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
ir_array_refcount_visitor()36 ir_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_hash_table_create(NULL, _mesa_hash_pointer,
41 _mesa_key_pointer_equal);
42 }
43
44 static void
free_entry(struct hash_entry * entry)45 free_entry(struct hash_entry *entry)
46 {
47 ir_array_refcount_entry *ivre = (ir_array_refcount_entry *) entry->data;
48 delete ivre;
49 }
50
~ir_array_refcount_visitor()51 ir_array_refcount_visitor::~ir_array_refcount_visitor()
52 {
53 ralloc_free(this->mem_ctx);
54 _mesa_hash_table_destroy(this->ht, free_entry);
55 }
56
ir_array_refcount_entry(ir_variable * var)57 ir_array_refcount_entry::ir_array_refcount_entry(ir_variable *var)
58 : var(var), is_referenced(false)
59 {
60 num_bits = MAX2(1, var->type->arrays_of_arrays_size());
61 bits = new BITSET_WORD[BITSET_WORDS(num_bits)];
62 memset(bits, 0, BITSET_WORDS(num_bits) * sizeof(bits[0]));
63
64 /* Count the "depth" of the arrays-of-arrays. */
65 array_depth = 0;
66 for (const glsl_type *type = var->type;
67 type->is_array();
68 type = type->fields.array) {
69 array_depth++;
70 }
71 }
72
73
~ir_array_refcount_entry()74 ir_array_refcount_entry::~ir_array_refcount_entry()
75 {
76 delete [] bits;
77 }
78
79
80 void
mark_array_elements_referenced(const array_deref_range * dr,unsigned count)81 ir_array_refcount_entry::mark_array_elements_referenced(const array_deref_range *dr,
82 unsigned count)
83 {
84 if (count != array_depth)
85 return;
86
87 mark_array_elements_referenced(dr, count, 1, 0);
88 }
89
90 void
mark_array_elements_referenced(const array_deref_range * dr,unsigned count,unsigned scale,unsigned linearized_index)91 ir_array_refcount_entry::mark_array_elements_referenced(const array_deref_range *dr,
92 unsigned count,
93 unsigned scale,
94 unsigned linearized_index)
95 {
96 /* Walk through the list of array dereferences in least- to
97 * most-significant order. Along the way, accumulate the current
98 * linearized offset and the scale factor for each array-of-.
99 */
100 for (unsigned i = 0; i < count; i++) {
101 if (dr[i].index < dr[i].size) {
102 linearized_index += dr[i].index * scale;
103 scale *= dr[i].size;
104 } else {
105 /* For each element in the current array, update the count and
106 * offset, then recurse to process the remaining arrays.
107 *
108 * There is some inefficency here if the last element in the
109 * array_deref_range list specifies the entire array. In that case,
110 * the loop will make recursive calls with count == 0. In the call,
111 * all that will happen is the bit will be set.
112 */
113 for (unsigned j = 0; j < dr[i].size; j++) {
114 mark_array_elements_referenced(&dr[i + 1],
115 count - (i + 1),
116 scale * dr[i].size,
117 linearized_index + (j * scale));
118 }
119
120 return;
121 }
122 }
123
124 BITSET_SET(bits, linearized_index);
125 }
126
127 ir_array_refcount_entry *
get_variable_entry(ir_variable * var)128 ir_array_refcount_visitor::get_variable_entry(ir_variable *var)
129 {
130 assert(var);
131
132 struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
133 if (e)
134 return (ir_array_refcount_entry *)e->data;
135
136 ir_array_refcount_entry *entry = new ir_array_refcount_entry(var);
137 _mesa_hash_table_insert(this->ht, var, entry);
138
139 return entry;
140 }
141
142
143 array_deref_range *
get_array_deref()144 ir_array_refcount_visitor::get_array_deref()
145 {
146 if ((num_derefs + 1) * sizeof(array_deref_range) > derefs_size) {
147 void *ptr = reralloc_size(mem_ctx, derefs, derefs_size + 4096);
148
149 if (ptr == NULL)
150 return NULL;
151
152 derefs_size += 4096;
153 derefs = (array_deref_range *)ptr;
154 }
155
156 array_deref_range *d = &derefs[num_derefs];
157 num_derefs++;
158
159 return d;
160 }
161
162 ir_visitor_status
visit_enter(ir_dereference_array * ir)163 ir_array_refcount_visitor::visit_enter(ir_dereference_array *ir)
164 {
165 /* It could also be a vector or a matrix. Individual elements of vectors
166 * are natrices are not tracked, so bail.
167 */
168 if (!ir->array->type->is_array())
169 return visit_continue;
170
171 /* If this array dereference is a child of an array dereference that was
172 * already visited, just continue on. Otherwise, for an arrays-of-arrays
173 * dereference like x[1][2][3][4], we'd process the [1][2][3][4] sequence,
174 * the [1][2][3] sequence, the [1][2] sequence, and the [1] sequence. This
175 * ensures that we only process the full sequence.
176 */
177 if (last_array_deref && last_array_deref->array == ir) {
178 last_array_deref = ir;
179 return visit_continue;
180 }
181
182 last_array_deref = ir;
183
184 num_derefs = 0;
185
186 ir_rvalue *rv = ir;
187 while (rv->ir_type == ir_type_dereference_array) {
188 ir_dereference_array *const deref = rv->as_dereference_array();
189
190 assert(deref != NULL);
191 assert(deref->array->type->is_array());
192
193 ir_rvalue *const array = deref->array;
194 const ir_constant *const idx = deref->array_index->as_constant();
195 array_deref_range *const dr = get_array_deref();
196
197 dr->size = array->type->array_size();
198
199 if (idx != NULL) {
200 dr->index = idx->get_int_component(0);
201 } else {
202 /* An unsized array can occur at the end of an SSBO. We can't track
203 * accesses to such an array, so bail.
204 */
205 if (array->type->array_size() == 0)
206 return visit_continue;
207
208 dr->index = dr->size;
209 }
210
211 rv = array;
212 }
213
214 ir_dereference_variable *const var_deref = rv->as_dereference_variable();
215
216 /* If the array being dereferenced is not a variable, bail. At the very
217 * least, ir_constant and ir_dereference_record are possible.
218 */
219 if (var_deref == NULL)
220 return visit_continue;
221
222 ir_array_refcount_entry *const entry =
223 this->get_variable_entry(var_deref->var);
224
225 if (entry == NULL)
226 return visit_stop;
227
228 entry->mark_array_elements_referenced(derefs, num_derefs);
229
230 return visit_continue;
231 }
232
233
234 ir_visitor_status
visit(ir_dereference_variable * ir)235 ir_array_refcount_visitor::visit(ir_dereference_variable *ir)
236 {
237 ir_variable *const var = ir->variable_referenced();
238 ir_array_refcount_entry *entry = this->get_variable_entry(var);
239
240 entry->is_referenced = true;
241
242 return visit_continue;
243 }
244
245
246 ir_visitor_status
visit_enter(ir_function_signature * ir)247 ir_array_refcount_visitor::visit_enter(ir_function_signature *ir)
248 {
249 /* We don't want to descend into the function parameters and
250 * dead-code eliminate them, so just accept the body here.
251 */
252 visit_list_elements(this, &ir->body);
253 return visit_continue_with_parent;
254 }
255