Optimized Functions Plans

[cblappert]

Planning for optimized functions (original issue #799) mostly for H2 2018, but some stuff for past then. Under each category, the items are in rough order of priority

Anything italicized is wishlist and is not currently a priority.

Anything with a :small_orange_diamond: in front is 2nd priority once all unmarked items are completed.

• Correctness
  • Nested Optimized Functions
    • [ ] Become confident in correctness of output
      • possibly look into extending @calebmer's fuzzer
    • [x] Nested __optimize calls #1398
  • Bindings
    • [ ] Havoc Bugs
      • [x] Fix initialization of bindings used by havoc #2335
      • [ ] Fix havocing of templates within optimized functions #2217
    • [ ] Optimized functions capturing bindings of residual functions
    • [ ] Captured bindings for nested optimized functions #1615
  • General Bugfixes
    • [ ] Make sure all outstanding invariant failures on React Fusion are gone
      • [x] #2252
      • [x] #2392
      • [x] #2383
      • [x] React Compiler Optimized Function Bugs
      • [ ] All Optimized Function Bugs
    • [x] :small_orange_diamond: Proper support for possible exceptions (with @hermanventer)
• Enhancements
  • [ ] Add option to optimize functions at the site of the __optimize call #2336
    • for supporting calls inside of map and filter
  • [x] Investigation: Talk to @NTillman to understand asks for Instant Render
  • :small_orange_diamond: Code Bloat
    • [ ] eliminate redundant unobservable intermediate states of properties/bindings
    • [x] #2276 correct precise capture of bindings
  • [x] :small_orange_diamond: Add support for usage of this in optimized functions #1640
  • [ ] add compatibility for lazy initialization
  • [ ] add support for bound functions #2213
  • [ ] widen when optimized functions have side-effects #1750
• Better Engineering
  • [x] Stop applying/reverting effects in serializer multiple times per optimize function
    • Probably will be done as a part of @hermanventer's refactor
  • [ ] Add documentation/examples for optimized functions in the wiki page
    • Ensure there are examples for all of the limitations/assumptions/optimizations
  • [ ] Enhance serializer tests using automated heap traversal #1852