From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 964853854153 for ; Wed, 16 Aug 2023 16:05:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 964853854153 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692201946; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MhNUsbgwYtIlY23Gh6U4TedvsyhV6B+Y4i+VY4uri1E=; b=Cy9ObGanhbwp4OriqcDQlR40+oGGVwgkPvcsCvWMI5Aq1s+fDogvf4t63PT6G5jmbloXNo eJY+UjtSg81yZPYTJ+Jwt3kdI7MiJObuGSYBRyqWuOWK3i0h/P27WvrTumUmQmzDpQNleH ws5+5x2mMfbAHAwiIoZJhDF+sqvDRu8= Received: from mail-lj1-f198.google.com (mail-lj1-f198.google.com [209.85.208.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-553-cmv88R9mN-KyJQvVhoqG_w-1; Wed, 16 Aug 2023 12:05:43 -0400 X-MC-Unique: cmv88R9mN-KyJQvVhoqG_w-1 Received: by mail-lj1-f198.google.com with SMTP id 38308e7fff4ca-2ba0f27a4c9so65263641fa.1 for ; Wed, 16 Aug 2023 09:05:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692201942; x=1692806742; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MhNUsbgwYtIlY23Gh6U4TedvsyhV6B+Y4i+VY4uri1E=; b=Eftgdi0QTzcHsX6SAD+pqHFv4vsHCwtX1Q0zHsapCHW4+BKLJNaXaiLNzxxbOKgv0w jaiwxOKPlCwW9hQ1YRfBgoCnmnxU67OqStTgbq9L6cjy4psdEc8wMViN7EaIG2f9fUop cLBQ0gpwaHRTX+//91nDDjOa/VzFxmTNaVNbgdcAM4MvU9EuFWa0mqovqIoqch2MkuHA 71qHAkVzz7xcXJUUyfJn3H3FB9P8CRkSEt7jI9ps+/CChahHPtHI2ju/ObgaOr6glt2e 9gs92XUXmK0N3nghwHneI2k36NuldjGUCd01qIBTjUv0zYU9hO+si0+Om/42ucG597vC hBoA== X-Gm-Message-State: AOJu0Yyr1HNeXp4ImyopgXEac7V9nXQcEI5MHEq5+9nmJUKKP64VO0p5 xXvV2iD/CCAxt6eUcffxHmPniogNfEwOJlpz35fg+vSA5uYFpgwby6A652UDg0+61RTdY9VBCF7 yn7s7j2q77O0dWIqxXRd09HBIRZlYqII= X-Received: by 2002:a2e:9b84:0:b0:2b9:48f1:b195 with SMTP id z4-20020a2e9b84000000b002b948f1b195mr1666110lji.44.1692201942023; Wed, 16 Aug 2023 09:05:42 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEpND9YdGjM4+eio7rwyqjB6E66aa0X4z2lFaa7FJqsbgSN2AG2k9zEKNRyz3xMdSMjDI60Vvb/eWflx6G5FB0= X-Received: by 2002:a2e:9b84:0:b0:2b9:48f1:b195 with SMTP id z4-20020a2e9b84000000b002b948f1b195mr1666090lji.44.1692201941639; Wed, 16 Aug 2023 09:05:41 -0700 (PDT) MIME-Version: 1.0 References: <20230414194512.2569383-1-ppalka@redhat.com> In-Reply-To: From: Patrick Palka Date: Wed, 16 Aug 2023 12:05:30 -0400 Message-ID: Subject: Re: [PATCH 1/2] libstdc++: Convert _RangeAdaptorClosure into a CRTP class [PR108827] To: Patrick Palka Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-12.8 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Sun, Apr 16, 2023 at 11:24=E2=80=AFPM Patrick Palka = wrote: > > On Fri, 14 Apr 2023, Patrick Palka wrote: > > > Using the CRTP idiom for this base class avoids bloating the size of a > > pipeline when adding distinct empty range adaptor closure objects to it= , > > as detailed in section 4.1 of P2387R3. > > > > But it means we can no longer define its operator| overloads as hidden > > friends, since each instantiation of _RangeAdaptorClosure would then > > introduce its own logically different hidden friends. So for example > > during overload resolution for the outer pipe operator in > > > > :x | (views::reverse | views::join) > > > > we'd have to consider 6 different hidden operator| friends: > > > > 2 from _RangeAdaptorClosure<_Reverse> > > 2 from _RangeAdaptorClosure<_Join> > > 2 from _RangeAdaptorClosure<_Pipe<_Reverse, _Join>> > > > > which is wasteful and can even cause hard errors in some cases. So we > > instead define the operator| overloads at namespace scope in an isolate= d > > namespace. > > On second thought, since this doesn't fix a bug or add new functionality > it seems more like GCC 14 material. The size reduction is nice but it's > probably not a big deal in practice since adaptor pipelines are usually > very transient objects that don't get passed around as function > arguments etc. Ping, does this look OK for trunk? > > But perhaps the second patch implementing range_adaptor_closure would be > desirable for GCC 13? I'll post an updated standalone version of that > patch for separate consideration. > > > > > PR libstdc++/108827 > > > > libstdc++-v3/ChangeLog: > > > > * include/std/ranges (__adaptor::_RangeAdaptorClosure): Move ... > > (__adaptor::__closure::_RangeAdaptorClosure): ... here and turn > > it into a CRTP class template. Move hidden operator| friends > > into namespace scope and adjust their constraints. Add a > > using-declaration for this at __adaptor::_RangeAdaptorClosure. > > (__closure::__is_range_adaptor_closure_fn): Define. > > (__closure::__is_range_adaptor_closure): Define. > > (__adaptor::_Partial): Adjust use of _RangeAdaptorClosure. > > (__adaptor::_Pipe): Likewise. > > (views::_All): Likewise. > > (views::_Join): Likewise. > > (views::_Common): Likewise. > > (views::_Reverse): Likewise. > > (views::_Elements): Likewise. > > (views::_Adjacent): Likewise. > > (views::_AsRvalue): Likewise. > > (views::_Enumerate): Likewise. > > (views::_AsConst): Likewise. > > * testsuite/std/ranges/adaptors/all.cc: Reintroduce > > static_assert expecting that adding empty range adaptor > > closure objects to a pipeline doesn't increase the size of a > > pipeline. > > --- > > libstdc++-v3/include/std/ranges | 69 +++++++++++-------- > > .../testsuite/std/ranges/adaptors/all.cc | 7 -- > > 2 files changed, 42 insertions(+), 34 deletions(-) > > > > diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std= /ranges > > index 283d757faa4..531ec6f68b3 100644 > > --- a/libstdc++-v3/include/std/ranges > > +++ b/libstdc++-v3/include/std/ranges > > @@ -872,30 +872,45 @@ namespace views::__adaptor > > template > > struct _Pipe; > > > > - // The base class of every range adaptor closure. > > - // > > - // The derived class should define the optional static data member > > - // _S_has_simple_call_op to true if the behavior of this adaptor is > > - // independent of the constness/value category of the adaptor object= . > > - struct _RangeAdaptorClosure > > + namespace __closure > > { > > + // The base class of every range adaptor closure. > > + // > > + // The derived class should define the optional static data member > > + // _S_has_simple_call_op to true if the behavior of this adaptor i= s > > + // independent of the constness/value category of the adaptor obje= ct. > > + template > > + struct _RangeAdaptorClosure > > + { }; > > + > > + template > > + requires (!same_as<_Tp, _RangeAdaptorClosure<_Up>>) > > + void __is_range_adaptor_closure_fn > > + (const _Tp&, const _RangeAdaptorClosure<_Up>&); // not defined > > + > > + template > > + concept __is_range_adaptor_closure > > + =3D requires (_Tp __t) { __closure::__is_range_adaptor_closure_fn= (__t, __t); }; > > + > > // range | adaptor is equivalent to adaptor(range). > > template > > - requires derived_from, _RangeAdaptorClosur= e> > > + requires __is_range_adaptor_closure<_Self> > > && __adaptor_invocable<_Self, _Range> > > - friend constexpr auto > > + constexpr auto > > operator|(_Range&& __r, _Self&& __self) > > { return std::forward<_Self>(__self)(std::forward<_Range>(__r));= } > > > > // Compose the adaptors __lhs and __rhs into a pipeline, returning > > // another range adaptor closure object. > > template > > - requires derived_from<_Lhs, _RangeAdaptorClosure> > > - && derived_from<_Rhs, _RangeAdaptorClosure> > > - friend constexpr auto > > + requires __is_range_adaptor_closure<_Lhs> > > + && __is_range_adaptor_closure<_Rhs> > > + constexpr auto > > operator|(_Lhs __lhs, _Rhs __rhs) > > { return _Pipe<_Lhs, _Rhs>{std::move(__lhs), std::move(__rhs)}; = } > > - }; > > + } // namespace __closure > > + > > + using __closure::_RangeAdaptorClosure; > > > > // The base class of every range adaptor non-closure. > > // > > @@ -937,7 +952,7 @@ namespace views::__adaptor > > // A range adaptor closure that represents partial application of > > // the range adaptor _Adaptor with arguments _Args. > > template > > - struct _Partial : _RangeAdaptorClosure > > + struct _Partial : _RangeAdaptorClosure<_Partial<_Adaptor, _Args...= >> > > { > > tuple<_Args...> _M_args; > > > > @@ -978,7 +993,7 @@ namespace views::__adaptor > > // A lightweight specialization of the above primary template for > > // the common case where _Adaptor accepts a single extra argument. > > template > > - struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure > > + struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure<_Partial<_A= daptor, _Arg>> > > { > > _Arg _M_arg; > > > > @@ -1011,7 +1026,7 @@ namespace views::__adaptor > > template > > requires __adaptor_has_simple_extra_args<_Adaptor, _Args...> > > && (is_trivially_copyable_v<_Args> && ...) > > - struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure > > + struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure<_Partia= l<_Adaptor, _Args...>> > > { > > tuple<_Args...> _M_args; > > > > @@ -1041,7 +1056,7 @@ namespace views::__adaptor > > template > > requires __adaptor_has_simple_extra_args<_Adaptor, _Arg> > > && is_trivially_copyable_v<_Arg> > > - struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure > > + struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure<_Partial<_A= daptor, _Arg>> > > { > > _Arg _M_arg; > > > > @@ -1066,7 +1081,7 @@ namespace views::__adaptor > > // A range adaptor closure that represents composition of the range > > // adaptor closures _Lhs and _Rhs. > > template > > - struct _Pipe : _RangeAdaptorClosure > > + struct _Pipe : _RangeAdaptorClosure<_Pipe<_Lhs, _Rhs>> > > { > > [[no_unique_address]] _Lhs _M_lhs; > > [[no_unique_address]] _Rhs _M_rhs; > > @@ -1102,7 +1117,7 @@ namespace views::__adaptor > > template > > requires __closure_has_simple_call_op<_Lhs> > > && __closure_has_simple_call_op<_Rhs> > > - struct _Pipe<_Lhs, _Rhs> : _RangeAdaptorClosure > > + struct _Pipe<_Lhs, _Rhs> : _RangeAdaptorClosure<_Pipe<_Lhs, _Rhs>> > > { > > [[no_unique_address]] _Lhs _M_lhs; > > [[no_unique_address]] _Rhs _M_rhs; > > @@ -1264,7 +1279,7 @@ namespace views::__adaptor > > concept __can_owning_view =3D requires { owning_view{std::declval= <_Range>()}; }; > > } // namespace __detail > > > > - struct _All : __adaptor::_RangeAdaptorClosure > > + struct _All : __adaptor::_RangeAdaptorClosure<_All> > > { > > template > > static constexpr bool > > @@ -3048,7 +3063,7 @@ namespace views::__adaptor > > =3D requires { join_view>{std::declval<_Range>()}= ; }; > > } // namespace __detail > > > > - struct _Join : __adaptor::_RangeAdaptorClosure > > + struct _Join : __adaptor::_RangeAdaptorClosure<_Join> > > { > > template > > requires __detail::__can_join_view<_Range> > > @@ -3842,7 +3857,7 @@ namespace views::__adaptor > > =3D requires { common_view{std::declval<_Range>()}; }; > > } // namespace __detail > > > > - struct _Common : __adaptor::_RangeAdaptorClosure > > + struct _Common : __adaptor::_RangeAdaptorClosure<_Common> > > { > > template > > requires __detail::__already_common<_Range> > > @@ -3963,7 +3978,7 @@ namespace views::__adaptor > > =3D requires { reverse_view{std::declval<_Range>()}; }; > > } // namespace __detail > > > > - struct _Reverse : __adaptor::_RangeAdaptorClosure > > + struct _Reverse : __adaptor::_RangeAdaptorClosure<_Reverse> > > { > > template > > requires __detail::__is_reverse_view> > > @@ -4363,7 +4378,7 @@ namespace views::__adaptor > > } // namespace __detail > > > > template > > - struct _Elements : __adaptor::_RangeAdaptorClosure > > + struct _Elements : __adaptor::_RangeAdaptorClosure<_Elements<_Nm= >> > > { > > template > > requires __detail::__can_elements_view<_Nm, _Range> > > @@ -5484,7 +5499,7 @@ namespace views::__adaptor > > } > > > > template > > - struct _Adjacent : __adaptor::_RangeAdaptorClosure > > + struct _Adjacent : __adaptor::_RangeAdaptorClosure<_Adjacent<_Nm= >> > > { > > template > > requires (_Nm =3D=3D 0) || __detail::__can_adjacent_view<_Nm, _= Range> > > @@ -8609,7 +8624,7 @@ namespace views::__adaptor > > concept __can_as_rvalue_view =3D requires { as_rvalue_view(std::d= eclval<_Tp>()); }; > > } > > > > - struct _AsRvalue : __adaptor::_RangeAdaptorClosure > > + struct _AsRvalue : __adaptor::_RangeAdaptorClosure<_AsRvalue> > > { > > template > > requires __detail::__can_as_rvalue_view<_Range> > > @@ -8918,7 +8933,7 @@ namespace views::__adaptor > > =3D requires { enumerate_view>(std::declval<_Tp>());= }; > > } > > > > - struct _Enumerate : __adaptor::_RangeAdaptorClosure > > + struct _Enumerate : __adaptor::_RangeAdaptorClosure<_Enumerate> > > { > > template > > requires __detail::__can_enumerate_view<_Range> > > @@ -9004,7 +9019,7 @@ namespace views::__adaptor > > concept __can_as_const_view =3D requires { as_const_view(std::dec= lval<_Range>()); }; > > } > > > > - struct _AsConst : __adaptor::_RangeAdaptorClosure > > + struct _AsConst : __adaptor::_RangeAdaptorClosure<_AsConst> > > { > > template > > constexpr auto > > diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc b/libstd= c++-v3/testsuite/std/ranges/adaptors/all.cc > > index 57cb542174b..6bbaf73a20a 100644 > > --- a/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc > > +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc > > @@ -105,12 +105,6 @@ static_assert(std::is_empty_v > | views::common > > | views::keys > > | views::reverse)>); > > -#if 0 > > -// Adding empty range adaptor closure objects to a pipeline used to no= t > > -// increase the size of the pipeline, but now that our range adaptor c= losure > > -// objects derive from a common empty base class, [[no_unique_address]= ] can no > > -// longer make two empty adjacent range adaptor closure objects occupy= the same > > -// data member address. > > static_assert(sizeof(decltype(views::take(5) | views::drop(5))) > > =3D=3D sizeof(decltype(views::take(5) > > | views::join > > @@ -119,7 +113,6 @@ static_assert(sizeof(decltype(views::take(5) | view= s::drop(5))) > > | views::keys > > | views::drop(5) > > | views::reverse))); > > -#endif > > > > template > > void > > -- > > 2.40.0.335.g9857273be0 > > > >