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>
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>
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>
