Re: [PATCH]: RTL iterators

[Richard Henderson <rth at redhat dot com>]

On Fri, Aug 10, 2001 at 12:15:17AM -0400, Daniel Berlin wrote:
> I would argue this is not true.

You'd be wrong.

> for_each_rtx is from August, 1998.

So?  How much code is still hanging around from 1990?
More than you think, that's for sure.

> Since then, the only place it's been used is the SSA stuff.

Grep again.  It's used in quite a few places.

> > I can't see how "next" is by itself meaningful in any way.
> You've taken it out of context, of course.
> You missed there's a cookie...

Clearly you missed my point entirely.

> I.E.
> (set (reg:SI a) (reg:SI b))
> get_next_REG would first hand you (reg:SI a), then (reg:SI b), then NULL.

Yeah, so?  Did you skip over the "I want Sets" or "I want Uses"
part of my query?  I disbelieve "I want any reg whatsoever" is
used nearly as often.

> >of the time we need to know whether "X" is read, set, or clobbered.
> while ((rtx = get_next_SET (insn, cookie)) != NULL)
> {
>         if (SET_DEST (rtx) == X)
>            /* It's written */
>         else if (SET_SRC (rtx) == X)
>            /* It's read */     
> }
> (Best I can do, or anyone could do, without knowing what *type* of X
> you are looking for.)

Have to work harder than that.  See, at minimum, note_stores.

> Why?  Because it's easier, and there is nothing better about writing
> tons of small callbacks.

Oh I'd agree that it would be easier.  What I disagree with is
that the code that you've written is good enough.


r~