[PATCH] D40697: Cache modulo values for the .gnu.hash section.

[Rafael Avila de Espindola via llvm-commits]

Rui Ueyama <ruiu at google.com> writes:

> On Fri, Dec 1, 2017 at 1:41 PM, Rafael Avila de Espindola <
> rafael.espindola at gmail.com> wrote:
>
>> Rui Ueyama via Phabricator <reviews at reviews.llvm.org> writes:
>>
>> > ruiu updated this revision to Diff 125067.
>> > ruiu added a comment.
>> >
>> > - clang-format
>> >
>> > It seems this patch actually makes that test case 2% faster, which
>> > isn't a negligible improvement.
>>
>> Please benchmark more than clang. There is a set of different benchmarks
>> in https://s3-us-west-2.amazonaws.com/linker-tests/lld-speed-test.tar.xz.
>
>
> We don't need to run all these benchmarks as this patch is a micro
> optimization. More precisely, in order to create a hash table for 22212
> symbols,
>
>  - GnuHashTableSection::addSymbols took 60 ms
>  - GnuHashTableSection::writeHashTable took 8 ms.
>
> With this patch it now takes 37 ms and 7 ms, respectively.

I am uncomfortable LGTMing an optimization without a full
benchmark. Specially one that trades memory for speed.

I will benchmark the patch. This will hopefully get better soon with a
bot tracking performance.

Cheers,
Rafael