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memmove.c
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memmove.c
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/dce.h"
#include "libc/nexgen32e/nexgen32e.h"
#include "libc/nexgen32e/x86feature.h"
#include "libc/str/str.h"
#ifndef __aarch64__
typedef long long xmm_t __attribute__((__vector_size__(16), __aligned__(1)));
typedef long long xmm_a __attribute__((__vector_size__(16), __aligned__(16)));
static __vex void *__memmove(void *dst, const void *src, size_t n) {
char *d;
size_t i;
const char *s;
uint64_t a, b;
xmm_t v, w, x, y, V, W, X, Y;
d = dst;
s = src;
#if defined(__x86_64__) && !defined(__chibicc__)
if (IsTiny()) {
uint16_t w1, w2;
uint32_t l1, l2;
uint64_t q1, q2;
if (n <= 16) {
if (n >= 8) {
__builtin_memcpy(&q1, s, 8);
__builtin_memcpy(&q2, s + n - 8, 8);
__builtin_memcpy(d, &q1, 8);
__builtin_memcpy(d + n - 8, &q2, 8);
} else if (n >= 4) {
__builtin_memcpy(&l1, s, 4);
__builtin_memcpy(&l2, s + n - 4, 4);
__builtin_memcpy(d, &l1, 4);
__builtin_memcpy(d + n - 4, &l2, 4);
} else if (n >= 2) {
__builtin_memcpy(&w1, s, 2);
__builtin_memcpy(&w2, s + n - 2, 2);
__builtin_memcpy(d, &w1, 2);
__builtin_memcpy(d + n - 2, &w2, 2);
} else if (n) {
*d = *s;
}
} else {
if (d <= s) {
asm("rep movsb"
: "+D"(d), "+S"(s), "+c"(n), "=m"(*(char(*)[n])dst)
: "m"(*(char(*)[n])src));
} else {
d += n - 1;
s += n - 1;
asm("std\n\t"
"rep movsb\n\t"
"cld"
: "+D"(d), "+S"(s), "+c"(n), "=m"(*(char(*)[n])dst)
: "m"(*(char(*)[n])src));
}
}
return dst;
}
#endif
switch (n) {
case 0:
return d;
case 1:
*d = *s;
return d;
case 2:
__builtin_memcpy(&a, s, 2);
__builtin_memcpy(d, &a, 2);
return d;
case 3:
__builtin_memcpy(&a, s, 2);
__builtin_memcpy(&b, s + 1, 2);
__builtin_memcpy(d, &a, 2);
__builtin_memcpy(d + 1, &b, 2);
return d;
case 4:
__builtin_memcpy(&a, s, 4);
__builtin_memcpy(d, &a, 4);
return d;
case 5 ... 7:
__builtin_memcpy(&a, s, 4);
__builtin_memcpy(&b, s + n - 4, 4);
__builtin_memcpy(d, &a, 4);
__builtin_memcpy(d + n - 4, &b, 4);
return d;
case 8:
__builtin_memcpy(&a, s, 8);
__builtin_memcpy(d, &a, 8);
return d;
case 9 ... 15:
__builtin_memcpy(&a, s, 8);
__builtin_memcpy(&b, s + n - 8, 8);
__builtin_memcpy(d, &a, 8);
__builtin_memcpy(d + n - 8, &b, 8);
return d;
case 16:
*(xmm_t *)d = *(xmm_t *)s;
return d;
case 17 ... 32:
v = *(xmm_t *)s;
w = *(xmm_t *)(s + n - 16);
*(xmm_t *)d = v;
*(xmm_t *)(d + n - 16) = w;
return d;
case 33 ... 64:
v = *(xmm_t *)s;
w = *(xmm_t *)(s + 16);
x = *(xmm_t *)(s + n - 32);
y = *(xmm_t *)(s + n - 16);
*(xmm_t *)d = v;
*(xmm_t *)(d + 16) = w;
*(xmm_t *)(d + n - 32) = x;
*(xmm_t *)(d + n - 16) = y;
return d;
case 65 ... 127:
v = *(xmm_t *)s;
w = *(xmm_t *)(s + 16);
x = *(xmm_t *)(s + 32);
y = *(xmm_t *)(s + 48);
V = *(xmm_t *)(s + n - 64);
W = *(xmm_t *)(s + n - 48);
X = *(xmm_t *)(s + n - 32);
Y = *(xmm_t *)(s + n - 16);
*(xmm_t *)d = v;
*(xmm_t *)(d + 16) = w;
*(xmm_t *)(d + 32) = x;
*(xmm_t *)(d + 48) = y;
*(xmm_t *)(d + n - 64) = V;
*(xmm_t *)(d + n - 48) = W;
*(xmm_t *)(d + n - 32) = X;
*(xmm_t *)(d + n - 16) = Y;
return d;
default:
if (d == s)
return d;
#if defined(__x86_64__) && !defined(__chibicc__)
if (n < kHalfCache3 || !kHalfCache3) {
if (d > s) {
if (n < 900 || !X86_HAVE(ERMS)) {
do {
n -= 32;
v = *(const xmm_t *)(s + n);
w = *(const xmm_t *)(s + n + 16);
*(xmm_t *)(d + n) = v;
*(xmm_t *)(d + n + 16) = w;
} while (n >= 32);
} else {
asm("std\n\t"
"rep movsb\n\t"
"cld"
: "=D"(d), "=S"(s), "+c"(n), "=m"(*(char(*)[n])d)
: "0"(d + n - 1), "1"(s + n - 1), "m"(*(char(*)[n])s));
return dst;
}
} else {
if (n < 900 || !X86_HAVE(ERMS)) {
i = 0;
do {
v = *(const xmm_t *)(s + i);
w = *(const xmm_t *)(s + i + 16);
*(xmm_t *)(d + i) = v;
*(xmm_t *)(d + i + 16) = w;
} while ((i += 32) + 32 <= n);
d += i;
s += i;
n -= i;
} else {
asm("rep movsb"
: "+D"(d), "+S"(s), "+c"(n), "=m"(*(char(*)[n])d)
: "m"(*(char(*)[n])s));
return dst;
}
}
} else {
if (d > s) {
while ((uintptr_t)(d + n) & 15) {
--n;
d[n] = s[n];
}
do {
n -= 32;
v = *(const xmm_t *)(s + n);
w = *(const xmm_t *)(s + n + 16);
__builtin_ia32_movntdq((xmm_a *)(d + n), v);
__builtin_ia32_movntdq((xmm_a *)(d + n + 16), w);
} while (n >= 32);
} else {
i = 0;
while ((uintptr_t)(d + i) & 15) {
d[i] = s[i];
++i;
}
do {
v = *(const xmm_t *)(s + i);
w = *(const xmm_t *)(s + i + 16);
__builtin_ia32_movntdq((xmm_a *)(d + i), v);
__builtin_ia32_movntdq((xmm_a *)(d + i + 16), w);
} while ((i += 32) + 32 <= n);
d += i;
s += i;
n -= i;
}
asm("sfence");
}
#else
if (d > s) {
do {
n -= 32;
v = *(const xmm_t *)(s + n);
w = *(const xmm_t *)(s + n + 16);
*(xmm_t *)(d + n) = v;
*(xmm_t *)(d + n + 16) = w;
} while (n >= 32);
} else {
i = 0;
do {
v = *(const xmm_t *)(s + i);
w = *(const xmm_t *)(s + i + 16);
*(xmm_t *)(d + i) = v;
*(xmm_t *)(d + i + 16) = w;
} while ((i += 32) + 32 <= n);
d += i;
s += i;
n -= i;
}
#endif
if (n) {
if (n >= 16) {
v = *(const xmm_t *)s;
w = *(const xmm_t *)(s + n - 16);
*(xmm_t *)d = v;
*(xmm_t *)(d + n - 16) = w;
} else if (n >= 8) {
__builtin_memcpy(&a, s, 8);
__builtin_memcpy(&b, s + n - 8, 8);
__builtin_memcpy(d, &a, 8);
__builtin_memcpy(d + n - 8, &b, 8);
} else if (n >= 4) {
__builtin_memcpy(&a, s, 4);
__builtin_memcpy(&b, s + n - 4, 4);
__builtin_memcpy(d, &a, 4);
__builtin_memcpy(d + n - 4, &b, 4);
} else if (n >= 2) {
__builtin_memcpy(&a, s, 2);
__builtin_memcpy(&b, s + n - 2, 2);
__builtin_memcpy(d, &a, 2);
__builtin_memcpy(d + n - 2, &b, 2);
} else {
*d = *s;
}
}
return dst;
}
}
/**
* Copies memory.
*
* memmove n=0 661 picoseconds
* memmove n=1 661 ps/byte 1,476 mb/s
* memmove n=2 330 ps/byte 2,952 mb/s
* memmove n=3 330 ps/byte 2,952 mb/s
* memmove n=4 165 ps/byte 5,904 mb/s
* memmove n=7 141 ps/byte 6,888 mb/s
* memmove n=8 82 ps/byte 11 GB/s
* memmove n=15 44 ps/byte 21 GB/s
* memmove n=16 41 ps/byte 23 GB/s
* memmove n=31 32 ps/byte 29 GB/s
* memmove n=32 31 ps/byte 30 GB/s
* memmove n=63 21 ps/byte 45 GB/s
* memmove n=64 15 ps/byte 61 GB/s
* memmove n=127 13 ps/byte 73 GB/s
* memmove n=128 31 ps/byte 30 GB/s
* memmove n=255 20 ps/byte 45 GB/s
* memmove n=256 19 ps/byte 49 GB/s
* memmove n=511 16 ps/byte 56 GB/s
* memmove n=512 17 ps/byte 54 GB/s
* memmove n=1023 18 ps/byte 52 GB/s
* memmove n=1024 13 ps/byte 72 GB/s
* memmove n=2047 9 ps/byte 96 GB/s
* memmove n=2048 9 ps/byte 98 GB/s
* memmove n=4095 8 ps/byte 112 GB/s
* memmove n=4096 8 ps/byte 109 GB/s
* memmove n=8191 7 ps/byte 124 GB/s
* memmove n=8192 7 ps/byte 125 GB/s
* memmove n=16383 7 ps/byte 134 GB/s
* memmove n=16384 7 ps/byte 134 GB/s
* memmove n=32767 13 ps/byte 72 GB/s
* memmove n=32768 13 ps/byte 72 GB/s
* memmove n=65535 13 ps/byte 68 GB/s
* memmove n=65536 14 ps/byte 67 GB/s
* memmove n=131071 14 ps/byte 65 GB/s
* memmove n=131072 14 ps/byte 64 GB/s
* memmove n=262143 15 ps/byte 63 GB/s
* memmove n=262144 15 ps/byte 63 GB/s
* memmove n=524287 15 ps/byte 61 GB/s
* memmove n=524288 15 ps/byte 61 GB/s
* memmove n=1048575 15 ps/byte 61 GB/s
* memmove n=1048576 15 ps/byte 61 GB/s
* memmove n=2097151 19 ps/byte 48 GB/s
* memmove n=2097152 27 ps/byte 35 GB/s
* memmove n=4194303 28 ps/byte 33 GB/s
* memmove n=4194304 28 ps/byte 33 GB/s
* memmove n=8388607 28 ps/byte 33 GB/s
* memmove n=8388608 28 ps/byte 33 GB/s
*
* DST and SRC may overlap.
*
* @param dst is destination
* @param src is memory to copy
* @param n is number of bytes to copy
* @return dst
* @asyncsignalsafe
*/
void *memmove(void *dst, const void *src, size_t n) {
return __memmove(dst, src, n);
}
__weak_reference(memmove, memcpy);
#endif /* __aarch64__ */