src/glsl/ir_structure_splitting.cpp

   1 /*
   2  * Copyright © 2010 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_structure_splitting.cpp
  26  *
  27  * If a structure is only ever referenced by its components, then
  28  * split those components out to individual variables so they can be
  29  * handled normally by other optimization passes.
  30  *
  31  * This skips structures like uniforms, which need to be accessible as
  32  * structures for their access by the GL.
  33  */
  34
  35 #include "ir.h"
  36 #include "ir_visitor.h"
  37 #include "ir_print_visitor.h"
  38 #include "ir_rvalue_visitor.h"
  39 #include "glsl_types.h"
  40
  41 static bool debug = false;
  42
  43 class variable_entry : public exec_node
  44 {
  45 public:
  46    variable_entry(ir_variable *var)
  47    {
  48       this->var = var;
  49       this->whole_structure_access = 0;
  50       this->declaration = false;
  51       this->components = NULL;
  52       this->mem_ctx = NULL;
  53    }
  54
  55    ir_variable *var; /* The key: the variable's pointer. */
  56
  57    /** Number of times the variable is referenced, including assignments. */
  58    unsigned whole_structure_access;
  59
  60    bool declaration; /* If the variable had a decl in the instruction stream */
  61
  62    ir_variable **components;
  63
  64    /** talloc_parent(this->var) -- the shader's talloc context. */
  65    void *mem_ctx;
  66 };
  67
  68 class ir_structure_reference_visitor : public ir_hierarchical_visitor {
  69 public:
  70    ir_structure_reference_visitor(void)
  71    {
  72       this->mem_ctx = talloc_new(NULL);
  73       this->variable_list.make_empty();
  74    }
  75
  76    ~ir_structure_reference_visitor(void)
  77    {
  78       talloc_free(mem_ctx);
  79    }
  80
  81    virtual ir_visitor_status visit(ir_variable *);
  82    virtual ir_visitor_status visit(ir_dereference_variable *);
  83    virtual ir_visitor_status visit_enter(ir_dereference_record *);
  84    virtual ir_visitor_status visit_enter(ir_assignment *);
  85    virtual ir_visitor_status visit_enter(ir_function_signature *);
  86
  87    variable_entry *get_variable_entry(ir_variable *var);
  88
  89    /* List of variable_entry */
  90    exec_list variable_list;
  91
  92    void *mem_ctx;
  93 };
  94
  95 variable_entry *
  96 ir_structure_reference_visitor::get_variable_entry(ir_variable *var)
  97 {
  98    assert(var);
  99
 100    if (!var->type->is_record() || var->mode == ir_var_uniform)
 101       return NULL;
 102
 103    foreach_iter(exec_list_iterator, iter, this->variable_list) {
 104       variable_entry *entry = (variable_entry *)iter.get();
 105       if (entry->var == var)
 106          return entry;
 107    }
 108
 109    variable_entry *entry = new(mem_ctx) variable_entry(var);
 110    this->variable_list.push_tail(entry);
 111    return entry;
 112 }
 113
 114
 115 ir_visitor_status
 116 ir_structure_reference_visitor::visit(ir_variable *ir)
 117 {
 118    variable_entry *entry = this->get_variable_entry(ir);
 119
 120    if (entry)
 121       entry->declaration = true;
 122
 123    return visit_continue;
 124 }
 125
 126 ir_visitor_status
 127 ir_structure_reference_visitor::visit(ir_dereference_variable *ir)
 128 {
 129    ir_variable *const var = ir->variable_referenced();
 130    variable_entry *entry = this->get_variable_entry(var);
 131
 132    if (entry)
 133       entry->whole_structure_access++;
 134
 135    return visit_continue;
 136 }
 137
 138 ir_visitor_status
 139 ir_structure_reference_visitor::visit_enter(ir_dereference_record *ir)
 140 {
 141    /* Don't descend into the ir_dereference_variable below. */
 142    return visit_continue_with_parent;
 143 }
 144
 145 ir_visitor_status
 146 ir_structure_reference_visitor::visit_enter(ir_assignment *ir)
 147 {
 148    if (ir->lhs->as_dereference_variable() &&
 149        ir->rhs->as_dereference_variable() &&
 150        !ir->condition) {
 151       /* We'll split copies of a structure to copies of components, so don't
 152        * descend to the ir_dereference_variables.
 153        */
 154       return visit_continue_with_parent;
 155    }
 156    return visit_continue;
 157 }
 158
 159 ir_visitor_status
 160 ir_structure_reference_visitor::visit_enter(ir_function_signature *ir)
 161 {
 162    /* We don't want to descend into the function parameters and
 163     * dead-code eliminate them, so just accept the body here.
 164     */
 165    visit_list_elements(this, &ir->body);
 166    return visit_continue_with_parent;
 167 }
 168
 169 class ir_structure_splitting_visitor : public ir_rvalue_visitor {
 170 public:
 171    ir_structure_splitting_visitor(exec_list *vars)
 172    {
 173       this->variable_list = vars;
 174    }
 175
 176    virtual ~ir_structure_splitting_visitor()
 177    {
 178    }
 179
 180    virtual ir_visitor_status visit_leave(ir_assignment *);
 181
 182    void split_deref(ir_dereference **deref);
 183    void handle_rvalue(ir_rvalue **rvalue);
 184    variable_entry *get_splitting_entry(ir_variable *var);
 185
 186    exec_list *variable_list;
 187    void *mem_ctx;
 188 };
 189
 190 variable_entry *
 191 ir_structure_splitting_visitor::get_splitting_entry(ir_variable *var)
 192 {
 193    assert(var);
 194
 195    if (!var->type->is_record())
 196       return NULL;
 197
 198    foreach_iter(exec_list_iterator, iter, *this->variable_list) {
 199       variable_entry *entry = (variable_entry *)iter.get();
 200       if (entry->var == var) {
 201          return entry;
 202       }
 203    }
 204
 205    return NULL;
 206 }
 207
 208 void
 209 ir_structure_splitting_visitor::split_deref(ir_dereference **deref)
 210 {
 211    if ((*deref)->ir_type != ir_type_dereference_record)
 212       return;
 213
 214    ir_dereference_record *deref_record = (ir_dereference_record *)*deref;
 215    ir_dereference_variable *deref_var = deref_record->record->as_dereference_variable();
 216    if (!deref_var)
 217       return;
 218
 219    variable_entry *entry = get_splitting_entry(deref_var->var);
 220    if (!entry)
 221       return;
 222
 223    unsigned int i;
 224    for (i = 0; i < entry->var->type->length; i++) {
 225       if (strcmp(deref_record->field,
 226                  entry->var->type->fields.structure[i].name) == 0)
 227          break;
 228    }
 229    assert(i != entry->var->type->length);
 230
 231    *deref = new(entry->mem_ctx) ir_dereference_variable(entry->components[i]);
 232 }
 233
 234 void
 235 ir_structure_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)
 236 {
 237    if (!*rvalue)
 238       return;
 239
 240    ir_dereference *deref = (*rvalue)->as_dereference();
 241
 242    if (!deref)
 243       return;
 244
 245    split_deref(&deref);
 246    *rvalue = deref;
 247 }
 248
 249 ir_visitor_status
 250 ir_structure_splitting_visitor::visit_leave(ir_assignment *ir)
 251 {
 252    ir_dereference_variable *lhs_deref = ir->lhs->as_dereference_variable();
 253    ir_dereference_variable *rhs_deref = ir->rhs->as_dereference_variable();
 254    variable_entry *lhs_entry = lhs_deref ? get_splitting_entry(lhs_deref->var) : NULL;
 255    variable_entry *rhs_entry = rhs_deref ? get_splitting_entry(rhs_deref->var) : NULL;
 256    const glsl_type *type = ir->rhs->type;
 257
 258    if ((lhs_entry || rhs_entry) && !ir->condition) {
 259       for (unsigned int i = 0; i < type->length; i++) {
 260          ir_dereference *new_lhs, *new_rhs;
 261          void *mem_ctx = lhs_entry ? lhs_entry->mem_ctx : rhs_entry->mem_ctx;
 262
 263          if (lhs_entry) {
 264             new_lhs = new(mem_ctx) ir_dereference_variable(lhs_entry->components[i]);
 265          } else {
 266             new_lhs = new(mem_ctx)
 267                ir_dereference_record(ir->lhs->clone(mem_ctx, NULL),
 268                                      type->fields.structure[i].name);
 269          }
 270
 271          if (rhs_entry) {
 272             new_rhs = new(mem_ctx) ir_dereference_variable(rhs_entry->components[i]);
 273          } else {
 274             new_rhs = new(mem_ctx)
 275                ir_dereference_record(ir->rhs->clone(mem_ctx, NULL),
 276                                      type->fields.structure[i].name);
 277          }
 278
 279          ir->insert_before(new(mem_ctx) ir_assignment(new_lhs,
 280                                                       new_rhs,
 281                                                       NULL));
 282       }
 283       ir->remove();
 284    } else {
 285       handle_rvalue(&ir->rhs);
 286       split_deref(&ir->lhs);
 287    }
 288
 289    handle_rvalue(&ir->condition);
 290
 291    return visit_continue;
 292 }
 293
 294 bool
 295 do_structure_splitting(exec_list *instructions)
 296 {
 297    ir_structure_reference_visitor refs;
 298
 299    visit_list_elements(&refs, instructions);
 300
 301    /* Trim out variables we can't split. */
 302    foreach_iter(exec_list_iterator, iter, refs.variable_list) {
 303       variable_entry *entry = (variable_entry *)iter.get();
 304
 305       if (debug) {
 306          printf("structure %s@%p: decl %d, whole_access %d\n",
 307                 entry->var->name, (void *) entry->var, entry->declaration,
 308                 entry->whole_structure_access);
 309       }
 310
 311       if (!entry->declaration || entry->whole_structure_access) {
 312          entry->remove();
 313       }
 314    }
 315
 316    if (refs.variable_list.is_empty())
 317       return false;
 318
 319    void *mem_ctx = talloc_new(NULL);
 320
 321    /* Replace the decls of the structures to be split with their split
 322     * components.
 323     */
 324    foreach_iter(exec_list_iterator, iter, refs.variable_list) {
 325       variable_entry *entry = (variable_entry *)iter.get();
 326       const struct glsl_type *type = entry->var->type;
 327
 328       entry->mem_ctx = talloc_parent(entry->var);
 329
 330       entry->components = talloc_array(mem_ctx,
 331                                        ir_variable *,
 332                                        type->length);
 333
 334       for (unsigned int i = 0; i < entry->var->type->length; i++) {
 335          const char *name = talloc_asprintf(mem_ctx, "%s_%s",
 336                                             entry->var->name,
 337                                             type->fields.structure[i].name);
 338
 339          entry->components[i] =
 340             new(entry->mem_ctx) ir_variable(type->fields.structure[i].type,
 341                                             name,
 342                                             ir_var_temporary);
 343          entry->var->insert_before(entry->components[i]);
 344       }
 345
 346       entry->var->remove();
 347    }
 348
 349    ir_structure_splitting_visitor split(&refs.variable_list);
 350    visit_list_elements(&split, instructions);
 351
 352    talloc_free(mem_ctx);
 353
 354    return true;
 355 }