Files
mercury/compiler/inst_util.m
Zoltan Somogyi 625ec287f1 Carve five new modules out of prog_type.m.
compiler/prog_type_construct.m:
    New module for constructing types.

compiler/prog_type_repn.m:
    New module for testing things related to type representation.

compiler/prog_type_scan.m:
    New module for gather type vars in types.

compiler/prog_type_test.m:
    New module containing simple tests on types.

compiler/prog_type_unify.m:
    New module for testing whether two types unify, or whether
    one type subsumes another.

compiler/prog_type.m:
    Delete the code moved to the new modules.

compiler/parse_tree.m:
    Include the new modules.

compiler/notes/compiler_design.html:
    Document the new modules.

compiler/*.m:
    Conform to the changes above, by adjusting imports as needed,
    and by deleting any explicit module qualifications that
    this diff makes obsolete.
2023-10-06 08:42:43 +11:00

406 lines
16 KiB
Mathematica

%---------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%---------------------------------------------------------------------------%
% Copyright (C) 1997-2012 The University of Melbourne.
% Copyright (C) 2015 The Mercury team.
% This file may only be copied under the terms of the GNU General
% Public License - see the file COPYING in the Mercury distribution.
%---------------------------------------------------------------------------%
%
% File: inst_util.m.
% Author: fjh.
%
% This module defines some utility routines for manipulating insts.
%
%---------------------------------------------------------------------------%
:- module check_hlds.inst_util.
:- interface.
:- import_module hlds.
:- import_module hlds.hlds_module.
:- import_module parse_tree.
:- import_module parse_tree.prog_data.
:- import_module list.
%---------------------------------------------------------------------------%
% Given an inst, return a new inst which is the same as the original inst
% but with all occurrences of `unique' replaced with `mostly_unique'.
%
:- pred make_mostly_uniq_inst(mer_inst::in, mer_inst::out,
module_info::in, module_info::out) is det.
% Given a list of insts, return a new list of insts which is the same
% as the original list of insts, but with all occurrences of `unique'
% replaced with `shared'. It is an error if any part of the inst list
% is free.
%
:- pred make_shared_inst_list(list(mer_inst)::in, list(mer_inst)::out,
module_info::in, module_info::out) is det.
% Make an inst shared; replace all occurrences of `unique' or
% `mostly_unique' in the inst with `shared'.
%
:- pred make_shared_inst(mer_inst::in, mer_inst::out,
module_info::in, module_info::out) is det.
:- pred make_shared_bound_inst_list(list(bound_inst)::in,
list(bound_inst)::out, module_info::in, module_info::out) is det.
%---------------------------------------------------------------------------%
% Return the default mode for a function of the given arity.
%
:- func pred_inst_info_default_func_mode(arity) = pred_inst_info.
%---------------------------------------------------------------------------%
%
% These utility predicates on types are in this module because they are needed
% *only* by code that manipulates insts.
%
% If possible, get the argument types for the cons_id. We need to pass in
% the arity rather than using the arity from the cons_id because the arity
% in the cons_id will not include any extra type_info arguments for
% existentially quantified types.
%
% This utility predicate on types is in this module because it is needed
% *only* by code that manipulates insts.
%
% XXX This predicate returns the types of the arguments, but
% loses any ho_inst_info for the arguments.
%
:- pred get_cons_id_arg_types(module_info::in, mer_type::in,
cons_id::in, arity::in, list(mer_type)::out) is det.
% XXX This predicate returns the types of the arguments, but
% loses any ho_inst_info for the arguments.
%
:- pred get_higher_order_arg_types(mer_type::in, arity::in,
list(mer_type)::out) is det.
% Return a type that represents the *absence* of type information.
% This type is a type variable. Since the predicates and functions
% working on insts and modes use type information *only* to look up
% the constructors of a type, this conveys exactly the right info.
%
% Note that we always return the *same* type variable. Besides matching
% the semantics expected of functions, it also means our callers will not
% construct non-canonical inst_match_inputs structures. The fact that
% we return the same type variable as the "types" of e.g. different
% existentially typed arguments of a data constructor is not a problem,
% even though those arguments may contain values of different types at
% runtime, because the predicates working insts and modes never compare
% the types associated with those insts and modes for equality.
%
:- func no_type_available = mer_type.
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module check_hlds.inst_lookup.
:- import_module check_hlds.inst_match.
:- import_module check_hlds.inst_test.
:- import_module check_hlds.type_util.
:- import_module hlds.hlds_inst_mode.
:- import_module mdbcomp.
:- import_module mdbcomp.prim_data.
:- import_module parse_tree.prog_mode.
:- import_module parse_tree.prog_type_test.
:- import_module int.
:- import_module maybe.
:- import_module require.
:- import_module varset.
%---------------------------------------------------------------------------%
make_mostly_uniq_inst(Inst0, Inst, !ModuleInfo) :-
(
( Inst0 = not_reached
; Inst0 = free
),
Inst = Inst0
;
Inst0 = any(Uniq0, HOInstInfo),
make_mostly_uniq(Uniq0, Uniq),
Inst = any(Uniq, HOInstInfo)
;
Inst0 = bound(Uniq0, _InstResults0, BoundInsts0),
% XXX could improve efficiency by avoiding recursion here
make_mostly_uniq(Uniq0, Uniq),
make_mostly_uniq_bound_inst_list(BoundInsts0, BoundInsts, !ModuleInfo),
% XXX A better approximation of InstResults is probably possible.
Inst = bound(Uniq, inst_test_no_results, BoundInsts)
;
Inst0 = ground(Uniq0, PredInst),
make_mostly_uniq(Uniq0, Uniq),
Inst = ground(Uniq, PredInst)
;
Inst0 = inst_var(_),
unexpected($pred, "free inst var")
;
Inst0 = constrained_inst_vars(InstVars, SubInst0),
make_mostly_uniq_inst(SubInst0, SubInst, !ModuleInfo),
( if inst_matches_final(!.ModuleInfo, SubInst, SubInst0) then
Inst = constrained_inst_vars(InstVars, SubInst)
else
Inst = SubInst
)
;
Inst0 = defined_inst(InstName),
% Check whether the inst name is already in the mostly_uniq_inst table.
module_info_get_inst_table(!.ModuleInfo, InstTable0),
inst_table_get_mostly_uniq_insts(InstTable0, MostlyUniqInstTable0),
search_insert_unknown_mostly_uniq_inst(InstName, MaybeOldMaybeInst,
MostlyUniqInstTable0, MostlyUniqInstTable1),
(
MaybeOldMaybeInst = yes(OldMaybeInst),
(
OldMaybeInst = inst_known(MostlyUniqInst)
;
OldMaybeInst = inst_unknown,
MostlyUniqInst = defined_inst(InstName)
)
;
MaybeOldMaybeInst = no,
% We have inserted InstName into the table with value
% `inst_unknown'.
inst_table_set_mostly_uniq_insts(MostlyUniqInstTable1,
InstTable0, InstTable1),
module_info_set_inst_table(InstTable1, !ModuleInfo),
% Expand the inst name, and invoke ourself recursively on its
% expansion.
inst_lookup(!.ModuleInfo, InstName, SubInst0),
inst_expand(!.ModuleInfo, SubInst0, SubInst1),
make_mostly_uniq_inst(SubInst1, MostlyUniqInst, !ModuleInfo),
% Now that we have determined the resulting Inst, store the
% appropriate value `known(MostlyUniqInst)' in the
% mostly_uniq_inst table.
module_info_get_inst_table(!.ModuleInfo, InstTable2),
inst_table_get_mostly_uniq_insts(InstTable2, MostlyUniqInstTable2),
det_update_mostly_uniq_inst(InstName, inst_known(MostlyUniqInst),
MostlyUniqInstTable2, MostlyUniqInstTable),
inst_table_set_mostly_uniq_insts(MostlyUniqInstTable,
InstTable2, InstTable),
module_info_set_inst_table(InstTable, !ModuleInfo)
),
% Avoid expanding recursive insts.
( if
inst_contains_inst_name(!.ModuleInfo, InstName, MostlyUniqInst)
then
Inst = defined_inst(InstName)
else
Inst = MostlyUniqInst
)
).
:- pred make_mostly_uniq(uniqueness::in, uniqueness::out) is det.
make_mostly_uniq(unique, mostly_unique).
make_mostly_uniq(mostly_unique, mostly_unique).
make_mostly_uniq(shared, shared).
make_mostly_uniq(mostly_clobbered, mostly_clobbered).
make_mostly_uniq(clobbered, clobbered).
:- pred make_mostly_uniq_bound_inst_list(list(bound_inst)::in,
list(bound_inst)::out, module_info::in, module_info::out) is det.
make_mostly_uniq_bound_inst_list([], [], !ModuleInfo).
make_mostly_uniq_bound_inst_list([Bound0 | Bounds0], [Bound | Bounds],
!ModuleInfo) :-
Bound0 = bound_functor(ConsId, ArgInsts0),
make_mostly_uniq_inst_list(ArgInsts0, ArgInsts, !ModuleInfo),
Bound = bound_functor(ConsId, ArgInsts),
make_mostly_uniq_bound_inst_list(Bounds0, Bounds, !ModuleInfo).
:- pred make_mostly_uniq_inst_list(list(mer_inst)::in, list(mer_inst)::out,
module_info::in, module_info::out) is det.
make_mostly_uniq_inst_list([], [], !ModuleInfo).
make_mostly_uniq_inst_list([Inst0 | Insts0], [Inst | Insts], !ModuleInfo) :-
make_mostly_uniq_inst(Inst0, Inst, !ModuleInfo),
make_mostly_uniq_inst_list(Insts0, Insts, !ModuleInfo).
%---------------------------------------------------------------------------%
make_shared_inst_list([], [], !ModuleInfo).
make_shared_inst_list([Inst0 | Insts0], [Inst | Insts], !ModuleInfo) :-
make_shared_inst(Inst0, Inst, !ModuleInfo),
make_shared_inst_list(Insts0, Insts, !ModuleInfo).
make_shared_inst(Inst0, Inst, !ModuleInfo) :-
(
Inst0 = not_reached,
Inst = Inst0
;
Inst0 = free,
% The caller should ensure that this never happens.
unexpected($pred, "cannot make shared version of `free'")
;
Inst0 = any(Uniq0, HOInstInfo),
make_shared(Uniq0, Uniq),
Inst = any(Uniq, HOInstInfo)
;
Inst0 = bound(Uniq0, InstResults0, BoundInsts0),
% XXX This code has a performance problem.
%
% The problem is that e.g. in a list of length N, you will have
% N variables for the skeletons whose insts contain an average of
% N/2 occurences of `bound' each, so the complexity of running
% make_shared_inst on all their insts is quadratic in N.
%
% One potential way to fix this would be to introduce a new function
% symbol for insts, make_shared(mer_inst), which would have the meaning
% of requiring any compiler component that finds it to run
% make_shared_inst on its argument before using it. That would require
% parameterizing make_shared_inst to say whether it is being used
% in such a manner.
%
% Another similar fix would be to add an extra argument to bound/2
% to say whether the insts in its last argument should implicitly be
% made shared.
%
% If Uniq0 = shared, then all the other cells below it should also be
% shared as well, which means we should be able to avoid the call to
% make_shared_bound_inst_list below. However, for the kinds of goals
% for which the call is a bottleneck, the goals resulting from the
% construction of large ground terms, Uniq0 will in fact be `unique'.
make_shared(Uniq0, Uniq),
make_shared_bound_inst_list(BoundInsts0, BoundInsts, !ModuleInfo),
Inst = bound(Uniq, InstResults0, BoundInsts)
;
Inst0 = ground(Uniq0, PredInst),
make_shared(Uniq0, Uniq),
Inst = ground(Uniq, PredInst)
;
Inst0 = inst_var(_),
unexpected($pred, "free inst var")
;
Inst0 = constrained_inst_vars(InstVars, SubInst0),
make_shared_inst(SubInst0, SubInst1, !ModuleInfo),
( if inst_matches_final(!.ModuleInfo, SubInst1, SubInst0) then
Inst = constrained_inst_vars(InstVars, SubInst1)
else
Inst = SubInst1
)
;
Inst0 = defined_inst(InstName),
% Check whether the inst name is already in the shared_inst table.
module_info_get_inst_table(!.ModuleInfo, InstTable0),
inst_table_get_shared_insts(InstTable0, SharedInstTable0),
search_insert_unknown_shared_inst(InstName, MaybeOldMaybeInst,
SharedInstTable0, SharedInstTable1),
(
MaybeOldMaybeInst = yes(OldMaybeInst),
(
OldMaybeInst = inst_known(SharedInst)
;
OldMaybeInst = inst_unknown,
SharedInst = Inst0
)
;
MaybeOldMaybeInst = no,
% We have inserted SharedInstKey into the table with value
% `inst_unknown'.
inst_table_set_shared_insts(SharedInstTable1,
InstTable0, InstTable1),
module_info_set_inst_table(InstTable1, !ModuleInfo),
% Expand the inst name, and invoke ourself recursively on its
% expansion.
inst_lookup(!.ModuleInfo, InstName, SubInst0),
inst_expand(!.ModuleInfo, SubInst0, SubInst1),
make_shared_inst(SubInst1, SharedInst, !ModuleInfo),
% Now that we have determined the resulting Inst, store the
% appropriate value `known(SharedInst)' in the shared_inst table.
module_info_get_inst_table(!.ModuleInfo, InstTable2),
inst_table_get_shared_insts(InstTable2, SharedInstTable2),
det_update_shared_inst(InstName, inst_known(SharedInst),
SharedInstTable2, SharedInstTable),
inst_table_set_shared_insts(SharedInstTable,
InstTable2, InstTable),
module_info_set_inst_table(InstTable, !ModuleInfo)
),
% Avoid expanding recursive insts.
( if inst_contains_inst_name(!.ModuleInfo, InstName, SharedInst) then
Inst = defined_inst(InstName)
else
Inst = SharedInst
)
).
:- pred make_shared(uniqueness::in, uniqueness::out) is det.
make_shared(unique, shared).
make_shared(mostly_unique, shared).
make_shared(shared, shared).
make_shared(mostly_clobbered, mostly_clobbered).
make_shared(clobbered, clobbered).
make_shared_bound_inst_list([], [], !ModuleInfo).
make_shared_bound_inst_list([Bound0 | Bounds0], [Bound | Bounds],
!ModuleInfo) :-
Bound0 = bound_functor(ConsId, ArgInsts0),
make_shared_inst_list(ArgInsts0, ArgInsts, !ModuleInfo),
Bound = bound_functor(ConsId, ArgInsts),
make_shared_bound_inst_list(Bounds0, Bounds, !ModuleInfo).
%---------------------------------------------------------------------------%
pred_inst_info_default_func_mode(Arity) = PredInstInfo :-
in_mode(InMode),
out_mode(OutMode),
ArgModes = list.duplicate(Arity - 1, InMode) ++ [OutMode],
PredInstInfo = pred_inst_info(pf_function, ArgModes, arg_reg_types_unset,
detism_det).
%---------------------------------------------------------------------------%
get_cons_id_arg_types(ModuleInfo, Type, ConsId, Arity, Types) :-
( if
( ConsId = cons(_SymName, _, _)
; ConsId = tuple_cons(_)
)
then
( if
% XXX get_cons_id_non_existential_arg_types will fail
% for ConsIds with existentially typed arguments.
get_cons_id_non_existential_arg_types(ModuleInfo, Type,
ConsId, ArgTypes),
list.length(ArgTypes, Arity)
then
Types = ArgTypes
else
list.duplicate(Arity, no_type_available, Types)
)
else
Types = []
).
get_higher_order_arg_types(Type, Arity, Types) :-
( if type_is_higher_order_details(Type, _, _, _, ArgTypes) then
Types = ArgTypes
else
list.duplicate(Arity, no_type_available, Types)
).
%---------------------------------------------------------------------------%
no_type_available = Type :-
varset.init(VarSet0),
new_var(Var, VarSet0, _VarSet),
Type = type_variable(Var, kind_star).
%---------------------------------------------------------------------------%
:- end_module check_hlds.inst_util.
%---------------------------------------------------------------------------%