Closed Bug 750279 (UntangleFrontEnd) Opened 8 years ago Closed 8 years ago

[meta] Untangle front-end state


(Core :: JavaScript Engine, defect)

Not set





(Reporter: njn, Assigned: njn)



(Keywords: meta)

The front-end is a big ball of mud.  In particular, the state is very intertwined.  Examples:

- Parser has a pointer to TreeContext, and TreeContext has a pointer to Parser.  

- Parser.cpp includes BytecodeEmitter.h;  BytecodeEmitter.cpp includes Parser.h.

- BytecodeEmitter is a sub-class of TreeContext, but sometimes we down-cast TreeContext to BytecodeEmitter.

- The tcflags are a mish-mash of values with a range of lifetimes and mutability.  Some are set up-front and not changed;  some are set and cleared multiple times.  Some are relevant only in the parser; some are relevant in the parser and bytecode emitter.

As a result, any function that has access to any of the major pieces of front-end state -- Parser, TreeContext, BytecodeEmitter -- has access to pretty much all of it.  Speaking as someone who's only just started looking closely at the front-end, this makes things really hard to understand.

This is a tracking bug for cleaning this up.
Alias: UntangleFrontEnd
Depends on: 750282
Depends on: 750580
Depends on: 750606
Depends on: 751818
Depends on: 752758
Depends on: 752793
Depends on: 752816
Depends on: 753249
Depends on: 753657
Depends on: 754179
Depends on: 754180
Depends on: 754181
Depends on: 754739
Depends on: 757336
Depends on: 757690
Depends on: 759246
Depends on: 761914
Depends on: 764714
Depends on: 767202
Depends on: 770067
I think I'm done with this.
Closed: 8 years ago
Resolution: --- → FIXED
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