Jan Beulich 5870661c09 x86: Prefer TZCNT over BFS ... Following a relatively recent compiler change, make use of the fact that for non-zero input BSF and TZCNT produce the same result, and that CPUs not knowing of TZCNT will treat the instruction as BSF (i.e. ignore what looks like a REP prefix to them). The assumption here is that TZCNT would never have worse performance than BSF. For the moment, only do this when the respective generic-CPU option is selected (as there are no specific-CPU options covering the CPUs supporting TZCNT), and don't do that when size optimization was requested. Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/504DEA1B020000780009A277@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2012-09-13 17:44:01 +02:00
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asm	x86: Prefer TZCNT over BFS	2012-09-13 17:44:01 +02:00