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| author |   Borislav Petkov <borislav.petkov@amd.com> | 2010-03-05 17:34:46 +0100 |
|---|---|---|
| committer |   H. Peter Anvin <hpa@zytor.com> | 2010-04-06 15:52:11 -0700 |
| commit | d61931d89be506372d01a90d1755f6d0a9fafe2d (patch) | |
| tree | 652c34238edcb6c558163abc3cd9d6ce7c5f91a5 /include/linux/bitops.h | |
| parent | bitops: Optimize hweight() by making use of compile-time evaluation (diff) | |
| download | wireguard-linux-d61931d89be506372d01a90d1755f6d0a9fafe2d.tar.xz wireguard-linux-d61931d89be506372d01a90d1755f6d0a9fafe2d.zip | |
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>
Diffstat (limited to 'include/linux/bitops.h')
0 files changed, 0 insertions, 0 deletions