From patchwork Wed Feb 1 17:03:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 64097 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 5A503385AC39 for ; Wed, 1 Feb 2023 17:06:22 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5A503385AC39 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1675271182; bh=2SEyxvOct6zIJZeVHDT2AF+/dzL/v9yC+T5860BjCpA=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=EjUGsB4dcdMS6v0aIPHIc9cylHmLwYW+XbNZckIdQD2SPnNSyQXyQ4b63Qj6eV02C kVl1Cub0bpCgxg0HbjxaSjezDt+ArqCqy8MW2pXiAQPE3SEFnGPvCI2d4mOJiY5q1N 09gxPEqUcILMWIr4yy2mM29KMgYv/+0xPDYUJDXk= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-ot1-x329.google.com (mail-ot1-x329.google.com [IPv6:2607:f8b0:4864:20::329]) by sourceware.org (Postfix) with ESMTPS id E4F623858D39 for ; Wed, 1 Feb 2023 17:04:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org E4F623858D39 Received: by mail-ot1-x329.google.com with SMTP id g21-20020a9d6495000000b0068bb336141dso4742638otl.11 for ; Wed, 01 Feb 2023 09:04:27 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=2SEyxvOct6zIJZeVHDT2AF+/dzL/v9yC+T5860BjCpA=; b=V3swTFqAUuA4p5KWDrV6+6tEVS/opT45hQ3LEMQak230Kmzj+cVbo8bwiULBd/WD9e wMtO5/7tWoxYAOFrPWe7L0CCu34mucLtjtErKT+w4lIasog2gRvqOzi70OI+FKWhM68C Hlmk37SSzhw7jekUBryn6oF+7UXG+nS1Neu4+8ZThpOma7LMHCdXTYepUjCCyeNCuHFE WWcAywkHhLEwjgjk+j8JSgudj1PAdp2g0jnK0AYZs4llER1PFBB6+f7u/oW289B/28Wk BoGdg3uptEHqaZXJ7w4yB+o5cPSuGbLlFTOCNocNoqjaTYHFjB0Ck9mBvg9MCLObFM4/ Bjbw== X-Gm-Message-State: AO0yUKXVoq+K2ukOtynRfK/vRlAUxGEldvTWbesve1pEc+pOqevVYCmQ S3IDK6/RIjp91r/vpSPktKTo2FJzUFRRwyUB8L8= X-Google-Smtp-Source: AK7set8Jx3Q4MtKVrtnNGtMNJivVqPhZ+egGncMYDR6Mu2UWvpx9Pwx684XO81MkJzeckpDr8M3eCA== X-Received: by 2002:a9d:4783:0:b0:68b:e2cd:9362 with SMTP id b3-20020a9d4783000000b0068be2cd9362mr1331633otf.33.1675271066323; Wed, 01 Feb 2023 09:04:26 -0800 (PST) Received: from mandiga.. ([2804:1b3:a7c2:1887:d2ed:98c2:d2cc:bf06]) by smtp.gmail.com with ESMTPSA id b17-20020a056830311100b006863ccbf067sm8077090ots.74.2023.02.01.09.04.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Feb 2023 09:04:25 -0800 (PST) To: libc-alpha@sourceware.org, Richard Henderson , Noah Goldstein , Jeff Law , Xi Ruoyao Subject: [PATCH v11 05/29] string: Improve generic strnlen with memchr Date: Wed, 1 Feb 2023 14:03:42 -0300 Message-Id: <20230201170406.303978-6-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230201170406.303978-1-adhemerval.zanella@linaro.org> References: <20230201170406.303978-1-adhemerval.zanella@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-12.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, 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 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-Patchwork-Original-From: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Netto Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" It also cleanups the multiple inclusion by leaving the ifunc implementation to undef the weak_alias and libc_hidden_def. Co-authored-by: Richard Henderson --- string/strnlen.c | 137 +----------------- sysdeps/i386/i686/multiarch/strnlen-c.c | 14 +- .../power4/multiarch/strnlen-ppc32.c | 14 +- sysdeps/s390/strnlen-c.c | 14 +- 4 files changed, 27 insertions(+), 152 deletions(-) diff --git a/string/strnlen.c b/string/strnlen.c index 6ff294eab1..dc23354ec8 100644 --- a/string/strnlen.c +++ b/string/strnlen.c @@ -1,10 +1,6 @@ /* Find the length of STRING, but scan at most MAXLEN characters. Copyright (C) 1991-2023 Free Software Foundation, Inc. - Based on strlen written by Torbjorn Granlund (tege@sics.se), - with help from Dan Sahlin (dan@sics.se); - commentary by Jim Blandy (jimb@ai.mit.edu). - The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the @@ -20,7 +16,6 @@ not, see . */ #include -#include /* Find the length of S, but scan at most MAXLEN characters. If no '\0' terminator is found in that many characters, return MAXLEN. */ @@ -32,134 +27,12 @@ size_t __strnlen (const char *str, size_t maxlen) { - const char *char_ptr, *end_ptr = str + maxlen; - const unsigned long int *longword_ptr; - unsigned long int longword, himagic, lomagic; - - if (maxlen == 0) - return 0; - - if (__glibc_unlikely (end_ptr < str)) - end_ptr = (const char *) ~0UL; - - /* 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') - { - if (char_ptr > end_ptr) - char_ptr = end_ptr; - return char_ptr - str; - } - - /* 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) - { - /* 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 (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. */ - while (longword_ptr < (unsigned long int *) end_ptr) - { - /* We tentatively exit the loop if adding MAGIC_BITS to - LONGWORD fails to change any of the hole bits of LONGWORD. - - 1) Is this safe? Will it catch all the zero bytes? - Suppose there is a byte with all zeros. Any carry bits - propagating from its left will fall into the hole at its - least significant bit and stop. Since there will be no - carry from its most significant bit, the LSB of the - byte to the left will be unchanged, and the zero will be - detected. - - 2) Is this worthwhile? Will it ignore everything except - zero bytes? Suppose every byte of LONGWORD has a bit set - somewhere. There will be a carry into bit 8. If bit 8 - is set, this will carry into bit 16. If bit 8 is clear, - one of bits 9-15 must be set, so there will be a carry - into bit 16. Similarly, there will be a carry into bit - 24. If one of bits 24-30 is set, there will be a carry - into bit 31, so all of the hole bits will be changed. - - The one misfire occurs when bits 24-30 are clear and bit - 31 is set; in this case, the hole at bit 31 is not - changed. If we had access to the processor carry flag, - we could close this loophole by putting the fourth hole - at bit 32! - - So it ignores everything except 128's, when they're aligned - properly. */ - - longword = *longword_ptr++; - - if ((longword - lomagic) & himagic) - { - /* 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); - - char_ptr = cp; - if (cp[0] == 0) - break; - char_ptr = cp + 1; - if (cp[1] == 0) - break; - char_ptr = cp + 2; - if (cp[2] == 0) - break; - char_ptr = cp + 3; - if (cp[3] == 0) - break; - if (sizeof (longword) > 4) - { - char_ptr = cp + 4; - if (cp[4] == 0) - break; - char_ptr = cp + 5; - if (cp[5] == 0) - break; - char_ptr = cp + 6; - if (cp[6] == 0) - break; - char_ptr = cp + 7; - if (cp[7] == 0) - break; - } - } - char_ptr = end_ptr; - } - - if (char_ptr > end_ptr) - char_ptr = end_ptr; - return char_ptr - str; + const char *found = memchr (str, '\0', maxlen); + return found ? found - str : maxlen; } + #ifndef STRNLEN -libc_hidden_def (__strnlen) weak_alias (__strnlen, strnlen) -#endif +libc_hidden_def (__strnlen) libc_hidden_def (strnlen) +#endif diff --git a/sysdeps/i386/i686/multiarch/strnlen-c.c b/sysdeps/i386/i686/multiarch/strnlen-c.c index 351e939a93..beb0350d53 100644 --- a/sysdeps/i386/i686/multiarch/strnlen-c.c +++ b/sysdeps/i386/i686/multiarch/strnlen-c.c @@ -1,10 +1,10 @@ #define STRNLEN __strnlen_ia32 +#include + #ifdef SHARED -# undef libc_hidden_def -# define libc_hidden_def(name) \ - __hidden_ver1 (__strnlen_ia32, __GI_strnlen, __strnlen_ia32); \ - strong_alias (__strnlen_ia32, __strnlen_ia32_1); \ - __hidden_ver1 (__strnlen_ia32_1, __GI___strnlen, __strnlen_ia32_1); +/* Alias for internal symbol to avoid PLT generation, it redirects the + libc_hidden_def (__strnlen/strlen) to default implementation. */ +__hidden_ver1 (__strnlen_ia32, __GI_strnlen, __strnlen_ia32); +strong_alias (__strnlen_ia32, __strnlen_ia32_1); +__hidden_ver1 (__strnlen_ia32_1, __GI___strnlen, __strnlen_ia32_1); #endif - -#include "string/strnlen.c" diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c b/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c index 957b9b99e8..2ca1cd7181 100644 --- a/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c +++ b/sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c @@ -17,12 +17,12 @@ . */ #define STRNLEN __strnlen_ppc +#include + #ifdef SHARED -# undef libc_hidden_def -# define libc_hidden_def(name) \ - __hidden_ver1 (__strnlen_ppc, __GI_strnlen, __strnlen_ppc); \ - strong_alias (__strnlen_ppc, __strnlen_ppc_1); \ - __hidden_ver1 (__strnlen_ppc_1, __GI___strnlen, __strnlen_ppc_1); +/* Alias for internal symbol to avoid PLT generation, it redirects the + libc_hidden_def (__strnlen/strlen) to default implementation. */ +__hidden_ver1 (__strnlen_ppc, __GI_strnlen, __strnlen_ppc); \ +strong_alias (__strnlen_ppc, __strnlen_ppc_1); \ +__hidden_ver1 (__strnlen_ppc_1, __GI___strnlen, __strnlen_ppc_1); #endif - -#include diff --git a/sysdeps/s390/strnlen-c.c b/sysdeps/s390/strnlen-c.c index 172fcc7caa..95156a0ff5 100644 --- a/sysdeps/s390/strnlen-c.c +++ b/sysdeps/s390/strnlen-c.c @@ -21,14 +21,16 @@ #if HAVE_STRNLEN_C # if HAVE_STRNLEN_IFUNC # define STRNLEN STRNLEN_C +# endif + +# include + +# if HAVE_STRNLEN_IFUNC # if defined SHARED && IS_IN (libc) -# undef libc_hidden_def -# define libc_hidden_def(name) \ - __hidden_ver1 (__strnlen_c, __GI_strnlen, __strnlen_c); \ - strong_alias (__strnlen_c, __strnlen_c_1); \ - __hidden_ver1 (__strnlen_c_1, __GI___strnlen, __strnlen_c_1); +__hidden_ver1 (__strnlen_c, __GI_strnlen, __strnlen_c); +strong_alias (__strnlen_c, __strnlen_c_1); +__hidden_ver1 (__strnlen_c_1, __GI___strnlen, __strnlen_c_1); # endif # endif -# include #endif