[swift-users] Performance critical code in Swift

[Jens Persson]

There's no reason why writing data to disk should be slower in Swift than
in C/C++.

(For the name and location properties, I assume you want to save Strings, a
sequence of characters or something rather than just the value of the
UnsafePointer<UInt8>.)

On Sat, Oct 1, 2016 at 11:22 PM, Игорь Никитин <devnikor at icloud.com> wrote:

> I got it. Thanks for your tips!
>
> 2 окт. 2016 г., в 0:13, Jens Persson <jens at bitcycle.com> написал(а):
>
> You could write some examples in both C and Swift in order to gain
> experience in how to write your Swift code so that it will (probably) run
> as fast as (or faster than) your corresponding C code.
>
> I've done this for a number of different performance critical things and
> it is often possible to get the Swift version as fast as the C version.
>
> (If you find something that is not possible (or unnecessarily cumbersome)
> to write as fast in Swift as in C, you could probably file a
> bug/improvement on bugs.swift.org. I did this some time ago when I
> noticed that Swift's optimizer missed an opportunity to unroll loops in a
> certain situation and it turned out that a fix/optimizer-improvement was
> already on its way.)
>
> You must of course profile/microbenchmark your code in some meaningful
> way, setting all relevant compiler flags for both C and Swift, preventing
> dead code elimination, measuring average or perhaps median times of lots of
> tests, making sure what should and shouldn't be statically knowable, etc.
>
> In Swift you probably want -O -whole-module-optimization, and (rarely) you
> might want/need to disable safety checks.
>
> /Jens
>
>
>
> On Sat, Oct 1, 2016 at 10:33 PM, Daniel Dunbar via swift-users <
> swift-users at swift.org> wrote:
>
>> Yes, it is possible. Exactly how much use of Unsafe style idioms and
>> other performance-focused "workarounds" it requires depends a lot on the
>> code in question. Can you say more about your problem area?
>>
>>  - Daniel
>>
>> > On Oct 1, 2016, at 1:30 PM, Игорь Никитин via swift-users <
>> swift-users at swift.org> wrote:
>> >
>> > Hello!
>> > Is it possible for Swift to be as fast as C when writing performance
>> critical code? Of course if using C Standard Library for instead of
>> Foundation (and so on) and getting rid of dynamic dispatch and reference
>> types.
>> > Or I need just to use C?
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>>
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>
>
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