mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2024-12-29 17:23:36 +00:00
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>
This commit is contained in:
Borislav Petkov
H. Peter Anvin
parent
1527bc8b92
commit
d61931d89b
@ -238,6 +238,11 @@ config X86_32_LAZY_GS
|
||||
def_bool y
|
||||
depends on X86_32 && !CC_STACKPROTECTOR
|
||||
|
||||
config ARCH_HWEIGHT_CFLAGS
|
||||
string
|
||||
default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
|
||||
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
|
||||
|
||||
config KTIME_SCALAR
|
||||
def_bool X86_32
|
||||
source "init/Kconfig"
|
||||
|
||||
@ -39,9 +39,6 @@
|
||||
#define LOCK_PREFIX ""
|
||||
#endif
|
||||
|
||||
/* This must be included *after* the definition of LOCK_PREFIX */
|
||||
#include <asm/cpufeature.h>
|
||||
|
||||
struct alt_instr {
|
||||
u8 *instr; /* original instruction */
|
||||
u8 *replacement;
|
||||
@ -95,6 +92,12 @@ static inline int alternatives_text_reserved(void *start, void *end)
|
||||
"663:\n\t" newinstr "\n664:\n" /* replacement */ \
|
||||
".previous"
|
||||
|
||||
/*
|
||||
* This must be included *after* the definition of ALTERNATIVE due to
|
||||
* <asm/arch_hweight.h>
|
||||
*/
|
||||
#include <asm/cpufeature.h>
|
||||
|
||||
/*
|
||||
* Alternative instructions for different CPU types or capabilities.
|
||||
*
|
||||
|
||||
59
arch/x86/include/asm/arch_hweight.h
Normal file
59
arch/x86/include/asm/arch_hweight.h
Normal file
@ -0,0 +1,59 @@
|
||||
#ifndef _ASM_X86_HWEIGHT_H
|
||||
#define _ASM_X86_HWEIGHT_H
|
||||
|
||||
#ifdef CONFIG_64BIT
|
||||
/* popcnt %rdi, %rax */
|
||||
#define POPCNT ".byte 0xf3,0x48,0x0f,0xb8,0xc7"
|
||||
#define REG_IN "D"
|
||||
#define REG_OUT "a"
|
||||
#else
|
||||
/* popcnt %eax, %eax */
|
||||
#define POPCNT ".byte 0xf3,0x0f,0xb8,0xc0"
|
||||
#define REG_IN "a"
|
||||
#define REG_OUT "a"
|
||||
#endif
|
||||
|
||||
/*
|
||||
* __sw_hweightXX are called from within the alternatives below
|
||||
* and callee-clobbered registers need to be taken care of. See
|
||||
* ARCH_HWEIGHT_CFLAGS in <arch/x86/Kconfig> for the respective
|
||||
* compiler switches.
|
||||
*/
|
||||
static inline unsigned int __arch_hweight32(unsigned int w)
|
||||
{
|
||||
unsigned int res = 0;
|
||||
|
||||
asm (ALTERNATIVE("call __sw_hweight32", POPCNT, X86_FEATURE_POPCNT)
|
||||
: "="REG_OUT (res)
|
||||
: REG_IN (w));
|
||||
|
||||
return res;
|
||||
}
|
||||
|
||||
static inline unsigned int __arch_hweight16(unsigned int w)
|
||||
{
|
||||
return __arch_hweight32(w & 0xffff);
|
||||
}
|
||||
|
||||
static inline unsigned int __arch_hweight8(unsigned int w)
|
||||
{
|
||||
return __arch_hweight32(w & 0xff);
|
||||
}
|
||||
|
||||
static inline unsigned long __arch_hweight64(__u64 w)
|
||||
{
|
||||
unsigned long res = 0;
|
||||
|
||||
#ifdef CONFIG_X86_32
|
||||
return __arch_hweight32((u32)w) +
|
||||
__arch_hweight32((u32)(w >> 32));
|
||||
#else
|
||||
asm (ALTERNATIVE("call __sw_hweight64", POPCNT, X86_FEATURE_POPCNT)
|
||||
: "="REG_OUT (res)
|
||||
: REG_IN (w));
|
||||
#endif /* CONFIG_X86_32 */
|
||||
|
||||
return res;
|
||||
}
|
||||
|
||||
#endif
|
||||
@ -444,7 +444,9 @@ static inline int fls(int x)
|
||||
|
||||
#define ARCH_HAS_FAST_MULTIPLIER 1
|
||||
|
||||
#include <asm-generic/bitops/hweight.h>
|
||||
#include <asm/arch_hweight.h>
|
||||
|
||||
#include <asm-generic/bitops/const_hweight.h>
|
||||
|
||||
#endif /* __KERNEL__ */
|
||||
|
||||
|
||||
@ -3,9 +3,23 @@
|
||||
|
||||
#include <asm/types.h>
|
||||
|
||||
extern unsigned int __arch_hweight32(unsigned int w);
|
||||
extern unsigned int __arch_hweight16(unsigned int w);
|
||||
extern unsigned int __arch_hweight8(unsigned int w);
|
||||
extern unsigned long __arch_hweight64(__u64 w);
|
||||
inline unsigned int __arch_hweight32(unsigned int w)
|
||||
{
|
||||
return __sw_hweight32(w);
|
||||
}
|
||||
|
||||
inline unsigned int __arch_hweight16(unsigned int w)
|
||||
{
|
||||
return __sw_hweight16(w);
|
||||
}
|
||||
|
||||
inline unsigned int __arch_hweight8(unsigned int w)
|
||||
{
|
||||
return __sw_hweight8(w);
|
||||
}
|
||||
|
||||
inline unsigned long __arch_hweight64(__u64 w)
|
||||
{
|
||||
return __sw_hweight64(w);
|
||||
}
|
||||
#endif /* _ASM_GENERIC_BITOPS_HWEIGHT_H_ */
|
||||
|
||||
@ -39,7 +39,10 @@ lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
|
||||
lib-$(CONFIG_GENERIC_FIND_FIRST_BIT) += find_next_bit.o
|
||||
lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o
|
||||
obj-$(CONFIG_GENERIC_FIND_LAST_BIT) += find_last_bit.o
|
||||
|
||||
CFLAGS_hweight.o = $(subst $(quote),,$(CONFIG_ARCH_HWEIGHT_CFLAGS))
|
||||
obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
|
||||
|
||||
obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o
|
||||
obj-$(CONFIG_BTREE) += btree.o
|
||||
obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
|
||||
|
||||
@ -9,7 +9,7 @@
|
||||
* The Hamming Weight of a number is the total number of bits set in it.
|
||||
*/
|
||||
|
||||
unsigned int __arch_hweight32(unsigned int w)
|
||||
unsigned int __sw_hweight32(unsigned int w)
|
||||
{
|
||||
#ifdef ARCH_HAS_FAST_MULTIPLIER
|
||||
w -= (w >> 1) & 0x55555555;
|
||||
@ -24,30 +24,30 @@ unsigned int __arch_hweight32(unsigned int w)
|
||||
return (res + (res >> 16)) & 0x000000FF;
|
||||
#endif
|
||||
}
|
||||
EXPORT_SYMBOL(__arch_hweight32);
|
||||
EXPORT_SYMBOL(__sw_hweight32);
|
||||
|
||||
unsigned int __arch_hweight16(unsigned int w)
|
||||
unsigned int __sw_hweight16(unsigned int w)
|
||||
{
|
||||
unsigned int res = w - ((w >> 1) & 0x5555);
|
||||
res = (res & 0x3333) + ((res >> 2) & 0x3333);
|
||||
res = (res + (res >> 4)) & 0x0F0F;
|
||||
return (res + (res >> 8)) & 0x00FF;
|
||||
}
|
||||
EXPORT_SYMBOL(__arch_hweight16);
|
||||
EXPORT_SYMBOL(__sw_hweight16);
|
||||
|
||||
unsigned int __arch_hweight8(unsigned int w)
|
||||
unsigned int __sw_hweight8(unsigned int w)
|
||||
{
|
||||
unsigned int res = w - ((w >> 1) & 0x55);
|
||||
res = (res & 0x33) + ((res >> 2) & 0x33);
|
||||
return (res + (res >> 4)) & 0x0F;
|
||||
}
|
||||
EXPORT_SYMBOL(__arch_hweight8);
|
||||
EXPORT_SYMBOL(__sw_hweight8);
|
||||
|
||||
unsigned long __arch_hweight64(__u64 w)
|
||||
unsigned long __sw_hweight64(__u64 w)
|
||||
{
|
||||
#if BITS_PER_LONG == 32
|
||||
return __arch_hweight32((unsigned int)(w >> 32)) +
|
||||
__arch_hweight32((unsigned int)w);
|
||||
return __sw_hweight32((unsigned int)(w >> 32)) +
|
||||
__sw_hweight32((unsigned int)w);
|
||||
#elif BITS_PER_LONG == 64
|
||||
#ifdef ARCH_HAS_FAST_MULTIPLIER
|
||||
w -= (w >> 1) & 0x5555555555555555ul;
|
||||
@ -64,4 +64,4 @@ unsigned long __arch_hweight64(__u64 w)
|
||||
#endif
|
||||
#endif
|
||||
}
|
||||
EXPORT_SYMBOL(__arch_hweight64);
|
||||
EXPORT_SYMBOL(__sw_hweight64);
|
||||
|
||||
@ -245,3 +245,7 @@ quiet_cmd_lzo = LZO $@
|
||||
cmd_lzo = (cat $(filter-out FORCE,$^) | \
|
||||
lzop -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
|
||||
(rm -f $@ ; false)
|
||||
|
||||
# misc stuff
|
||||
# ---------------------------------------------------------------------------
|
||||
quote:="
|
||||
|
||||
Loading…
Reference in New Issue
Block a user