On Fri, May 11, 2012 at 02:12:32PM +0200, Michael Matz wrote:
> On Fri, 11 May 2012, Basile Starynkevitch wrote:
>
> > However, the type gimple_seq still appears in a lot of source files
> > (mostly gcc/gimple*.c & gcc/tree*.c)
> >
> > Is this intended, or is this a temporary situation, and
> > further patches would remove all occurrences of gimple_seq everywhere?
>
> I'm personally undecided. Retaining gimple_seq would make it possible to
> change the implementation of sequences to something else relatively
> easily.
Then perhaps we should better have something like
/* a single GIMPLE statement.
Take care to use the gimple type when you are thinking of a single
statement
only, e.g. to retrieve its operands. */
typedef union gimple_statement_d *gimple;
/* a sequence of GIMPLE statements.
Use the gimple_seq type when thinking of a sequence of statements.
The gimple_seq might have a different representation some day (and used to
have one).
*/
typedef union gimple_statement_d *gimple_seq;
I believe the above is more understandable than a "typedef gimple gimple_seq;"
which brings some assymetry in the code.
If coding in C++, we could have
typedef class Gimple *gimple;
typedef class GimpleSeq *gimple_qeq;
And if we coded in C++, we would dare having
class Gimple_statement_data {
//....
};
class Gimple : public Gimple_statement_data {
//....
}
class GimpleSeq : public Gimple_statement_data {
//....
};
I really think that it is important to decide *now*
if gimple and gimple_seq are conceptually different
(and to document and comment that) or the same.
As you suggest, if we don't make a clear statement in a comment
and in documentation, things will surely degrade with time.
Cheers.
--
Basile STARYNKEVITCH http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
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*** opinions {are only mines, sont seulement les miennes} ***
