mirror of
https://github.com/Mercury-Language/mercury.git
synced 2026-04-15 17:33:38 +00:00
426 lines
17 KiB
Mathematica
426 lines
17 KiB
Mathematica
%-----------------------------------------------------------------------------%
|
|
% vim: ft=mercury ts=4 sw=4 et
|
|
%-----------------------------------------------------------------------------%
|
|
% Copyright (C) 1994-2012 The University of Melbourne.
|
|
% This file may only be copied under the terms of the GNU General
|
|
% Public License - see the file COPYING in the Mercury distribution.
|
|
%-----------------------------------------------------------------------------%
|
|
%
|
|
% File: follow_code.m.
|
|
% Main author: conway.
|
|
% Extensive modifications by zs.
|
|
%
|
|
% The problem attacked by this module is that sometimes the code generator
|
|
% doesn't know where it should put the values of live variables at the end
|
|
% of a branched control structure. All branches must put each live variable
|
|
% into the same lval, so having each branch leave each live variable where it
|
|
% just happens to be is not an option. We currently just put all live variables
|
|
% into its own rN register or stack slot, but often is not where the variable
|
|
% happens to be at the end of any branch, nor is it where the variable is next
|
|
% needed.
|
|
%
|
|
% The idea used by this module to attack this problem is to try to ensure
|
|
% that the branched control structure is followed immediately either by a call
|
|
% or by the end of the procedure body, because both have clear rules about
|
|
% where every live variable must be. If a branched control structure is
|
|
% followed by builtin goals such as unifications, we push those goals into
|
|
% each branch.
|
|
%
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- module ll_backend.follow_code.
|
|
:- interface.
|
|
|
|
:- import_module hlds.
|
|
:- import_module hlds.hlds_module.
|
|
:- import_module hlds.hlds_pred.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_in_proc(pred_proc_id::in,
|
|
proc_info::in, proc_info::out, module_info::in, module_info::out) is det.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- implementation.
|
|
|
|
:- import_module check_hlds.
|
|
:- import_module check_hlds.mode_util.
|
|
:- import_module hlds.code_model.
|
|
:- import_module hlds.goal_util.
|
|
:- import_module hlds.hlds_goal.
|
|
:- import_module hlds.hlds_rtti.
|
|
:- import_module hlds.instmap.
|
|
:- import_module hlds.quantification.
|
|
:- import_module parse_tree.
|
|
:- import_module parse_tree.prog_data.
|
|
:- import_module parse_tree.prog_detism.
|
|
:- import_module parse_tree.set_of_var.
|
|
|
|
:- import_module bool.
|
|
:- import_module list.
|
|
:- import_module require.
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
move_follow_code_in_proc(_PredProcId, !ProcInfo, !ModuleInfo) :-
|
|
proc_info_get_goal(!.ProcInfo, Goal0),
|
|
proc_info_get_varset(!.ProcInfo, Varset0),
|
|
proc_info_get_vartypes(!.ProcInfo, VarTypes0),
|
|
proc_info_get_rtti_varmaps(!.ProcInfo, RttiVarMaps0),
|
|
move_follow_code_in_goal(Goal0, Goal1, RttiVarMaps0, no, Changed),
|
|
(
|
|
Changed = yes,
|
|
% We need to fix up the goal_info by recalculating the nonlocal
|
|
% vars and the non-atomic instmap deltas.
|
|
proc_info_get_headvars(!.ProcInfo, HeadVars),
|
|
implicitly_quantify_clause_body_general(
|
|
ordinary_nonlocals_no_lambda,
|
|
HeadVars, _Warnings, Goal1, Goal2,
|
|
Varset0, Varset, VarTypes0, VarTypes,
|
|
RttiVarMaps0, RttiVarMaps),
|
|
proc_info_get_initial_instmap(!.ProcInfo, !.ModuleInfo, InstMap0),
|
|
proc_info_get_inst_varset(!.ProcInfo, InstVarSet),
|
|
recompute_instmap_delta(do_not_recompute_atomic_instmap_deltas,
|
|
Goal2, Goal, VarTypes, InstVarSet, InstMap0, !ModuleInfo),
|
|
proc_info_set_goal(Goal, !ProcInfo),
|
|
proc_info_set_varset(Varset, !ProcInfo),
|
|
proc_info_set_vartypes(VarTypes, !ProcInfo),
|
|
proc_info_set_rtti_varmaps(RttiVarMaps, !ProcInfo)
|
|
;
|
|
Changed = no
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_in_goal(hlds_goal::in, hlds_goal::out,
|
|
rtti_varmaps::in, bool::in, bool::out) is det.
|
|
|
|
move_follow_code_in_goal(Goal0, Goal, RttiVarMaps, !Changed) :-
|
|
Goal0 = hlds_goal(GoalExpr0, GoalInfo),
|
|
(
|
|
GoalExpr0 = conj(ConjType, Goals0),
|
|
(
|
|
ConjType = plain_conj,
|
|
ConjPurity = goal_info_get_purity(GoalInfo),
|
|
move_follow_code_in_conj(Goals0, ConjPurity, RttiVarMaps, Goals,
|
|
!Changed)
|
|
;
|
|
ConjType = parallel_conj,
|
|
move_follow_code_in_independent_goals(Goals0, Goals, RttiVarMaps,
|
|
!Changed)
|
|
),
|
|
GoalExpr = conj(ConjType, Goals),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
;
|
|
GoalExpr0 = disj(Goals0),
|
|
move_follow_code_in_independent_goals(Goals0, Goals, RttiVarMaps,
|
|
!Changed),
|
|
GoalExpr = disj(Goals),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
;
|
|
GoalExpr0 = negation(SubGoal0),
|
|
move_follow_code_in_goal(SubGoal0, SubGoal, RttiVarMaps, !Changed),
|
|
GoalExpr = negation(SubGoal),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
;
|
|
GoalExpr0 = switch(Var, Det, Cases0),
|
|
move_follow_code_in_cases(Cases0, Cases, RttiVarMaps, !Changed),
|
|
GoalExpr = switch(Var, Det, Cases),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
;
|
|
GoalExpr0 = if_then_else(Vars, Cond0, Then0, Else0),
|
|
move_follow_code_in_goal(Cond0, Cond, RttiVarMaps, !Changed),
|
|
move_follow_code_in_goal(Then0, Then, RttiVarMaps, !Changed),
|
|
move_follow_code_in_goal(Else0, Else, RttiVarMaps, !Changed),
|
|
GoalExpr = if_then_else(Vars, Cond, Then, Else),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
;
|
|
GoalExpr0 = scope(Reason, SubGoal0),
|
|
( if
|
|
Reason = from_ground_term(_, FGT),
|
|
( FGT = from_ground_term_construct
|
|
; FGT = from_ground_term_deconstruct
|
|
)
|
|
then
|
|
SubGoal = SubGoal0
|
|
else
|
|
move_follow_code_in_goal(SubGoal0, SubGoal, RttiVarMaps, !Changed)
|
|
),
|
|
GoalExpr = scope(Reason, SubGoal),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
;
|
|
( GoalExpr0 = generic_call(_, _, _, _, _)
|
|
; GoalExpr0 = plain_call(_, _, _, _, _, _)
|
|
; GoalExpr0 = unify(_, _, _, _, _)
|
|
; GoalExpr0 = call_foreign_proc(_, _, _, _, _, _, _)
|
|
),
|
|
Goal = Goal0
|
|
;
|
|
GoalExpr0 = shorthand(_),
|
|
% These should have been expanded out by now.
|
|
unexpected($pred, "shorthand")
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
% move_follow_code_in_independent_goals is used both for disjunction and
|
|
% parallel conjunction.
|
|
%
|
|
:- pred move_follow_code_in_independent_goals(list(hlds_goal)::in,
|
|
list(hlds_goal)::out, rtti_varmaps::in, bool::in, bool::out) is det.
|
|
|
|
move_follow_code_in_independent_goals([], [], _, !Changed).
|
|
move_follow_code_in_independent_goals([Goal0 | Goals0], [Goal | Goals],
|
|
RttiVarMaps, !Changed) :-
|
|
move_follow_code_in_goal(Goal0, Goal, RttiVarMaps, !Changed),
|
|
move_follow_code_in_independent_goals(Goals0, Goals,
|
|
RttiVarMaps, !Changed).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_in_cases(list(case)::in, list(case)::out,
|
|
rtti_varmaps::in, bool::in, bool::out) is det.
|
|
|
|
move_follow_code_in_cases([], [], _, !Changed).
|
|
move_follow_code_in_cases([Case0 | Cases0], [Case | Cases], RttiVarMaps,
|
|
!Changed) :-
|
|
Case0 = case(MainConsId, OtherConsIds, Goal0),
|
|
move_follow_code_in_goal(Goal0, Goal, RttiVarMaps, !Changed),
|
|
Case = case(MainConsId, OtherConsIds, Goal),
|
|
move_follow_code_in_cases(Cases0, Cases, RttiVarMaps, !Changed).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
% Find the first branched structure, and split the conj into those goals
|
|
% before and after it.
|
|
%
|
|
:- pred move_follow_code_in_conj(list(hlds_goal)::in, purity::in,
|
|
rtti_varmaps::in, list(hlds_goal)::out, bool::in, bool::out) is det.
|
|
|
|
move_follow_code_in_conj(Goals0, ConjPurity, RttiVarMaps, Goals, !Changed) :-
|
|
move_follow_code_in_conj_2(Goals0, ConjPurity, RttiVarMaps, [], RevGoals,
|
|
!Changed),
|
|
list.reverse(RevGoals, Goals).
|
|
|
|
:- pred move_follow_code_in_conj_2(list(hlds_goal)::in, purity::in,
|
|
rtti_varmaps::in, list(hlds_goal)::in, list(hlds_goal)::out,
|
|
bool::in, bool::out) is det.
|
|
|
|
move_follow_code_in_conj_2([], _ConjPurity, _RttiVarMaps, !RevPrevGoals,
|
|
!Changed).
|
|
move_follow_code_in_conj_2([Goal0 | Goals0], ConjPurity, RttiVarMaps,
|
|
!RevPrevGoals, !Changed) :-
|
|
( if
|
|
Goal0 = hlds_goal(GoalExpr0, GoalInfo0),
|
|
goal_util.goal_is_branched(GoalExpr0),
|
|
% A goal that has the mode_check_clauses marker on it will not
|
|
% have its set of output variables updated by recompute_instmap_delta.
|
|
% If we move new code into it, this lack of recomputation will
|
|
% be a bug if that code binds any variables, which it almost certainly
|
|
% will.
|
|
not goal_info_has_feature(GoalInfo0, feature_mode_check_clauses_goal),
|
|
|
|
move_follow_code_select(Goals0, RttiVarMaps, FollowGoals,
|
|
RestGoalsPrime, ConjPurity, WorstPurity),
|
|
FollowGoals = [_ | _],
|
|
% Moving any goals that bind variables into a model_semi (or model_det)
|
|
% disjunction gives that disjunction some outputs, which means that it
|
|
% will become nondet.
|
|
(
|
|
(
|
|
GoalExpr0 = disj(_),
|
|
goal_info_get_code_model(GoalInfo0) \= model_non
|
|
)
|
|
=>
|
|
no_bind_vars(FollowGoals)
|
|
),
|
|
move_follow_code_move_goals(Goal0, FollowGoals, WorstPurity,
|
|
Goal1Prime)
|
|
then
|
|
!:Changed = yes,
|
|
Goal1 = Goal1Prime,
|
|
RestGoals = RestGoalsPrime
|
|
else
|
|
Goal1 = Goal0,
|
|
RestGoals = Goals0
|
|
),
|
|
move_follow_code_in_goal(Goal1, Goal, RttiVarMaps, !Changed),
|
|
!:RevPrevGoals = [Goal | !.RevPrevGoals],
|
|
move_follow_code_in_conj_2(RestGoals, ConjPurity, RttiVarMaps,
|
|
!RevPrevGoals, !Changed).
|
|
|
|
:- pred no_bind_vars(list(hlds_goal)::in) is semidet.
|
|
|
|
no_bind_vars([]).
|
|
no_bind_vars([Goal | Goals]) :-
|
|
Goal = hlds_goal(_, GoalInfo),
|
|
InstMapDelta = goal_info_get_instmap_delta(GoalInfo),
|
|
instmap_delta_changed_vars(InstMapDelta, ChangedVars),
|
|
set_of_var.is_empty(ChangedVars),
|
|
no_bind_vars(Goals).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
% Split a list of goals into the prefix of builtins and the rest.
|
|
%
|
|
:- pred move_follow_code_select(list(hlds_goal)::in, rtti_varmaps::in,
|
|
list(hlds_goal)::out, list(hlds_goal)::out, purity::in, purity::out)
|
|
is det.
|
|
|
|
move_follow_code_select([], _, [], [], !Purity).
|
|
move_follow_code_select([Goal | Goals], RttiVarMaps, FollowGoals, RestGoals,
|
|
!Purity) :-
|
|
Goal = hlds_goal(GoalExpr, GoalInfo),
|
|
( if
|
|
move_follow_code_is_builtin(GoalExpr),
|
|
|
|
% Don't attempt to move existentially typed deconstructions
|
|
% into branched structures. Doing so would confuse the
|
|
% rtti_varmaps structure, which expects type(class)_infos
|
|
% for a given type variable (constraint) to be retrieved from
|
|
% a single location.
|
|
%
|
|
% XXX A better solution might be to introduce exists_cast goals,
|
|
% which would allow separate type variables for each branch and
|
|
% avoid the above confusion.
|
|
%
|
|
not (
|
|
GoalExpr = unify(_, _, _, Unification, _),
|
|
Unification = deconstruct(_, _, Args, _, _, _),
|
|
list.member(Arg, Args),
|
|
rtti_varmaps_var_info(RttiVarMaps, Arg, RttiVarInfo),
|
|
RttiVarInfo \= non_rtti_var
|
|
)
|
|
then
|
|
GoalPurity = goal_info_get_purity(GoalInfo),
|
|
!:Purity = worst_purity(!.Purity, GoalPurity),
|
|
move_follow_code_select(Goals, RttiVarMaps, FollowGoals0, RestGoals,
|
|
!Purity),
|
|
FollowGoals = [Goal | FollowGoals0]
|
|
else
|
|
FollowGoals = [],
|
|
RestGoals = [Goal | Goals]
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_move_goals(hlds_goal::in, list(hlds_goal)::in,
|
|
purity::in, hlds_goal::out) is semidet.
|
|
|
|
move_follow_code_move_goals(Goal0, FollowGoals, FollowPurity, Goal) :-
|
|
Goal0 = hlds_goal(GoalExpr0, GoalInfo0),
|
|
(
|
|
GoalExpr0 = switch(Var, Det, Cases0),
|
|
move_follow_code_move_goals_cases(Cases0, FollowGoals, FollowPurity,
|
|
Cases),
|
|
GoalExpr = switch(Var, Det, Cases)
|
|
;
|
|
GoalExpr0 = disj(Goals0),
|
|
move_follow_code_move_goals_disj(Goals0, FollowGoals, FollowPurity,
|
|
Goals),
|
|
GoalExpr = disj(Goals)
|
|
;
|
|
GoalExpr0 = if_then_else(Vars, Cond, Then0, Else0),
|
|
follow_code_conjoin_goal_and_goal_list(Then0, FollowGoals,
|
|
FollowPurity, Then),
|
|
follow_code_conjoin_goal_and_goal_list(Else0, FollowGoals,
|
|
FollowPurity, Else),
|
|
GoalExpr = if_then_else(Vars, Cond, Then, Else)
|
|
),
|
|
OldPurity = goal_info_get_purity(GoalInfo0),
|
|
NewPurity = worst_purity(OldPurity, FollowPurity),
|
|
goal_info_set_purity(NewPurity, GoalInfo0, GoalInfo),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_move_goals_cases(list(case)::in, list(hlds_goal)::in,
|
|
purity::in, list(case)::out) is semidet.
|
|
|
|
move_follow_code_move_goals_cases([], _FollowGoals, _FollowPurity, []).
|
|
move_follow_code_move_goals_cases([Case0 | Cases0], FollowGoals, FollowPurity,
|
|
[Case | Cases]) :-
|
|
Case0 = case(MainConsId, OtherConsIds, Goal0),
|
|
follow_code_conjoin_goal_and_goal_list(Goal0, FollowGoals, FollowPurity,
|
|
Goal),
|
|
Case = case(MainConsId, OtherConsIds, Goal),
|
|
move_follow_code_move_goals_cases(Cases0, FollowGoals, FollowPurity,
|
|
Cases).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_move_goals_disj(list(hlds_goal)::in,
|
|
list(hlds_goal)::in, purity::in, list(hlds_goal)::out) is semidet.
|
|
|
|
move_follow_code_move_goals_disj([], _FollowGoals, _FollowPurity, []).
|
|
move_follow_code_move_goals_disj([Goal0 | Goals0], FollowGoals, FollowPurity,
|
|
[Goal | Goals]) :-
|
|
follow_code_conjoin_goal_and_goal_list(Goal0, FollowGoals, FollowPurity,
|
|
Goal),
|
|
move_follow_code_move_goals_disj(Goals0, FollowGoals, FollowPurity, Goals).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
% Takes a goal and a list of goals, and conjoins them (with a potentially
|
|
% blank goal_info), checking that the determinism of the goal is not
|
|
% changed.
|
|
%
|
|
:- pred follow_code_conjoin_goal_and_goal_list(hlds_goal::in,
|
|
list(hlds_goal)::in, purity::in, hlds_goal::out) is semidet.
|
|
|
|
follow_code_conjoin_goal_and_goal_list(Goal0, FollowGoals, FollowPurity,
|
|
Goal) :-
|
|
Goal0 = hlds_goal(GoalExpr0, GoalInfo0),
|
|
Detism0 = goal_info_get_determinism(GoalInfo0),
|
|
determinism_components(Detism0, _CanFail0, MaxSolns0),
|
|
(
|
|
MaxSolns0 = at_most_zero,
|
|
Goal = Goal0
|
|
;
|
|
( MaxSolns0 = at_most_one
|
|
; MaxSolns0 = at_most_many
|
|
; MaxSolns0 = at_most_many_cc
|
|
),
|
|
check_follow_code_detism(FollowGoals, Detism0),
|
|
( if GoalExpr0 = conj(plain_conj, Conjuncts0) then
|
|
GoalExpr = conj(plain_conj, Conjuncts0 ++ FollowGoals)
|
|
else
|
|
GoalExpr = conj(plain_conj, [Goal0 | FollowGoals])
|
|
),
|
|
OldPurity = goal_info_get_purity(GoalInfo0),
|
|
NewPurity = worst_purity(OldPurity, FollowPurity),
|
|
goal_info_set_purity(NewPurity, GoalInfo0, GoalInfo),
|
|
Goal = hlds_goal(GoalExpr, GoalInfo)
|
|
).
|
|
|
|
% This check is necessary to make sure that follow_code doesn't change
|
|
% the determinism of the goal.
|
|
%
|
|
:- pred check_follow_code_detism(list(hlds_goal)::in, determinism::in)
|
|
is semidet.
|
|
|
|
check_follow_code_detism([], _).
|
|
check_follow_code_detism([hlds_goal(_, GoalInfo) | Goals], Detism0) :-
|
|
Detism1 = goal_info_get_determinism(GoalInfo),
|
|
det_conjunction_detism(Detism0, Detism1, Detism0),
|
|
check_follow_code_detism(Goals, Detism0).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
|
|
:- pred move_follow_code_is_builtin(hlds_goal_expr::in) is semidet.
|
|
|
|
move_follow_code_is_builtin(GoalExpr) :-
|
|
(
|
|
GoalExpr = unify(_, _, _, Unification, _),
|
|
Unification \= complicated_unify(_, _, _)
|
|
;
|
|
GoalExpr = plain_call(_, _, _, inline_builtin, _, _)
|
|
).
|
|
|
|
%-----------------------------------------------------------------------------%
|
|
:- end_module ll_backend.follow_code.
|
|
%-----------------------------------------------------------------------------%
|