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1faccf388a
The libm size improvement built with gcc-14, "--enable-stack-protector=strong --enable-bind-now=yes --enable-fortify-source=2": Before: text data bss dec hex filename 583444 844 12 584300 8ea6c aarch64-linux-gnu/math/libm.so 976349 1076 12 977437 eea1d x86_64-linux-gnu/math/libm.so 1204738 5608 368 1210714 12795a powerpc64le-linux-gnu/math/libm.so After: 582292 844 12 583148 8e5ec aarch64-linux-gnu/math/libm.so 975133 1076 12 976221 ee55d x86_64-linux-gnu/math/libm.so 1203586 5608 368 1209562 1274da powerpc64le-linux-gnu/math/libm.so Reviewed-by: Andreas K. Huettel <dilfridge@gentoo.org>
89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
/* Correctly-rounded half-revolution arc-cosine function for binary32 value.
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Copyright (c) 2022-2025 Alexei Sibidanov.
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The original version of this file was copied from the CORE-MATH
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project (file src/binary32/acospi/acospif.c, revision 1a6a9ab).
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#include <math.h>
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#include <stdint.h>
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#include <libm-alias-float.h>
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#include "math_config.h"
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#include "s_asincospif_data.h"
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float
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__acospif (float x)
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{
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float ax = fabsf (x);
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double az = ax;
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double z = x;
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uint32_t t = asuint (x);
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int e = (t >> 23) & 0xff;
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if (__glibc_unlikely (e >= 127))
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{
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if (x == 1.0f)
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return 0.0f;
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if (x == -1.0f)
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return 1.0f;
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if (e == 0xff && (t << 9))
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return x + x; /* nan */
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return __math_edomf ((x - x) / (x - x)); /* nan */
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}
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int s = 146 - e;
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int i = 0;
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if (__glibc_likely (s < 32))
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i = ((t & (~0u >> 9)) | 1 << 23) >> s;
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const double *c = CH[i];
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double z2 = z * z;
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double z4 = z2 * z2;
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if (__glibc_unlikely (i == 0))
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{
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double c0 = c[0] + z2 * c[1];
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double c2 = c[2] + z2 * c[3];
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double c4 = c[4] + z2 * c[5];
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double c6 = c[6] + z2 * c[7];
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c0 += c2 * z4;
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c4 += c6 * z4;
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/* For |x| <= 0x1.0fd288p-127, c0 += c4*(z4*z4) would raise a spurious
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underflow exception, we use an FMA instead, where c4 * z4 does not
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underflow. */
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c0 = fma (c4 * z4, z4, c0);
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return 0.5 - z * c0;
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}
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else
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{
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double f = sqrt (1 - az);
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double c0 = c[0] + az * c[1];
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double c2 = c[2] + az * c[3];
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double c4 = c[4] + az * c[5];
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double c6 = c[6] + az * c[7];
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c0 += c2 * z2;
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c4 += c6 * z2;
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c0 += c4 * z4;
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static const double o[] = { 0, 1 };
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double r = o[t >> 31] + c0 * copysign (f, x);
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return r;
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}
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}
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libm_alias_float (__acospi, acospi)
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