1 /*
2 * Copyright © 2010 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 /**
25 * \file opt_algebraic.cpp
26 *
27 * Takes advantage of association, commutivity, and other algebraic
28 * properties to simplify expressions.
29 */
30
31 #include "ir.h"
32 #include "ir_visitor.h"
33 #include "ir_rvalue_visitor.h"
34 #include "ir_optimization.h"
35 #include "glsl_types.h"
36
37 namespace {
38
39 /**
40 * Visitor class for replacing expressions with ir_constant values.
41 */
42
43 class ir_algebraic_visitor : public ir_rvalue_visitor {
44 public:
ir_algebraic_visitor()45 ir_algebraic_visitor()
46 {
47 this->progress = false;
48 this->mem_ctx = NULL;
49 }
50
~ir_algebraic_visitor()51 virtual ~ir_algebraic_visitor()
52 {
53 }
54
55 ir_rvalue *handle_expression(ir_expression *ir);
56 void handle_rvalue(ir_rvalue **rvalue);
57 bool reassociate_constant(ir_expression *ir1,
58 int const_index,
59 ir_constant *constant,
60 ir_expression *ir2);
61 void reassociate_operands(ir_expression *ir1,
62 int op1,
63 ir_expression *ir2,
64 int op2);
65 ir_rvalue *swizzle_if_required(ir_expression *expr,
66 ir_rvalue *operand);
67
68 void *mem_ctx;
69
70 bool progress;
71 };
72
73 } /* unnamed namespace */
74
75 static inline bool
is_vec_zero(ir_constant * ir)76 is_vec_zero(ir_constant *ir)
77 {
78 return (ir == NULL) ? false : ir->is_zero();
79 }
80
81 static inline bool
is_vec_one(ir_constant * ir)82 is_vec_one(ir_constant *ir)
83 {
84 return (ir == NULL) ? false : ir->is_one();
85 }
86
87 static inline bool
is_vec_basis(ir_constant * ir)88 is_vec_basis(ir_constant *ir)
89 {
90 return (ir == NULL) ? false : ir->is_basis();
91 }
92
93 static void
update_type(ir_expression * ir)94 update_type(ir_expression *ir)
95 {
96 if (ir->operands[0]->type->is_vector())
97 ir->type = ir->operands[0]->type;
98 else
99 ir->type = ir->operands[1]->type;
100 }
101
102 void
reassociate_operands(ir_expression * ir1,int op1,ir_expression * ir2,int op2)103 ir_algebraic_visitor::reassociate_operands(ir_expression *ir1,
104 int op1,
105 ir_expression *ir2,
106 int op2)
107 {
108 ir_rvalue *temp = ir2->operands[op2];
109 ir2->operands[op2] = ir1->operands[op1];
110 ir1->operands[op1] = temp;
111
112 /* Update the type of ir2. The type of ir1 won't have changed --
113 * base types matched, and at least one of the operands of the 2
114 * binops is still a vector if any of them were.
115 */
116 update_type(ir2);
117
118 this->progress = true;
119 }
120
121 /**
122 * Reassociates a constant down a tree of adds or multiplies.
123 *
124 * Consider (2 * (a * (b * 0.5))). We want to send up with a * b.
125 */
126 bool
reassociate_constant(ir_expression * ir1,int const_index,ir_constant * constant,ir_expression * ir2)127 ir_algebraic_visitor::reassociate_constant(ir_expression *ir1, int const_index,
128 ir_constant *constant,
129 ir_expression *ir2)
130 {
131 if (!ir2 || ir1->operation != ir2->operation)
132 return false;
133
134 /* Don't want to even think about matrices. */
135 if (ir1->operands[0]->type->is_matrix() ||
136 ir1->operands[1]->type->is_matrix() ||
137 ir2->operands[0]->type->is_matrix() ||
138 ir2->operands[1]->type->is_matrix())
139 return false;
140
141 ir_constant *ir2_const[2];
142 ir2_const[0] = ir2->operands[0]->constant_expression_value();
143 ir2_const[1] = ir2->operands[1]->constant_expression_value();
144
145 if (ir2_const[0] && ir2_const[1])
146 return false;
147
148 if (ir2_const[0]) {
149 reassociate_operands(ir1, const_index, ir2, 1);
150 return true;
151 } else if (ir2_const[1]) {
152 reassociate_operands(ir1, const_index, ir2, 0);
153 return true;
154 }
155
156 if (reassociate_constant(ir1, const_index, constant,
157 ir2->operands[0]->as_expression())) {
158 update_type(ir2);
159 return true;
160 }
161
162 if (reassociate_constant(ir1, const_index, constant,
163 ir2->operands[1]->as_expression())) {
164 update_type(ir2);
165 return true;
166 }
167
168 return false;
169 }
170
171 /* When eliminating an expression and just returning one of its operands,
172 * we may need to swizzle that operand out to a vector if the expression was
173 * vector type.
174 */
175 ir_rvalue *
swizzle_if_required(ir_expression * expr,ir_rvalue * operand)176 ir_algebraic_visitor::swizzle_if_required(ir_expression *expr,
177 ir_rvalue *operand)
178 {
179 if (expr->type->is_vector() && operand->type->is_scalar()) {
180 return new(mem_ctx) ir_swizzle(operand, 0, 0, 0, 0,
181 expr->type->vector_elements);
182 } else
183 return operand;
184 }
185
186 ir_rvalue *
handle_expression(ir_expression * ir)187 ir_algebraic_visitor::handle_expression(ir_expression *ir)
188 {
189 ir_constant *op_const[2] = {NULL, NULL};
190 ir_expression *op_expr[2] = {NULL, NULL};
191 ir_expression *temp;
192 unsigned int i;
193
194 assert(ir->get_num_operands() <= 2);
195 for (i = 0; i < ir->get_num_operands(); i++) {
196 if (ir->operands[i]->type->is_matrix())
197 return ir;
198
199 op_const[i] = ir->operands[i]->constant_expression_value();
200 op_expr[i] = ir->operands[i]->as_expression();
201 }
202
203 if (this->mem_ctx == NULL)
204 this->mem_ctx = ralloc_parent(ir);
205
206 switch (ir->operation) {
207 case ir_unop_logic_not: {
208 enum ir_expression_operation new_op = ir_unop_logic_not;
209
210 if (op_expr[0] == NULL)
211 break;
212
213 switch (op_expr[0]->operation) {
214 case ir_binop_less: new_op = ir_binop_gequal; break;
215 case ir_binop_greater: new_op = ir_binop_lequal; break;
216 case ir_binop_lequal: new_op = ir_binop_greater; break;
217 case ir_binop_gequal: new_op = ir_binop_less; break;
218 case ir_binop_equal: new_op = ir_binop_nequal; break;
219 case ir_binop_nequal: new_op = ir_binop_equal; break;
220 case ir_binop_all_equal: new_op = ir_binop_any_nequal; break;
221 case ir_binop_any_nequal: new_op = ir_binop_all_equal; break;
222
223 default:
224 /* The default case handler is here to silence a warning from GCC.
225 */
226 break;
227 }
228
229 if (new_op != ir_unop_logic_not) {
230 this->progress = true;
231 return new(mem_ctx) ir_expression(new_op,
232 ir->type,
233 op_expr[0]->operands[0],
234 op_expr[0]->operands[1]);
235 }
236
237 break;
238 }
239
240 case ir_binop_add:
241 if (is_vec_zero(op_const[0])) {
242 this->progress = true;
243 return swizzle_if_required(ir, ir->operands[1]);
244 }
245 if (is_vec_zero(op_const[1])) {
246 this->progress = true;
247 return swizzle_if_required(ir, ir->operands[0]);
248 }
249
250 /* Reassociate addition of constants so that we can do constant
251 * folding.
252 */
253 if (op_const[0] && !op_const[1])
254 reassociate_constant(ir, 0, op_const[0],
255 ir->operands[1]->as_expression());
256 if (op_const[1] && !op_const[0])
257 reassociate_constant(ir, 1, op_const[1],
258 ir->operands[0]->as_expression());
259 break;
260
261 case ir_binop_sub:
262 if (is_vec_zero(op_const[0])) {
263 this->progress = true;
264 temp = new(mem_ctx) ir_expression(ir_unop_neg,
265 ir->operands[1]->type,
266 ir->operands[1],
267 NULL);
268 return swizzle_if_required(ir, temp);
269 }
270 if (is_vec_zero(op_const[1])) {
271 this->progress = true;
272 return swizzle_if_required(ir, ir->operands[0]);
273 }
274 break;
275
276 case ir_binop_mul:
277 if (is_vec_one(op_const[0])) {
278 this->progress = true;
279 return swizzle_if_required(ir, ir->operands[1]);
280 }
281 if (is_vec_one(op_const[1])) {
282 this->progress = true;
283 return swizzle_if_required(ir, ir->operands[0]);
284 }
285
286 if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1])) {
287 this->progress = true;
288 return ir_constant::zero(ir, ir->type);
289 }
290
291 /* Reassociate multiplication of constants so that we can do
292 * constant folding.
293 */
294 if (op_const[0] && !op_const[1])
295 reassociate_constant(ir, 0, op_const[0],
296 ir->operands[1]->as_expression());
297 if (op_const[1] && !op_const[0])
298 reassociate_constant(ir, 1, op_const[1],
299 ir->operands[0]->as_expression());
300
301 break;
302
303 case ir_binop_div:
304 if (is_vec_one(op_const[0]) && ir->type->base_type == GLSL_TYPE_FLOAT) {
305 this->progress = true;
306 temp = new(mem_ctx) ir_expression(ir_unop_rcp,
307 ir->operands[1]->type,
308 ir->operands[1],
309 NULL);
310 return swizzle_if_required(ir, temp);
311 }
312 if (is_vec_one(op_const[1])) {
313 this->progress = true;
314 return swizzle_if_required(ir, ir->operands[0]);
315 }
316 break;
317
318 case ir_binop_dot:
319 if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1])) {
320 this->progress = true;
321 return ir_constant::zero(mem_ctx, ir->type);
322 }
323 if (is_vec_basis(op_const[0])) {
324 this->progress = true;
325 unsigned component = 0;
326 for (unsigned c = 0; c < op_const[0]->type->vector_elements; c++) {
327 if (op_const[0]->value.f[c] == 1.0)
328 component = c;
329 }
330 return new(mem_ctx) ir_swizzle(ir->operands[1], component, 0, 0, 0, 1);
331 }
332 if (is_vec_basis(op_const[1])) {
333 this->progress = true;
334 unsigned component = 0;
335 for (unsigned c = 0; c < op_const[1]->type->vector_elements; c++) {
336 if (op_const[1]->value.f[c] == 1.0)
337 component = c;
338 }
339 return new(mem_ctx) ir_swizzle(ir->operands[0], component, 0, 0, 0, 1);
340 }
341 break;
342
343 case ir_binop_logic_and:
344 /* FINISHME: Also simplify (a && a) to (a). */
345 if (is_vec_one(op_const[0])) {
346 this->progress = true;
347 return ir->operands[1];
348 } else if (is_vec_one(op_const[1])) {
349 this->progress = true;
350 return ir->operands[0];
351 } else if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1])) {
352 this->progress = true;
353 return ir_constant::zero(mem_ctx, ir->type);
354 }
355 break;
356
357 case ir_binop_logic_xor:
358 /* FINISHME: Also simplify (a ^^ a) to (false). */
359 if (is_vec_zero(op_const[0])) {
360 this->progress = true;
361 return ir->operands[1];
362 } else if (is_vec_zero(op_const[1])) {
363 this->progress = true;
364 return ir->operands[0];
365 } else if (is_vec_one(op_const[0])) {
366 this->progress = true;
367 return new(mem_ctx) ir_expression(ir_unop_logic_not, ir->type,
368 ir->operands[1], NULL);
369 } else if (is_vec_one(op_const[1])) {
370 this->progress = true;
371 return new(mem_ctx) ir_expression(ir_unop_logic_not, ir->type,
372 ir->operands[0], NULL);
373 }
374 break;
375
376 case ir_binop_logic_or:
377 /* FINISHME: Also simplify (a || a) to (a). */
378 if (is_vec_zero(op_const[0])) {
379 this->progress = true;
380 return ir->operands[1];
381 } else if (is_vec_zero(op_const[1])) {
382 this->progress = true;
383 return ir->operands[0];
384 } else if (is_vec_one(op_const[0]) || is_vec_one(op_const[1])) {
385 ir_constant_data data;
386
387 for (unsigned i = 0; i < 16; i++)
388 data.b[i] = true;
389
390 this->progress = true;
391 return new(mem_ctx) ir_constant(ir->type, &data);
392 }
393 break;
394
395 case ir_unop_rcp:
396 if (op_expr[0] && op_expr[0]->operation == ir_unop_rcp) {
397 this->progress = true;
398 return op_expr[0]->operands[0];
399 }
400
401 /* FINISHME: We should do rcp(rsq(x)) -> sqrt(x) for some
402 * backends, except that some backends will have done sqrt ->
403 * rcp(rsq(x)) and we don't want to undo it for them.
404 */
405
406 /* As far as we know, all backends are OK with rsq. */
407 if (op_expr[0] && op_expr[0]->operation == ir_unop_sqrt) {
408 this->progress = true;
409 temp = new(mem_ctx) ir_expression(ir_unop_rsq,
410 op_expr[0]->operands[0]->type,
411 op_expr[0]->operands[0],
412 NULL);
413 return swizzle_if_required(ir, temp);
414 }
415
416 break;
417
418 default:
419 break;
420 }
421
422 return ir;
423 }
424
425 void
handle_rvalue(ir_rvalue ** rvalue)426 ir_algebraic_visitor::handle_rvalue(ir_rvalue **rvalue)
427 {
428 if (!*rvalue)
429 return;
430
431 ir_expression *expr = (*rvalue)->as_expression();
432 if (!expr || expr->operation == ir_quadop_vector)
433 return;
434
435 *rvalue = handle_expression(expr);
436 }
437
438 bool
do_algebraic(exec_list * instructions)439 do_algebraic(exec_list *instructions)
440 {
441 ir_algebraic_visitor v;
442
443 visit_list_elements(&v, instructions);
444
445 return v.progress;
446 }
447