Re: [PATCH 1/3] Add the callback_only attribute.

On Mon, Jul 27, 2026 at 10:43 PM Josef Melcr <[email protected]> wrote:
>
> Changes since v4:
>  - Implemented Jakub's suggestions.
>    - The attribute is now available outside of the gnu namespace with
>      the __attribute__ syntax.
>    - Moved the attribute handler to c-family/c-attribs.cc.
>    - Removed the CALLBACK_ATTR_IDENT macro.
>
> I decided to update the names of identifiers, attribute lists and other
> things to keep things consistent with the new name.
>
> I moved the get_nth_list_elem to c-attribs.cc together with the
> attribute handler, but it will be removed by the next patch.  I decided
> to keep it in this patch solely to preserve the build, as I didn't want
> to make any changes to the functions being moved.
>
> Best regards,
> Josef
>
> gcc/ChangeLog:
>
>         * attr-callback.cc (callback_build_attr): Use "callback_only"
>         instead of the macro.
>         (callback_edge_callee_has_attr): Likewise.
>         (callback_fetch_attr_by_edge): Likewise.
>         (get_nth_list_elem): Move to c-family/c-attribs.cc.
>         (handle_callback_attribute): Rename to
>         handle_callback_only_attribute, move to c-family/c-attribs.cc.
>         * attr-callback.h (CALLBACK_ATTR_IDENT): Remove the macro.
>         (handle_callback_attribute): Remove the declaration.
>         * builtin-attrs.def (ATTR_CALLBACK): Rename to
>         ATTR_CALLBACK_ONLY.
>         (ATTR_CALLBACK_ONLY): Identifier for the attribute for builtins.
>         (DEF_CALLBACK_ATTRIBUTE): Rename to DEF_CALLBACK_ONLY_ATTRIBUTE.
>         (DEF_CALLBACK_ONLY_ATTRIBUTE): Renamed definition macro for builtins.
>         (GOMP): Use the renamed macro.
>         (ATTR_CALLBACK_GOMP_LIST): Renamed to
>         ATTR_CALLBACK_ONLY_GOMP_LIST.
>         (ATTR_CALLBACK_ONLY_GOMP_LIST): ATTR_NOTHROW_LIST with the
>         callback_only attribute for libgomp functions.
>         * cgraph.cc (cgraph_edge::redirect_call_stmt_to_callee): Use
>         "callback_only" instead of the macro.
>         (cgraph_node::verify_node): Likewise.
>         * doc/extend.texi: Add callback_only attribute docs.
>         * ipa-cp.cc (purge_useless_callback_edges): Use "callback_only"
>         instead of the macro.
>         * ipa-param-manipulation.cc
>         (drop_decl_attribute_if_params_changed_p): Likewise.
>         * ipa-prop.cc (ipa_compute_jump_functions_for_edge): Likewise.
>         * omp-builtins.def (BUILT_IN_GOMP_PARALLEL_LOOP_STATIC): Use the
>         renamed attribute list.
>         (BUILT_IN_GOMP_PARALLEL_LOOP_GUIDED): Likewise.
>         (BUILT_IN_GOMP_PARALLEL_LOOP_NONMONOTONIC_DYNAMIC): Likewise.
>         (BUILT_IN_GOMP_PARALLEL_LOOP_NONMONOTONIC_RUNTIME): Likewise.
>         (BUILT_IN_GOMP_PARALLEL): Likewise.
>         (BUILT_IN_GOMP_PARALLEL_SECTIONS): Likewise.
>         (BUILT_IN_GOMP_TEAMS_REG): Likewise.
>         * tree-core.h: Update the ECF_CB flag comment.
>
> gcc/c-family/ChangeLog:
>
>         * c-attribs.cc (handle_callback_only_attribute): Moved from
>         attr-callback.cc.
>         (get_nth_list_elem): Likewise.
>
> gcc/fortran/ChangeLog:
>
>         * f95-lang.cc (ATTR_CALLBACK_GOMP_LIST): Rename to
>         ATTR_CALLBACK_ONLY_GOMP_LIST.
>         (ATTR_CALLBACK_ONLY_GOMP_LIST): Fortran counterpart for the
>         attribute list in builtin-attrs.def.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/attr-callback.c: New test.
>         * gcc.dg/ipa/ipcp-cb2.c: New test.
>

On Linux/x86-64, I got

FAIL: gcc.dg/attr-callback.c  (test for errors, line 52)
FAIL: gcc.dg/attr-callback.c  (test for errors, line 56)
FAIL: gcc.dg/attr-callback.c  (test for errors, line 60)
FAIL: gcc.dg/attr-callback.c (test for excess errors)

-- 
H.J.