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authorBorislav Petkov <borislav.petkov@amd.com>2010-03-05 17:34:46 +0100
committerH. Peter Anvin <hpa@zytor.com>2010-04-06 15:52:11 -0700
commitd61931d89be506372d01a90d1755f6d0a9fafe2d (patch)
tree652c34238edcb6c558163abc3cd9d6ce7c5f91a5 /include/linux/bitops.h
parent1527bc8b928dd1399c3d3467dd47d9ede210978a (diff)
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x86: Add optimized popcnt variants
Add support for the hardware version of the Hamming weight function, popcnt, present in CPUs which advertize it under CPUID, Function 0x0000_0001_ECX[23]. On CPUs which don't support it, we fallback to the default lib/hweight.c sw versions. A synthetic benchmark comparing popcnt with __sw_hweight64 showed almost a 3x speedup on a F10h machine. Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> LKML-Reference: <20100318112015.GC11152@aftab> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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