Re: [PATCH] Teach SCCVN/FRE expression insertion, optimize type-punning through unions (final!)

[Paolo Bonzini <bonzini at gnu dot org>]

> > > + 	*state_in = fs.reg;
> > > + 	*state_in = fs.offset;
> > Better to write to two different variables, maybe?
> >
> > > +     union loc fs;
> > > +     for (;;)
> > > +     {
> > > + 	*state_in = fs.offset;
> > > + 	*state_in = fs.reg;
> > Likewise, and also make them volatile?
> >
> > > + 	    case 0:
> > > + 		*state_in = fs.reg;
> > > + 	    case 1:
> > > + 		*state_in = fs.offset;
> > Write to two variables here too?
>
> Both stores need to be connected via VOPs - all the above testcases
> are for situations we would ICE if the dominance / avail checks were
> not done (and we would be happen to visit the loads in the wrong order).

My concern is, what if DSE removes the first store?  If possible, I 
still think you should make the variable volatile.

Paolo