Cool, glad this has worked out.
I decided to play around a bit more and figured out a faster implementation
of TypedArray.prototype.fill() for arbitrary values BTW (3x improvement for
me):
```
function fill(arr, value) {
arr[0] = value
for (let i = 1; i < arr.length; i *= 2) {
arr.copyWithin(i, 0, i)
}
return arr
}
```
This works out because `TypedArray.prototype.copyWithin()` uses memmove.
Maybe worth doing for 16/32/64-bit typed arrays, perhaps even for plain old
javascript arrays?
Updated benchmark: https://jsbench.me/1zl3y8q6q7/2
On Friday, June 3, 2022 at 12:33:14 PM UTC+1 Jakob Kummerow wrote:
> I guess 0 is by far the most common case.
>
> A patch is easy enough:
> https://chromium-review.googlesource.com/c/v8/v8/+/3687700
>
> Locally, I'm seeing 1.5x - 2x improvement, far from 10x but clearly
> measurable for large arrays.
>
>
> On Fri, Jun 3, 2022 at 1:10 PM Leszek Swirski <[email protected]> wrote:
>
>> I guess we could do it for anything where all two/four bytes of the fill
>> value are identical? Probably (aside from 0) an unusual case like you say,
>> but the complexity of checking it should be low enough.
>>
>> On Fri, Jun 3, 2022 at 11:56 AM Marja Hölttä <[email protected]> wrote:
>>
>>> Interesting, thanks for making us / me aware of this.
>>>
>>> It sounds like a generally reasonable optimization; at least in the
>>> fill(0) case. Not sure how common fill(-1) is but if it doesn't increase
>>> the code complexity too much, why not.
>>>
>>>
>>> On Fri, Jun 3, 2022 at 11:34 AM Ashton Six <[email protected]> wrote:
>>>
>>>> Hi,
>>>>
>>>> I noticed `new Int8Array(int32.buffer).fill(-1)` is equivalent to
>>>> `int32.fill(-1)` but 10x faster, since [Uint, Int]8.fill() uses memset
>>>> whereas every other implementation of TypedArray.fill() uses a for loop (
>>>> https://github.com/llvm/llvm-project/blob/8bb1dbbf7544eaac3afab8d1f91b71f383dab903/libcxx/include/algorithm#L1987-L2005).
>>>>
>>>> Benchmark: https://jsbench.me/1zl3y8q6q7/1.
>>>>
>>>> Is it worth making this optimisation part of v8 for TypedArray.fill(0),
>>>> Int16Array.fill(-1) and Int32Array.fill(-1)?
>>>>
>>>> Regards,
>>>> Ashton
>>>>
>>>> --
>>>> --
>>>
>>>
--
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