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Re: [PATCH] i386: Assembly Implementation cleanup
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 12 Aug 2015 09:38:15 -0300
- Subject: Re: [PATCH] i386: Assembly Implementation cleanup
- Authentication-results: sourceware.org; auth=none
- References: <5596AD3B dot 1060903 at linaro dot org> <CAMe9rOof5LzNfW_Yd2qgtX2=UMdP-E-ewdneJ9GjiCF9SPyNqQ at mail dot gmail dot com>
On 11-08-2015 21:22, H.J. Lu wrote:
> On Fri, Jul 3, 2015 at 8:41 AM, Adhemerval Zanella
> <firstname.lastname@example.org> wrote:
>> This patch removes i386 assembly implementation for epoll_wait, mmap,
>> mmap64, semtimeop now that i386 have 6 argument syscall support from
>> C code.
>> The mmap implementation used is the wordsize-32 generic linux one.
>> Tested in i386.
>> * sysdeps/unix/sysv/linux/i386/mmap.c: New file.
>> * sysdeps/unix/sysv/linux/i386/epoll_pwait.S: Remove file.
>> * sysdeps/unix/sysv/linux/i386/mmap.S: Likewise.
>> * sysdeps/unix/sysv/linux/i386/mmap64.S: Likewise.
>> * sysdeps/unix/sysv/linux/i386/semtimedop.S: Likewise.
> What is the motivation? 6 argument syscalls aren't really inlined.
> They put arguments on stack and call __libc_do_syscall. It is
> slower than assembly code.
Same for ARM: code maintainability on functions that are not really
performance-critical. This avoids issues like the x86 pthread_cond_*
assembly implementation (which are now aimed to be removed), that
required specific fixes just for x86.