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Message-ID: <20080401154757.GC26062@mailshack.com>
Date: Tue, 1 Apr 2008 17:47:57 +0200
From: Alexander van Heukelum <heukelum@...lshack.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: Andi Kleen <andi@...stfloor.org>,
LKML <linux-kernel@...r.kernel.org>,
Alexander van Heukelum <heukelum@...tmail.fm>
Subject: [PATCH] x86: remove x86-specific implementations of find_first_bit
[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@...tmail.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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