1 /*
2 * Copyright © 2016 Red Hat.
3 * Copyright © 2016 Bas Nieuwenhuizen
4 * Copyright © 2023 Valve Corporation
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the next
14 * paragraph) shall be included in all copies or substantial portions of the
15 * Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
23 * IN THE SOFTWARE.
24 */
25
26 #include "nir.h"
27 #include "nir_builder.h"
28 #include "radv_nir.h"
29
30 static nir_variable *
find_layer_in_var(nir_shader * nir)31 find_layer_in_var(nir_shader *nir)
32 {
33 nir_variable *var = nir_find_variable_with_location(nir, nir_var_shader_in, VARYING_SLOT_LAYER);
34 if (var != NULL)
35 return var;
36
37 var = nir_variable_create(nir, nir_var_shader_in, glsl_int_type(), "layer id");
38 var->data.location = VARYING_SLOT_LAYER;
39 var->data.interpolation = INTERP_MODE_FLAT;
40 return var;
41 }
42
43 /**
44 * We use layered rendering to implement multiview, which means we need to map
45 * view_index to gl_Layer. The code generates a load from the layer_id sysval,
46 * but since we don't have a way to get at this information from the fragment
47 * shader, we also need to lower this to the gl_Layer varying. This pass
48 * lowers both to a varying load from the LAYER slot, before lowering io, so
49 * that nir_assign_var_locations() will give the LAYER varying the correct
50 * driver_location.
51 */
52 bool
radv_nir_lower_view_index(nir_shader * nir,bool per_primitive)53 radv_nir_lower_view_index(nir_shader *nir, bool per_primitive)
54 {
55 bool progress = false;
56 nir_function_impl *entry = nir_shader_get_entrypoint(nir);
57 nir_builder b = nir_builder_create(entry);
58
59 nir_variable *layer = NULL;
60 nir_foreach_block (block, entry) {
61 nir_foreach_instr_safe (instr, block) {
62 if (instr->type != nir_instr_type_intrinsic)
63 continue;
64
65 nir_intrinsic_instr *load = nir_instr_as_intrinsic(instr);
66 if (load->intrinsic != nir_intrinsic_load_view_index)
67 continue;
68
69 if (!layer)
70 layer = find_layer_in_var(nir);
71
72 layer->data.per_primitive = per_primitive;
73 b.cursor = nir_before_instr(instr);
74 nir_def *def = nir_load_var(&b, layer);
75 nir_def_rewrite_uses(&load->def, def);
76
77 /* Update inputs_read to reflect that the pass added a new input. */
78 nir->info.inputs_read |= VARYING_BIT_LAYER;
79 if (per_primitive)
80 nir->info.per_primitive_inputs |= VARYING_BIT_LAYER;
81
82 nir_instr_remove(instr);
83 progress = true;
84 }
85 }
86
87 if (progress)
88 nir_metadata_preserve(entry, nir_metadata_block_index | nir_metadata_dominance);
89 else
90 nir_metadata_preserve(entry, nir_metadata_all);
91
92 return progress;
93 }