Re: [Mingw-users] GMP windows64 porting effort

[JonY <jo...@us...>]

On 6/30/2011 05:20, Torbjorn Granlund wrote:
> Hello,
> 
> I believe GMP (The GNU multiple precision arithmetic library) in its
> latest incarnation (release series 5.0) support 64-bit MinGW, but only
> rudimentarly.
> 

mingw-w64 is a separate project than mingw.org, mailing list at
min...@li.... Adding to CC.

> We plan to improve the support.  I nor any other of the GMP developers
> are Windows users, so please forgive some naivety.
> 
> Currently (i think) GMP configures and builds under MinGW-64, but GMP's
> performance leaves a lot to be desired, mainly since the GMP x86_64
> assembly does not work with Windows64's calling conventions.  (GMP's
> performance is very dependent on assembly code, unfortunately.)
> 
> We'd like to improve things in a two steps:
> 
> (1) Make the existing assembly code work by adding a rather simple layer
>     of abstraction to it.  We will still require a bash-type shell and
>     other unix-like commands, like e.g., m4 and make.
> 
> (2) Perhaps make things work, at least to some degree, with a more
>     Windowsy environment.
> 
> Questions:
> 
> Do people here agree that GMP works today (w/o assembly)?  Can indeed
> MinGW-64 run configure and 'make'?  Would I need to install external
> software, e.g., (parts of) Cygwin to make it work?
> 
> For step (1) above, will one have m4 from MinGW, or will that require
> external software (e.g., Cygwin)?  Do you see any other potential
> problems?
> 

Yes, you'll need a Unix support system either way. Neither mingw nor
mingw-w64 comes with m4, they come either from Cygwin or MSYS.

> I will worry about (2) at a later point.  The idea here is to not depend
> on Unixisms, whatever that means.  Gcc from MinGW will certainly still
> be useful (I suppose gcc can be run from within such systems as "Visual
> Studio"?)
> 

Please, no. Although I find GMP's use of --host to select asm features
appalling, I'd still rather use the autotools route. Besides visual
studio doesn't run on Linux out of the box.

Why would you be concerned about using Unix tools?

> (I am not at this list, please retain any CC to me.)
> 
> PS. Which is the recommened way to get started with mingw?  I find
> sources, but I really don't want to mess with setting up a cross
> compiltion environment at this early stage.  Should I install by means
> of Cygwin's installer?
> 

Yes, that's an easy route to go, GMP's build system already supports
rudimentary cross compile with --host, but I suspect you'll want to
"fix" it up so it doesn't try to jump to conclusions on $host.