1 /*
2 * Copyright © 2019 Google, Inc.
3 * SPDX-License-Identifier: MIT
4 */
5
6 #include "compiler/nir/nir_builder.h"
7 #include "ir3_nir.h"
8
9 /**
10 * This pass lowers load_barycentric_at_sample to load_sample_pos_from_id
11 * plus load_barycentric_at_offset.
12 *
13 * It also lowers load_sample_pos to load_sample_pos_from_id, mostly because
14 * that needs to happen at the same early stage (before wpos_ytransform)
15 */
16
17 static nir_def *
load_sample_pos(nir_builder * b,nir_def * samp_id)18 load_sample_pos(nir_builder *b, nir_def *samp_id)
19 {
20 return nir_load_sample_pos_from_id(b, 32, samp_id);
21 }
22
23 static nir_def *
lower_load_barycentric_at_sample(nir_builder * b,nir_intrinsic_instr * intr)24 lower_load_barycentric_at_sample(nir_builder *b, nir_intrinsic_instr *intr)
25 {
26 nir_def *pos = load_sample_pos(b, intr->src[0].ssa);
27
28 return nir_load_barycentric_at_offset(b, 32, pos, .interp_mode = nir_intrinsic_interp_mode(intr));
29 }
30
31 static nir_def *
lower_load_sample_pos(nir_builder * b,nir_intrinsic_instr * intr)32 lower_load_sample_pos(nir_builder *b, nir_intrinsic_instr *intr)
33 {
34 nir_def *pos = load_sample_pos(b, nir_load_sample_id(b));
35
36 /* Note that gl_SamplePosition is offset by +vec2(0.5, 0.5) vs the
37 * offset passed to interpolateAtOffset(). See
38 * dEQP-GLES31.functional.shaders.multisample_interpolation.interpolate_at_offset.at_sample_position.default_framebuffer
39 * for example.
40 */
41 nir_def *half = nir_imm_float(b, 0.5);
42 return nir_fadd(b, pos, nir_vec2(b, half, half));
43 }
44
45 static nir_def *
ir3_nir_lower_load_barycentric_at_sample_instr(nir_builder * b,nir_instr * instr,void * data)46 ir3_nir_lower_load_barycentric_at_sample_instr(nir_builder *b, nir_instr *instr,
47 void *data)
48 {
49 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
50
51 if (intr->intrinsic == nir_intrinsic_load_sample_pos)
52 return lower_load_sample_pos(b, intr);
53 else
54 return lower_load_barycentric_at_sample(b, intr);
55 }
56
57 static bool
ir3_nir_lower_load_barycentric_at_sample_filter(const nir_instr * instr,const void * data)58 ir3_nir_lower_load_barycentric_at_sample_filter(const nir_instr *instr,
59 const void *data)
60 {
61 if (instr->type != nir_instr_type_intrinsic)
62 return false;
63 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
64 return (intr->intrinsic == nir_intrinsic_load_barycentric_at_sample ||
65 intr->intrinsic == nir_intrinsic_load_sample_pos);
66 }
67
68 bool
ir3_nir_lower_load_barycentric_at_sample(nir_shader * shader)69 ir3_nir_lower_load_barycentric_at_sample(nir_shader *shader)
70 {
71 assert(shader->info.stage == MESA_SHADER_FRAGMENT);
72
73 return nir_shader_lower_instructions(
74 shader, ir3_nir_lower_load_barycentric_at_sample_filter,
75 ir3_nir_lower_load_barycentric_at_sample_instr, NULL);
76 }
77