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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id d15sm3791960qtd.70.2021.11.09.21.16.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Nov 2021 21:16:25 -0800 (PST) Message-ID: Date: Wed, 10 Nov 2021 00:16:24 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH] c++: use auto_vec in cp_parser_template_argument_list To: Patrick Palka Cc: gcc-patches@gcc.gnu.org References: <20211109160222.3758174-1-ppalka@redhat.com> <5d4d91cf-7e0-921e-2345-734f671372e3@idea> From: Jason Merrill In-Reply-To: <5d4d91cf-7e0-921e-2345-734f671372e3@idea> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-14.0 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Nov 2021 05:16:31 -0000 On 11/9/21 13:42, Patrick Palka wrote: > On Tue, 9 Nov 2021, Jason Merrill wrote: > >> On 11/9/21 11:02, Patrick Palka wrote: >>> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? >> >> OK, though I wonder about using releasing_vec instead of auto_vec; reusing a >> previously allocated vec vs. building one on the stack. > > Thanks a lot. And hmm, I think using reusing a previously allocated vec > here would be tricky since cp_parser_template_argument_list can be > called recursively, and so only the outermost call would be able to > benefit from reuse unless we perhaps maintain a freelist of such vecs > IIUC. We do maintain such a freelist, in make_tree_vector/release_tree_vector, which releasing_vec is a wrapper class for. > Seems like that would complicate the code enough to not be worth > it. > >>> gcc/cp/ChangeLog: >>> >>> * parser.c (cp_parser_template_argument_list): Use auto_vec >>> instead of manual memory management. >>> --- >>> gcc/cp/parser.c | 35 ++++++++--------------------------- >>> 1 file changed, 8 insertions(+), 27 deletions(-) >>> >>> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c >>> index 32de97b08bd..8823399529e 100644 >>> --- a/gcc/cp/parser.c >>> +++ b/gcc/cp/parser.c >>> @@ -18558,11 +18558,6 @@ cp_parser_template_name (cp_parser* parser, >>> static tree >>> cp_parser_template_argument_list (cp_parser* parser) >>> { >>> - tree fixed_args[10]; >>> - unsigned n_args = 0; >>> - unsigned alloced = 10; >>> - tree *arg_ary = fixed_args; >>> - tree vec; >>> bool saved_in_template_argument_list_p; >>> bool saved_ice_p; >>> bool saved_non_ice_p; >>> @@ -18581,16 +18576,15 @@ cp_parser_template_argument_list (cp_parser* >>> parser) >>> parser->non_integral_constant_expression_p = false; >>> /* Parse the arguments. */ >>> + auto_vec args; >>> do >>> { >>> - tree argument; >>> - >>> - if (n_args) >>> + if (!args.is_empty ()) >>> /* Consume the comma. */ >>> cp_lexer_consume_token (parser->lexer); >>> /* Parse the template-argument. */ >>> - argument = cp_parser_template_argument (parser); >>> + tree argument = cp_parser_template_argument (parser); >>> /* If the next token is an ellipsis, we're expanding a template >>> argument pack. */ >>> @@ -18610,29 +18604,16 @@ cp_parser_template_argument_list (cp_parser* >>> parser) >>> argument = make_pack_expansion (argument); >>> } >>> - if (n_args == alloced) >>> - { >>> - alloced *= 2; >>> - >>> - if (arg_ary == fixed_args) >>> - { >>> - arg_ary = XNEWVEC (tree, alloced); >>> - memcpy (arg_ary, fixed_args, sizeof (tree) * n_args); >>> - } >>> - else >>> - arg_ary = XRESIZEVEC (tree, arg_ary, alloced); >>> - } >>> - arg_ary[n_args++] = argument; >>> + args.safe_push (argument); >>> } >>> while (cp_lexer_next_token_is (parser->lexer, CPP_COMMA)); >>> - vec = make_tree_vec (n_args); >>> + int n_args = args.length (); >>> + tree vec = make_tree_vec (n_args); >>> - while (n_args--) >>> - TREE_VEC_ELT (vec, n_args) = arg_ary[n_args]; >>> + for (int i = 0; i < n_args; i++) >>> + TREE_VEC_ELT (vec, i) = args[i]; >>> - if (arg_ary != fixed_args) >>> - free (arg_ary); >>> parser->non_integral_constant_expression_p = saved_non_ice_p; >>> parser->integral_constant_expression_p = saved_ice_p; >>> parser->in_template_argument_list_p = saved_in_template_argument_list_p; >>> >> >> >