aboutsummaryrefslogtreecommitdiffstats
path: root/src/compiler/glsl/lower_precision.cpp
blob: 332cd50cc7a6bf7191ef19a1c4c0cca4ccd5d788 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
/*
 * Copyright © 2019 Google, Inc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

/**
 * \file lower_precision.cpp
 */

#include "main/macros.h"
#include "compiler/glsl_types.h"
#include "ir.h"
#include "ir_builder.h"
#include "ir_optimization.h"
#include "ir_rvalue_visitor.h"
#include "util/half_float.h"
#include "util/set.h"
#include "util/hash_table.h"
#include <vector>

namespace {

class find_precision_visitor : public ir_rvalue_enter_visitor {
public:
   find_precision_visitor();
   ~find_precision_visitor();

   virtual void handle_rvalue(ir_rvalue **rvalue);
   virtual ir_visitor_status visit_enter(ir_call *ir);

   ir_function_signature *map_builtin(ir_function_signature *sig);

   bool progress;

   /* Set of rvalues that can be lowered. This will be filled in by
    * find_lowerable_rvalues_visitor. Only the root node of a lowerable section
    * will be added to this set.
    */
   struct set *lowerable_rvalues;

   /**
    * A mapping of builtin signature functions to lowered versions. This is
    * filled in lazily when a lowered version is needed.
    */
   struct hash_table *lowered_builtins;
   /**
    * A temporary hash table only used in order to clone functions.
    */
   struct hash_table *clone_ht;

   void *lowered_builtin_mem_ctx;
};

class find_lowerable_rvalues_visitor : public ir_hierarchical_visitor {
public:
   enum can_lower_state {
      UNKNOWN,
      CANT_LOWER,
      SHOULD_LOWER,
   };

   enum parent_relation {
      /* The parent performs a further operation involving the result from the
       * child and can be lowered along with it.
       */
      COMBINED_OPERATION,
      /* The parent instruction’s operation is independent of the child type so
       * the child should be lowered separately.
       */
      INDEPENDENT_OPERATION,
   };

   struct stack_entry {
      ir_instruction *instr;
      enum can_lower_state state;
      /* List of child rvalues that can be lowered. When this stack entry is
       * popped, if this node itself can’t be lowered than all of the children
       * are root nodes to lower so we will add them to lowerable_rvalues.
       * Otherwise if this node can also be lowered then we won’t add the
       * children because we only want to add the topmost lowerable nodes to
       * lowerable_rvalues and the children will be lowered as part of lowering
       * this node.
       */
      std::vector<ir_instruction *> lowerable_children;
   };

   find_lowerable_rvalues_visitor(struct set *result);

   static void stack_enter(class ir_instruction *ir, void *data);
   static void stack_leave(class ir_instruction *ir, void *data);

   virtual ir_visitor_status visit(ir_constant *ir);
   virtual ir_visitor_status visit(ir_dereference_variable *ir);

   virtual ir_visitor_status visit_enter(ir_dereference_record *ir);
   virtual ir_visitor_status visit_enter(ir_dereference_array *ir);
   virtual ir_visitor_status visit_enter(ir_texture *ir);
   virtual ir_visitor_status visit_enter(ir_expression *ir);

   virtual ir_visitor_status visit_leave(ir_assignment *ir);
   virtual ir_visitor_status visit_leave(ir_call *ir);

   static can_lower_state handle_precision(const glsl_type *type,
                                           int precision);

   static parent_relation get_parent_relation(ir_instruction *parent,
                                              ir_instruction *child);

   std::vector<stack_entry> stack;
   struct set *lowerable_rvalues;

   void pop_stack_entry();
   void add_lowerable_children(const stack_entry &entry);
};

class lower_precision_visitor : public ir_rvalue_visitor {
public:
   virtual void handle_rvalue(ir_rvalue **rvalue);
   virtual ir_visitor_status visit_enter(ir_dereference_array *);
   virtual ir_visitor_status visit_enter(ir_dereference_record *);
   virtual ir_visitor_status visit_enter(ir_call *ir);
   virtual ir_visitor_status visit_enter(ir_texture *ir);
   virtual ir_visitor_status visit_leave(ir_expression *);
};

bool
can_lower_type(const glsl_type *type)
{
   /* Don’t lower any expressions involving non-float types except bool and
    * texture samplers. This will rule out operations that change the type such
    * as conversion to ints. Instead it will end up lowering the arguments
    * instead and adding a final conversion to float32. We want to handle
    * boolean types so that it will do comparisons as 16-bit.
    */

   switch (type->base_type) {
   case GLSL_TYPE_FLOAT:
   case GLSL_TYPE_BOOL:
   case GLSL_TYPE_SAMPLER:
      return true;

   default:
      return false;
   }
}

find_lowerable_rvalues_visitor::find_lowerable_rvalues_visitor(struct set *res)
{
   lowerable_rvalues = res;
   callback_enter = stack_enter;
   callback_leave = stack_leave;
   data_enter = this;
   data_leave = this;
}

void
find_lowerable_rvalues_visitor::stack_enter(class ir_instruction *ir,
                                            void *data)
{
   find_lowerable_rvalues_visitor *state =
      (find_lowerable_rvalues_visitor *) data;

   /* Add a new stack entry for this instruction */
   stack_entry entry;

   entry.instr = ir;
   entry.state = state->in_assignee ? CANT_LOWER : UNKNOWN;

   state->stack.push_back(entry);
}

void
find_lowerable_rvalues_visitor::add_lowerable_children(const stack_entry &entry)
{
   /* We can’t lower this node so if there were any pending children then they
    * are all root lowerable nodes and we should add them to the set.
    */
   for (auto &it : entry.lowerable_children)
      _mesa_set_add(lowerable_rvalues, it);
}

void
find_lowerable_rvalues_visitor::pop_stack_entry()
{
   const stack_entry &entry = stack.back();

   if (stack.size() >= 2) {
      /* Combine this state into the parent state, unless the parent operation
       * doesn’t have any relation to the child operations
       */
      stack_entry &parent = stack.end()[-2];
      parent_relation rel = get_parent_relation(parent.instr, entry.instr);

      if (rel == COMBINED_OPERATION) {
         switch (entry.state) {
         case CANT_LOWER:
            parent.state = CANT_LOWER;
            break;
         case SHOULD_LOWER:
            if (parent.state == UNKNOWN)
               parent.state = SHOULD_LOWER;
            break;
         case UNKNOWN:
            break;
         }
      }
   }

   if (entry.state == SHOULD_LOWER) {
      ir_rvalue *rv = entry.instr->as_rvalue();

      if (rv == NULL) {
         add_lowerable_children(entry);
      } else if (stack.size() >= 2) {
         stack_entry &parent = stack.end()[-2];

         switch (get_parent_relation(parent.instr, rv)) {
         case COMBINED_OPERATION:
            /* We only want to add the toplevel lowerable instructions to the
             * lowerable set. Therefore if there is a parent then instead of
             * adding this instruction to the set we will queue depending on
             * the result of the parent instruction.
             */
            parent.lowerable_children.push_back(entry.instr);
            break;
         case INDEPENDENT_OPERATION:
            _mesa_set_add(lowerable_rvalues, rv);
            break;
         }
      } else {
         /* This is a toplevel node so add it directly to the lowerable
          * set.
          */
         _mesa_set_add(lowerable_rvalues, rv);
      }
   } else if (entry.state == CANT_LOWER) {
      add_lowerable_children(entry);
   }

   stack.pop_back();
}

void
find_lowerable_rvalues_visitor::stack_leave(class ir_instruction *ir,
                                            void *data)
{
   find_lowerable_rvalues_visitor *state =
      (find_lowerable_rvalues_visitor *) data;

   state->pop_stack_entry();
}

enum find_lowerable_rvalues_visitor::can_lower_state
find_lowerable_rvalues_visitor::handle_precision(const glsl_type *type,
                                                 int precision)
{
   if (!can_lower_type(type))
      return CANT_LOWER;

   switch (precision) {
   case GLSL_PRECISION_NONE:
      return UNKNOWN;
   case GLSL_PRECISION_HIGH:
      return CANT_LOWER;
   case GLSL_PRECISION_MEDIUM:
   case GLSL_PRECISION_LOW:
      return SHOULD_LOWER;
   }

   return CANT_LOWER;
}

enum find_lowerable_rvalues_visitor::parent_relation
find_lowerable_rvalues_visitor::get_parent_relation(ir_instruction *parent,
                                                    ir_instruction *child)
{
   /* If the parent is a dereference instruction then the only child could be
    * for example an array dereference and that should be lowered independently
    * of the parent.
    */
   if (parent->as_dereference())
      return INDEPENDENT_OPERATION;

   /* The precision of texture sampling depend on the precision of the sampler.
    * The rest of the arguments don’t matter so we can treat it as an
    * independent operation.
    */
   if (parent->as_texture())
      return INDEPENDENT_OPERATION;

   return COMBINED_OPERATION;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit(ir_constant *ir)
{
   stack_enter(ir, this);

   if (!can_lower_type(ir->type))
      stack.back().state = CANT_LOWER;

   stack_leave(ir, this);

   return visit_continue;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit(ir_dereference_variable *ir)
{
   stack_enter(ir, this);

   if (stack.back().state == UNKNOWN)
      stack.back().state = handle_precision(ir->type, ir->precision());

   stack_leave(ir, this);

   return visit_continue;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit_enter(ir_dereference_record *ir)
{
   ir_hierarchical_visitor::visit_enter(ir);

   if (stack.back().state == UNKNOWN)
      stack.back().state = handle_precision(ir->type, ir->precision());

   return visit_continue;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit_enter(ir_dereference_array *ir)
{
   ir_hierarchical_visitor::visit_enter(ir);

   if (stack.back().state == UNKNOWN)
      stack.back().state = handle_precision(ir->type, ir->precision());

   return visit_continue;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit_enter(ir_texture *ir)
{
   ir_hierarchical_visitor::visit_enter(ir);

   if (stack.back().state == UNKNOWN) {
      /* The precision of the sample value depends on the precision of the
       * sampler.
       */
      stack.back().state = handle_precision(ir->type,
                                            ir->sampler->precision());
   }

   return visit_continue;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit_enter(ir_expression *ir)
{
   ir_hierarchical_visitor::visit_enter(ir);

   if (!can_lower_type(ir->type))
      stack.back().state = CANT_LOWER;

   /* Don't lower precision for derivative calculations */
   if (ir->operation == ir_unop_dFdx ||
         ir->operation == ir_unop_dFdx_coarse ||
         ir->operation == ir_unop_dFdx_fine ||
         ir->operation == ir_unop_dFdy ||
         ir->operation == ir_unop_dFdy_coarse ||
         ir->operation == ir_unop_dFdy_fine) {
      stack.back().state = CANT_LOWER;
   }

   return visit_continue;
}

static bool
is_lowerable_builtin(ir_call *ir,
                     const struct set *lowerable_rvalues)
{
   if (!ir->callee->is_builtin())
      return false;

   assert(ir->callee->return_precision == GLSL_PRECISION_NONE);

   foreach_in_list(ir_rvalue, param, &ir->actual_parameters) {
      if (!param->as_constant() &&
          _mesa_set_search(lowerable_rvalues, param) == NULL)
         return false;
   }

   return true;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit_leave(ir_call *ir)
{
   ir_hierarchical_visitor::visit_leave(ir);

   /* Special case for handling temporary variables generated by the compiler
    * for function calls. If we assign to one of these using a function call
    * that has a lowerable return type then we can assume the temporary
    * variable should have a medium precision too.
    */

   /* Do nothing if the return type is void. */
   if (!ir->return_deref)
      return visit_continue;

   ir_variable *var = ir->return_deref->variable_referenced();

   assert(var->data.mode == ir_var_temporary);

   unsigned return_precision = ir->callee->return_precision;

   /* If the call is to a builtin, then the function won’t have a return
    * precision and we should determine it from the precision of the arguments.
    */
   if (is_lowerable_builtin(ir, lowerable_rvalues))
      return_precision = GLSL_PRECISION_MEDIUM;

   can_lower_state lower_state =
      handle_precision(var->type, return_precision);

   if (lower_state == SHOULD_LOWER) {
      /* There probably shouldn’t be any situations where multiple ir_call
       * instructions write to the same temporary?
       */
      assert(var->data.precision == GLSL_PRECISION_NONE);
      var->data.precision = GLSL_PRECISION_MEDIUM;
   } else {
      var->data.precision = GLSL_PRECISION_HIGH;
   }

   return visit_continue;
}

ir_visitor_status
find_lowerable_rvalues_visitor::visit_leave(ir_assignment *ir)
{
   ir_hierarchical_visitor::visit_leave(ir);

   /* Special case for handling temporary variables generated by the compiler.
    * If we assign to one of these using a lowered precision then we can assume
    * the temporary variable should have a medium precision too.
    */
   ir_variable *var = ir->lhs->variable_referenced();

   if (var->data.mode == ir_var_temporary) {
      if (_mesa_set_search(lowerable_rvalues, ir->rhs)) {
         /* Only override the precision if this is the first assignment. For
          * temporaries such as the ones generated for the ?: operator there
          * can be multiple assignments with different precisions. This way we
          * get the highest precision of all of the assignments.
          */
         if (var->data.precision == GLSL_PRECISION_NONE)
            var->data.precision = GLSL_PRECISION_MEDIUM;
      } else if (!ir->rhs->as_constant()) {
         var->data.precision = GLSL_PRECISION_HIGH;
      }
   }

   return visit_continue;
}

void
find_lowerable_rvalues(exec_list *instructions,
                       struct set *result)
{
   find_lowerable_rvalues_visitor v(result);

   visit_list_elements(&v, instructions);

   assert(v.stack.empty());
}

static ir_rvalue *
convert_precision(int op, ir_rvalue *ir)
{
   unsigned base_type = (op == ir_unop_f2fmp ?
                        GLSL_TYPE_FLOAT16 : GLSL_TYPE_FLOAT);
   const glsl_type *desired_type;
   desired_type = glsl_type::get_instance(base_type,
                             ir->type->vector_elements,
                             ir->type->matrix_columns);

   void *mem_ctx = ralloc_parent(ir);
   return new(mem_ctx) ir_expression(op, desired_type, ir, NULL);
}

void
lower_precision_visitor::handle_rvalue(ir_rvalue **rvalue)
{
   ir_rvalue *ir = *rvalue;

   if (ir == NULL)
      return;

   if (ir->as_dereference()) {
      if (!ir->type->is_boolean())
         *rvalue = convert_precision(ir_unop_f2fmp, ir);
   } else if (ir->type->is_float()) {
      ir->type = glsl_type::get_instance(GLSL_TYPE_FLOAT16,
                                         ir->type->vector_elements,
                                         ir->type->matrix_columns,
                                         ir->type->explicit_stride,
                                         ir->type->interface_row_major);

      ir_constant *const_ir = ir->as_constant();

      if (const_ir) {
         ir_constant_data value;

         for (unsigned i = 0; i < ARRAY_SIZE(value.f16); i++)
            value.f16[i] = _mesa_float_to_half(const_ir->value.f[i]);

         const_ir->value = value;
      }
   }
}

ir_visitor_status
lower_precision_visitor::visit_enter(ir_dereference_record *ir)
{
   /* We don’t want to lower the variable */
   return visit_continue_with_parent;
}

ir_visitor_status
lower_precision_visitor::visit_enter(ir_dereference_array *ir)
{
   /* We don’t want to convert the array index or the variable. If the array
    * index itself is lowerable that will be handled separately.
    */
   return visit_continue_with_parent;
}

ir_visitor_status
lower_precision_visitor::visit_enter(ir_call *ir)
{
   /* We don’t want to convert the arguments. These will be handled separately.
    */
   return visit_continue_with_parent;
}

ir_visitor_status
lower_precision_visitor::visit_enter(ir_texture *ir)
{
   /* We don’t want to convert the arguments. These will be handled separately.
    */
   return visit_continue_with_parent;
}

ir_visitor_status
lower_precision_visitor::visit_leave(ir_expression *ir)
{
   ir_rvalue_visitor::visit_leave(ir);

   /* If the expression is a conversion operation to or from bool then fix the
    * operation.
    */
   switch (ir->operation) {
   case ir_unop_b2f:
      ir->operation = ir_unop_b2f16;
      break;
   case ir_unop_f2b:
      ir->operation = ir_unop_f162b;
      break;
   default:
      break;
   }

   return visit_continue;
}

void
find_precision_visitor::handle_rvalue(ir_rvalue **rvalue)
{
   /* Checking the precision of rvalue can be lowered first throughout
    * find_lowerable_rvalues_visitor.
    * Once it found the precision of rvalue can be lowered, then we can
    * add conversion f2fmp through lower_precision_visitor.
    */
   if (*rvalue == NULL)
      return;

   struct set_entry *entry = _mesa_set_search(lowerable_rvalues, *rvalue);

   if (!entry)
      return;

   _mesa_set_remove(lowerable_rvalues, entry);

   /* If the entire expression is just a variable dereference then trying to
    * lower it will just directly add pointless to and from conversions without
    * any actual operation in-between. Although these will eventually get
    * optimised out, avoiding generating them here also avoids breaking inout
    * parameters to functions.
    */
   if ((*rvalue)->as_dereference())
      return;

   lower_precision_visitor v;

   (*rvalue)->accept(&v);
   v.handle_rvalue(rvalue);

   /* We don’t need to add the final conversion if the final type has been
    * converted to bool
    */
   if ((*rvalue)->type->base_type != GLSL_TYPE_BOOL)
      *rvalue = convert_precision(ir_unop_f162f, *rvalue);

   progress = true;
}

ir_visitor_status
find_precision_visitor::visit_enter(ir_call *ir)
{
   ir_rvalue_enter_visitor::visit_enter(ir);

   /* If this is a call to a builtin and the find_lowerable_rvalues_visitor
    * overrode the precision of the temporary return variable, then we can
    * replace the builtin implementation with a lowered version.
    */

   if (!ir->callee->is_builtin() ||
       ir->return_deref == NULL ||
       ir->return_deref->variable_referenced()->data.precision !=
       GLSL_PRECISION_MEDIUM)
      return visit_continue;

   ir->callee = map_builtin(ir->callee);
   ir->generate_inline(ir);
   ir->remove();

   return visit_continue_with_parent;
}

ir_function_signature *
find_precision_visitor::map_builtin(ir_function_signature *sig)
{
   if (lowered_builtins == NULL) {
      lowered_builtins = _mesa_pointer_hash_table_create(NULL);
      clone_ht =_mesa_pointer_hash_table_create(NULL);
      lowered_builtin_mem_ctx = ralloc_context(NULL);
   } else {
      struct hash_entry *entry = _mesa_hash_table_search(lowered_builtins, sig);
      if (entry)
         return (ir_function_signature *) entry->data;
   }

   ir_function_signature *lowered_sig =
      sig->clone(lowered_builtin_mem_ctx, clone_ht);

   foreach_in_list(ir_variable, param, &lowered_sig->parameters) {
      param->data.precision = GLSL_PRECISION_MEDIUM;
   }

   lower_precision(&lowered_sig->body);

   _mesa_hash_table_clear(clone_ht, NULL);

   _mesa_hash_table_insert(lowered_builtins, sig, lowered_sig);

   return lowered_sig;
}

find_precision_visitor::find_precision_visitor()
   : progress(false),
     lowerable_rvalues(_mesa_pointer_set_create(NULL)),
     lowered_builtins(NULL),
     clone_ht(NULL),
     lowered_builtin_mem_ctx(NULL)
{
}

find_precision_visitor::~find_precision_visitor()
{
   _mesa_set_destroy(lowerable_rvalues, NULL);

   if (lowered_builtins) {
      _mesa_hash_table_destroy(lowered_builtins, NULL);
      _mesa_hash_table_destroy(clone_ht, NULL);
      ralloc_free(lowered_builtin_mem_ctx);
   }
}

}

bool
lower_precision(exec_list *instructions)
{
   find_precision_visitor v;

   find_lowerable_rvalues(instructions, v.lowerable_rvalues);

   visit_list_elements(&v, instructions);

   return v.progress;
}