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1# B.pm
2#
1a52ab62 3# Copyright (c) 1996, 1997, 1998 Malcolm Beattie
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4#
5# You may distribute under the terms of either the GNU General Public
6# License or the Artistic License, as specified in the README file.
7#
8package B;
9require DynaLoader;
10require Exporter;
11@ISA = qw(Exporter DynaLoader);
12@EXPORT_OK = qw(byteload_fh byteload_string minus_c ppname
13 class peekop cast_I32 cstring cchar hash threadsv_names
14 main_root main_start main_cv svref_2object
15 walkoptree walkoptree_slow walkoptree_exec walksymtable
16 parents comppadlist sv_undef compile_stats timing_info);
17
18use strict;
19@B::SV::ISA = 'B::OBJECT';
20@B::NULL::ISA = 'B::SV';
21@B::PV::ISA = 'B::SV';
22@B::IV::ISA = 'B::SV';
23@B::NV::ISA = 'B::IV';
24@B::RV::ISA = 'B::SV';
25@B::PVIV::ISA = qw(B::PV B::IV);
26@B::PVNV::ISA = qw(B::PV B::NV);
27@B::PVMG::ISA = 'B::PVNV';
28@B::PVLV::ISA = 'B::PVMG';
29@B::BM::ISA = 'B::PVMG';
30@B::AV::ISA = 'B::PVMG';
31@B::GV::ISA = 'B::PVMG';
32@B::HV::ISA = 'B::PVMG';
33@B::CV::ISA = 'B::PVMG';
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34@B::IO::ISA = 'B::PVMG';
35@B::FM::ISA = 'B::CV';
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36
37@B::OP::ISA = 'B::OBJECT';
38@B::UNOP::ISA = 'B::OP';
39@B::BINOP::ISA = 'B::UNOP';
40@B::LOGOP::ISA = 'B::UNOP';
41@B::CONDOP::ISA = 'B::UNOP';
42@B::LISTOP::ISA = 'B::BINOP';
43@B::SVOP::ISA = 'B::OP';
44@B::GVOP::ISA = 'B::OP';
45@B::PVOP::ISA = 'B::OP';
46@B::CVOP::ISA = 'B::OP';
47@B::LOOP::ISA = 'B::LISTOP';
48@B::PMOP::ISA = 'B::LISTOP';
49@B::COP::ISA = 'B::OP';
50
51@B::SPECIAL::ISA = 'B::OBJECT';
52
53{
54 # Stop "-w" from complaining about the lack of a real B::OBJECT class
55 package B::OBJECT;
56}
57
58my $debug;
59my $op_count = 0;
60my @parents = ();
61
62sub debug {
63 my ($class, $value) = @_;
64 $debug = $value;
65 walkoptree_debug($value);
66}
67
68# sub OPf_KIDS;
69# add to .xs for perl5.002
70sub OPf_KIDS () { 4 }
71
72sub class {
73 my $obj = shift;
74 my $name = ref $obj;
75 $name =~ s/^.*:://;
76 return $name;
77}
78
79sub parents { \@parents }
80
81# For debugging
82sub peekop {
83 my $op = shift;
84 return sprintf("%s (0x%x) %s", class($op), $$op, $op->ppaddr);
85}
86
87sub walkoptree_slow {
88 my($op, $method, $level) = @_;
89 $op_count++; # just for statistics
90 $level ||= 0;
91 warn(sprintf("walkoptree: %d. %s\n", $level, peekop($op))) if $debug;
92 $op->$method($level);
93 if ($$op && ($op->flags & OPf_KIDS)) {
94 my $kid;
95 unshift(@parents, $op);
96 for ($kid = $op->first; $$kid; $kid = $kid->sibling) {
97 walkoptree_slow($kid, $method, $level + 1);
98 }
99 shift @parents;
100 }
101}
102
103sub compile_stats {
104 return "Total number of OPs processed: $op_count\n";
105}
106
107sub timing_info {
108 my ($sec, $min, $hr) = localtime;
109 my ($user, $sys) = times;
110 sprintf("%02d:%02d:%02d user=$user sys=$sys",
111 $hr, $min, $sec, $user, $sys);
112}
113
114my %symtable;
115sub savesym {
116 my ($obj, $value) = @_;
117# warn(sprintf("savesym: sym_%x => %s\n", $$obj, $value)); # debug
118 $symtable{sprintf("sym_%x", $$obj)} = $value;
119}
120
121sub objsym {
122 my $obj = shift;
123 return $symtable{sprintf("sym_%x", $$obj)};
124}
125
126sub walkoptree_exec {
127 my ($op, $method, $level) = @_;
128 my ($sym, $ppname);
129 my $prefix = " " x $level;
130 for (; $$op; $op = $op->next) {
131 $sym = objsym($op);
132 if (defined($sym)) {
133 print $prefix, "goto $sym\n";
134 return;
135 }
136 savesym($op, sprintf("%s (0x%lx)", class($op), $$op));
137 $op->$method($level);
138 $ppname = $op->ppaddr;
139 if ($ppname =~ /^pp_(or|and|mapwhile|grepwhile|entertry)$/) {
140 print $prefix, uc($1), " => {\n";
141 walkoptree_exec($op->other, $method, $level + 1);
142 print $prefix, "}\n";
143 } elsif ($ppname eq "pp_match" || $ppname eq "pp_subst") {
144 my $pmreplstart = $op->pmreplstart;
145 if ($$pmreplstart) {
146 print $prefix, "PMREPLSTART => {\n";
147 walkoptree_exec($pmreplstart, $method, $level + 1);
148 print $prefix, "}\n";
149 }
150 } elsif ($ppname eq "pp_substcont") {
151 print $prefix, "SUBSTCONT => {\n";
152 walkoptree_exec($op->other->pmreplstart, $method, $level + 1);
153 print $prefix, "}\n";
154 $op = $op->other;
155 } elsif ($ppname eq "pp_cond_expr") {
156 # pp_cond_expr never returns op_next
157 print $prefix, "TRUE => {\n";
158 walkoptree_exec($op->true, $method, $level + 1);
159 print $prefix, "}\n";
160 $op = $op->false;
161 redo;
162 } elsif ($ppname eq "pp_range") {
163 print $prefix, "TRUE => {\n";
164 walkoptree_exec($op->true, $method, $level + 1);
165 print $prefix, "}\n", $prefix, "FALSE => {\n";
166 walkoptree_exec($op->false, $method, $level + 1);
167 print $prefix, "}\n";
168 } elsif ($ppname eq "pp_enterloop") {
169 print $prefix, "REDO => {\n";
170 walkoptree_exec($op->redoop, $method, $level + 1);
171 print $prefix, "}\n", $prefix, "NEXT => {\n";
172 walkoptree_exec($op->nextop, $method, $level + 1);
173 print $prefix, "}\n", $prefix, "LAST => {\n";
174 walkoptree_exec($op->lastop, $method, $level + 1);
175 print $prefix, "}\n";
176 } elsif ($ppname eq "pp_subst") {
177 my $replstart = $op->pmreplstart;
178 if ($$replstart) {
179 print $prefix, "SUBST => {\n";
180 walkoptree_exec($replstart, $method, $level + 1);
181 print $prefix, "}\n";
182 }
183 }
184 }
185}
186
187sub walksymtable {
188 my ($symref, $method, $recurse, $prefix) = @_;
189 my $sym;
190 no strict 'vars';
191 local(*glob);
192 while (($sym, *glob) = each %$symref) {
193 if ($sym =~ /::$/) {
194 $sym = $prefix . $sym;
195 if ($sym ne "main::" && &$recurse($sym)) {
196 walksymtable(\%glob, $method, $recurse, $sym);
197 }
198 } else {
199 svref_2object(\*glob)->EGV->$method();
200 }
201 }
202}
203
204{
205 package B::Section;
206 my $output_fh;
207 my %sections;
208
209 sub new {
210 my ($class, $section, $symtable, $default) = @_;
211 $output_fh ||= FileHandle->new_tmpfile;
212 my $obj = bless [-1, $section, $symtable, $default], $class;
213 $sections{$section} = $obj;
214 return $obj;
215 }
216
217 sub get {
218 my ($class, $section) = @_;
219 return $sections{$section};
220 }
221
222 sub add {
223 my $section = shift;
224 while (defined($_ = shift)) {
225 print $output_fh "$section->[1]\t$_\n";
226 $section->[0]++;
227 }
228 }
229
230 sub index {
231 my $section = shift;
232 return $section->[0];
233 }
234
235 sub name {
236 my $section = shift;
237 return $section->[1];
238 }
239
240 sub symtable {
241 my $section = shift;
242 return $section->[2];
243 }
244
245 sub default {
246 my $section = shift;
247 return $section->[3];
248 }
249
250 sub output {
251 my ($section, $fh, $format) = @_;
252 my $name = $section->name;
253 my $sym = $section->symtable || {};
254 my $default = $section->default;
255
256 seek($output_fh, 0, 0);
257 while (<$output_fh>) {
258 chomp;
259 s/^(.*?)\t//;
260 if ($1 eq $name) {
261 s{(s\\_[0-9a-f]+)} {
262 exists($sym->{$1}) ? $sym->{$1} : $default;
263 }ge;
264 printf $fh $format, $_;
265 }
266 }
267 }
268}
269
270bootstrap B;
271
2721;
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273
274__END__
275
276=head1 NAME
277
278B - The Perl Compiler
279
280=head1 SYNOPSIS
281
282 use B;
283
284=head1 DESCRIPTION
285
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286The C<B> module supplies classes which allow a Perl program to delve
287into its own innards. It is the module used to implement the
288"backends" of the Perl compiler. Usage of the compiler does not
289require knowledge of this module: see the F<O> module for the
290user-visible part. The C<B> module is of use to those who want to
291write new compiler backends. This documentation assumes that the
292reader knows a fair amount about perl's internals including such
293things as SVs, OPs and the internal symbol table and syntax tree
294of a program.
295
296=head1 OVERVIEW OF CLASSES
297
298The C structures used by Perl's internals to hold SV and OP
299information (PVIV, AV, HV, ..., OP, SVOP, UNOP, ...) are modelled on a
300class hierarchy and the C<B> module gives access to them via a true
301object hierarchy. Structure fields which point to other objects
302(whether types of SV or types of OP) are represented by the C<B>
303module as Perl objects of the appropriate class. The bulk of the C<B>
304module is the methods for accessing fields of these structures. Note
305that all access is read-only: you cannot modify the internals by
306using this module.
307
308=head2 SV-RELATED CLASSES
309
310B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM, B::PVLV,
311B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes correspond in
312the obvious way to the underlying C structures of similar names. The
313inheritance hierarchy mimics the underlying C "inheritance". Access
314methods correspond to the underlying C macros for field access,
315usually with the leading "class indication" prefix removed (Sv, Av,
316Hv, ...). The leading prefix is only left in cases where its removal
317would cause a clash in method name. For example, C<GvREFCNT> stays
318as-is since its abbreviation would clash with the "superclass" method
319C<REFCNT> (corresponding to the C function C<SvREFCNT>).
320
321=head2 B::SV METHODS
322
323=over 4
324
325=item REFCNT
326
327=item FLAGS
328
329=back
330
331=head2 B::IV METHODS
332
333=over 4
334
335=item IV
336
337=item IVX
338
339=item needs64bits
340
341=item packiv
342
343=back
344
345=head2 B::NV METHODS
346
347=over 4
348
349=item NV
350
351=item NVX
352
353=back
354
355=head2 B::RV METHODS
356
357=over 4
358
359=item RV
360
361=back
362
363=head2 B::PV METHODS
364
365=over 4
366
367=item PV
368
369=back
370
371=head2 B::PVMG METHODS
372
373=over 4
374
375=item MAGIC
376
377=item SvSTASH
378
379=back
380
381=head2 B::MAGIC METHODS
382
383=over 4
384
385=item MOREMAGIC
386
387=item PRIVATE
388
389=item TYPE
390
391=item FLAGS
392
393=item OBJ
394
395=item PTR
396
397=back
398
399=head2 B::PVLV METHODS
400
401=over 4
402
403=item TARGOFF
404
405=item TARGLEN
406
407=item TYPE
408
409=item TARG
410
411=back
412
413=head2 B::BM METHODS
414
415=over 4
416
417=item USEFUL
418
419=item PREVIOUS
420
421=item RARE
422
423=item TABLE
424
425=back
426
427=head2 B::GV METHODS
428
429=over 4
430
431=item NAME
432
433=item STASH
434
435=item SV
436
437=item IO
438
439=item FORM
440
441=item AV
442
443=item HV
444
445=item EGV
446
447=item CV
448
449=item CVGEN
450
451=item LINE
452
453=item FILEGV
454
455=item GvREFCNT
456
457=item FLAGS
458
459=back
460
461=head2 B::IO METHODS
462
463=over 4
464
465=item LINES
466
467=item PAGE
468
469=item PAGE_LEN
470
471=item LINES_LEFT
472
473=item TOP_NAME
474
475=item TOP_GV
476
477=item FMT_NAME
478
479=item FMT_GV
480
481=item BOTTOM_NAME
482
483=item BOTTOM_GV
484
485=item SUBPROCESS
486
487=item IoTYPE
488
489=item IoFLAGS
490
491=back
492
493=head2 B::AV METHODS
494
495=over 4
496
497=item FILL
498
499=item MAX
500
501=item OFF
502
503=item ARRAY
504
505=item AvFLAGS
506
507=back
508
509=head2 B::CV METHODS
510
511=over 4
512
513=item STASH
514
515=item START
516
517=item ROOT
518
519=item GV
520
521=item FILEGV
522
523=item DEPTH
524
525=item PADLIST
526
527=item OUTSIDE
528
529=item XSUB
530
531=item XSUBANY
532
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533=item CvFLAGS
534
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535=back
536
537=head2 B::HV METHODS
538
539=over 4
540
541=item FILL
542
543=item MAX
544
545=item KEYS
546
547=item RITER
548
549=item NAME
550
551=item PMROOT
552
553=item ARRAY
554
555=back
556
557=head2 OP-RELATED CLASSES
558
559B::OP, B::UNOP, B::BINOP, B::LOGOP, B::CONDOP, B::LISTOP, B::PMOP,
560B::SVOP, B::GVOP, B::PVOP, B::CVOP, B::LOOP, B::COP.
561These classes correspond in
562the obvious way to the underlying C structures of similar names. The
563inheritance hierarchy mimics the underlying C "inheritance". Access
564methods correspond to the underlying C structre field names, with the
565leading "class indication" prefix removed (op_).
566
567=head2 B::OP METHODS
568
569=over 4
570
571=item next
572
573=item sibling
574
575=item ppaddr
576
577This returns the function name as a string (e.g. pp_add, pp_rv2av).
578
579=item desc
580
581This returns the op description from the global C op_desc array
582(e.g. "addition" "array deref").
583
584=item targ
585
586=item type
587
588=item seq
589
590=item flags
591
592=item private
593
594=back
595
596=head2 B::UNOP METHOD
597
598=over 4
599
600=item first
601
602=back
603
604=head2 B::BINOP METHOD
605
606=over 4
607
608=item last
609
610=back
611
612=head2 B::LOGOP METHOD
613
614=over 4
615
616=item other
617
618=back
619
620=head2 B::CONDOP METHODS
621
622=over 4
623
624=item true
625
626=item false
627
628=back
629
630=head2 B::LISTOP METHOD
631
632=over 4
633
634=item children
635
636=back
637
638=head2 B::PMOP METHODS
639
640=over 4
641
642=item pmreplroot
643
644=item pmreplstart
645
646=item pmnext
647
648=item pmregexp
649
650=item pmflags
651
652=item pmpermflags
653
654=item precomp
655
656=back
657
658=head2 B::SVOP METHOD
659
660=over 4
661
662=item sv
663
664=back
665
666=head2 B::GVOP METHOD
667
668=over 4
669
670=item gv
671
672=back
673
674=head2 B::PVOP METHOD
675
676=over 4
677
678=item pv
679
680=back
681
682=head2 B::LOOP METHODS
683
684=over 4
685
686=item redoop
687
688=item nextop
689
690=item lastop
691
692=back
693
694=head2 B::COP METHODS
695
696=over 4
697
698=item label
699
700=item stash
701
702=item filegv
703
704=item cop_seq
705
706=item arybase
707
708=item line
709
710=back
711
712=head1 FUNCTIONS EXPORTED BY C<B>
713
714The C<B> module exports a variety of functions: some are simple
715utility functions, others provide a Perl program with a way to
716get an initial "handle" on an internal object.
717
718=over 4
719
720=item main_cv
721
722Return the (faked) CV corresponding to the main part of the Perl
723program.
724
725=item main_root
726
727Returns the root op (i.e. an object in the appropriate B::OP-derived
728class) of the main part of the Perl program.
729
730=item main_start
731
732Returns the starting op of the main part of the Perl program.
733
734=item comppadlist
735
736Returns the AV object (i.e. in class B::AV) of the global comppadlist.
737
738=item sv_undef
739
740Returns the SV object corresponding to the C variable C<sv_undef>.
741
742=item sv_yes
743
744Returns the SV object corresponding to the C variable C<sv_yes>.
745
746=item sv_no
747
748Returns the SV object corresponding to the C variable C<sv_no>.
749
750=item walkoptree(OP, METHOD)
751
752Does a tree-walk of the syntax tree based at OP and calls METHOD on
753each op it visits. Each node is visited before its children. If
754C<walkoptree_debug> (q.v.) has been called to turn debugging on then
755the method C<walkoptree_debug> is called on each op before METHOD is
756called.
757
758=item walkoptree_debug(DEBUG)
759
760Returns the current debugging flag for C<walkoptree>. If the optional
761DEBUG argument is non-zero, it sets the debugging flag to that. See
762the description of C<walkoptree> above for what the debugging flag
763does.
764
765=item walksymtable(SYMREF, METHOD, RECURSE)
766
767Walk the symbol table starting at SYMREF and call METHOD on each
768symbol visited. When the walk reached package symbols "Foo::" it
769invokes RECURSE and only recurses into the package if that sub
770returns true.
771
772=item svref_2object(SV)
773
774Takes any Perl variable and turns it into an object in the
775appropriate B::OP-derived or B::SV-derived class. Apart from functions
776such as C<main_root>, this is the primary way to get an initial
777"handle" on a internal perl data structure which can then be followed
778with the other access methods.
779
780=item ppname(OPNUM)
781
782Return the PP function name (e.g. "pp_add") of op number OPNUM.
783
784=item hash(STR)
785
786Returns a string in the form "0x..." representing the value of the
787internal hash function used by perl on string STR.
788
789=item cast_I32(I)
790
791Casts I to the internal I32 type used by that perl.
792
793
794=item minus_c
795
796Does the equivalent of the C<-c> command-line option. Obviously, this
797is only useful in a BEGIN block or else the flag is set too late.
798
799
800=item cstring(STR)
801
802Returns a double-quote-surrounded escaped version of STR which can
803be used as a string in C source code.
804
805=item class(OBJ)
806
807Returns the class of an object without the part of the classname
808preceding the first "::". This is used to turn "B::UNOP" into
809"UNOP" for example.
810
811=item threadsv_names
812
813In a perl compiled for threads, this returns a list of the special
814per-thread threadsv variables.
815
816=item byteload_fh(FILEHANDLE)
817
818Load the contents of FILEHANDLE as bytecode. See documentation for
819the B<Bytecode> module in F<B::Backend> for how to generate bytecode.
820
821=back
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822
823=head1 AUTHOR
824
825Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>
826
827=cut