yonghong-song updated this revision to Diff 363480.
yonghong-song edited the summary of this revision.
yonghong-song added a comment.
address Aaron and Andrii's comments:
- warned and ignored if a btf_tag attribute is added to record forward
declaration.
- warned and ignored if a btf_tag attribute is in a prototype declaration but
that attribute is not in later redeclaration or definition
- added tests to cover the above warn situations and unsupported declaration
like enum
- fixed some missing points and formats in docs.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D106614/new/
https://reviews.llvm.org/D106614
Files:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/Misc/pragma-attribute-supported-attributes-list.test
clang/test/Sema/attr-btf_tag.c
Index: clang/test/Sema/attr-btf_tag.c
===================================================================
--- /dev/null
+++ clang/test/Sema/attr-btf_tag.c
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -x c -triple x86_64-pc-linux-gnu -dwarf-version=4 -fsyntax-only -verify %s
+
+#define __tag __attribute__((btf_tag("tag")))
+#define __tag2 __attribute__((btf_tag("tag2")))
+#define __tag_no_arg __attribute__((btf_tag()))
+#define __tag_2_arg __attribute__((btf_tag("tag1", "tag2")))
+#define __invalid __attribute__((btf_tag(1)))
+
+struct __tag t1; // expected-warning {{attribute 'btf_tag("tag")' in forward declaration ignored}}
+struct t1 {
+ int a __tag;
+} __tag;
+
+int g1 __tag;
+int g2 __tag_no_arg; // expected-error {{'btf_tag' attribute takes one argument}}
+int g3 __tag_2_arg; // expected-error {{'btf_tag' attribute takes one argument}}
+int i1 __invalid; // expected-error {{'btf_tag' attribute requires a string}}
+
+enum e1 {
+ E1
+} __tag; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+
+enum e2 {
+ E2
+} __tag_no_arg; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+
+enum e3 {
+ E3
+} __tag_2_arg; // expected-error {{'btf_tag' attribute only applies to variables, functions, structs, unions, classes, and non-static data members}}
+
+int __tag2 foo(struct t1 *arg); // expected-warning {{attribute 'btf_tag("tag2")' ignored as not in later redeclaration or definition}}
+int __tag foo(struct t1 *arg);
+int __tag foo(struct t1 *arg __tag) {
+ return arg->a;
+}
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
@@ -22,6 +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: BuiltinAlias (SubjectMatchRule_function)
// CHECK-NEXT: CFAuditedTransfer (SubjectMatchRule_function)
// CHECK-NEXT: CFConsumed (SubjectMatchRule_variable_is_parameter)
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -6831,6 +6831,35 @@
Rec->addAttr(::new (S.Context) BPFPreserveAccessIndexAttr(S.Context, AL));
}
+static void handleBTFTagAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+ StringRef Str;
+ if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
+ return;
+
+ // Ignore forward declaration btf_tag attributes.
+ if (auto *Rec = dyn_cast<RecordDecl>(D)) {
+ if (!Rec->isCompleteDefinition()) {
+ S.Diag(AL.getLoc(), diag::warn_btftag_attribute_fwd_decl_ignored) << Str;
+ return;
+ }
+ }
+
+ D->addAttr(::new (S.Context) BTFTagAttr(S.Context, AL, Str));
+}
+
+BTFTagAttr *Sema::mergeBTFTagAttr(Decl *D, const BTFTagAttr &AL) {
+ // Any to-be-merged attribute must be in later redeclaration or actual
+ // definition.
+ for (const auto *I : D->specific_attrs<BTFTagAttr>()) {
+ if (I->getBTFTag() == AL.getBTFTag())
+ return nullptr;
+ }
+
+ Diag(AL.getLoc(), diag::warn_btftag_attribute_conflict_ignored) <<
+ AL.getBTFTag();
+ return nullptr;
+}
+
static void handleWebAssemblyExportNameAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
if (!isFunctionOrMethod(D)) {
S.Diag(D->getLocation(), diag::warn_attribute_wrong_decl_type)
@@ -7868,6 +7897,9 @@
case ParsedAttr::AT_BPFPreserveAccessIndex:
handleBPFPreserveAccessIndexAttr(S, D, AL);
break;
+ case ParsedAttr::AT_BTFTag:
+ handleBTFTagAttr(S, D, AL);
+ break;
case ParsedAttr::AT_WebAssemblyExportName:
handleWebAssemblyExportNameAttr(S, D, AL);
break;
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -2674,6 +2674,8 @@
NewAttr = S.mergeEnforceTCBAttr(D, *TCBA);
else if (const auto *TCBLA = dyn_cast<EnforceTCBLeafAttr>(Attr))
NewAttr = S.mergeEnforceTCBLeafAttr(D, *TCBLA);
+ else if (const auto *BTFA = dyn_cast<BTFTagAttr>(Attr))
+ NewAttr = S.mergeBTFTagAttr(D, *BTFA);
else if (Attr->shouldInheritEvenIfAlreadyPresent() || !DeclHasAttr(D, Attr))
NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -3363,6 +3363,7 @@
EnforceTCBAttr *mergeEnforceTCBAttr(Decl *D, const EnforceTCBAttr &AL);
EnforceTCBLeafAttr *mergeEnforceTCBLeafAttr(Decl *D,
const EnforceTCBLeafAttr &AL);
+ BTFTagAttr *mergeBTFTagAttr(Decl *D, const BTFTagAttr &AL);
void mergeDeclAttributes(NamedDecl *New, Decl *Old,
AvailabilityMergeKind AMK = AMK_Redeclaration);
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -11311,6 +11311,12 @@
"__builtin_preserve_enum_value argument %0 invalid">;
def err_preserve_enum_value_not_const: Error<
"__builtin_preserve_enum_value argument %0 not a constant">;
+def warn_btftag_attribute_fwd_decl_ignored : Warning<
+ "attribute 'btf_tag(\"%0\")' in forward declaration ignored">,
+ InGroup<IgnoredAttributes>;
+def warn_btftag_attribute_conflict_ignored : Warning<
+ "attribute 'btf_tag(\"%0\")' ignored as not in later redeclaration or definition">,
+ InGroup<IgnoredAttributes>;
def err_bit_cast_non_trivially_copyable : Error<
"__builtin_bit_cast %select{source|destination}0 type must be trivially copyable">;
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -2011,6 +2011,16 @@
struct or union, similar to clang ``__builtin_preserve_access_index()``.
}];
}
+def BTFTagDocs : Documentation {
+ let Category = DocCatFunction;
+ 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 argument or variables declaration. If -g is specified,
+the ``ARGUMENT`` info will be preserved in IR and be emitted to dwarf.
+For BPF target, the ``ARGUMENT`` info will be emitted to .BTF ELF section too.
+ }];
+}
def MipsInterruptDocs : Documentation {
let Category = DocCatFunction;
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1835,6 +1835,14 @@
let LangOpts = [COnly];
}
+def BTFTag : InheritableAttr {
+ let Spellings = [Clang<"btf_tag">];
+ let Args = [StringArgument<"BTFTag">];
+ let Subjects = SubjectList<[Var, Function, Record, Field], ErrorDiag>;
+ let Documentation = [BTFTagDocs];
+ let LangOpts = [COnly];
+}
+
def WebAssemblyExportName : InheritableAttr,
TargetSpecificAttr<TargetWebAssembly> {
let Spellings = [Clang<"export_name">];
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