| // Copyright 2012 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/v8.h" |
| |
| #include "src/rewriter.h" |
| |
| #include "src/ast.h" |
| #include "src/compiler.h" |
| #include "src/scopes.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| class Processor: public AstVisitor { |
| public: |
| Processor(Variable* result, Zone* zone, AstNode::IdGen* ast_node_id_gen) |
| : result_(result), |
| result_assigned_(false), |
| is_set_(false), |
| in_try_(false), |
| // Passing a null AstValueFactory is fine, because Processor doesn't |
| // need to create strings or literals. |
| factory_(zone, NULL, ast_node_id_gen) { |
| InitializeAstVisitor(zone); |
| } |
| |
| virtual ~Processor() { } |
| |
| void Process(ZoneList<Statement*>* statements); |
| bool result_assigned() const { return result_assigned_; } |
| |
| AstNodeFactory<AstNullVisitor>* factory() { |
| return &factory_; |
| } |
| |
| private: |
| Variable* result_; |
| |
| // We are not tracking result usage via the result_'s use |
| // counts (we leave the accurate computation to the |
| // usage analyzer). Instead we simple remember if |
| // there was ever an assignment to result_. |
| bool result_assigned_; |
| |
| // To avoid storing to .result all the time, we eliminate some of |
| // the stores by keeping track of whether or not we're sure .result |
| // will be overwritten anyway. This is a bit more tricky than what I |
| // was hoping for |
| bool is_set_; |
| bool in_try_; |
| |
| AstNodeFactory<AstNullVisitor> factory_; |
| |
| Expression* SetResult(Expression* value) { |
| result_assigned_ = true; |
| VariableProxy* result_proxy = factory()->NewVariableProxy(result_); |
| return factory()->NewAssignment( |
| Token::ASSIGN, result_proxy, value, RelocInfo::kNoPosition); |
| } |
| |
| // Node visitors. |
| #define DEF_VISIT(type) \ |
| virtual void Visit##type(type* node); |
| AST_NODE_LIST(DEF_VISIT) |
| #undef DEF_VISIT |
| |
| void VisitIterationStatement(IterationStatement* stmt); |
| |
| DEFINE_AST_VISITOR_SUBCLASS_MEMBERS(); |
| }; |
| |
| |
| void Processor::Process(ZoneList<Statement*>* statements) { |
| for (int i = statements->length() - 1; i >= 0; --i) { |
| Visit(statements->at(i)); |
| } |
| } |
| |
| |
| void Processor::VisitBlock(Block* node) { |
| // An initializer block is the rewritten form of a variable declaration |
| // with initialization expressions. The initializer block contains the |
| // list of assignments corresponding to the initialization expressions. |
| // While unclear from the spec (ECMA-262, 3rd., 12.2), the value of |
| // a variable declaration with initialization expression is 'undefined' |
| // with some JS VMs: For instance, using smjs, print(eval('var x = 7')) |
| // returns 'undefined'. To obtain the same behavior with v8, we need |
| // to prevent rewriting in that case. |
| if (!node->is_initializer_block()) Process(node->statements()); |
| } |
| |
| |
| void Processor::VisitModuleStatement(ModuleStatement* node) { |
| bool set_after_body = is_set_; |
| Visit(node->body()); |
| is_set_ = is_set_ && set_after_body; |
| } |
| |
| |
| void Processor::VisitExpressionStatement(ExpressionStatement* node) { |
| // Rewrite : <x>; -> .result = <x>; |
| if (!is_set_ && !node->expression()->IsThrow()) { |
| node->set_expression(SetResult(node->expression())); |
| if (!in_try_) is_set_ = true; |
| } |
| } |
| |
| |
| void Processor::VisitIfStatement(IfStatement* node) { |
| // Rewrite both then and else parts (reversed). |
| bool save = is_set_; |
| Visit(node->else_statement()); |
| bool set_after_then = is_set_; |
| is_set_ = save; |
| Visit(node->then_statement()); |
| is_set_ = is_set_ && set_after_then; |
| } |
| |
| |
| void Processor::VisitIterationStatement(IterationStatement* node) { |
| // Rewrite the body. |
| bool set_after_loop = is_set_; |
| Visit(node->body()); |
| is_set_ = is_set_ && set_after_loop; |
| } |
| |
| |
| void Processor::VisitDoWhileStatement(DoWhileStatement* node) { |
| VisitIterationStatement(node); |
| } |
| |
| |
| void Processor::VisitWhileStatement(WhileStatement* node) { |
| VisitIterationStatement(node); |
| } |
| |
| |
| void Processor::VisitForStatement(ForStatement* node) { |
| VisitIterationStatement(node); |
| } |
| |
| |
| void Processor::VisitForInStatement(ForInStatement* node) { |
| VisitIterationStatement(node); |
| } |
| |
| |
| void Processor::VisitForOfStatement(ForOfStatement* node) { |
| VisitIterationStatement(node); |
| } |
| |
| |
| void Processor::VisitTryCatchStatement(TryCatchStatement* node) { |
| // Rewrite both try and catch blocks (reversed order). |
| bool set_after_catch = is_set_; |
| Visit(node->catch_block()); |
| is_set_ = is_set_ && set_after_catch; |
| bool save = in_try_; |
| in_try_ = true; |
| Visit(node->try_block()); |
| in_try_ = save; |
| } |
| |
| |
| void Processor::VisitTryFinallyStatement(TryFinallyStatement* node) { |
| // Rewrite both try and finally block (reversed order). |
| Visit(node->finally_block()); |
| bool save = in_try_; |
| in_try_ = true; |
| Visit(node->try_block()); |
| in_try_ = save; |
| } |
| |
| |
| void Processor::VisitSwitchStatement(SwitchStatement* node) { |
| // Rewrite statements in all case clauses in reversed order. |
| ZoneList<CaseClause*>* clauses = node->cases(); |
| bool set_after_switch = is_set_; |
| for (int i = clauses->length() - 1; i >= 0; --i) { |
| CaseClause* clause = clauses->at(i); |
| Process(clause->statements()); |
| } |
| is_set_ = is_set_ && set_after_switch; |
| } |
| |
| |
| void Processor::VisitContinueStatement(ContinueStatement* node) { |
| is_set_ = false; |
| } |
| |
| |
| void Processor::VisitBreakStatement(BreakStatement* node) { |
| is_set_ = false; |
| } |
| |
| |
| void Processor::VisitWithStatement(WithStatement* node) { |
| bool set_after_body = is_set_; |
| Visit(node->statement()); |
| is_set_ = is_set_ && set_after_body; |
| } |
| |
| |
| // Do nothing: |
| void Processor::VisitVariableDeclaration(VariableDeclaration* node) {} |
| void Processor::VisitFunctionDeclaration(FunctionDeclaration* node) {} |
| void Processor::VisitModuleDeclaration(ModuleDeclaration* node) {} |
| void Processor::VisitImportDeclaration(ImportDeclaration* node) {} |
| void Processor::VisitExportDeclaration(ExportDeclaration* node) {} |
| void Processor::VisitModuleLiteral(ModuleLiteral* node) {} |
| void Processor::VisitModuleVariable(ModuleVariable* node) {} |
| void Processor::VisitModulePath(ModulePath* node) {} |
| void Processor::VisitModuleUrl(ModuleUrl* node) {} |
| void Processor::VisitEmptyStatement(EmptyStatement* node) {} |
| void Processor::VisitReturnStatement(ReturnStatement* node) {} |
| void Processor::VisitDebuggerStatement(DebuggerStatement* node) {} |
| |
| |
| // Expressions are never visited yet. |
| #define DEF_VISIT(type) \ |
| void Processor::Visit##type(type* expr) { UNREACHABLE(); } |
| EXPRESSION_NODE_LIST(DEF_VISIT) |
| #undef DEF_VISIT |
| |
| |
| // Assumes code has been parsed. Mutates the AST, so the AST should not |
| // continue to be used in the case of failure. |
| bool Rewriter::Rewrite(CompilationInfo* info) { |
| FunctionLiteral* function = info->function(); |
| DCHECK(function != NULL); |
| Scope* scope = function->scope(); |
| DCHECK(scope != NULL); |
| if (!scope->is_global_scope() && !scope->is_eval_scope()) return true; |
| |
| ZoneList<Statement*>* body = function->body(); |
| if (!body->is_empty()) { |
| Variable* result = |
| scope->NewTemporary(info->ast_value_factory()->dot_result_string()); |
| // The name string must be internalized at this point. |
| DCHECK(!result->name().is_null()); |
| Processor processor(result, info->zone(), info->ast_node_id_gen()); |
| processor.Process(body); |
| if (processor.HasStackOverflow()) return false; |
| |
| if (processor.result_assigned()) { |
| DCHECK(function->end_position() != RelocInfo::kNoPosition); |
| // Set the position of the assignment statement one character past the |
| // source code, such that it definitely is not in the source code range |
| // of an immediate inner scope. For example in |
| // eval('with ({x:1}) x = 1'); |
| // the end position of the function generated for executing the eval code |
| // coincides with the end of the with scope which is the position of '1'. |
| int pos = function->end_position(); |
| VariableProxy* result_proxy = processor.factory()->NewVariableProxy( |
| result->raw_name(), false, result->interface(), pos); |
| result_proxy->BindTo(result); |
| Statement* result_statement = |
| processor.factory()->NewReturnStatement(result_proxy, pos); |
| body->Add(result_statement, info->zone()); |
| } |
| } |
| |
| return true; |
| } |
| |
| |
| } } // namespace v8::internal |