Reload bug

[Jan Hubicka]

> > The code is wrong for post-SUBREG_BYTE patch as it checks that the
> > partial regs have exactly size of one word, but we do allow subregs on
> > registers of different sizes.  We need to verify that offset can
> > represent the register exactly.
> 
> Is it really wrong or is it incomplete now, in the post-SUBREG_BYTE era?
> 
> > Looking as subreg_regno_offset, I think we need to practically check
> > that division in:
> >   return (y_offset / (mode_multiple / nregs_multiple)) * nregs_ymode;
> > Does not round.  When it rounds we are having registers too wide and we
> > must reload.
> > All the other divisions should be safe from SUBREG definition that is
> > already verified by my simplify_subreg code.
> > We also should add a trap to subreg_regno_offset in the mainline...
> > Seems to make sense?
> 
> Do you mean that we can generate
> 
> 	(subreg:HI (reg/v:SI 67) 2)
> 
> and we currently have no means to fix it during the reload pass?

Forgot to mention, I have patch in testing, will send it as soon as I
will be able to access the net (it is down for some reason now)

Honza
> 
> -- 
> Eric Botcazou