Private symbols as WeakMap sugar

Brendan Eich brendan at
Wed Jan 16 12:44:39 PST 2013

David Bruant wrote:
> Le 16/01/2013 21:19, Brendan Eich a écrit :
>> David Bruant wrote:
>>> Am I misunderstanding how JIT compilation using type information works? 
>> The problem is not just adding another deoptimization path. Not all 
>> JITs use only PICs. Lots of optimizations are possible. But adding a 
>> ?: to the *generic* (I meant what I wrote there) path is not going to 
>> fly, in my view.
> I still don't understand what you mean by "generic"? Does it mean 
> adding it to the spec algorithm?

No, it means any place where PIC overflows due to megamorphism and 
generic code must be used, or TI fails due to too many types or the 
"any" type.

> And I don't understand why it would be making a situation worse than 
> the binary + situation (PIC or not).

See above. Every generic []-operator usage is taxed.


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