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168f531867
Estimated hours taken: 4 Branches: main Add new fields to the goal_info structure for region based memory management. The fields are currently unused, but (a) Quan will add the code to fill them in, and then (b) I will modify the code generator to use the filled in fields. compiler/hlds_goal.m: Make the change described above. Group all the procedures that access goal_info components together. Some of the getters were predicates while some were functions, so this diff changes them all to be functions. (The setters remain predicates.) compiler/*.m: Trivial changes to conform to the change in hlds_goal.m. In simplify.m, break up a huge (800+ line) predicate into smaller pieces.
247 lines
10 KiB
Mathematica
247 lines
10 KiB
Mathematica
%-----------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%-----------------------------------------------------------------------------%
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% Copyright (C) 2006-2007 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: structure_reuse.direct.detect_garbage.m.
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% Main authors: nancy.
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%
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% Detect where datastructures become garbage in a given procedure: construct
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% a dead cell table.
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%
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%-----------------------------------------------------------------------------%
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:- module transform_hlds.ctgc.structure_reuse.direct.detect_garbage.
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:- interface.
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% Using the sharing table listing all the structure sharing of all
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% the known procedures, return a table of all data structures that may
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% become available for reuse (i.e. cells that may become dead) of a given
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% procedure goal. The table also records the reuse condition associated
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% with each of the dead cells.
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%
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:- pred determine_dead_deconstructions(module_info::in, pred_info::in,
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proc_info::in, sharing_as_table::in, hlds_goal::in,
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dead_cell_table::out) is det.
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- implementation.
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:- import_module libs.compiler_util.
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:- import_module parse_tree.prog_data.
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:- import_module transform_hlds.ctgc.datastruct.
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:- import_module pair.
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:- import_module set.
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:- import_module string.
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%-----------------------------------------------------------------------------%
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:- type detect_bg_info
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---> detect_bg_info(
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module_info :: module_info,
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pred_info :: pred_info,
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proc_info :: proc_info,
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sharing_table :: sharing_as_table
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).
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:- func detect_bg_info_init(module_info, pred_info, proc_info,
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sharing_as_table) = detect_bg_info.
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detect_bg_info_init(ModuleInfo, PredInfo, ProcInfo, SharingTable) =
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detect_bg_info(ModuleInfo, PredInfo, ProcInfo, SharingTable).
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determine_dead_deconstructions(ModuleInfo, PredInfo, ProcInfo, SharingTable,
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Goal, DeadCellTable) :-
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determine_dead_deconstructions(
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detect_bg_info_init(ModuleInfo, PredInfo, ProcInfo, SharingTable),
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Goal, DeadCellTable).
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:- pred determine_dead_deconstructions(detect_bg_info::in, hlds_goal::in,
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dead_cell_table::out) is det.
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determine_dead_deconstructions(Background, Goal, DeadCellTable):-
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% In this process we need to know the sharing at each program point,
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% which boils down to reconstructing that sharing information based on the
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% sharing recorded in the sharing table.
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determine_dead_deconstructions_2(Background, Goal,
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sharing_as_init, _, dead_cell_table_init, DeadCellTable).
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% Process a procedure goal, determining the sharing at each subgoal, as
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% well as constructing the table of dead cells.
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%
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% This means:
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% - at each program point: compute sharing
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% - at deconstruction unifications: check for a dead cell.
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%
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:- pred determine_dead_deconstructions_2(detect_bg_info::in, hlds_goal::in,
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sharing_as::in, sharing_as::out, dead_cell_table::in,
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dead_cell_table::out) is det.
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determine_dead_deconstructions_2(Background, TopGoal, !SharingAs,
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!DeadCellTable) :-
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TopGoal = hlds_goal(GoalExpr, GoalInfo),
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ModuleInfo = Background ^ module_info,
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PredInfo = Background ^ pred_info,
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ProcInfo = Background ^ proc_info,
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SharingTable = Background ^ sharing_table,
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(
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GoalExpr = conj(_, Goals),
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list.foldl2(determine_dead_deconstructions_2(Background),
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Goals, !SharingAs, !DeadCellTable)
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;
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GoalExpr = plain_call(PredId, ProcId, ActualVars, _, _, _),
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lookup_sharing_and_comb(ModuleInfo, PredInfo, ProcInfo, SharingTable,
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PredId, ProcId, ActualVars, !SharingAs)
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;
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GoalExpr = generic_call(_GenDetails, _, _, _),
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Context = goal_info_get_context(GoalInfo),
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context_to_string(Context, ContextString),
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!:SharingAs = sharing_as_top_sharing_accumulate(
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"generic call (" ++ ContextString ++ ")", !.SharingAs)
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;
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GoalExpr = unify(_, _, _, Unification, _),
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unification_verify_reuse(ModuleInfo, ProcInfo, GoalInfo,
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Unification, program_point_init(GoalInfo), !.SharingAs,
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!DeadCellTable),
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!:SharingAs = add_unify_sharing(ModuleInfo, ProcInfo, Unification,
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GoalInfo, !.SharingAs)
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;
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GoalExpr = disj(Goals),
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determine_dead_deconstructions_2_disj(Background, Goals, !SharingAs,
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!DeadCellTable)
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;
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GoalExpr = switch(_, _, Cases),
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determine_dead_deconstructions_2_disj(Background,
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list.map(func(C) = G :- (G = C ^ case_goal), Cases), !SharingAs,
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!DeadCellTable)
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;
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% XXX To check and compare with the theory.
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GoalExpr = negation(_Goal)
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;
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GoalExpr = scope(_, SubGoal),
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determine_dead_deconstructions_2(Background, SubGoal, !SharingAs,
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!DeadCellTable)
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;
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GoalExpr = if_then_else(_, IfGoal, ThenGoal, ElseGoal),
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determine_dead_deconstructions_2(Background, IfGoal, !.SharingAs,
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IfSharingAs, !DeadCellTable),
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determine_dead_deconstructions_2(Background, ThenGoal, IfSharingAs,
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ThenSharingAs, !DeadCellTable),
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determine_dead_deconstructions_2(Background, ElseGoal, !.SharingAs,
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ElseSharingAs, !DeadCellTable),
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!:SharingAs = sharing_as_least_upper_bound(ModuleInfo, ProcInfo,
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ThenSharingAs, ElseSharingAs)
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;
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GoalExpr = call_foreign_proc(Attributes, ForeignPredId, ForeignProcId,
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_Args, _ExtraArgs, _MaybeTraceRuntimeCond, _Impl),
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Context = goal_info_get_context(GoalInfo),
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!:SharingAs = add_foreign_proc_sharing(ModuleInfo, ProcInfo,
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proc(ForeignPredId, ForeignProcId), Attributes, Context,
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!.SharingAs)
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;
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GoalExpr = shorthand(_),
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unexpected(detect_garbage.this_file,
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"determine_dead_deconstructions_2: shorthand goal.")
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).
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:- pred determine_dead_deconstructions_2_disj(detect_bg_info::in,
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hlds_goals::in, sharing_as::in, sharing_as::out,
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dead_cell_table::in, dead_cell_table::out) is det.
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determine_dead_deconstructions_2_disj(Background, Goals,
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!SharingAs, !DeadCellTable) :-
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list.foldl2(determine_dead_deconstructions_2_disj_goal(Background,
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!.SharingAs), Goals, !SharingAs, !DeadCellTable).
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:- pred determine_dead_deconstructions_2_disj_goal(detect_bg_info::in,
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sharing_as::in, hlds_goal::in, sharing_as::in, sharing_as::out,
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dead_cell_table::in, dead_cell_table::out) is det.
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determine_dead_deconstructions_2_disj_goal(Background, SharingBeforeDisj,
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Goal, !SharingAs, !DeadCellTable) :-
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determine_dead_deconstructions_2(Background, Goal, SharingBeforeDisj,
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GoalSharing, !DeadCellTable),
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!:SharingAs = sharing_as_least_upper_bound(Background ^ module_info,
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Background ^ proc_info, !.SharingAs, GoalSharing).
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% Verify whether the unification is a deconstruction in which the
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% deconstructed data structure becomes garbage (under some reuse
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% conditions).
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%
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% XXX Different implementation from the reuse-branch implementation.
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%
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:- pred unification_verify_reuse(module_info::in, proc_info::in,
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hlds_goal_info::in, unification::in, program_point::in,
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sharing_as::in, dead_cell_table::in, dead_cell_table::out) is det.
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unification_verify_reuse(ModuleInfo, ProcInfo, GoalInfo, Unification,
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PP, Sharing, !DeadCellTable):-
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(
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Unification = deconstruct(Var, ConsId, _, _, _, _),
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LFU = goal_info_get_lfu(GoalInfo),
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LBU = goal_info_get_lbu(GoalInfo),
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(
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% Reuse is only relevant for real constructors, with
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% arity different from 0.
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ConsId = cons(_, Arity),
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Arity \= 0,
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% Check if the top cell datastructure of Var is not live.
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% If Sharing is top, then everything should automatically
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% be considered live, hence no reuse possible.
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\+ sharing_as_is_top(Sharing),
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% Check the live set of data structures at this program point.
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set.union(LFU, LBU, LU),
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LU_data = set.to_sorted_list(set.map(datastruct_init, LU)),
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LiveData = list.condense(
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list.map(
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extend_datastruct(ModuleInfo, ProcInfo, Sharing),
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LU_data)),
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\+ var_is_live(Var, LiveData)
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->
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% If all the above conditions are met, then the top
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% cell data structure based on Var is dead right after
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% this deconstruction, hence, may be involved with
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% structure reuse.
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NewCondition = reuse_condition_init(ModuleInfo,
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ProcInfo, Var, LFU, LBU, Sharing),
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dead_cell_table_set(PP, NewCondition, !DeadCellTable)
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;
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true
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)
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;
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Unification = construct(_, _, _, _, _, _, _)
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;
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Unification = assign(_, _)
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;
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Unification = simple_test(_, _)
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;
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Unification = complicated_unify(_, _, _),
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unexpected(detect_garbage.this_file, "unification_verify_reuse: " ++
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"complicated_unify/3 encountered.")
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).
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:- pred var_is_live(prog_var::in, list(datastruct)::in) is semidet.
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var_is_live(Var, LiveData) :-
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list.member(datastruct_init(Var), LiveData).
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%-----------------------------------------------------------------------------%
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:- func this_file = string.
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this_file = "structure_sharing.direct.detect_garbage.m".
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%-----------------------------------------------------------------------------%
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:- end_module transform_hlds.ctgc.structure_reuse.direct.detect_garbage.
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%-----------------------------------------------------------------------------%
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