[m-dev.] for review: type specialization [1]

[Simon Taylor]

Hi,

> >  	list__foldl(dead_pred_elim_initialize, PredIds, 
> >  		DeadInfo0, DeadInfo1),
> >  	dead_pred_elim_analyze(DeadInfo1, DeadInfo),
> > -	DeadInfo = dead_pred_info(ModuleInfo1, _, _, NeededPreds, _),
> > +	DeadInfo = dead_pred_info(ModuleInfo1, _, _, NeededPreds2, _),
> > +
> > +	%
> > +	% If a predicate is not needed, predicates which were added in
> > +	% make_hlds.m to force type specialization are also not needed.
> > +	% Here we add in those which are needed.
> > +	%
> 
> Why are you doing that _after_ dead_pred_elim_analyze?

There are no calls to the specialized versions of predicates before
higher_order.m is run, so dead_pred_elim_analyze thinks that they are
not needed. This section makes sure that specialized versions are not
removed before higher_order.m has a chance to introduce calls to them.

> > +:- pred compute_extra_typeinfos(higher_order_info::in, list(prog_var)::in,
> > +		list(prog_var)::out, list(type)::out) is det.
> 
> How about a comment explaining what this predicate is supposed to do?

"
        % If `--typeinfo-liveness' is set, specializing type `T' to `list(U)'
        % requires passing in the type-info for `U'. This predicate
        % works out which extra variables to pass in given the argument
        % list for the call.
"

Simon.