Re: Alias sets

[Richard Henderson <rth at cygnus dot com>]

On Sat, Jun 03, 2000 at 10:47:26PM -0700, Mark Mitchell wrote:
>   RTH, I think we should back out this patch:
> 
>         2000-06-02  Richard Henderson  <rth@cygnus.com>
> 
> 	* alias.c (lang_get_alias_set): Remove.
> 	(get_alias_set): Call it directly, not indirectly.
> 	* c-common.c (lang_get_alias_set): Rename from c_get_alias_set.
> 	* c-common.h (c_get_alias_set): Don't declare.
> 	* c-decl.c (init_decl_processing): Don't set lang_get_alias_set.
> 	* expr.h (lang_get_alias_set): Declare as function, not pointer.
> 
> and the accompanying front-end patches.  I don't think language
> implementors should be saddled with alias sets at all if they don't
> want to deal.  It should be possible to right a correct front-end
> without providing this function; you just won't get as good
> optimization.  Do you agree?

Yes and no.  Yes, because a language shouldn't have to care
about alias sets.  No, because you have to make sure to get
lang_get_alias_set initialized early enough, and exactly how
early is not particularly obvious. 

It can be determined, of course, by trial and error -- which 
is in fact what happened here, in that it was wrong in the
initial checkin and I fixed it.  If we just go ahead and make
this a function, then we have no such problems.

I don't think it's that unreasonable to ask for a function
that just returns zero.  We already have a half-dozen other
functions that absolutely must exist, even if empty...

I do not, however, have strong feelings on the subject.


r~