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nir: implement lowering for fsin and fcos 

Lower sin and cos using Nick's fast sin/cos approximation from
https://web.archive.org/web/20180105155939/http://forum.devmaster.net/t/fast-and-accurate-sine-cosine/9648

It's suitable for GLES2, but it throws warnings in dEQP GLES3 precision tests.

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Qiang Yu <yuq825@gmail.com>
Tested-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
This commit is contained in:
Vasily Khoruzhick 2019-04-07 13:24:45 -07:00 committed by Erico Nunes
parent b15c46e6bf
commit e67e4e90b2
4 changed files with 142 additions and 0 deletions
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1
src/compiler/Makefile.sources
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@ -269,6 +269,7 @@ NIR_FILES = \
nir/nir_lower_regs_to_ssa.c \
nir/nir_lower_returns.c \
nir/nir_lower_scratch.c \
nir/nir_lower_sincos.c \
nir/nir_lower_subgroups.c \
nir/nir_lower_system_values.c \
nir/nir_lower_tex.c \

1
src/compiler/nir/meson.build
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@ -150,6 +150,7 @@ files_libnir = files(
'nir_lower_returns.c',
'nir_lower_scratch.c',
'nir_lower_subgroups.c',
'nir_lower_sincos.c',
'nir_lower_system_values.c',
'nir_lower_tex.c',
'nir_lower_to_source_mods.c',

2
src/compiler/nir/nir.h
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@ -3554,6 +3554,8 @@ uint64_t nir_get_single_slot_attribs_mask(uint64_t attribs, uint64_t dual_slot);
nir_intrinsic_op nir_intrinsic_from_system_value(gl_system_value val);
gl_system_value nir_system_value_from_intrinsic(nir_intrinsic_op intrin);
bool nir_lower_sincos(nir_shader *shader);
#ifdef __cplusplus
} /* extern "C" */
#endif

138
src/compiler/nir/nir_lower_sincos.c Normal file
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@ -0,0 +1,138 @@
/*
* Copyright (c) 2014 Scott Mansell
* Copyright © 2014 Broadcom
* Copyright (c) 2019 Vasily Khoruzhick <anarsoul@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "util/u_math.h"
#include "nir.h"
#include "nir_builder.h"
static nir_ssa_def *
shrink_input(nir_builder *b, nir_ssa_def *x)
{
nir_ssa_def *scaled_x = nir_fmul_imm(b, x, 1.0 / (M_PI * 2));
nir_ssa_def *xfrac = nir_ffract(b, scaled_x);
/* Map [0.5, 1] to [-0.5, 0] */
nir_ssa_def *xfrac_0_5_1 = nir_fadd_imm(b, xfrac, -1.0);
/* Map [-1, -0.5] to [0, 0.5] */
nir_ssa_def *xfrac_n1_n0_5 = nir_fadd_imm(b, xfrac, 1.0);
nir_ssa_def *geq_0_5 = nir_build_alu(b, nir_op_fge, xfrac, nir_imm_float(b, 0.5), NULL, NULL);
nir_ssa_def *less_m0_5 = nir_build_alu(b, nir_op_flt, xfrac, nir_imm_float(b, -0.5), NULL, NULL);
nir_ssa_def *sel1 = nir_build_alu(b, nir_op_bcsel, geq_0_5, xfrac_0_5_1, xfrac, NULL );
nir_ssa_def *sel2 = nir_build_alu(b, nir_op_bcsel, less_m0_5, xfrac_n1_n0_5, sel1, NULL);
return sel2;
}
static nir_ssa_def *
lower_sincos(nir_builder *b, nir_ssa_def *src, bool do_cos)
{
/* Fast sin/cos implementation, see
* https://web.archive.org/web/20180105155939/http://forum.devmaster.net/t/fast-and-accurate-sine-cosine/9648
*/
const float B = 8.0; //(M_PI * 2.0) * (4.0 / M_PI);
const float C = -16.0; //(M_PI * 2.0) * (M_PI * 2.0) * (-4.0 / (M_PI * M_PI));
const float P = 0.225;
if (do_cos)
src = nir_fadd_imm(b, src, M_PI / 2.0);
nir_ssa_def *x = shrink_input(b, src);
nir_ssa_def *bx = nir_fmul_imm(b, x, B);
nir_ssa_def *cx = nir_fmul_imm(b, x, C);
nir_ssa_def *absx = nir_fabs(b, x);
nir_ssa_def *cxabsx = nir_fmul(b, cx, absx);
/* Y1 = B * x + C * x * fabs(x) */
nir_ssa_def *y1 = nir_fadd(b, bx, cxabsx);
/* Precision step: Y = P * (Y1 * fabs(Y1) - Y1) + Y1 */
nir_ssa_def *y = nir_fabs(b, y1);
y = nir_fmul(b, y, y1);
y = nir_fsub(b, y, y1);
y = nir_fmul_imm(b, y, P);
y = nir_fadd(b, y, y1);
return y;
}
static bool
lower_sincos_impl(nir_function_impl *impl)
{
bool progress = false;
nir_builder b;
nir_builder_init(&b, impl);
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_alu)
continue;
nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
nir_ssa_def *lower;
b.cursor = nir_before_instr(instr);
switch (alu_instr->op) {
case nir_op_fsin:
lower = lower_sincos(&b, nir_ssa_for_alu_src(&b, alu_instr, 0), false);
break;
case nir_op_fcos:
lower = lower_sincos(&b, nir_ssa_for_alu_src(&b, alu_instr, 0), true);
break;
default:
continue;
}
nir_ssa_def_rewrite_uses(&alu_instr->dest.dest.ssa,
nir_src_for_ssa(lower));
nir_instr_remove(instr);
progress = true;
}
}
if (progress) {
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
}
return progress;
}
bool
nir_lower_sincos(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl)
progress |= lower_sincos_impl(function->impl);
}
return progress;
}