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s390: Provide optimized __arch_hweight*() implementations

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Make use of the popcnt instruction to provide optimized __arch_hweight*()
implementations. The generated code is shorter and avoids rather expensive
functions calls.

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2024-06-09 21:02:19 +02:00 committed by Alexander Gordeev
parent 447360d75c
commit 7c67928648
3 changed files with 79 additions and 2 deletions
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2
arch/s390/Kconfig
View File

@ -21,7 +21,7 @@ config ARCH_PROC_KCORE_TEXT
def_bool y
config GENERIC_HWEIGHT
def_bool y
def_bool !HAVE_MARCH_Z196_FEATURES
config GENERIC_BUG
def_bool y if BUG

76
arch/s390/include/asm/arch_hweight.h Normal file
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@ -0,0 +1,76 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_S390_ARCH_HWEIGHT_H
#define _ASM_S390_ARCH_HWEIGHT_H
#include <linux/types.h>
static __always_inline unsigned long popcnt_z196(unsigned long w)
{
unsigned long cnt;
asm volatile(".insn rrf,0xb9e10000,%[cnt],%[w],0,0"
: [cnt] "=d" (cnt)
: [w] "d" (w)
: "cc");
return cnt;
}
static __always_inline unsigned long popcnt_z15(unsigned long w)
{
unsigned long cnt;
asm volatile(".insn rrf,0xb9e10000,%[cnt],%[w],8,0"
: [cnt] "=d" (cnt)
: [w] "d" (w)
: "cc");
return cnt;
}
static __always_inline unsigned long __arch_hweight64(__u64 w)
{
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z15_FEATURES))
return popcnt_z15(w);
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z196_FEATURES)) {
w = popcnt_z196(w);
w += w >> 32;
w += w >> 16;
w += w >> 8;
return w & 0xff;
}
return __sw_hweight64(w);
}
static __always_inline unsigned int __arch_hweight32(unsigned int w)
{
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z15_FEATURES))
return popcnt_z15(w);
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z196_FEATURES)) {
w = popcnt_z196(w);
w += w >> 16;
w += w >> 8;
return w & 0xff;
}
return __sw_hweight32(w);
}
static __always_inline unsigned int __arch_hweight16(unsigned int w)
{
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z15_FEATURES))
return popcnt_z15((unsigned short)w);
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z196_FEATURES)) {
w = popcnt_z196(w);
w += w >> 8;
return w & 0xff;
}
return __sw_hweight16(w);
}
static __always_inline unsigned int __arch_hweight8(unsigned int w)
{
if (IS_ENABLED(CONFIG_HAVE_MARCH_Z196_FEATURES))
return popcnt_z196((unsigned char)w);
return __sw_hweight8(w);
}
#endif /* _ASM_S390_ARCH_HWEIGHT_H */

3
arch/s390/include/asm/bitops.h
View File

@ -379,8 +379,9 @@ static inline int fls(unsigned int word)
return fls64(word);
}
#include <asm/arch_hweight.h>
#include <asm-generic/bitops/const_hweight.h>
#include <asm-generic/bitops/ffz.h>
#include <asm-generic/bitops/hweight.h>
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/le.h>
#include <asm-generic/bitops/ext2-atomic-setbit.h>