http://d.puremagic.com/issues/show_bug.cgi?id=4046
--- Comment #1 from Don <clugd...@yahoo.com.au> 2011-09-22 06:27:33 PDT --- I'm not sure why the btXX functions (bt, btc, btr, etc) exist at all. Although they are a single instruction, they are MUCH slower than the equivalent code using shifts or AND/OR/XOR. For example, on Core i7 (Sandy Bridge), with a memory operand, they take 6 clock cycles!!!! You can execute 24 integer instructions in that time. On AMD K10, they're even slower. On Pentium 4 they have a latency of EIGHTEEN clock cycles. They're even slow on VIA processors as well -- they're not good anywhere. I think they should be completely removed. There's a case for the intrinsics mentioned in bug 5703, but I think this should be a WONTFIX. To support them would just encourage slow, non-portable code. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------