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
27static void
28lower_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.  This code is also called by
39    * i965 which calls it before any input locations are assigned.
40    */
41   assert(shader->num_inputs == 0 ||
42          shader->num_inputs == util_bitcount64(shader->info.inputs_read));
43
44   /* Lowered IO only uses intrinsics. It doesn't use variables. */
45   if (shader->info.io_lowered) {
46      assert(shader->num_outputs ==
47             util_bitcount64(shader->info.outputs_written));
48
49      /* Load an edge flag. */
50      nir_io_semantics load_sem = {0};
51      load_sem.location = VERT_ATTRIB_EDGEFLAG;
52      load_sem.num_slots = 1;
53
54      nir_ssa_def *load =
55         nir_load_input(&b, 1, 32, nir_imm_int(&b, 0),
56                        .base = shader->num_inputs++,
57                        .component = 0,
58                        .dest_type = nir_type_float32,
59                        .io_semantics = load_sem);
60
61      /* Store an edge flag. */
62      nir_io_semantics semantics = {0};
63      semantics.location = VARYING_SLOT_EDGE;
64      semantics.num_slots = 1;
65
66      nir_store_output(&b, load, nir_imm_int(&b, 0),
67                       .base = shader->num_outputs++,
68                       .component = 0,
69                       .io_semantics = semantics,
70                       .src_type = nir_type_float32,
71                       .write_mask = 0x1);
72
73      nir_metadata_preserve(impl, nir_metadata_block_index |
74                                  nir_metadata_dominance);
75      return;
76   }
77
78   in  = nir_variable_create(shader, nir_var_shader_in,
79                             glsl_vec4_type(), "edgeflag_in");
80   in->data.location = VERT_ATTRIB_EDGEFLAG;
81
82   in->data.driver_location = shader->num_inputs++;
83   shader->info.inputs_read |= VERT_BIT_EDGEFLAG;
84
85   out = nir_variable_create(shader, nir_var_shader_out,
86                             glsl_vec4_type(), "edgeflag_out");
87   out->data.location = VARYING_SLOT_EDGE;
88   shader->info.outputs_written |= VARYING_BIT_EDGE;
89
90   def = nir_load_var(&b, in);
91   nir_store_var(&b, out, def, 0xf);
92
93   nir_metadata_preserve(impl, nir_metadata_block_index |
94                               nir_metadata_dominance);
95}
96
97void nir_lower_passthrough_edgeflags(nir_shader *shader)
98{
99   assert(shader->info.stage == MESA_SHADER_VERTEX);
100
101   shader->info.vs.needs_edge_flag = true;
102
103   lower_impl(nir_shader_get_entrypoint(shader));
104}
105