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1 /*
2  * Copyright © 2014 Broadcom
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  * @file vc4_opt_algebraic.c
26  *
27  * This is the optimization pass for miscellaneous changes to instructions
28  * where we can simplify the operation by some knowledge about the specific
29  * operations.
30  *
31  * Mostly this will be a matter of turning things into MOVs so that they can
32  * later be copy-propagated out.
33  */
34 
35 #include "vc4_qir.h"
36 #include "util/u_math.h"
37 
38 static bool debug;
39 
40 static void
dump_from(struct vc4_compile * c,struct qinst * inst)41 dump_from(struct vc4_compile *c, struct qinst *inst)
42 {
43         if (!debug)
44                 return;
45 
46         fprintf(stderr, "optimizing: ");
47         qir_dump_inst(c, inst);
48         fprintf(stderr, "\n");
49 }
50 
51 static void
dump_to(struct vc4_compile * c,struct qinst * inst)52 dump_to(struct vc4_compile *c, struct qinst *inst)
53 {
54         if (!debug)
55                 return;
56 
57         fprintf(stderr, "to: ");
58         qir_dump_inst(c, inst);
59         fprintf(stderr, "\n");
60 }
61 
62 static bool
is_constant_value(struct vc4_compile * c,struct qreg reg,uint32_t val)63 is_constant_value(struct vc4_compile *c, struct qreg reg,
64                   uint32_t val)
65 {
66         if (reg.file == QFILE_UNIF &&
67             !reg.pack &&
68             c->uniform_contents[reg.index] == QUNIFORM_CONSTANT &&
69             c->uniform_data[reg.index] == val) {
70                 return true;
71         }
72 
73         if (reg.file == QFILE_SMALL_IMM && reg.index == val)
74                 return true;
75 
76         return false;
77 }
78 
79 static bool
is_zero(struct vc4_compile * c,struct qreg reg)80 is_zero(struct vc4_compile *c, struct qreg reg)
81 {
82         reg = qir_follow_movs(c, reg);
83         return is_constant_value(c, reg, 0);
84 }
85 
86 static bool
is_1f(struct vc4_compile * c,struct qreg reg)87 is_1f(struct vc4_compile *c, struct qreg reg)
88 {
89         reg = qir_follow_movs(c, reg);
90         return is_constant_value(c, reg, fui(1.0));
91 }
92 
93 static void
replace_with_mov(struct vc4_compile * c,struct qinst * inst,struct qreg arg)94 replace_with_mov(struct vc4_compile *c, struct qinst *inst, struct qreg arg)
95 {
96         dump_from(c, inst);
97 
98         inst->src[0] = arg;
99         if (qir_has_implicit_tex_uniform(inst))
100                 inst->src[1] = inst->src[qir_get_tex_uniform_src(inst)];
101 
102         if (qir_is_mul(inst))
103                 inst->op = QOP_MMOV;
104         else if (qir_is_float_input(inst))
105                 inst->op = QOP_FMOV;
106         else
107                 inst->op = QOP_MOV;
108         dump_to(c, inst);
109 }
110 
111 static bool
replace_x_0_with_x(struct vc4_compile * c,struct qinst * inst,int arg)112 replace_x_0_with_x(struct vc4_compile *c,
113                  struct qinst *inst,
114                  int arg)
115 {
116         if (!is_zero(c, inst->src[arg]))
117                 return false;
118         replace_with_mov(c, inst, inst->src[1 - arg]);
119         return true;
120 }
121 
122 static bool
replace_x_0_with_0(struct vc4_compile * c,struct qinst * inst,int arg)123 replace_x_0_with_0(struct vc4_compile *c,
124                   struct qinst *inst,
125                   int arg)
126 {
127         if (!is_zero(c, inst->src[arg]))
128                 return false;
129         replace_with_mov(c, inst, inst->src[arg]);
130         return true;
131 }
132 
133 static bool
fmul_replace_one(struct vc4_compile * c,struct qinst * inst,int arg)134 fmul_replace_one(struct vc4_compile *c,
135                  struct qinst *inst,
136                  int arg)
137 {
138         if (!is_1f(c, inst->src[arg]))
139                 return false;
140         replace_with_mov(c, inst, inst->src[1 - arg]);
141         return true;
142 }
143 
144 bool
qir_opt_algebraic(struct vc4_compile * c)145 qir_opt_algebraic(struct vc4_compile *c)
146 {
147         bool progress = false;
148 
149         qir_for_each_inst_inorder(inst, c) {
150                 switch (inst->op) {
151                 case QOP_FMIN:
152                         if (is_1f(c, inst->src[1]) &&
153                             inst->src[0].pack >= QPU_UNPACK_8D_REP &&
154                             inst->src[0].pack <= QPU_UNPACK_8D) {
155                                 replace_with_mov(c, inst, inst->src[0]);
156                                 progress = true;
157                         }
158                         break;
159 
160                 case QOP_FMAX:
161                         if (is_zero(c, inst->src[1]) &&
162                             inst->src[0].pack >= QPU_UNPACK_8D_REP &&
163                             inst->src[0].pack <= QPU_UNPACK_8D) {
164                                 replace_with_mov(c, inst, inst->src[0]);
165                                 progress = true;
166                         }
167                         break;
168 
169                 case QOP_FSUB:
170                 case QOP_SUB:
171                         if (is_zero(c, inst->src[1])) {
172                                 replace_with_mov(c, inst, inst->src[0]);
173                                 progress = true;
174                         }
175                         break;
176 
177                 case QOP_ADD:
178                         /* Kernel validation requires that we use an actual
179                          * add instruction.
180                          */
181                         if (inst->dst.file != QFILE_TEX_S_DIRECT &&
182                             (replace_x_0_with_x(c, inst, 0) ||
183                              replace_x_0_with_x(c, inst, 1))) {
184                                 progress = true;
185                                 break;
186                         }
187                         break;
188 
189                 case QOP_FADD:
190                         if (replace_x_0_with_x(c, inst, 0) ||
191                             replace_x_0_with_x(c, inst, 1)) {
192                                 progress = true;
193                                 break;
194                         }
195 
196                         /* FADD(a, FSUB(0, b)) -> FSUB(a, b) */
197                         if (inst->src[1].file == QFILE_TEMP &&
198                             c->defs[inst->src[1].index] &&
199                             c->defs[inst->src[1].index]->op == QOP_FSUB) {
200                                 struct qinst *fsub = c->defs[inst->src[1].index];
201                                 if (is_zero(c, fsub->src[0])) {
202                                         dump_from(c, inst);
203                                         inst->op = QOP_FSUB;
204                                         inst->src[1] = fsub->src[1];
205                                         progress = true;
206                                         dump_to(c, inst);
207                                         break;
208                                 }
209                         }
210 
211                         /* FADD(FSUB(0, b), a) -> FSUB(a, b) */
212                         if (inst->src[0].file == QFILE_TEMP &&
213                             c->defs[inst->src[0].index] &&
214                             c->defs[inst->src[0].index]->op == QOP_FSUB) {
215                                 struct qinst *fsub = c->defs[inst->src[0].index];
216                                 if (is_zero(c, fsub->src[0])) {
217                                         dump_from(c, inst);
218                                         inst->op = QOP_FSUB;
219                                         inst->src[0] = inst->src[1];
220                                         inst->src[1] = fsub->src[1];
221                                         dump_to(c, inst);
222                                         progress = true;
223                                         break;
224                                 }
225                         }
226                         break;
227 
228                 case QOP_FMUL:
229                         if (!inst->dst.pack &&
230                             (replace_x_0_with_0(c, inst, 0) ||
231                              replace_x_0_with_0(c, inst, 1) ||
232                              fmul_replace_one(c, inst, 0) ||
233                              fmul_replace_one(c, inst, 1))) {
234                                 progress = true;
235                                 break;
236                         }
237                         break;
238 
239                 case QOP_MUL24:
240                         if (!inst->dst.pack &&
241                             (replace_x_0_with_0(c, inst, 0) ||
242                              replace_x_0_with_0(c, inst, 1))) {
243                                 progress = true;
244                                 break;
245                         }
246                         break;
247 
248                 case QOP_AND:
249                         if (replace_x_0_with_0(c, inst, 0) ||
250                             replace_x_0_with_0(c, inst, 1)) {
251                                 progress = true;
252                                 break;
253                         }
254 
255                         if (is_constant_value(c, inst->src[0], ~0)) {
256                                 replace_with_mov(c, inst, inst->src[1]);
257                                 progress = true;
258                                 break;
259                         }
260                         if (is_constant_value(c, inst->src[1], ~0)) {
261                                 replace_with_mov(c, inst, inst->src[0]);
262                                 progress = true;
263                                 break;
264                         }
265                         break;
266 
267                 case QOP_OR:
268                         if (replace_x_0_with_x(c, inst, 0) ||
269                             replace_x_0_with_x(c, inst, 1)) {
270                                 progress = true;
271                                 break;
272                         }
273                         break;
274 
275                 case QOP_RCP:
276                         if (is_1f(c, inst->src[0])) {
277                                 replace_with_mov(c, inst, inst->src[0]);
278                                 progress = true;
279                                 break;
280                         }
281                         break;
282 
283                 default:
284                         break;
285                 }
286         }
287 
288         return progress;
289 }
290