mirror of
https://github.com/jart/cosmopolitan.git
synced 2024-05-16 18:42:39 +00:00
2ab9e9f7fd
- Introduce portable sched_getcpu() api - Support GCC's __target_clones__ feature - Make fma() go faster on x86 in default mode - Remove some asan checks from core libraries - WinMain() now ensures $HOME and $USER are defined
60 lines
2.9 KiB
C
60 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/dce.h"
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#include "libc/str/str.h"
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#ifndef __aarch64__
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/**
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* Returns length of NUL-terminated string.
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*
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* @param s is non-null NUL-terminated string pointer
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* @return number of bytes (excluding NUL)
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* @asyncsignalsafe
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*/
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size_t strlen(const char *s) {
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#if defined(__x86_64__) && !defined(__chibicc__)
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typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(16)));
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xmm_t z = {0};
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unsigned m, k = (uintptr_t)s & 15;
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const xmm_t *p = (const xmm_t *)((uintptr_t)s & -16);
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m = __builtin_ia32_pmovmskb128(*p == z) >> k << k;
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while (!m) m = __builtin_ia32_pmovmskb128(*++p == z);
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return (const char *)p + __builtin_ctzl(m) - s;
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#else
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#define ONES ((word) - 1 / 255)
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#define BANE (ONES * (255 / 2 + 1))
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typedef unsigned long mayalias word;
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word w;
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unsigned k;
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const word *p;
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k = (uintptr_t)s & (sizeof(word) - 1);
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p = (const word *)((uintptr_t)s & -sizeof(word));
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w = *p;
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w = ~w & (w - ONES) & BANE;
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w >>= k << 3;
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w <<= k << 3;
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while (!w) {
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w = *++p;
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w = ~w & (w - ONES) & BANE;
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}
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return (const char *)p + (__builtin_ctzl(w) >> 3) - s;
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#endif
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}
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#endif /* __aarch64__ */
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