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    : 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
  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
  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
  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
  74 ir_array_refcount_entry::~ir_array_refcount_entry()
  75 {
  76    delete [] bits;
  77 }
  78
  79
  80 void
  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
  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 *
 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 *
 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
 163 ir_visitor_status
 164 ir_array_refcount_visitor::visit(ir_dereference_variable *ir)
 165 {
 166    ir_variable *const var = ir->variable_referenced();
 167    ir_array_refcount_entry *entry = this->get_variable_entry(var);
 168
 169    entry->is_referenced = true;
 170
 171    return visit_continue;
 172 }
 173
 174
 175 ir_visitor_status
 176 ir_array_refcount_visitor::visit_enter(ir_function_signature *ir)
 177 {
 178    /* We don't want to descend into the function parameters and
 179     * dead-code eliminate them, so just accept the body here.
 180     */
 181    visit_list_elements(this, &ir->body);
 182    return visit_continue_with_parent;
 183 }