Re: [BUILDROBOT] nios2: build breakage

[Sandra Loosemore <sandra at codesourcery dot com>]

On 11/15/2014 04:49 PM, Jan-Benedict Glaw wrote:
> Hi,
>
> On Sun, 2014-11-16 00:36:27 +0100, Jan Hubicka <hubicka@ucw.cz> wrote:
> > > Yep, it is because my code does not handle streaming of arrays
> > > into the target optimization nodes.  I will take a look on why
> > > that array is really needed. It seems like a overkill?
> >
> > I am looking into the nios2_register_custom_code and I do not quite
> > understand what it is good for?  If it tracks customs codes function
> > wide, then perhaps target part of cfun would be better place to home
> > it.  It it is unit wide, then saving/restoring does not seem to make
> > much sense.
> >
> > Can you, please, explain me why this needs to be stored into target
> > option structure?  If this is really needed, then we can always add
> > a support for streaming arrays, but I would preffer keeping that
> > structure small and simple ;)
>
> Port maintainers Cc'ed.

I can explain why this is needed, at least.

The Nios II architecture optionally allows "custom instructions" that 
are typically used to implement floating-point operations.  The nios2 
GCC backend knows to generate these instructions if the user tells it 
what opcodes implement these instructions.  This is typically done by 
command-line options, but can also be done on a per-function basis by 
means of target attributes or pragmas -- see 
gcc/testsuite/gcc.target/nios2/custom-fp-* for examples.  The 
command-line options, attribute, and pragma support was a requirement 
from Altera, so yes, this is really needed.

-Sandra