Refactor Parser to make it usable on a background thread.

src/parser.cc

 // 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/api.h"
 #include "src/ast.h"
 #include "src/base/platform/platform.h"
 #include "src/bootstrapper.h"
@@ skipping 721 matching lines @@
     FunctionLiteral::FunctionType type,
     FunctionLiteral::ArityRestriction arity_restriction,
     bool* ok) {
   return parser_->ParseFunctionLiteral(name, function_name_location,
                                        name_is_strict_reserved, is_generator,
                                        function_token_position, type,
                                        arity_restriction, ok);
 }
 
 
-Parser::Parser(CompilationInfo* info)
-    : ParserBase<ParserTraits>(
-          &scanner_, info->isolate()->stack_guard()->real_climit(),
-          info->extension(), NULL, info->zone(), info->ast_node_id_gen(), this),
+Parser::Parser(CompilationInfo* info, uintptr_t stack_limit, uint32_t hash_seed,
+               UnicodeCache* unicode_cache)
+    : ParserBase<ParserTraits>(&scanner_, stack_limit, info->extension(), NULL,
+                               info->zone(), info->ast_node_id_gen(), this),
       isolate_(info->isolate()),
       script_(info->script()),
-      scanner_(isolate_->unicode_cache()),
+      scanner_(unicode_cache),
       reusable_preparser_(NULL),
       original_scope_(NULL),
       target_stack_(NULL),
       cached_parse_data_(NULL),
       ast_value_factory_(NULL),
       info_(info),
       has_pending_error_(false),
       pending_error_message_(NULL),
       pending_error_arg_(NULL),
-      pending_error_char_arg_(NULL) {
+      pending_error_char_arg_(NULL),
+      total_preparse_skipped_(0),
+      pre_parse_timer_(NULL),
+      hash_seed_(hash_seed) {
   DCHECK(!script_.is_null());
   set_allow_harmony_scoping(!info->is_native() && FLAG_harmony_scoping);
   set_allow_modules(!info->is_native() && FLAG_harmony_modules);
   set_allow_natives_syntax(FLAG_allow_natives_syntax || info->is_native());
   set_allow_lazy(false);  // Must be explicitly enabled.
   set_allow_generators(FLAG_harmony_generators);
   set_allow_arrow_functions(FLAG_harmony_arrow_functions);
   set_allow_harmony_numeric_literals(FLAG_harmony_numeric_literals);
   set_allow_classes(FLAG_harmony_classes);
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     use_counts_[feature] = 0;
   }
 }
 
 
 FunctionLiteral* Parser::ParseProgram() {
   // TODO(bmeurer): We temporarily need to pass allow_nesting = true here,
   // see comment for HistogramTimerScope class.
+
+  // It's OK to use the counters here, since this function is only called in
+  // the main thread.
   HistogramTimerScope timer_scope(isolate()->counters()->parse(), true);
   Handle<String> source(String::cast(script_->source()));
   isolate()->counters()->total_parse_size()->Increment(source->length());
   base::ElapsedTimer timer;
   if (FLAG_trace_parse) {
     timer.Start();
   }
   fni_ = new(zone()) FuncNameInferrer(ast_value_factory_, zone());
 
   // Initialize parser state.
@@ skipping 13 matching lines @@
     // identical calls.
     ExternalTwoByteStringUtf16CharacterStream stream(
         Handle<ExternalTwoByteString>::cast(source), 0, source->length());
     scanner_.Initialize(&stream);
     result = DoParseProgram(info(), source);
   } else {
     GenericStringUtf16CharacterStream stream(source, 0, source->length());
     scanner_.Initialize(&stream);
     result = DoParseProgram(info(), source);
   }
+  HandleSourceURLComments();
 
   if (FLAG_trace_parse && result != NULL) {
     double ms = timer.Elapsed().InMillisecondsF();
     if (info()->is_eval()) {
       PrintF("[parsing eval");
     } else if (info()->script()->name()->IsString()) {
       String* name = String::cast(info()->script()->name());
       SmartArrayPointer<char> name_chars = name->ToCString();
       PrintF("[parsing script: %s", name_chars.get());
     } else {
@@ skipping 48 matching lines @@
     // Enters 'scope'.
     FunctionState function_state(&function_state_, &scope_, scope, zone(),
                                  ast_value_factory_, info->ast_node_id_gen());
 
     scope_->SetStrictMode(info->strict_mode());
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16, zone());
     bool ok = true;
     int beg_pos = scanner()->location().beg_pos;
     ParseSourceElements(body, Token::EOS, info->is_eval(), true, &ok);
 
-    HandleSourceURLComments();
-
     if (ok && strict_mode() == STRICT) {
       CheckOctalLiteral(beg_pos, scanner()->location().end_pos, &ok);
     }
 
     if (ok && allow_harmony_scoping() && strict_mode() == STRICT) {
       CheckConflictingVarDeclarations(scope_, &ok);
     }
 
     if (ok && info->parse_restriction() == ONLY_SINGLE_FUNCTION_LITERAL) {
       if (body->length() != 1 ||
           !body->at(0)->IsExpressionStatement() ||
           !body->at(0)->AsExpressionStatement()->
               expression()->IsFunctionLiteral()) {
         ReportMessage("single_function_literal");
         ok = false;
       }
     }
 
-    ast_value_factory_->Internalize(isolate());
     if (ok) {
       result = factory()->NewFunctionLiteral(
           ast_value_factory_->empty_string(), ast_value_factory_, scope_, body,
           function_state.materialized_literal_count(),
           function_state.expected_property_count(),
           function_state.handler_count(), 0,
           FunctionLiteral::kNoDuplicateParameters,
           FunctionLiteral::ANONYMOUS_EXPRESSION, FunctionLiteral::kGlobalOrEval,
           FunctionLiteral::kNotParenthesized, FunctionLiteral::kNormalFunction,
           0);
       result->set_ast_properties(factory()->visitor()->ast_properties());
       result->set_dont_optimize_reason(
           factory()->visitor()->dont_optimize_reason());
-    } else if (stack_overflow()) {
-      isolate()->StackOverflow();
-    } else {
-      ThrowPendingError();
     }
   }
 
   // Make sure the target stack is empty.
   DCHECK(target_stack_ == NULL);
 
   return result;
 }
 
 
 FunctionLiteral* Parser::ParseLazy() {
+  // It's OK to use the counters here, since this function is only called in
+  // the main thread.
   HistogramTimerScope timer_scope(isolate()->counters()->parse_lazy());
   Handle<String> source(String::cast(script_->source()));
   isolate()->counters()->total_parse_size()->Increment(source->length());
   base::ElapsedTimer timer;
   if (FLAG_trace_parse) {
     timer.Start();
   }
   Handle<SharedFunctionInfo> shared_info = info()->shared_info();
 
   // Initialize parser state.
@@ skipping 72 matching lines @@
                                     function_type,
                                     FunctionLiteral::NORMAL_ARITY, &ok);
     }
     // Make sure the results agree.
     DCHECK(ok == (result != NULL));
   }
 
   // Make sure the target stack is empty.
   DCHECK(target_stack_ == NULL);
 
-  ast_value_factory_->Internalize(isolate());
-  if (result == NULL) {
-    if (stack_overflow()) {
-      isolate()->StackOverflow();
-    } else {
-      ThrowPendingError();
-    }
-  } else {
+  if (result != NULL) {
     Handle<String> inferred_name(shared_info->inferred_name());
     result->set_inferred_name(inferred_name);
   }
   return result;
 }
 
 
 void* Parser::ParseSourceElements(ZoneList<Statement*>* processor,
                                   int end_token,
                                   bool is_eval,
@@ skipping 2609 matching lines @@
     CHECK(entry.is_valid());
     // End position greater than end of stream is safe, and hard to check.
     CHECK(entry.end_pos() > function_block_pos);
     scanner()->SeekForward(entry.end_pos() - 1);
 
     scope_->set_end_position(entry.end_pos());
     Expect(Token::RBRACE, ok);
     if (!*ok) {
       return;
     }
-    isolate()->counters()->total_preparse_skipped()->Increment(
-        scope_->end_position() - function_block_pos);
+    total_preparse_skipped_ += scope_->end_position() - function_block_pos;
     *materialized_literal_count = entry.literal_count();
     *expected_property_count = entry.property_count();
     scope_->SetStrictMode(entry.strict_mode());
   } else {
     // With no cached data, we partially parse the function, without building an
     // AST. This gathers the data needed to build a lazy function.
     SingletonLogger logger;
     PreParser::PreParseResult result =
         ParseLazyFunctionBodyWithPreParser(&logger);
     if (result == PreParser::kPreParseStackOverflow) {
       // Propagate stack overflow.
       set_stack_overflow();
       *ok = false;
       return;
     }
     if (logger.has_error()) {
       ParserTraits::ReportMessageAt(
           Scanner::Location(logger.start(), logger.end()),
           logger.message(), logger.argument_opt(), logger.is_reference_error());
       *ok = false;
       return;
     }
     scope_->set_end_position(logger.end());
     Expect(Token::RBRACE, ok);
     if (!*ok) {
       return;
     }
-    isolate()->counters()->total_preparse_skipped()->Increment(
-        scope_->end_position() - function_block_pos);
+    total_preparse_skipped_ += scope_->end_position() - function_block_pos;
     *materialized_literal_count = logger.literals();
     *expected_property_count = logger.properties();
     scope_->SetStrictMode(logger.strict_mode());
     if (compile_options() == ScriptCompiler::kProduceParserCache) {
       DCHECK(log_);
       // Position right after terminal '}'.
       int body_end = scanner()->location().end_pos;
       log_->LogFunction(function_block_pos, body_end,
                         *materialized_literal_count,
                         *expected_property_count,
@@ skipping 57 matching lines @@
 
   Expect(Token::RBRACE, CHECK_OK);
   scope_->set_end_position(scanner()->location().end_pos);
 
   return body;
 }
 
 
 PreParser::PreParseResult Parser::ParseLazyFunctionBodyWithPreParser(
     SingletonLogger* logger) {
-  HistogramTimerScope preparse_scope(isolate()->counters()->pre_parse());
+  // This function may be called on a background thread too; record only the
+  // main thread preparse times.
+  if (pre_parse_timer_ != NULL) {
+    pre_parse_timer_->Start();
+  }
   DCHECK_EQ(Token::LBRACE, scanner()->current_token());
 
   if (reusable_preparser_ == NULL) {
-    intptr_t stack_limit = isolate()->stack_guard()->real_climit();
-    reusable_preparser_ = new PreParser(&scanner_, NULL, stack_limit);
+    reusable_preparser_ = new PreParser(&scanner_, NULL, stack_limit_);
     reusable_preparser_->set_allow_harmony_scoping(allow_harmony_scoping());
     reusable_preparser_->set_allow_modules(allow_modules());
     reusable_preparser_->set_allow_natives_syntax(allow_natives_syntax());
     reusable_preparser_->set_allow_lazy(true);
     reusable_preparser_->set_allow_generators(allow_generators());
     reusable_preparser_->set_allow_arrow_functions(allow_arrow_functions());
     reusable_preparser_->set_allow_harmony_numeric_literals(
         allow_harmony_numeric_literals());
     reusable_preparser_->set_allow_classes(allow_classes());
   }
   PreParser::PreParseResult result =
       reusable_preparser_->PreParseLazyFunction(strict_mode(),
                                                 is_generator(),
                                                 logger);
+  if (pre_parse_timer_ != NULL) {
+    pre_parse_timer_->Stop();
+  }
   return result;
 }
 
 
 Expression* Parser::ParseV8Intrinsic(bool* ok) {
   // CallRuntime ::
   //   '%' Identifier Arguments
 
   int pos = peek_position();
   Expect(Token::MOD, CHECK_OK);
@@ skipping 163 matching lines @@
     Handle<Object> error;
     MaybeHandle<Object> maybe_error =
         pending_error_is_reference_error_
             ? factory->NewReferenceError(pending_error_message_, array)
             : factory->NewSyntaxError(pending_error_message_, array);
     if (maybe_error.ToHandle(&error)) isolate()->Throw(*error, &location);
   }
 }
 
 
-void Parser::InternalizeUseCounts() {
+void Parser::Internalize() {
+  // Internalize strings.
+  ast_value_factory_->Internalize(isolate());
+
+  // Error processing.
+  if (info()->function() == NULL) {
+    if (stack_overflow()) {
+      isolate()->StackOverflow();
+    } else {
+      ThrowPendingError();
+    }
+  }
+
+  // Move statistics to Isolate.
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     for (int i = 0; i < use_counts_[feature]; ++i) {
       isolate()->CountUsage(v8::Isolate::UseCounterFeature(feature));
     }
   }
+  isolate()->counters()->total_preparse_skipped()->Increment(
+      total_preparse_skipped_);
 }
 
 
 // ----------------------------------------------------------------------------
 // Regular expressions
 
 
 RegExpParser::RegExpParser(FlatStringReader* in,
                            Handle<String>* error,
                            bool multiline,
@@ skipping 819 matching lines @@
   }
   return !parser.failed();
 }
 
 
 bool Parser::Parse() {
   DCHECK(info()->function() == NULL);
   FunctionLiteral* result = NULL;
   ast_value_factory_ = info()->ast_value_factory();
   if (ast_value_factory_ == NULL) {
-    ast_value_factory_ =
-        new AstValueFactory(zone(), isolate()->heap()->HashSeed());
+    ast_value_factory_ = new AstValueFactory(zone(), hash_seed_);
   }
   if (allow_natives_syntax() || extension_ != NULL) {
     // If intrinsics are allowed, the Parser cannot operate independent of the
     // V8 heap because of Rumtime. Tell the string table to internalize strings
     // and values right after they're created.
     ast_value_factory_->Internalize(isolate());
   }
-
+  pre_parse_timer_ = isolate()->counters()->pre_parse();
   if (info()->is_lazy()) {
     DCHECK(!info()->is_eval());
     if (info()->shared_info()->is_function()) {
       result = ParseLazy();
     } else {
       result = ParseProgram();
     }
   } else {
     SetCachedData();
     result = ParseProgram();
   }
   info()->SetFunction(result);
+
+  Internalize();
   DCHECK(ast_value_factory_->IsInternalized());
   // info takes ownership of ast_value_factory_.
   if (info()->ast_value_factory() == NULL) {
     info()->SetAstValueFactory(ast_value_factory_);
   }
   ast_value_factory_ = NULL;
-
-  InternalizeUseCounts();
-
   return (result != NULL);
 }
 
 } }  // namespace v8::internal