On Tue, 30 Jul 2024, 06:21 Ehrnsperger, Markus, <markus_ehrnsper...@yahoo.de> wrote:
> On 2024-07-29 12:16, Jonathan Wakely wrote: > > > On Mon, 29 Jul 2024 at 10:45, Jonathan Wakely <jwakely....@gmail.com> > wrote: > >> On Mon, 29 Jul 2024 at 09:42, Ehrnsperger, Markus > >> <markus_ehrnsper...@yahoo.de> wrote: > >>> Hi, > >>> > >>> > >>> I'm attaching two files: > >>> > >>> 1.: to_chars10.h: > >>> > >>> This is intended to be included in libstdc++ / gcc to achieve > performance improvements. It is an implementation of > >>> > >>> to_chars10(char* first, char* last, /* integer-type */ value); > >>> > >>> Parameters are identical to std::to_chars(char* first, char* last, /* > integer-type */ value, int base = 10 ); . It only works for base == 10. > >>> > >>> If it is included in libstdc++, to_chars10(...) could be renamed to > std::to_chars(char* first, char* last, /* integer-type */ value) to > provide an overload for the default base = 10 > >> Thanks for the email. This isn't in the form of a patch that we can > >> accept as-is, although I see that the license is compatible with > >> libstdc++, so if you are looking to contribute it then that could be > >> done either by assigning copyright to the FSF or under the DCO terms. > >> See https://gcc.gnu.org/contribute.html#legal for more details. > >> > >> I haven't looked at the code in detail, but is it a similar approach > >> to https://jk-jeon.github.io/posts/2022/02/jeaiii-algorithm/ ? > >> How does it compare to the performance of that algorithm? > >> > >> I have an incomplete implementation of that algorithm for libstdc++ > >> somewhere, but I haven't looked at it for a while. > > I took a closer look and the reinterpret_casts worried me, so I tried > > your test code with UBsan. There are a number of errors that would > > need to be fixed before we would consider using this code. > > Attached are new versions of to_chars10.cpp, to_chars10.h and the new > file itoa_better_y.h > Thanks! I'll take another look. > Changes: > > - I removed all reinterpret_casts, and tested with -fsanitize=undefined > > - I added itoa_better_y.h from > https://jk-jeon.github.io/posts/2022/02/jeaiii-algorithm/ to the > performance test. > > Note: There is only one line in the benchmark test for itoa_better_y due > to limited features of itoa_better_y: > > Benchmarking random unsigned 32 bit itoa_better_y ... > > > to_chars10.h: Signed-off-by: Markus Ehrnsperger > <markus_ehrnsper...@yahoo.de> > > The other files are only for performance tests. > > > > > > >> > >>> 2.: to_chars10.cpp: > >>> > >>> This is a test program for to_chars10 verifying the correctness of the > results, and measuring the performance. The actual performance improvement > is system dependent, so please test on your own system. > >>> > >>> On my system the performance improvement is about factor two, my > results are: > >>> > >>> > >>> Test int8_t verifying to_chars10 = std::to_chars ... OK > >>> Test uint8_t verifying to_chars10 = std::to_chars ... OK > >>> Test int16_t verifying to_chars10 = std::to_chars ... OK > >>> Test uint16_t verifying to_chars10 = std::to_chars ... OK > >>> Test int32_t verifying to_chars10 = std::to_chars ... OK > >>> Test uint32_t verifying to_chars10 = std::to_chars ... OK > >>> Test int64_t verifying to_chars10 = std::to_chars ... OK > >>> Test uint64_t verifying to_chars10 = std::to_chars ... OK > >>> > >>> Benchmarking test case tested method ... time (lower > is better) > >>> Benchmarking random unsigned 64 bit to_chars10 ... 0.00957 > >>> Benchmarking random unsigned 64 bit std::to_chars ... 0.01854 > >>> Benchmarking random signed 64 bit to_chars10 ... 0.01018 > >>> Benchmarking random signed 64 bit std::to_chars ... 0.02297 > >>> Benchmarking random unsigned 32 bit to_chars10 ... 0.00620 > >>> Benchmarking random unsigned 32 bit std::to_chars ... 0.01275 > >>> Benchmarking random signed 32 bit to_chars10 ... 0.00783 > >>> Benchmarking random signed 32 bit std::to_chars ... 0.01606 > >>> Benchmarking random unsigned 16 bit to_chars10 ... 0.00536 > >>> Benchmarking random unsigned 16 bit std::to_chars ... 0.00871 > >>> Benchmarking random signed 16 bit to_chars10 ... 0.00664 > >>> Benchmarking random signed 16 bit std::to_chars ... 0.01154 > >>> Benchmarking random unsigned 08 bit to_chars10 ... 0.00393 > >>> Benchmarking random unsigned 08 bit std::to_chars ... 0.00626 > >>> Benchmarking random signed 08 bit to_chars10 ... 0.00465 > >>> Benchmarking random signed 08 bit std::to_chars ... 0.01089 > >>> > >>> > >>> Thanks, Markus > >>> > >>> > >>>
