76 lines
3.0 KiB
C
76 lines
3.0 KiB
C
/*
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* Copyright © 2020 Microsoft Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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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
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* THE 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
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include "nir.h"
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#include "nir_builder.h"
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static bool
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nir_scale_fdiv_instr(nir_builder *b, nir_instr *instr, UNUSED void *_data)
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{
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if (instr->type != nir_instr_type_alu)
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return false;
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nir_alu_instr *alu = nir_instr_as_alu(instr);
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if (alu->op != nir_op_fdiv || alu->src[0].src.ssa->bit_size != 32)
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return false;
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b->cursor = nir_before_instr(&alu->instr);
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nir_ssa_def *fabs = nir_fabs(b, alu->src[1].src.ssa);
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nir_ssa_def *big = nir_flt(b, nir_imm_int(b, 0x7e800000), fabs);
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nir_ssa_def *small = nir_flt(b, fabs, nir_imm_int(b, 0x00800000));
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nir_ssa_def *scaled_down_a = nir_fmul_imm(b, alu->src[0].src.ssa, 0.25);
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nir_ssa_def *scaled_down_b = nir_fmul_imm(b, alu->src[1].src.ssa, 0.25);
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nir_ssa_def *scaled_up_a = nir_fmul_imm(b, alu->src[0].src.ssa, 16777216.0);
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nir_ssa_def *scaled_up_b = nir_fmul_imm(b, alu->src[1].src.ssa, 16777216.0);
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nir_ssa_def *final_a =
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nir_bcsel(b, big, scaled_down_a,
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(nir_bcsel(b, small, scaled_up_a, alu->src[0].src.ssa)));
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nir_ssa_def *final_b =
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nir_bcsel(b, big, scaled_down_b,
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(nir_bcsel(b, small, scaled_up_b, alu->src[1].src.ssa)));
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nir_instr_rewrite_src_ssa(instr, &alu->src[0].src, final_a);
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nir_instr_rewrite_src_ssa(instr, &alu->src[1].src, final_b);
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return true;
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}
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/** Scale both sides of an fdiv if needed to prevent denorm flushing
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*
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* This may be needed to satisfy the precision requirements of OpenCL. When
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* fdiv is lowered to frcp+fmul, denorm flushing may cause the frcp to return
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* zero even for finite floats. This multiplies both sides of an fdiv by a
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* constant, if needed, to prevent such flushing.
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*/
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bool
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nir_scale_fdiv(nir_shader *shader)
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{
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return nir_shader_instructions_pass(shader, nir_scale_fdiv_instr,
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nir_metadata_block_index |
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nir_metadata_dominance,
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NULL);
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}
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