[PATCH v24 33/33] libstdc++: Optimize std::is_invocable compilation performance

[Ken Matsui]

On Mon, Oct 23, 2023 at 10:05 AM Patrick Palka <ppalka@redhat.com> wrote:

> On Fri, Oct 20, 2023 at 12:22 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
> >
> > This patch optimizes the compilation performance of std::is_invocable
> > by dispatching to the new __is_invocable built-in trait.
> >
> > libstdc++-v3/ChangeLog:
> >
> >         * include/std/type_traits (is_invocable): Use __is_invocable
> >         built-in trait.
>
> Nice!  We should use the trait directly in is_invocable_v too.
>

Thank you! But we want to take account of static_assert’s in is_invocable,
so I think we cannot use the built-in directly?


> >         * testsuite/20_util/is_invocable/incomplete_args_neg.cc: Handle
> >         the new error from __is_invocable.
> >         * testsuite/20_util/is_invocable/incomplete_neg.cc: Likewise.
> >
> > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > ---
> >  libstdc++-v3/include/std/type_traits                        | 6 ++++++
> >  .../testsuite/20_util/is_invocable/incomplete_args_neg.cc   | 1 +
> >  .../testsuite/20_util/is_invocable/incomplete_neg.cc        | 1 +
> >  3 files changed, 8 insertions(+)
> >
> > diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> > index 75a94cb8d7e..91851b78c7e 100644
> > --- a/libstdc++-v3/include/std/type_traits
> > +++ b/libstdc++-v3/include/std/type_traits
> > @@ -3167,9 +3167,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> >      using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
> >
> >    /// std::is_invocable
> > +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_invocable)
> > +  template<typename _Fn, typename... _ArgTypes>
> > +    struct is_invocable
> > +    : public __bool_constant<__is_invocable(_Fn, _ArgTypes...)>
> > +#else
> >    template<typename _Fn, typename... _ArgTypes>
> >      struct is_invocable
> >      : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>,
> void>::type
> > +#endif
> >      {
> >
> static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
> >         "_Fn must be a complete class or an unbounded array");
> > diff --git
> a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> > index 34d1d9431d1..3f9e5274f3c 100644
> > --- a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> > +++ b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> > @@ -18,6 +18,7 @@
> >  // <http://www.gnu.org/licenses/>.
> >
> >  // { dg-error "must be a complete class" "" { target *-*-* } 0 }
> > +// { dg-prune-output "invalid use of incomplete type" }
> >
> >  #include <type_traits>
> >
> > diff --git
> a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> > index e1e54d25ee5..92af48c48b6 100644
> > --- a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> > +++ b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> > @@ -18,6 +18,7 @@
> >  // <http://www.gnu.org/licenses/>.
> >
> >  // { dg-error "must be a complete class" "" { target *-*-* } 0 }
> > +// { dg-prune-output "invalid use of incomplete type" }
> >
> >  #include <type_traits>
> >
> > --
> > 2.42.0
> >
>
>
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