mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-13 23:00:22 +00:00
b0e0a07018
This includes a fix for big-endian in AdvSIMD log, some cosmetic
changes, and numerous small optimisations mainly around inlining and
using indexed variants of MLA intrinsics.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit e302e10213)
78 lines
2.7 KiB
C
78 lines
2.7 KiB
C
/* Single-precision vector (SVE) exp2 function
|
|
|
|
Copyright (C) 2023-2024 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include "sv_math.h"
|
|
#include "poly_sve_f32.h"
|
|
|
|
#define Thres 0x1.5d5e2ap+6f
|
|
|
|
static const struct data
|
|
{
|
|
float poly[5];
|
|
float shift, thres;
|
|
} data = {
|
|
/* Coefficients copied from the polynomial in AdvSIMD variant, reversed for
|
|
compatibility with polynomial helpers. */
|
|
.poly = { 0x1.62e422p-1f, 0x1.ebf9bcp-3f, 0x1.c6bd32p-5f, 0x1.3ce9e4p-7f,
|
|
0x1.59977ap-10f },
|
|
/* 1.5*2^17 + 127. */
|
|
.shift = 0x1.903f8p17f,
|
|
/* Roughly 87.3. For x < -Thres, the result is subnormal and not handled
|
|
correctly by FEXPA. */
|
|
.thres = Thres,
|
|
};
|
|
|
|
static svfloat32_t NOINLINE
|
|
special_case (svfloat32_t x, svfloat32_t y, svbool_t special)
|
|
{
|
|
return sv_call_f32 (exp2f, x, y, special);
|
|
}
|
|
|
|
/* Single-precision SVE exp2f routine. Implements the same algorithm
|
|
as AdvSIMD exp2f.
|
|
Worst case error is 1.04 ULPs.
|
|
SV_NAME_F1 (exp2)(0x1.943b9p-1) got 0x1.ba7eb2p+0
|
|
want 0x1.ba7ebp+0. */
|
|
svfloat32_t SV_NAME_F1 (exp2) (svfloat32_t x, const svbool_t pg)
|
|
{
|
|
const struct data *d = ptr_barrier (&data);
|
|
/* exp2(x) = 2^n (1 + poly(r)), with 1 + poly(r) in [1/sqrt(2),sqrt(2)]
|
|
x = n + r, with r in [-1/2, 1/2]. */
|
|
svfloat32_t shift = sv_f32 (d->shift);
|
|
svfloat32_t z = svadd_x (pg, x, shift);
|
|
svfloat32_t n = svsub_x (pg, z, shift);
|
|
svfloat32_t r = svsub_x (pg, x, n);
|
|
|
|
svbool_t special = svacgt (pg, x, d->thres);
|
|
svfloat32_t scale = svexpa (svreinterpret_u32 (z));
|
|
|
|
/* Polynomial evaluation: poly(r) ~ exp2(r)-1.
|
|
Evaluate polynomial use hybrid scheme - offset ESTRIN by 1 for
|
|
coefficients 1 to 4, and apply most significant coefficient directly. */
|
|
svfloat32_t r2 = svmul_x (pg, r, r);
|
|
svfloat32_t p14 = sv_pairwise_poly_3_f32_x (pg, r, r2, d->poly + 1);
|
|
svfloat32_t p0 = svmul_x (pg, r, d->poly[0]);
|
|
svfloat32_t poly = svmla_x (pg, p0, r2, p14);
|
|
|
|
if (__glibc_unlikely (svptest_any (pg, special)))
|
|
return special_case (x, svmla_x (pg, scale, scale, poly), special);
|
|
|
|
return svmla_x (pg, scale, scale, poly);
|
|
}
|