Reland: [Parse] ParseInfo owns the parsing Zone.

src/parsing/parse-info.h

 // Copyright 2016 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.
 
 #ifndef V8_PARSING_PARSE_INFO_H_
 #define V8_PARSING_PARSE_INFO_H_
 
+#include <memory>
+
 #include "include/v8.h"
 #include "src/globals.h"
 #include "src/handles.h"
 #include "src/objects/scope-info.h"
 
 namespace v8 {
 
 class Extension;
 
 namespace internal {
 
+class AccountingAllocator;
 class AstRawString;
 class AstValueFactory;
 class DeclarationScope;
 class FunctionLiteral;
 class ScriptData;
 class SharedFunctionInfo;
 class UnicodeCache;
 class Utf16CharacterStream;
 class Zone;
 
 // A container for the inputs, configuration options, and outputs of parsing.
 class V8_EXPORT_PRIVATE ParseInfo {
  public:
-  explicit ParseInfo(Zone* zone);
-  ParseInfo(Zone* zone, Handle<Script> script);
-  ParseInfo(Zone* zone, Handle<SharedFunctionInfo> shared);
+  explicit ParseInfo(AccountingAllocator* zone_allocator);
+  ParseInfo(Handle<Script> script);
+  ParseInfo(Handle<SharedFunctionInfo> shared);
+
+  // TODO(rmcilroy): Remove once Hydrogen no longer needs this.
+  ParseInfo(Handle<SharedFunctionInfo> shared, std::shared_ptr<Zone> zone);
 
   ~ParseInfo();
 
-  Zone* zone() const { return zone_; }
+  Zone* zone() const { return zone_.get(); }

[marja, 2017/01/17 15:39:08]

Based on this CL, it's not possible to see whether the changes are correct or
not. I'd need to go and check every zone() caller to see whether any of them is
saving this pointer and using it after ParseInfo is gone. :/

[rmcilroy, 2017/01/19 12:48:29]

Given that the existing zone which was created always had the same lifetime as
the parseinfo I think this is fine, as you say all the uses of this are
temporary (and they should be since AFAIK the expectation in the style guide is
that you never stash away raw pointers you receive, only std::unique_ptr or
std::shared_ptr where you are explicilty transferring ownership).

+
+  std::shared_ptr<Zone> zone_shared() const { return zone_; }
 
 // Convenience accessor methods for flags.
 #define FLAG_ACCESSOR(flag, getter, setter)     \
   bool getter() const { return GetFlag(flag); } \
   void setter() { SetFlag(flag); }              \
   void setter(bool val) { SetFlag(flag, val); }
 
   FLAG_ACCESSOR(kToplevel, is_toplevel, set_toplevel)
   FLAG_ACCESSOR(kEval, is_eval, set_eval)
   FLAG_ACCESSOR(kStrictMode, is_strict_mode, set_strict_mode)
@@ skipping 168 matching lines @@
     kAllowLazyParsing = 1 << 7,
     kIsNamedExpression = 1 << 8,
     kCallsEval = 1 << 9,
     kDebug = 1 << 10,
     kSerializing = 1 << 11,
     // ---------- Output flags --------------------------
     kAstValueFactoryOwned = 1 << 12
   };
 
   //------------- Inputs to parsing and scope analysis -----------------------
-  Zone* zone_;
+  std::shared_ptr<Zone> zone_;
   unsigned flags_;
   ScriptCompiler::ExternalSourceStream* source_stream_;
   ScriptCompiler::StreamedSource::Encoding source_stream_encoding_;
   Utf16CharacterStream* character_stream_;
   v8::Extension* extension_;
   ScriptCompiler::CompileOptions compile_options_;
   DeclarationScope* script_scope_;
   DeclarationScope* asm_function_scope_;
   UnicodeCache* unicode_cache_;
   uintptr_t stack_limit_;
@@ skipping 20 matching lines @@
 
   void SetFlag(Flag f) { flags_ |= f; }
   void SetFlag(Flag f, bool v) { flags_ = v ? flags_ | f : flags_ & ~f; }
   bool GetFlag(Flag f) const { return (flags_ & f) != 0; }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSE_INFO_H_