From patchwork Wed Jan 10 12:47:49 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 858265 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=sourceware.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=libc-alpha-return-89002-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="gelazyCz"; dkim-atps=neutral Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zGpjQ33hDz9s7n for ; Wed, 10 Jan 2018 23:48:58 +1100 (AEDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:message-id:in-reply-to :references; q=dns; s=default; b=t42zw3VBTDnYAPYZmUMn1JvP3/wAZrf XB6Utji/G5WA0NnyU01KHo85u1L/2KoGNOzndSJvGjwHOtcMYSgzJ97uXEuB7Pcf sxtj1WXu1mkl0vGkWv2O9cMbBdlL2pu8SNre35CmMYxC1i+owoshwPBT+WrVPmh3 fVLZj3qnYO0w= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:message-id:in-reply-to :references; s=default; bh=AFBUbl1c7jIXAK8vnbld8mP1SQ8=; b=gelaz yCzY4wQXZBbLiQHjAApndnSWFseea+56qBMqOMJytkcfYVVX/vlJU5XGsEe25j08 cCAvkkzuG8AZAlcz1QK+VVjBxotBEXivl+DHIf7i6K2pXdpivgKmLdIkBc7X3nKh QsIhTKJCSql6+V1um1ShmWY9dYYGitwCVLr0HY= Received: (qmail 129704 invoked by alias); 10 Jan 2018 12:48:43 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 121182 invoked by uid 89); 10 Jan 2018 12:48:28 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.9 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.2 spammy=H*Ad:U*rth X-HELO: mail-qk0-f195.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=F7n65JWH6DK72UlwEL9kyZ/kWe/DcSZGPSRiCswFaYI=; b=JlDke3d03dgLXQE2J24Rf5jOk+H/46KIwFDVsTG18TUSdCsOwNUXTjDscQZJlAsyTh CWoR66i4wjgjbUXD8fSFPnD2P9e2O1Ab7bfaLRQas8vJAvM/9xFmeinpq00zH8fL+tfS X4nT9VM5kGdj1ViJvYWeCaQFPvb6eI8XV8HFbx+jf86DD0yazt6+E/BiyiOO2R66AucH OAL+M7AdG1tvjDhaQNAGP7beZguglcxI0uGxm7LeUWbwtDGcpoT47vJHZZKLNzJhGOCd TiaagKcBn5LkVuOlHj11A3rFRMxlNM043ZqslMwR59j1LaAOUph2O6bSUpF5qai7bZXz 6LMw== X-Gm-Message-State: AKwxytcSd1GPwmERGibJ/DqpvKYVWps5xbWB6SGnYnPOg9zar2EjK8Tj B5yXONkAQ3QqFUEoK4fg/3RqNftjq0Y= X-Google-Smtp-Source: ACJfBotKQj+7vCkCmjaLNp38LIf4wfJviXU6HIlK9t/kS4P9iVZrJdVKCnaArZ5Fm48BNGHcrBvOvQ== X-Received: by 10.55.119.132 with SMTP id s126mr25932845qkc.250.1515588496936; Wed, 10 Jan 2018 04:48:16 -0800 (PST) From: Adhemerval Zanella To: libc-alpha@sourceware.org Cc: Richard Henderson Subject: [PATCH v3 05/18] string: Improve generic strlen Date: Wed, 10 Jan 2018 10:47:49 -0200 Message-Id: <1515588482-15744-6-git-send-email-adhemerval.zanella@linaro.org> In-Reply-To: <1515588482-15744-1-git-send-email-adhemerval.zanella@linaro.org> References: <1515588482-15744-1-git-send-email-adhemerval.zanella@linaro.org> From: Richard Henderson New algorithm have the following key differences: - Reads first word unaligned and use string-maskoff functions to remove unwanted data. This strategy follow assemble optimized ones for powerpc, sparc, and SH. - Use of has_zero and index_first_zero parametrized functions. Checked on x86_64-linux-gnu, i686-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu by removing the arch-specific assembly implementation and disabling multi-arch (it covers both LE and BE for 64 and 32 bits). [BZ #5806] * string/strlen.c: Use them. --- string/strlen.c | 83 +++++++++++---------------------------------------------- 1 file changed, 15 insertions(+), 68 deletions(-) diff --git a/string/strlen.c b/string/strlen.c index 8ce1318..6bd0ed9 100644 --- a/string/strlen.c +++ b/string/strlen.c @@ -20,6 +20,11 @@ #include #include +#include +#include +#include +#include +#include #undef strlen @@ -32,78 +37,20 @@ size_t STRLEN (const char *str) { - const char *char_ptr; - const unsigned long int *longword_ptr; - unsigned long int longword, himagic, lomagic; + /* Align pointer to sizeof op_t. */ + const uintptr_t s_int = (uintptr_t) str; + const op_t *word_ptr = (const op_t*) (s_int & -sizeof (op_t)); - /* Handle the first few characters by reading one character at a time. - Do this until CHAR_PTR is aligned on a longword boundary. */ - for (char_ptr = str; ((unsigned long int) char_ptr - & (sizeof (longword) - 1)) != 0; - ++char_ptr) - if (*char_ptr == '\0') - return char_ptr - str; + /* Read and MASK the first word. */ + op_t word = *word_ptr | create_mask (s_int); - /* All these elucidatory comments refer to 4-byte longwords, - but the theory applies equally well to 8-byte longwords. */ - - longword_ptr = (unsigned long int *) char_ptr; - - /* Bits 31, 24, 16, and 8 of this number are zero. Call these bits - the "holes." Note that there is a hole just to the left of - each byte, with an extra at the end: - - bits: 01111110 11111110 11111110 11111111 - bytes: AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD - - The 1-bits make sure that carries propagate to the next 0-bit. - The 0-bits provide holes for carries to fall into. */ - himagic = 0x80808080L; - lomagic = 0x01010101L; - if (sizeof (longword) > 4) + while (1) { - /* 64-bit version of the magic. */ - /* Do the shift in two steps to avoid a warning if long has 32 bits. */ - himagic = ((himagic << 16) << 16) | himagic; - lomagic = ((lomagic << 16) << 16) | lomagic; + if (has_zero (word)) + break; + word = *++word_ptr; } - if (sizeof (longword) > 8) - abort (); - /* Instead of the traditional loop which tests each character, - we will test a longword at a time. The tricky part is testing - if *any of the four* bytes in the longword in question are zero. */ - for (;;) - { - longword = *longword_ptr++; - - if (((longword - lomagic) & ~longword & himagic) != 0) - { - /* Which of the bytes was the zero? If none of them were, it was - a misfire; continue the search. */ - - const char *cp = (const char *) (longword_ptr - 1); - - if (cp[0] == 0) - return cp - str; - if (cp[1] == 0) - return cp - str + 1; - if (cp[2] == 0) - return cp - str + 2; - if (cp[3] == 0) - return cp - str + 3; - if (sizeof (longword) > 4) - { - if (cp[4] == 0) - return cp - str + 4; - if (cp[5] == 0) - return cp - str + 5; - if (cp[6] == 0) - return cp - str + 6; - if (cp[7] == 0) - return cp - str + 7; - } - } - } + return ((const char *) word_ptr) + index_first_zero (word) - str; } libc_hidden_builtin_def (strlen)