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_instr(nir_builder * b,nir_instr * instr,void * cb_data)38 nir_lower_interpolation_instr(nir_builder *b, nir_instr *instr, void *cb_data)
39 {
40 nir_lower_interpolation_options options =
41 *(nir_lower_interpolation_options *)cb_data;
42
43 if (instr->type != nir_instr_type_intrinsic)
44 return false;
45
46 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
47
48 if (intr->intrinsic != nir_intrinsic_load_interpolated_input)
49 return false;
50
51 nir_intrinsic_instr *bary_intrinsic =
52 nir_instr_as_intrinsic(intr->src[0].ssa->parent_instr);
53
54 /* Leave VARYING_SLOT_POS alone */
55 if (nir_intrinsic_base(intr) == VARYING_SLOT_POS)
56 return false;
57
58 const enum glsl_interp_mode interp_mode =
59 nir_intrinsic_interp_mode(bary_intrinsic);
60
61 /* We need actual interpolation modes by the time we get here */
62 assert(interp_mode != INTERP_MODE_NONE);
63
64 /* Only lower for inputs that need interpolation */
65 if (interp_mode != INTERP_MODE_SMOOTH &&
66 interp_mode != INTERP_MODE_NOPERSPECTIVE)
67 return false;
68
69 nir_intrinsic_op op = bary_intrinsic->intrinsic;
70
71 switch (op) {
72 case nir_intrinsic_load_barycentric_at_sample:
73 if (options & nir_lower_interpolation_at_sample)
74 break;
75 return false;
76 case nir_intrinsic_load_barycentric_at_offset:
77 if (options & nir_lower_interpolation_at_offset)
78 break;
79 return false;
80 case nir_intrinsic_load_barycentric_centroid:
81 if (options & nir_lower_interpolation_centroid)
82 break;
83 return false;
84 case nir_intrinsic_load_barycentric_pixel:
85 if (options & nir_lower_interpolation_pixel)
86 break;
87 return false;
88 case nir_intrinsic_load_barycentric_sample:
89 if (options & nir_lower_interpolation_sample)
90 break;
91 return false;
92 default:
93 return false;
94 }
95
96 b->cursor = nir_before_instr(instr);
97
98 nir_def *comps[NIR_MAX_VEC_COMPONENTS];
99 for (int i = 0; i < intr->num_components; i++) {
100 nir_def *iid =
101 nir_load_fs_input_interp_deltas(b, 32, intr->src[1].ssa,
102 .base = nir_intrinsic_base(intr),
103 .component = (nir_intrinsic_component(intr) + i),
104 .io_semantics = nir_intrinsic_io_semantics(intr));
105
106 nir_def *bary = intr->src[0].ssa;
107 nir_def *val;
108
109 val = nir_ffma(b, nir_channel(b, bary, 1),
110 nir_channel(b, iid, 1),
111 nir_channel(b, iid, 0));
112 val = nir_ffma(b, nir_channel(b, bary, 0),
113 nir_channel(b, iid, 2),
114 val);
115
116 comps[i] = val;
117 }
118 nir_def *vec = nir_vec(b, comps, intr->num_components);
119 nir_def_rewrite_uses(&intr->def, vec);
120
121 return true;
122 }
123
124 bool
nir_lower_interpolation(nir_shader * shader,nir_lower_interpolation_options options)125 nir_lower_interpolation(nir_shader *shader, nir_lower_interpolation_options options)
126 {
127 return nir_shader_instructions_pass(shader, nir_lower_interpolation_instr,
128 nir_metadata_control_flow,
129 &options);
130 }
131