang -O1 %s -S -c -emit-llvm -o - | FileCheck %s
+// RUN: %clang -O1 %s -S -c -emit-llvm -o - | opt -ipconstprop -S | FileCheck --check-prefix=IPCP %s
+
+// CHECK: declare !callback ![[cid:[0-9]+]] dso_local i32 @pthread_create
+// CHECK: ![[cid]] = !{![[cidb:[0-9]+]]}
+// CHECK: ![[cidb]] = !{i64 2, i64 3, i1 false}
+
+#include <pthread.h>
+
+const int GlobalVar = 0;
+
+static void *callee0(void *payload) {
+// IPCP: define internal i8* @callee0
+// IPCP-NEXT: entry:
+// IPCP-NEXT: ret i8* null
+ return payload;
+}
+
+static void *callee1(void *payload) {
+// IPCP: define internal i8* @callee1
+// IPCP-NEXT: entry:
+// IPCP-NEXT: ret i8* bitcast (i32* @GlobalVar to i8*)
+ return payload;
+}
+
+void foo() {
+ pthread_t MyFirstThread;
+ pthread_create(&MyFirstThread, NULL, callee0, NULL);
+
+ pthread_t MySecondThread;
+ pthread_create(&MySecondThread, NULL, callee1, (void *)&GlobalVar);
+}
diff --git a/clang/test/CodeGenCXX/attr-callback.cpp b/clang/test/CodeGenCXX/attr-callback.cpp
new file mode 100644
index 0000000..a05b640
--- /dev/null
+++ b/clang/test/CodeGenCXX/attr-callback.cpp
@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s
+
+struct Base {
+
+ void no_args_1(void (*callback)(void));
+ __attribute__((callback(1))) void no_args_2(void (*callback1)(void), void (*callback2)(void));
+ __attribute__((callback(callback1))) void no_args_3(void (*callback1)(void), void (*callback2)(void));
+
+ // TODO: There should probably be a warning or even an error for different
+ // callbacks on the same method.
+ __attribute__((callback(1))) virtual void
+ virtual_1(void (*callback)(void));
+
+ __attribute__((callback(callback, this, __, this))) virtual void
+ this_unknown_this(void (*callback)(Base *, Base *, Base *));
+};
+
+// CHECK-DAG: define void @_ZN4Base9no_args_1EPFvvE({{[^!]*!callback}} ![[cid0:[0-9]+]]
+__attribute__((callback(1))) void
+Base::no_args_1(void (*callback)(void)) {
+}
+
+// CHECK-DAG: define void @_ZN4Base9no_args_2EPFvvES1_({{[^!]*!callback}} ![[cid1:[0-9]+]]
+__attribute__((callback(2))) void Base::no_args_2(void (*callback1)(void), void (*callback2)(void)) {
+}
+// CHECK-DAG: define void @_ZN4Base9no_args_3EPFvvES1_({{[^!]*!callback}} ![[cid1]]
+__attribute__((callback(callback2))) void Base::no_args_3(void (*callback1)(void), void (*callback2)(void)) {
+}
+
+// CHECK-DAG: define void @_ZN4Base17this_unknown_thisEPFvPS_S0_S0_E({{[^!]*!callback}} ![[cid2:[0-9]+]]
+void Base::this_unknown_this(void (*callback)(Base *, Base *, Base *)) {
+}
+
+struct Derived_1 : public Base {
+ __attribute__((callback(1))) virtual void
+ virtual_1(void (*callback)(void)) override;
+};
+
+// CHECK-DAG: define void @_ZN9Derived_19virtual_1EPFvvE({{[^!]*!callback}} ![[cid0]]
+void Derived_1::virtual_1(void (*callback)(void)) {}
+
+struct Derived_2 : public Base {
+ void virtual_1(void (*callback)(void)) override;
+};
+
+// CHECK-DAG: define void @_ZN9Derived_29virtual_1EPFvvE
+// CHECK-NOT: !callback
+void Derived_2::virtual_1(void (*callback)(void)) {}
+
+// CHECK-DAG: ![[cid0]] = !{![[cid0b:[0-9]+]]}
+// CHECK-DAG: ![[cid0b]] = !{i64 1, i1 false}
+// CHECK-DAG: ![[cid1]] = !{![[cid1b:[0-9]+]]}
+// CHECK-DAG: ![[cid1b]] = !{i64 2, i1 false}
+// CHECK-DAG: ![[cid2]] = !{![[cid2b:[0-9]+]]}
+// CHECK-DAG: ![[cid2b]] = !{i64 1, i64 0, i64 -1, i64 0, i1 false}
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index 9dec259f..e0c0745 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -32,6 +32,7 @@
// CHECK-NEXT: CUDAShared (SubjectMatchRule_variable)
// CHECK-NEXT: CXX11NoReturn (SubjectMatchRule_function)
// CHECK-NEXT: CallableWhen (SubjectMatchRule_function_is_member)
+// CHECK-NEXT: Callback (SubjectMatchRule_function)
// CHECK-NEXT: Capability (SubjectMatchRule_record, SubjectMatchRule_type_alias)
// CHECK-NEXT: CarriesDependency (SubjectMatchRule_variable_is_parameter, SubjectMatchRule_objc_method, SubjectMatchRule_function)
// CHECK-NEXT: Cold (SubjectMatchRule_function)
diff --git a/clang/test/OpenMP/parallel_codegen.cpp b/clang/test/OpenMP/parallel_codegen.cpp
index 19eebc8..ae117a0 100644
--- a/clang/test/OpenMP/parallel_codegen.cpp
+++ b/clang/test/OpenMP/parallel_codegen.cpp
@@ -82,9 +82,9 @@
// CHECK-DEBUG-NEXT: }
// CHECK-DAG: define linkonce_odr {{.*}}void [[FOO]]({{i32[ ]?[a-z]*}} %argc)
-// CHECK-DAG: declare {{.*}}void @__kmpc_fork_call(%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...)
+// CHECK-DAG: declare !callback ![[cbid:[0-9]+]] {{.*}}void @__kmpc_fork_call(%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...)
// CHECK-DEBUG-DAG: define linkonce_odr void [[FOO]](i32 %argc)
-// CHECK-DEBUG-DAG: declare void @__kmpc_fork_call(%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...)
+// CHECK-DEBUG-DAG: declare !callback ![[cbid:[0-9]+]] void @__kmpc_fork_call(%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...)
// CHECK-DEBUG-DAG: define internal void [[OMP_OUTLINED]](i32* noalias %.global_tid., i32* noalias %.bound_tid., i64 [[VLA_SIZE:%.+]], i32* {{.+}} [[VLA_ADDR:%[^)]+]])
// CHECK-DEBUG-DAG: call void [[OMP_OUTLINED_DEBUG]]
@@ -131,5 +131,6 @@
// CHECK: attributes #[[FN_ATTRS]] = {{.+}} nounwind
// CHECK-DEBUG: attributes #[[FN_ATTRS]] = {{.+}} nounwind
-
+// CHECK: ![[cbid]] = !{![[cbidb:[0-9]+]]}
+// CHECK: ![[cbidb]] = !{i64 2, i64 -1, i64 -1, i1 true}
#endif
diff --git a/clang/test/Sema/attr-callback-broken.c b/clang/test/Sema/attr-callback-broken.c
new file mode 100644
index 0000000..b9e5f45
--- /dev/null
+++ b/clang/test/Sema/attr-callback-broken.c
@@ -0,0 +1,75 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+__attribute__((callback())) void no_callee(void (*callback)(void)); // expected-error {{'callback' attribute specifies no callback callee}}
+
+__attribute__((callback(1, 1))) void too_many_args_1(void (*callback)(void)) {} // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(1, -1))) void too_many_args_2(double (*callback)(void)); // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(1, 2, 2))) void too_many_args_3(void (*callback)(int), int); // expected-error {{'callback' attribute requires exactly 2 arguments}}
+
+__attribute__((callback(1, 2))) void too_few_args_1(void (*callback)(int, int), int); // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(1))) void too_few_args_2(int (*callback)(int)); // expected-error {{'callback' attribute takes no arguments}}
+__attribute__((callback(1, -1))) void too_few_args_3(void (*callback)(int, int)) {} // expected-error {{'callback' attribute takes one argument}}
+
+__attribute__((callback(-1))) void oob_args_1(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+__attribute__((callback(2))) void oob_args_2(int *(*callback)(void)) {} // expected-error {{'callback' attribute parameter 1 is out of bounds}}
+__attribute__((callback(1, 3))) void oob_args_3(short (*callback)(int), int); // expected-error {{'callback' attribute parameter 2 is out of bounds}}
+__attribute__((callback(-2, 2))) void oob_args_4(void *(*callback)(int), int); // expected-error {{'callback' attribute parameter 1 is out of bounds}}
+__attribute__((callback(1, -2))) void oob_args_5(void *(*callback)(int), int); // expected-error {{'callback' attribute parameter 2 is out of bounds}}
+__attribute__((callback(1, 2))) void oob_args_6(void *(*callback)(int), ...); // expected-error {{'callback' attribute parameter 2 is out of bounds}}
+
+__attribute__((callback(1))) __attribute__((callback(1))) void multiple_cb_1(void (*callback)(void)); // expected-error {{multiple 'callback' attributes specified}}
+__attribute__((callback(1))) __attribute__((callback(2))) void multiple_cb_2(void (*callback1)(void), void (*callback2)(void)); // expected-error {{multiple 'callback' attributes specified}}
+
+#ifdef HAS_THIS
+__attribute__((callback(0))) void oob_args_0(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+#else
+__attribute__((callback(0))) void oob_args_0(void (*callback)(void)); // expected-error {{'callback' argument at position 1 references unavailable implicit 'this'}}
+__attribute__((callback(1, 0))) void no_this_1(void *(*callback)(void *)); // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+__attribute__((callback(1, 0))) void no_this_2(void *(*callback)(int, void *)); // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+#endif
+
+// We could allow the following declarations if we at some point need to:
+
+__attribute__((callback(1, -1))) void vararg_cb_1(void (*callback)(int, ...)) {} // expected-error {{'callback' attribute callee may not be variadic}}
+__attribute__((callback(1, 1))) void vararg_cb_2(void (*callback)(int, ...), int a); // expected-error {{'callback' attribute callee may not be variadic}}
+
+__attribute__((callback(1, -1, 1, 2, 3, 4, -1))) void varargs_1(void (*callback)(int, ...), int a, float b, double c) {} // expected-error {{'callback' attribute requires exactly 6 arguments}}
+__attribute__((callback(1, -1, 4, 2, 3, 4, -1))) void varargs_2(void (*callback)(void *, double, int, ...), int a, float b, double c); // expected-error {{'callback' attribute requires exactly 6 arguments}}
+
+__attribute__((callback(1, -1, 1))) void self_arg_1(void (*callback)(int, ...)) {} // expected-error {{'callback' attribute requires exactly 2 arguments}}
+__attribute__((callback(1, -1, 1, -1, -1, 1))) void self_arg_2(void (*callback)(int, ...)); // expected-error {{'callback' attribute requires exactly 5 arguments}}
+
+__attribute__((callback(cb))) void unknown_name1(void (*callback)(void)) {} // expected-error {{'callback' attribute argument 'cb' is not a known function parameter}}
+__attribute__((callback(cb, ab))) void unknown_name2(void (*cb)(int), int a) {} // expected-error {{'callback' attribute argument 'ab' is not a known function parameter}}
+
+__attribute__((callback(callback, 1))) void too_many_args_1b(void (*callback)(void)) {} // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(callback, __))) void too_many_args_2b(double (*callback)(void)); // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(callback, 2, 2))) void too_many_args_3b(void (*callback)(int), int); // expected-error {{'callback' attribute requires exactly 2 arguments}}
+
+__attribute__((callback(callback, a))) void too_few_args_1b(void (*callback)(int, int), int a); // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(callback))) void too_few_args_2b(int (*callback)(int)); // expected-error {{'callback' attribute takes no arguments}}
+__attribute__((callback(callback, __))) void too_few_args_3b(void (*callback)(int, int)) {} // expected-error {{'callback' attribute takes one argument}}
+
+__attribute__((callback(__))) void oob_args_1b(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+
+__attribute__((callback(callback))) __attribute__((callback(callback))) void multiple_cb_1b(void (*callback)(void)); // expected-error {{multiple 'callback' attributes specified}}
+__attribute__((callback(1))) __attribute__((callback(callback2))) void multiple_cb_2b(void (*callback1)(void), void (*callback2)(void)); // expected-error {{multiple 'callback' attributes specified}}
+
+#ifdef HAS_THIS
+__attribute__((callback(this))) void oob_args_0b(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+#else
+__attribute__((callback(this))) void oob_args_0b(void (*callback)(void)); // expected-error {{'callback' argument at position 1 references unavailable implicit 'this'}}
+__attribute__((callback(1, this))) void no_this_1b(void *(*callback)(void *)); // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+__attribute__((callback(1, this))) void no_this_2b(void *(*callback)(int, void *)); // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+#endif
+
+// We could allow the following declarations if we at some point need to:
+
+__attribute__((callback(callback, __))) void vararg_cb_1b(void (*callback)(int, ...)) {} // expected-error {{'callback' attribute callee may not be variadic}}
+__attribute__((callback(1, a))) void vararg_cb_2b(void (*callback)(int, ...), int a); // expected-error {{'callback' attribute callee may not be variadic}}
+
+__attribute__((callback(callback, __, callback, a, b, c, __))) void varargs_1b(void (*callback)(int, ...), int a, float b, double c) {} // expected-error {{'callback' attribute requires exactly 6 arguments}}
+__attribute__((callback(1, __, c, a, b, c, -1))) void varargs_2b(void (*callback)(void *, double, int, ...), int a, float b, double c); // expected-error {{'callback' attribute requires exactly 6 arguments}}
+
+__attribute__((callback(1, __, callback))) void self_arg_1b(void (*callback)(int, ...)) {} // expected-error {{'callback' attribute requires exactly 2 arguments}}
+__attribute__((callback(callback, __, callback, __, __, callback))) void self_arg_2b(void (*callback)(int, ...)); // expected-error {{'callback' attribute requires exactly 5 arguments}}
diff --git a/clang/test/Sema/attr-callback.c b/clang/test/Sema/attr-callback.c
new file mode 100644
index 0000000..ec12b16
--- /dev/null
+++ b/clang/test/Sema/attr-callback.c
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+// expected-no-diagnostics
+
+__attribute__((callback(1))) void no_args(void (*callback)(void));
+__attribute__((callback(1, 2, 3))) void args_1(void (*callback)(int, double), int a, double b);
+__attribute__((callback(2, 3, 3))) void args_2(int a, void (*callback)(double, double), double b);
+__attribute__((callback(2, -1, -1))) void args_3(int a, void (*callback)(double, double), double b);
+
+__attribute__((callback(callback))) void no_argsb(void (*callback)(void));
+__attribute__((callback(callback, a, 3))) void args_1b(void (*callback)(int, double), int a, double b);
+__attribute__((callback(callback, b, b))) void args_2b(int a, void (*callback)(double, double), double b);
+__attribute__((callback(2, __, __))) void args_3b(int a, void (*callback)(double, double), double b);
+__attribute__((callback(callback, -1, __))) void args_3c(int a, void (*callback)(double, double), double b);
diff --git a/clang/test/SemaCXX/attr-callback-broken.cpp b/clang/test/SemaCXX/attr-callback-broken.cpp
new file mode 100644
index 0000000..a5469b2
--- /dev/null
+++ b/clang/test/SemaCXX/attr-callback-broken.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+class C_in_class {
+#define HAS_THIS
+#include "../Sema/attr-callback-broken.c"
+#undef HAS_THIS
+};
diff --git a/clang/test/SemaCXX/attr-callback.cpp b/clang/test/SemaCXX/attr-callback.cpp
new file mode 100644
index 0000000..ee02f7d
--- /dev/null
+++ b/clang/test/SemaCXX/attr-callback.cpp
@@ -0,0 +1,67 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+// expected-no-diagnostics
+
+class C_in_class {
+#include "../Sema/attr-callback.c"
+};
+
+struct Base {
+
+ void no_args_1(void (*callback)(void));
+ __attribute__((callback(1))) void no_args_2(void (*callback)(void));
+ __attribute__((callback(callback))) void no_args_3(void (*callback)(void)) {}
+
+ __attribute__((callback(1, 0))) virtual void
+ this_tr(void (*callback)(Base *));
+
+ __attribute__((callback(1, this, __, this))) virtual void
+ this_unknown_this(void (*callback)(Base *, Base *, Base *));
+
+ __attribute__((callback(1))) virtual void
+ virtual_1(void (*callback)(void));
+
+ __attribute__((callback(callback))) virtual void
+ virtual_2(void (*callback)(void));
+
+ __attribute__((callback(1))) virtual void
+ virtual_3(void (*callback)(void));
+};
+
+__attribute__((callback(1))) void
+Base::no_args_1(void (*callback)(void)) {
+}
+
+void Base::no_args_2(void (*callback)(void)) {
+}
+
+struct Derived_1 : public Base {
+
+ __attribute__((callback(1, 0))) virtual void
+ this_tr(void (*callback)(Base *)) override;
+
+ __attribute__((callback(1))) virtual void
+ virtual_1(void (*callback)(void)) override {}
+
+ virtual void
+ virtual_3(void (*callback)(void)) override {}
+};
+
+struct Derived_2 : public Base {
+
+ __attribute__((callback(callback))) virtual void
+ virtual_1(void (*callback)(void)) override;
+
+ virtual void
+ virtual_2(void (*callback)(void)) override;
+
+ virtual void
+ virtual_3(void (*callback)(void)) override;
+};
+
+void Derived_2::virtual_1(void (*callback)(void)) {}
+
+__attribute__((callback(1))) void
+Derived_2::virtual_2(void (*callback)(void)) {}
+
+void Derived_2::virtual_3(void (*callback)(void)) {}