From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa1-x2b.google.com (mail-oa1-x2b.google.com [IPv6:2001:4860:4864:20::2b]) by sourceware.org (Postfix) with ESMTPS id 6D31C3858D39 for ; Fri, 2 Sep 2022 20:39:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6D31C3858D39 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=linaro.org Received: by mail-oa1-x2b.google.com with SMTP id 586e51a60fabf-11eb8b133fbso7745340fac.0 for ; Fri, 02 Sep 2022 13:39:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=viMCbP1twviKtZZ7XoNUfVEr0XKnr17fE+NtQp0yO+Q=; b=K4hVJu+QNVQrVJA+ippMrDme0V+UCyqeMnnmcyWexkPsU+2pqwFttlOqyrrZlSsnsu /Y7mNzE93t87lg5jeeFa0I4HpUfejWTLIk422tzU6oP6ZrcxQVRbzEedEP5aXk5x4hz2 TFc2lPTlCSQRunmrLeMTBnzGvEB/vTIFf74t0LaniTvQgkybpmbN5z+tJSveyaEvUTQq crdS+qu7okdYPf1DArIjisvGayqGHft5O91IggKkVd2UXc1LEgt/3a/obpVBzWhADL2B 30yEEo5XvZaM/ozpRH4XSYFHxBqGu+TRoc9OQsmHrD320k2/DGai6qQX9BbCpGmLp5AA WYlA== 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:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=viMCbP1twviKtZZ7XoNUfVEr0XKnr17fE+NtQp0yO+Q=; b=venInNMlao5beVYyQX7u7WMWsoIetvInuoHkH/9jlASvctK509wr80bXFj9V3L6S8f znWDYgzy75UoaiOJ4nA8kewoBXhTatUwNl8vxk+PI5ifCiY0RGly3o+g4o0oqswh3I0q 4P2+sJ9Bre9pA+EooOgv+Key+ubB0K0nH/t1X5/oxC4cgZjiNzVdzsTNIcskRx67kEDi B2lVM0XcOAdSDqCE009l/d3X9RDtT/MUqkgc8ZHSgDIVfeUiJmJ8AVvUZfvs8lXL7iMO JgLWMdROZs8KxDc5dIk2XgvwpuEA+LZ1HxDEyObNrQRgHKv7fxrj7dvaINdmL3tXxkWm Ulxw== X-Gm-Message-State: ACgBeo2wE3bY+InMsTc8rRorYUNuPrwSUf1G4k6+qwX1EwnjJWEVXO7N EJfOICS2W/jYJEWiBvhPENrOK9L3X3YXxg== X-Google-Smtp-Source: AA6agR7Whw1zS+lqSjLt+B25oA+zAIoES53tbgTo+qclHxD0du8elG5o2zdl8uABMhp19F7lHWI/kg== X-Received: by 2002:a05:6870:2193:b0:125:5155:7330 with SMTP id l19-20020a056870219300b0012551557330mr2035078oae.280.1662151194584; Fri, 02 Sep 2022 13:39:54 -0700 (PDT) Received: from mandiga.. ([2804:1b3:a7c0:dfed:72d1:946c:4eb1:ce5f]) by smtp.gmail.com with ESMTPSA id i27-20020a4a6f5b000000b00425678b9c4bsm1107902oof.0.2022.09.02.13.39.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Sep 2022 13:39:54 -0700 (PDT) From: Adhemerval Zanella To: libc-alpha@sourceware.org Cc: Joseph Myers , caiyinyu , Richard Henderson Subject: [PATCH 05/17] string: Improve generic strlen Date: Fri, 2 Sep 2022 17:39:28 -0300 Message-Id: <20220902203940.2385967-6-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220902203940.2385967-1-adhemerval.zanella@linaro.org> References: <20220902203940.2385967-1-adhemerval.zanella@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE 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: New algorithm have the following key differences: - Reads first word unaligned and use string-maskoff functions to remove unwanted data. This strategy follow arch-specific optimization used on powerpc, sparc, and SH. - Use of has_zero and index_first_zero parametrized functions. Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc-linux-gnu, and powercp64-linux-gnu by removing the arch-specific assembly implementation and disabling multi-arch (it covers both LE and BE for 64 and 32 bits). Co-authored-by: Richard Henderson --- string/strlen.c | 90 +++++++++-------------------------------- sysdeps/s390/strlen-c.c | 10 +++-- 2 files changed, 26 insertions(+), 74 deletions(-) diff --git a/string/strlen.c b/string/strlen.c index 54f3fb8167..ed71c22414 100644 --- a/string/strlen.c +++ b/string/strlen.c @@ -17,84 +17,34 @@ #include #include - -#undef strlen - -#ifndef STRLEN -# define STRLEN strlen +#include +#include +#include +#include +#include + +#ifdef STRLEN +# define __strlen STRLEN #endif /* Return the length of the null-terminated string STR. Scan for the null terminator quickly by testing four bytes at a time. */ size_t -STRLEN (const char *str) +__strlen (const char *str) { - const char *char_ptr; - const unsigned long int *longword_ptr; - unsigned long int longword, himagic, lomagic; - - /* 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; - - /* All these elucidatory comments refer to 4-byte longwords, - but the theory applies equally well to 8-byte longwords. */ + /* Align pointer to sizeof op_t. */ + const uintptr_t s_int = (uintptr_t) str; + const op_t *word_ptr = word_containing (str); - longword_ptr = (unsigned long int *) char_ptr; + /* Read and MASK the first word. */ + op_t word = *word_ptr | create_mask (s_int); - /* Computing (longword - lomagic) sets the high bit of any corresponding - byte that is either zero or greater than 0x80. The latter case can be - filtered out by computing (~longword & himagic). The final result - will always be non-zero if one of the bytes of longword is zero. */ - 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 (); + while (! has_zero (word)) + word = *++word_ptr; - /* 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? */ - - 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; } +#ifndef STRLEN +weak_alias (__strlen, strlen) libc_hidden_builtin_def (strlen) +#endif diff --git a/sysdeps/s390/strlen-c.c b/sysdeps/s390/strlen-c.c index c96767e329..06413c9a57 100644 --- a/sysdeps/s390/strlen-c.c +++ b/sysdeps/s390/strlen-c.c @@ -21,12 +21,14 @@ #if HAVE_STRLEN_C # if HAVE_STRLEN_IFUNC # define STRLEN STRLEN_C +# endif + +# include + +# if HAVE_STRLEN_IFUNC # if defined SHARED && IS_IN (libc) -# undef libc_hidden_builtin_def -# define libc_hidden_builtin_def(name) \ - __hidden_ver1 (__strlen_c, __GI_strlen, __strlen_c); +__hidden_ver1 (__strlen_c, __GI_strlen, __strlen_c); # endif # endif -# include #endif -- 2.34.1