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b2012c0c0e
Estimated hours taken: 8 Branches: main compiler/*.m: Rename the types 'type', 'inst' and 'mode' to 'mer_type', 'mer_inst' and 'mer_mode'. This is to avoid the need to parenthesize these type names in some contexts, and to prepare for the possibility of a parser that considers those words to be reserved words. Rename some other uses of those names (e.g. as item types in recompilation.m). Delete some redundant synonyms (prog_type, mercury_type) for mer_type. Change some type names (e.g. mlds__type) and predicate names (e.g. deforest__goal) to make them unique even without module qualification. Rename the function symbols (e.g. pure, &) that need to be renamed to avoid the need to parenthesize them. Make their replacement names more expressive. Convert some more modules to four space indentation. Avoid excessively long lines, such as those resulting from the automatic substitution of 'mer_type' for 'type'.
733 lines
28 KiB
Mathematica
733 lines
28 KiB
Mathematica
%-----------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%-----------------------------------------------------------------------------%
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% Copyright (C) 1994-2005 The University of Melbourne.
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% This file may only be copied under the terms of the GNU General
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% Public License - see the file COPYING in the Mercury distribution.
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%-----------------------------------------------------------------------------%
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%
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% Switch detection - when a disjunction contains disjuncts that unify the
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% same input variable with different function symbols, replace (part of)
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% the disjunction with a switch.
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%
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% Main author: fjh.
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%
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%-----------------------------------------------------------------------------%
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:- module check_hlds__switch_detection.
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:- interface.
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:- import_module hlds__hlds_goal.
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:- import_module hlds__hlds_module.
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:- import_module hlds__hlds_pred.
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:- import_module parse_tree__prog_data.
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:- import_module bool.
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:- import_module io.
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:- import_module list.
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:- pred detect_switches(module_info::in, module_info::out,
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io::di, io::uo) is det.
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:- pred detect_switches_in_proc(proc_id::in, pred_id::in,
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module_info::in, module_info::out) is det.
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% find_bind_var(Var, ProcessUnify, Goal0, Goal, !Result, !Info,
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% FoundDeconstruct):
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%
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% Used by both switch_detection and cse_detection. Searches through
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% `Goal0' looking for the first deconstruction unification with `Var'
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% or an alias of `Var'. If a deconstruction unification of the
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% variable is found, `ProcessUnify' is called to handle it (which may
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% replace the unification with some other goals, which is why we return
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% Goal), and searching is stopped. If we don't find such a deconstruction,
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% `!Result' is unchanged.
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%
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:- pred find_bind_var(prog_var::in,
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process_unify(Result, Info)::in(process_unify),
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hlds_goal::in, hlds_goal::out, Result::in, Result::out,
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Info::in, Info::out, bool::out) is det.
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:- type process_unify(Result, Info) ==
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pred(prog_var, hlds_goal, list(hlds_goal), Result, Result, Info, Info).
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:- inst process_unify == (pred(in, in, out, in, out, in, out) is det).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- implementation.
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:- import_module check_hlds__det_util.
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:- import_module check_hlds__inst_match.
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:- import_module check_hlds__type_util.
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:- import_module hlds__goal_util.
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:- import_module hlds__hlds_data.
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:- import_module hlds__hlds_goal.
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:- import_module hlds__instmap.
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:- import_module hlds__passes_aux.
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:- import_module hlds__quantification.
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:- import_module parse_tree__error_util.
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:- import_module parse_tree__prog_data.
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:- import_module parse_tree__prog_mode.
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:- import_module assoc_list.
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:- import_module char.
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:- import_module int.
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:- import_module map.
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:- import_module require.
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:- import_module set.
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:- import_module std_util.
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:- import_module term.
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%-----------------------------------------------------------------------------%
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detect_switches(!ModuleInfo, !IO) :-
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% Traverse the module structure, calling `detect_switches_in_goal'
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% for each procedure body.
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module_info_predids(!.ModuleInfo, PredIds),
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detect_switches_in_preds(PredIds, !ModuleInfo, !IO).
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:- pred detect_switches_in_preds(list(pred_id)::in,
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module_info::in, module_info::out, io::di, io::uo) is det.
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detect_switches_in_preds([], !ModuleInfo, !IO).
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detect_switches_in_preds([PredId | PredIds], !ModuleInfo, !IO) :-
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module_info_preds(!.ModuleInfo, PredTable),
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map__lookup(PredTable, PredId, PredInfo),
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detect_switches_in_pred(PredId, PredInfo, !ModuleInfo, !IO),
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detect_switches_in_preds(PredIds, !ModuleInfo, !IO).
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:- pred detect_switches_in_pred(pred_id::in, pred_info::in,
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module_info::in, module_info::out, io::di, io::uo) is det.
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detect_switches_in_pred(PredId, PredInfo0, !ModuleInfo, !IO) :-
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ProcIds = pred_info_non_imported_procids(PredInfo0),
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(
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ProcIds = [_ | _],
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write_pred_progress_message("% Detecting switches in ", PredId,
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!.ModuleInfo, !IO)
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;
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ProcIds = []
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),
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detect_switches_in_procs(ProcIds, PredId, !ModuleInfo).
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:- pred detect_switches_in_procs(list(proc_id)::in, pred_id::in,
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module_info::in, module_info::out) is det.
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detect_switches_in_procs([], _PredId, !ModuleInfo).
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detect_switches_in_procs([ProcId | ProcIds], PredId, !ModuleInfo) :-
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detect_switches_in_proc(ProcId, PredId, !ModuleInfo),
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detect_switches_in_procs(ProcIds, PredId, !ModuleInfo).
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detect_switches_in_proc(ProcId, PredId, !ModuleInfo) :-
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module_info_preds(!.ModuleInfo, PredTable0),
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map__lookup(PredTable0, PredId, PredInfo0),
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pred_info_procedures(PredInfo0, ProcTable0),
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map__lookup(ProcTable0, ProcId, ProcInfo0),
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% To process each ProcInfo, we get the goal, initialize the instmap
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% based on the modes of the head vars, and pass these to
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% `detect_switches_in_goal'.
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proc_info_goal(ProcInfo0, Goal0),
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proc_info_vartypes(ProcInfo0, VarTypes),
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proc_info_get_initial_instmap(ProcInfo0, !.ModuleInfo, InstMap0),
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detect_switches_in_goal(!.ModuleInfo, VarTypes, InstMap0, Goal0, Goal,
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no, Requant),
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proc_info_set_goal(Goal, ProcInfo0, ProcInfo1),
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(
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Requant = yes,
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requantify_proc(ProcInfo1, ProcInfo)
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;
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Requant = no,
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ProcInfo = ProcInfo1
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),
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map__det_update(ProcTable0, ProcId, ProcInfo, ProcTable),
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pred_info_set_procedures(ProcTable, PredInfo0, PredInfo),
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map__det_update(PredTable0, PredId, PredInfo, PredTable),
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module_info_set_preds(PredTable, !ModuleInfo).
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%-----------------------------------------------------------------------------%
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% Given a goal, and the instmap on entry to that goal,
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% replace disjunctions with switches whereever possible.
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%
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:- pred detect_switches_in_goal(module_info::in, vartypes::in,
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instmap::in, hlds_goal::in, hlds_goal::out, bool::in, bool::out) is det.
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap0, !Goal, !Requant) :-
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detect_switches_in_goal_1(ModuleInfo, VarTypes, InstMap0, _InstMap,
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!Goal, !Requant).
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% This version is the same as the above except that it returns the
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% resulting instmap on exit from the goal, which is computed by applying
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% the instmap delta specified in the goal's goalinfo.
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%
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:- pred detect_switches_in_goal_1(module_info::in, vartypes::in,
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instmap::in, instmap::out, hlds_goal::in, hlds_goal::out,
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bool::in, bool::out) is det.
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detect_switches_in_goal_1(ModuleInfo, VarTypes, !InstMap,
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Goal0 - GoalInfo, Goal - GoalInfo, !Requant) :-
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detect_switches_in_goal_2(ModuleInfo, VarTypes, !.InstMap, GoalInfo,
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Goal0, Goal, !Requant),
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update_instmap(Goal0 - GoalInfo, !InstMap).
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% Here we process each of the different sorts of goals.
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%
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:- pred detect_switches_in_goal_2(module_info::in, vartypes::in, instmap::in,
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hlds_goal_info::in, hlds_goal_expr::in, hlds_goal_expr::out,
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bool::in, bool::out) is det.
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detect_switches_in_goal_2(ModuleInfo, VarTypes, InstMap0, GoalInfo,
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Goal0, Goal, !Requant) :-
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(
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Goal0 = disj(Goals0),
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(
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Goals0 = [],
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Goal = disj([])
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;
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Goals0 = [_ | _],
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goal_info_get_nonlocals(GoalInfo, NonLocals),
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set__to_sorted_list(NonLocals, NonLocalsList),
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detect_switches_in_disj(NonLocalsList, Goals0, GoalInfo, InstMap0,
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VarTypes, NonLocalsList, ModuleInfo, [], Goal, !Requant)
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)
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;
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Goal0 = conj(Goals0),
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detect_switches_in_conj(ModuleInfo, VarTypes, InstMap0, Goals0, Goals,
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!Requant),
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Goal = conj(Goals)
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;
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Goal0 = par_conj(Goals0),
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detect_switches_in_par_conj(ModuleInfo, VarTypes, InstMap0,
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Goals0, Goals, !Requant),
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Goal = par_conj(Goals)
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;
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Goal0 = not(SubGoal0),
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap0,
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SubGoal0, SubGoal, !Requant),
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Goal = not(SubGoal)
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;
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Goal0 = if_then_else(Vars, Cond0, Then0, Else0),
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detect_switches_in_goal_1(ModuleInfo, VarTypes, InstMap0, InstMap1,
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Cond0, Cond, !Requant),
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap1, Then0, Then,
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!Requant),
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap0, Else0, Else,
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!Requant),
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Goal = if_then_else(Vars, Cond, Then, Else)
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;
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Goal0 = switch(Var, CanFail, Cases0),
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detect_switches_in_cases(ModuleInfo, VarTypes, InstMap0,
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Cases0, Cases, !Requant),
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Goal = switch(Var, CanFail, Cases)
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;
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Goal0 = scope(Reason, SubGoal0),
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap0,
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SubGoal0, SubGoal, !Requant),
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Goal = scope(Reason, SubGoal)
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;
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Goal0 = unify(_, RHS0, _, _, _),
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( RHS0 = lambda_goal(_, _, _, _, _, Vars, Modes, _, LambdaGoal0) ->
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% we need to insert the initial insts for the lambda
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% variables in the instmap before processing the lambda goal
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instmap__pre_lambda_update(ModuleInfo, Vars, Modes,
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InstMap0, InstMap1),
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap1,
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LambdaGoal0, LambdaGoal, !Requant),
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RHS = RHS0 ^ rhs_lambda_goal := LambdaGoal,
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Goal = Goal0 ^ unify_rhs := RHS
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;
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Goal = Goal0
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)
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;
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Goal0 = generic_call(_, _, _, _),
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Goal = Goal0
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;
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Goal0 = call(_, _, _, _, _, _),
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Goal = Goal0
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;
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Goal0 = foreign_proc(_, _, _, _, _, _),
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Goal = Goal0
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;
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Goal0 = shorthand(_),
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% These should have been expanded out by now.
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unexpected(this_file, "detect_switches_in_goal_2: shorthand")
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).
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%-----------------------------------------------------------------------------%
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:- type cases == map(cons_id, list(hlds_goal)).
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:- type sorted_case_list == list(case).
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% the sorted_case_list should always be sorted on cons_id -
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% `delete_unreachable_cases' relies on this.
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:- type again ---> again(prog_var, list(hlds_goal), sorted_case_list).
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% This is the interesting bit - we've found a non-empty disjunction,
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% and we've got a list of the non-local variables of that disjunction.
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% Now for each non-local variable, we check whether there is a partition
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% of the disjuncts such that each group of disjunctions can only succeed
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% if the variable is bound to a different functor.
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%
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:- pred detect_switches_in_disj(list(prog_var)::in, list(hlds_goal)::in,
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hlds_goal_info::in, instmap::in, vartypes::in,
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list(prog_var)::in, module_info::in, list(again)::in,
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hlds_goal_expr::out, bool::in, bool::out) is det.
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detect_switches_in_disj([Var | Vars], Goals0, GoalInfo, InstMap,
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VarTypes, AllVars, ModuleInfo, Again0, Goal, !Requant) :-
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% Can we do at least a partial switch on this variable?
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(
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instmap__lookup_var(InstMap, Var, VarInst0),
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inst_is_bound(ModuleInfo, VarInst0),
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partition_disj(Goals0, Var, GoalInfo, Left, CasesList, !Requant)
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->
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% A switch needs to have at least two cases.
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%
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% But, if there is a complete one-case switch for a goal, we must leave
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% it as a disjunction rather than doing an incomplete switch on a
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% different variable, because otherwise we might get determinism
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% analysis wrong. (The complete one-case switch may be decomposable
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% into other complete sub-switches on the functor's arguments)
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(
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% Are there any disjuncts that are not part of the switch? No.
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Left = [],
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( CasesList = [_, _ | _] ->
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cases_to_switch(CasesList, Var, VarTypes, GoalInfo, InstMap,
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ModuleInfo, Goal, !Requant)
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;
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detect_sub_switches_in_disj(ModuleInfo, VarTypes, InstMap,
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Goals0, Goals, !Requant),
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Goal = disj(Goals)
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)
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;
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% Are there any disjuncts that are not part of the switch? Yes.
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Left = [_ | _],
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% Insert this switch into the list of incomplete switches
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% only if it has at least two cases.
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( CasesList = [_, _ | _] ->
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Again1 = [again(Var, Left, CasesList) | Again0]
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;
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Again1 = Again0
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),
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% Try to find a switch.
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detect_switches_in_disj(Vars, Goals0, GoalInfo, InstMap, VarTypes,
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AllVars, ModuleInfo, Again1, Goal, !Requant)
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)
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;
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detect_switches_in_disj(Vars, Goals0, GoalInfo, InstMap,
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VarTypes, AllVars, ModuleInfo, Again0, Goal, !Requant)
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).
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detect_switches_in_disj([], Goals0, GoalInfo, InstMap,
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VarTypes, AllVars, ModuleInfo, AgainList0, disj(Goals), !Requant) :-
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(
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AgainList0 = [],
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detect_sub_switches_in_disj(ModuleInfo, VarTypes, InstMap,
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Goals0, Goals, !Requant)
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;
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AgainList0 = [Again | AgainList1],
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select_best_switch(AgainList1, Again, BestAgain),
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BestAgain = again(Var, Left0, CasesList),
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cases_to_switch(CasesList, Var, VarTypes, GoalInfo, InstMap,
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ModuleInfo, SwitchGoal, !Requant),
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detect_switches_in_disj(AllVars, Left0, GoalInfo, InstMap,
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VarTypes, AllVars, ModuleInfo, [], Left, !Requant),
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goal_to_disj_list(Left - GoalInfo, LeftList),
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Goals = [SwitchGoal - GoalInfo | LeftList]
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).
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:- pred select_best_switch(list(again)::in, again::in, again::out) is det.
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select_best_switch([], BestAgain, BestAgain).
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select_best_switch([Again | AgainList], BestAgain0, BestAgain) :-
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(
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Again = again(_, _, CasesList),
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BestAgain0 = again(_, _, BestCasesList),
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list__length(CasesList, Length),
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list__length(BestCasesList, BestLength),
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Length < BestLength
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->
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BestAgain1 = BestAgain0
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;
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BestAgain1 = Again
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),
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select_best_switch(AgainList, BestAgain1, BestAgain).
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:- pred detect_sub_switches_in_disj(module_info::in, vartypes::in, instmap::in,
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list(hlds_goal)::in, list(hlds_goal)::out, bool::in, bool::out) is det.
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detect_sub_switches_in_disj(_ModuleInfo, _VarTypes, _InstMap, [], [],
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!Requant).
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detect_sub_switches_in_disj(ModuleInfo, VarTypes, InstMap,
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[Goal0 | Goals0], [Goal | Goals], !Requant) :-
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap, Goal0, Goal,
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!Requant),
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detect_sub_switches_in_disj(ModuleInfo, VarTypes, InstMap,
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Goals0, Goals, !Requant).
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:- pred detect_switches_in_cases(module_info::in, vartypes::in, instmap::in,
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list(case)::in, list(case)::out, bool::in, bool::out) is det.
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|
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detect_switches_in_cases(_, _, _, [], [], !Requant).
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detect_switches_in_cases(ModuleInfo, VarTypes, InstMap,
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[Case0 | Cases0], [Case | Cases], !Requant) :-
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Case0 = case(Functor, Goal0),
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap, Goal0, Goal,
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!Requant),
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Case = case(Functor, Goal),
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detect_switches_in_cases(ModuleInfo, VarTypes, InstMap, Cases0, Cases,
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!Requant).
|
|
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:- pred detect_switches_in_par_conj(module_info::in, vartypes::in, instmap::in,
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list(hlds_goal)::in, list(hlds_goal)::out, bool::in, bool::out) is det.
|
|
|
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detect_switches_in_par_conj(_, _, _, [], [], !Requant).
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|
detect_switches_in_par_conj(ModuleInfo, VarTypes, InstMap,
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[Goal0 | Goals0], [Goal | Goals], !Requant) :-
|
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detect_switches_in_goal(ModuleInfo, VarTypes, InstMap, Goal0, Goal,
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!Requant),
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detect_switches_in_par_conj(ModuleInfo, VarTypes, InstMap,
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Goals0, Goals, !Requant).
|
|
|
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:- pred detect_switches_in_conj(module_info::in, vartypes::in, instmap::in,
|
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list(hlds_goal)::in, list(hlds_goal)::out, bool::in, bool::out) is det.
|
|
|
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detect_switches_in_conj(_, _, _, [], [], !Requant).
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detect_switches_in_conj(ModuleInfo, VarTypes, InstMap0,
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[Goal0 | Goals0], [Goal | Goals], !Requant) :-
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detect_switches_in_goal_1(ModuleInfo, VarTypes, InstMap0, InstMap1,
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Goal0, Goal, !Requant),
|
|
detect_switches_in_conj(ModuleInfo, VarTypes, InstMap1, Goals0, Goals,
|
|
!Requant).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
% partition_disj(Goals, Var, GoalInfo, VarTypes, ModuleInfo, Left, Cases):
|
|
%
|
|
% Attempts to partition the disjunction `Goals' into a switch on `Var'.
|
|
% If at least partially successful, returns the resulting `Cases', with
|
|
% any disjunction goals not fitting into the switch in Left.
|
|
%
|
|
% Given the list of goals in a disjunction, and an input variable to switch
|
|
% on, we attempt to partition the goals into a switch. For each constructor
|
|
% id, we record the list of disjuncts which unify the variable with that
|
|
% constructor. We partition the goals by abstractly interpreting the
|
|
% unifications at the start of each disjunction, to build up a
|
|
% substitution.
|
|
%
|
|
:- pred partition_disj(list(hlds_goal)::in, prog_var::in, hlds_goal_info::in,
|
|
list(hlds_goal)::out, sorted_case_list::out, bool::in, bool::out)
|
|
is semidet.
|
|
|
|
partition_disj(Goals0, Var, GoalInfo, Left, CasesList, !Requant) :-
|
|
map__init(Cases0),
|
|
partition_disj_trial(Goals0, Var, [], Left1, Cases0, Cases1),
|
|
map__to_assoc_list(Cases1, CasesAssocList1),
|
|
CasesAssocList1 = [_ | _], % There must be at least one case.
|
|
(
|
|
Left1 = [],
|
|
Left = Left1,
|
|
fix_case_list(CasesAssocList1, GoalInfo, CasesList)
|
|
;
|
|
Left1 = [_ | _],
|
|
( expand_sub_disjs(Var, Left1, Cases1, Cases) ->
|
|
Left = [],
|
|
map__to_assoc_list(Cases, CasesAssocList),
|
|
CasesAssocList = [_ | _], % There must be at least one case.
|
|
fix_case_list(CasesAssocList, GoalInfo, CasesList),
|
|
!:Requant = yes
|
|
;
|
|
Left = Left1,
|
|
fix_case_list(CasesAssocList1, GoalInfo, CasesList)
|
|
)
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred expand_sub_disjs(prog_var::in, list(hlds_goal)::in,
|
|
cases::in, cases::out) is semidet.
|
|
|
|
expand_sub_disjs(_Var, [], !Cases).
|
|
expand_sub_disjs(Var, [LeftGoal | LeftGoals], !Cases) :-
|
|
expand_sub_disj(Var, LeftGoal, !Cases),
|
|
expand_sub_disjs(Var, LeftGoals, !Cases).
|
|
|
|
:- pred expand_sub_disj(prog_var::in, hlds_goal::in, cases::in, cases::out)
|
|
is semidet.
|
|
|
|
expand_sub_disj(Var, Goal, !Cases) :-
|
|
Goal = GoalExpr - GoalInfo,
|
|
( GoalExpr = conj(SubGoals) ->
|
|
expand_sub_disj_process_conj(Var, SubGoals, [], GoalInfo, !Cases)
|
|
; GoalExpr = disj(_) ->
|
|
expand_sub_disj_process_conj(Var, [Goal], [], GoalInfo, !Cases)
|
|
;
|
|
fail
|
|
).
|
|
|
|
:- pred expand_sub_disj_process_conj(prog_var::in, list(hlds_goal)::in,
|
|
list(hlds_goal)::in, hlds_goal_info::in, cases::in, cases::out) is semidet.
|
|
|
|
expand_sub_disj_process_conj(Var, ConjGoals, !.RevUnifies, GoalInfo,
|
|
!Cases) :-
|
|
(
|
|
ConjGoals = [],
|
|
fail
|
|
;
|
|
ConjGoals = [FirstGoal | RestGoals],
|
|
FirstGoal = FirstGoalExpr - _,
|
|
( FirstGoalExpr = unify(_, _, _, _, _) ->
|
|
!:RevUnifies = [FirstGoal | !.RevUnifies],
|
|
expand_sub_disj_process_conj(Var, RestGoals, !.RevUnifies,
|
|
GoalInfo, !Cases)
|
|
; FirstGoalExpr = disj(Disjuncts) ->
|
|
Disjuncts = [_ | _],
|
|
list__reverse(!.RevUnifies, Unifies),
|
|
list__map(
|
|
create_expanded_conjunction(Unifies, RestGoals, GoalInfo),
|
|
Disjuncts, ExpandedConjunctions),
|
|
partition_disj_trial(ExpandedConjunctions, Var, [], Left, !Cases),
|
|
Left = []
|
|
;
|
|
fail
|
|
)
|
|
).
|
|
|
|
:- pred create_expanded_conjunction(list(hlds_goal)::in, list(hlds_goal)::in,
|
|
hlds_goal_info::in, hlds_goal::in, hlds_goal::out) is det.
|
|
|
|
create_expanded_conjunction(Unifies, RestGoals, GoalInfo, Disjunct, Goal) :-
|
|
( Disjunct = conj(DisjunctGoals) - _ ->
|
|
Conjuncts = Unifies ++ DisjunctGoals ++ RestGoals
|
|
;
|
|
Conjuncts = Unifies ++ [Disjunct] ++ RestGoals
|
|
),
|
|
Goal = conj(Conjuncts) - GoalInfo.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred partition_disj_trial(list(hlds_goal)::in, prog_var::in,
|
|
list(hlds_goal)::in, list(hlds_goal)::out,
|
|
cases::in, cases::out) is det.
|
|
|
|
partition_disj_trial([], _Var, !Left, !Cases).
|
|
partition_disj_trial([Goal0 | Goals], Var, !Left, !Cases) :-
|
|
find_bind_var(Var, find_bind_var_for_switch_in_deconstruct, Goal0, Goal,
|
|
no, MaybeFunctor, unit, _, _),
|
|
(
|
|
MaybeFunctor = yes(Functor),
|
|
( map__search(!.Cases, Functor, DisjList0) ->
|
|
DisjList = [Goal | DisjList0],
|
|
map__det_update(!.Cases, Functor, DisjList, !:Cases)
|
|
;
|
|
DisjList = [Goal],
|
|
map__det_insert(!.Cases, Functor, DisjList, !:Cases)
|
|
)
|
|
;
|
|
MaybeFunctor = no,
|
|
!:Left = [Goal0 | !.Left]
|
|
),
|
|
partition_disj_trial(Goals, Var, !Left, !Cases).
|
|
|
|
:- pred find_bind_var_for_switch_in_deconstruct(prog_var::in, hlds_goal::in,
|
|
list(hlds_goal)::out, maybe(cons_id)::in, maybe(cons_id)::out,
|
|
unit::in, unit::out) is det.
|
|
|
|
find_bind_var_for_switch_in_deconstruct(_UnifyVar, Goal0, Goals,
|
|
_Result0, Result, _, unit) :-
|
|
(
|
|
Goal0 = GoalExpr0 - GoalInfo,
|
|
UnifyInfo0 = GoalExpr0 ^ unify_kind,
|
|
UnifyInfo0 = deconstruct(_, Functor, _, _, _, _)
|
|
->
|
|
Result = yes(Functor),
|
|
% The deconstruction unification now becomes deterministic, since
|
|
% the test will get carried out in the switch.
|
|
UnifyInfo = UnifyInfo0 ^ deconstruct_can_fail := cannot_fail,
|
|
GoalExpr = GoalExpr0 ^ unify_kind := UnifyInfo,
|
|
Goal = GoalExpr - GoalInfo,
|
|
Goals = [Goal]
|
|
;
|
|
unexpected(this_file, "find_bind_var_for_switch_in_deconstruct")
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
find_bind_var(Var, ProcessUnify, !Goal, !Result, !Info, FoundDeconstruct) :-
|
|
map__init(Subst),
|
|
find_bind_var_2(Var, ProcessUnify, !Goal, Subst, _, !Result, !Info,
|
|
DeconstructSearch),
|
|
(
|
|
DeconstructSearch = before_deconstruct,
|
|
FoundDeconstruct = no
|
|
;
|
|
DeconstructSearch = found_deconstruct,
|
|
FoundDeconstruct = yes
|
|
;
|
|
DeconstructSearch = given_up_search,
|
|
FoundDeconstruct = no
|
|
).
|
|
|
|
:- type deconstruct_search
|
|
---> before_deconstruct
|
|
; found_deconstruct
|
|
; given_up_search.
|
|
|
|
:- pred find_bind_var_2(prog_var::in,
|
|
process_unify(Result, Info)::in(process_unify),
|
|
hlds_goal::in, hlds_goal::out,
|
|
prog_substitution::in, prog_substitution::out, Result::in, Result::out,
|
|
Info::in, Info::out, deconstruct_search::out) is det.
|
|
|
|
find_bind_var_2(Var, ProcessUnify, Goal0 - GoalInfo, Goal, !Subst, !Result,
|
|
!Info, FoundDeconstruct) :-
|
|
( Goal0 = scope(Reason, SubGoal0) ->
|
|
find_bind_var_2(Var, ProcessUnify, SubGoal0, SubGoal, !Subst,
|
|
!Result, !Info, FoundDeconstruct),
|
|
Goal = scope(Reason, SubGoal) - GoalInfo
|
|
; Goal0 = conj(SubGoals0) ->
|
|
(
|
|
SubGoals0 = [],
|
|
Goal = Goal0 - GoalInfo,
|
|
FoundDeconstruct = before_deconstruct
|
|
;
|
|
SubGoals0 = [_ | _],
|
|
conj_find_bind_var(Var, ProcessUnify, SubGoals0, SubGoals,
|
|
!Subst, !Result, !Info, FoundDeconstruct),
|
|
Goal = conj(SubGoals) - GoalInfo
|
|
)
|
|
; Goal0 = unify(LHS, RHS, _, UnifyInfo0, _) ->
|
|
(
|
|
% Check whether the unification is a deconstruction unification
|
|
% on either Var or on a variable aliased to Var.
|
|
UnifyInfo0 = deconstruct(UnifyVar, _, _, _, _, _),
|
|
term__apply_rec_substitution(term__variable(Var),
|
|
!.Subst, term__variable(SubstVar)),
|
|
term__apply_rec_substitution(term__variable(UnifyVar),
|
|
!.Subst, term__variable(SubstUnifyVar)),
|
|
SubstVar = SubstUnifyVar
|
|
->
|
|
call(ProcessUnify, Var, Goal0 - GoalInfo, Goals, !Result, !Info),
|
|
conj_list_to_goal(Goals, GoalInfo, Goal),
|
|
FoundDeconstruct = found_deconstruct
|
|
;
|
|
Goal = Goal0 - GoalInfo,
|
|
FoundDeconstruct = before_deconstruct,
|
|
% Otherwise abstractly interpret the unification.
|
|
( interpret_unify(LHS, RHS, !.Subst, NewSubst) ->
|
|
!:Subst = NewSubst
|
|
;
|
|
% The unification must fail - just ignore it.
|
|
true
|
|
)
|
|
)
|
|
;
|
|
Goal = Goal0 - GoalInfo,
|
|
( goal_info_has_feature(GoalInfo, from_head) ->
|
|
FoundDeconstruct = before_deconstruct
|
|
;
|
|
FoundDeconstruct = given_up_search
|
|
)
|
|
).
|
|
|
|
:- pred conj_find_bind_var(prog_var::in,
|
|
process_unify(Result, Info)::in(process_unify),
|
|
list(hlds_goal)::in, list(hlds_goal)::out,
|
|
prog_substitution::in, prog_substitution::out, Result::in, Result::out,
|
|
Info::in, Info::out, deconstruct_search::out) is det.
|
|
|
|
conj_find_bind_var(_Var, _, [], [], !Subst, !Result, !Info,
|
|
before_deconstruct).
|
|
conj_find_bind_var(Var, ProcessUnify, [Goal0 | Goals0], [Goal | Goals],
|
|
!Subst, !Result, !Info, FoundDeconstruct) :-
|
|
find_bind_var_2(Var, ProcessUnify, Goal0, Goal, !Subst,
|
|
!Result, !Info, FoundDeconstruct1),
|
|
( FoundDeconstruct1 = before_deconstruct ->
|
|
conj_find_bind_var(Var, ProcessUnify, Goals0, Goals,
|
|
!Subst, !Result, !Info, FoundDeconstruct)
|
|
;
|
|
FoundDeconstruct = FoundDeconstruct1,
|
|
Goals = Goals0
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred cases_to_switch(sorted_case_list::in, prog_var::in, vartypes::in,
|
|
hlds_goal_info::in, instmap::in, module_info::in, hlds_goal_expr::out,
|
|
bool::in, bool::out) is det.
|
|
|
|
cases_to_switch(CasesList, Var, VarTypes, _GoalInfo, InstMap, ModuleInfo,
|
|
Goal, !Requant) :-
|
|
instmap__lookup_var(InstMap, Var, VarInst),
|
|
( inst_is_bound_to_functors(ModuleInfo, VarInst, Functors) ->
|
|
functors_to_cons_ids(Functors, ConsIds0),
|
|
list__sort(ConsIds0, ConsIds),
|
|
delete_unreachable_cases(CasesList, ConsIds, CasesList1),
|
|
( list__same_length(Functors, CasesList1) ->
|
|
CanFail = cannot_fail
|
|
;
|
|
CanFail = can_fail
|
|
)
|
|
;
|
|
map__lookup(VarTypes, Var, Type),
|
|
CasesList1 = CasesList,
|
|
( switch_covers_all_cases(ModuleInfo, Type, CasesList1) ->
|
|
CanFail = cannot_fail
|
|
;
|
|
CanFail = can_fail
|
|
)
|
|
),
|
|
detect_switches_in_cases(ModuleInfo, VarTypes, InstMap,
|
|
CasesList1, Cases, !Requant),
|
|
|
|
% We turn switches with no arms into fail, since this avoids having
|
|
% the code generator flush the control variable of the switch.
|
|
% We can't easily eliminate switches with one arm, since the
|
|
% code of the arm will have the unification between the variable
|
|
% and the function symbol as det. The gain would be minimal to
|
|
% nonexistent anyway.
|
|
(
|
|
Cases = [],
|
|
Goal = disj([])
|
|
;
|
|
Cases = [_ | _],
|
|
Goal = switch(Var, CanFail, Cases)
|
|
).
|
|
|
|
% Check whether a switch handles all the possible constants/functors
|
|
% for the type.
|
|
%
|
|
:- pred switch_covers_all_cases(module_info::in, mer_type::in,
|
|
sorted_case_list::in) is semidet.
|
|
|
|
switch_covers_all_cases(ModuleInfo, Type, CasesList) :-
|
|
type_util__switch_type_num_functors(ModuleInfo, Type, NumFunctors),
|
|
list__length(CasesList, NumCases),
|
|
NumCases = NumFunctors.
|
|
|
|
% Convert the assoc_list(cons_id, list(hlds_goal)) back into a plain
|
|
% list(case).
|
|
%
|
|
:- pred fix_case_list(assoc_list(cons_id, list(hlds_goal))::in,
|
|
hlds_goal_info::in, list(case)::out) is det.
|
|
|
|
fix_case_list([], _, []).
|
|
fix_case_list([Functor - DisjList0 | Cases0], GoalInfo,
|
|
[case(Functor, Goal) | Cases]) :-
|
|
% We need to put the list back the right way around.
|
|
list__reverse(DisjList0, DisjList),
|
|
disj_list_to_goal(DisjList, GoalInfo, Goal),
|
|
fix_case_list(Cases0, GoalInfo, Cases).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- func this_file = string.
|
|
|
|
this_file = "switch_detection.m".
|
|
|
|
%-----------------------------------------------------------------------------%
|