[clang] b396010 - [Clang] Support typedef with btf_decl_tag attributes

[Yonghong Song via cfe-commits]

Author: Yonghong Song
Date: 2021-10-21T08:41:49-07:00
New Revision: b396010240cda92f5fcfa30cba1b9ad905561eae

URL: https://github.com/llvm/llvm-project/commit/b396010240cda92f5fcfa30cba1b9ad905561eae
DIFF: https://github.com/llvm/llvm-project/commit/b396010240cda92f5fcfa30cba1b9ad905561eae.diff

LOG: [Clang] Support typedef with btf_decl_tag attributes

Previously, btf_del_tag attribute supports record, field, global variable,
function and function parameter ([1], [2]). This patch added support for typedef.
The main reason is for typedef of an anonymous struct/union, we can only apply
btf_decl_tag attribute to the anonymous struct/union like below:
  typedef struct { ... } __btf_decl_tag target_type
In this case, the __btf_decl_tag attribute applies to anonymous struct,
which increases downstream implementation complexity. But if
typedef with btf_decl_tag attribute is supported, we can have
  typedef struct { ... } target_type __btf_decl_tag
which applies __btf_decl_tag to typedef "target_type" which make it
easier to directly associate btf_decl_tag with a named type.
This patch permitted btf_decl_tag with typedef types with this reason.

 [1] https://reviews.llvm.org/D106614
 [2] https://reviews.llvm.org/D111588

Differential Revision: https://reviews.llvm.org/D110127

Added: 
    

Modified: 
    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

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index e94466bd6121a..f58217f8f44ae 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1839,7 +1839,8 @@ def BPFPreserveAccessIndex : InheritableAttr,
 def BTFDeclTag : InheritableAttr {
   let Spellings = [Clang<"btf_decl_tag">];
   let Args = [StringArgument<"BTFDeclTag">];
-  let Subjects = SubjectList<[Var, Function, Record, Field], ErrorDiag>;
+  let Subjects = SubjectList<[Var, Function, Record, Field, TypedefName],
+                             ErrorDiag>;
   let Documentation = [BTFDeclTagDocs];
   let LangOpts = [COnly];
 }

diff  --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 3a70f88eff0a2..71f947687a08f 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -2016,9 +2016,10 @@ def BTFDeclTagDocs : Documentation {
   let Content = [{
 Clang supports the ``__attribute__((btf_decl_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.
+field, 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.
   }];
 }
 

diff  --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index d4cd73f5e9bce..199934b2791da 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/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: BTFDeclTag (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record, SubjectMatchRule_field)
+// CHECK-NEXT: BTFDeclTag (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)

diff  --git a/clang/test/Sema/attr-btf_tag.c b/clang/test/Sema/attr-btf_tag.c
index 4f2a5dd57ad93..d33ccdf962825 100644
--- a/clang/test/Sema/attr-btf_tag.c
+++ b/clang/test/Sema/attr-btf_tag.c
@@ -25,18 +25,26 @@ int i1 __invalid; // expected-error {{'btf_decl_tag' attribute requires a string
 
 enum e1 {
   E1
-} __tag1; // expected-error {{'btf_decl_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+} __tag1; // expected-error {{'btf_decl_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_decl_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+} __tag_no_arg; // expected-error {{'btf_decl_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_decl_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+} __tag_2_arg; // expected-error {{'btf_decl_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 * __u1 __tag1 __tag2;
+typedef struct {
+  int a;
+} __t2 __tag1 __tag2;
+int convert2(__t2 *arg) {
+  return arg->a;
+}