On Sun, Apr 03, 2022 at 02:42:18PM +0200, Bastian Blank wrote: > On Sun, Apr 03, 2022 at 02:17:15PM +0300, Adrian Bunk wrote: > > SIMDe (or similar approaches) could be used to build variant(s) of the > > library that have compile-time emulation of SIMD instructions in the > > lower baseline builds of vectorscan. > > But why? Who in their right mind would ever try to use those aweful > slow implementations?
There are often usecases where speed is critical and usecases where speed is not that important. E.g. one of the versions of the regex library Adam memtioned as example is being used by rspamd. On a busy mailserver the performance of the regex library might be critical, for filtering your personal emails an awful slow implementation might still be fast enough that you don't care. In areas like multimedia it is common that you end up having gazillions of libraries linked and loaded you might never use. E.g. a program that uses FFmpeg for mp3 decoding is also indirectly linked with several libraries for video encoding. If the whole library is compiled with some -msse or -march, then starting the program might fail due to unsupported instructions the compiler generated in the init function of a library you wouldn't have used. > Bastian cu Adrian
