s/%HasElement(i, array)/%HasElement(array, i)/ Vyacheslav Egorov
On Tue, Aug 13, 2013 at 6:04 PM, Vyacheslav Egorov <[email protected]>wrote: > DBC: > > Can't we just manually inline 'in' here? > > if I am not mistaken x in y essentially just calls IN function from > runtime.js > > In this particular case you should be able just to replace i in array > with %HasElement(i, array) and hopefully fast path in the %HasElement would > take care of the rest. > > Ideally Crankshaft should take care of this but well... One can dream :-) > > Vyacheslav Egorov > > > On Tue, Aug 13, 2013 at 5:47 PM, <[email protected]> wrote: > >> >> https://codereview.chromium.**org/22545007/diff/20001/src/**array.js<https://codereview.chromium.org/22545007/diff/20001/src/array.js> >> File src/array.js (right): >> >> https://codereview.chromium.**org/22545007/diff/20001/src/** >> array.js#newcode1263<https://codereview.chromium.org/22545007/diff/20001/src/array.js#newcode1263> >> src/array.js:1263: if (!isProxy && %HasFastPackedElements(array) || i in >> array) { >> On 2013/08/13 14:10:22, Michael Starzinger wrote: >> >>> It is _really_ surprising that the runtime call into >>> Runtime_HasFastPackedElements is cheaper than the "in" keyword. This >>> >> suggests >> >>> that there is a lot of potential in actually improving "in" in >>> >> general. This >> >>> needs investigation of the generated code! >>> >> >> Now that I think about it, I don't actually think that this is a valid >> optimization either. What happens if the callback actually changes the >> array in a way so that it remains in fast-packed mode, but "i" still >> runs out of bounds. Imagine the following callback. >> >> var array = [1,2,3,4,5,6]; >> Object.defineProperty(array, '1', { >> get: function () { array.length = 3; }, >> configurable: true >> }); >> array.forEach(f); >> >> >> https://codereview.chromium.**org/22545007/<https://codereview.chromium.org/22545007/> >> >> -- >> -- >> v8-dev mailing list >> [email protected] >> http://groups.google.com/**group/v8-dev<http://groups.google.com/group/v8-dev> >> ---You received this message because you are subscribed to the Google >> Groups "v8-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to >> v8-dev+unsubscribe@**googlegroups.com<v8-dev%[email protected]> >> . >> For more options, visit >> https://groups.google.com/**groups/opt_out<https://groups.google.com/groups/opt_out> >> . >> > > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
