Re: [parisc-linux] [gcc] should we teach gcc some new tricks?

["Joel Soete" <soete.joel@tiscali.be>]

> -- Original Message --
> Date: Wed, 22 Jun 2005 23:27:53 -0600
> From: Grant Grundler <grundler@parisc-linux.org>
> To: Joel Soete <soete.joel@tiscali.be>
> Cc: parisc-linux@lists.parisc-linux.org
> Subject: Re: [parisc-linux] [gcc] should we teach gcc some new tricks?
> 
> 
> On Wed, Jun 22, 2005 at 07:54:54PM +0000, Joel Soete wrote:
> > of fp registers?
> > or how may I try to define it as accurately as possible?
> > (I objdump a operating 2.6.12-rc.-pa. 64bit to grep some 'fr[12][0..9=
]'
> and 
> > all of them seems to be used?
> 
> Of course they will all be used - kernel has to save and restore
> process state when switching context.
Oops I missed it (my bad)

> You have to look at each
> use and determine why FP is being used. There shouldn't
> be that many different uses.
> 
Thanks for enlightenment,

I still have to make a lot of progress ;-)

> > Do I have to look elsewhere; tausq also spoke about: sic
> > [...]One proposal that has been talked about before is if we can
> > compile a version of the millicode lib that uses limited fpregs range=

> > and compile the kernel using this new option that Dave is talking abo=
ut,
> > then we will be able to get by using a (much) smaller subset of fp re=
gs
> > and we won't have to save/restore them in the kernel. )
> 
> That's correct - but we will still have to save/restore all FP regs
> on a general context switch - just a subset of those when
> entering/leaving the kernel (e.g. handling an external interrupt).
> 
Thanks,
    Joel


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