Re: [Patch, IRA] Fix a function accessing beyond end-of-array

[Hari Sandanagobalane <hariharans at picochip dot com>]

On 11/05/11 19:32, Vladimir Makarov wrote:
> On 05/11/2011 10:07 AM, Hari Sandanagobalane wrote:
> > Hello,
> > I discussed this problem with Vlad in
> > http://gcc.gnu.org/ml/gcc/2011-05/msg00131.html. I propose the
> > following patch to fix it. Okay to commit?
> >
> > Revised the ChangeLog.
> >
> > Thanks
> > Hari
> >
> > ChangeLog:
> >          * ira.c (clarify_prohibited_class_mode_regs): Prevent the
> > function from accessing beyond the end of REGNO_REG_CLASS array by
> > stopping the loop early.
> >
> > Patch:
> > Index: gcc/ira.c
> > ===================================================================
> > --- gcc/ira.c   (revision 173654)
> > +++ gcc/ira.c   (working copy)
> > @@ -1422,6 +1422,12 @@
> >             if (TEST_HARD_REG_BIT
> > (ira_prohibited_class_mode_regs[cl][j], hard_regno))
> >               continue;
> >             nregs = hard_regno_nregs[hard_regno][j];
> > +          if (hard_regno + nregs>= FIRST_PSEUDO_REGISTER)
>
> I think it should be '>' not'>='

Vlad,

The REGNO_REG_CLASS is generally an array of size FIRST_PSEUDO_REGISTER. 
So, the indexes go from 0 to FIRST_PSEUDO_REGISTER-1. I think the ">=" 
condition is fine in that case. Do you agree?

Cheers
Hari

> With this change, the patch is ok.  Thanks for the patch.
>
> > +            {
> > +              SET_HARD_REG_BIT (ira_prohibited_class_mode_regs[cl][j],
> > +                                hard_regno);
> > +               continue;
> > +            }
> >             pclass = ira_pressure_class_translate[REGNO_REG_CLASS
> > (hard_regno)];
> >             for (nregs-- ;nregs>= 0; nregs--)
> >               if (((enum reg_class) pclass