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 /*
25 * This lower pass lowers load_interpolated_input for various interpolation
26 * modes (as configured via nir_lower_interpolation_options bitmask) into
27 * load_attribute_deltas plus alu instructions:
28 *
29 * vec3 ad = load_attribute_deltas(varying_slot)
30 * float result = ad.x + ad.y * j + ad.z * i
31 *
32 */
33
34 #include "nir.h"
35 #include "nir_builder.h"
36
37 static bool
nir_lower_interpolation_block(nir_block * block,nir_builder * b,nir_lower_interpolation_options options)38 nir_lower_interpolation_block(nir_block *block, nir_builder *b,
39 nir_lower_interpolation_options options)
40 {
41 bool progress = false;
42
43 nir_foreach_instr_safe(instr, block) {
44 if (instr->type != nir_instr_type_intrinsic)
45 continue;
46
47 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
48
49 if (intr->intrinsic != nir_intrinsic_load_interpolated_input)
50 continue;
51
52 assert(intr->dest.is_ssa);
53 assert(intr->src[0].is_ssa);
54 assert(intr->src[1].is_ssa);
55
56 nir_intrinsic_instr *bary_intrinsic =
57 nir_instr_as_intrinsic(intr->src[0].ssa->parent_instr);
58
59 /* Leave VARYING_SLOT_POS alone */
60 if (nir_intrinsic_base(intr) == VARYING_SLOT_POS)
61 continue;
62
63 const enum glsl_interp_mode interp_mode =
64 nir_intrinsic_interp_mode(bary_intrinsic);
65
66 /* We need actual interpolation modes by the time we get here */
67 assert(interp_mode != INTERP_MODE_NONE);
68
69 /* Only lower for inputs that need interpolation */
70 if (interp_mode != INTERP_MODE_SMOOTH &&
71 interp_mode != INTERP_MODE_NOPERSPECTIVE)
72 continue;
73
74 nir_intrinsic_op op = bary_intrinsic->intrinsic;
75
76 switch (op) {
77 case nir_intrinsic_load_barycentric_at_sample:
78 if (options & nir_lower_interpolation_at_sample)
79 break;
80 continue;
81 case nir_intrinsic_load_barycentric_at_offset:
82 if (options & nir_lower_interpolation_at_offset)
83 break;
84 continue;
85 case nir_intrinsic_load_barycentric_centroid:
86 if (options & nir_lower_interpolation_centroid)
87 break;
88 continue;
89 case nir_intrinsic_load_barycentric_pixel:
90 if (options & nir_lower_interpolation_pixel)
91 break;
92 continue;
93 case nir_intrinsic_load_barycentric_sample:
94 if (options & nir_lower_interpolation_sample)
95 break;
96 continue;
97 default:
98 continue;
99 }
100
101 b->cursor = nir_before_instr(instr);
102
103 nir_ssa_def *comps[NIR_MAX_VEC_COMPONENTS];
104 for (int i = 0; i < intr->num_components; i++) {
105 nir_ssa_def *iid =
106 nir_load_fs_input_interp_deltas(b, 32, intr->src[1].ssa,
107 .base = nir_intrinsic_base(intr),
108 .component = (nir_intrinsic_component(intr) + i),
109 .io_semantics = nir_intrinsic_io_semantics(intr));
110
111 nir_ssa_def *bary = intr->src[0].ssa;
112 nir_ssa_def *val;
113
114 val = nir_ffma(b, nir_channel(b, bary, 1),
115 nir_channel(b, iid, 1),
116 nir_channel(b, iid, 0));
117 val = nir_ffma(b, nir_channel(b, bary, 0),
118 nir_channel(b, iid, 2),
119 val);
120
121 comps[i] = val;
122 }
123 nir_ssa_def *vec = nir_vec(b, comps, intr->num_components);
124 nir_ssa_def_rewrite_uses(&intr->dest.ssa, vec);
125
126 progress = true;
127 }
128
129 return progress;
130 }
131
132 static bool
nir_lower_interpolation_impl(nir_function_impl * impl,nir_lower_interpolation_options options)133 nir_lower_interpolation_impl(nir_function_impl *impl,
134 nir_lower_interpolation_options options)
135 {
136 bool progress = false;
137 nir_builder builder;
138 nir_builder_init(&builder, impl);
139
140 nir_foreach_block(block, impl) {
141 progress |= nir_lower_interpolation_block(block, &builder, options);
142 }
143
144 nir_metadata_preserve(impl, nir_metadata_block_index |
145 nir_metadata_dominance);
146 return progress;
147 }
148
149 bool
nir_lower_interpolation(nir_shader * shader,nir_lower_interpolation_options options)150 nir_lower_interpolation(nir_shader *shader, nir_lower_interpolation_options options)
151 {
152 bool progress = false;
153
154 nir_foreach_function(function, shader) {
155 if (function->impl)
156 progress |= nir_lower_interpolation_impl(function->impl, options);
157 }
158
159 return progress;
160 }
161