[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linaro-toolchain
Subject:    Improving libgmp [was: Re: Potential tools team work]
From:       michael.hope () linaro ! org (Michael Hope)
Date:       2011-08-18 1:19:38
Message-ID: CANLjY-kic2kC7i3M6q_xK--FGf2iCX4HPwkpF1a9qZMG3LAhwQ () mail ! gmail ! com
[Download RAW message or body]

On Thu, Aug 18, 2011 at 4:16 AM, Richard Earnshaw
<Richard.Earnshaw at arm.com> wrote:
> I was just browsing libgmp this afternoon and noticed that it really
> could do with an overhaul to support recent ARM chips.
>
> The ARM code seems to have been written for StrongARM; which is now
> almost obsolete (for example, it loads from a cache line it is about to
> write to in order to pre-allocate the line in the cache).
>
> It doesn't support v4T interworking.
>
> It doesn't make any use of v5 or later instructions.
>
> There is some Thumb(1) code, but again it has no support for
> interworking, is pretty poor and limited in scope.
>
> I'm not sure overall how useful this is to gcc performance; the library
> is needed to build GCC, but I think it's mostly there to support libmpfr.
>
> Nevertheless, there are other apps out there that make use of this
> stuff, including some crypto code, IIRC.

I looked at using gmp as a benchmark some time ago.  The assembly
version is twice as fast as the C version already, which is nice.  I
assume NEON would be a big improvement as well.

I had a quick poke through the dependencies in Ubuntu and came up with
the following popular packages that use libgmp or libmpfr:
 * guile
 * python-crypto
 * gch (Haskel)
 * maxima
 * darcs

Nothing earth shattering but probably worthwhile.  I've registered:
 https://blueprints.launchpad.net/linaro-toolchain-misc/+spec/improve-libgmp

so that we don't lose it.

-- Michael


[prev in list] [next in list] [prev in thread] [next in thread]