Files
mercury/compiler/optimize.m
Zoltan Somogyi 71be24b603 Optimize code sequences such as
Estimated hours taken: 1
Branches: main

Optimize code sequences such as

	mkframe(framesize, do_fail)
	...
	if (...) goto ...
	...
	succeed()

in which the ...s do not contains labels or update any of the control slots
of the frame. The optimization is replacing the succeed with a succeed_discard,
avoiding a future backtrack that cannot succeed.

compiler/peephole.m:
	Look for the pattern and act on it.

	Rejig the arguments of peephole's main predicate to avoid the need to
	rebuild the original instruction on the heap by passing it whole,
	instead of in pieces.

	Rename predicates to avoid the need for module qualification.

compiler/opt_util.m:
	Add a utility predicate needed by peephole.

compiler/optimize.m:
	Conform to the predicate renames in peephole.
2007-01-23 07:00:38 +00:00

690 lines
24 KiB
Mathematica

%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 1996-2007 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: optimize.m.
% Main author: zs.
%
% This module contains LLDS to LLDS optimizations.
%
%-----------------------------------------------------------------------------%
:- module ll_backend.optimize.
:- interface.
:- import_module ll_backend.global_data.
:- import_module ll_backend.llds.
:- import_module io.
:- import_module list.
%-----------------------------------------------------------------------------%
:- pred optimize_procs(global_data::in,
list(c_procedure)::in, list(c_procedure)::out, io::di, io::uo) is det.
:- pred optimize_proc(global_data::in, c_procedure::in, c_procedure::out,
io::di, io::uo) is det.
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module hlds.code_model.
:- import_module hlds.hlds_pred.
:- import_module libs.compiler_util.
:- import_module libs.globals.
:- import_module libs.options.
:- import_module ll_backend.continuation_info.
:- import_module ll_backend.delay_slot.
:- import_module ll_backend.dupelim.
:- import_module ll_backend.frameopt.
:- import_module ll_backend.jumpopt.
:- import_module ll_backend.labelopt.
:- import_module ll_backend.stdlabel.
:- import_module ll_backend.opt_debug.
:- import_module ll_backend.opt_util.
:- import_module ll_backend.peephole.
:- import_module ll_backend.reassign.
:- import_module ll_backend.use_local_vars.
:- import_module ll_backend.wrap_blocks.
:- import_module mdbcomp.prim_data.
:- import_module parse_tree.prog_out.
:- import_module bool.
:- import_module char.
:- import_module counter.
:- import_module dir.
:- import_module int.
:- import_module map.
:- import_module set.
:- import_module string.
%-----------------------------------------------------------------------------%
optimize_procs(GlobalData, !Procs, !IO) :-
list.map_foldl(optimize_proc(GlobalData), !Procs, !IO).
optimize_proc(GlobalData, CProc0, CProc, !IO) :-
some [!OptDebugInfo, !C, !Instrs] (
CProc0 = c_procedure(Name, Arity, PredProcId, CodeModel, !:Instrs,
ProcLabel, !:C, MayAlterRtti, CGlobalVars),
init_opt_debug_info(Name, Arity, PredProcId, ProcLabel,
!.Instrs, !.C, !:OptDebugInfo, !IO),
globals.io_lookup_int_option(optimize_repeat, Repeat, !IO),
(
global_data_maybe_get_proc_layout(GlobalData,
PredProcId, ProcLayout)
->
LabelMap = ProcLayout ^ internal_map,
map.sorted_keys(LabelMap, LayoutLabelNums),
LayoutLabels = list.map(
make_internal_label_for_proc_label(ProcLabel),
LayoutLabelNums),
set.sorted_list_to_set(LayoutLabels, LayoutLabelSet)
;
set.init(LayoutLabelSet)
),
optimize_initial(LayoutLabelSet, ProcLabel, CodeModel, MayAlterRtti,
!C, !OptDebugInfo, !Instrs, !IO),
optimize_repeat(Repeat, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
!OptDebugInfo, !Instrs, !IO),
optimize_middle(yes, LayoutLabelSet, ProcLabel, CodeModel,
MayAlterRtti, !C, !OptDebugInfo, !Instrs, !IO),
optimize_last(LayoutLabelSet, ProcLabel, !C, !.OptDebugInfo, !Instrs,
!IO),
CProc = c_procedure(Name, Arity, PredProcId, CodeModel, !.Instrs,
ProcLabel, !.C, MayAlterRtti, CGlobalVars)
).
:- func make_internal_label_for_proc_label(proc_label, int) = label.
make_internal_label_for_proc_label(ProcLabel, LabelNum)
= internal_label(LabelNum, ProcLabel).
%-----------------------------------------------------------------------------%
:- type opt_debug_info
---> opt_debug_info(
string, % Base file name for the dump files.
int, % The number of the last dump file written.
string, % The name of this file.
int, % The number of the last dump file written
% that has the instruction sequence in it.
string, % The name of this file.
list(instruction)
% The instruction sequence at the time the
% last dump file was written.
)
; no_opt_debug_info.
:- pred init_opt_debug_info(string::in, int::in, pred_proc_id::in,
proc_label::in, list(instruction)::in, counter::in, opt_debug_info::out,
io::di, io::uo) is det.
init_opt_debug_info(Name, Arity, PredProcId, ProcLabel, Instrs0, Counter,
OptDebugInfo, !IO) :-
globals.io_get_globals(Globals, !IO),
globals.lookup_bool_option(Globals, debug_opt, DebugOpt),
globals.lookup_accumulating_option(Globals, debug_opt_pred_id,
DebugOptPredIdStrs),
globals.lookup_accumulating_option(Globals, debug_opt_pred_name,
DebugOptPredNames),
PredProcId = proc(PredId, ProcId),
pred_id_to_int(PredId, PredIdInt),
proc_id_to_int(ProcId, ProcIdInt),
(
DebugOpt = yes,
(
DebugOptPredIdStrs = [_ | _],
DebugOptPredNames = [_ | _],
(
some [DebugOptPredIdStr, DebugOptPredId] (
list.member(DebugOptPredIdStr, DebugOptPredIdStrs),
string.to_int(DebugOptPredIdStr, DebugOptPredId),
DebugOptPredId = PredIdInt
)
;
list.member(Name, DebugOptPredNames)
)
;
DebugOptPredIdStrs = [_ | _],
DebugOptPredNames = [],
some [DebugOptPredIdStr, DebugOptPredId] (
list.member(DebugOptPredIdStr, DebugOptPredIdStrs),
string.to_int(DebugOptPredIdStr, DebugOptPredId),
DebugOptPredId = PredIdInt
)
;
DebugOptPredIdStrs = [],
DebugOptPredNames = [_ | _],
list.member(Name, DebugOptPredNames)
;
DebugOptPredIdStrs = [],
DebugOptPredNames = []
)
->
BaseName = opt_subdir_name ++ "/"
++ mangle_name_as_filename(Name) ++ "_" ++ int_to_string(Arity)
++ ".pred" ++ int_to_string(PredIdInt)
++ ".proc" ++ int_to_string(ProcIdInt),
io.call_system("mkdir -p " ++ opt_subdir_name, MkdirRes, !IO),
( MkdirRes = ok(0) ->
true
;
unexpected(this_file, "cannot make " ++ opt_subdir_name)
),
FileName = BaseName ++ ".opt" ++ num_to_str(0),
io.open_output(FileName, Res, !IO),
( Res = ok(FileStream) ->
io.set_output_stream(FileStream, OutputStream, !IO),
counter.allocate(NextLabel, Counter, _),
opt_debug.msg(yes, NextLabel, "before optimization", !IO),
opt_debug.maybe_dump_instrs(yes, ProcLabel, Instrs0, !IO),
io.set_output_stream(OutputStream, _, !IO),
io.close_output(FileStream, !IO)
;
unexpected(this_file, "cannot open " ++ FileName)
),
OptDebugInfo = opt_debug_info(BaseName, 0, FileName, 0, FileName,
Instrs0)
;
OptDebugInfo = no_opt_debug_info
).
:- func opt_subdir_name = string.
opt_subdir_name = "OptSubdir".
:- func num_to_str(int) = string.
num_to_str(N) =
( N < 10 ->
"0" ++ string.int_to_string(N)
;
string.int_to_string(N)
).
:- pred maybe_opt_debug(list(instruction)::in, counter::in,
string::in, string::in, proc_label::in,
opt_debug_info::in, opt_debug_info::out, io::di, io::uo) is det.
maybe_opt_debug(Instrs, Counter, Suffix, Msg, ProcLabel, !OptDebugInfo, !IO) :-
(
!.OptDebugInfo = opt_debug_info(BaseName, OptNum0, _OptFileName0,
PrevNum, PrevFileName, PrevInstrs),
( Instrs = PrevInstrs ->
Same = yes
;
Same = no
),
OptNum = OptNum0 + 1,
OptFileName = BaseName ++ ".opt" ++ num_to_str(OptNum)
++ "." ++ Suffix,
DiffFileName = BaseName ++ ".diff" ++ num_to_str(OptNum)
++ "." ++ Suffix,
io.open_output(OptFileName, Res, !IO),
( Res = ok(FileStream) ->
io.set_output_stream(FileStream, OutputStream, !IO),
counter.allocate(NextLabel, Counter, _),
opt_debug.msg(yes, NextLabel, Msg, !IO),
(
Same = yes,
io.write_string("same as previous version\n", !IO)
;
Same = no,
opt_debug.maybe_dump_instrs(yes, ProcLabel, Instrs, !IO)
),
io.set_output_stream(OutputStream, _, !IO),
io.close_output(FileStream, !IO)
;
ErrorMsg = "cannot open " ++ OptFileName,
unexpected(this_file, ErrorMsg)
),
(
Same = yes,
!:OptDebugInfo = opt_debug_info(BaseName, OptNum, OptFileName,
PrevNum, PrevFileName, Instrs)
;
Same = no,
% Although the -u is not fully portable, it is available
% on all the systems we intend to use it on, and the main user
% of --debug-opt (zs) strongly prefers -u to -c.
DiffCommand = "diff -u '" ++ PrevFileName ++ "' '" ++ OptFileName
++ "' > '" ++ DiffFileName ++ "'",
io.call_system(DiffCommand, _, !IO),
!:OptDebugInfo = opt_debug_info(BaseName, OptNum, OptFileName,
OptNum, OptFileName, Instrs)
)
;
!.OptDebugInfo = no_opt_debug_info
).
%-----------------------------------------------------------------------------%
:- pred optimize_initial(set(label)::in, proc_label::in, code_model::in,
may_alter_rtti::in, counter::in, counter::out,
opt_debug_info::in, opt_debug_info::out,
list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
optimize_initial(LayoutLabelSet, ProcLabel, CodeModel, MayAlterRtti,
!C, !OptDebugInfo, !Instrs, !IO) :-
globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
LabelStr = opt_util.format_proc_label(ProcLabel),
globals.io_lookup_bool_option(optimize_frames, FrameOpt, !IO),
(
FrameOpt = yes,
MayAlterRtti = may_alter_rtti,
CodeModel = model_non
->
(
VeryVerbose = yes,
io.write_string("% Optimizing nondet frames for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
frameopt_keep_nondet_frame(ProcLabel, LayoutLabelSet,
!C, !Instrs, _Mod),
maybe_opt_debug(!.Instrs, !.C, "ndframeopt", "after nondet frame opt",
ProcLabel, !OptDebugInfo, !IO)
;
true
).
%-----------------------------------------------------------------------------%
:- pred optimize_repeat(int::in, set(label)::in, proc_label::in,
may_alter_rtti::in, counter::in, counter::out,
opt_debug_info::in, opt_debug_info::out,
list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
optimize_repeat(CurIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
!C, !OptDebugInfo, !Instrs, !IO) :-
( CurIter > 0 ->
NextIter = CurIter - 1,
( NextIter = 0 ->
Final = yes
;
Final = no
),
optimize_repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
!C, !OptDebugInfo, !Instrs, Mod, !IO),
(
Mod = yes,
optimize_repeat(NextIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
!C, !OptDebugInfo, !Instrs, !IO)
;
Mod = no
)
;
true
).
% We short-circuit jump sequences before normal peepholing
% to create more opportunities for use of the tailcall macro.
%
:- pred optimize_repeated(bool::in, set(label)::in, proc_label::in,
may_alter_rtti::in, counter::in, counter::out,
opt_debug_info::in, opt_debug_info::out,
list(instruction)::in, list(instruction)::out, bool::out,
io::di, io::uo) is det.
optimize_repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
!C, !OptDebugInfo, !Instrs, Mod, !IO) :-
InstrsAtStart = !.Instrs,
LabelStr = opt_util.format_proc_label(ProcLabel),
globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
globals.io_lookup_bool_option(optimize_jumps, Jumpopt, !IO),
globals.io_lookup_bool_option(optimize_fulljumps, FullJumpopt, !IO),
globals.io_lookup_bool_option(pessimize_tailcalls,
PessimizeTailCalls, !IO),
globals.io_lookup_bool_option(checked_nondet_tailcalls,
CheckedNondetTailCalls, !IO),
(
Jumpopt = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing jumps for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
optimize_jumps_in_proc(LayoutLabelSet, MayAlterRtti, ProcLabel,
FullJumpopt, Final, PessimizeTailCalls, CheckedNondetTailCalls,
!C, !Instrs, Mod1),
maybe_opt_debug(!.Instrs, !.C, "jump", "after jump opt",
ProcLabel, !OptDebugInfo, !IO)
;
Jumpopt = no,
Mod1 = no
),
globals.io_lookup_bool_option(optimize_peep, Peephole, !IO),
(
Peephole = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing locally for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
globals.io_get_gc_method(GC_Method, !IO),
peephole_optimize(GC_Method, !Instrs, Mod2),
maybe_opt_debug(!.Instrs, !.C, "peep", "after peephole",
ProcLabel, !OptDebugInfo, !IO)
;
Peephole = no,
Mod2 = no
),
globals.io_lookup_bool_option(optimize_labels, LabelElim, !IO),
(
LabelElim = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing labels for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
labelopt_main(Final, LayoutLabelSet, !Instrs, Mod3),
maybe_opt_debug(!.Instrs, !.C, "label", "after label opt",
ProcLabel, !OptDebugInfo, !IO)
;
LabelElim = no,
Mod3 = no
),
globals.io_lookup_bool_option(optimize_dups, DupElim, !IO),
(
DupElim = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing duplicates for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
dupelim_main(ProcLabel, !C, !Instrs),
maybe_opt_debug(!.Instrs, !.C, "dup", "after duplicates",
ProcLabel, !OptDebugInfo, !IO)
;
DupElim = no
),
( Mod1 = no, Mod2 = no, Mod3 = no, !.Instrs = InstrsAtStart ->
Mod = no
;
Mod = yes
),
globals.io_lookup_bool_option(detailed_statistics, Statistics, !IO),
maybe_report_stats(Statistics, !IO).
:- pred optimize_middle(bool::in, set(label)::in, proc_label::in,
code_model::in, may_alter_rtti::in, counter::in, counter::out,
opt_debug_info::in, opt_debug_info::out,
list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
optimize_middle(Final, LayoutLabelSet, ProcLabel, CodeModel, MayAlterRtti, !C,
!OptDebugInfo, !Instrs, !IO) :-
globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
LabelStr = opt_util.format_proc_label(ProcLabel),
globals.io_lookup_bool_option(optimize_frames, FrameOpt, !IO),
(
FrameOpt = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing frames for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
globals.io_get_globals(Globals, !IO),
(
( CodeModel = model_det
; CodeModel = model_semi
),
frameopt_main_det_stack(ProcLabel, !C, !Instrs, Globals, Mod1)
;
CodeModel = model_non,
frameopt_main_nondet_stack(ProcLabel, !C, !Instrs, Globals, Mod1)
),
maybe_opt_debug(!.Instrs, !.C, "frame", "after frame opt",
ProcLabel, !OptDebugInfo, !IO),
globals.io_lookup_bool_option(optimize_fulljumps, FullJumpopt, !IO),
globals.io_lookup_bool_option(pessimize_tailcalls,
PessimizeTailCalls, !IO),
globals.io_lookup_bool_option(checked_nondet_tailcalls,
CheckedNondetTailCalls, !IO),
(
( FullJumpopt = yes
; Mod1 = yes
)
->
(
VeryVerbose = yes,
io.write_string("% Optimizing jumps for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
optimize_jumps_in_proc(LayoutLabelSet, MayAlterRtti, ProcLabel,
FullJumpopt, Final, PessimizeTailCalls, CheckedNondetTailCalls,
!C, !Instrs, _Mod2),
maybe_opt_debug(!.Instrs, !.C, "jump", "after jumps",
ProcLabel, !OptDebugInfo, !IO)
;
true
),
(
Mod1 = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing labels for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
labelopt_main(Final, LayoutLabelSet, !Instrs, _Mod3),
maybe_opt_debug(!.Instrs, !.C, "label", "after labels",
ProcLabel, !OptDebugInfo, !IO)
;
Mod1 = no
),
(
Mod1 = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing locally for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
globals.io_get_gc_method(GC_Method, !IO),
peephole_optimize(GC_Method, !Instrs, _Mod),
maybe_opt_debug(!.Instrs, !.C, "peep", "after peephole",
ProcLabel, !OptDebugInfo, !IO)
;
Mod1 = no
)
;
FrameOpt = no
),
globals.io_lookup_bool_option(use_local_vars, UseLocalVars, !IO),
(
UseLocalVars = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing local vars for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
globals.io_lookup_int_option(num_real_r_regs, NumRealRRegs, !IO),
globals.io_lookup_int_option(local_var_access_threshold,
AccessThreshold, !IO),
globals.io_lookup_bool_option(auto_comments, AutoComments, !IO),
use_local_vars_proc(!Instrs, NumRealRRegs, AccessThreshold,
AutoComments, ProcLabel, !C),
maybe_opt_debug(!.Instrs, !.C, "use_local", "after use_local_vars",
ProcLabel, !OptDebugInfo, !IO)
;
UseLocalVars = no
).
:- pred optimize_last(set(label)::in, proc_label::in,
counter::in, counter::out, opt_debug_info::in,
list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
optimize_last(LayoutLabelSet, ProcLabel, !C, !.OptDebugInfo, !Instrs, !IO) :-
globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
LabelStr = opt_util.format_proc_label(ProcLabel),
globals.io_lookup_bool_option(optimize_reassign, Reassign, !IO),
globals.io_lookup_bool_option(optimize_delay_slot, DelaySlot, !IO),
globals.io_lookup_bool_option(use_local_vars, UseLocalVars, !IO),
globals.io_lookup_bool_option(standardize_labels, StdLabels, !IO),
(
( Reassign = yes
; DelaySlot = yes
; UseLocalVars = yes
; StdLabels = yes
)
->
% We must get rid of any extra labels added by other passes,
% since they can confuse reassign, wrap_blocks and delay_slot.
(
VeryVerbose = yes,
io.write_string("% Optimizing labels for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
labelopt_main(no, LayoutLabelSet, !Instrs, _Mod1),
maybe_opt_debug(!.Instrs, !.C, "label", "after label opt",
ProcLabel, !OptDebugInfo, !IO)
;
true
),
(
Reassign = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing reassign for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
remove_reassign(!Instrs),
maybe_opt_debug(!.Instrs, !.C, "reassign", "after reassign",
ProcLabel, !OptDebugInfo, !IO)
;
Reassign = no
),
(
DelaySlot = yes,
(
VeryVerbose = yes,
io.write_string("% Optimizing delay slot for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
fill_branch_delay_slot(!Instrs),
maybe_opt_debug(!.Instrs, !.C, "delay_slot", "after delay slots",
ProcLabel, !OptDebugInfo, !IO)
;
DelaySlot = no
),
(
VeryVerbose = yes,
io.write_string("% Optimizing returns for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
combine_decr_sp(!Instrs),
maybe_opt_debug(!.Instrs, !.C, "decr_sp", "after combine decr_sp",
ProcLabel, !OptDebugInfo, !IO),
(
StdLabels = yes,
(
VeryVerbose = yes,
io.write_string("% Standardizing labels for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
standardize_labels(!Instrs, !C),
maybe_opt_debug(!.Instrs, !.C, "stdlabel", "after standard labels",
ProcLabel, !OptDebugInfo, !IO)
;
StdLabels = no
),
(
UseLocalVars = yes,
(
VeryVerbose = yes,
io.write_string("% Wrapping blocks for ", !IO),
io.write_string(LabelStr, !IO),
io.write_string("\n", !IO)
;
VeryVerbose = no
),
wrap_blocks(!Instrs),
maybe_opt_debug(!.Instrs, !.C, "wrapblocks", "after wrap blocks",
ProcLabel, !.OptDebugInfo, _OptDebugInfo, !IO)
;
UseLocalVars = no
).
%-----------------------------------------------------------------------------%
% Mangle the given name just sufficiently to make it acceptable as a
% filename.
%
:- func mangle_name_as_filename(string) = string.
mangle_name_as_filename(Str0) = Str :-
string.foldl(escape_dir_char, Str0, "", Str).
:- pred escape_dir_char(char::in, string::in, string::out) is det.
escape_dir_char(Char, !Str) :-
( dir.is_directory_separator(Char) ->
!:Str = !.Str ++ "_slash_"
;
!:Str = !.Str ++ char_to_string(Char)
).
%-----------------------------------------------------------------------------%
:- func this_file = string.
this_file = "optimize".
%-----------------------------------------------------------------------------%
:- end_module optimize.
%-----------------------------------------------------------------------------%