1 /*
2 * Copyright © 2016 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
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24 #include "nir.h"
25
26 static void
add_src(nir_src * src,struct set * invariants)27 add_src(nir_src *src, struct set *invariants)
28 {
29 if (src->is_ssa) {
30 _mesa_set_add(invariants, src->ssa);
31 } else {
32 _mesa_set_add(invariants, src->reg.reg);
33 }
34 }
35
36 static bool
add_src_cb(nir_src * src,void * state)37 add_src_cb(nir_src *src, void *state)
38 {
39 add_src(src, state);
40 return true;
41 }
42
43 static bool
dest_is_invariant(nir_dest * dest,struct set * invariants)44 dest_is_invariant(nir_dest *dest, struct set *invariants)
45 {
46 if (dest->is_ssa) {
47 return _mesa_set_search(invariants, &dest->ssa);
48 } else {
49 return _mesa_set_search(invariants, dest->reg.reg);
50 }
51 }
52
53 static void
add_cf_node(nir_cf_node * cf,struct set * invariants)54 add_cf_node(nir_cf_node *cf, struct set *invariants)
55 {
56 if (cf->type == nir_cf_node_if) {
57 nir_if *if_stmt = nir_cf_node_as_if(cf);
58 add_src(&if_stmt->condition, invariants);
59 }
60
61 if (cf->parent)
62 add_cf_node(cf->parent, invariants);
63 }
64
65 static void
add_var(nir_variable * var,struct set * invariants)66 add_var(nir_variable *var, struct set *invariants)
67 {
68 _mesa_set_add(invariants, var);
69 }
70
71 static bool
var_is_invariant(nir_variable * var,struct set * invariants)72 var_is_invariant(nir_variable *var, struct set * invariants)
73 {
74 return var->data.invariant || _mesa_set_search(invariants, var);
75 }
76
77 static void
propagate_invariant_instr(nir_instr * instr,struct set * invariants)78 propagate_invariant_instr(nir_instr *instr, struct set *invariants)
79 {
80 switch (instr->type) {
81 case nir_instr_type_alu: {
82 nir_alu_instr *alu = nir_instr_as_alu(instr);
83 if (!dest_is_invariant(&alu->dest.dest, invariants))
84 break;
85
86 alu->exact = true;
87 nir_foreach_src(instr, add_src_cb, invariants);
88 break;
89 }
90
91 case nir_instr_type_tex: {
92 nir_tex_instr *tex = nir_instr_as_tex(instr);
93 if (dest_is_invariant(&tex->dest, invariants))
94 nir_foreach_src(instr, add_src_cb, invariants);
95 break;
96 }
97
98 case nir_instr_type_intrinsic: {
99 nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
100 switch (intrin->intrinsic) {
101 case nir_intrinsic_copy_var:
102 /* If the destination is invariant then so is the source */
103 if (var_is_invariant(intrin->variables[0]->var, invariants))
104 add_var(intrin->variables[1]->var, invariants);
105 break;
106
107 case nir_intrinsic_load_var:
108 if (dest_is_invariant(&intrin->dest, invariants))
109 add_var(intrin->variables[0]->var, invariants);
110 break;
111
112 case nir_intrinsic_store_var:
113 if (var_is_invariant(intrin->variables[0]->var, invariants))
114 add_src(&intrin->src[0], invariants);
115 break;
116
117 default:
118 /* Nothing to do */
119 break;
120 }
121 }
122
123 case nir_instr_type_jump:
124 case nir_instr_type_ssa_undef:
125 case nir_instr_type_load_const:
126 break; /* Nothing to do */
127
128 case nir_instr_type_phi: {
129 nir_phi_instr *phi = nir_instr_as_phi(instr);
130 if (!dest_is_invariant(&phi->dest, invariants))
131 break;
132
133 nir_foreach_phi_src(src, phi) {
134 add_src(&src->src, invariants);
135 add_cf_node(&src->pred->cf_node, invariants);
136 }
137 break;
138 }
139
140 case nir_instr_type_call:
141 unreachable("This pass must be run after function inlining");
142
143 case nir_instr_type_parallel_copy:
144 default:
145 unreachable("Cannot have this instruction type");
146 }
147 }
148
149 static bool
propagate_invariant_impl(nir_function_impl * impl,struct set * invariants)150 propagate_invariant_impl(nir_function_impl *impl, struct set *invariants)
151 {
152 bool progress = false;
153
154 while (true) {
155 uint32_t prev_entries = invariants->entries;
156
157 nir_foreach_block_reverse(block, impl) {
158 nir_foreach_instr_reverse(instr, block)
159 propagate_invariant_instr(instr, invariants);
160 }
161
162 /* Keep running until we make no more progress. */
163 if (invariants->entries > prev_entries) {
164 progress = true;
165 continue;
166 } else {
167 break;
168 }
169 }
170
171 if (progress) {
172 nir_metadata_preserve(impl, nir_metadata_block_index |
173 nir_metadata_dominance |
174 nir_metadata_live_ssa_defs);
175 }
176
177 return progress;
178 }
179
180 bool
nir_propagate_invariant(nir_shader * shader)181 nir_propagate_invariant(nir_shader *shader)
182 {
183 /* Hash set of invariant things */
184 struct set *invariants = _mesa_set_create(NULL, _mesa_hash_pointer,
185 _mesa_key_pointer_equal);
186
187 bool progress = false;
188 nir_foreach_function(function, shader) {
189 if (function->impl && propagate_invariant_impl(function->impl, invariants))
190 progress = true;
191 }
192
193 _mesa_set_destroy(invariants, NULL);
194
195 return progress;
196 }
197