src/glsl/opt_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 opt_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_rvalue_visitor.h"
  38 #include "glsl_types.h"
  39
  40 namespace {
  41
  42 static bool debug = false;
  43
  44 class variable_entry : public exec_node
  45 {
  46 public:
  47    variable_entry(ir_variable *var)
  48    {
  49       this->var = var;
  50       this->whole_structure_access = 0;
  51       this->declaration = false;
  52       this->components = NULL;
  53       this->mem_ctx = NULL;
  54    }
  55
  56    ir_variable *var; /* The key: the variable's pointer. */
  57
  58    /** Number of times the variable is referenced, including assignments. */
  59    unsigned whole_structure_access;
  60
  61    /* If the variable had a decl we can work with in the instruction
  62     * stream.  We can't do splitting on function arguments, which
  63     * don't get this variable set.
  64     */
  65    bool declaration;
  66
  67    ir_variable **components;
  68
  69    /** ralloc_parent(this->var) -- the shader's ralloc context. */
  70    void *mem_ctx;
  71 };
  72
  73
  74 class ir_structure_reference_visitor : public ir_hierarchical_visitor {
  75 public:
  76    ir_structure_reference_visitor(void)
  77    {
  78       this->mem_ctx = ralloc_context(NULL);
  79       this->variable_list.make_empty();
  80    }
  81
  82    ~ir_structure_reference_visitor(void)
  83    {
  84       ralloc_free(mem_ctx);
  85    }
  86
  87    virtual ir_visitor_status visit(ir_variable *);
  88    virtual ir_visitor_status visit(ir_dereference_variable *);
  89    virtual ir_visitor_status visit_enter(ir_dereference_record *);
  90    virtual ir_visitor_status visit_enter(ir_assignment *);
  91    virtual ir_visitor_status visit_enter(ir_function_signature *);
  92
  93    variable_entry *get_variable_entry(ir_variable *var);
  94
  95    /* List of variable_entry */
  96    exec_list variable_list;
  97
  98    void *mem_ctx;
  99 };
 100
 101 variable_entry *
 102 ir_structure_reference_visitor::get_variable_entry(ir_variable *var)
 103 {
 104    assert(var);
 105
 106    if (!var->type->is_record() || var->mode == ir_var_uniform
 107        || var->mode == ir_var_shader_in || var->mode == ir_var_shader_out)
 108       return NULL;
 109
 110    foreach_iter(exec_list_iterator, iter, this->variable_list) {
 111       variable_entry *entry = (variable_entry *)iter.get();
 112       if (entry->var == var)
 113          return entry;
 114    }
 115
 116    variable_entry *entry = new(mem_ctx) variable_entry(var);
 117    this->variable_list.push_tail(entry);
 118    return entry;
 119 }
 120
 121
 122 ir_visitor_status
 123 ir_structure_reference_visitor::visit(ir_variable *ir)
 124 {
 125    variable_entry *entry = this->get_variable_entry(ir);
 126
 127    if (entry)
 128       entry->declaration = true;
 129
 130    return visit_continue;
 131 }
 132
 133 ir_visitor_status
 134 ir_structure_reference_visitor::visit(ir_dereference_variable *ir)
 135 {
 136    ir_variable *const var = ir->variable_referenced();
 137    variable_entry *entry = this->get_variable_entry(var);
 138
 139    if (entry)
 140       entry->whole_structure_access++;
 141
 142    return visit_continue;
 143 }
 144
 145 ir_visitor_status
 146 ir_structure_reference_visitor::visit_enter(ir_dereference_record *ir)
 147 {
 148    (void) ir;
 149    /* Don't descend into the ir_dereference_variable below. */
 150    return visit_continue_with_parent;
 151 }
 152
 153 ir_visitor_status
 154 ir_structure_reference_visitor::visit_enter(ir_assignment *ir)
 155 {
 156    /* If there are no structure references yet, no need to bother with
 157     * processing the expression tree.
 158     */
 159    if (this->variable_list.is_empty())
 160       return visit_continue_with_parent;
 161
 162    if (ir->lhs->as_dereference_variable() &&
 163        ir->rhs->as_dereference_variable() &&
 164        !ir->condition) {
 165       /* We'll split copies of a structure to copies of components, so don't
 166        * descend to the ir_dereference_variables.
 167        */
 168       return visit_continue_with_parent;
 169    }
 170    return visit_continue;
 171 }
 172
 173 ir_visitor_status
 174 ir_structure_reference_visitor::visit_enter(ir_function_signature *ir)
 175 {
 176    /* We don't have logic for structure-splitting function arguments,
 177     * so just look at the body instructions and not the parameter
 178     * declarations.
 179     */
 180    visit_list_elements(this, &ir->body);
 181    return visit_continue_with_parent;
 182 }
 183
 184 class ir_structure_splitting_visitor : public ir_rvalue_visitor {
 185 public:
 186    ir_structure_splitting_visitor(exec_list *vars)
 187    {
 188       this->variable_list = vars;
 189    }
 190
 191    virtual ~ir_structure_splitting_visitor()
 192    {
 193    }
 194
 195    virtual ir_visitor_status visit_leave(ir_assignment *);
 196
 197    void split_deref(ir_dereference **deref);
 198    void handle_rvalue(ir_rvalue **rvalue);
 199    variable_entry *get_splitting_entry(ir_variable *var);
 200
 201    exec_list *variable_list;
 202 };
 203
 204 variable_entry *
 205 ir_structure_splitting_visitor::get_splitting_entry(ir_variable *var)
 206 {
 207    assert(var);
 208
 209    if (!var->type->is_record())
 210       return NULL;
 211
 212    foreach_iter(exec_list_iterator, iter, *this->variable_list) {
 213       variable_entry *entry = (variable_entry *)iter.get();
 214       if (entry->var == var) {
 215          return entry;
 216       }
 217    }
 218
 219    return NULL;
 220 }
 221
 222 void
 223 ir_structure_splitting_visitor::split_deref(ir_dereference **deref)
 224 {
 225    if ((*deref)->ir_type != ir_type_dereference_record)
 226       return;
 227
 228    ir_dereference_record *deref_record = (ir_dereference_record *)*deref;
 229    ir_dereference_variable *deref_var = deref_record->record->as_dereference_variable();
 230    if (!deref_var)
 231       return;
 232
 233    variable_entry *entry = get_splitting_entry(deref_var->var);
 234    if (!entry)
 235       return;
 236
 237    unsigned int i;
 238    for (i = 0; i < entry->var->type->length; i++) {
 239       if (strcmp(deref_record->field,
 240                  entry->var->type->fields.structure[i].name) == 0)
 241          break;
 242    }
 243    assert(i != entry->var->type->length);
 244
 245    *deref = new(entry->mem_ctx) ir_dereference_variable(entry->components[i]);
 246 }
 247
 248 void
 249 ir_structure_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)
 250 {
 251    if (!*rvalue)
 252       return;
 253
 254    ir_dereference *deref = (*rvalue)->as_dereference();
 255
 256    if (!deref)
 257       return;
 258
 259    split_deref(&deref);
 260    *rvalue = deref;
 261 }
 262
 263 ir_visitor_status
 264 ir_structure_splitting_visitor::visit_leave(ir_assignment *ir)
 265 {
 266    ir_dereference_variable *lhs_deref = ir->lhs->as_dereference_variable();
 267    ir_dereference_variable *rhs_deref = ir->rhs->as_dereference_variable();
 268    variable_entry *lhs_entry = lhs_deref ? get_splitting_entry(lhs_deref->var) : NULL;
 269    variable_entry *rhs_entry = rhs_deref ? get_splitting_entry(rhs_deref->var) : NULL;
 270    const glsl_type *type = ir->rhs->type;
 271
 272    if ((lhs_entry || rhs_entry) && !ir->condition) {
 273       for (unsigned int i = 0; i < type->length; i++) {
 274          ir_dereference *new_lhs, *new_rhs;
 275          void *mem_ctx = lhs_entry ? lhs_entry->mem_ctx : rhs_entry->mem_ctx;
 276
 277          if (lhs_entry) {
 278             new_lhs = new(mem_ctx) ir_dereference_variable(lhs_entry->components[i]);
 279          } else {
 280             new_lhs = new(mem_ctx)
 281                ir_dereference_record(ir->lhs->clone(mem_ctx, NULL),
 282                                      type->fields.structure[i].name);
 283          }
 284
 285          if (rhs_entry) {
 286             new_rhs = new(mem_ctx) ir_dereference_variable(rhs_entry->components[i]);
 287          } else {
 288             new_rhs = new(mem_ctx)
 289                ir_dereference_record(ir->rhs->clone(mem_ctx, NULL),
 290                                      type->fields.structure[i].name);
 291          }
 292
 293          ir->insert_before(new(mem_ctx) ir_assignment(new_lhs,
 294                                                       new_rhs,
 295                                                       NULL));
 296       }
 297       ir->remove();
 298    } else {
 299       handle_rvalue(&ir->rhs);
 300       split_deref(&ir->lhs);
 301    }
 302
 303    handle_rvalue(&ir->condition);
 304
 305    return visit_continue;
 306 }
 307
 308 } /* unnamed namespace */
 309
 310 bool
 311 do_structure_splitting(exec_list *instructions)
 312 {
 313    ir_structure_reference_visitor refs;
 314
 315    visit_list_elements(&refs, instructions);
 316
 317    /* Trim out variables we can't split. */
 318    foreach_iter(exec_list_iterator, iter, refs.variable_list) {
 319       variable_entry *entry = (variable_entry *)iter.get();
 320
 321       if (debug) {
 322          printf("structure %s@%p: decl %d, whole_access %d\n",
 323                 entry->var->name, (void *) entry->var, entry->declaration,
 324                 entry->whole_structure_access);
 325       }
 326
 327       if (!entry->declaration || entry->whole_structure_access) {
 328          entry->remove();
 329       }
 330    }
 331
 332    if (refs.variable_list.is_empty())
 333       return false;
 334
 335    void *mem_ctx = ralloc_context(NULL);
 336
 337    /* Replace the decls of the structures to be split with their split
 338     * components.
 339     */
 340    foreach_iter(exec_list_iterator, iter, refs.variable_list) {
 341       variable_entry *entry = (variable_entry *)iter.get();
 342       const struct glsl_type *type = entry->var->type;
 343
 344       entry->mem_ctx = ralloc_parent(entry->var);
 345
 346       entry->components = ralloc_array(mem_ctx,
 347                                        ir_variable *,
 348                                        type->length);
 349
 350       for (unsigned int i = 0; i < entry->var->type->length; i++) {
 351          const char *name = ralloc_asprintf(mem_ctx, "%s_%s",
 352                                             entry->var->name,
 353                                             type->fields.structure[i].name);
 354
 355          entry->components[i] =
 356             new(entry->mem_ctx) ir_variable(type->fields.structure[i].type,
 357                                             name,
 358                                             ir_var_temporary);
 359          entry->var->insert_before(entry->components[i]);
 360       }
 361
 362       entry->var->remove();
 363    }
 364
 365    ir_structure_splitting_visitor split(&refs.variable_list);
 366    visit_list_elements(&split, instructions);
 367
 368    ralloc_free(mem_ctx);
 369
 370    return true;
 371 }