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