diff options
author | Ken Steele <ken@tilera.com> | 2013-08-01 15:55:07 -0400 |
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committer | Chris Metcalf <cmetcalf@tilera.com> | 2013-08-01 20:08:51 -0400 |
commit | 5916700c768803546b6fe7d093dcba40d22fcf57 (patch) | |
tree | 07bbeb368b246e82ad23c6af151f4408f7be1cb0 /arch/tile/lib | |
parent | c53c70a90fdce3e7a53a0412abf7cc2b2a645988 (diff) |
tile: optimize strnlen using SIMD instructions
Using strlen as a model, add length checking to create strnlen.
Signed-off-by: Ken Steele <ken@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/lib')
-rw-r--r-- | arch/tile/lib/Makefile | 2 | ||||
-rw-r--r-- | arch/tile/lib/strnlen_32.c | 47 | ||||
-rw-r--r-- | arch/tile/lib/strnlen_64.c | 48 |
3 files changed, 96 insertions, 1 deletions
diff --git a/arch/tile/lib/Makefile b/arch/tile/lib/Makefile index 985f5985823..5d844374b2b 100644 --- a/arch/tile/lib/Makefile +++ b/arch/tile/lib/Makefile @@ -4,7 +4,7 @@ lib-y = cacheflush.o checksum.o cpumask.o delay.o uaccess.o \ memmove.o memcpy_$(BITS).o memchr_$(BITS).o memset_$(BITS).o \ - strchr_$(BITS).o strlen_$(BITS).o + strchr_$(BITS).o strlen_$(BITS).o strnlen_$(BITS).o ifeq ($(CONFIG_TILEGX),y) CFLAGS_REMOVE_memcpy_user_64.o = -fno-omit-frame-pointer diff --git a/arch/tile/lib/strnlen_32.c b/arch/tile/lib/strnlen_32.c new file mode 100644 index 00000000000..1434141d9e0 --- /dev/null +++ b/arch/tile/lib/strnlen_32.c @@ -0,0 +1,47 @@ +/* + * Copyright 2013 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program 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, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/module.h> + +size_t strnlen(const char *s, size_t count) +{ + /* Get an aligned pointer. */ + const uintptr_t s_int = (uintptr_t) s; + const uint32_t *p = (const uint32_t *)(s_int & -4); + size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1)); + size_t len; + uint32_t v, bits; + + /* Avoid page fault risk by not reading any bytes when count is 0. */ + if (count == 0) + return 0; + + /* Read first word, but force bytes before the string to be nonzero. */ + v = *p | ((1 << ((s_int << 3) & 31)) - 1); + + while ((bits = __insn_seqb(v, 0)) == 0) { + if (bytes_read >= count) { + /* Read COUNT bytes and didn't find the terminator. */ + return count; + } + v = *++p; + bytes_read += sizeof(v); + } + + len = ((const char *) p) + (__insn_ctz(bits) >> 3) - s; + return (len < count ? len : count); +} +EXPORT_SYMBOL(strnlen); diff --git a/arch/tile/lib/strnlen_64.c b/arch/tile/lib/strnlen_64.c new file mode 100644 index 00000000000..2e8de6a5136 --- /dev/null +++ b/arch/tile/lib/strnlen_64.c @@ -0,0 +1,48 @@ +/* + * Copyright 2013 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program 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, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/module.h> +#include "string-endian.h" + +size_t strnlen(const char *s, size_t count) +{ + /* Get an aligned pointer. */ + const uintptr_t s_int = (uintptr_t) s; + const uint64_t *p = (const uint64_t *)(s_int & -8); + size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1)); + size_t len; + uint64_t v, bits; + + /* Avoid page fault risk by not reading any bytes when count is 0. */ + if (count == 0) + return 0; + + /* Read and MASK the first word. */ + v = *p | MASK(s_int); + + while ((bits = __insn_v1cmpeqi(v, 0)) == 0) { + if (bytes_read >= count) { + /* Read COUNT bytes and didn't find the terminator. */ + return count; + } + v = *++p; + bytes_read += sizeof(v); + } + + len = ((const char *) p) + (CFZ(bits) >> 3) - s; + return (len < count ? len : count); +} +EXPORT_SYMBOL(strnlen); |