122 lines
4.7 KiB
C
122 lines
4.7 KiB
C
/*
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* Copyright © 2017 Broadcom
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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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/**
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* @file
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*
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* Implements GL alpha testing by comparing the output color's alpha to the
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* alpha_ref intrinsic and emitting a discard based on it.
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*
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* The alpha_to_one value overrides the source alpha to 1.0 to implement
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* GL_SAMPLE_ALPHA_TO_ONE, which applies before the alpha test (and would be
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* rather silly to use with alpha test, but the spec permits).
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*/
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#include "nir/nir.h"
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#include "nir/nir_builder.h"
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void
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nir_lower_alpha_test(nir_shader *shader, enum compare_func func,
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bool alpha_to_one,
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const gl_state_index16 *alpha_ref_state_tokens)
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{
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assert(alpha_ref_state_tokens);
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assert(shader->info.stage == MESA_SHADER_FRAGMENT);
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nir_foreach_function(function, shader) {
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nir_function_impl *impl = function->impl;
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nir_builder b;
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nir_builder_init(&b, impl);
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b.cursor = nir_before_cf_list(&impl->body);
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nir_foreach_block(block, impl) {
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nir_foreach_instr_safe(instr, block) {
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if (instr->type == nir_instr_type_intrinsic) {
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nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
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nir_variable *out = NULL;
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switch (intr->intrinsic) {
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case nir_intrinsic_store_deref:
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out = nir_deref_instr_get_variable(nir_src_as_deref(intr->src[0]));
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break;
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case nir_intrinsic_store_output:
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/* already had i/o lowered.. lookup the matching output var: */
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nir_foreach_shader_out_variable(var, shader) {
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int drvloc = var->data.driver_location;
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if (nir_intrinsic_base(intr) == drvloc) {
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out = var;
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break;
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}
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}
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assume(out);
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break;
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default:
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continue;
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}
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if (out->data.mode != nir_var_shader_out)
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continue;
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if (out->data.location != FRAG_RESULT_COLOR &&
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out->data.location != FRAG_RESULT_DATA0)
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continue;
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b.cursor = nir_before_instr(&intr->instr);
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nir_ssa_def *alpha;
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if (alpha_to_one) {
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alpha = nir_imm_float(&b, 1.0);
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} else if (intr->intrinsic == nir_intrinsic_store_deref) {
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alpha = nir_channel(&b, nir_ssa_for_src(&b, intr->src[1], 4),
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3);
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} else {
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alpha = nir_channel(&b, nir_ssa_for_src(&b, intr->src[0], 4),
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3);
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}
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nir_variable *var = nir_variable_create(shader,
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nir_var_uniform,
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glsl_float_type(),
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"gl_AlphaRefMESA");
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var->num_state_slots = 1;
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var->state_slots = ralloc_array(var, nir_state_slot, 1);
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memcpy(var->state_slots[0].tokens,
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alpha_ref_state_tokens,
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sizeof(var->state_slots[0].tokens));
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nir_ssa_def *alpha_ref = nir_load_var(&b, var);
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nir_ssa_def *condition =
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nir_compare_func(&b, func, alpha, alpha_ref);
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nir_discard_if(&b, nir_inot(&b, condition));
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shader->info.fs.uses_discard = true;
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}
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}
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}
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nir_metadata_preserve(impl, nir_metadata_block_index |
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nir_metadata_dominance);
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}
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}
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