After doing some research, the GCC default __builtin_popcount functions are slower than the FREEBSD versions (roughly 3.5x slower according to some tests I saw online). If someone adds the -mpopcnt compile option, then it means that there is a CPU instruction to perform the task. I think we should do what FREEBSD has done. Only use the built in functions if there is a CPU instruction to execute it.
I have posted a patch to newlib. Kevin Kirspel Electrical Engineer - Sr. Staff Idexx Roswell 235 Hembree Park Drive Roswell GA 30076 Tel: (770)-510-4444 ext. 81642 Direct: (770)-688-1642 Fax: (770)-510-4445 -----Original Message----- From: Sebastian Huber [mailto:sebastian.hu...@embedded-brains.de] Sent: Tuesday, May 16, 2017 9:28 AM To: Kirspel, Kevin <kevin-kirs...@idexx.com>; devel@rtems.org Subject: Re: [PATCH 07/11] Add bitcount inlinesfor RTEMS. These are found in FREEBSDs types.h On 16/05/17 15:18, Kirspel, Kevin wrote: > Sorry. I pulled that header file from memory which these days is losing its > effectiveness. So, should we put the bitcount changes in sys/types.h like > FREEBSD? > > If so, I will submit a patch tonew...@sourceware.org. How long does it take > to get the patch reviewed by the newlib mailing list? Between one day and four weeks. If its not included this week, then we can use the alternative. Please add GCC support for these operations. I think the builtins are available since GCC 3.4.0. -- Sebastian Huber, embedded brains GmbH Address : Dornierstr. 4, D-82178 Puchheim, Germany Phone : +49 89 189 47 41-16 Fax : +49 89 189 47 41-09 E-Mail : sebastian.hu...@embedded-brains.de PGP : Public key available on request. Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG. _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
