[Compiler] Use shared_ptr for ast_value_factory in ParseInfo.

Rather than using an ad-hock ownership model for ast_value_factory, use a
shared_ptr.

BUG=v8:5203

Change-Id: I5f2a573c8b175a3138ad8b01aa78bddadd16e6d3
Reviewed-on: https://chromium-review.googlesource.com/582628
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46874}

src/ast/ast.h

@@ -3058,9 +3058,6 @@ class AstNodeFactory final BASE_EMBEDDED {
       : zone_(zone), ast_value_factory_(ast_value_factory) {}
 
   AstValueFactory* ast_value_factory() const { return ast_value_factory_; }
-  void set_ast_value_factory(AstValueFactory* ast_value_factory) {
-    ast_value_factory_ = ast_value_factory;
-  }
 
   VariableDeclaration* NewVariableDeclaration(VariableProxy* proxy,
                                               Scope* scope, int pos) {

src/compiler.cc

@@ -501,11 +501,9 @@ bool CompileUnoptimizedInnerFunctions(
       parse_info.set_literal(literal);
       parse_info.set_function_literal_id(shared->function_literal_id());
       parse_info.set_language_mode(literal->scope()->language_mode());
-      parse_info.set_ast_value_factory(
-          outer_info->parse_info()->ast_value_factory());
-      parse_info.set_ast_value_factory_owned(false);
       parse_info.set_source_range_map(
           outer_info->parse_info()->source_range_map());
+      parse_info.ShareAstValueFactory(outer_info->parse_info());
 
       if (will_serialize) info.PrepareForSerializing();
       if (is_debug) info.MarkAsDebug();

src/parsing/parse-info.cc

@@ -93,14 +93,6 @@ ParseInfo::ParseInfo(Handle<Script> script)
   set_collect_type_profile(FLAG_type_profile && script->IsUserJavaScript());
 }
 
-ParseInfo::~ParseInfo() {
-  if (ast_value_factory_owned()) {
-    delete ast_value_factory_;
-    set_ast_value_factory_owned(false);
-  }
-  ast_value_factory_ = nullptr;
-}
-
 // static
 ParseInfo* ParseInfo::AllocateWithoutScript(Handle<SharedFunctionInfo> shared) {
   Isolate* isolate = shared->GetIsolate();
@@ -201,6 +193,19 @@ std::map<int, ParseInfo*> ParseInfo::child_infos() const {
   return rv;
 }
 
+AstValueFactory* ParseInfo::GetOrCreateAstValueFactory() {
+  if (!ast_value_factory_.get()) {
+    ast_value_factory_.reset(
+        new AstValueFactory(zone(), ast_string_constants(), hash_seed()));
+  }
+  return ast_value_factory();
+}
+
+void ParseInfo::ShareAstValueFactory(ParseInfo* other) {
+  DCHECK(!ast_value_factory_.get());
+  ast_value_factory_ = other->ast_value_factory_;
+}
+
 #ifdef DEBUG
 bool ParseInfo::script_is_native() const {
   return script_->type() == Script::TYPE_NATIVE;

src/parsing/parse-info.h

@@ -42,12 +42,19 @@ class V8_EXPORT_PRIVATE ParseInfo : public CompileJobFinishCallback {
   ParseInfo(Handle<Script> script);
   ParseInfo(Handle<SharedFunctionInfo> shared);
 
-  ~ParseInfo();
+  ~ParseInfo() {}
 
   void InitFromIsolate(Isolate* isolate);
 
   static ParseInfo* AllocateWithoutScript(Handle<SharedFunctionInfo> shared);
 
+  // Either returns the ast-value-factory associcated with this ParseInfo, or
+  // creates and returns a new factory if none exists.
+  AstValueFactory* GetOrCreateAstValueFactory();
+
+  // Sets this parse info to share the same ast value factory as |other|.
+  void ShareAstValueFactory(ParseInfo* other);
+
   Zone* zone() const { return zone_.get(); }
 
   std::shared_ptr<Zone> zone_shared() const { return zone_; }
@@ -70,8 +77,6 @@ class V8_EXPORT_PRIVATE ParseInfo : public CompileJobFinishCallback {
   FLAG_ACCESSOR(kNative, is_native, set_native)
   FLAG_ACCESSOR(kModule, is_module, set_module)
   FLAG_ACCESSOR(kAllowLazyParsing, allow_lazy_parsing, set_allow_lazy_parsing)
-  FLAG_ACCESSOR(kAstValueFactoryOwned, ast_value_factory_owned,
-                set_ast_value_factory_owned)
   FLAG_ACCESSOR(kIsNamedExpression, is_named_expression,
                 set_is_named_expression)
   FLAG_ACCESSOR(kDebug, is_debug, set_is_debug)
@@ -136,9 +141,9 @@ class V8_EXPORT_PRIVATE ParseInfo : public CompileJobFinishCallback {
     asm_function_scope_ = scope;
   }
 
-  AstValueFactory* ast_value_factory() const { return ast_value_factory_; }
-  void set_ast_value_factory(AstValueFactory* ast_value_factory) {
-    ast_value_factory_ = ast_value_factory;
+  AstValueFactory* ast_value_factory() const {
+    DCHECK(ast_value_factory_.get());
+    return ast_value_factory_.get();
   }
 
   const AstRawString* function_name() const { return function_name_; }
@@ -270,7 +275,6 @@ class V8_EXPORT_PRIVATE ParseInfo : public CompileJobFinishCallback {
     kIsNamedExpression = 1 << 8,
     kDebug = 1 << 9,
     kSerializing = 1 << 10,
-    kAstValueFactoryOwned = 1 << 11,
     kCollectTypeProfile = 1 << 12,
   };
 
@@ -301,7 +305,7 @@ class V8_EXPORT_PRIVATE ParseInfo : public CompileJobFinishCallback {
   //----------- Inputs+Outputs of parsing and scope analysis -----------------
   ScriptData** cached_data_;  // used if available, populated if requested.
   ConsumedPreParsedScopeData consumed_preparsed_scope_data_;
-  AstValueFactory* ast_value_factory_;  // used if available, otherwise new.
+  std::shared_ptr<AstValueFactory> ast_value_factory_;
   const class AstStringConstants* ast_string_constants_;
   const AstRawString* function_name_;
   RuntimeCallStats* runtime_call_stats_;

src/parsing/parser.cc

@@ -478,7 +478,7 @@ Expression* Parser::NewV8Intrinsic(const AstRawString* name,
 
 Parser::Parser(ParseInfo* info)
     : ParserBase<Parser>(info->zone(), &scanner_, info->stack_limit(),
-                         info->extension(), info->ast_value_factory(),
+                         info->extension(), info->GetOrCreateAstValueFactory(),
                          info->runtime_call_stats(), true),
       scanner_(info->unicode_cache()),
       reusable_preparser_(nullptr),
@@ -529,14 +529,6 @@ Parser::Parser(ParseInfo* info)
        ++feature) {
     use_counts_[feature] = 0;
   }
-  if (info->ast_value_factory() == NULL) {
-    // info takes ownership of AstValueFactory.
-    info->set_ast_value_factory(new AstValueFactory(
-        zone(), info->ast_string_constants(), info->hash_seed()));
-    info->set_ast_value_factory_owned();
-    ast_value_factory_ = info->ast_value_factory();
-    ast_node_factory_.set_ast_value_factory(ast_value_factory_);
-  }
 }
 
 void Parser::DeserializeScopeChain(