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authorBorislav Petkov <borislav.petkov@amd.com>2010-03-05 11:34:46 -0500
committerH. Peter Anvin <hpa@zytor.com>2010-04-06 18:52:11 -0400
commitd61931d89be506372d01a90d1755f6d0a9fafe2d (patch)
tree652c34238edcb6c558163abc3cd9d6ce7c5f91a5 /arch/x86/Kconfig
parent1527bc8b928dd1399c3d3467dd47d9ede210978a (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>
Diffstat (limited to 'arch/x86/Kconfig')
-rw-r--r--arch/x86/Kconfig5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0eacb1ffb421..89d8c54cdd37 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -238,6 +238,11 @@ config X86_32_LAZY_GS
238 def_bool y 238 def_bool y
239 depends on X86_32 && !CC_STACKPROTECTOR 239 depends on X86_32 && !CC_STACKPROTECTOR
240 240
241config ARCH_HWEIGHT_CFLAGS
242 string
243 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
244 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
245
241config KTIME_SCALAR 246config KTIME_SCALAR
242 def_bool X86_32 247 def_bool X86_32
243source "init/Kconfig" 248source "init/Kconfig"