src/compiler/glsl/ir_array_refcount.cpp

   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
  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_pointer_hash_table_create(NULL);
  41 }
  42
  43 static void
  44 free_entry(struct hash_entry *entry)
  45 {
  46    ir_array_refcount_entry *ivre = (ir_array_refcount_entry *) entry->data;
  47    delete ivre;
  48 }
  49
  50 ir_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
  56 ir_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
  73 ir_array_refcount_entry::~ir_array_refcount_entry()
  74 {
  75    delete [] bits;
  76 }
  77
  78 ir_array_refcount_entry *
  79 ir_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
  94 array_deref_range *
  95 ir_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
 113 ir_visitor_status
 114 ir_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
 187 ir_visitor_status
 188 ir_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
 199 ir_visitor_status
 200 ir_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 }