powerpc: Optimized rawmemchr for POWER9

This version uses vector instructions and is up to 60% faster on medium
matches and up to 90% faster on long matches, compared to the POWER7
version. A few examples:

                            __rawmemchr_power9  __rawmemchr_power7
Length   32, alignment  0:   2.27566             3.77765
Length   64, alignment  2:   2.46231             3.51064
Length 1024, alignment  0:  17.3059             32.6678
This commit is contained in:
Anton Blanchard 2020-05-14 21:49:16 +10:00 committed by Paul E. Murphy
parent 9e38f455a6
commit 765de945ef
5 changed files with 145 additions and 3 deletions

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@ -0,0 +1,107 @@
/* Optimized rawmemchr implementation for PowerPC64/POWER9.
Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#ifndef RAWMEMCHR
# define RAWMEMCHR __rawmemchr
#endif
/* Implements the function
int [r3] rawmemchr (void *s [r3], int c [r4])
The implementation can load bytes past a matching byte, but only
up to the next 16B boundary, so it never crosses a page. */
.machine power9
ENTRY_TOCLESS (RAWMEMCHR, 4)
CALL_MCOUNT 2
xori r5,r4,0xff
mtvsrd v18+32,r4 /* matching char in v18 */
mtvsrd v19+32,r5 /* non matching char in v19 */
vspltb v18,v18,7 /* replicate */
vspltb v19,v19,7 /* replicate */
neg r5,r3
rldicl r9,r5,0,60 /* How many bytes to get source 16B aligned? */
/* Align data and fill bytes not loaded with non matching char */
lvx v0,0,r3
lvsr v1,0,r3
vperm v0,v19,v0,v1
vcmpequb. v6,v0,v18 /* 0xff if byte matches, 0x00 otherwise */
beq cr6,L(aligned)
vctzlsbb r0,v6
add r3,r3,r0
blr
L(aligned):
add r3,r3,r9
L(loop):
lxv v0+32,0(r3)
vcmpequb. v6,v0,v18 /* 0xff if byte matches, 0x00 otherwise */
bne cr6,L(tail1)
lxv v0+32,16(r3)
vcmpequb. v6,v0,v18 /* 0xff if byte matches, 0x00 otherwise */
bne cr6,L(tail2)
lxv v0+32,32(r3)
vcmpequb. v6,v0,v18 /* 0xff if byte matches, 0x00 otherwise */
bne cr6,L(tail3)
lxv v0+32,48(r3)
vcmpequb. v6,v0,v18 /* 0xff if byte matches, 0x00 otherwise */
bne cr6,L(tail4)
addi r3,r3,64
b L(loop)
L(tail1):
vctzlsbb r0,v6
add r3,r3,r0
blr
L(tail2):
vctzlsbb r0,v6
add r3,r3,r0
addi r3,r3,16
blr
L(tail3):
vctzlsbb r0,v6
add r3,r3,r0
addi r3,r3,32
blr
L(tail4):
vctzlsbb r0,v6
add r3,r3,r0
addi r3,r3,48
blr
END (RAWMEMCHR)
weak_alias (__rawmemchr,rawmemchr)
libc_hidden_builtin_def (__rawmemchr)

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@ -32,7 +32,8 @@ sysdep_routines += memcpy-power8-cached memcpy-power7 memcpy-a2 memcpy-power6 \
strncase-power8
ifneq (,$(filter %le,$(config-machine)))
sysdep_routines += strcmp-power9 strncmp-power9 strcpy-power9 stpcpy-power9
sysdep_routines += strcmp-power9 strncmp-power9 strcpy-power9 stpcpy-power9 \
rawmemchr-power9
endif
CFLAGS-strncase-power7.c += -mcpu=power7 -funroll-loops
CFLAGS-strncase_l-power7.c += -mcpu=power7 -funroll-loops

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@ -216,6 +216,11 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
/* Support sysdeps/powerpc/powerpc64/multiarch/rawmemchr.c. */
IFUNC_IMPL (i, name, rawmemchr,
#ifdef __LITTLE_ENDIAN__
IFUNC_IMPL_ADD (array, i, rawmemchr,
hwcap2 & PPC_FEATURE2_ARCH_3_00,
__rawmemchr_power9)
#endif
IFUNC_IMPL_ADD (array, i, rawmemchr,
hwcap & PPC_FEATURE_HAS_VSX,
__rawmemchr_power7)

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@ -0,0 +1,21 @@
/* Optimized rawmemchr implementation for PowerPC64/POWER9.
Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#define RAWMEMCHR __rawmemchr_power9
#include <sysdeps/powerpc/powerpc64/le/power9/rawmemchr.S>

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@ -24,13 +24,21 @@
extern __typeof (__rawmemchr) __rawmemchr_ppc attribute_hidden;
extern __typeof (__rawmemchr) __rawmemchr_power7 attribute_hidden;
# ifdef __LITTLE_ENDIAN__
extern __typeof (__rawmemchr) __rawmemchr_power9 attribute_hidden;
# endif
# undef __rawmemchr
/* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
ifunc symbol properly. */
libc_ifunc_redirected (__redirect___rawmemchr, __rawmemchr,
(hwcap & PPC_FEATURE_HAS_VSX)
? __rawmemchr_power7
# ifdef __LITTLE_ENDIAN__
(hwcap2 & PPC_FEATURE2_ARCH_3_00)
? __rawmemchr_power9 :
# endif
(hwcap & PPC_FEATURE_HAS_VSX)
? __rawmemchr_power7
: __rawmemchr_ppc);
weak_alias (__rawmemchr, rawmemchr)