%-----------------------------------------------------------------------------% % vim: ft=mercury ts=4 sw=4 et %-----------------------------------------------------------------------------% % Copyright (C) 2005-2007 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: trailing_analysis.m. % Author: juliensf. % % This module implements trail usage analysis. It annotates the HLDS with % information about which procedures will not modify the trail. % % The compiler can use this information to omit redundant trailing operations % in trailing grades. After running the analysis the trailing status of each % procedure is one of: % % (1) trail_will_not_modify % (2) trail_may_modify % (3) trail_conditional % % These have the following meaning: % % (1) for all inputs the procedure will not modify the trail. % (2) for some inputs the procedure may modify the trail. % (3) the procedure is polymorphic and whether it may modify the trail % depends upon the instantiation of the type variables. We need % this because we can define types with user-defined equality or % comparison that modify the trail. % % NOTE: to be `trail_conditional' a procedure cannot modify the trail itself, % any trail modifications that occur through the conditional procedure % must result from a higher-order call or a call to a user-defined equality % or comparison predicate. % % For procedures defined using the foreign language interface we rely upon % the user annotations `will_not_modify_trail' and `may_not_modify_trail'. % % The predicates for determining if individual goals modify the trail % are in goal_form.m. % % TODO: % % - Use the results of closure analysis to determine the trailing % status of higher-order calls. % - Improve the analysis in the presence of solver types. % - Create specialised versions of higher-order procedures based on % whether or not their arguments modify the trail. % %----------------------------------------------------------------------------% :- module transform_hlds.trailing_analysis. :- interface. :- import_module analysis. :- import_module hlds.hlds_module. :- import_module hlds.hlds_pred. :- import_module io. %----------------------------------------------------------------------------% % Perform trail usage analysis on a module. % :- pred analyse_trail_usage(module_info::in, module_info::out, io::di, io::uo) is det. % Write out the trailing_info pragma for this module. % :- pred write_pragma_trailing_info(module_info::in, trailing_info::in, pred_id::in, io::di, io::uo) is det. % Types and instances for the intermodule analysis framework. % :- type trailing_analysis_answer. :- instance analysis(any_call, trailing_analysis_answer). :- instance partial_order(trailing_analysis_answer). :- instance answer_pattern(trailing_analysis_answer). :- instance to_string(trailing_analysis_answer). %----------------------------------------------------------------------------% %----------------------------------------------------------------------------% :- implementation. :- import_module check_hlds.type_util. :- import_module hlds.code_model. :- import_module hlds.hlds_error_util. :- import_module hlds.hlds_goal. :- import_module hlds.hlds_pred. :- import_module libs.compiler_util. :- import_module libs.globals. :- import_module libs.options. :- import_module mdbcomp.prim_data. :- import_module parse_tree.error_util. :- import_module parse_tree.mercury_to_mercury. :- import_module parse_tree.modules. :- import_module parse_tree.prog_data. :- import_module parse_tree.prog_out. :- import_module parse_tree.prog_type. :- import_module transform_hlds.dependency_graph. :- import_module transform_hlds.mmc_analysis. :- import_module bool. :- import_module list. :- import_module map. :- import_module maybe. :- import_module pair. :- import_module set. :- import_module string. :- import_module term. %----------------------------------------------------------------------------% % % Perform trail usage analysis on a module % % The analysis is carried out in two passes. Both passes do a bottom-up % traversal of the callgraph, one SCC at a time. For each SCC the first % pass works out the trailing_status for each procedure in the SCC. The % second pass then uses this information to annotate the goals in each % procedure with trail usage information. % % The second pass is only run if we are going to use the information, % that is if we are generating code as opposed to building the optimization % interfaces. analyse_trail_usage(!ModuleInfo, !IO) :- globals.io_lookup_bool_option(use_trail, UseTrail, !IO), ( % Only run the analysis in trailing grades. UseTrail = yes, globals.io_lookup_bool_option(make_optimization_interface, MakeOptInt, !IO), globals.io_lookup_bool_option(make_transitive_opt_interface, MakeTransOptInt, !IO), globals.io_lookup_bool_option(make_analysis_registry, MakeAnalysisReg, !IO), Pass1Only = MakeOptInt `bool.or` MakeTransOptInt `bool.or` MakeAnalysisReg, module_info_ensure_dependency_info(!ModuleInfo), module_info_dependency_info(!.ModuleInfo, DepInfo), hlds_dependency_info_get_dependency_ordering(DepInfo, SCCs), globals.io_lookup_bool_option(debug_trail_usage, Debug, !IO), list.foldl2(process_scc(Debug, Pass1Only), SCCs, !ModuleInfo, !IO), ( MakeOptInt = yes, make_opt_int(!.ModuleInfo, !IO) ; MakeOptInt = no ) ; UseTrail = no ). %----------------------------------------------------------------------------% % % Perform trail usage analysis on a SCC % :- type scc == list(pred_proc_id). :- type proc_results == list(proc_result). :- type proc_result ---> proc_result( ppid :: pred_proc_id, status :: trailing_status, maybe_analysis_status :: maybe(analysis_status) ). :- pred process_scc(bool::in, bool::in, scc::in, module_info::in, module_info::out, io::di, io::uo) is det. process_scc(Debug, Pass1Only, SCC, !ModuleInfo, !IO) :- check_procs_for_trail_mods(SCC, ProcResults, !ModuleInfo, !IO), % % The `Results' above are the results of analysing each individual % procedure in the SCC - we now have to combine them in a meaningful way. % combine_individual_proc_results(ProcResults, TrailingStatus, MaybeAnalysisStatus), % % Print out debugging information. % ( Debug = yes, dump_trail_usage_debug_info(!.ModuleInfo, SCC, TrailingStatus, !IO) ; Debug = no ), % % Update the trailing_info with information about this SCC. % module_info_get_trailing_info(!.ModuleInfo, TrailingInfo0), Update = (pred(PPId::in, Info0::in, Info::out) is det :- Info = Info0 ^ elem(PPId) := proc_trailing_info(TrailingStatus, MaybeAnalysisStatus) ), list.foldl(Update, SCC, TrailingInfo0, TrailingInfo), module_info_set_trailing_info(TrailingInfo, !ModuleInfo), % % Record the analysis results for the intermodule analysis % globals.io_lookup_bool_option(make_analysis_registry, MakeAnalysisRegistry, !IO), ( MakeAnalysisRegistry = yes, ( MaybeAnalysisStatus = yes(AnalysisStatus), record_trailing_analysis_results(TrailingStatus, AnalysisStatus, SCC, !ModuleInfo) ; MaybeAnalysisStatus = no, unexpected(this_file, "process_scc: no analysis status") ) ; MakeAnalysisRegistry = no ), ( Pass1Only = no, list.foldl2(annotate_proc, SCC, !ModuleInfo, !IO) ; Pass1Only = yes ). % Check each procedure in the SCC individually. % :- pred check_procs_for_trail_mods(scc::in, proc_results::out, module_info::in, module_info::out, io::di, io::uo) is det. check_procs_for_trail_mods(SCC, Result, !ModuleInfo, !IO) :- list.foldl3(check_proc_for_trail_mods(SCC), SCC, [], Result, !ModuleInfo, !IO). % Examine how the procedures interact with other procedures that % are mutually-recursive to them. % :- pred combine_individual_proc_results(proc_results::in, trailing_status::out, maybe(analysis_status)::out) is det. combine_individual_proc_results([], _, _) :- unexpected(this_file, "Empty SCC during trailing analysis."). combine_individual_proc_results(ProcResults @ [_|_], SCC_Result, MaybeAnalysisStatus) :- ( % If none of the procedures modifies the trail or is conditional then % the SCC cannot modify the trail. all [ProcResult] list.member(ProcResult, ProcResults) => ProcResult ^ status = trail_will_not_modify -> SCC_Result = trail_will_not_modify ; all [EResult] list.member(EResult, ProcResults) => EResult ^ status \= trail_may_modify, some [CResult] ( list.member(CResult, ProcResults), CResult ^ status = trail_conditional ) -> SCC_Result = trail_conditional ; % Otherwise the SCC may modify the trail. SCC_Result = trail_may_modify ), combine_proc_result_maybe_analysis_statuses(ProcResults, MaybeAnalysisStatus). :- pred combine_proc_result_maybe_analysis_statuses(proc_results::in, maybe(analysis_status)::out) is det. combine_proc_result_maybe_analysis_statuses(ProcResults, MaybeAnalysisStatus) :- list.map(maybe_analysis_status, ProcResults, MaybeAnalysisStatuses), list.foldl(combine_maybe_analysis_status, MaybeAnalysisStatuses, yes(optimal), MaybeAnalysisStatus). :- pred maybe_analysis_status(proc_result::in, maybe(analysis_status)::out) is det. maybe_analysis_status(ProcResult, ProcResult ^ maybe_analysis_status). %----------------------------------------------------------------------------% % % Perform trail usage analysis on a procedure % :- pred check_proc_for_trail_mods(scc::in, pred_proc_id::in, proc_results::in, proc_results::out, module_info::in, module_info::out, io::di, io::uo) is det. check_proc_for_trail_mods(SCC, PPId, !Results, !ModuleInfo, !IO) :- module_info_pred_proc_info(!.ModuleInfo, PPId, _, ProcInfo), proc_info_get_goal(ProcInfo, Body), proc_info_get_vartypes(ProcInfo, VarTypes), check_goal_for_trail_mods(SCC, VarTypes, Body, Result, MaybeAnalysisStatus, !ModuleInfo, !IO), list.cons(proc_result(PPId, Result, MaybeAnalysisStatus), !Results). %----------------------------------------------------------------------------% % % Perform trail usage analysis of a goal % :- pred check_goal_for_trail_mods(scc::in, vartypes::in, hlds_goal::in, trailing_status::out, maybe(analysis_status)::out, module_info::in, module_info::out, io::di, io::uo) is det. check_goal_for_trail_mods(SCC, VarTypes, hlds_goal(GoalExpr, GoalInfo), Result, MaybeStatus, !ModuleInfo, !IO) :- check_goal_for_trail_mods_2(SCC, VarTypes, GoalExpr, GoalInfo, Result, MaybeStatus, !ModuleInfo, !IO). :- pred check_goal_for_trail_mods_2(scc::in, vartypes::in, hlds_goal_expr::in, hlds_goal_info::in, trailing_status::out, maybe(analysis_status)::out, module_info::in, module_info::out, io::di, io::uo) is det. check_goal_for_trail_mods_2(_, _, GoalExpr, _, trail_will_not_modify, yes(optimal), !ModuleInfo, !IO) :- GoalExpr = unify(_, _, _, Kind, _), ( ( Kind = construct(_, _, _, _, _, _, _) ; Kind = deconstruct(_, _, _, _, _, _) ; Kind = assign(_, _) ; Kind = simple_test(_, _) ) ; Kind = complicated_unify(_, _, _), unexpected(this_file, "complicated unify during trail usage analysis.") ). check_goal_for_trail_mods_2(SCC, VarTypes, GoalExpr, _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- GoalExpr = plain_call(CallPredId, CallProcId, CallArgs, _, _, _), CallPPId = proc(CallPredId, CallProcId), module_info_pred_info(!.ModuleInfo, CallPredId, CallPredInfo), ( % Handle (mutually-)recursive calls. list.member(CallPPId, SCC) -> Types = list.map((func(Var) = VarTypes ^ det_elem(Var)), CallArgs), TrailingStatus = check_types(!.ModuleInfo, Types), Result = TrailingStatus, MaybeAnalysisStatus = yes(optimal) ; pred_info_is_builtin(CallPredInfo) -> % There are no builtins that will modify the trail. Result = trail_will_not_modify, MaybeAnalysisStatus = yes(optimal) ; % Handle builtin unify and compare. % NOTE: the type specific unify and compare predicates are just % treated as though they were normal predicates. ModuleName = pred_info_module(CallPredInfo), any_mercury_builtin_module(ModuleName), Name = pred_info_name(CallPredInfo), Arity = pred_info_orig_arity(CallPredInfo), ( SpecialPredId = spec_pred_compare ; SpecialPredId = spec_pred_unify ), special_pred_name_arity(SpecialPredId, Name, _, Arity) -> % XXX We should examine the argument types of calls to builtin.unify/2 % and builtin.compare/3 and then make a decision based on those. Result = trail_may_modify, MaybeAnalysisStatus = yes(optimal) ; % Handle library predicates whose trailing status % can be looked up in the known procedures table. pred_info_has_known_status(CallPredInfo, Result0) -> Result = Result0, MaybeAnalysisStatus = yes(optimal) ; globals.io_lookup_bool_option(intermodule_analysis, Intermod, !IO), ( Intermod = yes, pred_info_is_imported(CallPredInfo) -> % With --intermodule-analysis use check_call_2 to look up results % for locally defined procedures, otherwise we use the intermodule % analysis framework. search_analysis_status(CallPPId, Result0, AnalysisStatus, SCC, !ModuleInfo, !IO), ( Result0 = trail_conditional, Result = check_vars(!.ModuleInfo, VarTypes, CallArgs) ; ( Result0 = trail_may_modify ; Result0 = trail_will_not_modify ), Result = Result0 ), MaybeAnalysisStatus = yes(AnalysisStatus) ; check_call_2(!.ModuleInfo, VarTypes, CallPPId, CallArgs, MaybeResult), ( MaybeResult = yes(proc_trailing_info(Result, MaybeAnalysisStatus)) ; MaybeResult = no, % If we do not have any information about the callee procedure % then assume that it modifies the trail. Result = trail_may_modify, ( Intermod = yes, MaybeAnalysisStatus = yes(suboptimal) ; Intermod = no, MaybeAnalysisStatus = no ) ) ) ). check_goal_for_trail_mods_2(_, _VarTypes, GoalExpr, _GoalInfo, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- GoalExpr = generic_call(Details, _Args, _ArgModes, _), ( % XXX Use results of closure analysis to handle this. Details = higher_order(_Var, _, _, _), Result = trail_may_modify, MaybeAnalysisStatus = yes(optimal) ; % XXX We could do better with class methods. Details = class_method(_, _, _, _), Result = trail_may_modify, MaybeAnalysisStatus = yes(optimal) ; ( Details = cast(_) ; Details = event_call(_) ), Result = trail_will_not_modify, MaybeAnalysisStatus = yes(optimal) ). check_goal_for_trail_mods_2(SCC, VarTypes, negation(Goal), _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- check_goal_for_trail_mods(SCC, VarTypes, Goal, Result, MaybeAnalysisStatus, !ModuleInfo, !IO). check_goal_for_trail_mods_2(SCC, VarTypes, GoalExpr, OuterGoalInfo, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- GoalExpr = scope(_, InnerGoal), check_goal_for_trail_mods(SCC, VarTypes, InnerGoal, Result0, MaybeAnalysisStatus, !ModuleInfo, !IO), InnerGoal = hlds_goal(_, InnerGoalInfo), InnerCodeModel = goal_info_get_code_model(InnerGoalInfo), OuterCodeModel = goal_info_get_code_model(OuterGoalInfo), % % `trail_conditional' scope goals (of the type that require extra trailing % code) will have there status changed to `trail_may_modify'. % See the comment in the clause that handles if-then-elses below % for the reason why. % Result = scope_implies_trail_mod(InnerCodeModel, OuterCodeModel, Result0). check_goal_for_trail_mods_2(_, _, GoalExpr, _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- GoalExpr = call_foreign_proc(Attributes, _, _, _, _, _, _), Result = attributes_imply_trail_mod(Attributes), MaybeAnalysisStatus = yes(optimal). check_goal_for_trail_mods_2(_, _, shorthand(_), _, _, _, !ModuleInfo, !IO) :- unexpected(this_file, "shorthand goal encountered during trail usage analysis."). check_goal_for_trail_mods_2(SCC, VarTypes, GoalExpr, _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- GoalExpr = switch(_, _, Cases), CaseGoals = list.map((func(case(_, CaseGoal)) = CaseGoal), Cases), check_goals_for_trail_mods(SCC, VarTypes, CaseGoals, Result, MaybeAnalysisStatus, !ModuleInfo, !IO). check_goal_for_trail_mods_2(SCC, VarTypes, GoalExpr, _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- GoalExpr = if_then_else(_, Cond, Then, Else), check_goals_for_trail_mods(SCC, VarTypes, [Cond, Then, Else], Result0, MaybeAnalysisStatus, !ModuleInfo, !IO), ( % If the condition of an if-then-else does not modify the trail % and is not model_non then we can omit the trailing ops around % the condition. % % NOTE: any changes here may need to be relected in the clause % of add_trail_ops.goal_expr_add_trail_ops that handles if_then_elses. % Result0 = trail_will_not_modify, Cond = hlds_goal(_CondGoalExpr, CondGoalInfo), goal_info_get_code_model(CondGoalInfo) \= model_non -> Result = trail_will_not_modify ; % If the condition modifies the trail, is model_non or both then % we need to emit trailing ops around the conditoin. If the % if-then-else has status `trail_conditional' then we also need % to emit the trail ops because we cannot be sure that calls to % builtin.{unify,compare} won't call user-defined equality or % comparison predicates that modify the trail. % % NOTE: conditional procedures whose status is changed here are % candidates for generating specialized versions that omit % the trailing code. % Result = trail_may_modify ). check_goal_for_trail_mods_2(SCC, VarTypes, conj(_, Goals), _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- check_goals_for_trail_mods(SCC, VarTypes, Goals, Result, MaybeAnalysisStatus, !ModuleInfo, !IO). check_goal_for_trail_mods_2(SCC, VarTypes, disj(Goals), _, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- check_goals_for_trail_mods(SCC, VarTypes, Goals, _Result0, MaybeAnalysisStatus, !ModuleInfo, !IO), % XXX Currently we have to put trailing code around disjunctions. % If we introduce trail specialisation it may be possible to % omit it. Result = trail_may_modify. :- pred check_goals_for_trail_mods(scc::in, vartypes::in, hlds_goals::in, trailing_status::out, maybe(analysis_status)::out, module_info::in, module_info::out, io::di, io::uo) is det. check_goals_for_trail_mods(SCC, VarTypes, Goals, Result, MaybeAnalysisStatus, !ModuleInfo, !IO) :- list.map2_foldl2(check_goal_for_trail_mods(SCC, VarTypes), Goals, Results, MaybeAnalysisStatuses, !ModuleInfo, !IO), list.foldl(combine_trailing_status, Results, trail_will_not_modify, Result), list.foldl(combine_maybe_analysis_status, MaybeAnalysisStatuses, yes(optimal), MaybeAnalysisStatus). %----------------------------------------------------------------------------% % % Utility procedure for processing goals % :- func attributes_imply_trail_mod(pragma_foreign_proc_attributes) = trailing_status. attributes_imply_trail_mod(Attributes) = ( get_may_modify_trail(Attributes) = proc_may_modify_trail -> trail_may_modify ; trail_will_not_modify ). :- func scope_implies_trail_mod(code_model, code_model, trailing_status) = trailing_status. scope_implies_trail_mod(InnerCodeModel, OuterCodeModel, InnerStatus) = ( % If we're at a commit for a goal that might modify the trail % then we need to emit some trailing code around the scope goal. InnerCodeModel = model_non, OuterCodeModel \= model_non -> trail_may_modify ; InnerStatus ). %----------------------------------------------------------------------------% % % "Known" library procedures % % Succeeds if the given pred_info is for a predicate or function % whose trailing status can be looked up in the known procedures % table. Returns the trailing status corresponding to that procedure. % Fails if there was no corresponding entry in the table. % :- pred pred_info_has_known_status(pred_info::in, trailing_status::out) is semidet. pred_info_has_known_status(PredInfo, Status) :- Name = pred_info_name(PredInfo), PredOrFunc = pred_info_is_pred_or_func(PredInfo), ModuleName = pred_info_module(PredInfo), ModuleName = unqualified(ModuleNameStr), Arity = pred_info_orig_arity(PredInfo), known_procedure(PredOrFunc, ModuleNameStr, Name, Arity, Status). % known_procedure/4 is a table of library predicates whose trailing % status is hardcoded into the analyser. For a few predicates this % information can make a big difference (particularly in the absence % of any form of intermodule analysis). % :- pred known_procedure(pred_or_func::in, string::in, string::in, int::in, trailing_status::out) is semidet. known_procedure(pf_predicate, "require", "error", 1, trail_will_not_modify). known_procedure(pf_function, "require", "func_error", 1, trail_will_not_modify). known_procedure(_, "exception", "throw", 1, trail_will_not_modify). known_procedure(_, "exception", "rethrow", 1, trail_will_not_modify). %----------------------------------------------------------------------------% % % Further code to handle higher-order variables % % Extract those procedures whose trailing_status has been set to % `conditional'. Fails if one of the procedures in the set % is known to modify the trail or if the trailing status is not % yet been set for one or more of the procedures. % % XXX The latter case probably shouldn't happen but may at the % moment because the construction of the dependency graph doesn't % take higher-order calls into account. % :- pred get_conditional_closures(module_info::in, set(pred_proc_id)::in, list(pred_proc_id)::out) is semidet. get_conditional_closures(ModuleInfo, Closures, Conditionals) :- module_info_get_trailing_info(ModuleInfo, TrailingInfo), set.fold(get_conditional_closure(TrailingInfo), Closures, [], Conditionals). :- pred get_conditional_closure(trailing_info::in, pred_proc_id::in, list(pred_proc_id)::in, list(pred_proc_id)::out) is semidet. get_conditional_closure(TrailingInfo, PPId, !Conditionals) :- TrailingInfo ^ elem(PPId) = proc_trailing_info(Status, _), ( Status = trail_conditional, list.cons(PPId, !Conditionals) ; Status = trail_will_not_modify ). %----------------------------------------------------------------------------% :- pred combine_trailing_status(trailing_status::in, trailing_status::in, trailing_status::out) is det. combine_trailing_status(trail_will_not_modify, Y, Y). combine_trailing_status(trail_may_modify, _, trail_may_modify). combine_trailing_status(trail_conditional, trail_will_not_modify, trail_conditional). combine_trailing_status(trail_conditional, trail_conditional, trail_conditional). combine_trailing_status(trail_conditional, trail_may_modify, trail_may_modify). :- pred combine_maybe_analysis_status(maybe(analysis_status)::in, maybe(analysis_status)::in, maybe(analysis_status)::out) is det. combine_maybe_analysis_status(MaybeStatusA, MaybeStatusB, MaybeStatus) :- ( MaybeStatusA = yes(StatusA), MaybeStatusB = yes(StatusB) -> MaybeStatus = yes(analysis.lub(StatusA, StatusB)) ; MaybeStatus = no ). %----------------------------------------------------------------------------% % % Extra procedures for handling calls % % Check the trailing status of a call. % :- pred check_call(module_info::in, vartypes::in, pred_proc_id::in, prog_vars::in, trailing_status::out) is det. check_call(ModuleInfo, VarTypes, PPId, Args, Result) :- check_call_2(ModuleInfo, VarTypes, PPId, Args, MaybeResult), ( MaybeResult = yes(proc_trailing_info(Result, _)) ; MaybeResult = no, % If we do not have any information about the callee procedure then % assume that it modifies the trail. Result = trail_may_modify ). :- pred check_call_2(module_info::in, vartypes::in, pred_proc_id::in, prog_vars::in, maybe(proc_trailing_info)::out) is det. check_call_2(ModuleInfo, VarTypes, PPId, Args, MaybeResult) :- module_info_get_trailing_info(ModuleInfo, TrailingInfo), ( map.search(TrailingInfo, PPId, CalleeTrailingInfo) -> CalleeTrailingInfo = proc_trailing_info(CalleeTrailingStatus, AnalysisStatus), ( CalleeTrailingStatus = trail_will_not_modify, MaybeResult = yes(CalleeTrailingInfo) ; CalleeTrailingStatus = trail_may_modify, MaybeResult = yes(CalleeTrailingInfo) ; CalleeTrailingStatus = trail_conditional, % % This is a call to a polymorphic procedure. We need to make % sure that none of the types involved has a user-defined % equality or comparison predicate that modifies the trail. % XXX Need to handle higher-order args here as well. MaybeResult = yes(proc_trailing_info(TrailingStatus, AnalysisStatus)), TrailingStatus = check_vars(ModuleInfo, VarTypes, Args) ) ; MaybeResult = no ). :- func check_vars(module_info, vartypes, prog_vars) = trailing_status. check_vars(ModuleInfo, VarTypes, Vars) = Result :- Types = list.map((func(Var) = VarTypes ^ det_elem(Var)), Vars), Result = check_types(ModuleInfo, Types). %----------------------------------------------------------------------------% % % Stuff for processing types % % This is used in the analysis of calls to polymorphic procedures. % % By saying that a "type may modify the trail" we mean that tail modification % may occur as a result of a unification or comparison involving the type % because it has a user-defined equality/comparison predicate that modifies % the trail. % % XXX We don't actually need to examine all the types, just those % that are potentially going to be involved in unification/comparisons. % (The exception and termination analyses have the same problem.) % % At the moment we don't keep track of that information so the current % procedure is as follows: % % Examine the functor and then recursively examine the arguments. % % * If everything will not trail_will_not_modify then the type will not % modify the trail. % % * If at least one of the types may modify the trail then the type will % will modify the trail. % % * If at least one of the types is conditional and none of them modify % the trail then the type is conditional. % Return the collective trailing status of a list of types. % :- func check_types(module_info, list(mer_type)) = trailing_status. check_types(ModuleInfo, Types) = Status :- list.foldl(check_type(ModuleInfo), Types, trail_will_not_modify, Status). :- pred check_type(module_info::in, mer_type::in, trailing_status::in, trailing_status::out) is det. check_type(ModuleInfo, Type, !Status) :- combine_trailing_status(check_type(ModuleInfo, Type), !Status). % Return the trailing status of an individual type. % :- func check_type(module_info, mer_type) = trailing_status. check_type(ModuleInfo, Type) = Status :- ( ( is_solver_type(ModuleInfo, Type) ; is_existq_type(ModuleInfo, Type)) -> % XXX At the moment we just assume that existential % types and solver types may modify the trail. Status = trail_may_modify ; TypeCategory = classify_type(ModuleInfo, Type), Status = check_type_2(ModuleInfo, Type, TypeCategory) ). :- func check_type_2(module_info, mer_type, type_category) = trailing_status. check_type_2(_, _, type_cat_int) = trail_will_not_modify. check_type_2(_, _, type_cat_char) = trail_will_not_modify. check_type_2(_, _, type_cat_string) = trail_will_not_modify. check_type_2(_, _, type_cat_float) = trail_will_not_modify. check_type_2(_, _, type_cat_higher_order) = trail_will_not_modify. check_type_2(_, _, type_cat_type_info) = trail_will_not_modify. check_type_2(_, _, type_cat_type_ctor_info) = trail_will_not_modify. check_type_2(_, _, type_cat_typeclass_info) = trail_will_not_modify. check_type_2(_, _, type_cat_base_typeclass_info) = trail_will_not_modify. check_type_2(_, _, type_cat_void) = trail_will_not_modify. check_type_2(_, _, type_cat_dummy) = trail_will_not_modify. check_type_2(_, _, type_cat_variable) = trail_conditional. check_type_2(ModuleInfo, Type, type_cat_tuple) = check_user_type(ModuleInfo, Type). check_type_2(ModuleInfo, Type, type_cat_enum) = check_user_type(ModuleInfo, Type). check_type_2(ModuleInfo, Type, type_cat_foreign_enum) = check_user_type(ModuleInfo, Type). check_type_2(ModuleInfo, Type, type_cat_user_ctor) = check_user_type(ModuleInfo, Type). :- func check_user_type(module_info, mer_type) = trailing_status. check_user_type(ModuleInfo, Type) = Status :- ( type_to_ctor_and_args(Type, _TypeCtor, Args) -> ( type_has_user_defined_equality_pred(ModuleInfo, Type, _UnifyCompare) -> % XXX We can do better than this by examining % what these preds actually do. Something % similar needs to be sorted out for termination % analysis as well, so we'll wait until that is % done. Status = trail_may_modify ; Status = check_types(ModuleInfo, Args) ) ; unexpected(this_file, "Unable to get ctor and args.") ). %----------------------------------------------------------------------------% % % Code for attaching trail usage information to goals % % Traverse the body of the procedure and attach will_not_modify trail % features to the goal_infos of those procedure that cannot modify the % trail. % :- pred annotate_proc(pred_proc_id::in, module_info::in, module_info::out, io::di, io::uo) is det. annotate_proc(PPId, !ModuleInfo, !IO) :- some [!ProcInfo, !Body] ( module_info_pred_proc_info(!.ModuleInfo, PPId, PredInfo, !:ProcInfo), proc_info_get_goal(!.ProcInfo, !:Body), proc_info_get_vartypes(!.ProcInfo, VarTypes), annotate_goal(VarTypes, !Body, _Status, !ModuleInfo, !IO), proc_info_set_goal(!.Body, !ProcInfo), module_info_set_pred_proc_info(PPId, PredInfo, !.ProcInfo, !ModuleInfo) ). :- pred annotate_goal(vartypes::in, hlds_goal::in, hlds_goal::out, trailing_status::out, module_info::in, module_info::out, io::di, io::uo) is det. annotate_goal(VarTypes, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = hlds_goal(GoalExpr0, GoalInfo0), annotate_goal_2(VarTypes, GoalInfo0, GoalExpr0, GoalExpr, Status, !ModuleInfo, !IO), ( Status = trail_will_not_modify, goal_info_add_feature(feature_will_not_modify_trail, GoalInfo0, GoalInfo) ; ( Status = trail_may_modify ; Status = trail_conditional ), GoalInfo = GoalInfo0 ), !:Goal = hlds_goal(GoalExpr, GoalInfo). :- pred annotate_goal_2(vartypes::in, hlds_goal_info::in, hlds_goal_expr::in, hlds_goal_expr::out, trailing_status::out, module_info::in, module_info::out, io::di, io::uo) is det. annotate_goal_2(VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = conj(ConjType, Conjuncts0), annotate_goal_list(VarTypes, Conjuncts0, Conjuncts, Status, !ModuleInfo, !IO), !:Goal = conj(ConjType, Conjuncts). annotate_goal_2(VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = plain_call(CallPredId, CallProcId, CallArgs, _, _, _), CallPPId = proc(CallPredId, CallProcId), module_info_pred_info(!.ModuleInfo, CallPredId, CallPredInfo), ( pred_info_is_builtin(CallPredInfo) -> Status = trail_will_not_modify ; % Handle builtin unify and compare. ModuleName = pred_info_module(CallPredInfo), any_mercury_builtin_module(ModuleName), Name = pred_info_name(CallPredInfo), Arity = pred_info_orig_arity(CallPredInfo), ( SpecialPredId = spec_pred_compare ; SpecialPredId = spec_pred_unify ), special_pred_name_arity(SpecialPredId, Name, _, Arity) -> Status = trail_may_modify ; % Handle library predicates whose trailing status % can be looked up in the known procedure table. pred_info_has_known_status(CallPredInfo, Status0) -> Status = Status0 ; globals.io_lookup_bool_option(intermodule_analysis, IntermodAnalysis, !IO), ( IntermodAnalysis = yes, pred_info_is_imported(CallPredInfo) -> % NOTE: we set the value of SCC to a dummy value here. This is OK % because it only needs a meaningful value when building the % analysis files; it won't be used when compiling to target code. SCC = [], search_analysis_status(CallPPId, Result, AnalysisStatus, SCC, !ModuleInfo, !IO), % XXX We shouldn't be getting invalid analysis results at this % stage so maybe we should just call unexpected/2 here? ( AnalysisStatus = invalid, Status = trail_may_modify ; ( AnalysisStatus = suboptimal ; AnalysisStatus = optimal ), ( Result = trail_conditional, Status = check_vars(!.ModuleInfo, VarTypes, CallArgs) ; ( Result = trail_may_modify ; Result = trail_will_not_modify ), Status = Result ) ) ; % This time around we will be checking recursive calls as well. check_call(!.ModuleInfo, VarTypes, CallPPId, CallArgs, Status) ) ). annotate_goal_2(_VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- % XXX Use closure analysis results here. !.Goal = generic_call(Details, _, _, _), ( Details = higher_order(_, _, _, _), Status = trail_may_modify ; Details = class_method(_, _, _, _), Status = trail_may_modify ; Details = event_call(_), Status = trail_will_not_modify ; Details = cast(_), Status = trail_will_not_modify ). annotate_goal_2(VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = switch(Var, CanFail, Cases0), annotate_cases(VarTypes, Cases0, Cases, Status, !ModuleInfo, !IO), !:Goal = switch(Var, CanFail, Cases). annotate_goal_2(_VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = unify(_, _, _, Kind, _), ( ( Kind = construct(_, _, _, _, _, _, _) ; Kind = deconstruct(_, _, _, _, _, _) ; Kind = assign(_, _) ; Kind = simple_test(_, _) ) ; Kind = complicated_unify(_, _, _), unexpected(this_file, "complicated unify during trail usage analysis.") ), Status = trail_will_not_modify. annotate_goal_2(VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = disj(Disjuncts0), annotate_goal_list(VarTypes, Disjuncts0, Disjuncts, Status, !ModuleInfo, !IO), !:Goal = disj(Disjuncts). annotate_goal_2(VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = negation(NegGoal0), annotate_goal(VarTypes, NegGoal0, NegGoal, Status, !ModuleInfo, !IO), !:Goal = negation(NegGoal). annotate_goal_2(VarTypes, OuterGoalInfo, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = scope(Reason, InnerGoal0), annotate_goal(VarTypes, InnerGoal0, InnerGoal, Status0, !ModuleInfo, !IO), InnerGoal = hlds_goal(_, InnerGoalInfo), InnerCodeModel = goal_info_get_code_model(InnerGoalInfo), OuterCodeModel = goal_info_get_code_model(OuterGoalInfo), Status = scope_implies_trail_mod(InnerCodeModel, OuterCodeModel, Status0), !:Goal = scope(Reason, InnerGoal). annotate_goal_2(VarTypes, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = if_then_else(Vars, If0, Then0, Else0), annotate_goal(VarTypes, If0, If, IfStatus, !ModuleInfo, !IO), annotate_goal(VarTypes, Then0, Then, ThenStatus, !ModuleInfo, !IO), annotate_goal(VarTypes, Else0, Else, ElseStatus, !ModuleInfo, !IO), ( IfStatus = trail_will_not_modify, ThenStatus = trail_will_not_modify, ElseStatus = trail_will_not_modify -> Status = trail_will_not_modify ; Status = trail_may_modify ), !:Goal = if_then_else(Vars, If, Then, Else). annotate_goal_2(_, _, !Goal, Status, !ModuleInfo, !IO) :- !.Goal = call_foreign_proc(Attributes, _, _, _, _, _, _), Status = attributes_imply_trail_mod(Attributes). annotate_goal_2(_, _, shorthand(_), _, _, _, _, _, _) :- unexpected(this_file, "shorthand goal"). :- pred annotate_goal_list(vartypes::in, hlds_goals::in, hlds_goals::out, trailing_status::out, module_info::in, module_info::out, io::di, io::uo) is det. annotate_goal_list(VarTypes, !Goals, Status, !ModuleInfo, !IO) :- list.map2_foldl2(annotate_goal(VarTypes), !Goals, Statuses, !ModuleInfo, !IO), list.foldl(combine_trailing_status, Statuses, trail_will_not_modify, Status). :- pred annotate_cases(vartypes::in, list(case)::in, list(case)::out, trailing_status::out, module_info::in, module_info::out, io::di, io::uo) is det. annotate_cases(VarTypes, !Cases, Status, !ModuleInfo, !IO) :- list.map2_foldl2(annotate_case(VarTypes), !Cases, Statuses, !ModuleInfo, !IO), list.foldl(combine_trailing_status, Statuses, trail_will_not_modify, Status). :- pred annotate_case(vartypes::in, case::in, case::out, trailing_status::out, module_info::in, module_info::out, io::di, io::uo) is det. annotate_case(VarTypes, !Case, Status, !ModuleInfo, !IO) :- !.Case = case(ConsId, Goal0), annotate_goal(VarTypes, Goal0, Goal, Status, !ModuleInfo, !IO), !:Case = case(ConsId, Goal). %----------------------------------------------------------------------------% % % Stuff for intermodule optimization % :- pred make_opt_int(module_info::in, io::di, io::uo) is det. make_opt_int(ModuleInfo, !IO) :- module_info_get_name(ModuleInfo, ModuleName), module_name_to_file_name(ModuleName, ".opt.tmp", no, OptFileName, !IO), globals.io_lookup_bool_option(verbose, Verbose, !IO), maybe_write_string(Verbose, "% Appending trailing_info pragmas to `", !IO), maybe_write_string(Verbose, OptFileName, !IO), maybe_write_string(Verbose, "'...", !IO), maybe_flush_output(Verbose, !IO), io.open_append(OptFileName, OptFileRes, !IO), ( OptFileRes = ok(OptFile), io.set_output_stream(OptFile, OldStream, !IO), module_info_get_trailing_info(ModuleInfo, TrailingInfo), module_info_predids(PredIds, ModuleInfo, _ModuleInfo), list.foldl(write_pragma_trailing_info(ModuleInfo, TrailingInfo), PredIds, !IO), io.set_output_stream(OldStream, _, !IO), io.close_output(OptFile, !IO), maybe_write_string(Verbose, " done.\n", !IO) ; OptFileRes = error(IOError), maybe_write_string(Verbose, " failed!\n", !IO), io.error_message(IOError, IOErrorMessage), io.write_strings(["Error opening file `", OptFileName, "' for output: ", IOErrorMessage], !IO), io.set_exit_status(1, !IO) ). write_pragma_trailing_info(ModuleInfo, TrailingInfo, PredId, !IO) :- module_info_pred_info(ModuleInfo, PredId, PredInfo), should_write_trailing_info(ModuleInfo, PredId, PredInfo, ShouldWrite), ( ShouldWrite = yes, ModuleName = pred_info_module(PredInfo), Name = pred_info_name(PredInfo), Arity = pred_info_orig_arity(PredInfo), PredOrFunc = pred_info_is_pred_or_func(PredInfo), ProcIds = pred_info_procids(PredInfo), list.foldl((pred(ProcId::in, !.IO::di, !:IO::uo) is det :- proc_id_to_int(ProcId, ModeNum), ( map.search(TrailingInfo, proc(PredId, ProcId), ProcTrailInfo), ProcTrailInfo = proc_trailing_info(Status, _) -> mercury_output_pragma_trailing_info(PredOrFunc, qualified(ModuleName, Name), Arity, ModeNum, Status, !IO) ; true )), ProcIds, !IO) ; ShouldWrite = no ). :- pred should_write_trailing_info(module_info::in, pred_id::in, pred_info::in, bool::out) is det. should_write_trailing_info(ModuleInfo, PredId, PredInfo, ShouldWrite) :- pred_info_get_import_status(PredInfo, ImportStatus), ( ( ImportStatus = status_exported ; ImportStatus = status_opt_exported ), not is_unify_or_compare_pred(PredInfo), module_info_get_type_spec_info(ModuleInfo, TypeSpecInfo), TypeSpecInfo = type_spec_info(_, TypeSpecForcePreds, _, _), not set.member(PredId, TypeSpecForcePreds), % % XXX Writing out pragmas for the automatically generated class % instance methods causes the compiler to abort when it reads them % back in. % pred_info_get_markers(PredInfo, Markers), not check_marker(Markers, marker_class_instance_method), not check_marker(Markers, marker_named_class_instance_method) -> ShouldWrite = yes ; ShouldWrite = no ). %-----------------------------------------------------------------------------% % % Stuff for the intermodule analysis framework % :- type trailing_analysis_answer ---> trailing_analysis_answer(trailing_status). :- func analysis_name = string. analysis_name = "trail_usage". :- instance analysis(any_call, trailing_analysis_answer) where [ analysis_name(_, _) = analysis_name, analysis_version_number(_, _) = 1, preferred_fixpoint_type(_, _) = least_fixpoint, bottom(_) = trailing_analysis_answer(trail_will_not_modify), top(_) = trailing_analysis_answer(trail_may_modify) ]. :- instance answer_pattern(trailing_analysis_answer) where []. :- instance partial_order(trailing_analysis_answer) where [ (more_precise_than( trailing_analysis_answer(Status1), trailing_analysis_answer(Status2)) :- trailing_status_more_precise_than(Status1, Status2)), equivalent(Status, Status) ]. :- pred trailing_status_more_precise_than(trailing_status::in, trailing_status::in) is semidet. trailing_status_more_precise_than(trail_will_not_modify, trail_may_modify). trailing_status_more_precise_than(trail_will_not_modify, trail_conditional). trailing_status_more_precise_than(trail_conditional, trail_may_modify). :- instance to_string(trailing_analysis_answer) where [ func(to_string/1) is trailing_analysis_answer_to_string, func(from_string/1) is trailing_analysis_answer_from_string ]. :- func trailing_analysis_answer_to_string(trailing_analysis_answer) = string. trailing_analysis_answer_to_string(trailing_analysis_answer(Status)) = Str :- trailing_status_to_string(Status, Str). :- func trailing_analysis_answer_from_string(string) = trailing_analysis_answer is semidet. trailing_analysis_answer_from_string(Str) = trailing_analysis_answer(Status) :- trailing_status_to_string(Status, Str). :- pred trailing_status_to_string(trailing_status, string). :- mode trailing_status_to_string(in, out) is det. :- mode trailing_status_to_string(out, in) is semidet. trailing_status_to_string(trail_may_modify, "may_modify_trail"). trailing_status_to_string(trail_will_not_modify, "will_not_modify_trail"). trailing_status_to_string(trail_conditional, "conditional"). :- pred search_analysis_status(pred_proc_id::in, trailing_status::out, analysis_status::out, scc::in, module_info::in, module_info::out, io::di, io::uo) is det. search_analysis_status(PPId, Result, AnalysisStatus, CallerSCC, !ModuleInfo, !IO) :- module_info_get_analysis_info(!.ModuleInfo, AnalysisInfo0), search_analysis_status_2(!.ModuleInfo, PPId, Result, AnalysisStatus, CallerSCC, AnalysisInfo0, AnalysisInfo, !IO), module_info_set_analysis_info(AnalysisInfo, !ModuleInfo). :- pred search_analysis_status_2(module_info::in, pred_proc_id::in, trailing_status::out, analysis_status::out, scc::in, analysis_info::in, analysis_info::out, io::di, io::uo) is det. search_analysis_status_2(ModuleInfo, PPId, Result, AnalysisStatus, CallerSCC, !AnalysisInfo, !IO) :- mmc_analysis.module_id_func_id(ModuleInfo, PPId, ModuleId, FuncId), Call = any_call, analysis.lookup_best_result(ModuleId, FuncId, Call, MaybeBestStatus, !AnalysisInfo, !IO), globals.io_lookup_bool_option(make_analysis_registry, MakeAnalysisRegistry, !IO), ( MaybeBestStatus = yes({BestCall, trailing_analysis_answer(Result), AnalysisStatus}), ( MakeAnalysisRegistry = yes, record_dependencies(ModuleId, FuncId, BestCall, ModuleInfo, CallerSCC, !AnalysisInfo) ; MakeAnalysisRegistry = no ) ; MaybeBestStatus = no, % If we do not have any information about the callee procedure % then assume that it modifies the trail. top(Call) = Answer, Answer = trailing_analysis_answer(Result), module_is_local(mmc, ModuleId, IsLocal, !IO), ( IsLocal = yes, AnalysisStatus = suboptimal, ( MakeAnalysisRegistry = yes, PPId = proc(PredId, _), module_info_pred_info(ModuleInfo, PredId, PredInfo), should_write_trailing_info(ModuleInfo, PredId, PredInfo, ShouldWrite), ( ShouldWrite = yes, analysis.record_result(ModuleId, FuncId, Call, Answer, AnalysisStatus, !AnalysisInfo), analysis.record_request(analysis_name, ModuleId, FuncId, Call, !AnalysisInfo), record_dependencies(ModuleId, FuncId, Call, ModuleInfo, CallerSCC, !AnalysisInfo) ; ShouldWrite = no ) ; MakeAnalysisRegistry = no ) ; IsLocal = no, % We can't do any better anyway. AnalysisStatus = optimal ) ). % XXX if the procedures in CallerSCC definitely come from the % same module then we don't need to record the dependency so many % times, at least while we only have module-level granularity. % :- pred record_dependencies(module_id::in, func_id::in, Call::in, module_info::in, scc::in, analysis_info::in, analysis_info::out) is det <= call_pattern(Call). record_dependencies(ModuleId, FuncId, Call, ModuleInfo, CallerSCC, !AnalysisInfo) :- list.foldl((pred(CallerPPId::in, Info0::in, Info::out) is det :- mmc_analysis.module_id_func_id(ModuleInfo, CallerPPId, CallerModuleId, _), analysis.record_dependency(CallerModuleId, analysis_name, ModuleId, FuncId, Call, Info0, Info) ), CallerSCC, !AnalysisInfo). :- pred record_trailing_analysis_results(trailing_status::in, analysis_status::in, scc::in, module_info::in, module_info::out) is det. record_trailing_analysis_results(Status, ResultStatus, SCC, !ModuleInfo) :- module_info_get_analysis_info(!.ModuleInfo, AnalysisInfo0), list.foldl( record_trailing_analysis_result(!.ModuleInfo, Status, ResultStatus), SCC, AnalysisInfo0, AnalysisInfo), module_info_set_analysis_info(AnalysisInfo, !ModuleInfo). :- pred record_trailing_analysis_result(module_info::in, trailing_status::in, analysis_status::in, pred_proc_id::in, analysis_info::in, analysis_info::out) is det. record_trailing_analysis_result(ModuleInfo, Status, ResultStatus, PPId @ proc(PredId, _ProcId), AnalysisInfo0, AnalysisInfo) :- module_info_pred_info(ModuleInfo, PredId, PredInfo), should_write_trailing_info(ModuleInfo, PredId, PredInfo, ShouldWrite), ( ShouldWrite = yes, mmc_analysis.module_id_func_id(ModuleInfo, PPId, ModuleId, FuncId), analysis.record_result(ModuleId, FuncId, any_call, trailing_analysis_answer(Status), ResultStatus, AnalysisInfo0, AnalysisInfo) ; ShouldWrite = no, AnalysisInfo = AnalysisInfo0 ). %----------------------------------------------------------------------------% % % Code for printing out debugging traces % :- pred dump_trail_usage_debug_info(module_info::in, scc::in, trailing_status::in, io::di, io::uo) is det. dump_trail_usage_debug_info(ModuleInfo, SCC, Status, !IO) :- io.write_string("SCC: ", !IO), io.write(Status, !IO), io.nl(!IO), output_proc_names(ModuleInfo, SCC, !IO), io.nl(!IO). :- pred output_proc_names(module_info::in, scc::in, io::di, io::uo) is det. output_proc_names(ModuleInfo, SCC, !IO) :- list.foldl(output_proc_name(ModuleInfo), SCC, !IO). :- pred output_proc_name(module_info::in, pred_proc_id::in, io::di, io::uo) is det. output_proc_name(Moduleinfo, PPId, !IO) :- Pieces = describe_one_proc_name(Moduleinfo, should_module_qualify, PPId), Str = error_pieces_to_string(Pieces), io.format("\t%s\n", [s(Str)], !IO). %----------------------------------------------------------------------------% :- func this_file = string. this_file = "trailing_analysis.m". %----------------------------------------------------------------------------% :- end_module trailing_analysis. %----------------------------------------------------------------------------%