Re: forward references in equates

[Alan Modra <amodra at bigpond dot net dot au>]

On Mon, Sep 19, 2005 at 09:35:51AM +0200, Jan Beulich wrote:
> >>> Alan Modra <amodra@bigpond.net.au> 17.09.05 16:14:46 >>>
> >On Fri, Sep 16, 2005 at 01:58:19PM +0200, Jan Beulich wrote:
> >> 
> >>  .equiv two, 2*one
> >>  .equ one, 1
> >>  .equiv three, 3*one
> >> 
> >>  .data
> >> 
> >> 	.byte	one
> >> 	.byte	two
> >> 	.byte	three
> >
> >I'd be reasonably confortable if gas gave 1, 2, 3 for the above,
> 
> That'd be my expectation, too.
> 
> >>  .equ one, -1
> >> 	.byte	one
> >> 	.byte	two
> >> 	.byte	three
> >
> >but what should these be?  I'd be inclined to say -1, 2, 3.  Are you
> >proposing that the last three values be -1, -2, -3?  That would be
> >changing the meaning of .equiv, I think.
> 
> I'm not as determined about the third value, but the second value
> should certainly be -2 (as the definition of two is clearly using a
> forward reference).

I don't agree that it follows from the definition of "two" being a
forward reference to "one" that the evaluation of "two" *must* always be
"2*one".  .set and its variations define symbols, not functions or
macros, so there are other quite reasonable possibilities.  I'm not
saying that expecting -2 is unreasonable, in fact that might be the most
useful result.  What do other assemblers give for your testcase?

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre