linux-kernel - Re: [PATCH 0/1] vsprintf: optimize decimal conversion (again)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <201203281320.07765.vda.linux@googlemail.com>
Date:	Wed, 28 Mar 2012 13:20:07 +0200
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	roma1390 <roma1390@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Douglas W Jones <jones@...uiowa.edu>,
	Michal Nazarewicz <mnazarewicz@...gle.com>
Subject: Re: [PATCH 0/1] vsprintf: optimize decimal conversion (again)

On Wednesday 28 March 2012 12:39, roma1390 wrote:
> On 2012.03.28 13:33, Denys Vlasenko wrote:
> > On Wednesday 28 March 2012 12:24, roma1390 wrote:
> >> On 2012.03.28 13:13, Denys Vlasenko wrote:
> >>> Second: run
> >>> arm-linux-gnueabi-gcc -O2 -Wall test_{org,new}.c -S
> >>> and email me resulting test_{org,new}.s files.
> >>
> >> test_{org,new}.s attached.
> >
> >
> > Bingo.
> >
> >          bl      __aeabi_uidivmod
> >
> > Not good. Your gcc did not optimize division by constant.
> >
> > Can you add  "noinline_for_stack":
> >
> > static noinline_for_stack<=== HERE
> > char *put_dec(char *buf, unsigned long long n)
> >
> > amd regenerate and resend the test_new.s?
> >
> 
> Hello,
> 
> Your requested asm are attached.

Asm looks good: there are only three long multiplies in the
put_dec + put_dec_full4, and no divisions at all.

Please speed-test this version.

-- 
vda
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/