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/**
25 * \file ir_array_refcount.cpp
26 *
27 * Provides a visitor which produces a list of variables referenced.
28 */
29
30#include "ir.h"
31#include "ir_visitor.h"
32#include "ir_array_refcount.h"
33#include "compiler/glsl_types.h"
34#include "util/hash_table.h"
35
36ir_array_refcount_visitor::ir_array_refcount_visitor()
37   : last_array_deref(0), derefs(0), num_derefs(0), derefs_size(0)
38{
39   this->mem_ctx = ralloc_context(NULL);
40   this->ht = _mesa_pointer_hash_table_create(NULL);
41}
42
43static void
44free_entry(struct hash_entry *entry)
45{
46   ir_array_refcount_entry *ivre = (ir_array_refcount_entry *) entry->data;
47   delete ivre;
48}
49
50ir_array_refcount_visitor::~ir_array_refcount_visitor()
51{
52   ralloc_free(this->mem_ctx);
53   _mesa_hash_table_destroy(this->ht, free_entry);
54}
55
56ir_array_refcount_entry::ir_array_refcount_entry(ir_variable *var)
57   : var(var), is_referenced(false)
58{
59   num_bits = MAX2(1, var->type->arrays_of_arrays_size());
60   bits = new BITSET_WORD[BITSET_WORDS(num_bits)];
61   memset(bits, 0, BITSET_WORDS(num_bits) * sizeof(bits[0]));
62
63   /* Count the "depth" of the arrays-of-arrays. */
64   array_depth = 0;
65   for (const glsl_type *type = var->type;
66        type->is_array();
67        type = type->fields.array) {
68      array_depth++;
69   }
70}
71
72
73ir_array_refcount_entry::~ir_array_refcount_entry()
74{
75   delete [] bits;
76}
77
78ir_array_refcount_entry *
79ir_array_refcount_visitor::get_variable_entry(ir_variable *var)
80{
81   assert(var);
82
83   struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
84   if (e)
85      return (ir_array_refcount_entry *)e->data;
86
87   ir_array_refcount_entry *entry = new ir_array_refcount_entry(var);
88   _mesa_hash_table_insert(this->ht, var, entry);
89
90   return entry;
91}
92
93
94array_deref_range *
95ir_array_refcount_visitor::get_array_deref()
96{
97   if ((num_derefs + 1) * sizeof(array_deref_range) > derefs_size) {
98      void *ptr = reralloc_size(mem_ctx, derefs, derefs_size + 4096);
99
100      if (ptr == NULL)
101         return NULL;
102
103      derefs_size += 4096;
104      derefs = (array_deref_range *)ptr;
105   }
106
107   array_deref_range *d = &derefs[num_derefs];
108   num_derefs++;
109
110   return d;
111}
112
113ir_visitor_status
114ir_array_refcount_visitor::visit_enter(ir_dereference_array *ir)
115{
116   /* It could also be a vector or a matrix.  Individual elements of vectors
117    * are natrices are not tracked, so bail.
118    */
119   if (!ir->array->type->is_array())
120      return visit_continue;
121
122   /* If this array dereference is a child of an array dereference that was
123    * already visited, just continue on.  Otherwise, for an arrays-of-arrays
124    * dereference like x[1][2][3][4], we'd process the [1][2][3][4] sequence,
125    * the [1][2][3] sequence, the [1][2] sequence, and the [1] sequence.  This
126    * ensures that we only process the full sequence.
127    */
128   if (last_array_deref && last_array_deref->array == ir) {
129      last_array_deref = ir;
130      return visit_continue;
131   }
132
133   last_array_deref = ir;
134
135   num_derefs = 0;
136
137   ir_rvalue *rv = ir;
138   while (rv->ir_type == ir_type_dereference_array) {
139      ir_dereference_array *const deref = rv->as_dereference_array();
140
141      assert(deref != NULL);
142      assert(deref->array->type->is_array());
143
144      ir_rvalue *const array = deref->array;
145      const ir_constant *const idx = deref->array_index->as_constant();
146      array_deref_range *const dr = get_array_deref();
147
148      dr->size = array->type->array_size();
149
150      if (idx != NULL) {
151         dr->index = idx->get_int_component(0);
152      } else {
153         /* An unsized array can occur at the end of an SSBO.  We can't track
154          * accesses to such an array, so bail.
155          */
156         if (array->type->array_size() == 0)
157            return visit_continue;
158
159         dr->index = dr->size;
160      }
161
162      rv = array;
163   }
164
165   ir_dereference_variable *const var_deref = rv->as_dereference_variable();
166
167   /* If the array being dereferenced is not a variable, bail.  At the very
168    * least, ir_constant and ir_dereference_record are possible.
169    */
170   if (var_deref == NULL)
171      return visit_continue;
172
173   ir_array_refcount_entry *const entry =
174      this->get_variable_entry(var_deref->var);
175
176   if (entry == NULL)
177      return visit_stop;
178
179   link_util_mark_array_elements_referenced(derefs, num_derefs,
180                                            entry->array_depth,
181                                            entry->bits);
182
183   return visit_continue;
184}
185
186
187ir_visitor_status
188ir_array_refcount_visitor::visit(ir_dereference_variable *ir)
189{
190   ir_variable *const var = ir->variable_referenced();
191   ir_array_refcount_entry *entry = this->get_variable_entry(var);
192
193   entry->is_referenced = true;
194
195   return visit_continue;
196}
197
198
199ir_visitor_status
200ir_array_refcount_visitor::visit_enter(ir_function_signature *ir)
201{
202   /* We don't want to descend into the function parameters and
203    * dead-code eliminate them, so just accept the body here.
204    */
205   visit_list_elements(this, &ir->body);
206   return visit_continue_with_parent;
207}
208