[m-rev.] for review: dead_pred_elim optimization

[Peter Ross]

On Thu, Mar 06, 2003 at 08:39:58PM +1100, Simon Taylor wrote:
> On 06-Mar-2003, Peter Ross <pro at missioncriticalit.com> wrote:
> > On Thu, Mar 06, 2003 at 04:17:37PM +1100, Simon Taylor wrote:
> > > On 05-Mar-2003, Peter Ross <pro at missioncriticalit.com> wrote:
> > > > Estimated hours taken: 4
> > > > Branches: main
> > > > 
> > > > Fix a performance bug where dead_pred_elim was taking a significant
> > > > amount of time to delete entries from the predicate_table.  With this
> > > > change dead_pred_elim goes from 12 minutes to 55 seconds CPU time in
> > > > the IL grade when compiling accumulator.m with
> > > > --intermodule-optimization turned on.
> 
> Is that 55 seconds for the entire compilation or just for
> dead_pred_elim?
> 
Just for the dead_pred_elim.

> > > > Index: compiler/hlds_module.m
> > > > ===================================================================
> > > > @@ -1756,22 +1765,45 @@
> > > >  
> > > >  %-----------------------------------------------------------------------------%
> > > >  
> > > > +predicate_table_restrict(OrigPredicateTable, PredIds, PredicateTable) :-
> > > > +	predicate_table_reset(OrigPredicateTable, PredicateTable0),
> > > > +	predicate_table_get_preds(OrigPredicateTable, Preds),
> > > > +	PredicateTable = list__foldl(
> > > > +			(func(PredId, Table0) = Table :-
> > > > +				PredInfo = map__lookup(Preds, PredId),
> > > > +				predicate_table_insert_2(Table0,
> > > > +						yes(PredId), PredInfo,
> > > > +						must_be_qualified,
> > > > +						no, _, Table)
> > > > +				
> > > > +			), PredIds, PredicateTable0).
> > > 
> > > The `must_be_qualified' here looks wrong.
> > > 
> > On second thoughts, I think you are right, I have changed it to
> > may_be_unqualified.
> 
> That's wrong too. You need to use the same value that was passed
> when the predicate was originally added to the predicate table.
> 

How about this?

predicate_table_restrict(OrigPredicateTable, PredIds, PredicateTable) :-
        OrigPredicateTable = predicate_table(Preds, NextPredId, _,
                        PredNameIndex, _, _, FuncNameIndex, _, _),
        PredicateTable0 = predicate_table(map__init, NextPredId, [], map__init,
                        map__init, map__init, map__init, map__init, map__init),
        PredicateTable = list__foldl(
                        (func(PredId, Table0) = Table :-
                                PredInfo = map__lookup(Preds, PredId),

                                pred_info_get_is_pred_or_func(PredInfo,
                                                IsPredOrFunc),
                                ( IsPredOrFunc = predicate,
                                        NameIndex = PredNameIndex
                                ; IsPredOrFunc = function,
                                        NameIndex = FuncNameIndex
                                ),

                                pred_info_name(PredInfo, Name),
                                (
                                        multi_map__nondet_search(NameIndex,
                                                        Name, PredId)
                                ->
                                        NeedQual = may_be_unqualified
                                ;
                                        NeedQual = must_be_qualified
                                ),

                                predicate_table_insert_2(Table0,
                                                yes(PredId), PredInfo,
                                                NeedQual, no, _, Table)

                        ), PredIds, PredicateTable0).
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