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[69.118.112.187]) by smtp.gmail.com with ESMTPSA id l2-20020a0cac02000000b00655e428604esm3463332qvb.137.2023.09.18.05.58.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Sep 2023 05:58:45 -0700 (PDT) From: Patrick Palka X-Google-Original-From: Patrick Palka Date: Mon, 18 Sep 2023 08:58:44 -0400 (EDT) To: Jason Merrill cc: Patrick Palka , gcc-patches@gcc.gnu.org Subject: Re: [PATCH] c++: optimize tsubst_template_decl for function templates In-Reply-To: <8bece04e-88ef-0a83-8cc0-5f9546b085a0@redhat.com> Message-ID: <91648025-410e-eb5e-a7c5-a230ebea73cd@idea> References: <20230917191304.1483576-1-ppalka@redhat.com> <8bece04e-88ef-0a83-8cc0-5f9546b085a0@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-13.8 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, 17 Sep 2023, Jason Merrill wrote: > On 9/17/23 15:13, Patrick Palka wrote: > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > > trunk? > > > > -- >8 -- > > > > r14-2655-g92d1425ca78040 made instantiate_template avoid redundantly > > performing a specialization lookup when instantiating a function or > > alias template. This patch applies the same optimization to > > tsubst_template_decl when (partially) instantiating a function template, > > which allows us to remove a check from register_specialization since > > tsubst_function_decl no longer calls register_specialization for > > a function template partial instantiation. > > > > gcc/cp/ChangeLog: > > > > * pt.cc (register_specialization): Remove now-unnecessary > > early exit for FUNCTION_DECL partial instantiation. > > (tsubst_template_decl): Pass use_spec_table=false to > > tsubst_function_decl. Set DECL_TI_ARGS of a non-lambda > > FUNCTION_DECL specialization to the full set of arguments. > > Simplify register_specialization call accordingly. > > > > gcc/testsuite/ChangeLog: > > > > * g++.dg/template/nontype12.C: Expect two instead of three > > duplicate diagnostics for A::bar() specialization. > > --- > > gcc/cp/pt.cc | 29 +++++++---------------- > > gcc/testsuite/g++.dg/template/nontype12.C | 1 - > > 2 files changed, 9 insertions(+), 21 deletions(-) > > > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > > index c311a6b88f5..a0296a1ea16 100644 > > --- a/gcc/cp/pt.cc > > +++ b/gcc/cp/pt.cc > > @@ -1507,21 +1507,6 @@ register_specialization (tree spec, tree tmpl, tree > > args, bool is_friend, > > || (TREE_CODE (tmpl) == FIELD_DECL > > && TREE_CODE (spec) == NONTYPE_ARGUMENT_PACK)); > > - if (TREE_CODE (spec) == FUNCTION_DECL > > - && uses_template_parms (DECL_TI_ARGS (spec))) > > - /* This is the FUNCTION_DECL for a partial instantiation. Don't > > - register it; we want the corresponding TEMPLATE_DECL instead. > > - We use `uses_template_parms (DECL_TI_ARGS (spec))' rather than > > - the more obvious `uses_template_parms (spec)' to avoid problems > > - with default function arguments. In particular, given > > - something like this: > > - > > - template void f(T t1, T t = T()) > > - > > - the default argument expression is not substituted for in an > > - instantiation unless and until it is actually needed. */ > > - return spec; > > - > > spec_entry elt; > > elt.tmpl = tmpl; > > elt.args = args; > > @@ -14663,7 +14648,7 @@ tsubst_template_decl (tree t, tree args, > > tsubst_flags_t complain, > > tree in_decl = t; > > tree spec; > > tree tmpl_args; > > - tree full_args; > > + tree full_args = NULL_TREE; > > tree r; > > hashval_t hash = 0; > > @@ -14754,7 +14739,8 @@ tsubst_template_decl (tree t, tree args, > > tsubst_flags_t complain, > > tree inner = decl; > > ++processing_template_decl; > > if (TREE_CODE (inner) == FUNCTION_DECL) > > - inner = tsubst_function_decl (inner, args, complain, lambda_fntype); > > + inner = tsubst_function_decl (inner, args, complain, lambda_fntype, > > + /*use_spec_table=*/false); > > else > > { > > if (TREE_CODE (inner) == TYPE_DECL && !TYPE_DECL_ALIAS_P (inner)) > > @@ -14792,6 +14778,11 @@ tsubst_template_decl (tree t, tree args, > > tsubst_flags_t complain, > > } > > else > > { > > + if (TREE_CODE (inner) == FUNCTION_DECL) > > + /* Set DECL_TI_ARGS to the full set of template arguments, which > > + tsubst_function_decl didn't do due to use_spec_table=false. */ > > + DECL_TI_ARGS (inner) = full_args; > > + > > DECL_TI_TEMPLATE (inner) = r; > > DECL_TI_ARGS (r) = DECL_TI_ARGS (inner); > > } > > @@ -14822,9 +14813,7 @@ tsubst_template_decl (tree t, tree args, > > tsubst_flags_t complain, > > if (TREE_CODE (decl) == FUNCTION_DECL && !lambda_fntype) > > /* Record this non-type partial instantiation. */ > > - register_specialization (r, t, > > - DECL_TI_ARGS (DECL_TEMPLATE_RESULT (r)), > > - false, hash); > > + register_specialization (r, t, full_args, false, hash); > > return r; > > } > > diff --git a/gcc/testsuite/g++.dg/template/nontype12.C > > b/gcc/testsuite/g++.dg/template/nontype12.C > > index 9a9c3ac1e66..e36a9f16f94 100644 > > --- a/gcc/testsuite/g++.dg/template/nontype12.C > > +++ b/gcc/testsuite/g++.dg/template/nontype12.C > > @@ -5,7 +5,6 @@ template struct A > > { > > template int foo(); // { dg-error "double" "" > > { target c++17_down } } > > template class> int bar(); // { dg-bogus > > {double[^\n]*\n[^\n]*C:7:[^\n]*double} "" { xfail c++17_down } } > > - // { dg-error "double" "" { target c++17_down } .-1 } > > Hmm, I thought this line was to check that we get one error even if we don't > want two? The xfailed dg-bogus directive seems to "consume" the two errors, and prevents the dg-error from matching either of them. Before this patch, we issued three duplicate errors and so this arrangement worked out since the xfailed dg-bogus consumes only two of the errors. I'm not sure how to express that we're currently seeing two errors but only want one using _both_ dg-error and dg-bogus.. > > Jason >