Commit Graph

5 Commits

Author SHA1 Message Date
Alexey Dobriyan 890890cb8e x86/i386: Use less assembly in strlen(), speed things up a bit
Current i386 strlen() hardcodes NOT/DEC sequence. DEC is
mentioned to be suboptimal on Core2. So, put only REPNE SCASB
sequence in assembly, compiler can do the rest.

The difference in generated code is like below (MCORE2=y):

	<strlen>:
		push   %edi
		mov    $0xffffffff,%ecx
		mov    %eax,%edi
		xor    %eax,%eax
		repnz scas %es:(%edi),%al
		not    %ecx

	-	dec    %ecx
	-	mov    %ecx,%eax
	+	lea    -0x1(%ecx),%eax

		pop    %edi
		ret

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jan Beulich <JBeulich@suse.com>
Link: http://lkml.kernel.org/r/20111211181319.GA17097@p183.telecom.by
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-12 18:33:42 +01:00
Paolo Ciarrocchi 3492cdf017 x86: coding style fixes to arch/x86/lib/string_32.c
Before:
total: 21 errors, 0 warnings, 237 lines checked

After:
total: 0 errors, 0 warnings, 237 lines checked

paolo@paolo-desktop:~/linux.trees.git$ md5sum /tmp/string_32.o.*
c55d059ef1612b32a8bb2771a72ae0d5  /tmp/string_32.o.after
c55d059ef1612b32a8bb2771a72ae0d5  /tmp/string_32.o.before

Signed-off-by: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-15 16:53:25 +02:00
Paolo Ciarrocchi 8cf36d2bc5 x86: coding style fixes to arch/x86/lib/string_32.c
The patch kills 45 errors and a few warnings.

The file is now error/warning free:
total: 0 errors, 0 warnings, 237 lines checked
arch/x86/lib/string_32.c has no obvious style problems and is ready for submission.

no code changed:

arch/x86/lib/string_32.o:
   text    data     bss     dec     hex filename
    639       0       0     639     27f string_32.o.before
    639       0       0     639     27f string_32.o.after
md5:
2db1c48187cf5113bb595153ee1fc73d  string_32.o.before.asm
2db1c48187cf5113bb595153ee1fc73d  string_32.o.after.asm

Signed-off-by: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-17 17:40:48 +02:00
Andi Kleen 61d08a9ea3 i386: Remove strrchr assembler implementation
The constraints in the inline assembler implementation of i386
strrchr() were incorrect and break the build with recent gcc 4.3.
Since there are only very few callers of strrchr() and none of them
are performance relevant just remove the assembler implementation
and use the C fallback instead.

[ tglx: arch/x86 adaptation ]

Cc: rguenther@suse.de
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-17 20:16:23 +02:00
Thomas Gleixner 44f0257fc3 i386: move lib
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-11 11:16:33 +02:00