mirror of https://gitlab.freedesktop.org/mesa/mesa
65 lines
2.5 KiB
C
65 lines
2.5 KiB
C
/*
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* Copyright (C) 2019 Collabora, Ltd.
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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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* Authors (Collabora):
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* Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
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*/
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/**
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* @file
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*
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* Flushes undefined SSA values to a zero vector fo the appropriate component
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* count, to avoid undefined behaviour in the resulting shader. Not required
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* for conformance as use of uninitialized variables is explicitly left
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* undefined by the spec. Works around buggy apps, however.
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*
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* Call immediately after nir_opt_undef. If called before, larger optimization
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* opportunities from the former pass will be missed. If called outside of an
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* optimization loop, constant propagation and algebraic optimizations won't be
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* able to kick in to reduce stuff consuming the zero.
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*/
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#include "nir_builder.h"
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static bool
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lower_undef_instr_to_zero(nir_builder *b, nir_instr *instr, UNUSED void *_state)
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{
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if (instr->type != nir_instr_type_undef)
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return false;
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nir_undef_instr *und = nir_instr_as_undef(instr);
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b->cursor = nir_instr_remove(&und->instr);
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nir_def *zero = nir_imm_zero(b, und->def.num_components,
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und->def.bit_size);
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nir_def_rewrite_uses(&und->def, zero);
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return true;
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}
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bool
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nir_lower_undef_to_zero(nir_shader *shader)
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{
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return nir_shader_instructions_pass(shader, lower_undef_instr_to_zero,
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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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