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Remove division from matrix multiplication

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This change reduces llama.com CPU cycles systemically by 2.5% according
to the Linux Kernel `perf stat -Bddd` utility.
This commit is contained in:
Justine Tunney 2023-05-10 21:19:54 -07:00
parent a88290e595
commit 1f6f9e6701
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GPG key ID: BE714B4575D6E328
7 changed files with 191 additions and 70 deletions
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52
test/libc/tinymath/magicu_test.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2023 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/tinymath/magicu.h"
#include "libc/macros.internal.h"
#include "libc/testlib/ezbench.h"
#include "libc/testlib/testlib.h"
#define T uint32_t
#define TBIT (sizeof(T) * CHAR_BIT - 1)
#define TMIN (((T) ~(T)0) > 1 ? (T)0 : (T)((uintmax_t)1 << TBIT))
#define TMAX (((T) ~(T)0) > 1 ? (T) ~(T)0 : (T)(((uintmax_t)1 << TBIT) - 1))
T V[] = {5, 4, 77, 4, 7, 0,
1, 2, 3, 4, -1, -2,
-3, -4, TMIN, TMIN + 1, TMIN + 2, TMIN + 3,
TMIN + 5, TMIN + 7, TMAX, TMAX - 1, TMAX - 2, TMAX - 77,
TMAX - 3, TMAX - 5, TMAX - 7, TMAX - 50, TMIN / 2, TMAX / 2,
TMAX / 2 - 3};
TEST(magicu, test) {
int i, j;
for (i = 0; i < ARRAYLEN(V); ++i) {
if (!V[i]) continue;
struct magicu d = __magicu_get(V[i]);
for (j = 0; j < ARRAYLEN(V); ++j) {
EXPECT_EQ(V[j] / V[i], __magicu_div(V[j], d));
}
}
}
BENCH(cog, bench) {
struct magicu d = __magicu_get(7);
EZBENCH2("__magicu_get", donothing, __magicu_get(VEIL("r", 77)));
EZBENCH2("__magicu_div", donothing,
EXPROPRIATE(__magicu_div(VEIL("r", 77), d)));
EZBENCH2("/", donothing, EXPROPRIATE(VEIL("r", 77) / VEIL("r", 7)));
}