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mercury/compiler/modecheck_unify.m
Zoltan Somogyi a9a2825ace Replace __ with . as the module qualifier everywhere in all the modules 
Estimated hours taken: 0.5
Branches: main

profiler/*.m:
deep_profiler/*.m:
compiler/*.m:
	Replace __ with . as the module qualifier everywhere in all the modules
	of the profiler and deep profiler and in some modules of the compiler.
2006-03-09 04:56:47 +00:00

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%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 1996-2006 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: modecheck_unify.m.
% Main author: fjh.
% This module contains the code to modecheck a unification.
%
% Check that the unification doesn't attempt to unify two free variables
% (or in general two free sub-terms) unless one of them is dead. (Also we
% ought to split unifications up if necessary to avoid complicated
% sub-unifications.)
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- module check_hlds.modecheck_unify.
:- interface.
:- import_module check_hlds.mode_info.
:- import_module hlds.hlds_goal.
:- import_module parse_tree.prog_data.
:- import_module io.
% Modecheck a unification.
%
:- pred modecheck_unification(prog_var::in, unify_rhs::in, unification::in,
unify_context::in, hlds_goal_info::in, hlds_goal_expr::out,
mode_info::in, mode_info::out, io::di, io::uo) is det.
% Create a unification between the two given variables.
% The goal's mode and determinism information are not filled in.
%
:- pred create_var_var_unification(prog_var::in, prog_var::in,
mer_type::in, mode_info::in, hlds_goal::out) is det.
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module check_hlds.inst_match.
:- import_module check_hlds.inst_util.
:- import_module check_hlds.modecheck_call.
:- import_module check_hlds.mode_debug.
:- import_module check_hlds.mode_errors.
:- import_module check_hlds.mode_info.
:- import_module check_hlds.modes.
:- import_module check_hlds.mode_util.
:- import_module check_hlds.polymorphism.
:- import_module check_hlds.typecheck.
:- import_module check_hlds.type_util.
:- import_module check_hlds.unify_proc.
:- import_module check_hlds.unique_modes.
:- import_module hlds.hlds_data.
:- import_module hlds.hlds_goal.
:- import_module hlds.hlds_module.
:- import_module hlds.hlds_out.
:- import_module hlds.hlds_pred.
:- import_module hlds.instmap.
:- import_module hlds.make_hlds.
:- import_module hlds.quantification.
:- import_module libs.compiler_util.
:- import_module libs.globals.
:- import_module libs.options.
:- import_module mdbcomp.prim_data.
:- import_module parse_tree.module_qual.
:- import_module parse_tree.prog_mode.
:- import_module parse_tree.prog_out.
:- import_module parse_tree.prog_type.
:- import_module parse_tree.prog_util.
:- import_module assoc_list.
:- import_module bool.
:- import_module int.
:- import_module list.
:- import_module map.
:- import_module set.
:- import_module std_util.
:- import_module string.
:- import_module term.
:- import_module varset.
%-----------------------------------------------------------------------------%
% We first have to check that if a unification occurs in a negated
% context with an inst any argument then it has an explicit `impure'
% annotation.
%
% With lambdas, the lambda itself must be marked as impure if it includes
% any inst any nonlocals (executing such a lambda may have the side effect
% of constraining a nonlocal solver variable).
%
modecheck_unification(X, RHS, Unification0, UnifyContext, UnifyGoalInfo0,
Unify, !ModeInfo, !IO) :-
(
% If this is a lambda unification containing some inst any
% nonlocals, then the lambda should be marked as impure.
%
RHS = lambda_goal(Purity, _, _, NonLocals, _, _, _, _),
Purity \= purity_impure,
mode_info_get_module_info(!.ModeInfo, ModuleInfo),
mode_info_get_instmap(!.ModeInfo, InstMap),
AnyVars = list.filter(var_inst_contains_any(ModuleInfo, InstMap),
NonLocals),
AnyVars = [_ | _]
->
set.init(WaitingVars),
mode_info_error(WaitingVars,
purity_error_lambda_should_be_impure(AnyVars), !ModeInfo),
Unify = conj(plain_conj, [])
;
modecheck_unification_2(X, RHS, Unification0, UnifyContext,
UnifyGoalInfo0, Unify, !ModeInfo, !IO)
).
:- pred modecheck_unification_2(prog_var::in, unify_rhs::in, unification::in,
unify_context::in, hlds_goal_info::in, hlds_goal_expr::out,
mode_info::in, mode_info::out, io::di, io::uo) is det.
modecheck_unification_2(X, var(Y), Unification0, UnifyContext, UnifyGoalInfo0,
Unify, !ModeInfo, !IO) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
mode_info_get_var_types(!.ModeInfo, VarTypes),
mode_info_get_instmap(!.ModeInfo, InstMap0),
instmap.lookup_var(InstMap0, X, InstOfX0),
instmap.lookup_var(InstMap0, Y, InstOfY0),
% If X and Y are free and have a solver type and we are allowed to
% insert initialisation calls at this point, then do so to allow
% scheduling of the unification.
(
mode_info_may_initialise_solver_vars(!.ModeInfo),
InstOfX0 = free,
InstOfY0 = free,
VarType = VarTypes^elem(X),
type_util.type_is_solver_type(ModuleInfo0, VarType)
->
modes.construct_initialisation_call(X, VarType, any_inst,
context_init, no, InitXGoal, !ModeInfo),
MaybeInitX = yes(InitXGoal),
instmap.set(X, any_inst, InstMap0, InstMap),
InstOfX = any_inst,
InstOfY = InstOfY0
;
MaybeInitX = no,
InstMap = InstMap0,
InstOfX = InstOfX0,
InstOfY = InstOfY0
),
mode_info_var_is_live(!.ModeInfo, X, LiveX),
mode_info_var_is_live(!.ModeInfo, Y, LiveY),
(
( LiveX = live, LiveY = live ->
BothLive = live
;
BothLive = dead
),
abstractly_unify_inst(BothLive, InstOfX, InstOfY, real_unify,
UnifyInst, Det1, ModuleInfo0, ModuleInfo1),
% Don't allow free-free unifications if both variables are locked.
% (Normally the checks for binding locked variables are done in
% modecheck_set_var_inst, which is called below, but that won't catch
% this case, because the inst of the variable will remain `free'.
% XXX are there other cases like this one?)
\+ (
UnifyInst = free,
mode_info_var_is_locked(!.ModeInfo, X, _XLockedReason),
mode_info_var_is_locked(!.ModeInfo, Y, _YLockedReason),
% a unification of the form `X = X' doesn't bind X,
% and thus should be allowed even if X is locked
X \= Y
)
->
Inst = UnifyInst,
Det = Det1,
mode_info_set_module_info(ModuleInfo1, !ModeInfo),
modecheck_set_var_inst(X, Inst, yes(InstOfY), !ModeInfo),
modecheck_set_var_inst(Y, Inst, yes(InstOfX), !ModeInfo),
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
categorize_unify_var_var(ModeOfX, ModeOfY, LiveX, LiveY, X, Y,
Det, UnifyContext, UnifyGoalInfo0, VarTypes, Unification0, Unify0,
!ModeInfo),
(
MaybeInitX = no,
Unify = Unify0
;
MaybeInitX = yes(InitGoal - InitGoalInfo),
modes.compute_goal_instmap_delta(InstMap, Unify0,
UnifyGoalInfo0, UnifyGoalInfo, !ModeInfo),
Unify = conj(plain_conj,
[InitGoal - InitGoalInfo, Unify0 - UnifyGoalInfo])
)
;
set.list_to_set([X, Y], WaitingVars),
mode_info_error(WaitingVars,
mode_error_unify_var_var(X, Y, InstOfX, InstOfY), !ModeInfo),
% If we get an error, set the inst to not_reached to suppress
% follow-on errors. But don't call categorize_unification, because
% that could cause an invalid call to `unify_proc.request_unify'
Inst = not_reached,
modecheck_set_var_inst(X, Inst, no, !ModeInfo),
modecheck_set_var_inst(Y, Inst, no, !ModeInfo),
% Return any old garbage.
Unification = assign(X, Y),
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
Modes = ModeOfX - ModeOfY,
Unify = unify(X, var(Y), Modes, Unification, UnifyContext)
).
modecheck_unification_2(X0, functor(ConsId0, IsExistConstruction, ArgVars0),
Unification0, UnifyContext, GoalInfo0, Goal, !ModeInfo, !IO) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
mode_info_get_var_types(!.ModeInfo, VarTypes0),
map.lookup(VarTypes0, X0, TypeOfX),
%
% We replace any unifications with higher-order pred constants
% by lambda expressions. For example, we replace
%
% X = list.append(Y) % Y::in, X::out
%
% with
%
% X = lambda [A1::in, A2::out] (list.append(Y, A1, A2))
%
% Normally this is done by polymorphism.process_unify_functor,
% but if we're re-modechecking goals after lambda.m has been run
% (e.g. for deforestation), then we may need to do it again here.
% Note that any changes to this code here will probably need to be
% duplicated there too.
%
(
% check if variable has a higher-order type
type_is_higher_order(TypeOfX, Purity, _, EvalMethod,
PredArgTypes),
ConsId0 = pred_const(ShroudedPredProcId, _)
->
% Convert the pred term to a lambda expression.
mode_info_get_varset(!.ModeInfo, VarSet0),
mode_info_get_context(!.ModeInfo, Context),
proc(PredId, ProcId) =
unshroud_pred_proc_id(ShroudedPredProcId),
convert_pred_to_lambda_goal(Purity, EvalMethod,
X0, PredId, ProcId, ArgVars0, PredArgTypes,
UnifyContext, GoalInfo0, Context,
ModuleInfo0, Functor0,
VarSet0, VarSet, VarTypes0, VarTypes),
mode_info_set_varset(VarSet, !ModeInfo),
mode_info_set_var_types(VarTypes, !ModeInfo),
% Modecheck this unification in its new form.
modecheck_unification_2(X0, Functor0, Unification0, UnifyContext,
GoalInfo0, Goal, !ModeInfo, !IO)
;
% It's not a higher-order pred unification - just
% call modecheck_unify_functor to do the ordinary thing.
modecheck_unify_functor(X0, TypeOfX, ConsId0,
IsExistConstruction, ArgVars0, Unification0,
UnifyContext, GoalInfo0, Goal, !ModeInfo, !IO)
).
modecheck_unification_2(X, LambdaGoal, Unification0, UnifyContext, _GoalInfo,
unify(X, RHS, Mode, Unification, UnifyContext), !ModeInfo, !IO) :-
LambdaGoal = lambda_goal(Purity, PredOrFunc, EvalMethod,
ArgVars, Vars, Modes0, Det, Goal0),
% First modecheck the lambda goal itself:
%
% initialize the initial insts of the lambda variables,
% check that the non-local vars are ground (XXX or any),
% mark the non-local vars as shared,
% lock the non-local vars,
% mark the non-clobbered lambda variables as live,
% modecheck the goal,
% check that the final insts are correct,
% unmark the live vars,
% unlock the non-local vars,
% restore the original instmap.
%
% XXX or should we merge the original and the final instmaps???
%
% The reason that we need to merge the original and final instmaps is
% as follows. The lambda goal will not have bound any variables (since
% they were locked), but it may have added some information or lost some
% uniqueness. We cannot use the final instmap, because that may have
% too much information. If we use the initial instmap, variables will be
% considered as unique even if they become shared or clobbered in the
% lambda goal!
%
% However even this may not be enough. If a unique non-local variable
% is used in its unique inst (e.g. it's used in a ui mode) and then shared
% within the lambda body, this is unsound. This variable should be marked
% as shared at the _top_ of the lambda goal. As for implementing this,
% it probably means that the lambda goal should be re-modechecked,
% or even modechecked to a fixpoint.
%
% For the moment, since doing all that properly seems too hard, we just
% share all non-local variables at the top of the lambda goal. This is
% safe, but perhaps too conservative.
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
mode_info_get_how_to_check(!.ModeInfo, HowToCheckGoal),
( HowToCheckGoal = check_modes ->
% This only needs to be done once.
mode_info_get_types_of_vars(!.ModeInfo, Vars, VarTypes),
propagate_types_into_mode_list(ModuleInfo0, VarTypes, Modes0, Modes)
;
Modes = Modes0
),
% Initialize the initial insts of the lambda variables.
mode_list_get_initial_insts(ModuleInfo0, Modes, VarInitialInsts),
assoc_list.from_corresponding_lists(Vars, VarInitialInsts, VarInstAL),
instmap_delta_from_assoc_list(VarInstAL, VarInstMapDelta),
mode_info_get_instmap(!.ModeInfo, InstMap0),
instmap.apply_instmap_delta(InstMap0, VarInstMapDelta, InstMap1),
mode_info_set_instmap(InstMap1, !ModeInfo),
% Mark the non-clobbered lambda variables as live.
get_arg_lives(ModuleInfo0, Modes, ArgLives),
get_live_vars(Vars, ArgLives, LiveVarsList),
set.list_to_set(LiveVarsList, LiveVars),
mode_info_add_live_vars(LiveVars, !ModeInfo),
% Lock the non-locals. (A lambda goal is not allowed to bind any of the
% non-local variables, since it could get called more than once, or
% from inside a negation)
Goal0 = _ - GoalInfo0,
goal_info_get_nonlocals(GoalInfo0, NonLocals0),
set.delete_list(NonLocals0, Vars, NonLocals),
set.to_sorted_list(NonLocals, NonLocalsList),
instmap.lookup_vars(NonLocalsList, InstMap1, NonLocalInsts),
mode_info_get_module_info(!.ModeInfo, ModuleInfo2),
(
% XXX This test is too conservative.
%
% We should allow non-local variables to be non-ground sometimes,
% possibly dependent on whether or not they are dead after this
% unification. In addition, we should not "share" a unique non-local
% variable if these two conditions hold:
%
% - It is dead after this unification.
% - It is not shared within the lambda body.
%
% Unfortunately, we can't test the latter condition until after
% we've mode-checked the lambda body. (See the above comment on
% merging the initial and final instmaps.)
% XXX This test is also not conservative enough!
%
% We should not allow non-local vars to have inst `any'; because that
% can lead to unsoundness. However, disallowing that idiom would break
% extras/trailed_update/samples/vqueens.m, and would make freeze/3
% basically useless... so for now at least, let's not disallow it,
% even though it is unsafe.
inst_list_is_ground_or_any(NonLocalInsts, ModuleInfo2)
->
make_shared_inst_list(NonLocalInsts, SharedNonLocalInsts,
ModuleInfo2, ModuleInfo3),
instmap.set_vars(NonLocalsList, SharedNonLocalInsts,
InstMap1, InstMap2),
mode_info_set_module_info(ModuleInfo3, !ModeInfo),
mode_info_set_instmap(InstMap2, !ModeInfo),
mode_info_lock_vars(lambda(PredOrFunc), NonLocals, !ModeInfo),
mode_checkpoint(enter, "lambda goal", !ModeInfo, !IO),
% If we're being called from unique_modes.m, then we need to
% call unique_modes.check_goal rather than modecheck_goal.
( HowToCheckGoal = check_unique_modes ->
unique_modes.check_goal(Goal0, Goal1, !ModeInfo, !IO)
;
modecheck_goal(Goal0, Goal1, !ModeInfo, !IO)
),
mode_list_get_final_insts(ModuleInfo0, Modes, FinalInsts),
modecheck_lambda_final_insts(Vars, FinalInsts, Goal1, Goal, !ModeInfo),
mode_checkpoint(exit, "lambda goal", !ModeInfo, !IO),
mode_info_remove_live_vars(LiveVars, !ModeInfo),
mode_info_unlock_vars(lambda(PredOrFunc), NonLocals, !ModeInfo),
% Ensure that the non-local vars are shared OUTSIDE the
% lambda unification as well as inside.
instmap.set_vars(NonLocalsList, SharedNonLocalInsts,
InstMap0, InstMap11),
mode_info_set_instmap(InstMap11, !ModeInfo),
% Now modecheck the unification of X with the lambda-expression.
RHS0 = lambda_goal(Purity, PredOrFunc, EvalMethod, ArgVars,
Vars, Modes, Det, Goal),
modecheck_unify_lambda(X, PredOrFunc, ArgVars, Modes, Det,
RHS0, RHS, Unification0, Unification, Mode, !ModeInfo)
;
list.filter(
(pred(Var :: in) is semidet :-
instmap.lookup_var(InstMap1, Var, Inst),
\+ inst_is_ground(ModuleInfo2, Inst)
), NonLocalsList, NonGroundNonLocals),
( NonGroundNonLocals = [BadVar | _] ->
instmap.lookup_var(InstMap1, BadVar, BadInst),
set.singleton_set(WaitingVars, BadVar),
mode_info_error(WaitingVars,
mode_error_non_local_lambda_var(BadVar, BadInst), !ModeInfo)
;
unexpected(this_file,
"modecheck_unification_2(lambda): very strange var")
),
% Return any old garbage.
RHS = lambda_goal(Purity, PredOrFunc, EvalMethod, ArgVars,
Vars, Modes0, Det, Goal0),
Mode = (free -> free) - (free -> free),
Unification = Unification0
).
:- pred modecheck_unify_lambda(prog_var::in, pred_or_func::in,
list(prog_var)::in, list(mer_mode)::in, determinism::in,
unify_rhs::in, unify_rhs::out, unification::in, unification::out,
pair(mer_mode)::out, mode_info::in, mode_info::out) is det.
modecheck_unify_lambda(X, PredOrFunc, ArgVars, LambdaModes, LambdaDet,
RHS0, RHS, Unification0, Unification, Mode, !ModeInfo) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
mode_info_get_instmap(!.ModeInfo, InstMap0),
instmap.lookup_var(InstMap0, X, InstOfX),
InstOfY = ground(unique, higher_order(LambdaPredInfo)),
LambdaPredInfo = pred_inst_info(PredOrFunc, LambdaModes, LambdaDet),
(
abstractly_unify_inst(dead, InstOfX, InstOfY, real_unify,
UnifyInst, _Det, ModuleInfo0, ModuleInfo1)
->
Inst = UnifyInst,
mode_info_set_module_info(ModuleInfo1, !ModeInfo),
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
Mode = ModeOfX - ModeOfY,
% the lambda expression just maps its argument variables
% from their current insts to the same inst
instmap.lookup_vars(ArgVars, InstMap0, ArgInsts),
inst_lists_to_mode_list(ArgInsts, ArgInsts, ArgModes),
categorize_unify_var_lambda(ModeOfX, ArgModes, X, ArgVars, PredOrFunc,
RHS0, RHS, Unification0, Unification, !ModeInfo),
modecheck_set_var_inst(X, Inst, no, !ModeInfo)
;
set.list_to_set([X], WaitingVars),
mode_info_error(WaitingVars,
mode_error_unify_var_lambda(X, InstOfX, InstOfY),
!ModeInfo),
% If we get an error, set the inst to not_reached to avoid cascading
% errors. But don't call categorize_unification, because that could
% cause an invalid call to `unify_proc.request_unify'
Inst = not_reached,
modecheck_set_var_inst(X, Inst, no, !ModeInfo),
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
Mode = ModeOfX - ModeOfY,
% Return any old garbage.
Unification = Unification0,
RHS = RHS0
).
:- pred modecheck_unify_functor(prog_var::in, mer_type::in, cons_id::in,
is_existential_construction::in, list(prog_var)::in, unification::in,
unify_context::in, hlds_goal_info::in, hlds_goal_expr::out,
mode_info::in, mode_info::out, io::di, io::uo) is det.
modecheck_unify_functor(X0, TypeOfX, ConsId0, IsExistConstruction, ArgVars0,
Unification0, UnifyContext, GoalInfo0, Goal, !ModeInfo, !IO) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
mode_info_get_how_to_check(!.ModeInfo, HowToCheckGoal),
% Fully module qualify all cons_ids (except for builtins such as
% ints and characters).
qualify_cons_id(TypeOfX, ArgVars0, ConsId0, ConsId, InstConsId),
mode_info_get_instmap(!.ModeInfo, InstMap0),
instmap.lookup_var(InstMap0, X0, InstOfX0),
(
% If the unification was originally of the form X = 'new f'(Y),
% it must be classified as a construction. If it were classified as a
% deconstruction, the argument unifications would be ill-typed.
IsExistConstruction = yes,
\+ inst_is_free(ModuleInfo0, InstOfX0)
->
% To make sure the unification is classified as a construction,
% if X is already bound, we must add a unification with an extra
% variable:
% Z = 'new f'(Y),
% X = Z.
InstOfX = free,
LiveX = live,
make_complicated_sub_unify(X0, X, ExtraGoals0, !ModeInfo)
;
InstOfX = InstOfX0,
X = X0,
mode_info_var_is_live(!.ModeInfo, X, LiveX),
ExtraGoals0 = no_extra_goals
),
% This needs to come after make_complicated_sub_unify because
% make_complicated_sub_unify may introduce new variables
% whose types we need to look-up.
%
mode_info_get_var_types(!.ModeInfo, VarTypes),
(
% If we are allowed to insert solver type initialisation calls and
% InstOfX0 is free and all ArgVars0 are either non-free or have
% solver types, then we know that this is going to be a construction,
% so we can insert the necessary initialisation calls.
ArgVars0 \= [],
HowToCheckGoal \= check_unique_modes,
inst_match.inst_is_free(ModuleInfo0, InstOfX),
mode_info_may_initialise_solver_vars(!.ModeInfo),
instmap.lookup_vars(ArgVars0, InstMap0, InstArgs0),
all_arg_vars_are_non_free_or_solver_vars(ArgVars0, InstArgs0,
VarTypes, ModuleInfo0, ArgVarsToInit)
->
modes.construct_initialisation_calls(ArgVarsToInit, InitGoals,
!ModeInfo),
(
InitGoals = [],
ExtraGoals1 = no_extra_goals
;
InitGoals = [_ | _],
ExtraGoals1 = extra_goals(InitGoals, [])
)
;
ExtraGoals1 = no_extra_goals
),
mode_info_get_instmap(!.ModeInfo, InstMap1),
instmap.lookup_vars(ArgVars0, InstMap1, InstArgs),
mode_info_var_list_is_live(!.ModeInfo, ArgVars0, LiveArgs),
InstOfY = bound(unique, [functor(InstConsId, InstArgs)]),
(
% The occur check: X = f(X) is considered a mode error unless X is
% ground. (Actually it wouldn't be that hard to generate code for it
% - it always fails! - but it's most likely to be a programming error,
% so it's better to report it.)
list.member(X, ArgVars0),
\+ inst_is_ground(ModuleInfo0, InstOfX)
->
set.list_to_set([X], WaitingVars),
mode_info_error(WaitingVars,
mode_error_unify_var_functor(X, InstConsId, ArgVars0,
InstOfX, InstArgs),
!ModeInfo),
Inst = not_reached,
Det = erroneous,
% If we get an error, set the inst to not_reached to avoid
% cascading errors. But don't call categorize_unification, because
% that could cause an invalid call to `unify_proc.request_unify'.
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
Mode = ModeOfX - ModeOfY,
modecheck_set_var_inst(X, Inst, no, !ModeInfo),
NoArgInsts = list.duplicate(length(ArgVars0), no),
bind_args(Inst, ArgVars0, NoArgInsts, !ModeInfo),
% Return any old garbage.
Unification = Unification0,
ArgVars = ArgVars0,
ExtraGoals2 = no_extra_goals
;
% XXX We forbid the construction of partially instantiated
% structures involving solver types. We'd like to forbid all
% such constructions here, but that causes trouble with the current
% implementation of term.term_to_univ_special_case which does
% use partial instantiation (in a rather horrible way). This is
% a hacky solution that gets us most of what we want w.r.t.
% solver types.
not (
inst_is_free(ModuleInfo0, InstOfX),
list.member(InstArg, InstArgs),
inst_is_free(ModuleInfo0, InstArg),
list.member(ArgVar, ArgVars0),
ArgType = VarTypes ^ elem(ArgVar),
type_is_solver_type(ModuleInfo0, ArgType)
),
abstractly_unify_inst_functor(LiveX, InstOfX, InstConsId,
InstArgs, LiveArgs, real_unify, TypeOfX,
UnifyInst, Det1, ModuleInfo0, ModuleInfo1)
->
Inst = UnifyInst,
Det = Det1,
mode_info_set_module_info(ModuleInfo1, !ModeInfo),
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
Mode = ModeOfX - ModeOfY,
( get_mode_of_args(Inst, InstArgs, ModeArgs0) ->
ModeArgs = ModeArgs0
;
unexpected(this_file, "get_mode_of_args failed")
),
(
inst_expand_and_remove_constrained_inst_vars(ModuleInfo1,
InstOfX, InstOfX1),
list.length(ArgVars0, Arity),
get_arg_insts(InstOfX1, InstConsId, Arity, InstOfXArgs0),
get_mode_of_args(Inst, InstOfXArgs0, ModeOfXArgs0)
->
ModeOfXArgs = ModeOfXArgs0,
InstOfXArgs = InstOfXArgs0
;
unexpected(this_file, "get_(inst/mode)_of_args failed")
),
categorize_unify_var_functor(ModeOfX, ModeOfXArgs, ModeArgs,
X, ConsId, ArgVars0, VarTypes, UnifyContext,
Unification0, Unification1, !ModeInfo),
split_complicated_subunifies(Unification1, Unification,
ArgVars0, ArgVars, ExtraGoals2, !ModeInfo),
modecheck_set_var_inst(X, Inst, yes(InstOfY), !ModeInfo),
UnifyArgInsts = list.map(func(I) = yes(I), InstOfXArgs),
bind_args(Inst, ArgVars, UnifyArgInsts, !ModeInfo)
;
set.list_to_set([X | ArgVars0], WaitingVars), % conservative
mode_info_error(WaitingVars,
mode_error_unify_var_functor(X, InstConsId, ArgVars0,
InstOfX, InstArgs),
!ModeInfo),
% If we get an error, set the inst to not_reached to avoid
% cascading errors. But don't call categorize_unification, because
% that could cause an invalid call to `unify_proc.request_unify'.
Inst = not_reached,
Det = erroneous,
ModeOfX = (InstOfX -> Inst),
ModeOfY = (InstOfY -> Inst),
Mode = ModeOfX - ModeOfY,
modecheck_set_var_inst(X, Inst, no, !ModeInfo),
NoArgInsts = list.duplicate(length(ArgVars0), no),
bind_args(Inst, ArgVars0, NoArgInsts, !ModeInfo),
% Return any old garbage.
Unification = Unification0,
ArgVars = ArgVars0,
ExtraGoals2 = no_extra_goals
),
%
% Optimize away construction of unused terms by replacing the unification
% with `true'. Optimize away unifications which always fail by replacing
% them with `fail'.
%
(
Unification = construct(_, _, _, _, _, _, _),
LiveX = dead
->
Goal = conj(plain_conj, [])
;
Det = failure
->
% This optimisation is safe because the only way that we can analyse
% a unification as having no solutions is that the unification always
% fails.
%
% Unifying two preds is not erroneous as far as the mode checker
% is concerned, but a mode _error_.
Goal = disj([]),
globals.io_lookup_bool_option(warn_unification_cannot_succeed,
WarnCannotSucceed, !IO),
(
WarnCannotSucceed = yes,
InitMayHaveSubtype = init_instmap_may_have_subtype(!.ModeInfo),
(
InitMayHaveSubtype = yes
% Suppress the warning, since the unification may succeed
% in another mode in which the initial inst of X,
% or of another head variable that is unified with it,
% is not so constrained.
;
InitMayHaveSubtype = no,
Warning = cannot_succeed_var_functor(X, InstOfX, ConsId),
mode_info_warning(Warning, !ModeInfo)
)
;
WarnCannotSucceed = no
)
;
Functor = functor(ConsId, IsExistConstruction, ArgVars),
Unify = unify(X, Functor, Mode, Unification, UnifyContext),
%
% Modecheck_unification sometimes needs to introduce new goals
% to handle complicated sub-unifications in deconstructions.
% The only time this can happen during unique mode analysis is if
% the instmap is unreachable, since inst_is_bound succeeds for
% not_reached. (If it did in other cases, the code would be wrong
% since it wouldn't have the correct determinism annotations.)
%
append_extra_goals(ExtraGoals0, ExtraGoals1, ExtraGoals01),
append_extra_goals(ExtraGoals01, ExtraGoals2, ExtraGoals),
(
HowToCheckGoal = check_unique_modes,
ExtraGoals \= no_extra_goals,
instmap.is_reachable(InstMap1)
->
unexpected(this_file,
"re-modecheck of unification " ++
"encountered complicated sub-unifies")
;
true
),
handle_extra_goals(Unify, ExtraGoals, GoalInfo0,
[X0 | ArgVars0], [X | ArgVars], InstMap0, Goal, !ModeInfo, !IO)
).
:- pred all_arg_vars_are_non_free_or_solver_vars(list(prog_var)::in,
list(mer_inst)::in, vartypes::in, module_info::in,
list(prog_var)::out) is semidet.
all_arg_vars_are_non_free_or_solver_vars([], [], _, _, []).
all_arg_vars_are_non_free_or_solver_vars([], [_|_], _, _, _) :-
unexpected(this_file,
"modecheck_unify.all_arg_vars_are_non_free_or_solver_vars: " ++
"mismatch in list lengths").
all_arg_vars_are_non_free_or_solver_vars([_|_], [], _, _, _) :-
unexpected(this_file,
"modecheck_unify.all_arg_vars_are_non_free_or_solver_vars: " ++
"mismatch in list lengths").
all_arg_vars_are_non_free_or_solver_vars([Arg | Args], [Inst | Insts],
VarTypes, ModuleInfo, ArgsToInit) :-
( inst_match.inst_is_free(ModuleInfo, Inst) ->
type_is_solver_type(ModuleInfo, VarTypes ^ elem(Arg)),
all_arg_vars_are_non_free_or_solver_vars(Args, Insts,
VarTypes, ModuleInfo, ArgsToInit1),
ArgsToInit = [Arg | ArgsToInit1]
;
all_arg_vars_are_non_free_or_solver_vars(Args, Insts,
VarTypes, ModuleInfo, ArgsToInit)
).
%-----------------------------------------------------------------------------%
% The argument unifications in a construction or deconstruction
% unification must be simple assignments, they cannot be
% complicated unifications. If they are, we split them out
% into separate unifications by introducing fresh variables here.
%
:- pred split_complicated_subunifies(unification::in, unification::out,
list(prog_var)::in, list(prog_var)::out, extra_goals::out,
mode_info::in, mode_info::out) is det.
split_complicated_subunifies(Unification0, Unification, ArgVars0, ArgVars,
ExtraGoals, !ModeInfo) :-
(
Unification0 = deconstruct(X, ConsId, ArgVars0, ArgModes0, Det, CanCGC)
->
(
split_complicated_subunifies_2(ArgVars0, ArgModes0,
ArgVars1, ExtraGoals1, !ModeInfo)
->
ExtraGoals = ExtraGoals1,
ArgVars = ArgVars1,
Unification = deconstruct(X, ConsId, ArgVars, ArgModes0, Det,
CanCGC)
;
unexpected(this_file, "split_complicated_subunifies_2 failed")
)
;
Unification = Unification0,
ArgVars = ArgVars0,
ExtraGoals = no_extra_goals
).
:- pred split_complicated_subunifies_2(list(prog_var)::in, list(uni_mode)::in,
list(prog_var)::out, extra_goals::out, mode_info::in, mode_info::out)
is semidet.
split_complicated_subunifies_2([], [], [], no_extra_goals, !ModeInfo).
split_complicated_subunifies_2([Var0 | Vars0], [UniMode0 | UniModes0],
Vars, ExtraGoals, !ModeInfo) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo),
UniMode0 = (InitialInstX - InitialInstY -> FinalInstX - FinalInstY),
ModeX = (InitialInstX -> FinalInstX),
ModeY = (InitialInstY -> FinalInstY),
mode_info_get_var_types(!.ModeInfo, VarTypes0),
map.lookup(VarTypes0, Var0, VarType),
(
mode_to_arg_mode(ModuleInfo, ModeX, VarType, top_in),
mode_to_arg_mode(ModuleInfo, ModeY, VarType, top_in)
->
make_complicated_sub_unify(Var0, Var, ExtraGoals0, !ModeInfo),
% Recursive call to handle the remaining variables...
split_complicated_subunifies_2(Vars0, UniModes0,
Vars1, ExtraGoals1, !ModeInfo),
Vars = [Var | Vars1],
append_extra_goals(ExtraGoals0, ExtraGoals1, ExtraGoals)
;
split_complicated_subunifies_2(Vars0, UniModes0, Vars1,
ExtraGoals, !ModeInfo),
Vars = [Var0 | Vars1]
).
:- pred make_complicated_sub_unify(prog_var::in, prog_var::out,
extra_goals::out, mode_info::in, mode_info::out) is det.
make_complicated_sub_unify(Var0, Var, ExtraGoals0, !ModeInfo) :-
% introduce a new variable `Var'
mode_info_get_varset(!.ModeInfo, VarSet0),
mode_info_get_var_types(!.ModeInfo, VarTypes0),
varset.new_var(VarSet0, Var, VarSet),
map.lookup(VarTypes0, Var0, VarType),
map.set(VarTypes0, Var, VarType, VarTypes),
mode_info_set_varset(VarSet, !ModeInfo),
mode_info_set_var_types(VarTypes, !ModeInfo),
create_var_var_unification(Var0, Var, VarType, !.ModeInfo, ExtraGoal),
% Insert the new unification at the start of the extra goals.
ExtraGoals0 = extra_goals([], [ExtraGoal]).
create_var_var_unification(Var0, Var, Type, ModeInfo, Goal - GoalInfo) :-
mode_info_get_context(ModeInfo, Context),
mode_info_get_mode_context(ModeInfo, ModeContext),
mode_context_to_unify_context(ModeInfo, ModeContext, UnifyContext),
UnifyContext = unify_context(MainContext, SubContexts),
create_atomic_complicated_unification(Var0, var(Var), Context,
MainContext, SubContexts, Goal0 - GoalInfo0),
%
% Compute the goal_info nonlocal vars for the newly created goal
% (excluding the type_info vars -- they are added below).
% N.B. This may overestimate the set of non-locals,
% but that shouldn't cause any problems.
%
set.list_to_set([Var0, Var], NonLocals),
goal_info_set_nonlocals(NonLocals, GoalInfo0, GoalInfo1),
goal_info_set_context(Context, GoalInfo1, GoalInfo2),
%
% Look up the map(tvar, type_info_locn) in the proc_info,
% since it is needed by polymorphism.unification_typeinfos.
%
mode_info_get_module_info(ModeInfo, ModuleInfo),
mode_info_get_predid(ModeInfo, PredId),
mode_info_get_procid(ModeInfo, ProcId),
module_info_pred_proc_info(ModuleInfo, PredId, ProcId,
_PredInfo, ProcInfo),
proc_info_rtti_varmaps(ProcInfo, RttiVarMaps),
%
% Call polymorphism.unification_typeinfos to add the appropriate
% type-info and type-class-info variables to the nonlocals
% and to the unification.
%
( Goal0 = unify(X, Y, Mode, Unification0, FinalUnifyContext) ->
polymorphism.unification_typeinfos(Type, RttiVarMaps,
Unification0, Unification, GoalInfo2, GoalInfo),
Goal = unify(X, Y, Mode, Unification, FinalUnifyContext)
;
unexpected(this_file, "modecheck_unify.create_var_var_unification")
).
%-----------------------------------------------------------------------------%
% categorize_unify_var_var works out which category a unification
% between a variable and another variable expression is - whether it is
% an assignment, a simple test or a complicated unify.
%
:- pred categorize_unify_var_var(mer_mode::in, mer_mode::in,
is_live::in, is_live::in, prog_var::in,
prog_var::in, determinism::in, unify_context::in, hlds_goal_info::in,
vartypes::in, unification::in, hlds_goal_expr::out,
mode_info::in, mode_info::out) is det.
categorize_unify_var_var(ModeOfX, ModeOfY, LiveX, LiveY, X, Y, Det,
UnifyContext, GoalInfo, VarTypes, Unification0, Unify, !ModeInfo) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
(
mode_is_output(ModuleInfo0, ModeOfX)
->
Unification = assign(X, Y)
;
mode_is_output(ModuleInfo0, ModeOfY)
->
Unification = assign(Y, X)
;
mode_is_unused(ModuleInfo0, ModeOfX),
mode_is_unused(ModuleInfo0, ModeOfY)
->
% For free-free unifications, we pretend for a moment that they are
% an assignment to the dead variable - they will then be optimized
% away.
( LiveX = dead ->
Unification = assign(X, Y)
; LiveY = dead ->
Unification = assign(Y, X)
;
unexpected(this_file, "categorize_unify_var_var: free-free unify!")
)
;
%
% Check for unreachable unifications
%
( mode_get_insts(ModuleInfo0, ModeOfX, not_reached, _)
; mode_get_insts(ModuleInfo0, ModeOfY, not_reached, _)
)
->
%
% For these, we can generate any old junk here --
% we just need to avoid calling modecheck_complicated_unify,
% since that might abort.
%
Unification = simple_test(X, Y)
;
map.lookup(VarTypes, X, Type),
(
type_is_atomic(Type, ModuleInfo0),
not type_has_user_defined_equality_pred(ModuleInfo0, Type, _)
->
Unification = simple_test(X, Y)
;
modecheck_complicated_unify(X, Y, Type, ModeOfX, ModeOfY, Det,
UnifyContext, Unification0, Unification, !ModeInfo)
)
),
% Optimize away unifications with dead variables and simple tests that
% cannot fail by replacing them with `true'. (The optimization of simple
% tests is necessary because otherwise determinism analysis assumes they
% can fail. The optimization of assignments to dead variables may be
% necessary to stop the code generator from getting confused.)
%
% Optimize away unifications which always fail by replacing them with
% `fail'.
(
Unification = assign(AssignTarget, AssignSource),
mode_info_var_is_live(!.ModeInfo, AssignTarget, dead)
->
Unify = conj(plain_conj, []),
record_optimize_away(GoalInfo, AssignTarget, AssignSource, !ModeInfo)
;
Unification = simple_test(TestVar1, TestVar2),
Det = det
->
Unify = conj(plain_conj, []),
record_optimize_away(GoalInfo, TestVar1, TestVar2, !ModeInfo)
;
Det = failure
->
% This optimisation is safe because the only way that we can analyse
% a unification as having no solutions is that the unification
% always fails.
%
% Unifying two preds is not erroneous as far as the
% mode checker is concerned, but a mode _error_.
Unify = disj([]),
mode_info_get_module_info(!.ModeInfo, ModuleInfo),
module_info_get_globals(ModuleInfo, Globals),
globals.lookup_bool_option(Globals, warn_unification_cannot_succeed,
WarnCannotSucceed),
(
WarnCannotSucceed = yes,
InitMayHaveSubtype = init_instmap_may_have_subtype(!.ModeInfo),
(
InitMayHaveSubtype = yes
% Suppress the warning, since the unification may succeed
% in another mode in which the initial inst of X or Y,
% or of another head variable that is unified with one of them,
% is not so constrained.
;
InitMayHaveSubtype = no,
mode_get_insts(ModuleInfo0, ModeOfX, InstOfX, _),
mode_get_insts(ModuleInfo0, ModeOfY, InstOfY, _),
Warning = cannot_succeed_var_var(X, Y, InstOfX, InstOfY),
mode_info_warning(Warning, !ModeInfo)
)
;
WarnCannotSucceed = no
)
;
Unify = unify(X, var(Y), ModeOfX - ModeOfY, Unification, UnifyContext)
).
% If we optimize away a singleton variable in a unification in one branch
% of e.g. a switch, it is possible that the same variable is a singleton
% in another branch, but cannot be optimized away because it is bound in
% a call (which cannot be optimized away). In such cases, we must make sure
% that we call requantification to delete the variable from the nonlocals
% set of the switch, because otherwise, the arms of the switch would
% disagree on which nonlocals are bound.
%
:- pred record_optimize_away(hlds_goal_info::in, prog_var::in, prog_var::in,
mode_info::in, mode_info::out) is det.
record_optimize_away(GoalInfo, Var1, Var2, !ModeInfo) :-
goal_info_get_nonlocals(GoalInfo, NonLocals),
(
set.member(Var1, NonLocals),
set.member(Var2, NonLocals)
->
true
;
mode_info_need_to_requantify(!ModeInfo)
).
% Modecheck_complicated_unify does some extra checks that are needed
% for mode-checking complicated unifications.
%
:- pred modecheck_complicated_unify(prog_var::in, prog_var::in,
mer_type::in, mer_mode::in, mer_mode::in, determinism::in,
unify_context::in, unification::in, unification::out,
mode_info::in, mode_info::out) is det.
modecheck_complicated_unify(X, Y, Type, ModeOfX, ModeOfY, Det, UnifyContext,
Unification0, Unification, !ModeInfo) :-
% Build up the unification.
mode_info_get_module_info(!.ModeInfo, ModuleInfo0),
mode_get_insts(ModuleInfo0, ModeOfX, InitialInstX, FinalInstX),
mode_get_insts(ModuleInfo0, ModeOfY, InitialInstY, FinalInstY),
UniMode = ((InitialInstX - InitialInstY) -> (FinalInstX - FinalInstY)),
determinism_components(Det, CanFail, _),
( Unification0 = complicated_unify(_, _, UnifyTypeInfoVars0) ->
UnifyTypeInfoVars = UnifyTypeInfoVars0
;
unexpected(this_file, "modecheck_complicated_unify")
),
Unification = complicated_unify(UniMode, CanFail, UnifyTypeInfoVars),
% Check that all the type_info or type_class_info variables used
% by the polymorphic unification are ground.
(
% Optimize common case.
UnifyTypeInfoVars = []
;
UnifyTypeInfoVars = [_ | _],
list.length(UnifyTypeInfoVars, NumTypeInfoVars),
list.duplicate(NumTypeInfoVars, ground(shared, none), ExpectedInsts),
mode_info_set_call_context(unify(UnifyContext), !ModeInfo),
NeedExactMatch = no,
InitialArgNum = 0,
modecheck_var_has_inst_list(UnifyTypeInfoVars, ExpectedInsts,
NeedExactMatch, InitialArgNum, _InstVarSub, !ModeInfo),
% we can ignore _InstVarSub since type_info variables
% should not have variable insts.
mode_info_unset_call_context(!ModeInfo)
),
mode_info_get_module_info(!.ModeInfo, ModuleInfo3),
(
mode_info_get_errors(!.ModeInfo, Errors),
Errors \= []
->
true
;
% Check that we're not trying to do a polymorphic unification
% in a mode other than (in, in).
% [Actually we also allow `any' insts, since the (in, in)
% mode of unification for types which have `any' insts must
% also be able to handle (in(any), in(any)) unifications.]
Type = variable(_, _),
\+ inst_is_ground_or_any(ModuleInfo3, InitialInstX)
->
set.singleton_set(WaitingVars, X),
mode_info_error(WaitingVars, mode_error_poly_unify(X, InitialInstX),
!ModeInfo)
;
Type = variable(_, _),
\+ inst_is_ground_or_any(ModuleInfo3, InitialInstY)
->
set.singleton_set(WaitingVars, Y),
mode_info_error(WaitingVars, mode_error_poly_unify(Y, InitialInstY),
!ModeInfo)
;
% Check that we're not trying to do a higher-order unification.
type_is_higher_order(Type, _, PredOrFunc, _, _)
->
% We do not want to report this as an error if it occurs in a
% compiler-generated predicate - instead, we delay the error
% until runtime so that it only occurs if the compiler-generated
% predicate gets called. not_reached is considered bound, so the
% error message would be spurious if the instmap is unreachable.
mode_info_get_predid(!.ModeInfo, PredId),
module_info_pred_info(ModuleInfo3, PredId, PredInfo),
mode_info_get_instmap(!.ModeInfo, InstMap0),
(
( is_unify_or_compare_pred(PredInfo)
; instmap.is_unreachable(InstMap0)
)
->
true
;
set.init(WaitingVars),
mode_info_error(WaitingVars,
mode_error_unify_pred(X, error_at_var(Y), Type, PredOrFunc),
!ModeInfo)
)
;
% Ensure that we will generate code for the unification procedure
% that will be used to implement this complicated unification.
type_to_ctor_and_args(Type, TypeCtor, _)
->
mode_info_get_context(!.ModeInfo, Context),
mode_info_get_instvarset(!.ModeInfo, InstVarSet),
unify_proc.request_unify(TypeCtor - UniMode, InstVarSet,
Det, Context, ModuleInfo3, ModuleInfo),
mode_info_set_module_info(ModuleInfo, !ModeInfo)
;
true
).
% Categorize_unify_var_lambda works out which category a unification
% between a variable and a lambda expression is - whether it is a
% construction unification or a deconstruction. It also works out
% whether it will be deterministic or semideterministic.
%
:- pred categorize_unify_var_lambda(mer_mode::in, list(mer_mode)::in,
prog_var::in, list(prog_var)::in, pred_or_func::in,
unify_rhs::in, unify_rhs::out, unification::in, unification::out,
mode_info::in, mode_info::out) is det.
categorize_unify_var_lambda(ModeOfX, ArgModes0, X, ArgVars, PredOrFunc,
RHS0, RHS, Unification0, Unification, !ModeInfo) :-
% If we are re-doing mode analysis, preserve the existing cons_id.
list.length(ArgVars, Arity),
(
Unification0 = construct(_, ConsId0, _, _, _, _, SubInfo0)
->
(
SubInfo0 = construct_sub_info(MaybeTakeAddr, _MaybeSize),
expect(unify(MaybeTakeAddr, no), this_file,
"categorize_unify_var_lambda: take_addr")
;
SubInfo0 = no_construct_sub_info
),
SubInfo = SubInfo0,
ConsId = ConsId0
;
Unification0 = deconstruct(_, ConsId1, _, _, _, _)
->
SubInfo = no_construct_sub_info,
ConsId = ConsId1
;
% The real cons_id will be computed by lambda.m;
% we just put in a dummy one for now.
SubInfo = no_construct_sub_info,
ConsId = cons(unqualified("__LambdaGoal__"), Arity)
),
mode_info_get_module_info(!.ModeInfo, ModuleInfo),
mode_util.modes_to_uni_modes(ModuleInfo, ArgModes0, ArgModes0, ArgModes),
mode_info_get_instmap(!.ModeInfo, InstMap),
( mode_is_output(ModuleInfo, ModeOfX) ->
(
% If pred_consts are present, lambda expansion has already been
% done. Rerunning mode analysis should not produce a lambda_goal
% which cannot be directly converted back into a higher-order
% predicate constant. If the instmap is not reachable, the call
% may have been handled as an implied mode, since not_reached
% is considered to be bound. In this case the lambda_goal may
% not be converted back to a predicate constant, but that doesn't
% matter since the code will be pruned away later by simplify.m.
ConsId = pred_const(ShroudedPredProcId, EvalMethod),
instmap.is_reachable(InstMap)
->
proc(PredId, ProcId) =
unshroud_pred_proc_id(ShroudedPredProcId),
(
RHS0 = lambda_goal(_, _, EvalMethod, _, _, _, _, Goal),
Goal = call(PredId, ProcId, _, _, _, _) - _
->
module_info_pred_info(ModuleInfo, PredId, PredInfo),
PredModule = pred_info_module(PredInfo),
PredName = pred_info_name(PredInfo),
RHS = functor(cons(qualified(PredModule, PredName), Arity),
no, ArgVars)
;
unexpected(this_file,
"categorize_unify_var_lambda - reintroduced lambda goal")
)
;
RHS = RHS0
),
Unification = construct(X, ConsId, ArgVars, ArgModes,
construct_dynamically, cell_is_unique, SubInfo)
; instmap.is_reachable(InstMap) ->
% If it's a deconstruction, it is a mode error.
% The error message would be incorrect in unreachable code,
% since not_reached is considered bound.
set.init(WaitingVars),
mode_info_get_var_types(!.ModeInfo, VarTypes0),
map.lookup(VarTypes0, X, Type),
mode_info_error(WaitingVars,
mode_error_unify_pred(X, error_at_lambda(ArgVars, ArgModes0),
Type, PredOrFunc),
!ModeInfo),
% Return any old garbage.
Unification = Unification0,
RHS = RHS0
;
Unification = Unification0,
RHS = RHS0
).
% Categorize_unify_var_functor works out which category a unification
% between a variable and a functor is - whether it is a construction
% unification or a deconstruction. It also works out whether it will be
% deterministic or semideterministic.
:- pred categorize_unify_var_functor(mer_mode::in, list(mer_mode)::in,
list(mer_mode)::in, prog_var::in, cons_id::in, list(prog_var)::in,
vartypes::in, unify_context::in,
unification::in, unification::out,
mode_info::in, mode_info::out) is det.
categorize_unify_var_functor(ModeOfX, ModeOfXArgs, ArgModes0,
X, NewConsId, ArgVars, VarTypes, UnifyContext,
Unification0, Unification, !ModeInfo) :-
mode_info_get_module_info(!.ModeInfo, ModuleInfo),
map.lookup(VarTypes, X, TypeOfX),
% If we are re-doing mode analysis, preserve the existing cons_id.
(
Unification0 = construct(_, ConsId0, _, _, _, _, SubInfo0)
->
(
SubInfo0 = construct_sub_info(MaybeTakeAddr, _MaybeSize0),
expect(unify(MaybeTakeAddr, no), this_file,
"categorize_unify_var_functor: take_addr")
;
SubInfo0 = no_construct_sub_info
),
SubInfo = SubInfo0,
ConsId = ConsId0
;
Unification0 = deconstruct(_, ConsId1, _, _, _, _)
->
SubInfo = no_construct_sub_info,
ConsId = ConsId1
;
SubInfo = no_construct_sub_info,
ConsId = NewConsId
),
mode_util.modes_to_uni_modes(ModuleInfo, ModeOfXArgs,
ArgModes0, ArgModes),
( mode_is_output(ModuleInfo, ModeOfX) ->
% It's a construction.
Unification = construct(X, ConsId, ArgVars, ArgModes,
construct_dynamically, cell_is_unique, SubInfo),
% For existentially quantified data types, check that any type_info
% or type_class_info variables in the construction are ground.
check_type_info_args_are_ground(ArgVars, VarTypes,
UnifyContext, !ModeInfo)
;
% It's a deconstruction.
(
% If the variable was already known to be bound to a single
% particular functor, then the unification either always succeeds
% or always fails. In the latter case, the final inst will be
% `not_reached' or `bound([])'. So if both the initial and final
% inst are `bound([_])', then the unification must be
% deterministic.
mode_get_insts(ModuleInfo, ModeOfX,
InitialInst0, FinalInst0),
inst_expand(ModuleInfo, InitialInst0, InitialInst),
inst_expand(ModuleInfo, FinalInst0, FinalInst),
InitialInst = bound(_, [_]),
FinalInst = bound(_, [_])
->
CanFail = cannot_fail
;
% If the type has only one constructor, then the unification
% cannot fail.
type_constructors(TypeOfX, ModuleInfo, Constructors),
Constructors = [_]
->
CanFail = cannot_fail
;
% Otherwise, it can fail.
CanFail = can_fail,
mode_info_get_instmap(!.ModeInfo, InstMap0),
(
type_is_higher_order(TypeOfX, _, PredOrFunc, _, _),
instmap.is_reachable(InstMap0)
->
set.init(WaitingVars),
mode_info_error(WaitingVars,
mode_error_unify_pred(X, error_at_functor(ConsId, ArgVars),
TypeOfX, PredOrFunc),
!ModeInfo)
;
true
)
),
Unification = deconstruct(X, ConsId, ArgVars, ArgModes, CanFail,
cannot_cgc)
).
% Check that any type_info or type_class_info variables
% in the argument list are ground.
%
:- pred check_type_info_args_are_ground(list(prog_var)::in,
vartypes::in, unify_context::in,
mode_info::in, mode_info::out) is det.
check_type_info_args_are_ground([], _VarTypes, _UnifyContext, !ModeInfo).
check_type_info_args_are_ground([ArgVar | ArgVars], VarTypes, UnifyContext,
!ModeInfo) :-
(
map.lookup(VarTypes, ArgVar, ArgType),
is_introduced_type_info_type(ArgType)
->
mode_info_set_call_context(unify(UnifyContext), !ModeInfo),
NeedExactMatch = no,
InitialArgNum = 0,
modecheck_var_has_inst_list([ArgVar], [ground(shared, none)],
NeedExactMatch, InitialArgNum, _InstVarSub, !ModeInfo),
check_type_info_args_are_ground(ArgVars, VarTypes, UnifyContext,
!ModeInfo),
mode_info_unset_call_context(!ModeInfo)
;
true
).
%-----------------------------------------------------------------------------%
:- pred bind_args(mer_inst::in, list(prog_var)::in, list(maybe(mer_inst))::in,
mode_info::in, mode_info::out) is det.
bind_args(Inst, Args, UnifyArgInsts, !ModeInfo) :-
( try_bind_args(Inst, Args, UnifyArgInsts, !ModeInfo) ->
true
;
unexpected(this_file, "bind_args: try_bind_args failed")
).
:- pred try_bind_args(mer_inst::in, list(prog_var)::in,
list(maybe(mer_inst))::in, mode_info::in, mode_info::out) is semidet.
try_bind_args(not_reached, _, _, !ModeInfo) :-
instmap.init_unreachable(InstMap),
mode_info_set_instmap(InstMap, !ModeInfo).
try_bind_args(ground(Uniq, none), Args, UnifyArgInsts, !ModeInfo) :-
ground_args(Uniq, Args, UnifyArgInsts, !ModeInfo).
try_bind_args(bound(_Uniq, List), Args, UnifyArgInsts, !ModeInfo) :-
(
List = [],
% The code is unreachable.
instmap.init_unreachable(InstMap),
mode_info_set_instmap(InstMap, !ModeInfo)
;
List = [_ | _],
List = [functor(_, InstList)],
try_bind_args_2(Args, InstList, UnifyArgInsts, !ModeInfo)
).
try_bind_args(constrained_inst_vars(_, Inst), Args, UnifyArgInsts,
!ModeInfo) :-
try_bind_args(Inst, Args, UnifyArgInsts, !ModeInfo).
:- pred try_bind_args_2(list(prog_var)::in, list(mer_inst)::in,
list(maybe(mer_inst))::in, mode_info::in, mode_info::out) is semidet.
try_bind_args_2([], [], [], !ModeInfo).
try_bind_args_2([Arg | Args], [Inst | Insts], [UnifyArgInst | UnifyArgInsts],
!ModeInfo) :-
modecheck_set_var_inst(Arg, Inst, UnifyArgInst, !ModeInfo),
try_bind_args_2(Args, Insts, UnifyArgInsts, !ModeInfo).
:- pred ground_args(uniqueness::in, list(prog_var)::in,
list(maybe(mer_inst))::in, mode_info::in, mode_info::out) is semidet.
ground_args(_Uniq, [], [], !ModeInfo).
ground_args(Uniq, [Arg | Args], [UnifyArgInst | UnifyArgInsts], !ModeInfo) :-
modecheck_set_var_inst(Arg, ground(Uniq, none), UnifyArgInst, !ModeInfo),
ground_args(Uniq, Args, UnifyArgInsts, !ModeInfo).
%-----------------------------------------------------------------------------%
% get_mode_of_args(FinalInst, InitialArgInsts, ArgModes):
%
% For a var-functor unification, given the final inst of the var
% and the initial insts of the functor arguments, compute the modes
% of the functor arguments.
%
:- pred get_mode_of_args(mer_inst::in, list(mer_inst)::in, list(mer_mode)::out)
is semidet.
get_mode_of_args(not_reached, ArgInsts, ArgModes) :-
mode_set_args(ArgInsts, not_reached, ArgModes).
get_mode_of_args(any(Uniq), ArgInsts, ArgModes) :-
mode_set_args(ArgInsts, any(Uniq), ArgModes).
get_mode_of_args(ground(Uniq, none), ArgInsts, ArgModes) :-
mode_set_args(ArgInsts, ground(Uniq, none), ArgModes).
get_mode_of_args(bound(_Uniq, List), ArgInstsA, ArgModes) :-
(
List = [],
% The code is unreachable.
mode_set_args(ArgInstsA, not_reached, ArgModes)
;
List = [_ | _],
List = [functor(_Name, ArgInstsB)],
get_mode_of_args_2(ArgInstsA, ArgInstsB, ArgModes)
).
get_mode_of_args(constrained_inst_vars(_, Inst), ArgInsts, ArgModes) :-
get_mode_of_args(Inst, ArgInsts, ArgModes).
:- pred get_mode_of_args_2(list(mer_inst)::in, list(mer_inst)::in,
list(mer_mode)::out) is semidet.
get_mode_of_args_2([], [], []).
get_mode_of_args_2([InstA | InstsA], [InstB | InstsB], [Mode | Modes]) :-
Mode = (InstA -> InstB),
get_mode_of_args_2(InstsA, InstsB, Modes).
:- pred mode_set_args(list(mer_inst)::in, mer_inst::in, list(mer_mode)::out)
is det.
mode_set_args([], _, []).
mode_set_args([Inst | Insts], FinalInst, [Mode | Modes]) :-
Mode = (Inst -> FinalInst),
mode_set_args(Insts, FinalInst, Modes).
%-----------------------------------------------------------------------------%
:- func init_instmap_may_have_subtype(mode_info) = bool.
init_instmap_may_have_subtype(ModeInfo) = MayHaveSubtype :-
mode_info_get_initial_instmap(ModeInfo, InitialInstMap),
instmap.to_assoc_list(InitialInstMap, InitVarsInsts),
assoc_list.values(InitVarsInsts, InitInsts),
mode_info_get_module_info(ModeInfo, ModuleInfo),
MayRestrictList =
list.map(inst_may_restrict_cons_ids(ModuleInfo), InitInsts),
bool.or_list(MayRestrictList, MayHaveSubtype).
%-----------------------------------------------------------------------------%
:- func this_file = string.
this_file = "modecheck_unify.m".
%-----------------------------------------------------------------------------%
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