1 /*
2 * Copyright © 2019 Google, Inc.
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
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24 #include "ir3_nir.h"
25 #include "compiler/nir/nir_builder.h"
26
27 /**
28 * This pass lowers load_barycentric_at_sample to load_sample_pos_from_id
29 * plus load_barycentric_at_offset.
30 *
31 * It also lowers load_sample_pos to load_sample_pos_from_id, mostly because
32 * that needs to happen at the same early stage (before wpos_ytransform)
33 */
34
35 static nir_ssa_def *
load_sample_pos(nir_builder * b,nir_ssa_def * samp_id)36 load_sample_pos(nir_builder *b, nir_ssa_def *samp_id)
37 {
38 nir_intrinsic_instr *load_sp =
39 nir_intrinsic_instr_create(b->shader,
40 nir_intrinsic_load_sample_pos_from_id);
41 load_sp->src[0] = nir_src_for_ssa(samp_id);
42 nir_ssa_dest_init(&load_sp->instr, &load_sp->dest, 2, 32, NULL);
43 nir_builder_instr_insert(b, &load_sp->instr);
44
45 return &load_sp->dest.ssa;
46 }
47
48 static nir_ssa_def *
lower_load_barycentric_at_sample(nir_builder * b,nir_intrinsic_instr * intr)49 lower_load_barycentric_at_sample(nir_builder *b, nir_intrinsic_instr *intr)
50 {
51 nir_ssa_def *pos = load_sample_pos(b, intr->src[0].ssa);
52
53 nir_intrinsic_instr *load_bary_at_offset =
54 nir_intrinsic_instr_create(b->shader,
55 nir_intrinsic_load_barycentric_at_offset);
56 load_bary_at_offset->src[0] = nir_src_for_ssa(pos);
57 nir_ssa_dest_init(&load_bary_at_offset->instr,
58 &load_bary_at_offset->dest, 2, 32, NULL);
59 nir_builder_instr_insert(b, &load_bary_at_offset->instr);
60
61 return &load_bary_at_offset->dest.ssa;
62 }
63
64 static nir_ssa_def *
lower_load_sample_pos(nir_builder * b,nir_intrinsic_instr * intr)65 lower_load_sample_pos(nir_builder *b, nir_intrinsic_instr *intr)
66 {
67 nir_ssa_def *pos = load_sample_pos(b, nir_load_sample_id(b));
68
69 /* Note that gl_SamplePosition is offset by +vec2(0.5, 0.5) vs the
70 * offset passed to interpolateAtOffset(). See
71 * dEQP-GLES31.functional.shaders.multisample_interpolation.interpolate_at_offset.at_sample_position.default_framebuffer
72 * for example.
73 */
74 nir_ssa_def *half = nir_imm_float(b, 0.5);
75 return nir_fadd(b, pos, nir_vec2(b, half, half));
76 }
77
78 static nir_ssa_def *
ir3_nir_lower_load_barycentric_at_sample_instr(nir_builder * b,nir_instr * instr,void * data)79 ir3_nir_lower_load_barycentric_at_sample_instr(nir_builder *b,
80 nir_instr *instr, void *data)
81 {
82 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
83
84 if (intr->intrinsic == nir_intrinsic_load_sample_pos)
85 return lower_load_sample_pos(b, intr);
86 else
87 return lower_load_barycentric_at_sample(b, intr);
88 }
89
90 static bool
ir3_nir_lower_load_barycentric_at_sample_filter(const nir_instr * instr,const void * data)91 ir3_nir_lower_load_barycentric_at_sample_filter(const nir_instr *instr,
92 const void *data)
93 {
94 if (instr->type != nir_instr_type_intrinsic)
95 return false;
96 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
97 return (intr->intrinsic == nir_intrinsic_load_barycentric_at_sample ||
98 intr->intrinsic == nir_intrinsic_load_sample_pos);
99 }
100
101 bool
ir3_nir_lower_load_barycentric_at_sample(nir_shader * shader)102 ir3_nir_lower_load_barycentric_at_sample(nir_shader *shader)
103 {
104 debug_assert(shader->info.stage == MESA_SHADER_FRAGMENT);
105
106 return nir_shader_lower_instructions(shader,
107 ir3_nir_lower_load_barycentric_at_sample_filter,
108 ir3_nir_lower_load_barycentric_at_sample_instr,
109 NULL);
110 }
111