On Tue, Feb 10, 2015 at 6:46 PM, <obaste...@gmail.com> wrote:
> Is there any reason why ION marks the below first function to not_compile,
> while it's not a problem for the second ?
>
> 1 - function x() { var arr = []; arr[0] = 1; ...some_other_things... }
>
> 2 - function x() { var arr = new Array(); arr[0] = 1; .......... }
>
>
> 'array(opcode 190) is not typed?'
>
Can you be more specific? Which Firefox/SM version did you use? Where did
you see the "is not typed" message? What do you mean by "not_compile"? Ion
should handle those two functions without any problems, as far as I know.
> The current 'op-code' interpreter implementation is 'switch-case'. Most
> compilers will be converting that into a binary tree (which is fast enough,
> but the worst case is ~8 (~300 op codes)).
>
> Although it's a big change, is there any plan for updating that part to a
> jump table ? I didn't track yet but would you expect a significant
> performance gain from there.
>
C++ compilers are smart enough to emit a jump table for switch statements
like this one. On some platforms we do something even better (indirect
goto), see bug 910782 [0] and the comment at the start of Interpret in
js/src/vm/Interpreter.cpp.
Jan
[0] https://bugzilla.mozilla.org/show_bug.cgi?id=910782
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