-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 02/09/2015 16:55, Jung-uk Kim wrote: > On 02/09/2015 16:08, John Baldwin wrote: >> On Monday, February 09, 2015 09:03:24 PM John Baldwin wrote: >>> Author: jhb Date: Mon Feb 9 21:03:23 2015 New Revision: >>> 278474 URL: https://svnweb.freebsd.org/changeset/base/278474 >>> >>> Log: Use __builtin_popcnt() to implement a BIT_COUNT() >>> operation for bitsets and use this to implement CPU_COUNT() to >>> count the number of CPUs in a cpuset. >>> >>> MFC after: 2 weeks > >> Yes, __builtin_popcnt() works with GCC 4.2. It should also >> allow the compiler to DTRT in userland uses of this if -msse4.2 >> is enabled. > > Back in 2012, when I submitted a similar patch, bde noted > __builtin_popcount*() cannot be used with GCC 4.2 for *kernel* > because it emits a library call. > > http://docs.freebsd.org/cgi/mid.cgi?20121116171923.L1135
BTW, __POPCNT__ macro may be used to detect availability of POPCNT instruction when compiled with Clang. Jung-uk Kim -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJU2S9NAAoJEHyflib82/FGy+kH/20SFWEXK5lSfWxYMvxMp46W ZjOFW46ZefkUHiDLgPcED4oZd4cmX/KNXns3YSO5lwL4JeFsO+mzTKpmV7llPV22 y1/xHChk3Z3BJwq3lzGZmVeT4Cw2T6Mf4f1PCqfMkijDDsVrkEYBeko+QW3gpGjZ BrjH8EmFLDZ78rmPP/Nsbm8HZNEI89NOGBYEw615kA5ibuZZ0L2T6ybcipysDaxe fYpBcIhm58erXIrlNtYeSX6YyZPHMPJBACjkyPEKk8L7eKYR27++VKZGas8flEze 5x/5n9TftKwei2rHXhuogNqClACsLIBkM6a/Y/PNBMDOQ+0OEu6uDr0a63log00= =zY2U -----END PGP SIGNATURE----- _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
