On Mon, May 30, 2016 at 12:56:27PM +0200, Borislav Petkov wrote: > From: Borislav Petkov <[email protected]> > > People complained about ARCH_HWEIGHT_CFLAGS and how it throws a wrench > into kcov, lto, etc, experimentations. > > Add asm versions for __sw_hweight{32,64}() and do explicit saving and > restoring of clobbered registers. This gets rid of the special calling > convention. We get to call those functions on !X86_FEATURE_POPCNT CPUs. > > We still need to hardcode POPCNT and register operands as some old gas > versions which we support, do not know about POPCNT. > > Btw, remove redundant REX prefix from 32-bit POPCNT because alternatives > can do padding now. > > Suggested-by: "H. Peter Anvin" <[email protected]> > Signed-off-by: Borislav Petkov <[email protected]> > Cc: Andy Lutomirski <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
