1 /*
2 * Copyright © 2014 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 * Authors:
24 * Connor Abbott (cwabbott0@gmail.com)
25 *
26 */
27
28 #include "nir.h"
29 #include <main/imports.h>
30
31 /**
32 * SSA-based copy propagation
33 */
34
is_move(nir_alu_instr * instr)35 static bool is_move(nir_alu_instr *instr)
36 {
37 if (instr->op != nir_op_fmov &&
38 instr->op != nir_op_imov)
39 return false;
40
41 if (instr->dest.saturate)
42 return false;
43
44 /* we handle modifiers in a separate pass */
45
46 if (instr->src[0].abs || instr->src[0].negate)
47 return false;
48
49 if (!instr->src[0].src.is_ssa)
50 return false;
51
52 return true;
53
54 }
55
is_vec(nir_alu_instr * instr)56 static bool is_vec(nir_alu_instr *instr)
57 {
58 for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
59 if (!instr->src[i].src.is_ssa)
60 return false;
61
62 /* we handle modifiers in a separate pass */
63 if (instr->src[i].abs || instr->src[i].negate)
64 return false;
65 }
66
67 return instr->op == nir_op_vec2 ||
68 instr->op == nir_op_vec3 ||
69 instr->op == nir_op_vec4;
70 }
71
72 static bool
is_swizzleless_move(nir_alu_instr * instr)73 is_swizzleless_move(nir_alu_instr *instr)
74 {
75 if (is_move(instr)) {
76 for (unsigned i = 0; i < 4; i++) {
77 if (!((instr->dest.write_mask >> i) & 1))
78 break;
79 if (instr->src[0].swizzle[i] != i)
80 return false;
81 }
82 return true;
83 } else if (is_vec(instr)) {
84 nir_ssa_def *def = NULL;
85 for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
86 if (instr->src[i].swizzle[0] != i)
87 return false;
88
89 if (def == NULL) {
90 def = instr->src[i].src.ssa;
91 } else if (instr->src[i].src.ssa != def) {
92 return false;
93 }
94 }
95 return true;
96 } else {
97 return false;
98 }
99 }
100
101 static bool
copy_prop_src(nir_src * src,nir_instr * parent_instr,nir_if * parent_if)102 copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if)
103 {
104 if (!src->is_ssa) {
105 if (src->reg.indirect)
106 return copy_prop_src(src->reg.indirect, parent_instr, parent_if);
107 return false;
108 }
109
110 nir_instr *src_instr = src->ssa->parent_instr;
111 if (src_instr->type != nir_instr_type_alu)
112 return false;
113
114 nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
115 if (!is_swizzleless_move(alu_instr))
116 return false;
117
118 /* Don't let copy propagation land us with a phi that has more
119 * components in its source than it has in its destination. That badly
120 * messes up out-of-ssa.
121 */
122 if (parent_instr && parent_instr->type == nir_instr_type_phi) {
123 nir_phi_instr *phi = nir_instr_as_phi(parent_instr);
124 assert(phi->dest.is_ssa);
125 if (phi->dest.ssa.num_components !=
126 alu_instr->src[0].src.ssa->num_components)
127 return false;
128 }
129
130 if (parent_instr) {
131 nir_instr_rewrite_src(parent_instr, src,
132 nir_src_for_ssa(alu_instr->src[0].src.ssa));
133 } else {
134 assert(src == &parent_if->condition);
135 nir_if_rewrite_condition(parent_if,
136 nir_src_for_ssa(alu_instr->src[0].src.ssa));
137 }
138
139 return true;
140 }
141
142 static bool
copy_prop_alu_src(nir_alu_instr * parent_alu_instr,unsigned index)143 copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
144 {
145 nir_alu_src *src = &parent_alu_instr->src[index];
146 if (!src->src.is_ssa) {
147 if (src->src.reg.indirect)
148 return copy_prop_src(src->src.reg.indirect, &parent_alu_instr->instr,
149 NULL);
150 return false;
151 }
152
153 nir_instr *src_instr = src->src.ssa->parent_instr;
154 if (src_instr->type != nir_instr_type_alu)
155 return false;
156
157 nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
158 if (!is_move(alu_instr) && !is_vec(alu_instr))
159 return false;
160
161 nir_ssa_def *def;
162 unsigned new_swizzle[4] = {0, 0, 0, 0};
163
164 if (alu_instr->op == nir_op_fmov ||
165 alu_instr->op == nir_op_imov) {
166 for (unsigned i = 0; i < 4; i++)
167 new_swizzle[i] = alu_instr->src[0].swizzle[src->swizzle[i]];
168 def = alu_instr->src[0].src.ssa;
169 } else {
170 def = NULL;
171
172 for (unsigned i = 0; i < 4; i++) {
173 if (!nir_alu_instr_channel_used(parent_alu_instr, index, i))
174 continue;
175
176 nir_ssa_def *new_def = alu_instr->src[src->swizzle[i]].src.ssa;
177 if (def == NULL)
178 def = new_def;
179 else {
180 if (def != new_def)
181 return false;
182 }
183 new_swizzle[i] = alu_instr->src[src->swizzle[i]].swizzle[0];
184 }
185 }
186
187 for (unsigned i = 0; i < 4; i++)
188 src->swizzle[i] = new_swizzle[i];
189
190 nir_instr_rewrite_src(&parent_alu_instr->instr, &src->src,
191 nir_src_for_ssa(def));
192
193 return true;
194 }
195
196 typedef struct {
197 nir_instr *parent_instr;
198 bool progress;
199 } copy_prop_state;
200
201 static bool
copy_prop_src_cb(nir_src * src,void * _state)202 copy_prop_src_cb(nir_src *src, void *_state)
203 {
204 copy_prop_state *state = (copy_prop_state *) _state;
205 while (copy_prop_src(src, state->parent_instr, NULL))
206 state->progress = true;
207
208 return true;
209 }
210
211 static bool
copy_prop_instr(nir_instr * instr)212 copy_prop_instr(nir_instr *instr)
213 {
214 if (instr->type == nir_instr_type_alu) {
215 nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
216 bool progress = false;
217
218 for (unsigned i = 0; i < nir_op_infos[alu_instr->op].num_inputs; i++)
219 while (copy_prop_alu_src(alu_instr, i))
220 progress = true;
221
222 if (!alu_instr->dest.dest.is_ssa && alu_instr->dest.dest.reg.indirect)
223 while (copy_prop_src(alu_instr->dest.dest.reg.indirect, instr, NULL))
224 progress = true;
225
226 return progress;
227 }
228
229 copy_prop_state state;
230 state.parent_instr = instr;
231 state.progress = false;
232 nir_foreach_src(instr, copy_prop_src_cb, &state);
233
234 return state.progress;
235 }
236
237 static bool
copy_prop_if(nir_if * if_stmt)238 copy_prop_if(nir_if *if_stmt)
239 {
240 return copy_prop_src(&if_stmt->condition, NULL, if_stmt);
241 }
242
243 static bool
nir_copy_prop_impl(nir_function_impl * impl)244 nir_copy_prop_impl(nir_function_impl *impl)
245 {
246 bool progress = false;
247
248 nir_foreach_block(block, impl) {
249 nir_foreach_instr(instr, block) {
250 if (copy_prop_instr(instr))
251 progress = true;
252 }
253
254 nir_if *if_stmt = nir_block_get_following_if(block);
255 if (if_stmt && copy_prop_if(if_stmt))
256 progress = true;
257 }
258
259 if (progress) {
260 nir_metadata_preserve(impl, nir_metadata_block_index |
261 nir_metadata_dominance);
262 }
263
264 return progress;
265 }
266
267 bool
nir_copy_prop(nir_shader * shader)268 nir_copy_prop(nir_shader *shader)
269 {
270 bool progress = false;
271
272 nir_foreach_function(function, shader) {
273 if (function->impl && nir_copy_prop_impl(function->impl))
274 progress = true;
275 }
276
277 return progress;
278 }
279