source/glsl/optimize.cpp

   1 #include <msp/core/raii.h>
   2 #include <msp/strings/format.h>
   3 #include "optimize.h"
   4
   5 using namespace std;
   6
   7 namespace Msp {
   8 namespace GL {
   9 namespace SL {
  10
  11 InlineableFunctionLocator::InlineableFunctionLocator():
  12         current_function(0),
  13         return_count(0)
  14 { }
  15
  16 void InlineableFunctionLocator::visit(FunctionCall &call)
  17 {
  18         FunctionDeclaration *def = call.declaration;
  19         if(def)
  20                 def = def->definition;
  21
  22         if(def)
  23         {
  24                 unsigned &count = refcounts[def];
  25                 ++count;
  26                 /* Don't inline functions which are called more than once or are called
  27                 recursively. */
  28                 if(count>1 || def==current_function)
  29                         inlineable.erase(def);
  30         }
  31
  32         TraversingVisitor::visit(call);
  33 }
  34
  35 void InlineableFunctionLocator::visit(FunctionDeclaration &func)
  36 {
  37         unsigned &count = refcounts[func.definition];
  38         if(count<=1 && func.parameters.empty())
  39                 inlineable.insert(func.definition);
  40
  41         SetForScope<FunctionDeclaration *> set(current_function, &func);
  42         return_count = 0;
  43         TraversingVisitor::visit(func);
  44 }
  45
  46 void InlineableFunctionLocator::visit(Conditional &cond)
  47 {
  48         TraversingVisitor::visit(cond);
  49         inlineable.erase(current_function);
  50 }
  51
  52 void InlineableFunctionLocator::visit(Iteration &iter)
  53 {
  54         TraversingVisitor::visit(iter);
  55         inlineable.erase(current_function);
  56 }
  57
  58 void InlineableFunctionLocator::visit(Return &ret)
  59 {
  60         TraversingVisitor::visit(ret);
  61         if(return_count)
  62                 inlineable.erase(current_function);
  63         ++return_count;
  64 }
  65
  66
  67 InlineContentInjector::InlineContentInjector():
  68         source_func(0),
  69         remap_names(false),
  70         deps_only(false)
  71 { }
  72
  73 const string &InlineContentInjector::apply(Stage &stage, FunctionDeclaration &target_func, Block &tgt_blk, const NodeList<Statement>::iterator &ins_pt, FunctionDeclaration &src)
  74 {
  75         target_block = &tgt_blk;
  76         source_func = &src;
  77         for(NodeList<Statement>::iterator i=src.body.body.begin(); i!=src.body.body.end(); ++i)
  78         {
  79                 r_inlined_statement = 0;
  80                 (*i)->visit(*this);
  81                 if(!r_inlined_statement)
  82                         r_inlined_statement = (*i)->clone();
  83
  84                 SetFlag set_remap(remap_names);
  85                 r_inlined_statement->visit(*this);
  86                 tgt_blk.body.insert(ins_pt, r_inlined_statement);
  87         }
  88
  89         NodeReorderer().apply(stage, target_func, dependencies);
  90
  91         return r_result_name;
  92 }
  93
  94 string InlineContentInjector::create_unused_name(const string &base, bool always_prefix)
  95 {
  96         string result = base;
  97         if(always_prefix || target_block->variables.count(result))
  98                 result = format("_%s_%s", source_func->name, base);
  99         unsigned initial_size = result.size();
 100         for(unsigned i=1; target_block->variables.count(result); ++i)
 101         {
 102                 result.erase(initial_size);
 103                 result += format("_%d", i);
 104         }
 105         return result;
 106 }
 107
 108 void InlineContentInjector::visit(VariableReference &var)
 109 {
 110         if(remap_names)
 111         {
 112                 map<string, VariableDeclaration *>::const_iterator i = variable_map.find(var.name);
 113                 if(i!=variable_map.end())
 114                         var.name = i->second->name;
 115         }
 116         else if(var.declaration)
 117         {
 118                 SetFlag set_deps(deps_only);
 119                 dependencies.insert(var.declaration);
 120                 var.declaration->visit(*this);
 121         }
 122 }
 123
 124 void InlineContentInjector::visit(InterfaceBlockReference &iface)
 125 {
 126         if(!remap_names && iface.declaration)
 127         {
 128                 SetFlag set_deps(deps_only);
 129                 dependencies.insert(iface.declaration);
 130                 iface.declaration->visit(*this);
 131         }
 132 }
 133
 134 void InlineContentInjector::visit(FunctionCall &call)
 135 {
 136         if(!remap_names && call.declaration)
 137                 dependencies.insert(call.declaration);
 138         TraversingVisitor::visit(call);
 139 }
 140
 141 void InlineContentInjector::visit(VariableDeclaration &var)
 142 {
 143         TraversingVisitor::visit(var);
 144
 145         if(var.type_declaration)
 146         {
 147                 SetFlag set_deps(deps_only);
 148                 dependencies.insert(var.type_declaration);
 149                 var.type_declaration->visit(*this);
 150         }
 151
 152         if(!remap_names && !deps_only)
 153         {
 154                 RefPtr<VariableDeclaration> inlined_var = var.clone();
 155                 inlined_var->name = create_unused_name(var.name, false);
 156                 r_inlined_statement = inlined_var;
 157
 158                 variable_map[var.name] = inlined_var.get();
 159         }
 160 }
 161
 162 void InlineContentInjector::visit(Return &ret)
 163 {
 164         TraversingVisitor::visit(ret);
 165
 166         if(ret.expression)
 167         {
 168                 /* Create a new variable to hold the return value of the inlined
 169                 function. */
 170                 r_result_name = create_unused_name("return", true);
 171                 RefPtr<VariableDeclaration> var = new VariableDeclaration;
 172                 var->source = ret.source;
 173                 var->line = ret.line;
 174                 var->type = source_func->return_type;
 175                 var->name = r_result_name;
 176                 var->init_expression = ret.expression->clone();
 177                 r_inlined_statement = var;
 178         }
 179 }
 180
 181
 182 FunctionInliner::FunctionInliner():
 183         current_function(0),
 184         r_any_inlined(false)
 185 { }
 186
 187 bool FunctionInliner::apply(Stage &s)
 188 {
 189         stage = &s;
 190         inlineable = InlineableFunctionLocator().apply(s);
 191         r_any_inlined = false;
 192         s.content.visit(*this);
 193         return r_any_inlined;
 194 }
 195
 196 void FunctionInliner::visit_and_inline(RefPtr<Expression> &ptr)
 197 {
 198         r_inline_result = 0;
 199         ptr->visit(*this);
 200         if(r_inline_result)
 201         {
 202                 ptr = r_inline_result;
 203                 r_any_inlined = true;
 204         }
 205 }
 206
 207 void FunctionInliner::visit(Block &block)
 208 {
 209         SetForScope<Block *> set_block(current_block, &block);
 210         SetForScope<NodeList<Statement>::iterator> save_insert_point(insert_point, block.body.begin());
 211         for(NodeList<Statement>::iterator i=block.body.begin(); i!=block.body.end(); ++i)
 212         {
 213                 insert_point = i;
 214                 (*i)->visit(*this);
 215         }
 216 }
 217
 218 void FunctionInliner::visit(UnaryExpression &unary)
 219 {
 220         visit_and_inline(unary.expression);
 221         r_inline_result = 0;
 222 }
 223
 224 void FunctionInliner::visit(BinaryExpression &binary)
 225 {
 226         visit_and_inline(binary.left);
 227         visit_and_inline(binary.right);
 228         r_inline_result = 0;
 229 }
 230
 231 void FunctionInliner::visit(MemberAccess &memacc)
 232 {
 233         visit_and_inline(memacc.left);
 234         r_inline_result = 0;
 235 }
 236
 237 void FunctionInliner::visit(FunctionCall &call)
 238 {
 239         for(NodeArray<Expression>::iterator i=call.arguments.begin(); i!=call.arguments.end(); ++i)
 240                 visit_and_inline(*i);
 241
 242         FunctionDeclaration *def = call.declaration;
 243         if(def)
 244                 def = def->definition;
 245
 246         if(def && inlineable.count(def))
 247         {
 248                 string result_name = InlineContentInjector().apply(*stage, *current_function, *current_block, insert_point, *def);
 249
 250                 // This will later get removed by UnusedVariableRemover.
 251                 if(result_name.empty())
 252                         result_name = "msp_unused_from_inline";
 253
 254                 RefPtr<VariableReference> ref = new VariableReference;
 255                 ref->name = result_name;
 256                 r_inline_result = ref;
 257
 258                 /* Inlined variables need to be resolved before this function can be
 259                 inlined further. */
 260                 inlineable.erase(current_function);
 261         }
 262         else
 263                 r_inline_result = 0;
 264 }
 265
 266 void FunctionInliner::visit(ExpressionStatement &expr)
 267 {
 268         visit_and_inline(expr.expression);
 269 }
 270
 271 void FunctionInliner::visit(VariableDeclaration &var)
 272 {
 273         if(var.init_expression)
 274                 visit_and_inline(var.init_expression);
 275         r_inline_result = 0;
 276 }
 277
 278 void FunctionInliner::visit(FunctionDeclaration &func)
 279 {
 280         SetForScope<FunctionDeclaration *> set_func(current_function, &func);
 281         TraversingVisitor::visit(func);
 282 }
 283
 284 void FunctionInliner::visit(Conditional &cond)
 285 {
 286         visit_and_inline(cond.condition);
 287         cond.body.visit(*this);
 288 }
 289
 290 void FunctionInliner::visit(Iteration &iter)
 291 {
 292         /* Visit the initialization statement before entering the loop body so the
 293         inlined statements get inserted outside. */
 294         if(iter.init_statement)
 295                 iter.init_statement->visit(*this);
 296
 297         SetForScope<Block *> set_block(current_block, &iter.body);
 298         /* Skip the condition and loop expression parts because they're not properly
 299         inside the body block.  Inlining anything into them will require a more
 300         comprehensive transformation. */
 301         iter.body.visit(*this);
 302 }
 303
 304 void FunctionInliner::visit(Return &ret)
 305 {
 306         if(ret.expression)
 307                 visit_and_inline(ret.expression);
 308 }
 309
 310
 311 ExpressionInliner::ExpressionInfo::ExpressionInfo():
 312         expression(0),
 313         assign_scope(0),
 314         inline_point(0),
 315         inner_oper(0),
 316         outer_oper(0),
 317         inline_on_rhs(false),
 318         trivial(false),
 319         available(true)
 320 { }
 321
 322
 323 ExpressionInliner::ExpressionInliner():
 324         r_ref_info(0),
 325         r_any_inlined(false),
 326         r_trivial(false),
 327         mutating(false),
 328         iteration_init(false),
 329         iteration_body(0),
 330         r_oper(0)
 331 { }
 332
 333 bool ExpressionInliner::apply(Stage &s)
 334 {
 335         s.content.visit(*this);
 336         return r_any_inlined;
 337 }
 338
 339 void ExpressionInliner::visit_and_record(RefPtr<Expression> &ptr, const Operator *outer_oper, bool on_rhs)
 340 {
 341         r_ref_info = 0;
 342         ptr->visit(*this);
 343         if(r_ref_info && r_ref_info->expression && r_ref_info->available)
 344         {
 345                 if(iteration_body && !r_ref_info->trivial)
 346                 {
 347                         /* Don't inline non-trivial expressions which were assigned outside
 348                         an iteration statement.  The iteration may run multiple times, which
 349                         would cause the expression to also be evaluated multiple times. */
 350                         Block *i = r_ref_info->assign_scope;
 351                         for(; (i && i!=iteration_body); i=i->parent) ;
 352                         if(!i)
 353                                 return;
 354                 }
 355
 356                 r_ref_info->outer_oper = outer_oper;
 357                 if(r_ref_info->trivial)
 358                         inline_expression(*r_ref_info->expression, ptr, outer_oper, r_ref_info->inner_oper, on_rhs);
 359                 else
 360                 {
 361                         /* Record the inline point for a non-trivial expression but don't
 362                         inline it yet.  It might turn out it shouldn't be inlined after all. */
 363                         r_ref_info->inline_point = &ptr;
 364                         r_ref_info->inline_on_rhs = on_rhs;
 365                 }
 366         }
 367 }
 368
 369 void ExpressionInliner::inline_expression(Expression &expr, RefPtr<Expression> &ptr, const Operator *outer_oper, const Operator *inner_oper, bool on_rhs)
 370 {
 371         unsigned outer_precedence = (outer_oper ? outer_oper->precedence : 20);
 372         unsigned inner_precedence = (inner_oper ? inner_oper->precedence : 0);
 373
 374         bool needs_parentheses = (inner_precedence>=outer_precedence);
 375         if(inner_oper && inner_oper==outer_oper)
 376                 // Omit parentheses if the operator's natural grouping works out.
 377                 needs_parentheses = (inner_oper->assoc!=Operator::ASSOCIATIVE && on_rhs!=(inner_oper->assoc==Operator::RIGHT_TO_LEFT));
 378
 379         if(needs_parentheses)
 380         {
 381                 RefPtr<ParenthesizedExpression> parexpr = new ParenthesizedExpression;
 382                 parexpr->expression = expr.clone();
 383                 ptr = parexpr;
 384         }
 385         else
 386                 ptr = expr.clone();
 387
 388         r_any_inlined = true;
 389 }
 390
 391 void ExpressionInliner::visit(Block &block)
 392 {
 393         TraversingVisitor::visit(block);
 394
 395         for(map<VariableDeclaration *, ExpressionInfo>::iterator i=expressions.begin(); i!=expressions.end(); )
 396         {
 397                 map<string, VariableDeclaration *>::iterator j = block.variables.find(i->first->name);
 398                 if(j!=block.variables.end() && j->second==i->first)
 399                 {
 400                         if(i->second.expression && i->second.inline_point)
 401                                 inline_expression(*i->second.expression, *i->second.inline_point, i->second.outer_oper, i->second.inner_oper, i->second.inline_on_rhs);
 402
 403                         expressions.erase(i++);
 404                 }
 405                 else
 406                 {
 407                         /* The expression was assigned in this block and may depend on local
 408                         variables of the block.  If this is a conditionally executed block,
 409                         the assignment might not always happen.  Mark the expression as not
 410                         available to any outer blocks. */
 411                         if(i->second.assign_scope==&block)
 412                                 i->second.available = false;
 413
 414                         ++i;
 415                 }
 416         }
 417 }
 418
 419 void ExpressionInliner::visit(VariableReference &var)
 420 {
 421         if(var.declaration)
 422         {
 423                 map<VariableDeclaration *, ExpressionInfo>::iterator i = expressions.find(var.declaration);
 424                 if(i!=expressions.end())
 425                 {
 426                         /* If a non-trivial expression is referenced multiple times, don't
 427                         inline it. */
 428                         if(i->second.inline_point && !i->second.trivial)
 429                                 i->second.expression = 0;
 430                         /* Mutating expressions are analogous to self-referencing assignments
 431                         and prevent inlining. */
 432                         if(mutating)
 433                                 i->second.expression = 0;
 434                         r_ref_info = &i->second;
 435                 }
 436         }
 437 }
 438
 439 void ExpressionInliner::visit(MemberAccess &memacc)
 440 {
 441         visit_and_record(memacc.left, memacc.oper, false);
 442         r_ref_info = 0;
 443         r_oper = memacc.oper;
 444         r_trivial = false;
 445 }
 446
 447 void ExpressionInliner::visit(UnaryExpression &unary)
 448 {
 449         SetFlag set_target(mutating, mutating || unary.oper->token[1]=='+' || unary.oper->token[1]=='-');
 450         visit_and_record(unary.expression, unary.oper, false);
 451         r_ref_info = 0;
 452         r_oper = unary.oper;
 453         r_trivial = false;
 454 }
 455
 456 void ExpressionInliner::visit(BinaryExpression &binary)
 457 {
 458         visit_and_record(binary.left, binary.oper, false);
 459         {
 460                 SetFlag clear_target(mutating, false);
 461                 visit_and_record(binary.right, binary.oper, true);
 462         }
 463         r_ref_info = 0;
 464         r_oper = binary.oper;
 465         r_trivial = false;
 466 }
 467
 468 void ExpressionInliner::visit(Assignment &assign)
 469 {
 470         {
 471                 SetFlag set_target(mutating);
 472                 visit_and_record(assign.left, assign.oper, false);
 473         }
 474         r_oper = 0;
 475         visit_and_record(assign.right, assign.oper, true);
 476
 477         if(assign.target_declaration)
 478         {
 479                 map<VariableDeclaration *, ExpressionInfo>::iterator i = expressions.find(assign.target_declaration);
 480                 if(i!=expressions.end())
 481                 {
 482                         /* Self-referencing assignments can't be inlined without additional
 483                         work.  Just clear any previous expression. */
 484                         i->second.expression = (assign.self_referencing ? 0 : assign.right.get());
 485                         i->second.assign_scope = current_block;
 486                         i->second.inline_point = 0;
 487                         i->second.inner_oper = r_oper;
 488                         i->second.available = true;
 489                 }
 490         }
 491
 492         r_ref_info = 0;
 493         r_oper = assign.oper;
 494         r_trivial = false;
 495 }
 496
 497 void ExpressionInliner::visit(FunctionCall &call)
 498 {
 499         for(NodeArray<Expression>::iterator i=call.arguments.begin(); i!=call.arguments.end(); ++i)
 500                 visit_and_record(*i, 0, false);
 501         r_ref_info = 0;
 502         r_oper = 0;
 503         r_trivial = false;
 504 }
 505
 506 void ExpressionInliner::visit(VariableDeclaration &var)
 507 {
 508         r_oper = 0;
 509         r_trivial = true;
 510         if(var.init_expression)
 511                 visit_and_record(var.init_expression, 0, false);
 512
 513         bool constant = var.constant;
 514         if(constant && var.layout)
 515         {
 516                 for(vector<Layout::Qualifier>::const_iterator i=var.layout->qualifiers.begin(); (constant && i!=var.layout->qualifiers.end()); ++i)
 517                         constant = (i->name!="constant_id");
 518         }
 519
 520         /* Only inline global variables if they're constant and have trivial
 521         initializers.  Non-constant variables could change in ways which are hard to
 522         analyze and non-trivial expressions could be expensive to inline.  */
 523         if((current_block->parent || (constant && r_trivial)) && var.interface.empty())
 524         {
 525                 ExpressionInfo &info = expressions[&var];
 526                 /* Assume variables declared in an iteration initialization statement
 527                 will have their values change throughout the iteration. */
 528                 info.expression = (iteration_init ? 0 : var.init_expression.get());
 529                 info.assign_scope = current_block;
 530                 info.inner_oper = r_oper;
 531                 info.trivial = r_trivial;
 532         }
 533 }
 534
 535 void ExpressionInliner::visit(Conditional &cond)
 536 {
 537         visit_and_record(cond.condition, 0, false);
 538         cond.body.visit(*this);
 539 }
 540
 541 void ExpressionInliner::visit(Iteration &iter)
 542 {
 543         SetForScope<Block *> set_block(current_block, &iter.body);
 544         if(iter.init_statement)
 545         {
 546                 SetFlag set_init(iteration_init);
 547                 iter.init_statement->visit(*this);
 548         }
 549
 550         SetForScope<Block *> set_body(iteration_body, &iter.body);
 551         if(iter.condition)
 552                 iter.condition->visit(*this);
 553         iter.body.visit(*this);
 554         if(iter.loop_expression)
 555                 iter.loop_expression->visit(*this);
 556 }
 557
 558 void ExpressionInliner::visit(Return &ret)
 559 {
 560         if(ret.expression)
 561                 visit_and_record(ret.expression, 0, false);
 562 }
 563
 564
 565 void ConstantConditionEliminator::apply(Stage &stage)
 566 {
 567         stage.content.visit(*this);
 568         NodeRemover().apply(stage, nodes_to_remove);
 569 }
 570
 571 void ConstantConditionEliminator::visit(Block &block)
 572 {
 573         SetForScope<Block *> set_block(current_block, &block);
 574         for(NodeList<Statement>::iterator i=block.body.begin(); i!=block.body.end(); ++i)
 575         {
 576                 insert_point = i;
 577                 (*i)->visit(*this);
 578         }
 579 }
 580
 581 void ConstantConditionEliminator::visit(Conditional &cond)
 582 {
 583         ExpressionEvaluator eval;
 584         cond.condition->visit(eval);
 585         if(eval.is_result_valid())
 586         {
 587                 Block &block = (eval.get_result() ? cond.body : cond.else_body);
 588                 current_block->body.splice(insert_point, block.body);
 589                 nodes_to_remove.insert(&cond);
 590                 return;
 591         }
 592
 593         TraversingVisitor::visit(cond);
 594 }
 595
 596 void ConstantConditionEliminator::visit(Iteration &iter)
 597 {
 598         if(iter.condition)
 599         {
 600                 /* If the loop condition is always false on the first iteration, the
 601                 entire loop can be removed */
 602                 ExpressionEvaluator::ValueMap values;
 603                 if(VariableDeclaration *var = dynamic_cast<VariableDeclaration *>(iter.init_statement.get()))
 604                         values[var] = var->init_expression.get();
 605                 ExpressionEvaluator eval(values);
 606                 iter.condition->visit(eval);
 607                 if(eval.is_result_valid() && !eval.get_result())
 608                 {
 609                         nodes_to_remove.insert(&iter);
 610                         return;
 611                 }
 612         }
 613
 614         TraversingVisitor::visit(iter);
 615 }
 616
 617
 618 UnusedVariableRemover::VariableInfo::VariableInfo():
 619         local(false),
 620         conditionally_assigned(false),
 621         referenced(false)
 622 { }
 623
 624
 625 UnusedVariableRemover::UnusedVariableRemover():
 626         aggregate(0),
 627         r_assignment(0),
 628         assignment_target(false),
 629         r_assign_to_subfield(false),
 630         r_side_effects(false)
 631 { }
 632
 633 bool UnusedVariableRemover::apply(Stage &stage)
 634 {
 635         variables.push_back(BlockVariableMap());
 636         stage.content.visit(*this);
 637         BlockVariableMap &global_variables = variables.back();
 638         for(BlockVariableMap::iterator i=global_variables.begin(); i!=global_variables.end(); ++i)
 639         {
 640                 /* Don't remove output variables which are used by the next stage or the
 641                 graphics API. */
 642                 if(i->first->interface=="out" && (stage.type==Stage::FRAGMENT || i->first->linked_declaration || !i->first->name.compare(0, 3, "gl_")))
 643                         continue;
 644
 645                 // Mark other unreferenced global variables as unused.
 646                 if(!i->second.referenced)
 647                 {
 648                         unused_nodes.insert(i->first);
 649                         clear_assignments(i->second, true);
 650                 }
 651         }
 652         variables.pop_back();
 653
 654         NodeRemover().apply(stage, unused_nodes);
 655
 656         return !unused_nodes.empty();
 657 }
 658
 659 void UnusedVariableRemover::visit(VariableReference &var)
 660 {
 661         map<VariableDeclaration *, Node *>::iterator i = aggregates.find(var.declaration);
 662         if(i!=aggregates.end())
 663                 unused_nodes.erase(i->second);
 664
 665         if(var.declaration && !assignment_target)
 666         {
 667                 VariableInfo &var_info = variables.back()[var.declaration];
 668                 // Previous assignments are used by this reference.
 669                 clear_assignments(var_info, false);
 670                 var_info.referenced = true;
 671         }
 672 }
 673
 674 void UnusedVariableRemover::visit(InterfaceBlockReference &iface)
 675 {
 676         unused_nodes.erase(iface.declaration);
 677 }
 678
 679 void UnusedVariableRemover::visit(MemberAccess &memacc)
 680 {
 681         r_assign_to_subfield = true;
 682         TraversingVisitor::visit(memacc);
 683         unused_nodes.erase(memacc.declaration);
 684 }
 685
 686 void UnusedVariableRemover::visit(UnaryExpression &unary)
 687 {
 688         TraversingVisitor::visit(unary);
 689         if(unary.oper->token[1]=='+' || unary.oper->token[1]=='-')
 690                 r_side_effects = true;
 691 }
 692
 693 void UnusedVariableRemover::visit(BinaryExpression &binary)
 694 {
 695         if(binary.oper->token[0]=='[')
 696         {
 697                 if(assignment_target)
 698                         r_assign_to_subfield = true;
 699                 binary.left->visit(*this);
 700                 SetFlag set(assignment_target, false);
 701                 binary.right->visit(*this);
 702         }
 703         else
 704                 TraversingVisitor::visit(binary);
 705 }
 706
 707 void UnusedVariableRemover::visit(Assignment &assign)
 708 {
 709         {
 710                 SetFlag set(assignment_target, !assign.self_referencing);
 711                 assign.left->visit(*this);
 712         }
 713         assign.right->visit(*this);
 714         r_assignment = &assign;
 715         r_side_effects = true;
 716 }
 717
 718 void UnusedVariableRemover::visit(FunctionCall &call)
 719 {
 720         TraversingVisitor::visit(call);
 721         /* Treat function calls as having side effects so expression statements
 722         consisting of nothing but a function call won't be optimized away. */
 723         r_side_effects = true;
 724 }
 725
 726 void UnusedVariableRemover::record_assignment(VariableDeclaration &var, Node &node, bool chained)
 727 {
 728         VariableInfo &var_info = variables.back()[&var];
 729         /* An assignment which completely replaces the value of the variable causes
 730         any previous unreferenced assignments to be unused. */
 731         if(!chained)
 732                 clear_assignments(var_info, true);
 733         var_info.assignments.push_back(&node);
 734         var_info.conditionally_assigned = false;
 735 }
 736
 737 void UnusedVariableRemover::clear_assignments(VariableInfo &var_info, bool mark_unused)
 738 {
 739         if(mark_unused)
 740         {
 741                 for(vector<Node *>::iterator i=var_info.assignments.begin(); i!=var_info.assignments.end(); ++i)
 742                         unused_nodes.insert(*i);
 743         }
 744         var_info.assignments.clear();
 745 }
 746
 747 void UnusedVariableRemover::visit(ExpressionStatement &expr)
 748 {
 749         r_assignment = 0;
 750         r_assign_to_subfield = false;
 751         r_side_effects = false;
 752         TraversingVisitor::visit(expr);
 753         if(r_assignment && r_assignment->target_declaration)
 754                 record_assignment(*r_assignment->target_declaration, expr, (r_assignment->self_referencing || r_assign_to_subfield));
 755         if(!r_side_effects)
 756                 unused_nodes.insert(&expr);
 757 }
 758
 759 void UnusedVariableRemover::visit(StructDeclaration &strct)
 760 {
 761         SetForScope<Node *> set(aggregate, &strct);
 762         unused_nodes.insert(&strct);
 763         TraversingVisitor::visit(strct);
 764 }
 765
 766 void UnusedVariableRemover::visit(VariableDeclaration &var)
 767 {
 768         if(aggregate)
 769                 aggregates[&var] = aggregate;
 770         else
 771         {
 772                 variables.back()[&var].local = true;
 773                 if(var.init_expression)
 774                         record_assignment(var, *var.init_expression, false);
 775         }
 776         unused_nodes.erase(var.type_declaration);
 777         TraversingVisitor::visit(var);
 778 }
 779
 780 void UnusedVariableRemover::visit(InterfaceBlock &iface)
 781 {
 782         SetForScope<Node *> set(aggregate, &iface);
 783         unused_nodes.insert(&iface);
 784         TraversingVisitor::visit(iface);
 785 }
 786
 787 void UnusedVariableRemover::visit(FunctionDeclaration &func)
 788 {
 789         variables.push_back(BlockVariableMap());
 790
 791         for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
 792                 (*i)->visit(*this);
 793         func.body.visit(*this);
 794
 795         BlockVariableMap &block_variables = variables.back();
 796
 797         /* Mark global variables as conditionally assigned so assignments in other
 798         functions won't be removed. */
 799         for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
 800                 if(!i->second.local)
 801                         i->second.conditionally_assigned = true;
 802
 803         /* Always treat function parameters as referenced.  Removing unused
 804         parameters is not currently supported. */
 805         for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
 806                 block_variables[i->get()].referenced = true;
 807
 808         merge_down_variables();
 809 }
 810
 811 void UnusedVariableRemover::merge_down_variables()
 812 {
 813         BlockVariableMap &parent_variables = variables[variables.size()-2];
 814         BlockVariableMap &block_variables = variables.back();
 815         for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
 816         {
 817                 if(i->second.local)
 818                 {
 819                         if(!i->second.referenced)
 820                                 unused_nodes.insert(i->first);
 821                         /* Any unreferenced assignments when a variable runs out of scope
 822                         become unused. */
 823                         clear_assignments(i->second, true);
 824                         continue;
 825                 }
 826
 827                 BlockVariableMap::iterator j = parent_variables.find(i->first);
 828                 if(j==parent_variables.end())
 829                         parent_variables.insert(*i);
 830                 else
 831                 {
 832                         // Merge a non-local variable's state into the parent scope.
 833                         if(i->second.referenced || !i->second.conditionally_assigned)
 834                                 clear_assignments(j->second, !i->second.referenced);
 835                         j->second.conditionally_assigned = i->second.conditionally_assigned;
 836                         j->second.referenced |= i->second.referenced;
 837                         j->second.assignments.insert(j->second.assignments.end(), i->second.assignments.begin(), i->second.assignments.end());
 838                 }
 839         }
 840         variables.pop_back();
 841 }
 842
 843 void UnusedVariableRemover::visit(Conditional &cond)
 844 {
 845         cond.condition->visit(*this);
 846         variables.push_back(BlockVariableMap());
 847         cond.body.visit(*this);
 848
 849         BlockVariableMap if_variables;
 850         swap(variables.back(), if_variables);
 851         cond.else_body.visit(*this);
 852
 853         // Combine variables from both branches.
 854         BlockVariableMap &else_variables = variables.back();
 855         for(BlockVariableMap::iterator i=else_variables.begin(); i!=else_variables.end(); ++i)
 856         {
 857                 BlockVariableMap::iterator j = if_variables.find(i->first);
 858                 if(j!=if_variables.end())
 859                 {
 860                         // The variable was found in both branches.
 861                         i->second.assignments.insert(i->second.assignments.end(), j->second.assignments.begin(), j->second.assignments.end());
 862                         i->second.conditionally_assigned |= j->second.conditionally_assigned;
 863                         if_variables.erase(j);
 864                 }
 865                 else
 866                         // Mark variables found in only one branch as conditionally assigned.
 867                         i->second.conditionally_assigned = true;
 868         }
 869
 870         /* Move variables which were only used in the if block into the combined
 871         block. */
 872         for(BlockVariableMap::iterator i=if_variables.begin(); i!=if_variables.end(); ++i)
 873         {
 874                 i->second.conditionally_assigned = true;
 875                 else_variables.insert(*i);
 876         }
 877
 878         merge_down_variables();
 879 }
 880
 881 void UnusedVariableRemover::visit(Iteration &iter)
 882 {
 883         variables.push_back(BlockVariableMap());
 884         TraversingVisitor::visit(iter);
 885         merge_down_variables();
 886 }
 887
 888
 889 bool UnusedFunctionRemover::apply(Stage &stage)
 890 {
 891         stage.content.visit(*this);
 892         NodeRemover().apply(stage, unused_nodes);
 893         return !unused_nodes.empty();
 894 }
 895
 896 void UnusedFunctionRemover::visit(FunctionCall &call)
 897 {
 898         TraversingVisitor::visit(call);
 899
 900         unused_nodes.erase(call.declaration);
 901         if(call.declaration && call.declaration->definition!=call.declaration)
 902                 used_definitions.insert(call.declaration->definition);
 903 }
 904
 905 void UnusedFunctionRemover::visit(FunctionDeclaration &func)
 906 {
 907         TraversingVisitor::visit(func);
 908
 909         if((func.name!="main" || func.body.body.empty()) && !used_definitions.count(&func))
 910                 unused_nodes.insert(&func);
 911 }
 912
 913 } // namespace SL
 914 } // namespace GL
 915 } // namespace Msp