1605101 - [meta] js::Stencil data structures

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P3)

Description

[Ted Campbell [:tcampbell]]

This is a meta-bug for the design of data structures for Bug 1601332. Also includes cleanup work on types shared with runtime (such as definition of flags).

Current Objectives (subject to change):

• No GC pointers
• Defined in Rust with C++ bindings
• Simplified model vs the final runtime script model
• Avoid cyclic references
• Straightforward serialization to disk
• Use formats like js::ImmutableScriptData directly

The current C++ frontend and the new frontend should be migrated to targeting this format.

Comment 1

[Ted Campbell [:tcampbell]]

The rough set of types I think we want are:

• Stencil (top-level)
  • parse-flags
  • BaseScript::ImmutableFlags
  • js::ImmutableScriptData
  • Maybe<exports>
  • Maybe<imports>
• Function
  • AllocKind/group-hint flags
  • FunctionFlags
  • BaseScript::ImmutableFlags
  • Maybe<js::ImmutableScriptData>
• Scope
  • scope-kind
  • ScopeData
  • enclosing scope reference
• ObjectLiteral
• BigIntLiteral

Things such as shapes and environments are hopefully implied easily by the rest of the data. A lazy function should just be a function without ImmutableScriptData. I've glossed over how JSAtom* will be handled.

Comment 3

[Ted Campbell [:tcampbell]]

The data structures are now workable so I'll close this bug.