1/*
2 * Copyright © 2021 Intel Corporation
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 "nir.h"
25#include "nir_builder.h"
26
27#include "util/set.h"
28#include "util/macros.h"
29
30/** @file nir_opt_ray_queries.c
31 *
32 * Remove ray queries that the shader is not using the result of.
33 */
34
35static void
36mark_query_read(struct set *queries,
37                nir_intrinsic_instr *intrin)
38{
39   nir_ssa_def *rq_def = intrin->src[0].ssa;
40
41   nir_variable *query;
42   if (rq_def->parent_instr->type == nir_instr_type_intrinsic) {
43      nir_intrinsic_instr *load_deref =
44         nir_instr_as_intrinsic(rq_def->parent_instr);
45      assert(load_deref->intrinsic == nir_intrinsic_load_deref);
46
47      query = nir_intrinsic_get_var(load_deref, 0);
48   } else if (rq_def->parent_instr->type == nir_instr_type_deref) {
49      query = nir_deref_instr_get_variable(
50         nir_instr_as_deref(rq_def->parent_instr));
51   } else {
52      return;
53   }
54   assert(query);
55
56   _mesa_set_add(queries, query);
57}
58
59static void
60nir_find_ray_queries_read(struct set *queries,
61                          nir_shader *shader)
62{
63   nir_foreach_function(function, shader) {
64      nir_function_impl *impl = function->impl;
65
66      if (!impl)
67         continue;
68
69      nir_foreach_block(block, impl) {
70         nir_foreach_instr(instr, block) {
71            if (instr->type != nir_instr_type_intrinsic)
72               continue;
73
74            nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
75            switch (intrin->intrinsic) {
76            case nir_intrinsic_rq_proceed:
77               if (list_length(&intrin->dest.ssa.uses) > 0 ||
78                   list_length(&intrin->dest.ssa.if_uses) > 0)
79                  mark_query_read(queries, intrin);
80               break;
81            case nir_intrinsic_rq_load:
82               mark_query_read(queries, intrin);
83               break;
84            default:
85               break;
86            }
87         }
88      }
89   }
90}
91
92static bool
93nir_replace_unread_queries_instr(nir_builder *b, nir_instr *instr, void *data)
94{
95   struct set *queries = data;
96
97   if (instr->type != nir_instr_type_intrinsic)
98      return false;
99
100   nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
101   switch (intrin->intrinsic) {
102   case nir_intrinsic_rq_initialize:
103   case nir_intrinsic_rq_terminate:
104   case nir_intrinsic_rq_generate_intersection:
105   case nir_intrinsic_rq_confirm_intersection:
106      break;
107   case nir_intrinsic_rq_proceed:
108      break;
109   default:
110      return false;
111   }
112
113   nir_variable *query = nir_intrinsic_get_var(intrin, 0);
114   assert(query);
115
116   struct set_entry *entry = _mesa_set_search(queries, query);
117   if (entry)
118      return false;
119
120   if (intrin->intrinsic == nir_intrinsic_rq_load) {
121      assert(list_is_empty(&intrin->dest.ssa.uses));
122      assert(list_is_empty(&intrin->dest.ssa.if_uses));
123   }
124
125   nir_instr_remove(instr);
126
127   return true;
128}
129
130bool
131nir_opt_ray_queries(nir_shader *shader)
132{
133   struct set *read_queries = _mesa_pointer_set_create(NULL);
134   nir_find_ray_queries_read(read_queries, shader);
135
136   bool progress =
137      nir_shader_instructions_pass(shader,
138                                   nir_replace_unread_queries_instr,
139                                   nir_metadata_block_index |
140                                   nir_metadata_dominance,
141                                   read_queries);
142
143   /* Update the number of queries if some have been removed. */
144   if (progress) {
145      nir_remove_dead_derefs(shader);
146      nir_remove_dead_variables(shader,
147                                nir_var_shader_temp | nir_var_function_temp,
148                                NULL);
149      nir_shader_gather_info(shader, nir_shader_get_entrypoint(shader));
150   }
151
152   _mesa_set_destroy(read_queries, NULL);
153
154   return progress;
155}
156