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(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         r_inline_result = 0;
 206 }
 207
 208 void FunctionInliner::visit(Block &block)
 209 {
 210         SetForScope<Block *> set_block(current_block, &block);
 211         SetForScope<NodeList<Statement>::iterator> save_insert_point(insert_point, block.body.begin());
 212         for(NodeList<Statement>::iterator i=block.body.begin(); i!=block.body.end(); ++i)
 213         {
 214                 insert_point = i;
 215                 (*i)->visit(*this);
 216         }
 217 }
 218
 219 void FunctionInliner::visit(FunctionCall &call)
 220 {
 221         for(NodeArray<Expression>::iterator i=call.arguments.begin(); i!=call.arguments.end(); ++i)
 222                 visit(*i);
 223
 224         FunctionDeclaration *def = call.declaration;
 225         if(def)
 226                 def = def->definition;
 227
 228         if(def && inlineable.count(def))
 229         {
 230                 string result_name = InlineContentInjector().apply(*stage, *current_function, *current_block, insert_point, *def);
 231
 232                 // This will later get removed by UnusedVariableRemover.
 233                 if(result_name.empty())
 234                         result_name = "msp_unused_from_inline";
 235
 236                 RefPtr<VariableReference> ref = new VariableReference;
 237                 ref->name = result_name;
 238                 r_inline_result = ref;
 239
 240                 /* Inlined variables need to be resolved before this function can be
 241                 inlined further. */
 242                 inlineable.erase(current_function);
 243         }
 244 }
 245
 246 void FunctionInliner::visit(FunctionDeclaration &func)
 247 {
 248         SetForScope<FunctionDeclaration *> set_func(current_function, &func);
 249         TraversingVisitor::visit(func);
 250 }
 251
 252 void FunctionInliner::visit(Iteration &iter)
 253 {
 254         /* Visit the initialization statement before entering the loop body so the
 255         inlined statements get inserted outside. */
 256         if(iter.init_statement)
 257                 iter.init_statement->visit(*this);
 258
 259         SetForScope<Block *> set_block(current_block, &iter.body);
 260         /* Skip the condition and loop expression parts because they're not properly
 261         inside the body block.  Inlining anything into them will require a more
 262         comprehensive transformation. */
 263         iter.body.visit(*this);
 264 }
 265
 266
 267 ExpressionInliner::ExpressionInfo::ExpressionInfo():
 268         expression(0),
 269         assign_scope(0),
 270         inline_point(0),
 271         inner_oper(0),
 272         outer_oper(0),
 273         inline_on_rhs(false),
 274         trivial(false),
 275         available(true)
 276 { }
 277
 278
 279 ExpressionInliner::ExpressionInliner():
 280         r_ref_info(0),
 281         r_any_inlined(false),
 282         r_trivial(false),
 283         mutating(false),
 284         iteration_init(false),
 285         iteration_body(0),
 286         r_oper(0)
 287 { }
 288
 289 bool ExpressionInliner::apply(Stage &s)
 290 {
 291         s.content.visit(*this);
 292         return r_any_inlined;
 293 }
 294
 295 void ExpressionInliner::visit_and_record(RefPtr<Expression> &ptr, const Operator *outer_oper, bool on_rhs)
 296 {
 297         r_ref_info = 0;
 298         ptr->visit(*this);
 299         if(r_ref_info && r_ref_info->expression && r_ref_info->available)
 300         {
 301                 if(iteration_body && !r_ref_info->trivial)
 302                 {
 303                         /* Don't inline non-trivial expressions which were assigned outside
 304                         an iteration statement.  The iteration may run multiple times, which
 305                         would cause the expression to also be evaluated multiple times. */
 306                         Block *i = r_ref_info->assign_scope;
 307                         for(; (i && i!=iteration_body); i=i->parent) ;
 308                         if(!i)
 309                                 return;
 310                 }
 311
 312                 r_ref_info->outer_oper = outer_oper;
 313                 if(r_ref_info->trivial)
 314                         inline_expression(*r_ref_info->expression, ptr, outer_oper, r_ref_info->inner_oper, on_rhs);
 315                 else
 316                 {
 317                         /* Record the inline point for a non-trivial expression but don't
 318                         inline it yet.  It might turn out it shouldn't be inlined after all. */
 319                         r_ref_info->inline_point = &ptr;
 320                         r_ref_info->inline_on_rhs = on_rhs;
 321                 }
 322         }
 323         r_ref_info = 0;
 324 }
 325
 326 void ExpressionInliner::inline_expression(Expression &expr, RefPtr<Expression> &ptr, const Operator *outer_oper, const Operator *inner_oper, bool on_rhs)
 327 {
 328         unsigned outer_precedence = (outer_oper ? outer_oper->precedence : 20);
 329         unsigned inner_precedence = (inner_oper ? inner_oper->precedence : 0);
 330
 331         bool needs_parentheses = (inner_precedence>=outer_precedence);
 332         if(inner_oper && inner_oper==outer_oper)
 333                 // Omit parentheses if the operator's natural grouping works out.
 334                 needs_parentheses = (inner_oper->assoc!=Operator::ASSOCIATIVE && on_rhs!=(inner_oper->assoc==Operator::RIGHT_TO_LEFT));
 335
 336         if(needs_parentheses)
 337         {
 338                 RefPtr<ParenthesizedExpression> parexpr = new ParenthesizedExpression;
 339                 parexpr->expression = expr.clone();
 340                 ptr = parexpr;
 341         }
 342         else
 343                 ptr = expr.clone();
 344
 345         r_any_inlined = true;
 346 }
 347
 348 void ExpressionInliner::visit(Block &block)
 349 {
 350         TraversingVisitor::visit(block);
 351
 352         for(map<string, VariableDeclaration *>::iterator i=block.variables.begin(); i!=block.variables.end(); ++i)
 353         {
 354                 map<Assignment::Target, ExpressionInfo>::iterator j = expressions.lower_bound(i->second);
 355                 for(; (j!=expressions.end() && j->first.declaration==i->second); )
 356                 {
 357                         if(j->second.expression && j->second.inline_point)
 358                                 inline_expression(*j->second.expression, *j->second.inline_point, j->second.outer_oper, j->second.inner_oper, j->second.inline_on_rhs);
 359
 360                         expressions.erase(j++);
 361                 }
 362         }
 363
 364         /* Expressions assigned in this block may depend on local variables of the
 365         block.  If this is a conditionally executed block, the assignments might not
 366         always happen.  Mark the expressions as not available to any outer blocks. */
 367         for(map<Assignment::Target, ExpressionInfo>::iterator i=expressions.begin(); i!=expressions.end(); ++i)
 368                 if(i->second.assign_scope==&block)
 369                         i->second.available = false;
 370 }
 371
 372 void ExpressionInliner::visit(RefPtr<Expression> &expr)
 373 {
 374         visit_and_record(expr, 0, false);
 375 }
 376
 377 void ExpressionInliner::visit(VariableReference &var)
 378 {
 379         if(var.declaration)
 380         {
 381                 map<Assignment::Target, ExpressionInfo>::iterator i = expressions.find(var.declaration);
 382                 if(i!=expressions.end())
 383                 {
 384                         /* If a non-trivial expression is referenced multiple times, don't
 385                         inline it. */
 386                         if(i->second.inline_point && !i->second.trivial)
 387                                 i->second.expression = 0;
 388                         /* Mutating expressions are analogous to self-referencing assignments
 389                         and prevent inlining. */
 390                         if(mutating)
 391                                 i->second.expression = 0;
 392                         r_ref_info = &i->second;
 393                 }
 394         }
 395 }
 396
 397 void ExpressionInliner::visit(MemberAccess &memacc)
 398 {
 399         visit_and_record(memacc.left, memacc.oper, false);
 400         r_oper = memacc.oper;
 401         r_trivial = false;
 402 }
 403
 404 void ExpressionInliner::visit(Swizzle &swizzle)
 405 {
 406         visit_and_record(swizzle.left, swizzle.oper, false);
 407         r_oper = swizzle.oper;
 408         r_trivial = false;
 409 }
 410
 411 void ExpressionInliner::visit(UnaryExpression &unary)
 412 {
 413         SetFlag set_target(mutating, mutating || unary.oper->token[1]=='+' || unary.oper->token[1]=='-');
 414         visit_and_record(unary.expression, unary.oper, false);
 415         r_oper = unary.oper;
 416         r_trivial = false;
 417 }
 418
 419 void ExpressionInliner::visit(BinaryExpression &binary)
 420 {
 421         visit_and_record(binary.left, binary.oper, false);
 422         {
 423                 SetFlag clear_target(mutating, false);
 424                 visit_and_record(binary.right, binary.oper, true);
 425         }
 426         r_oper = binary.oper;
 427         r_trivial = false;
 428 }
 429
 430 void ExpressionInliner::visit(Assignment &assign)
 431 {
 432         {
 433                 SetFlag set_target(mutating);
 434                 visit_and_record(assign.left, assign.oper, false);
 435         }
 436         r_oper = 0;
 437         visit_and_record(assign.right, assign.oper, true);
 438
 439         map<Assignment::Target, ExpressionInfo>::iterator i = expressions.find(assign.target);
 440         if(i!=expressions.end())
 441         {
 442                 /* Self-referencing assignments can't be inlined without additional
 443                 work.  Just clear any previous expression. */
 444                 i->second.expression = (assign.self_referencing ? 0 : assign.right.get());
 445                 i->second.assign_scope = current_block;
 446                 i->second.inline_point = 0;
 447                 i->second.inner_oper = r_oper;
 448                 i->second.available = true;
 449         }
 450
 451         r_oper = assign.oper;
 452         r_trivial = false;
 453 }
 454
 455 void ExpressionInliner::visit(FunctionCall &call)
 456 {
 457         TraversingVisitor::visit(call);
 458         r_oper = 0;
 459         r_trivial = false;
 460 }
 461
 462 void ExpressionInliner::visit(VariableDeclaration &var)
 463 {
 464         r_oper = 0;
 465         r_trivial = true;
 466         TraversingVisitor::visit(var);
 467
 468         bool constant = var.constant;
 469         if(constant && var.layout)
 470         {
 471                 for(vector<Layout::Qualifier>::const_iterator i=var.layout->qualifiers.begin(); (constant && i!=var.layout->qualifiers.end()); ++i)
 472                         constant = (i->name!="constant_id");
 473         }
 474
 475         /* Only inline global variables if they're constant and have trivial
 476         initializers.  Non-constant variables could change in ways which are hard to
 477         analyze and non-trivial expressions could be expensive to inline.  */
 478         if((current_block->parent || (constant && r_trivial)) && var.interface.empty())
 479         {
 480                 ExpressionInfo &info = expressions[&var];
 481                 /* Assume variables declared in an iteration initialization statement
 482                 will have their values change throughout the iteration. */
 483                 info.expression = (iteration_init ? 0 : var.init_expression.get());
 484                 info.assign_scope = current_block;
 485                 info.inner_oper = r_oper;
 486                 info.trivial = r_trivial;
 487         }
 488 }
 489
 490 void ExpressionInliner::visit(Iteration &iter)
 491 {
 492         SetForScope<Block *> set_block(current_block, &iter.body);
 493         if(iter.init_statement)
 494         {
 495                 SetFlag set_init(iteration_init);
 496                 iter.init_statement->visit(*this);
 497         }
 498
 499         SetForScope<Block *> set_body(iteration_body, &iter.body);
 500         if(iter.condition)
 501                 visit(iter.condition);
 502         iter.body.visit(*this);
 503         if(iter.loop_expression)
 504                 visit(iter.loop_expression);
 505 }
 506
 507
 508 void ConstantConditionEliminator::apply(Stage &stage)
 509 {
 510         stage.content.visit(*this);
 511         NodeRemover().apply(stage, nodes_to_remove);
 512 }
 513
 514 void ConstantConditionEliminator::visit(Block &block)
 515 {
 516         SetForScope<Block *> set_block(current_block, &block);
 517         for(NodeList<Statement>::iterator i=block.body.begin(); i!=block.body.end(); ++i)
 518         {
 519                 insert_point = i;
 520                 (*i)->visit(*this);
 521         }
 522 }
 523
 524 void ConstantConditionEliminator::visit(Conditional &cond)
 525 {
 526         ExpressionEvaluator eval;
 527         cond.condition->visit(eval);
 528         if(eval.is_result_valid())
 529         {
 530                 Block &block = (eval.get_result() ? cond.body : cond.else_body);
 531                 current_block->body.splice(insert_point, block.body);
 532                 nodes_to_remove.insert(&cond);
 533                 return;
 534         }
 535
 536         TraversingVisitor::visit(cond);
 537 }
 538
 539 void ConstantConditionEliminator::visit(Iteration &iter)
 540 {
 541         if(iter.condition)
 542         {
 543                 /* If the loop condition is always false on the first iteration, the
 544                 entire loop can be removed */
 545                 ExpressionEvaluator::ValueMap values;
 546                 if(VariableDeclaration *var = dynamic_cast<VariableDeclaration *>(iter.init_statement.get()))
 547                         values[var] = var->init_expression.get();
 548                 ExpressionEvaluator eval(values);
 549                 iter.condition->visit(eval);
 550                 if(eval.is_result_valid() && !eval.get_result())
 551                 {
 552                         nodes_to_remove.insert(&iter);
 553                         return;
 554                 }
 555         }
 556
 557         TraversingVisitor::visit(iter);
 558 }
 559
 560
 561 bool UnusedTypeRemover::apply(Stage &stage)
 562 {
 563         stage.content.visit(*this);
 564         NodeRemover().apply(stage, unused_nodes);
 565         return !unused_nodes.empty();
 566 }
 567
 568 void UnusedTypeRemover::visit(Literal &literal)
 569 {
 570         unused_nodes.erase(literal.type);
 571 }
 572
 573 void UnusedTypeRemover::visit(UnaryExpression &unary)
 574 {
 575         unused_nodes.erase(unary.type);
 576         TraversingVisitor::visit(unary);
 577 }
 578
 579 void UnusedTypeRemover::visit(BinaryExpression &binary)
 580 {
 581         unused_nodes.erase(binary.type);
 582         TraversingVisitor::visit(binary);
 583 }
 584
 585 void UnusedTypeRemover::visit(FunctionCall &call)
 586 {
 587         unused_nodes.erase(call.type);
 588         TraversingVisitor::visit(call);
 589 }
 590
 591 void UnusedTypeRemover::visit(BasicTypeDeclaration &type)
 592 {
 593         if(type.base_type)
 594                 unused_nodes.erase(type.base_type);
 595         unused_nodes.insert(&type);
 596 }
 597
 598 void UnusedTypeRemover::visit(ImageTypeDeclaration &type)
 599 {
 600         if(type.base_type)
 601                 unused_nodes.erase(type.base_type);
 602         unused_nodes.insert(&type);
 603 }
 604
 605 void UnusedTypeRemover::visit(StructDeclaration &strct)
 606 {
 607         unused_nodes.insert(&strct);
 608         TraversingVisitor::visit(strct);
 609 }
 610
 611 void UnusedTypeRemover::visit(VariableDeclaration &var)
 612 {
 613         unused_nodes.erase(var.type_declaration);
 614 }
 615
 616 void UnusedTypeRemover::visit(InterfaceBlock &iface)
 617 {
 618         unused_nodes.erase(iface.type_declaration);
 619 }
 620
 621 void UnusedTypeRemover::visit(FunctionDeclaration &func)
 622 {
 623         unused_nodes.erase(func.return_type_declaration);
 624         TraversingVisitor::visit(func);
 625 }
 626
 627
 628 UnusedVariableRemover::VariableInfo::VariableInfo():
 629         local(false),
 630         output(false),
 631         conditionally_assigned(false),
 632         referenced(false),
 633         interface_block(0)
 634 { }
 635
 636
 637 UnusedVariableRemover::UnusedVariableRemover():
 638         stage(0),
 639         interface_block(0),
 640         r_assignment(0),
 641         assignment_target(false),
 642         r_side_effects(false)
 643 { }
 644
 645 bool UnusedVariableRemover::apply(Stage &s)
 646 {
 647         stage = &s;
 648         variables.push_back(BlockVariableMap());
 649         s.content.visit(*this);
 650
 651         BlockVariableMap &global_variables = variables.back();
 652         set<InterfaceBlock *> used_interface_blocks;
 653         Statement *prev_decl = 0;
 654         bool output;
 655         for(BlockVariableMap::iterator i=global_variables.begin(); i!=global_variables.end(); ++i)
 656         {
 657                 if(i->first.declaration!=prev_decl)
 658                 {
 659                         prev_decl = i->first.declaration;
 660                         output = i->second.output;
 661                 }
 662                 if(output)
 663                 {
 664                         if((i->second.referenced || !i->second.assignments.empty()) && i->second.interface_block)
 665                                 used_interface_blocks.insert(i->second.interface_block);
 666                         continue;
 667                 }
 668
 669                 // Mark other unreferenced global variables as unused.
 670                 if(!i->second.referenced)
 671                 {
 672                         if(!i->second.interface_block && !i->first.chain_len)
 673                                 unused_nodes.insert(i->first.declaration);
 674                         clear_assignments(i->second, true);
 675                 }
 676                 else if(i->second.interface_block)
 677                         used_interface_blocks.insert(i->second.interface_block);
 678         }
 679         variables.pop_back();
 680
 681         for(map<string, InterfaceBlock *>::const_iterator i=s.interface_blocks.begin(); i!=s.interface_blocks.end(); ++i)
 682                 if(i->second->instance_name.empty() && !used_interface_blocks.count(i->second))
 683                         unused_nodes.insert(i->second);
 684
 685         NodeRemover().apply(s, unused_nodes);
 686
 687         return !unused_nodes.empty();
 688 }
 689
 690 void UnusedVariableRemover::reference_used(Statement &declaration)
 691 {
 692         BlockVariableMap &block_vars = variables.back();
 693         /* Previous assignments of all subfields of this variable are used by
 694         this reference. */
 695         for(BlockVariableMap::iterator i=block_vars.lower_bound(&declaration); (i!=block_vars.end() && i->first.declaration==&declaration); ++i)
 696         {
 697                 clear_assignments(i->second, false);
 698                 i->second.referenced = true;
 699         }
 700
 701         // Always record a reference to the primary declaration, even if it didn't exist before
 702         block_vars[&declaration].referenced = true;
 703 }
 704
 705 void UnusedVariableRemover::visit(VariableReference &var)
 706 {
 707         if(var.declaration && !assignment_target)
 708                 reference_used(*var.declaration);
 709 }
 710
 711 void UnusedVariableRemover::visit(InterfaceBlockReference &iface)
 712 {
 713         if(iface.declaration && !assignment_target)
 714                 reference_used(*iface.declaration);
 715 }
 716
 717 void UnusedVariableRemover::visit(UnaryExpression &unary)
 718 {
 719         TraversingVisitor::visit(unary);
 720         if(unary.oper->token[1]=='+' || unary.oper->token[1]=='-')
 721                 r_side_effects = true;
 722 }
 723
 724 void UnusedVariableRemover::visit(BinaryExpression &binary)
 725 {
 726         if(binary.oper->token[0]=='[')
 727         {
 728                 binary.left->visit(*this);
 729                 SetFlag set(assignment_target, false);
 730                 binary.right->visit(*this);
 731         }
 732         else
 733                 TraversingVisitor::visit(binary);
 734 }
 735
 736 void UnusedVariableRemover::visit(Assignment &assign)
 737 {
 738         {
 739                 SetFlag set(assignment_target, !assign.self_referencing);
 740                 assign.left->visit(*this);
 741         }
 742         assign.right->visit(*this);
 743         r_assignment = &assign;
 744         r_side_effects = true;
 745 }
 746
 747 void UnusedVariableRemover::visit(FunctionCall &call)
 748 {
 749         TraversingVisitor::visit(call);
 750         /* Treat function calls as having side effects so expression statements
 751         consisting of nothing but a function call won't be optimized away. */
 752         r_side_effects = true;
 753 }
 754
 755 void UnusedVariableRemover::record_assignment(const Assignment::Target &target, Node &node, bool chained)
 756 {
 757         BlockVariableMap &block_vars = variables.back();
 758         for(BlockVariableMap::iterator i=block_vars.lower_bound(target); (i!=block_vars.end() && i->first.declaration==target.declaration); ++i)
 759         {
 760                 bool subfield = (i->first.chain_len>=target.chain_len);
 761                 for(unsigned j=0; (subfield && j<target.chain_len); ++j)
 762                         subfield = (i->first.chain[j]==target.chain[j]);
 763                 if(!subfield)
 764                         break;
 765
 766                 /* An assignment to the target causes any previous unreferenced
 767                 assignments to the same target or its subfields to be unused. */
 768                 if(!chained)
 769                         clear_assignments(i->second, true);
 770         }
 771
 772         VariableInfo &var_info = variables.back()[target];
 773         var_info.assignments.push_back(&node);
 774         var_info.conditionally_assigned = false;
 775 }
 776
 777 void UnusedVariableRemover::clear_assignments(VariableInfo &var_info, bool mark_unused)
 778 {
 779         if(mark_unused)
 780         {
 781                 for(vector<Node *>::iterator i=var_info.assignments.begin(); i!=var_info.assignments.end(); ++i)
 782                         unused_nodes.insert(*i);
 783         }
 784         var_info.assignments.clear();
 785 }
 786
 787 void UnusedVariableRemover::visit(ExpressionStatement &expr)
 788 {
 789         r_assignment = 0;
 790         r_side_effects = false;
 791         TraversingVisitor::visit(expr);
 792         if(r_assignment && r_assignment->target.declaration)
 793                 record_assignment(r_assignment->target, expr, r_assignment->self_referencing);
 794         if(!r_side_effects)
 795                 unused_nodes.insert(&expr);
 796 }
 797
 798 void UnusedVariableRemover::visit(VariableDeclaration &var)
 799 {
 800         VariableInfo &var_info = variables.back()[&var];
 801         var_info.local = true;
 802         var_info.interface_block = interface_block;
 803
 804         /* Mark variables as output if they're used by the next stage or the
 805         graphics API. */
 806         if(interface_block)
 807                 var_info.output = (interface_block->interface=="out" && (interface_block->linked_block || !interface_block->name.compare(0, 3, "gl_")));
 808         else
 809                 var_info.output = (var.interface=="out" && (stage->type==Stage::FRAGMENT || var.linked_declaration || !var.name.compare(0, 3, "gl_")));
 810
 811         if(var.init_expression)
 812                 record_assignment(&var, *var.init_expression, false);
 813         TraversingVisitor::visit(var);
 814 }
 815
 816 void UnusedVariableRemover::visit(InterfaceBlock &iface)
 817 {
 818         if(iface.instance_name.empty())
 819         {
 820                 SetForScope<InterfaceBlock *> set_block(interface_block, &iface);
 821                 iface.struct_declaration->members.visit(*this);
 822         }
 823         else
 824         {
 825                 VariableInfo &var_info = variables.back()[&iface];
 826                 var_info.local = true;
 827                 var_info.output = (iface.interface=="out" && (iface.linked_block || !iface.name.compare(0, 3, "gl_")));
 828         }
 829 }
 830
 831 void UnusedVariableRemover::visit(FunctionDeclaration &func)
 832 {
 833         variables.push_back(BlockVariableMap());
 834
 835         for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
 836                 (*i)->visit(*this);
 837         func.body.visit(*this);
 838
 839         BlockVariableMap &block_variables = variables.back();
 840
 841         /* Mark global variables as conditionally assigned so assignments in other
 842         functions won't be removed. */
 843         for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
 844                 if(!i->second.local)
 845                         i->second.conditionally_assigned = true;
 846
 847         /* Always treat function parameters as referenced.  Removing unused
 848         parameters is not currently supported. */
 849         for(NodeArray<VariableDeclaration>::iterator i=func.parameters.begin(); i!=func.parameters.end(); ++i)
 850                 block_variables[i->get()].referenced = true;
 851
 852         merge_down_variables();
 853 }
 854
 855 void UnusedVariableRemover::merge_down_variables()
 856 {
 857         BlockVariableMap &parent_variables = variables[variables.size()-2];
 858         BlockVariableMap &block_variables = variables.back();
 859         for(BlockVariableMap::iterator i=block_variables.begin(); i!=block_variables.end(); ++i)
 860         {
 861                 if(i->second.local)
 862                 {
 863                         if(!i->second.referenced && !i->first.chain_len)
 864                                 unused_nodes.insert(i->first.declaration);
 865                         /* Any unreferenced assignments when a variable runs out of scope
 866                         become unused. */
 867                         clear_assignments(i->second, true);
 868                         continue;
 869                 }
 870
 871                 BlockVariableMap::iterator j = parent_variables.find(i->first);
 872                 if(j==parent_variables.end())
 873                         parent_variables.insert(*i);
 874                 else
 875                 {
 876                         // Merge a non-local variable's state into the parent scope.
 877                         if(i->second.referenced || !i->second.conditionally_assigned)
 878                                 clear_assignments(j->second, !i->second.referenced);
 879                         j->second.conditionally_assigned = i->second.conditionally_assigned;
 880                         j->second.referenced |= i->second.referenced;
 881                         j->second.assignments.insert(j->second.assignments.end(), i->second.assignments.begin(), i->second.assignments.end());
 882                 }
 883         }
 884         variables.pop_back();
 885 }
 886
 887 void UnusedVariableRemover::visit(Conditional &cond)
 888 {
 889         cond.condition->visit(*this);
 890         variables.push_back(BlockVariableMap());
 891         cond.body.visit(*this);
 892
 893         BlockVariableMap if_variables;
 894         swap(variables.back(), if_variables);
 895         cond.else_body.visit(*this);
 896
 897         // Combine variables from both branches.
 898         BlockVariableMap &else_variables = variables.back();
 899         for(BlockVariableMap::iterator i=else_variables.begin(); i!=else_variables.end(); ++i)
 900         {
 901                 BlockVariableMap::iterator j = if_variables.find(i->first);
 902                 if(j!=if_variables.end())
 903                 {
 904                         // The variable was found in both branches.
 905                         i->second.assignments.insert(i->second.assignments.end(), j->second.assignments.begin(), j->second.assignments.end());
 906                         i->second.conditionally_assigned |= j->second.conditionally_assigned;
 907                         if_variables.erase(j);
 908                 }
 909                 else
 910                         // Mark variables found in only one branch as conditionally assigned.
 911                         i->second.conditionally_assigned = true;
 912         }
 913
 914         /* Move variables which were only used in the if block into the combined
 915         block. */
 916         for(BlockVariableMap::iterator i=if_variables.begin(); i!=if_variables.end(); ++i)
 917         {
 918                 i->second.conditionally_assigned = true;
 919                 else_variables.insert(*i);
 920         }
 921
 922         merge_down_variables();
 923 }
 924
 925 void UnusedVariableRemover::visit(Iteration &iter)
 926 {
 927         variables.push_back(BlockVariableMap());
 928         TraversingVisitor::visit(iter);
 929         merge_down_variables();
 930 }
 931
 932
 933 bool UnusedFunctionRemover::apply(Stage &stage)
 934 {
 935         stage.content.visit(*this);
 936         NodeRemover().apply(stage, unused_nodes);
 937         return !unused_nodes.empty();
 938 }
 939
 940 void UnusedFunctionRemover::visit(FunctionCall &call)
 941 {
 942         TraversingVisitor::visit(call);
 943
 944         unused_nodes.erase(call.declaration);
 945         if(call.declaration && call.declaration->definition!=call.declaration)
 946                 used_definitions.insert(call.declaration->definition);
 947 }
 948
 949 void UnusedFunctionRemover::visit(FunctionDeclaration &func)
 950 {
 951         TraversingVisitor::visit(func);
 952
 953         if((func.name!="main" || func.body.body.empty()) && !used_definitions.count(&func))
 954                 unused_nodes.insert(&func);
 955 }
 956
 957 } // namespace SL
 958 } // namespace GL
 959 } // namespace Msp