d61931d89be506372d01a90d1755f6d0a9fafe2d - linux

commit	d61931d89be506372d01a90d1755f6d0a9fafe2d	[log] [tgz]
author	Borislav Petkov <borislav.petkov@amd.com>	Fri Mar 05 17:34:46 2010 +0100
committer	H. Peter Anvin <hpa@zytor.com>	Tue Apr 06 15:52:11 2010 -0700
tree	652c34238edcb6c558163abc3cd9d6ce7c5f91a5
parent	1527bc8b928dd1399c3d3467dd47d9ede210978a [diff]

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>

arch/x86/Kconfig[diff]
arch/x86/include/asm/alternative.h[diff]
arch/x86/include/asm/arch_hweight.h[Added - diff]
arch/x86/include/asm/bitops.h[diff]
include/asm-generic/bitops/arch_hweight.h[diff]
lib/Makefile[diff]
lib/hweight.c[diff]
scripts/Makefile.lib[diff]

8 files changed

tree: 652c34238edcb6c558163abc3cd9d6ce7c5f91a5