src/compiler/nir/nir_lower_passthrough_edgeflags.c

   1 /*
   2  * Copyright © 2015 Red Hat
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #include "nir.h"
  25 #include "nir_builder.h"
  26
  27 static void
  28 lower_impl(nir_function_impl *impl)
  29 {
  30    nir_shader *shader = impl->function->shader;
  31    nir_builder b;
  32    nir_variable *in, *out;
  33    nir_ssa_def *def;
  34
  35    nir_builder_init(&b, impl);
  36    b.cursor = nir_before_cf_list(&impl->body);
  37
  38    /* The edge flag is the last input in st/mesa. */
  39    assert(shader->num_inputs == util_bitcount64(shader->info.inputs_read));
  40    assert(shader->num_outputs == util_bitcount64(shader->info.outputs_written));
  41
  42    /* Lowered IO only uses intrinsics. It doesn't use variables. */
  43    if (shader->info.io_lowered) {
  44       /* Load an edge flag. */
  45       nir_intrinsic_instr *load =
  46          nir_intrinsic_instr_create(shader, nir_intrinsic_load_input);
  47       load->num_components = 1;
  48       load->src[0] = nir_src_for_ssa(nir_imm_int(&b, 0));
  49       nir_ssa_dest_init(&load->instr, &load->dest,
  50                         load->num_components, 32, NULL);
  51
  52       nir_intrinsic_set_base(load, shader->num_inputs++);
  53       nir_intrinsic_set_component(load, 0);
  54       nir_intrinsic_set_type(load, nir_type_float32);
  55
  56       nir_io_semantics load_sem = {0};
  57       load_sem.location = VERT_ATTRIB_EDGEFLAG;
  58       load_sem.num_slots = 1;
  59       nir_intrinsic_set_io_semantics(load, load_sem);
  60       nir_builder_instr_insert(&b, &load->instr);
  61
  62       /* Store an edge flag. */
  63       nir_intrinsic_instr *store =
  64          nir_intrinsic_instr_create(shader, nir_intrinsic_store_output);
  65       store->num_components = 1;
  66       store->src[0] = nir_src_for_ssa(&load->dest.ssa);
  67       store->src[1] = nir_src_for_ssa(nir_imm_int(&b, 0));
  68
  69       nir_intrinsic_set_base(store, shader->num_outputs++);
  70       nir_intrinsic_set_component(store, 0);
  71       nir_intrinsic_set_type(store, nir_type_float32);
  72       nir_intrinsic_set_write_mask(store, 0x1);
  73
  74       nir_io_semantics semantics = {0};
  75       semantics.location = VARYING_SLOT_EDGE;
  76       semantics.num_slots = 1;
  77       nir_intrinsic_set_io_semantics(store, semantics);
  78       nir_builder_instr_insert(&b, &store->instr);
  79
  80       nir_metadata_preserve(impl, nir_metadata_block_index |
  81                                   nir_metadata_dominance);
  82       return;
  83    }
  84
  85    in  = nir_variable_create(shader, nir_var_shader_in,
  86                              glsl_vec4_type(), "edgeflag_in");
  87    in->data.location = VERT_ATTRIB_EDGEFLAG;
  88
  89    in->data.driver_location = shader->num_inputs++;
  90    shader->info.inputs_read |= BITFIELD64_BIT(VERT_ATTRIB_EDGEFLAG);
  91
  92    out = nir_variable_create(shader, nir_var_shader_out,
  93                              glsl_vec4_type(), "edgeflag_out");
  94    out->data.location = VARYING_SLOT_EDGE;
  95
  96    def = nir_load_var(&b, in);
  97    nir_store_var(&b, out, def, 0xf);
  98
  99    nir_metadata_preserve(impl, nir_metadata_block_index |
 100                                nir_metadata_dominance);
 101 }
 102
 103 void nir_lower_passthrough_edgeflags(nir_shader *shader)
 104 {
 105    lower_impl(nir_shader_get_entrypoint(shader));
 106 }