How does the register allocator supports modulo scheduled code?

[Jan Hubicka]

> Jan Hubicka writes:
>  > > 
>  > >    We have done the modulo scheduling for the loops and added that to the 
>  > > gcc instruction scheduler. We have replaced the loop block with our 
>  > > scheduled code and it is working fine. But now when this is passed to the 
>  > > gcc register allocator, we are getting errors in reload pass. Will the gcc 
>  > > register allocator can not handle this modulo scheduled code?
>  > 
>  > What kind of errors do you get exactly?  In case the insturctions you
>  > produced match the constraints it should work just OK.  In case they
>  > don't reload won't be able to fix up the hard registers.
> 
> Surely this can't work because reload will mess up the carefully
> arranged schedule.
In case you do the register allocation job, reload will do nothing, so
this can work.

Honza
> 
> Andrew.