Files
mercury/compiler/add_trail_ops.m
2023-09-02 08:40:40 +10:00

669 lines
27 KiB
Mathematica

%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 2000-2012 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: add_trail_ops.m.
% Authors: fjh, juliensf.
%
% This module is an HLDS-to-HLDS transformation that inserts code to
% handle trailing. The module implements two ways of doing this:
%
% (1) by adding calls to impure predicates defined in
% library/private_builtin.m, which in turn call macros defined in
% runtime/mercury_trail.h.
%
% (2) by inserting foreign_procs that call the macros defined in
% runtime/mercury_trail.h.
%
% There is a space/time tradeoff between these two methods, the second
% is generally faster but results in larger executables.
% The `--generate-trail-ops-inline' option can be used to control which
% of the methods is used.
%
% This pass is currently only used for the MLDS back-end.
% For some reason (perhaps efficiency?? or more likely just historical?),
% the LLDS back-end inserts the trail operations as it is generating
% LLDS code, rather than via an HLDS to HLDS transformation.
%
% See compiler/notes/trailing.html for more information about trailing
% in the Mercury implementation.
%
% This module also implements trail usage optimization for those backends
% that use it to implement trailing (see trailing_analysis.m for details).
%
% NOTE: it is important that passes following this one do not attempt
% to reorder disjunctions. If trail usage optimization is being
% performed and a disjunction is reordered then the trail might
% be corrupted.
%
% TODO:
% - explore the space/time tradeoff between the inlining and
% non-inlining methods of implementing trailing.
%
%-----------------------------------------------------------------------------%
%
% XXX check goal_infos for correctness
%
%-----------------------------------------------------------------------------%
:- module ml_backend.add_trail_ops.
:- interface.
:- import_module hlds.
:- import_module hlds.hlds_module.
:- import_module hlds.hlds_pred.
:- import_module libs.
:- import_module libs.optimization_options.
:- import_module bool.
%-----------------------------------------------------------------------------%
:- pred add_trail_ops(bool::in, maybe_gen_trail_ops_inline::in,
module_info::in, proc_info::in, proc_info::out) is det.
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module hlds.code_model.
:- import_module hlds.goal_form.
:- import_module hlds.goal_util.
:- import_module hlds.hlds_goal.
:- import_module hlds.instmap.
:- import_module hlds.make_goal.
:- import_module hlds.pred_table.
:- import_module hlds.quantification.
:- import_module libs.globals.
:- import_module mdbcomp.
:- import_module mdbcomp.builtin_modules.
:- import_module mdbcomp.prim_data.
:- import_module parse_tree.
:- import_module parse_tree.builtin_lib_types.
:- import_module parse_tree.prog_data.
:- import_module parse_tree.prog_data_foreign.
:- import_module parse_tree.prog_mode.
:- import_module parse_tree.prog_type.
:- import_module parse_tree.var_table.
:- import_module list.
:- import_module maybe.
:- import_module require.
:- import_module term.
%-----------------------------------------------------------------------------%
% As we traverse the goal, we add new variables to hold the trail tickets
% (i.e. saved values of the trail pointer) and the saved values of the
% trail ticket counter. So we need to thread a var_table through,
% to record the names and types of the new variables.
%
% We also keep the module_info around, so that we can use the predicate
% table that it contains to lookup the pred_ids for the builtin procedures
% that we insert calls to. We do not update the module_info as we're
% traversing the goal.
%
:- type trail_ops_info
---> trail_ops_info(
trail_module_info :: module_info,
opt_trail_usage :: bool,
inline_ops :: maybe_gen_trail_ops_inline,
trail_var_table :: var_table
).
add_trail_ops(OptTrailUsage, GenerateInline, ModuleInfo0, !ProcInfo) :-
proc_info_get_goal(!.ProcInfo, Goal0),
proc_info_get_var_table(!.ProcInfo, VarTable0),
TrailOpsInfo0 = trail_ops_info(ModuleInfo0, OptTrailUsage, GenerateInline,
VarTable0),
goal_add_trail_ops(Goal0, Goal, TrailOpsInfo0, TrailOpsInfo),
TrailOpsInfo = trail_ops_info(_, _, _, VarTable),
proc_info_set_goal(Goal, !ProcInfo),
proc_info_set_var_table(VarTable, !ProcInfo),
% The code below does not maintain the non-local variables,
% so we need to requantify.
% XXX it would be more efficient to maintain them rather than
% recomputing them every time.
requantify_proc_general(ord_nl_no_lambda, !ProcInfo).
:- pred goal_add_trail_ops(hlds_goal::in, hlds_goal::out,
trail_ops_info::in, trail_ops_info::out) is det.
goal_add_trail_ops(Goal0, Goal, !Info) :-
Goal0 = hlds_goal(GoalExpr0, GoalInfo),
goal_expr_add_trail_ops(GoalExpr0, GoalInfo, Goal, !Info).
:- pred goal_expr_add_trail_ops(hlds_goal_expr::in, hlds_goal_info::in,
hlds_goal::out, trail_ops_info::in, trail_ops_info::out) is det.
goal_expr_add_trail_ops(GoalExpr0, GoalInfo0, Goal, !Info) :-
(
GoalExpr0 = conj(ConjType, Goals0),
conj_add_trail_ops(Goals0, Goals, !Info),
GoalExpr = conj(ConjType, Goals),
Goal = hlds_goal(GoalExpr, GoalInfo0)
;
GoalExpr0 = disj(Disjuncts0),
(
Disjuncts0 = [],
GoalExpr = GoalExpr0
;
Disjuncts0 = [_ | _],
Context = goal_info_get_context(GoalInfo0),
CodeModel = goal_info_get_code_model(GoalInfo0),
% Allocate a new trail ticket so that we can restore things on
% back-tracking.
new_ticket_var(TicketVar, !Info),
gen_store_ticket(TicketVar, Context, StoreTicketGoal, !.Info),
disj_add_trail_ops(Disjuncts0, Disjuncts, is_first_disjunct,
CodeModel, TicketVar, !Info),
GoalExpr = conj(plain_conj,
[StoreTicketGoal, hlds_goal(disj(Disjuncts), GoalInfo0)])
),
Goal = hlds_goal(GoalExpr, GoalInfo0)
;
GoalExpr0 = switch(Var, CanFail, Cases0),
cases_add_trail_ops(Cases0, Cases, !Info),
GoalExpr = switch(Var, CanFail, Cases),
Goal = hlds_goal(GoalExpr, GoalInfo0)
;
GoalExpr0 = negation(InnerGoal),
OuterGoalInfo = GoalInfo0,
% We handle negations by converting them into if-then-elses:
% not(G) ===> (if G then fail else true)
Context = goal_info_get_context(OuterGoalInfo),
InnerGoal = hlds_goal(_, InnerGoalInfo),
Determinism = goal_info_get_determinism(InnerGoalInfo),
determinism_components(Determinism, _CanFail, NumSolns),
True = true_goal_with_context(Context),
Fail = fail_goal_with_context(Context),
(
NumSolns = at_most_zero,
% The "then" part of the if-then-else will be unreachable, but to
% preserve the invariants that the MLDS back-end relies on, we
% need to make sure that it can't fail. So we use a call to
% `private_builtin.unused' (which will call error/1) rather than
% `fail' for the "then" part.
trail_generate_call(!.Info, "unused", [],
instmap_delta_bind_no_var, detism_det, purity_pure, Context,
ThenGoal)
;
( NumSolns = at_most_one
; NumSolns = at_most_many
; NumSolns = at_most_many_cc
),
ThenGoal = Fail
),
NewOuterGoal = if_then_else([], InnerGoal, ThenGoal, True),
goal_expr_add_trail_ops(NewOuterGoal, OuterGoalInfo, Goal, !Info)
;
GoalExpr0 = scope(Reason, InnerGoal0),
OuterGoalInfo = GoalInfo0,
InnerGoal0 = hlds_goal(_, InnerGoalInfo),
InnerCodeModel = goal_info_get_code_model(InnerGoalInfo),
OuterCodeModel = goal_info_get_code_model(OuterGoalInfo),
( if
InnerCodeModel = model_non,
OuterCodeModel \= model_non
then
% Handle commits.
% Before executing the goal, we save the ticket counter,
% and allocate a new trail ticket.
Context = goal_info_get_context(OuterGoalInfo),
new_ticket_counter_var(SavedTicketCounterVar, !Info),
new_ticket_var(TicketVar, !Info),
gen_mark_ticket_stack(SavedTicketCounterVar, Context,
MarkTicketStackGoal, !.Info),
gen_store_ticket(TicketVar, Context, StoreTicketGoal, !.Info),
% Next we execute the goal that we're committing across.
goal_add_trail_ops(InnerGoal0, InnerGoal, !Info),
% If the goal succeeds, then we have committed to that goal,
% so we need to commit the trail entries and prune any trail
% tickets that have been allocated since we saved the ticket
% counter.
gen_reset_ticket_commit(TicketVar, Context,
ResetTicketCommitGoal, !.Info),
gen_prune_tickets_to(SavedTicketCounterVar, Context,
PruneTicketsToGoal, !.Info),
% If the goal fails, then we should undo the trail entries and
% discard this trail ticket before backtracking over it.
gen_reset_ticket_undo(TicketVar, Context, ResetTicketUndoGoal,
!.Info),
gen_discard_ticket(Context, DiscardTicketGoal, !.Info),
FailGoal = fail_goal_with_context(Context),
% Put it all together.
Goal2 = hlds_goal(scope(Reason, InnerGoal), OuterGoalInfo),
SuccCode = hlds_goal(
conj(plain_conj,
[Goal2, ResetTicketCommitGoal, PruneTicketsToGoal]),
OuterGoalInfo),
(
OuterCodeModel = model_semi,
FailGoal = hlds_goal(_, FailGoalInfo),
FailCode = hlds_goal(
conj(plain_conj,
[ResetTicketUndoGoal, DiscardTicketGoal, FailGoal]),
FailGoalInfo),
Goal3 = hlds_goal(disj([SuccCode, FailCode]), OuterGoalInfo)
;
( OuterCodeModel = model_det
; OuterCodeModel = model_non
),
Goal3 = SuccCode
),
GoalExpr =
conj(plain_conj, [MarkTicketStackGoal, StoreTicketGoal, Goal3])
else if
Reason = from_ground_term(_, FGT),
( FGT = from_ground_term_construct
; FGT = from_ground_term_deconstruct
)
then
% The scope has no goals that either create choice points
% or allocate dynamic terms.
GoalExpr = scope(Reason, InnerGoal0)
else
goal_add_trail_ops(InnerGoal0, InnerGoal, !Info),
GoalExpr = scope(Reason, InnerGoal)
),
Goal = hlds_goal(GoalExpr, OuterGoalInfo)
;
GoalExpr0 = if_then_else(ExistQVars, Cond0, Then0, Else0),
goal_add_trail_ops(Cond0, Cond, !Info),
goal_add_trail_ops(Then0, Then1, !Info),
goal_add_trail_ops(Else0, Else1, !Info),
% If the condition does not modify the trail and does not create
% any choicepoints, then we can omit the trailing code around it.
OptTrailUsage = !.Info ^ opt_trail_usage,
Cond = hlds_goal(_, CondGoalInfo),
CondCodeModel = goal_info_get_code_model(CondGoalInfo),
( if
OptTrailUsage = yes,
CondCodeModel \= model_non,
goal_cannot_modify_trail(CondGoalInfo) = yes
then
GoalExpr = if_then_else(ExistQVars, Cond, Then1, Else1)
else
% Allocate a new trail ticket so that we can restore things if the
% condition fails.
new_ticket_var(TicketVar, !Info),
Context = goal_info_get_context(GoalInfo0),
gen_store_ticket(TicketVar, Context, StoreTicketGoal, !.Info),
% Commit the trail ticket entries if the condition succeeds.
Then1 = hlds_goal(_, Then1GoalInfo),
(
CondCodeModel = model_non,
gen_reset_ticket_solve(TicketVar, Context,
ResetTicketSolveGoal, !.Info),
Then = hlds_goal(
conj(plain_conj, [ResetTicketSolveGoal, Then1]),
Then1GoalInfo)
;
( CondCodeModel = model_det
; CondCodeModel = model_semi
),
gen_reset_ticket_commit(TicketVar, Context,
ResetTicketCommitGoal, !.Info),
gen_prune_ticket(Context, PruneTicketGoal, !.Info),
Then = hlds_goal(
conj(plain_conj,
[ResetTicketCommitGoal, PruneTicketGoal, Then1]),
Then1GoalInfo)
),
gen_reset_ticket_undo(TicketVar, Context, ResetTicketUndoGoal,
!.Info),
gen_discard_ticket(Context, DiscardTicketGoal, !.Info),
Else1 = hlds_goal(_, Else1GoalInfo),
Else = hlds_goal(
conj(plain_conj,
[ResetTicketUndoGoal, DiscardTicketGoal, Else1]),
Else1GoalInfo),
IfThenElse = hlds_goal(
if_then_else(ExistQVars, Cond, Then, Else),
GoalInfo0),
GoalExpr = conj(plain_conj, [StoreTicketGoal, IfThenElse])
),
Goal = hlds_goal(GoalExpr, GoalInfo0)
;
( GoalExpr0 = plain_call(_, _, _, _, _, _)
; GoalExpr0 = generic_call(_, _, _, _, _)
; GoalExpr0 = unify(_, _, _, _, _)
),
Goal = hlds_goal(GoalExpr0, GoalInfo0)
;
GoalExpr0 = call_foreign_proc(_, _, _, _, _, _, _),
Goal = hlds_goal(GoalExpr0, GoalInfo0)
;
GoalExpr0 = shorthand(_),
% These should have been expanded out by now.
unexpected($pred, "shorthand")
).
:- pred conj_add_trail_ops(list(hlds_goal)::in, list(hlds_goal)::out,
trail_ops_info::in, trail_ops_info::out) is det.
conj_add_trail_ops(Goals0, Goals, !Info) :-
list.map_foldl(goal_add_trail_ops, Goals0, Goals, !Info).
:- pred disj_add_trail_ops(list(hlds_goal)::in, list(hlds_goal)::out,
is_first_disjunct::in, code_model::in, prog_var::in,
trail_ops_info::in, trail_ops_info::out) is det.
disj_add_trail_ops([], [], _, _, _, !Info).
disj_add_trail_ops([Goal0 | Goals0], [Goal | Goals], IsFirstBranch, CodeModel,
TicketVar, !Info) :-
Goal0 = hlds_goal(_, GoalInfo0),
Context = goal_info_get_context(GoalInfo0),
% First undo the effects of any earlier branches.
(
IsFirstBranch = is_first_disjunct,
UndoList = []
;
IsFirstBranch = is_not_first_disjunct,
gen_reset_ticket_undo(TicketVar, Context, ResetTicketUndoGoal, !.Info),
UndoList0 = [ResetTicketUndoGoal],
(
Goals0 = [],
% Once we've reached the last disjunct, we can discard
% the trail ticket.
gen_discard_ticket(Context, DiscardTicketGoal, !.Info),
UndoList = UndoList0 ++ [DiscardTicketGoal]
;
Goals0 = [_ | _],
UndoList = UndoList0
)
),
goal_add_trail_ops(Goal0, Goal1, !Info),
% For model_semi and model_det disjunctions, once we reach the end of
% the disjunct goal, we're committing to this disjunct, so we need to
% prune the trail ticket.
(
CodeModel = model_non,
PruneList = []
;
( CodeModel = model_det
; CodeModel = model_semi
),
gen_reset_ticket_commit(TicketVar, Context, ResetTicketCommitGoal,
!.Info),
gen_prune_ticket(Context, PruneTicketGoal, !.Info),
PruneList = [ResetTicketCommitGoal, PruneTicketGoal]
),
% Package up the stuff we built earlier.
Goal1 = hlds_goal(_, GoalInfo1),
conj_list_to_goal(UndoList ++ [Goal1] ++ PruneList, GoalInfo1, Goal),
% Recursively handle the remaining disjuncts.
disj_add_trail_ops(Goals0, Goals, is_not_first_disjunct, CodeModel,
TicketVar, !Info).
:- pred cases_add_trail_ops(list(case)::in, list(case)::out,
trail_ops_info::in, trail_ops_info::out) is det.
cases_add_trail_ops([], [], !Info).
cases_add_trail_ops([Case0 | Cases0], [Case | Cases], !Info) :-
Case0 = case(MainConsId, OtherConsIds, Goal0),
goal_add_trail_ops(Goal0, Goal, !Info),
Case = case(MainConsId, OtherConsIds, Goal),
cases_add_trail_ops(Cases0, Cases, !Info).
%-----------------------------------------------------------------------------%
:- pred gen_store_ticket(prog_var::in, prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_store_ticket(TicketVar, Context, SaveTicketGoal, Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "store_ticket",
[TicketVar], instmap_delta_bind_var(TicketVar),
detism_det, purity_impure, Context, SaveTicketGoal)
;
GenerateInline = gen_trail_ops_inline,
Arg1 = foreign_arg(TicketVar,
yes(foreign_arg_name_mode("Ticket", out_mode)),
ticket_type, bp_native_if_possible),
ForeignCode = "MR_store_ticket(Ticket);",
trail_generate_call_foreign_proc(Info, "store_ticket", [Arg1],
instmap_delta_bind_var(TicketVar), purity_impure, Context,
ForeignCode, SaveTicketGoal)
).
:- pred gen_reset_ticket_undo(prog_var::in, prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_reset_ticket_undo(TicketVar, Context, ResetTicketGoal, Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "reset_ticket_undo",
[TicketVar], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, ResetTicketGoal)
;
GenerateInline = gen_trail_ops_inline,
Arg1 = foreign_arg(TicketVar,
yes(foreign_arg_name_mode("Ticket", in_mode)),
ticket_type, bp_native_if_possible),
ForeignCode = "MR_reset_ticket(Ticket, MR_undo);",
trail_generate_call_foreign_proc(Info, "reset_ticket_undo", [Arg1],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, ResetTicketGoal)
).
:- pred gen_reset_ticket_solve(prog_var::in, prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_reset_ticket_solve(TicketVar, Context, ResetTicketGoal, Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "reset_ticket_solve",
[TicketVar], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, ResetTicketGoal)
;
GenerateInline = gen_trail_ops_inline,
Arg1 = foreign_arg(TicketVar,
yes(foreign_arg_name_mode("Ticket", in_mode)),
ticket_type, bp_native_if_possible),
ForeignCode = "MR_reset_ticket(Ticket, MR_solve);",
trail_generate_call_foreign_proc(Info, "reset_ticket_solve", [Arg1],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, ResetTicketGoal)
).
:- pred gen_reset_ticket_commit(prog_var::in, prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_reset_ticket_commit(TicketVar, Context, ResetTicketGoal, Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "reset_ticket_commit",
[TicketVar], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, ResetTicketGoal)
;
GenerateInline = gen_trail_ops_inline,
Arg1 = foreign_arg(TicketVar,
yes(foreign_arg_name_mode("Ticket", in_mode)),
ticket_type, bp_native_if_possible),
ForeignCode = "MR_reset_ticket(Ticket, MR_commit);",
trail_generate_call_foreign_proc(Info, "reset_ticket_commit", [Arg1],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, ResetTicketGoal)
).
:- pred gen_prune_ticket(prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_prune_ticket(Context, PruneTicketGoal, Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "prune_ticket",
[], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, PruneTicketGoal)
;
GenerateInline = gen_trail_ops_inline,
ForeignCode = "MR_prune_ticket();",
trail_generate_call_foreign_proc(Info, "prune_ticket", [],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, PruneTicketGoal)
).
:- pred gen_discard_ticket(prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_discard_ticket(Context, DiscardTicketGoal, Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "discard_ticket",
[], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, DiscardTicketGoal)
;
GenerateInline = gen_trail_ops_inline,
ForeignCode = "MR_discard_ticket();",
trail_generate_call_foreign_proc(Info, "discard_ticket", [],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, DiscardTicketGoal)
).
:- pred gen_mark_ticket_stack(prog_var::in, prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_mark_ticket_stack(SavedTicketCounterVar, Context, MarkTicketStackGoal,
Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "mark_ticket_stack",
[SavedTicketCounterVar], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, MarkTicketStackGoal)
;
GenerateInline = gen_trail_ops_inline,
Arg1 = foreign_arg(SavedTicketCounterVar,
yes(foreign_arg_name_mode("TicketCounter", out_mode)),
ticket_counter_type, bp_native_if_possible),
ForeignCode = "MR_mark_ticket_stack(TicketCounter);",
trail_generate_call_foreign_proc(Info, "mark_ticket_stack", [Arg1],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, MarkTicketStackGoal)
).
:- pred gen_prune_tickets_to(prog_var::in, prog_context::in, hlds_goal::out,
trail_ops_info::in) is det.
gen_prune_tickets_to(SavedTicketCounterVar, Context, PruneTicketsToGoal,
Info) :-
GenerateInline = Info ^ inline_ops,
(
GenerateInline = do_not_gen_trail_ops_inline,
trail_generate_call(Info, "prune_tickets_to",
[SavedTicketCounterVar], instmap_delta_bind_no_var,
detism_det, purity_impure, Context, PruneTicketsToGoal)
;
GenerateInline = gen_trail_ops_inline,
Arg1 = foreign_arg(SavedTicketCounterVar,
yes(foreign_arg_name_mode("TicketCounter", in_mode)),
ticket_counter_type, bp_native_if_possible),
ForeignCode = "MR_prune_tickets_to(TicketCounter);",
trail_generate_call_foreign_proc(Info, "prune_tickets_to", [Arg1],
instmap_delta_bind_no_var, purity_impure, Context,
ForeignCode, PruneTicketsToGoal)
).
%-----------------------------------------------------------------------------%
:- pred new_ticket_var(prog_var::out,
trail_ops_info::in, trail_ops_info::out) is det.
new_ticket_var(Var, !Info) :-
new_var("TrailTicket", ticket_type, is_not_dummy_type, Var, !Info).
:- pred new_ticket_counter_var(prog_var::out,
trail_ops_info::in, trail_ops_info::out) is det.
new_ticket_counter_var(Var, !Info) :-
new_var("SavedTicketCounter", ticket_counter_type, is_not_dummy_type,
Var, !Info).
:- pred new_var(string::in, mer_type::in, is_dummy_type::in, prog_var::out,
trail_ops_info::in, trail_ops_info::out) is det.
new_var(Name, Type, IsDummy, Var, !Info) :-
VarTable0 = !.Info ^ trail_var_table,
Entry = vte(Name, Type, IsDummy),
add_var_entry(Entry, Var, VarTable0, VarTable),
!Info ^ trail_var_table := VarTable.
%-----------------------------------------------------------------------------%
:- func ticket_type = mer_type.
ticket_type = c_pointer_type.
:- func ticket_counter_type = mer_type.
ticket_counter_type = c_pointer_type.
%-----------------------------------------------------------------------------%
:- pred trail_generate_call(trail_ops_info::in, string::in, list(prog_var)::in,
instmap_delta::in, determinism::in, purity::in, term.context::in,
hlds_goal::out) is det.
trail_generate_call(Info, PredName, ArgVars, InstMapDelta, Detism,
Purity, Context, CallGoal) :-
ModuleInfo = Info ^ trail_module_info,
generate_plain_call(ModuleInfo, pf_predicate,
mercury_private_builtin_module, PredName, [], ArgVars, InstMapDelta,
only_mode, Detism, Purity, [], Context, CallGoal).
%-----------------------------------------------------------------------------%
:- pred trail_generate_call_foreign_proc(trail_ops_info::in, string::in,
list(foreign_arg)::in, instmap_delta::in, purity::in, term.context::in,
string::in, hlds_goal::out) is det.
trail_generate_call_foreign_proc(Info, PredName, Args, InstMapDelta,
Purity, Context, ForeignCode, ForeignProcGoal) :-
ModuleInfo = Info ^ trail_module_info,
PrivateBuiltinModule = mercury_private_builtin_module,
Detism = detism_det,
some [!ForeignProcAttrs] (
% XXX handle other target languages here.
!:ForeignProcAttrs = default_attributes(lang_c),
set_may_call_mercury(proc_will_not_call_mercury, !ForeignProcAttrs),
set_thread_safe(proc_thread_safe, !ForeignProcAttrs),
FinalForeignProcAttrs = !.ForeignProcAttrs
),
ExtraArgs = [],
MaybeTraceRuntimeCond = no,
generate_call_foreign_proc(ModuleInfo, pf_predicate,
PrivateBuiltinModule, PredName, [], Args, ExtraArgs, InstMapDelta,
only_mode, Detism, Purity, [], FinalForeignProcAttrs,
MaybeTraceRuntimeCond, ForeignCode, Context, ForeignProcGoal).
%-----------------------------------------------------------------------------%
:- end_module ml_backend.add_trail_ops.
%-----------------------------------------------------------------------------%