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cc9912faa8
Packages are modules whose only job is to serve as a container for submodules. Modules like top_level.m, hlds.m, parse_tree.m and ll_backend.m are packages in this (informal) sense. Besides the include_module declarations for their submodules, most of the packages in the compiler used to import some modules, mostly other packages whose component modules their submodules may need. For example, ll_backend.m used to import parse_tree.m. This meant that modules in the ll_backend package did not have to import parse_tree.m before importing modules in the parse_tree package. However, this had a price. When we add a new module to the parse_tree package, parse_tree.int would change, and this would require the recompilation of ALL the modules in the ll_backend package, even the ones that did NOT import ANY of the modules in the parse_tree package. This happened even at one remove. Pretty much all modules in every one of the backend have to import one or more modules in the hlds package, and they therefore have import hlds.m. Since hlds.m imported transform_hlds.m, any addition of a new middle pass to the transform_hlds package required the recompilation of all backend modules, even in the usual case of the two having nothing to do with each other. This diff removes all import_module declarations from the packages, and replaces them with import_module declarations in the modules that need them. This includes only a SUBSET of their child modules and of the non-child modules that import them.
426 lines
17 KiB
Mathematica
426 lines
17 KiB
Mathematica
%-----------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%-----------------------------------------------------------------------------%
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% Copyright (C) 1994-2012 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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% File: follow_code.m.
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% Main author: conway.
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% Extensive modifications by zs.
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%
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% The problem attacked by this module is that sometimes the code generator
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% doesn't know where it should put the values of live variables at the end
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% of a branched control structure. All branches must put each live variable
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% into the same lval, so having each branch leave each live variable where it
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% just happens to be is not an option. We currently just put all live variables
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% into its own rN register or stack slot, but often is not where the variable
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% happens to be at the end of any branch, nor is it where the variable is next
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% needed.
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%
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% The idea used by this module to attack this problem is to try to ensure
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% that the branched control structure is followed immediately either by a call
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% or by the end of the procedure body, because both have clear rules about
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% where every live variable must be. If a branched control structure is
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% followed by builtin goals such as unifications, we push those goals into
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% each branch.
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%
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%-----------------------------------------------------------------------------%
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:- module ll_backend.follow_code.
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:- interface.
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:- import_module hlds.
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:- import_module hlds.hlds_module.
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:- import_module hlds.hlds_pred.
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_in_proc(pred_proc_id::in,
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proc_info::in, proc_info::out, module_info::in, module_info::out) is det.
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- implementation.
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:- import_module check_hlds.
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:- import_module check_hlds.mode_util.
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:- import_module hlds.code_model.
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:- import_module hlds.goal_util.
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:- import_module hlds.hlds_goal.
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:- import_module hlds.hlds_rtti.
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:- import_module hlds.instmap.
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:- import_module hlds.quantification.
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:- import_module parse_tree.
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:- import_module parse_tree.prog_data.
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:- import_module parse_tree.prog_detism.
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:- import_module parse_tree.set_of_var.
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:- import_module bool.
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:- import_module list.
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:- import_module require.
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%-----------------------------------------------------------------------------%
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move_follow_code_in_proc(_PredProcId, !ProcInfo, !ModuleInfo) :-
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proc_info_get_goal(!.ProcInfo, Goal0),
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proc_info_get_varset(!.ProcInfo, Varset0),
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proc_info_get_vartypes(!.ProcInfo, VarTypes0),
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proc_info_get_rtti_varmaps(!.ProcInfo, RttiVarMaps0),
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move_follow_code_in_goal(Goal0, Goal1, RttiVarMaps0, no, Changed),
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(
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Changed = yes,
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% We need to fix up the goal_info by recalculating the nonlocal
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% vars and the non-atomic instmap deltas.
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proc_info_get_headvars(!.ProcInfo, HeadVars),
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implicitly_quantify_clause_body_general(
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ordinary_nonlocals_no_lambda,
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HeadVars, _Warnings, Goal1, Goal2,
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Varset0, Varset, VarTypes0, VarTypes,
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RttiVarMaps0, RttiVarMaps),
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proc_info_get_initial_instmap(!.ProcInfo, !.ModuleInfo, InstMap0),
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proc_info_get_inst_varset(!.ProcInfo, InstVarSet),
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recompute_instmap_delta(do_not_recompute_atomic_instmap_deltas,
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Goal2, Goal, VarTypes, InstVarSet, InstMap0, !ModuleInfo),
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proc_info_set_goal(Goal, !ProcInfo),
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proc_info_set_varset(Varset, !ProcInfo),
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proc_info_set_vartypes(VarTypes, !ProcInfo),
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proc_info_set_rtti_varmaps(RttiVarMaps, !ProcInfo)
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;
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Changed = no
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).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_in_goal(hlds_goal::in, hlds_goal::out,
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rtti_varmaps::in, bool::in, bool::out) is det.
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move_follow_code_in_goal(Goal0, Goal, RttiVarMaps, !Changed) :-
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Goal0 = hlds_goal(GoalExpr0, GoalInfo),
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(
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GoalExpr0 = conj(ConjType, Goals0),
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(
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ConjType = plain_conj,
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ConjPurity = goal_info_get_purity(GoalInfo),
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move_follow_code_in_conj(Goals0, ConjPurity, RttiVarMaps, Goals,
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!Changed)
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;
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ConjType = parallel_conj,
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move_follow_code_in_independent_goals(Goals0, Goals, RttiVarMaps,
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!Changed)
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),
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GoalExpr = conj(ConjType, Goals),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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;
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GoalExpr0 = disj(Goals0),
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move_follow_code_in_independent_goals(Goals0, Goals, RttiVarMaps,
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!Changed),
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GoalExpr = disj(Goals),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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;
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GoalExpr0 = negation(SubGoal0),
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move_follow_code_in_goal(SubGoal0, SubGoal, RttiVarMaps, !Changed),
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GoalExpr = negation(SubGoal),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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;
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GoalExpr0 = switch(Var, Det, Cases0),
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move_follow_code_in_cases(Cases0, Cases, RttiVarMaps, !Changed),
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GoalExpr = switch(Var, Det, Cases),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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;
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GoalExpr0 = if_then_else(Vars, Cond0, Then0, Else0),
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move_follow_code_in_goal(Cond0, Cond, RttiVarMaps, !Changed),
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move_follow_code_in_goal(Then0, Then, RttiVarMaps, !Changed),
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move_follow_code_in_goal(Else0, Else, RttiVarMaps, !Changed),
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GoalExpr = if_then_else(Vars, Cond, Then, Else),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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;
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GoalExpr0 = scope(Reason, SubGoal0),
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( if
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Reason = from_ground_term(_, FGT),
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( FGT = from_ground_term_construct
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; FGT = from_ground_term_deconstruct
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)
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then
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SubGoal = SubGoal0
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else
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move_follow_code_in_goal(SubGoal0, SubGoal, RttiVarMaps, !Changed)
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),
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GoalExpr = scope(Reason, SubGoal),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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;
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( GoalExpr0 = generic_call(_, _, _, _, _)
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; GoalExpr0 = plain_call(_, _, _, _, _, _)
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; GoalExpr0 = unify(_, _, _, _, _)
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; GoalExpr0 = call_foreign_proc(_, _, _, _, _, _, _)
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),
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Goal = Goal0
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;
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GoalExpr0 = shorthand(_),
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% These should have been expanded out by now.
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unexpected($module, $pred, "shorthand")
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).
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%-----------------------------------------------------------------------------%
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% move_follow_code_in_independent_goals is used both for disjunction and
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% parallel conjunction.
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%
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:- pred move_follow_code_in_independent_goals(list(hlds_goal)::in,
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list(hlds_goal)::out, rtti_varmaps::in, bool::in, bool::out) is det.
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move_follow_code_in_independent_goals([], [], _, !Changed).
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move_follow_code_in_independent_goals([Goal0 | Goals0], [Goal | Goals],
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RttiVarMaps, !Changed) :-
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move_follow_code_in_goal(Goal0, Goal, RttiVarMaps, !Changed),
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move_follow_code_in_independent_goals(Goals0, Goals, RttiVarMaps,
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!Changed).
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_in_cases(list(case)::in, list(case)::out,
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rtti_varmaps::in, bool::in, bool::out) is det.
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move_follow_code_in_cases([], [], _, !Changed).
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move_follow_code_in_cases([Case0 | Cases0], [Case | Cases], RttiVarMaps,
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!Changed) :-
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Case0 = case(MainConsId, OtherConsIds, Goal0),
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move_follow_code_in_goal(Goal0, Goal, RttiVarMaps, !Changed),
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Case = case(MainConsId, OtherConsIds, Goal),
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move_follow_code_in_cases(Cases0, Cases, RttiVarMaps, !Changed).
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%-----------------------------------------------------------------------------%
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% Find the first branched structure, and split the conj into those goals
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% before and after it.
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%
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:- pred move_follow_code_in_conj(list(hlds_goal)::in, purity::in,
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rtti_varmaps::in, list(hlds_goal)::out, bool::in, bool::out) is det.
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move_follow_code_in_conj(Goals0, ConjPurity, RttiVarMaps, Goals, !Changed) :-
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move_follow_code_in_conj_2(Goals0, ConjPurity, RttiVarMaps, [], RevGoals,
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!Changed),
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list.reverse(RevGoals, Goals).
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:- pred move_follow_code_in_conj_2(list(hlds_goal)::in, purity::in,
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rtti_varmaps::in, list(hlds_goal)::in, list(hlds_goal)::out,
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bool::in, bool::out) is det.
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move_follow_code_in_conj_2([], _ConjPurity, _RttiVarMaps, !RevPrevGoals,
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!Changed).
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move_follow_code_in_conj_2([Goal0 | Goals0], ConjPurity, RttiVarMaps,
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!RevPrevGoals, !Changed) :-
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( if
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Goal0 = hlds_goal(GoalExpr0, GoalInfo0),
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goal_util.goal_is_branched(GoalExpr0),
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% A goal that has the mode_check_clauses marker on it will not
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% have its set of output variables updated by recompute_instmap_delta.
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% If we move new code into it, this lack of recomputation will
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% be a bug if that code binds any variables, which it almost certainly
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% will.
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not goal_info_has_feature(GoalInfo0, feature_mode_check_clauses_goal),
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move_follow_code_select(Goals0, RttiVarMaps, FollowGoals,
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RestGoalsPrime, ConjPurity, WorstPurity),
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FollowGoals = [_ | _],
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% Moving any goals that bind variables into a model_semi (or model_det)
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% disjunction gives that disjunction some outputs, which means that it
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% will become nondet.
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(
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(
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GoalExpr0 = disj(_),
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goal_info_get_code_model(GoalInfo0) \= model_non
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)
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=>
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no_bind_vars(FollowGoals)
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),
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move_follow_code_move_goals(Goal0, FollowGoals, WorstPurity,
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Goal1Prime)
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then
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!:Changed = yes,
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Goal1 = Goal1Prime,
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RestGoals = RestGoalsPrime
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else
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Goal1 = Goal0,
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RestGoals = Goals0
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),
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move_follow_code_in_goal(Goal1, Goal, RttiVarMaps, !Changed),
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!:RevPrevGoals = [Goal | !.RevPrevGoals],
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move_follow_code_in_conj_2(RestGoals, ConjPurity, RttiVarMaps,
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!RevPrevGoals, !Changed).
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:- pred no_bind_vars(list(hlds_goal)::in) is semidet.
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no_bind_vars([]).
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no_bind_vars([Goal | Goals]) :-
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Goal = hlds_goal(_, GoalInfo),
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InstMapDelta = goal_info_get_instmap_delta(GoalInfo),
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instmap_delta_changed_vars(InstMapDelta, ChangedVars),
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set_of_var.is_empty(ChangedVars),
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no_bind_vars(Goals).
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%-----------------------------------------------------------------------------%
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% Split a list of goals into the prefix of builtins and the rest.
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%
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:- pred move_follow_code_select(list(hlds_goal)::in, rtti_varmaps::in,
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list(hlds_goal)::out, list(hlds_goal)::out, purity::in, purity::out)
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is det.
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move_follow_code_select([], _, [], [], !Purity).
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move_follow_code_select([Goal | Goals], RttiVarMaps, FollowGoals, RestGoals,
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!Purity) :-
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Goal = hlds_goal(GoalExpr, GoalInfo),
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( if
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move_follow_code_is_builtin(GoalExpr),
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% Don't attempt to move existentially typed deconstructions
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% into branched structures. Doing so would confuse the
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% rtti_varmaps structure, which expects type(class)_infos
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% for a given type variable (constraint) to be retrieved from
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% a single location.
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%
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% XXX A better solution might be to introduce exists_cast goals,
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% which would allow separate type variables for each branch and
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% avoid the above confusion.
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%
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not (
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GoalExpr = unify(_, _, _, Unification, _),
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Unification = deconstruct(_, _, Args, _, _, _),
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list.member(Arg, Args),
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rtti_varmaps_var_info(RttiVarMaps, Arg, RttiVarInfo),
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RttiVarInfo \= non_rtti_var
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)
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then
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GoalPurity = goal_info_get_purity(GoalInfo),
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!:Purity = worst_purity(!.Purity, GoalPurity),
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move_follow_code_select(Goals, RttiVarMaps, FollowGoals0, RestGoals,
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!Purity),
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FollowGoals = [Goal | FollowGoals0]
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else
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FollowGoals = [],
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RestGoals = [Goal | Goals]
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).
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_move_goals(hlds_goal::in, list(hlds_goal)::in,
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purity::in, hlds_goal::out) is semidet.
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move_follow_code_move_goals(Goal0, FollowGoals, FollowPurity, Goal) :-
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Goal0 = hlds_goal(GoalExpr0, GoalInfo0),
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(
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GoalExpr0 = switch(Var, Det, Cases0),
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move_follow_code_move_goals_cases(Cases0, FollowGoals, FollowPurity,
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Cases),
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GoalExpr = switch(Var, Det, Cases)
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;
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GoalExpr0 = disj(Goals0),
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move_follow_code_move_goals_disj(Goals0, FollowGoals, FollowPurity,
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Goals),
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GoalExpr = disj(Goals)
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;
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GoalExpr0 = if_then_else(Vars, Cond, Then0, Else0),
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follow_code_conjoin_goal_and_goal_list(Then0, FollowGoals,
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FollowPurity, Then),
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follow_code_conjoin_goal_and_goal_list(Else0, FollowGoals,
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FollowPurity, Else),
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GoalExpr = if_then_else(Vars, Cond, Then, Else)
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),
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OldPurity = goal_info_get_purity(GoalInfo0),
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NewPurity = worst_purity(OldPurity, FollowPurity),
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goal_info_set_purity(NewPurity, GoalInfo0, GoalInfo),
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Goal = hlds_goal(GoalExpr, GoalInfo).
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_move_goals_cases(list(case)::in, list(hlds_goal)::in,
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purity::in, list(case)::out) is semidet.
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move_follow_code_move_goals_cases([], _FollowGoals, _FollowPurity, []).
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move_follow_code_move_goals_cases([Case0 | Cases0], FollowGoals, FollowPurity,
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[Case | Cases]) :-
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Case0 = case(MainConsId, OtherConsIds, Goal0),
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follow_code_conjoin_goal_and_goal_list(Goal0, FollowGoals, FollowPurity,
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Goal),
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Case = case(MainConsId, OtherConsIds, Goal),
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move_follow_code_move_goals_cases(Cases0, FollowGoals, FollowPurity,
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Cases).
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_move_goals_disj(list(hlds_goal)::in,
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list(hlds_goal)::in, purity::in, list(hlds_goal)::out) is semidet.
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move_follow_code_move_goals_disj([], _FollowGoals, _FollowPurity, []).
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move_follow_code_move_goals_disj([Goal0 | Goals0], FollowGoals, FollowPurity,
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[Goal | Goals]) :-
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follow_code_conjoin_goal_and_goal_list(Goal0, FollowGoals, FollowPurity,
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Goal),
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move_follow_code_move_goals_disj(Goals0, FollowGoals, FollowPurity, Goals).
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%-----------------------------------------------------------------------------%
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% Takes a goal and a list of goals, and conjoins them (with a potentially
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% blank goal_info), checking that the determinism of the goal is not
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% changed.
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%
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:- pred follow_code_conjoin_goal_and_goal_list(hlds_goal::in,
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list(hlds_goal)::in, purity::in, hlds_goal::out) is semidet.
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follow_code_conjoin_goal_and_goal_list(Goal0, FollowGoals, FollowPurity,
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Goal) :-
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Goal0 = hlds_goal(GoalExpr0, GoalInfo0),
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Detism0 = goal_info_get_determinism(GoalInfo0),
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determinism_components(Detism0, _CanFail0, MaxSolns0),
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(
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MaxSolns0 = at_most_zero,
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Goal = Goal0
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;
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( MaxSolns0 = at_most_one
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; MaxSolns0 = at_most_many
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; MaxSolns0 = at_most_many_cc
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),
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check_follow_code_detism(FollowGoals, Detism0),
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( if GoalExpr0 = conj(plain_conj, Conjuncts0) then
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GoalExpr = conj(plain_conj, Conjuncts0 ++ FollowGoals)
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else
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GoalExpr = conj(plain_conj, [Goal0 | FollowGoals])
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),
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OldPurity = goal_info_get_purity(GoalInfo0),
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NewPurity = worst_purity(OldPurity, FollowPurity),
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goal_info_set_purity(NewPurity, GoalInfo0, GoalInfo),
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Goal = hlds_goal(GoalExpr, GoalInfo)
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).
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% This check is necessary to make sure that follow_code doesn't change
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% the determinism of the goal.
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%
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:- pred check_follow_code_detism(list(hlds_goal)::in, determinism::in)
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is semidet.
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check_follow_code_detism([], _).
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check_follow_code_detism([hlds_goal(_, GoalInfo) | Goals], Detism0) :-
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Detism1 = goal_info_get_determinism(GoalInfo),
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det_conjunction_detism(Detism0, Detism1, Detism0),
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check_follow_code_detism(Goals, Detism0).
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%-----------------------------------------------------------------------------%
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:- pred move_follow_code_is_builtin(hlds_goal_expr::in) is semidet.
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move_follow_code_is_builtin(GoalExpr) :-
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(
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GoalExpr = unify(_, _, _, Unification, _),
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Unification \= complicated_unify(_, _, _)
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;
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GoalExpr = plain_call(_, _, _, inline_builtin, _, _)
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).
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%-----------------------------------------------------------------------------%
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:- end_module ll_backend.follow_code.
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%-----------------------------------------------------------------------------%
|