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var_use_analysis.m
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var_use_analysis.m
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%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 2008, 2010-2012 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.
%-----------------------------------------------------------------------------%
%
% Authors: pbone, zs.
%
% This file implements the coverage propagation algorithm, which attaches
% coverage information to the component goals of a procedure body.
%
% This module can be compiled with the following trace flag to enable
% debugging: debug_first_var_use. See Mercury.options in this directory.
%
%-----------------------------------------------------------------------------%
:- module var_use_analysis.
:- interface.
:- import_module analysis_utils.
:- import_module mdbcomp.
:- import_module mdbcomp.goal_path.
:- import_module mdbcomp.program_representation.
:- import_module coverage.
:- import_module measurements.
:- import_module profile.
:- import_module report.
:- import_module list.
:- import_module map.
:- import_module maybe.
:- import_module set.
% Gives information about the use of a variable measured in average call
% sequence counts since either the beginning or the end of the procedure.
%
:- type var_use_info
---> var_use_info(
vui_cost_until_use :: float,
vui_proc_cost :: float,
vui_use_type :: var_use_type
).
:- type var_use_options
---> var_use_options(
vuo_deep :: deep,
vuo_intermodule_var_use :: intermodule_var_use,
vuo_var_use_type :: var_use_type
).
:- type intermodule_var_use
---> follow_calls_into_module(string)
; follow_any_call.
:- type var_use_type
---> var_use_production
% The variable is produced: free >> ground
; var_use_consumption
% The variable is consumed: free >> free
; var_use_other.
% The variable is used in some other way.
%-----------------------------------------------------------------------------%
:- func average_var_use(list(var_use_info)) = var_use_info.
:- pred var_mode_to_var_use_type(var_mode_rep::in, var_use_type::out) is det.
:- pred pessimistic_var_use_info(var_use_type::in, float::in,
var_use_info::out) is det.
:- pred pessimistic_var_use_time(var_use_type::in, float::in, float::out)
is det.
%-----------------------------------------------------------------------------%
% call_site_dynamic_var_use_info(Deep, CSDPtr, ArgPos, RT, VarUseType,
% MaybeVarUseInfo):
%
% Lookup when the call site CSDPtr will produce ArgPos. RT is the type of
% recursion in the call site's parent clique and VarUseType is the type of
% variable use that is expected, VarUseType is used to produce conservative
% defaults if a callee cannot be analyzed.
%
% The first mode avoids a check to ensure that this recursion type provides
% enough information.
%
:- pred call_site_dynamic_var_use_info(call_site_dynamic_ptr, int,
recursion_type, float, var_use_options, maybe_error(var_use_info)).
:- mode call_site_dynamic_var_use_info(in, in,
in(recursion_type_known_costs), in, in, out) is det.
:- mode call_site_dynamic_var_use_info(in, in,
in, in, in, out) is det.
% call_site_dynamic_var_use_info(Deep, CliquePtr, CSDPtr, ArgPos, RT,
% MaybeCurDepth, Cost, CallStack, VarUseType, MaybeVarUseInfo).
%
% As above. This alternative should be used if searching starts at a
% different recursion level or from within a current variable use analysis.
%
% CliquePtr is the current clique, MaybeCurDepth is the current recursion
% depth within the clique if known, CallStack is the set of proc dynamics
% that have already been explored.
%
% Cost is the cost of the call.
%
:- pred call_site_dynamic_var_use_info(clique_ptr, call_site_dynamic_ptr,
int, recursion_type, maybe(recursion_depth), float, set(proc_dynamic_ptr),
var_use_options, maybe_error(var_use_info)).
:- mode call_site_dynamic_var_use_info(in, in, in,
in(recursion_type_known_costs), in(maybe_yes(ground)), in, in, in, out)
is det.
:- mode call_site_dynamic_var_use_info(in, in, in,
in, in, in, in, in, out) is det.
:- pred clique_var_use_info(clique_ptr::in, int::in,
var_use_options::in, maybe_error(var_use_info)::out) is det.
:- pred proc_dynamic_var_use_info(clique_ptr::in,
proc_dynamic_ptr::in, int::in,
recursion_type::in(recursion_type_known_costs), recursion_depth::in,
float::in, set(proc_dynamic_ptr)::in, var_use_options::in,
maybe_error(var_use_info)::out) is det.
%-----------------------------------------------------------------------------%
% Find the first use of a variable in an arbitrary goal.
%
:- pred var_first_use(clique_ptr::in,
map(reverse_goal_path, cost_and_callees)::in,
map(reverse_goal_path, cs_cost_csq)::in,
containing_goal_map::in, goal_attr_array(coverage_info)::in,
recursion_type::in(recursion_type_known_costs), recursion_depth::in,
goal_rep(goal_id)::in, reverse_goal_path::in, float::in, var_rep::in,
var_use_options::in, var_use_info::out) is det.
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module measurement_units.
:- import_module program_representation_utils.
:- import_module recursion_patterns.
:- import_module assoc_list.
:- import_module float.
:- import_module int.
:- import_module io.
:- import_module pair.
:- import_module require.
:- import_module solutions.
:- import_module string.
%-----------------------------------------------------------------------------%
average_var_use(Uses) = var_use_info(CostUntilUse, AvgProcCost, Type) :-
(
Uses = [],
unexpected($module, $pred, "cannot average zero items")
;
Uses = [var_use_info(_, _, Type) | _],
foldl2(sum_use_info_costs, Uses, 0.0, SumCost, 0.0, SumProcCost),
Num = float(length(Uses)),
CostUntilUse = SumCost / Num,
AvgProcCost = SumProcCost / Num,
TestType =
( pred(var_use_info(_, _, TypeI)::in) is semidet :-
Type = TypeI
),
( all_true(TestType, Uses) ->
true
;
unexpected($module, $pred, "use types do not match")
)
).
:- pred sum_use_info_costs(var_use_info::in, float::in, float::out,
float::in, float::out) is det.
sum_use_info_costs(var_use_info(Cost, ProcCost, _), !AccCost, !AccProcCost) :-
!:AccCost = !.AccCost + Cost,
!:AccProcCost = !.AccProcCost + ProcCost.
%-----------------------------------------------------------------------------%
var_mode_to_var_use_type(var_mode_rep(InitialInst, FinalInst), VarUseType) :-
(
InitialInst = ir_ground_rep,
FinalInst = ir_ground_rep
->
VarUseType = var_use_consumption
;
InitialInst = ir_free_rep,
FinalInst = ir_ground_rep
->
VarUseType = var_use_production
;
VarUseType = var_use_other
).
%-----------------------------------------------------------------------------%
pessimistic_var_use_info(VarUseType, ProcCost, VarUseInfo) :-
pessimistic_var_use_time(VarUseType, ProcCost, CostUntilUse),
VarUseInfo = var_use_info(CostUntilUse, ProcCost, VarUseType).
pessimistic_var_use_time(VarUseType, ProcCost, CostUntilUse) :-
(
VarUseType = var_use_consumption,
CostUntilUse = 0.0
;
( VarUseType = var_use_production
; VarUseType = var_use_other
),
CostUntilUse = ProcCost
).
%-----------------------------------------------------------------------------%
% XXX: If the CSD represents a closure then the argument position will be
% incorrect. This is not currently important as we assume that the
% compiler will not push signals and waits into higher order calls.
% Therefore this should never be called for a higher order call site.
%
call_site_dynamic_var_use_info(CSDPtr, ArgPos, RT, Cost, VarUseOptions,
MaybeVarUseInfo) :-
Deep = VarUseOptions ^ vuo_deep,
deep_lookup_call_site_dynamics(Deep, CSDPtr, CSD),
deep_lookup_clique_index(Deep, CSD ^ csd_caller, ParentCliquePtr),
recursion_type_get_maybe_avg_max_depth(RT, MaybeCurDepth),
call_site_dynamic_var_use_info(ParentCliquePtr, CSDPtr, ArgPos, RT,
MaybeCurDepth, Cost, set.init, VarUseOptions, MaybeVarUseInfo).
call_site_dynamic_var_use_info(ParentCliquePtr, CSDPtr, ArgNum,
RecursionType, MaybeDepth, Cost, CallStack0, VarUseOptions,
MaybeVarUseInfo) :-
Deep = VarUseOptions ^ vuo_deep,
deep_lookup_clique_maybe_child(Deep, CSDPtr, MaybeCalleeCliquePtr),
(
MaybeCalleeCliquePtr = yes(CalleeCliquePtr),
% This is a non-recursive call site.
% We don't check if this call crossed a module boundary here, that's
% done in clique_var_use_info.
clique_var_use_info(CalleeCliquePtr, ArgNum, VarUseOptions,
MaybeVarUseInfo)
;
MaybeCalleeCliquePtr = no,
% This is a recursive call site.
deep_lookup_call_site_dynamics(Deep, CSDPtr, CSD),
CalleePDPtr = CSD ^ csd_callee,
( not intermodule_var_use_should_follow_csd(VarUseOptions, CSDPtr) ->
% Don't follow this call across module boundaries.
pessimistic_var_use_info(VarUseOptions ^ vuo_var_use_type, Cost,
VarUseInfo),
MaybeVarUseInfo = ok(VarUseInfo)
; member(CalleePDPtr, CallStack0) ->
% Return a first use time of 1.0. This is used by the formula
% below.
MaybeVarUseInfo = ok(var_use_info(1.0, Cost,
VarUseOptions ^ vuo_var_use_type))
;
(
MaybeDepth = yes(Depth0),
recursion_depth_descend(Depth0, Depth),
(
( RecursionType = rt_not_recursive
; RecursionType = rt_single(_, _, _, _, _)
),
% Don't follow this recursive call as normal, doing so
% would make this analysis take too long. We can compute
% the cost of variable use time by the following formula:
set.insert(CalleePDPtr, CallStack0, CallStack),
proc_dynamic_recursive_var_use_info(ParentCliquePtr,
CalleePDPtr, ArgNum, RecursionType, Depth, Cost,
CallStack, VarUseOptions, MaybeVarUseInfo0),
(
MaybeVarUseInfo0 = ok(var_use_info(UseTime0, ProcTime0,
UseType)),
UseTime = UseTime0 + 1.0,
ProcTime = ProcTime0 + 1.0,
% Add a call sequence count for the cost of this call.
MaybeVarUseInfo = ok(var_use_info(UseTime, ProcTime,
UseType))
;
MaybeVarUseInfo0 = error(_),
MaybeVarUseInfo = MaybeVarUseInfo0
)
;
( RecursionType = rt_divide_and_conquer(_, _)
; RecursionType = rt_mutual_recursion(_)
; RecursionType = rt_other(_)
; RecursionType = rt_errors(_)
),
MaybeVarUseInfo = error(
"Cannot compute var use on a recursive call site "
++ "for an unknown recursion type")
)
;
MaybeDepth = no,
MaybeVarUseInfo = error(
"Cannot compute var use on a recursive call site "
++ "for an unknown recursion depth")
)
)
).
clique_var_use_info(CliquePtr, ArgNum, VarUseOptions, MaybeVarUseInfo) :-
Deep = VarUseOptions ^ vuo_deep,
deep_lookup_clique_parents(Deep, CliquePtr, CSDPtr),
deep_lookup_csd_desc(Deep, CSDPtr, CSDDesc),
Cost = float(inherit_callseqs(CSDDesc)),
find_clique_first_and_other_procs(Deep, CliquePtr, MaybeFirstProc,
_OtherProcs),
(
MaybeFirstProc = yes(FirstPDPtr),
VarUseType = VarUseOptions ^ vuo_var_use_type,
( intermodule_var_use_should_follow_csd(VarUseOptions, CSDPtr) ->
create_clique_recursion_costs_report(Deep, CliquePtr,
MaybeRecursionReport),
(
MaybeRecursionReport = ok(RecursionReport),
RecursionType = RecursionReport ^ crr_recursion_type
;
MaybeRecursionReport = error(Error),
RecursionType = rt_errors([Error])
),
(
(
RecursionType = rt_not_recursive,
recursion_type_get_maybe_avg_max_depth(RecursionType,
yes(Depth)),
% XXX: This shouldn't need the recursion information
% anymore.
proc_dynamic_var_use_info(CliquePtr, FirstPDPtr,
ArgNum, RecursionType, Depth, Cost, set.init,
VarUseOptions, MaybeVarUseInfo0)
;
RecursionType = rt_single(_, _, _, _, _),
recursion_type_get_maybe_avg_max_depth(RecursionType,
yes(Depth)),
% Add this PD to the proc dynamic pointer, we don't use a
% second recursion in this case.
proc_dynamic_recursive_var_use_info(CliquePtr, FirstPDPtr,
ArgNum, RecursionType, Depth, Cost, set([FirstPDPtr]),
VarUseOptions, MaybeVarUseInfo0)
),
(
MaybeVarUseInfo0 = ok(var_use_info(UseTime0, ProcTime0,
UseType)),
UseTime = UseTime0 + 1.0,
ProcTime = ProcTime0 + 1.0,
% Add a call sequence count for the cost of this call.
MaybeVarUseInfo = ok(var_use_info(UseTime, ProcTime,
UseType))
;
MaybeVarUseInfo0 = error(_),
MaybeVarUseInfo = MaybeVarUseInfo0
)
;
( RecursionType = rt_divide_and_conquer(_, _)
; RecursionType = rt_mutual_recursion(_)
; RecursionType = rt_other(_)
; RecursionType = rt_errors(_)
),
pessimistic_var_use_info(VarUseType, Cost, VarUseInfo),
MaybeVarUseInfo = ok(VarUseInfo)
)
;
pessimistic_var_use_info(VarUseType, Cost, VarUseInfo),
MaybeVarUseInfo = ok(VarUseInfo)
)
;
MaybeFirstProc = no,
unexpected($module, $pred, "clique has no first procedure")
).
proc_dynamic_var_use_info(CliquePtr, PDPtr, ArgNum, RecursionType,
Depth, ProcCost, CallStack, VarUseOptions, MaybeVarUseInfo) :-
prepare_for_proc_var_first_use(CliquePtr, PDPtr, ArgNum, RecursionType,
Depth, VarUseOptions, Info),
(
Info = proc_var_first_use_prepared_info(Goal, _LastGoalId,
ContainingGoalMap, CoverageArray, CallSiteCostMap,
RecursiveCallSiteCostMap, Var),
goal_var_first_use_wrapper(CliquePtr, CallStack,
ContainingGoalMap, CoverageArray, CallSiteCostMap,
RecursiveCallSiteCostMap, RecursionType, Depth, Goal, ProcCost,
Var, VarUseOptions, VarUseInfo),
MaybeVarUseInfo = ok(VarUseInfo)
;
Info = error(Error),
MaybeVarUseInfo = error(Error)
).
% Like proc_dynamic_recursive_var_use_info except that it handles recursive
% code by induction.
%
% UseTime = BaseUseTime + (RecUseTime + 1.0) * Depth
%
% Where BaseUseTime is the use time in the base case execution and
% RecUseTime is the use time before the recursive call. This works for any
% self-recursion pattern.
%
:- pred proc_dynamic_recursive_var_use_info(clique_ptr::in,
proc_dynamic_ptr::in, int::in,
recursion_type::in(recursion_type_known_costs), recursion_depth::in,
float::in, set(proc_dynamic_ptr)::in, var_use_options::in,
maybe_error(var_use_info)::out) is det.
proc_dynamic_recursive_var_use_info(CliquePtr, PDPtr, ArgNum,
RecursionType, Depth, _Cost, CallStack, VarUseOptions,
MaybeVarUseInfo) :-
prepare_for_proc_var_first_use(CliquePtr, PDPtr, ArgNum, RecursionType,
Depth, VarUseOptions, Info),
(
Info = proc_var_first_use_prepared_info(Goal, LastGoalId,
ContainingGoalMap, CoverageArray, CallSiteCostMap,
RecursiveCallSiteCostMap, Var),
VarUseInfo = var_first_use_static_info(CliquePtr,
CallSiteCostMap, RecursiveCallSiteCostMap, ContainingGoalMap,
CoverageArray, Var, VarUseOptions, CallStack, RecursionType, Depth,
no_recursion_info),
RecProbsArray0 = create_goal_id_array(LastGoalId, impossible),
build_recursive_call_sites_list(RecursiveCallSiteCostMap,
RecursiveCalls),
goal_rec_prob(Goal, RecursiveCalls, VarUseInfo, RecProb,
RecProbsArray0, RecProbsArray),
VarFirstUseInfoRecCase = VarUseInfo ^ fui_rec_info :=
first_use_rec_info(RecProbsArray, recursive_case),
rec_goal_var_first_use(Goal, RecursiveCalls, VarFirstUseInfoRecCase,
RecFoundFirstUse, 0.0, RecTotalTime),
VarFirstUseInfoBaseCase = VarUseInfo ^ fui_rec_info :=
first_use_rec_info(RecProbsArray, base_case),
rec_goal_var_first_use(Goal, RecursiveCalls, VarFirstUseInfoBaseCase,
BaseFoundFirstUse, 0.0, BaseTotalTime),
VarUseType = VarUseOptions ^ vuo_var_use_type,
(
RecFoundFirstUse = found_first_use(VarUseTimeRec)
;
RecFoundFirstUse = have_not_found_first_use,
(
VarUseType = var_use_consumption,
VarUseTimeRec = 0.0
;
( VarUseType = var_use_production
; VarUseType = var_use_other
),
VarUseTimeRec = RecTotalTime
)
),
(
BaseFoundFirstUse = found_first_use(VarUseTimeBase)
;
BaseFoundFirstUse = have_not_found_first_use,
(
VarUseType = var_use_consumption,
VarUseTimeBase = 0.0
;
( VarUseType = var_use_production
; VarUseType = var_use_other
),
VarUseTimeBase = BaseTotalTime
)
),
DepthF = recursion_depth_to_float(Depth),
VarUseTime = VarUseTimeBase +
DepthF * VarUseTimeRec,
Cost = RecTotalTime * probability_to_float(RecProb) +
BaseTotalTime * probability_to_float(not_probability(RecProb)),
MaybeVarUseInfo = ok(var_use_info(VarUseTime, Cost,
VarUseOptions ^ vuo_var_use_type)),
trace [compile_time(flag("debug_first_var_use")),
io(!IO)] (
nl(!IO),
write_string("UseTime = BaseUseTime + " ++
"RecUseTime * Depth\n", !IO),
format("%f = %f + %f * %f\n",
[f(VarUseTime), f(VarUseTimeBase),
f(VarUseTimeRec), f(DepthF)], !IO)
)
;
Info = error(Error),
MaybeVarUseInfo = error(Error)
).
:- type proc_var_first_use_prepared_info
---> error(string)
; proc_var_first_use_prepared_info(
goal_rep(goal_id),
goal_id,
containing_goal_map,
goal_attr_array(coverage_info),
map(reverse_goal_path, cost_and_callees),
map(reverse_goal_path, cs_cost_csq),
var_rep
).
:- pred prepare_for_proc_var_first_use(clique_ptr::in, proc_dynamic_ptr::in,
int::in, recursion_type::in(recursion_type_known_costs),
recursion_depth::in, var_use_options::in,
proc_var_first_use_prepared_info::out) is det.
prepare_for_proc_var_first_use(CliquePtr, PDPtr, ArgNum, RecursionType, Depth,
VarUseOptions, Info) :-
Deep = VarUseOptions ^ vuo_deep,
deep_lookup_proc_dynamics(Deep, PDPtr, PD),
PSPtr = PD ^ pd_proc_static,
deep_get_maybe_procrep(Deep, PSPtr, MaybeProcrep),
(
MaybeProcrep = ok(ProcRep),
ProcDefn = ProcRep ^ pr_defn,
HeadVars = ProcDefn ^ pdr_head_vars,
( index0(HeadVars, ArgNum, head_var_rep(Var, Mode)) ->
var_mode_to_var_use_type(Mode, ComputedUse),
VarUseType = VarUseOptions ^ vuo_var_use_type,
( VarUseType = ComputedUse ->
true
;
PDPtr = proc_dynamic_ptr(PDNum),
string.format(
"Var uses do not match, passed: %s calculated from "
++ "procrep: %s, Arg %d in proc dynamic %d",
[s(string(VarUseType)), s(string(ComputedUse)),
i(ArgNum), i(PDNum)], Msg),
unexpected($module, $pred, Msg)
),
% Prepare callsite information.
proc_dynamic_paired_call_site_slots(Deep, PDPtr, Slots),
foldl(build_dynamic_call_site_cost_and_callee_map(Deep),
Slots, map.init, CallSiteCostMap),
build_recursive_call_site_cost_map(Deep, CliquePtr, PDPtr,
RecursionType, yes(Depth), MaybeRecursiveCallSiteCostMap),
MaybeRecursiveCallSiteCostMap = ok(RecursiveCallSiteCostMap),
% Build procrep
Goal0 = ProcDefn ^ pdr_goal,
label_goals(LastGoalId, ContainingGoalMap, Goal0, Goal),
% Build coverage annotation.
deep_lookup_proc_statics(Deep, PSPtr, PS),
ProcLabel = PS ^ ps_id,
coverage_point_arrays_to_list(PS ^ ps_coverage_point_infos,
CoveragePointsArray, CoveragePoints),
MaybeCoveragePointsArray = PD ^ pd_maybe_coverage_points,
(
MaybeCoveragePointsArray = yes(CoveragePointsArray)
;
MaybeCoveragePointsArray = no,
unexpected($module, $pred, "Couldn't get coverage info")
),
foldl2(add_coverage_point_to_map, CoveragePoints,
map.init, SolnsCoveragePointMap,
map.init, BranchCoveragePointMap),
deep_lookup_pd_own(Deep, PDPtr, Own),
goal_annotate_with_coverage(ProcLabel, Goal, Own, CallSiteCostMap,
SolnsCoveragePointMap, BranchCoveragePointMap,
ContainingGoalMap, LastGoalId, CoverageArray),
Info = proc_var_first_use_prepared_info(Goal, LastGoalId,
ContainingGoalMap, CoverageArray, CallSiteCostMap,
RecursiveCallSiteCostMap, Var)
;
PDPtr = proc_dynamic_ptr(PDNum),
string.format(
"proc_dynamic_var_use_info: ArgNum %d out of range for PD %d",
[i(ArgNum), i(PDNum)], Msg),
Info = error(Msg)
)
;
MaybeProcrep = error(Error),
Info = error(Error)
).
%----------------------------------------------------------------------------%
%
% The actual first use analyais code.
%
% Any changes here should be reflected in the recursion and base case specific
% versions of this code below.
%
% TODO: This code is currently out of date with the code below, corrections
% need to be made to this code, see XXX markers below.
%
% This type represents whether the first use of a variable has been found
% or not. If it has then the call sequence counts since it was found is
% stored in this type also.
%
:- type found_first_use
---> have_not_found_first_use
; found_first_use(
cost_before_use :: float
).
:- inst found_first_use_found
---> found_first_use(ground).
:- type var_first_use_static_info
---> var_first_use_static_info(
fui_clique :: clique_ptr,
fui_call_site_map :: map(reverse_goal_path,
cost_and_callees),
fui_rec_call_site_map :: map(reverse_goal_path,
cs_cost_csq),
fui_containing_goal_map :: containing_goal_map,
fui_coverage_array :: goal_attr_array(coverage_info),
fui_var :: var_rep,
fui_var_use_opts :: var_use_options,
% A set of call sites whose analysis has started but not yet
% completed. We keep this set to prevent infinite recursion
% in the analysis itself.
fui_call_stack :: set(proc_dynamic_ptr),
fui_recursion_type :: recursion_type,
fui_cur_depth :: recursion_depth,
fui_rec_info :: first_use_rec_info
).
:- inst var_first_use_static_info
---> var_first_use_static_info(
ground, ground, ground, ground, ground, ground, ground, ground,
recursion_type_known_costs,
ground, ground
).
:- inst var_first_use_static_info_rec
---> var_first_use_static_info(
ground, ground, ground, ground, ground, ground, ground, ground,
recursion_type_known_costs,
ground,
first_use_rec_info
).
:- type first_use_rec_info
---> first_use_rec_info(
furi_rec_prob_array :: goal_attr_array(probability),
furi_rec_case :: recursive_case
)
; no_recursion_info.
:- inst first_use_rec_info
---> first_use_rec_info(ground, ground).
:- inst no_recursion_info
---> no_recursion_info.
:- type recursive_case
---> recursive_case
; base_case.
% Find the first use of a variable in a goal.
% Procedure calls can be resolved via the call site which we'll need to
% lookup anyway to find cost information, This will callback to the deep
% profiler as it crosses procedure boundaries.
%
% This does not follow higher order or method calls. It may be possible to
% follow call the calls seen during profiling and aggregate their variable
% use information based on how often they are called from that call site.
%
:- pred goal_var_first_use(reverse_goal_path::in, goal_rep(goal_id)::in,
var_first_use_static_info::in(var_first_use_static_info), float::in,
float::out, found_first_use::out) is det.
goal_var_first_use(RevGoalPath, Goal, StaticInfo, !CostSoFar, FoundFirstUse) :-
Goal = goal_rep(GoalExpr, Detism, _),
CoverageArray = StaticInfo ^ fui_coverage_array,
Coverage = get_goal_attribute_det(CoverageArray, Goal ^ goal_annotation),
(
% Do not bother exploring this goal if it is never entered. Or never
% finishes and we're looking for a production.
(
get_coverage_before(Coverage, 0)
;
VarUseType = StaticInfo ^ fui_var_use_opts ^ vuo_var_use_type,
VarUseType = var_use_production,
(
Detism = erroneous_rep
;
Detism = failure_rep
;
get_coverage_after(Coverage, 0)
)
)
->
FoundFirstUse = have_not_found_first_use
;
(
GoalExpr = conj_rep(Conjuncts),
conj_var_first_use(RevGoalPath, 1, Conjuncts, StaticInfo,
!CostSoFar, FoundFirstUse)
;
GoalExpr = disj_rep(Disjuncts),
disj_var_first_use(RevGoalPath, Disjuncts, Detism, StaticInfo,
!CostSoFar, FoundFirstUse)
;
GoalExpr = switch_rep(SwitchedOnVar, _CanFail, Cases),
switch_var_first_use(RevGoalPath, SwitchedOnVar, Cases,
StaticInfo, !CostSoFar, FoundFirstUse)
;
GoalExpr = ite_rep(Cond, Then, Else),
ite_var_first_use(RevGoalPath, Cond, Then, Else, StaticInfo,
!CostSoFar, FoundFirstUse)
;
(
GoalExpr = negation_rep(SubGoal),
GoalPathStep = step_neg
;
GoalExpr = scope_rep(SubGoal, ScopeIsCut),
GoalPathStep = step_scope(ScopeIsCut)
),
RevSubGoalPath = rgp_cons(RevGoalPath, GoalPathStep),
goal_var_first_use(RevSubGoalPath, SubGoal, StaticInfo,
!CostSoFar, FoundFirstUse)
;
GoalExpr = atomic_goal_rep(_, _, BoundVars, AtomicGoal),
(
( AtomicGoal = plain_call_rep(_, _, _)
; AtomicGoal = higher_order_call_rep(_, _)
; AtomicGoal = method_call_rep(_, _, _)
),
call_var_first_use(AtomicGoal, BoundVars, RevGoalPath,
StaticInfo, FoundFirstUse, !CostSoFar)
;
( AtomicGoal = unify_construct_rep(_, _, _)
; AtomicGoal = unify_deconstruct_rep(_, _, _)
; AtomicGoal = partial_construct_rep(_, _, _)
; AtomicGoal = partial_deconstruct_rep(_, _, _)
; AtomicGoal = unify_assign_rep(_, _)
; AtomicGoal = cast_rep(_, _)
; AtomicGoal = unify_simple_test_rep(_, _)
; AtomicGoal = pragma_foreign_code_rep(_)
; AtomicGoal = event_call_rep(_, _)
; AtomicGoal = builtin_call_rep(_, _, _)
),
% trivial goals have a zero cost, so !CostSoFar is not updated.
atomic_trivial_var_first_use(AtomicGoal, BoundVars,
!.CostSoFar, StaticInfo, FoundFirstUse)
)
)
),
trace [compile_time(flag("debug_first_var_use")), io(!IO)] (
io.format("Trace: goal_var_first_use: %s\n",
[s(rev_goal_path_to_string(RevGoalPath))], !IO)
).
:- inst atomic_goal_rep_call
---> plain_call_rep(ground, ground, ground)
; higher_order_call_rep(ground, ground)
; method_call_rep(ground, ground, ground).
:- pred call_var_first_use(atomic_goal_rep::in(atomic_goal_rep_call),
list(var_rep)::in, reverse_goal_path::in,
var_first_use_static_info::in(var_first_use_static_info),
found_first_use::out, float::in, float::out) is det.
call_var_first_use(AtomicGoal, BoundVars, RevGoalPath, StaticInfo,
FoundFirstUse, !CostSoFar) :-
CostBefore = !.CostSoFar,
StaticInfo = var_first_use_static_info(CliquePtr, CostMap,
RecCostMap, _ContainingGoalMap, _CoverageArray, Var, VarUseOptions,
_CallStack, _RecursionType, _MaybeCurDepth, _RecInfo),
VarUseType = VarUseOptions ^ vuo_var_use_type,
map.lookup(CostMap, RevGoalPath, CostAndCallees),
% Get the cost of the call.
( cost_and_callees_is_recursive(CliquePtr, CostAndCallees) ->
map.lookup(RecCostMap, RevGoalPath, Cost0)
;
Cost0 = CostAndCallees ^ cac_cost
),
( cs_cost_get_calls(Cost0) = 0.0 ->
Cost = 0.0
;
Cost = cs_cost_get_percall(Cost0)
),
!:CostSoFar = !.CostSoFar + Cost,
% Determine if the variable we are searching for uses of is involved with
% this call.
(
AtomicGoal = plain_call_rep(_, _, Args),
Vars = Args
;
( AtomicGoal = higher_order_call_rep(HOVar, Args)
; AtomicGoal = method_call_rep(HOVar, _, Args)
),
Vars = [HOVar | Args]
),
( list.member(Var, Vars) ->
solutions((pred(TimeI::out) is nondet :-
(
consume_ho_arg(AtomicGoal, Var, TimeI)
;
call_args_first_use(Args, Cost, StaticInfo,
CostAndCallees, TimeI)
)
), Times),
(
Times = [],
unexpected($module, $pred,
"no solutions for variable first use time")
;
Times = [FirstTime | OtherTimes],
FoundFirstUse = found_first_use(FirstTime + CostBefore),
(
VarUseType = var_use_production
=>
OtherTimes = []
->
true
;
unexpected($module, $pred,
"multiple solutions for variable production time")
)
),
% Assertion
(
VarUseType = var_use_production
=>
list.member(Var, BoundVars)
->
true
;
unexpected($module, $pred,
"a bound var must be produced by a call if it is an argument.")
),
(
VarUseType = var_use_consumption
=>
not member(Var, BoundVars)
->
true
;
unexpected($module, $pred,
"a consumed var must not be mentioned in BoundVars")
),
(
VarUseType = var_use_production
=>
not (
( AtomicGoal = higher_order_call_rep(Var, _)
; AtomicGoal = method_call_rep(Var, _, _)
)
)
->
true
;
unexpected($module, $pred,
"a HO call site cannot produce its own HO value")
)
;
FoundFirstUse = have_not_found_first_use
).
:- pred consume_ho_arg(atomic_goal_rep::in(atomic_goal_rep_call),
var_rep::in, float::out) is semidet.
consume_ho_arg(higher_order_call_rep(Var, _), Var, 0.0).
consume_ho_arg(method_call_rep(Var, _, _), Var, 0.0).
:- pred call_args_first_use(list(var_rep)::in, float::in,
var_first_use_static_info::in(var_first_use_static_info),
cost_and_callees::in, float::out) is nondet.
call_args_first_use(Args, Cost, StaticInfo, CostAndCallees, Time) :-
StaticInfo = var_first_use_static_info(CliquePtr, _CostMap,
_RecCostMap, _ContainingGoalMap, _CoverageArray, Var, VarUseOptions,
CallStack, RecursionType, CurDepth, _RecInfo),
VarUseType = VarUseOptions ^ vuo_var_use_type,
HigherOrder = CostAndCallees ^ cac_call_site_is_ho,
Callees = CostAndCallees ^ cac_callees,
member_index0(Var, Args, ArgNum),
(
HigherOrder = first_order_call,
( empty(Callees) ->
% There are no callees, this code is never called.
pessimistic_var_use_time(VarUseType, Cost, Time)
; is_singleton(Callees, SingletonCallee) ->
CSDPtr = SingletonCallee ^ c_csd,
call_site_dynamic_var_use_info(CliquePtr, CSDPtr,
ArgNum, RecursionType, yes(CurDepth), Cost, CallStack,
VarUseOptions, MaybeVarUseInfo),
(
MaybeVarUseInfo = ok(VarUseInfo),
VarUseInfo = var_use_info(Time, _, _)
;
MaybeVarUseInfo = error(_),
pessimistic_var_use_time(VarUseType, Cost, Time)
)
;
unexpected($module, $pred,
"wrong number of callees for normal call site")
)
;
HigherOrder = higher_order_call,
% The compiler cannot push signals or waits into higher order calls.
% Therefore we assume a pessimistic default here.
pessimistic_var_use_time(VarUseType, Cost, Time)
).
:- inst atomic_trivial_goal_rep
---> unify_construct_rep(ground, ground, ground)
; unify_deconstruct_rep(ground, ground, ground)
; partial_construct_rep(ground, ground, ground)
; partial_deconstruct_rep(ground, ground, ground)
; unify_assign_rep(ground, ground)
; cast_rep(ground, ground)
; unify_simple_test_rep(ground, ground)
; pragma_foreign_code_rep(ground)
; event_call_rep(ground, ground)
; builtin_call_rep(ground, ground, ground).
:- pred atomic_trivial_var_first_use(
atomic_goal_rep::in(atomic_trivial_goal_rep), list(var_rep)::in, float::in,
var_first_use_static_info::in, found_first_use::out) is det.
atomic_trivial_var_first_use(AtomicGoal, BoundVars, CostSoFar, StaticInfo,
FoundFirstUse) :-
Var = StaticInfo ^ fui_var,
VarUseType = StaticInfo ^ fui_var_use_opts ^ vuo_var_use_type,
atomic_goal_get_vars(AtomicGoal, Vars),
(
member(Var, Vars),
(
VarUseType = var_use_consumption
;
VarUseType = var_use_production,
member(Var, BoundVars)
;
VarUseType = var_use_other
)
->
FoundFirstUse = found_first_use(CostSoFar)
;
FoundFirstUse = have_not_found_first_use
).
% Find the first use of a variable within a conjunction. Note that when
% looking for a production of the variable we search backward and add the
% time from the end of the goal. Similarly with other goal types that have
% an execution order, namely disjunctions and if-then-elses.
%
:- pred conj_var_first_use(reverse_goal_path::in, int::in,
list(goal_rep(goal_id))::in,
var_first_use_static_info::in(var_first_use_static_info),
float::in, float::out, found_first_use::out) is det.
conj_var_first_use(_, _, [], _, !Cost, have_not_found_first_use).
conj_var_first_use(RevGoalPath, ConjNum, [Conj | Conjs], StaticInfo,
!CostSoFar, FoundFirstUse) :-
goal_var_first_use(rgp_cons(RevGoalPath, step_conj(ConjNum)), Conj,
StaticInfo, !CostSoFar, HeadFoundFirstUse),
(
% If a variable is bound more than once, then we want to use
% the last time it is bound, since all of the earlier bindings
% must have only partially instantiated it. Instmaps can be used
% to track this. This is relevant when searching for the producer
% of a variable.
% XXX: For now, we assume that no variable is bound more than once.
HeadFoundFirstUse = found_first_use(_),
FoundFirstUse = HeadFoundFirstUse
;
HeadFoundFirstUse = have_not_found_first_use,
conj_var_first_use(RevGoalPath, ConjNum + 1, Conjs, StaticInfo,
!CostSoFar, TailFoundFirstUse),
FoundFirstUse = TailFoundFirstUse
).
:- pred disj_var_first_use(reverse_goal_path::in,
list(goal_rep(goal_id))::in, detism_rep::in,
var_first_use_static_info::in(var_first_use_static_info),
float::in, float::out, found_first_use::out) is det.
disj_var_first_use(RevGoalPath, Disjuncts, Detism, StaticInfo,
!CostSoFar, FoundFirstUse) :-
% We cannot handle nondet/multi disjunctions. So we use pessimistic
% defaults for FoundFirstUse if this disjunction is nondet or multi.
% For calculating the cost of the disjunction, assume that is is a semidet
% disjunction. Doing this will find the incorrect cost for the
% disjunction. However disjunctions occur rarely, so this is not likely
% to dramatically affect anything.
CostBeforeDisjunction = !.CostSoFar,
disj_var_first_use_2(RevGoalPath, 1, Disjuncts, StaticInfo,
!CostSoFar, FoundFirstUse0),
CostAfterDisjunction = !.CostSoFar,
(
detism_get_solutions(Detism) = at_most_many_rep,