[llvm-dev] UTF-8 conversion speed

Bruce Hoult via llvm-dev llvm-dev at lists.llvm.org
Tue Oct 2 15:44:28 PDT 2018


It may not be in llvm, but it is in Android. I did NEON versions of UTF
functions in H2 2014 and they've been in Samsung's Android versions for
several years, making single digit percentage speedups in benchmarks.

On Wed, Oct 3, 2018 at 10:58 AM, Friedman, Eli via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> On 10/2/2018 2:27 PM, via llvm-dev wrote:
>
>> At CPPcon last week, I saw a talk by Bob Steagall called
>> "Fast Conversion From UTF-8 with C++, DFAs, and SSE Intrinsics."
>> Part of this talk included data from a half-dozen or so conversion
>> libraries... one of which was labeled "LLVM".
>>
>> The LLVM converters were invariably the slowest.
>>
>
> UTF conversion is not on any hot paths, as far as I know, so nobody has
> spent any time optimizing it.  If you're interested in the history of the
> LLVM code, see https://reviews.llvm.org/rC68208 ; it's mostly untouched
> since then, except for a few bugfixes.
>
> -Eli
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project
>
>
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