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Mon, 11 Jan 2021 04:35:29 -0800 (PST) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id i4sm4733065qtw.35.2021.01.11.04.35.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Jan 2021 04:35:28 -0800 (PST) Subject: Re: [PATCH 1/3] posix: Remove alloca usage on regex set_regs To: Paul Eggert Cc: libc-alpha@sourceware.org, bug-gnulib@gnu.org References: <20210106181707.1738066-1-adhemerval.zanella@linaro.org> From: Adhemerval Zanella Autocrypt: addr=adhemerval.zanella@linaro.org; prefer-encrypt=mutual; keydata= mQINBFcVGkoBEADiQU2x/cBBmAVf5C2d1xgz6zCnlCefbqaflUBw4hB/bEME40QsrVzWZ5Nq 8kxkEczZzAOKkkvv4pRVLlLn/zDtFXhlcvQRJ3yFMGqzBjofucOrmdYkOGo0uCaoJKPT186L NWp53SACXguFJpnw4ODI64ziInzXQs/rUJqrFoVIlrPDmNv/LUv1OVPKz20ETjgfpg8MNwG6 iMizMefCl+RbtXbIEZ3TE/IaDT/jcOirjv96lBKrc/pAL0h/O71Kwbbp43fimW80GhjiaN2y WGByepnkAVP7FyNarhdDpJhoDmUk9yfwNuIuESaCQtfd3vgKKuo6grcKZ8bHy7IXX1XJj2X/ BgRVhVgMHAnDPFIkXtP+SiarkUaLjGzCz7XkUn4XAGDskBNfbizFqYUQCaL2FdbW3DeZqNIa nSzKAZK7Dm9+0VVSRZXP89w71Y7JUV56xL/PlOE+YKKFdEw+gQjQi0e+DZILAtFjJLoCrkEX w4LluMhYX/X8XP6/C3xW0yOZhvHYyn72sV4yJ1uyc/qz3OY32CRy+bwPzAMAkhdwcORA3JPb kPTlimhQqVgvca8m+MQ/JFZ6D+K7QPyvEv7bQ7M+IzFmTkOCwCJ3xqOD6GjX3aphk8Sr0dq3 4Awlf5xFDAG8dn8Uuutb7naGBd/fEv6t8dfkNyzj6yvc4jpVxwARAQABtElBZGhlbWVydmFs IFphbmVsbGEgTmV0dG8gKExpbmFybyBWUE4gS2V5KSA8YWRoZW1lcnZhbC56YW5lbGxhQGxp bmFyby5vcmc+iQI3BBMBCAAhBQJXFRpKAhsDBQsJCAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJ EKqx7BSnlIjv0e8P/1YOYoNkvJ+AJcNUaM5a2SA9oAKjSJ/M/EN4Id5Ow41ZJS4lUA0apSXW NjQg3VeVc2RiHab2LIB4MxdJhaWTuzfLkYnBeoy4u6njYcaoSwf3g9dSsvsl3mhtuzm6aXFH /Qsauav77enJh99tI4T+58rp0EuLhDsQbnBic/ukYNv7sQV8dy9KxA54yLnYUFqH6pfH8Lly sTVAMyi5Fg5O5/hVV+Z0Kpr+ZocC1YFJkTsNLAW5EIYSP9ftniqaVsim7MNmodv/zqK0IyDB GLLH1kjhvb5+6ySGlWbMTomt/or/uvMgulz0bRS+LUyOmlfXDdT+t38VPKBBVwFMarNuREU2 69M3a3jdTfScboDd2ck1u7l+QbaGoHZQ8ZNUrzgObltjohiIsazqkgYDQzXIMrD9H19E+8fw kCNUlXxjEgH/Kg8DlpoYJXSJCX0fjMWfXywL6ZXc2xyG/hbl5hvsLNmqDpLpc1CfKcA0BkK+ k8R57fr91mTCppSwwKJYO9T+8J+o4ho/CJnK/jBy1pWKMYJPvvrpdBCWq3MfzVpXYdahRKHI ypk8m4QlRlbOXWJ3TDd/SKNfSSrWgwRSg7XCjSlR7PNzNFXTULLB34sZhjrN6Q8NQZsZnMNs TX8nlGOVrKolnQPjKCLwCyu8PhllU8OwbSMKskcD1PSkG6h3r0AquQINBFcVGkoBEACgAdbR Ck+fsfOVwT8zowMiL3l9a2DP3Eeak23ifdZG+8Avb/SImpv0UMSbRfnw/N81IWwlbjkjbGTu oT37iZHLRwYUFmA8fZX0wNDNKQUUTjN6XalJmvhdz9l71H3WnE0wneEM5ahu5V1L1utUWTyh VUwzX1lwJeV3vyrNgI1kYOaeuNVvq7npNR6t6XxEpqPsNc6O77I12XELic2+36YibyqlTJIQ V1SZEbIy26AbC2zH9WqaKyGyQnr/IPbTJ2Lv0dM3RaXoVf+CeK7gB2B+w1hZummD21c1Laua +VIMPCUQ+EM8W9EtX+0iJXxI+wsztLT6vltQcm+5Q7tY+HFUucizJkAOAz98YFucwKefbkTp eKvCfCwiM1bGatZEFFKIlvJ2QNMQNiUrqJBlW9nZp/k7pbG3oStOjvawD9ZbP9e0fnlWJIsj 6c7pX354Yi7kxIk/6gREidHLLqEb/otuwt1aoMPg97iUgDV5mlNef77lWE8vxmlY0FBWIXuZ yv0XYxf1WF6dRizwFFbxvUZzIJp3spAao7jLsQj1DbD2s5+S1BW09A0mI/1DjB6EhNN+4bDB SJCOv/ReK3tFJXuj/HbyDrOdoMt8aIFbe7YFLEExHpSk+HgN05Lg5TyTro8oW7TSMTk+8a5M kzaH4UGXTTBDP/g5cfL3RFPl79ubXwARAQABiQIfBBgBCAAJBQJXFRpKAhsMAAoJEKqx7BSn lIjvI/8P/jg0jl4Tbvg3B5kT6PxJOXHYu9OoyaHLcay6Cd+ZrOd1VQQCbOcgLFbf4Yr+rE9l mYsY67AUgq2QKmVVbn9pjvGsEaz8UmfDnz5epUhDxC6yRRvY4hreMXZhPZ1pbMa6A0a/WOSt AgFj5V6Z4dXGTM/lNManr0HjXxbUYv2WfbNt3/07Db9T+GZkpUotC6iknsTA4rJi6u2ls0W9 1UIvW4o01vb4nZRCj4rni0g6eWoQCGoVDk/xFfy7ZliR5B+3Z3EWRJcQskip/QAHjbLa3pml xAZ484fVxgeESOoaeC9TiBIp0NfH8akWOI0HpBCiBD5xaCTvR7ujUWMvhsX2n881r/hNlR9g fcE6q00qHSPAEgGr1bnFv74/1vbKtjeXLCcRKk3Ulw0bY1OoDxWQr86T2fZGJ/HIZuVVBf3+ gaYJF92GXFynHnea14nFFuFgOni0Mi1zDxYH/8yGGBXvo14KWd8JOW0NJPaCDFJkdS5hu0VY 7vJwKcyHJGxsCLU+Et0mryX8qZwqibJIzu7kUJQdQDljbRPDFd/xmGUFCQiQAncSilYOcxNU EMVCXPAQTteqkvA+gNqSaK1NM9tY0eQ4iJpo+aoX8HAcn4sZzt2pfUB9vQMTBJ2d4+m/qO6+ cFTAceXmIoFsN8+gFN3i8Is3u12u8xGudcBPvpoy4OoG Message-ID: <3c95294d-ab4f-3a6a-9979-88d98b4ef1be@linaro.org> Date: Mon, 11 Jan 2021 09:35:26 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-6.3 required=5.0 tests=BAYES_00, BODY_8BITS, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Jan 2021 12:35:31 -0000 On 08/01/2021 17:14, Paul Eggert wrote: > On 1/6/21 10:17 AM, Adhemerval Zanella wrote: >> It replaces the regmatch_t with a dynarray list. > > regexec.c is shared with Gnulib, so some work needed to be done on the Gnulib side for this patch since Gnulib didn't have dynarray. Dynarray is something I've been meaning to add to Gnulib for some time, so I did that by installing the first attached patch into Gnulib. Could you please propagate the new Gnulib dynarray sources into glibc so that they stay in sync? As near as I can make out, the glibc dynarray files can now be identical to the new Gnulib files; if not, please let me know. I will check and sync the differences. > > >>   posix/regexec.c | 62 ++++++++++++++++++++++++------------------------- >>   1 file changed, 31 insertions(+), 31 deletions(-) >> ... >> @@ -1355,6 +1352,16 @@ pop_fail_stack (struct re_fail_stack_t *fs, Idx *pidx, Idx nregs, >>     return fs->stack[num].node; >>   } >>   + >> +#define DYNARRAY_STRUCT  regmatch_list >> +#define DYNARRAY_ELEMENT regmatch_t >> +#define DYNARRAY_PREFIX  regmatch_list_ >> +#include >> + >> +static void update_regs (const re_dfa_t *dfa, regmatch_t *pmatch, >> +             struct regmatch_list *prev_idx_match, Idx cur_node, >> +             Idx cur_idx, Idx nmatch); >> + >>   /* Set the positions where the subexpressions are starts/ends to registers >>      PMATCH. >>      Note: We assume that pmatch[0] is already set, and >> @@ -1370,8 +1377,8 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch, >>     re_node_set eps_via_nodes; >>     struct re_fail_stack_t *fs; >>     struct re_fail_stack_t fs_body = { 0, 2, NULL }; >> -  regmatch_t *prev_idx_match; >> -  bool prev_idx_match_malloced = false; >> +  struct regmatch_list prev_idx_match; >> +  regmatch_list_init (&prev_idx_match); >>       DEBUG_ASSERT (nmatch > 1); >>     DEBUG_ASSERT (mctx->state_log != NULL); >> @@ -1388,23 +1395,18 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch, >>     cur_node = dfa->init_node; >>     re_node_set_init_empty (&eps_via_nodes); >>   -  if (__libc_use_alloca (nmatch * sizeof (regmatch_t))) >> -    prev_idx_match = (regmatch_t *) alloca (nmatch * sizeof (regmatch_t)); >> -  else >> +  if (!regmatch_list_resize (&prev_idx_match, nmatch)) >>       { >> -      prev_idx_match = re_malloc (regmatch_t, nmatch); >> -      if (prev_idx_match == NULL) >> -    { >> -      free_fail_stack_return (fs); >> -      return REG_ESPACE; >> -    } >> -      prev_idx_match_malloced = true; >> +      regmatch_list_free (&prev_idx_match); >> +      free_fail_stack_return (fs); >> +      return REG_ESPACE; >>       } > > These three hunks are good, but you can omit most of the other hunks (and improve performance a bit) by inserting the following line after the 3rd hunk: > > +  regmatch_t *prev_idx_match = regmatch_list_begin (&prev_match); > > since the dynarray doesn't grow after that and this means you don't need to change the rest of the code to use prev_match rather than prev_idx_match. The only other hunks you need to retain are the ones replacing re_free with regmastch_list_free. > > I've made this improvement to Gnulib by installing the second attached patch, so you should be able to copy Gnulib regexec.c to glibc without changing it. Ok, I will check and sync with gnulib.