Messages in this thread Patch in this message | | | Date | Tue, 1 Apr 2008 17:47:57 +0200 | From | Alexander van Heukelum <> | Subject | [PATCH] x86: remove x86-specific implementations of find_first_bit |
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[PATCH] x86: remove x86-specific implementations of find_first_bit
x86 has been switched to the generic versions of find_first_bit and find_first_zero_bit, but the original versions were retained. This patch just removes the now unused x86-specific versions.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
--- arch/x86/lib/Makefile | 1 - arch/x86/lib/bitops_64.c | 109 ------------------------------------------- include/asm-x86/bitops_32.h | 58 ----------------------- include/asm-x86/bitops_64.h | 23 --------- 4 files changed, 0 insertions(+), 191 deletions(-) delete mode 100644 arch/x86/lib/bitops_64.c
This patch should of course wait until it is decided if the generic version is good enough to replace the x86-specific ones. I hacked together a benchmark that people can run on different machines. It can be downloaded from:
http://heukelum.fastmail.fm/find_first_bit
Greetings, Alexander
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index 4360932..76f60f5 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -21,7 +21,6 @@ else lib-y += csum-partial_64.o csum-copy_64.o csum-wrappers_64.o lib-y += thunk_64.o clear_page_64.o copy_page_64.o - lib-y += bitops_64.o lib-y += memmove_64.o memset_64.o lib-y += copy_user_64.o rwlock_64.o copy_user_nocache_64.o endif diff --git a/arch/x86/lib/bitops_64.c b/arch/x86/lib/bitops_64.c deleted file mode 100644 index 568467d..0000000 --- a/arch/x86/lib/bitops_64.c +++ /dev/null @@ -1,109 +0,0 @@ -#ifndef CONFIG_GENERIC_FIND_FIRST_BIT -#include <linux/bitops.h> - -#undef find_first_zero_bit -#undef find_first_bit - -static inline long -__find_first_zero_bit(const unsigned long * addr, unsigned long size) -{ - long d0, d1, d2; - long res; - - /* - * We must test the size in words, not in bits, because - * otherwise incoming sizes in the range -63..-1 will not run - * any scasq instructions, and then the flags used by the je - * instruction will have whatever random value was in place - * before. Nobody should call us like that, but - * find_next_zero_bit() does when offset and size are at the - * same word and it fails to find a zero itself. - */ - size += 63; - size >>= 6; - if (!size) - return 0; - asm volatile( - " repe; scasq\n" - " je 1f\n" - " xorq -8(%%rdi),%%rax\n" - " subq $8,%%rdi\n" - " bsfq %%rax,%%rdx\n" - "1: subq %[addr],%%rdi\n" - " shlq $3,%%rdi\n" - " addq %%rdi,%%rdx" - :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2) - :"0" (0ULL), "1" (size), "2" (addr), "3" (-1ULL), - [addr] "S" (addr) : "memory"); - /* - * Any register would do for [addr] above, but GCC tends to - * prefer rbx over rsi, even though rsi is readily available - * and doesn't have to be saved. - */ - return res; -} - -/** - * find_first_zero_bit - find the first zero bit in a memory region - * @addr: The address to start the search at - * @size: The maximum size to search - * - * Returns the bit-number of the first zero bit, not the number of the byte - * containing a bit. - */ -long find_first_zero_bit(const unsigned long * addr, unsigned long size) -{ - return __find_first_zero_bit (addr, size); -} - -static inline long -__find_first_bit(const unsigned long * addr, unsigned long size) -{ - long d0, d1; - long res; - - /* - * We must test the size in words, not in bits, because - * otherwise incoming sizes in the range -63..-1 will not run - * any scasq instructions, and then the flags used by the jz - * instruction will have whatever random value was in place - * before. Nobody should call us like that, but - * find_next_bit() does when offset and size are at the same - * word and it fails to find a one itself. - */ - size += 63; - size >>= 6; - if (!size) - return 0; - asm volatile( - " repe; scasq\n" - " jz 1f\n" - " subq $8,%%rdi\n" - " bsfq (%%rdi),%%rax\n" - "1: subq %[addr],%%rdi\n" - " shlq $3,%%rdi\n" - " addq %%rdi,%%rax" - :"=a" (res), "=&c" (d0), "=&D" (d1) - :"0" (0ULL), "1" (size), "2" (addr), - [addr] "r" (addr) : "memory"); - return res; -} - -/** - * find_first_bit - find the first set bit in a memory region - * @addr: The address to start the search at - * @size: The maximum size to search - * - * Returns the bit-number of the first set bit, not the number of the byte - * containing a bit. - */ -long find_first_bit(const unsigned long * addr, unsigned long size) -{ - return __find_first_bit(addr,size); -} - -#include <linux/module.h> - -EXPORT_SYMBOL(find_first_bit); -EXPORT_SYMBOL(find_first_zero_bit); -#endif diff --git a/include/asm-x86/bitops_32.h b/include/asm-x86/bitops_32.h index ba2c0de..2e86302 100644 --- a/include/asm-x86/bitops_32.h +++ b/include/asm-x86/bitops_32.h @@ -4,64 +4,6 @@ /* * Copyright 1992, Linus Torvalds. */ - -#ifndef CONFIG_GENERIC_FIND_FIRST_BIT -/** - * find_first_zero_bit - find the first zero bit in a memory region - * @addr: The address to start the search at - * @size: The maximum size to search - * - * Returns the bit number of the first zero bit, not the number of the byte - * containing a bit. - */ -static inline int find_first_zero_bit(const unsigned long *addr, unsigned size) -{ - int d0, d1, d2; - int res; - - if (!size) - return 0; - /* This looks at memory. - * Mark it volatile to tell gcc not to move it around - */ - asm volatile("movl $-1,%%eax\n\t" - "xorl %%edx,%%edx\n\t" - "repe; scasl\n\t" - "je 1f\n\t" - "xorl -4(%%edi),%%eax\n\t" - "subl $4,%%edi\n\t" - "bsfl %%eax,%%edx\n" - "1:\tsubl %%ebx,%%edi\n\t" - "shll $3,%%edi\n\t" - "addl %%edi,%%edx" - : "=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2) - : "1" ((size + 31) >> 5), "2" (addr), - "b" (addr) : "memory"); - return res; -} - -/** - * find_first_bit - find the first set bit in a memory region - * @addr: The address to start the search at - * @size: The maximum size to search - * - * Returns the bit number of the first set bit, not the number of the byte - * containing a bit. - */ -static inline unsigned find_first_bit(const unsigned long *addr, unsigned size) -{ - unsigned x = 0; - - while (x < size) { - unsigned long val = *addr++; - if (val) - return __ffs(val) + x; - x += sizeof(*addr) << 3; - } - return x; -} -#endif - #ifdef __KERNEL__ #include <asm-generic/bitops/sched.h> diff --git a/include/asm-x86/bitops_64.h b/include/asm-x86/bitops_64.h index 4081d7e..cb23122 100644 --- a/include/asm-x86/bitops_64.h +++ b/include/asm-x86/bitops_64.h @@ -4,29 +4,6 @@ /* * Copyright 1992, Linus Torvalds. */ - -#ifndef CONFIG_GENERIC_FIND_FIRST_BIT -extern long find_first_zero_bit(const unsigned long *addr, unsigned long size); -extern long find_first_bit(const unsigned long *addr, unsigned long size); - -/* return index of first bet set in val or max when no bit is set */ -static inline long __scanbit(unsigned long val, unsigned long max) -{ - asm("bsfq %1,%0 ; cmovz %2,%0" : "=&r" (val) : "r" (val), "r" (max)); - return val; -} - -#define find_first_bit(addr, size) \ - ((__builtin_constant_p((size)) && (size) <= BITS_PER_LONG \ - ? (__scanbit(*(unsigned long *)(addr), (size))) \ - : find_first_bit((addr), (size)))) - -#define find_first_zero_bit(addr, size) \ - ((__builtin_constant_p((size)) && (size) <= BITS_PER_LONG \ - ? (__scanbit(~*(unsigned long *)(addr), (size))) \ - : find_first_zero_bit((addr), (size)))) -#endif - static inline void set_bit_string(unsigned long *bitmap, unsigned long i, int len) { -- 1.5.2.5
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