Ian Romanick
d7ba52cce9
Most modern hardware needs the edge flag added as a hidden vertex input and needs code added to the vertex shader to copy the input to an output. Intel hardware is a little different. Gfx4 and Gfx5 hardware works in the previously described mannter. Gfx6+ hardware needs the edge flag as a specific vertex shader input, and that input is magically processed by fixed-function hardware without need for extra shader code. This flag signals only that the vertex shader input is needed. It would be nice if we could decouple adding the vertex shader input from generating the copy-to-output code, but that has proven to be challenging. Not having that code causes other passes to want to eliminate that shader input. v2: Convert conditional to assertion. This pass is only called for vertex shaders. Suggested by Ken. Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12858>
105 lines
3.7 KiB
C
105 lines
3.7 KiB
C
/*
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* Copyright © 2015 Red Hat
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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 FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* 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 void
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lower_impl(nir_function_impl *impl)
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{
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nir_shader *shader = impl->function->shader;
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nir_builder b;
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nir_variable *in, *out;
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nir_ssa_def *def;
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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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/* The edge flag is the last input in st/mesa. This code is also called by
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* i965 which calls it before any input locations are assigned.
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*/
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assert(shader->num_inputs == 0 ||
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shader->num_inputs == util_bitcount64(shader->info.inputs_read));
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/* Lowered IO only uses intrinsics. It doesn't use variables. */
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if (shader->info.io_lowered) {
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assert(shader->num_outputs ==
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util_bitcount64(shader->info.outputs_written));
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/* Load an edge flag. */
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nir_io_semantics load_sem = {0};
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load_sem.location = VERT_ATTRIB_EDGEFLAG;
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load_sem.num_slots = 1;
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nir_ssa_def *load =
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nir_load_input(&b, 1, 32, nir_imm_int(&b, 0),
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.base = shader->num_inputs++,
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.component = 0,
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.dest_type = nir_type_float32,
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.io_semantics = load_sem);
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/* Store an edge flag. */
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nir_io_semantics semantics = {0};
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semantics.location = VARYING_SLOT_EDGE;
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semantics.num_slots = 1;
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nir_store_output(&b, load, nir_imm_int(&b, 0),
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.base = shader->num_outputs++,
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.component = 0,
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.io_semantics = semantics,
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.src_type = nir_type_float32,
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.write_mask = 0x1);
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nir_metadata_preserve(impl, nir_metadata_block_index |
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nir_metadata_dominance);
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return;
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}
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in = nir_variable_create(shader, nir_var_shader_in,
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glsl_vec4_type(), "edgeflag_in");
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in->data.location = VERT_ATTRIB_EDGEFLAG;
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in->data.driver_location = shader->num_inputs++;
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shader->info.inputs_read |= VERT_BIT_EDGEFLAG;
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out = nir_variable_create(shader, nir_var_shader_out,
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glsl_vec4_type(), "edgeflag_out");
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out->data.location = VARYING_SLOT_EDGE;
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shader->info.outputs_written |= VARYING_BIT_EDGE;
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def = nir_load_var(&b, in);
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nir_store_var(&b, out, def, 0xf);
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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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void nir_lower_passthrough_edgeflags(nir_shader *shader)
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{
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assert(shader->info.stage == MESA_SHADER_VERTEX);
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shader->info.vs.needs_edge_flag = true;
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lower_impl(nir_shader_get_entrypoint(shader));
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}
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