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Previously, btf_tag attribute supports record, field, global variable,
function and function parameter ([1]). This patch added support for typedef.
There are two reasons for this addition.
First, to build linux kernel with btf_tag annotated user pointer, we have
#define __user __attribute__((btf_tag("user")))
and the linux kernel contains code like below ([2])
typedef __signalfn_t __user *__sighandler_t;
and the __user attribute applies to typedef type __sighandler_t.
So clang needs to support btf_tag attribute with typedef type
to avoid compilation error.
Second, for typedef of an anonymous struct/union, we can only apply
btf_tag attribute to the anonymous struct/union like below:
typedef struct { ... } __btf_tag target_type
In this case, the __btf_tag attribute applies to anonymous struct,
which increases downstream implementation complexity. But if
typedef with btf_tag attribute is supported, we can have
typedef struct { ... } target_type __btf_tag
which applies __btf_tag to typedef "target_type" which make it
easier to directly associate btf_tag with a named type.
This patch permitted btf_tag with typedef types due to the
above two reasons.
[1] https://reviews.llvm.org/D106614
[2]
https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/signal-defs.h#L82
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D110127
Files:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/test/Misc/pragma-attribute-supported-attributes-list.test
clang/test/Sema/attr-btf_tag.c
Index: clang/test/Sema/attr-btf_tag.c
===================================================================
--- clang/test/Sema/attr-btf_tag.c
+++ clang/test/Sema/attr-btf_tag.c
@@ -25,18 +25,28 @@
enum e1 {
E1
-} __tag1; // expected-error {{'btf_tag' attribute only applies to variables,
functions, structs, unions, classes, and non-static data members}}
+} __tag1; // expected-error {{'btf_tag' attribute only applies to variables,
functions, structs, unions, classes, non-static data members, and typedefs}}
enum e2 {
E2
-} __tag_no_arg; // expected-error {{'btf_tag' attribute only applies to
variables, functions, structs, unions, classes, and non-static data members}}
+} __tag_no_arg; // expected-error {{'btf_tag' attribute only applies to
variables, functions, structs, unions, classes, non-static data members, and
typedefs}}
enum e3 {
E3
-} __tag_2_arg; // expected-error {{'btf_tag' attribute only applies to
variables, functions, structs, unions, classes, and non-static data members}}
+} __tag_2_arg; // expected-error {{'btf_tag' attribute only applies to
variables, functions, structs, unions, classes, non-static data members, and
typedefs}}
int __tag1 __tag2 foo(struct t1 *arg, struct t2 *arg2);
int __tag2 __tag3 foo(struct t1 *arg, struct t2 *arg2);
int __tag1 foo(struct t1 *arg __tag1, struct t2 *arg2) {
return arg->a + arg2->a;
}
+
+typedef unsigned __tag1 * __u1;
+__u1 convert1(long arg) {
+ return (__u1)arg;
+}
+
+typedef struct { int a; int b; } __u2 __tag1;
+__u2 * convert2(long arg) {
+ return (__u2 *)arg;
+}
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -22,7 +22,7 @@
// CHECK-NEXT: Assumption (SubjectMatchRule_function,
SubjectMatchRule_objc_method)
// CHECK-NEXT: Availability ((SubjectMatchRule_record, SubjectMatchRule_enum,
SubjectMatchRule_enum_constant, SubjectMatchRule_field,
SubjectMatchRule_function, SubjectMatchRule_namespace,
SubjectMatchRule_objc_category, SubjectMatchRule_objc_implementation,
SubjectMatchRule_objc_interface, SubjectMatchRule_objc_method,
SubjectMatchRule_objc_property, SubjectMatchRule_objc_protocol,
SubjectMatchRule_record, SubjectMatchRule_type_alias,
SubjectMatchRule_variable))
// CHECK-NEXT: BPFPreserveAccessIndex (SubjectMatchRule_record)
-// CHECK-NEXT: BTFTag (SubjectMatchRule_variable, SubjectMatchRule_function,
SubjectMatchRule_record, SubjectMatchRule_field)
+// CHECK-NEXT: BTFTag (SubjectMatchRule_variable, SubjectMatchRule_function,
SubjectMatchRule_record, SubjectMatchRule_field, SubjectMatchRule_type_alias)
// CHECK-NEXT: BuiltinAlias (SubjectMatchRule_function)
// CHECK-NEXT: CFAuditedTransfer (SubjectMatchRule_function)
// CHECK-NEXT: CFConsumed (SubjectMatchRule_variable_is_parameter)
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -2016,9 +2016,10 @@
let Content = [{
Clang supports the ``__attribute__((btf_tag("ARGUMENT")))`` attribute for all
targets. This attribute may be attached to a struct/union, struct/union field,
-function, function parameter or variable declaration. If -g is specified,
-the ``ARGUMENT`` info will be preserved in IR and be emitted to dwarf.
-For BPF targets, the ``ARGUMENT`` info will be emitted to .BTF ELF section too.
+function, function parameter, variable or typedef declaration. If -g is
+specified, the ``ARGUMENT`` info will be preserved in IR and be emitted to
+dwarf. For BPF targets, the ``ARGUMENT`` info will be emitted to .BTF ELF
+section too.
}];
}
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1838,7 +1838,8 @@
def BTFTag : InheritableAttr {
let Spellings = [Clang<"btf_tag">];
let Args = [StringArgument<"BTFTag">];
- let Subjects = SubjectList<[Var, Function, Record, Field], ErrorDiag>;
+ let Subjects = SubjectList<[Var, Function, Record, Field, TypedefName],
+ ErrorDiag>;
let Documentation = [BTFTagDocs];
let LangOpts = [COnly];
}
Index: clang/test/Sema/attr-btf_tag.c
===================================================================
--- clang/test/Sema/attr-btf_tag.c
+++ clang/test/Sema/attr-btf_tag.c
@@ -25,18 +25,28 @@
enum e1 {
E1
-} __tag1; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+} __tag1; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, non-static data members, and typedefs}}
enum e2 {
E2
-} __tag_no_arg; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+} __tag_no_arg; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, non-static data members, and typedefs}}
enum e3 {
E3
-} __tag_2_arg; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+} __tag_2_arg; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, non-static data members, and typedefs}}
int __tag1 __tag2 foo(struct t1 *arg, struct t2 *arg2);
int __tag2 __tag3 foo(struct t1 *arg, struct t2 *arg2);
int __tag1 foo(struct t1 *arg __tag1, struct t2 *arg2) {
return arg->a + arg2->a;
}
+
+typedef unsigned __tag1 * __u1;
+__u1 convert1(long arg) {
+ return (__u1)arg;
+}
+
+typedef struct { int a; int b; } __u2 __tag1;
+__u2 * convert2(long arg) {
+ return (__u2 *)arg;
+}
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -22,7 +22,7 @@
// CHECK-NEXT: Assumption (SubjectMatchRule_function, SubjectMatchRule_objc_method)
// CHECK-NEXT: Availability ((SubjectMatchRule_record, SubjectMatchRule_enum, SubjectMatchRule_enum_constant, SubjectMatchRule_field, SubjectMatchRule_function, SubjectMatchRule_namespace, SubjectMatchRule_objc_category, SubjectMatchRule_objc_implementation, SubjectMatchRule_objc_interface, SubjectMatchRule_objc_method, SubjectMatchRule_objc_property, SubjectMatchRule_objc_protocol, SubjectMatchRule_record, SubjectMatchRule_type_alias, SubjectMatchRule_variable))
// CHECK-NEXT: BPFPreserveAccessIndex (SubjectMatchRule_record)
-// CHECK-NEXT: BTFTag (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record, SubjectMatchRule_field)
+// CHECK-NEXT: BTFTag (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record, SubjectMatchRule_field, SubjectMatchRule_type_alias)
// CHECK-NEXT: BuiltinAlias (SubjectMatchRule_function)
// CHECK-NEXT: CFAuditedTransfer (SubjectMatchRule_function)
// CHECK-NEXT: CFConsumed (SubjectMatchRule_variable_is_parameter)
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -2016,9 +2016,10 @@
let Content = [{
Clang supports the ``__attribute__((btf_tag("ARGUMENT")))`` attribute for all
targets. This attribute may be attached to a struct/union, struct/union field,
-function, function parameter or variable declaration. If -g is specified,
-the ``ARGUMENT`` info will be preserved in IR and be emitted to dwarf.
-For BPF targets, the ``ARGUMENT`` info will be emitted to .BTF ELF section too.
+function, function parameter, variable or typedef declaration. If -g is
+specified, the ``ARGUMENT`` info will be preserved in IR and be emitted to
+dwarf. For BPF targets, the ``ARGUMENT`` info will be emitted to .BTF ELF
+section too.
}];
}
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1838,7 +1838,8 @@
def BTFTag : InheritableAttr {
let Spellings = [Clang<"btf_tag">];
let Args = [StringArgument<"BTFTag">];
- let Subjects = SubjectList<[Var, Function, Record, Field], ErrorDiag>;
+ let Subjects = SubjectList<[Var, Function, Record, Field, TypedefName],
+ ErrorDiag>;
let Documentation = [BTFTagDocs];
let LangOpts = [COnly];
}
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