This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
regcomp.sym: Make adjacent opcodes for 2 similar regnodes
[perl5.git] / pod / perldebguts.pod
CommitLineData
055fd3a9
GS
1=head1 NAME
2
3perldebguts - Guts of Perl debugging
4
5=head1 DESCRIPTION
6
ba555bf5 7This is not L<perldebug>, which tells you how to use
74410c12
JM
8the debugger. This manpage describes low-level details concerning
9the debugger's internals, which range from difficult to impossible
10to understand for anyone who isn't incredibly intimate with Perl's guts.
11Caveat lector.
055fd3a9
GS
12
13=head1 Debugger Internals
14
15Perl has special debugging hooks at compile-time and run-time used
16to create debugging environments. These hooks are not to be confused
028611fa
DB
17with the I<perl -Dxxx> command described in L<perlrun|perlrun/-Dletters>,
18which is usable only if a special Perl is built per the instructions in
19the F<INSTALL> podpage in the Perl source tree.
055fd3a9
GS
20
21For example, whenever you call Perl's built-in C<caller> function
74410c12
JM
22from the package C<DB>, the arguments that the corresponding stack
23frame was called with are copied to the C<@DB::args> array. These
24mechanisms are enabled by calling Perl with the B<-d> switch.
25Specifically, the following additional features are enabled
26(cf. L<perlvar/$^P>):
055fd3a9 27
13a2d996 28=over 4
055fd3a9
GS
29
30=item *
31
32Perl inserts the contents of C<$ENV{PERL5DB}> (or C<BEGIN {require
33'perl5db.pl'}> if not present) before the first line of your program.
34
35=item *
36
aa0b556f 37Each array C<@{"_<$filename"}> holds the lines of $filename for a
74410c12
JM
38file compiled by Perl. The same is also true for C<eval>ed strings
39that contain subroutines, or which are currently being executed.
40The $filename for C<eval>ed strings looks like C<(eval 34)>.
8894c26d
MJD
41
42Values in this array are magical in numeric context: they compare
43equal to zero only if the line is not breakable.
055fd3a9
GS
44
45=item *
46
aa0b556f 47Each hash C<%{"_<$filename"}> contains breakpoints and actions keyed
055fd3a9
GS
48by line number. Individual entries (as opposed to the whole hash)
49are settable. Perl only cares about Boolean true here, although
50the values used by F<perl5db.pl> have the form
8894c26d 51C<"$break_condition\0$action">.
055fd3a9
GS
52
53The same holds for evaluated strings that contain subroutines, or
54which are currently being executed. The $filename for C<eval>ed strings
d24ca0c5 55looks like C<(eval 34)>.
055fd3a9
GS
56
57=item *
58
6e764e36 59Each scalar C<${"_<$filename"}> contains C<$filename>. This is
055fd3a9 60also the case for evaluated strings that contain subroutines, or
6e764e36 61which are currently being executed. The C<$filename> for C<eval>ed
d24ca0c5 62strings looks like C<(eval 34)>.
055fd3a9
GS
63
64=item *
65
66After each C<require>d file is compiled, but before it is executed,
67C<DB::postponed(*{"_<$filename"})> is called if the subroutine
68C<DB::postponed> exists. Here, the $filename is the expanded name of
69the C<require>d file, as found in the values of %INC.
70
71=item *
72
73After each subroutine C<subname> is compiled, the existence of
74C<$DB::postponed{subname}> is checked. If this key exists,
75C<DB::postponed(subname)> is called if the C<DB::postponed> subroutine
76also exists.
77
78=item *
79
80A hash C<%DB::sub> is maintained, whose keys are subroutine names
81and whose values have the form C<filename:startline-endline>.
82C<filename> has the form C<(eval 34)> for subroutines defined inside
d24ca0c5 83C<eval>s.
055fd3a9
GS
84
85=item *
86
87When the execution of your program reaches a point that can hold a
74410c12
JM
88breakpoint, the C<DB::DB()> subroutine is called if any of the variables
89C<$DB::trace>, C<$DB::single>, or C<$DB::signal> is true. These variables
055fd3a9
GS
90are not C<local>izable. This feature is disabled when executing
91inside C<DB::DB()>, including functions called from it
92unless C<< $^D & (1<<30) >> is true.
93
94=item *
95
96When execution of the program reaches a subroutine call, a call to
5109e49f
Z
97C<&DB::sub>(I<args>) is made instead, with C<$DB::sub> set to identify
98the called subroutine. (This doesn't happen if the calling subroutine
99was compiled in the C<DB> package.) C<$DB::sub> normally holds the name
100of the called subroutine, if it has a name by which it can be looked up.
101Failing that, C<$DB::sub> will hold a reference to the called subroutine.
102Either way, the C<&DB::sub> subroutine can use C<$DB::sub> as a reference
103by which to call the called subroutine, which it will normally want to do.
055fd3a9 104
77e42cd2
TC
105X<&DB::lsub>If the call is to an lvalue subroutine, and C<&DB::lsub>
106is defined C<&DB::lsub>(I<args>) is called instead, otherwise falling
107back to C<&DB::sub>(I<args>).
108
261cbad1
TC
109=item *
110
5109e49f
Z
111When execution of the program uses C<goto> to enter a non-XS subroutine
112and the 0x80 bit is set in C<$^P>, a call to C<&DB::goto> is made, with
113C<$DB::sub> set to identify the subroutine being entered. The call to
114C<&DB::goto> does not replace the C<goto>; the requested subroutine will
115still be entered once C<&DB::goto> has returned. C<$DB::sub> normally
116holds the name of the subroutine being entered, if it has one. Failing
117that, C<$DB::sub> will hold a reference to the subroutine being entered.
118Unlike when C<&DB::sub> is called, it is not guaranteed that C<$DB::sub>
119can be used as a reference to operate on the subroutine being entered.
261cbad1 120
055fd3a9
GS
121=back
122
123Note that if C<&DB::sub> needs external data for it to work, no
74410c12
JM
124subroutine call is possible without it. As an example, the standard
125debugger's C<&DB::sub> depends on the C<$DB::deep> variable
126(it defines how many levels of recursion deep into the debugger you can go
127before a mandatory break). If C<$DB::deep> is not defined, subroutine
128calls are not possible, even though C<&DB::sub> exists.
055fd3a9
GS
129
130=head2 Writing Your Own Debugger
131
74410c12 132=head3 Environment Variables
666f95b9 133
74410c12
JM
134The C<PERL5DB> environment variable can be used to define a debugger.
135For example, the minimal "working" debugger (it actually doesn't do anything)
136consists of one line:
666f95b9 137
055fd3a9
GS
138 sub DB::DB {}
139
74410c12 140It can easily be defined like this:
666f95b9 141
055fd3a9
GS
142 $ PERL5DB="sub DB::DB {}" perl -d your-script
143
74410c12 144Another brief debugger, slightly more useful, can be created
055fd3a9
GS
145with only the line:
146
147 sub DB::DB {print ++$i; scalar <STDIN>}
148
74410c12
JM
149This debugger prints a number which increments for each statement
150encountered and waits for you to hit a newline before continuing
151to the next statement.
666f95b9 152
74410c12 153The following debugger is actually useful:
666f95b9 154
055fd3a9
GS
155 {
156 package DB;
157 sub DB {}
158 sub sub {print ++$i, " $sub\n"; &$sub}
159 }
160
74410c12
JM
161It prints the sequence number of each subroutine call and the name of the
162called subroutine. Note that C<&DB::sub> is being compiled into the
163package C<DB> through the use of the C<package> directive.
055fd3a9 164
74410c12
JM
165When it starts, the debugger reads your rc file (F<./.perldb> or
166F<~/.perldb> under Unix), which can set important options.
167(A subroutine (C<&afterinit>) can be defined here as well; it is executed
168after the debugger completes its own initialization.)
055fd3a9
GS
169
170After the rc file is read, the debugger reads the PERLDB_OPTS
74410c12
JM
171environment variable and uses it to set debugger options. The
172contents of this variable are treated as if they were the argument
96090e4f 173of an C<o ...> debugger command (q.v. in L<perldebug/"Configurable Options">).
74410c12 174
7b406369 175=head3 Debugger Internal Variables
25cf7dea 176
74410c12
JM
177In addition to the file and subroutine-related variables mentioned above,
178the debugger also maintains various magical internal variables.
179
180=over 4
181
182=item *
055fd3a9 183
74410c12
JM
184C<@DB::dbline> is an alias for C<@{"::_<current_file"}>, which
185holds the lines of the currently-selected file (compiled by Perl), either
186explicitly chosen with the debugger's C<f> command, or implicitly by flow
187of execution.
188
189Values in this array are magical in numeric context: they compare
190equal to zero only if the line is not breakable.
191
192=item *
193
7b406369 194C<%DB::dbline> is an alias for C<%{"::_<current_file"}>, which
74410c12
JM
195contains breakpoints and actions keyed by line number in
196the currently-selected file, either explicitly chosen with the
055fd3a9
GS
197debugger's C<f> command, or implicitly by flow of execution.
198
74410c12
JM
199As previously noted, individual entries (as opposed to the whole hash)
200are settable. Perl only cares about Boolean true here, although
201the values used by F<perl5db.pl> have the form
202C<"$break_condition\0$action">.
203
204=back
205
7b406369 206=head3 Debugger Customization Functions
74410c12
JM
207
208Some functions are provided to simplify customization.
209
210=over 4
211
212=item *
213
71110851
RGS
214See L<perldebug/"Configurable Options"> for a description of options parsed by
215C<DB::parse_options(string)>.
74410c12
JM
216
217=item *
218
219C<DB::dump_trace(skip[,count])> skips the specified number of frames
220and returns a list containing information about the calling frames (all
221of them, if C<count> is missing). Each entry is reference to a hash
222with keys C<context> (either C<.>, C<$>, or C<@>), C<sub> (subroutine
055fd3a9
GS
223name, or info about C<eval>), C<args> (C<undef> or a reference to
224an array), C<file>, and C<line>.
225
74410c12
JM
226=item *
227
228C<DB::print_trace(FH, skip[, count[, short]])> prints
055fd3a9
GS
229formatted info about caller frames. The last two functions may be
230convenient as arguments to C<< < >>, C<< << >> commands.
231
74410c12
JM
232=back
233
055fd3a9
GS
234Note that any variables and functions that are not documented in
235this manpages (or in L<perldebug>) are considered for internal
236use only, and as such are subject to change without notice.
237
238=head1 Frame Listing Output Examples
239
240The C<frame> option can be used to control the output of frame
241information. For example, contrast this expression trace:
242
243 $ perl -de 42
244 Stack dump during die enabled outside of evals.
245
246 Loading DB routines from perl5db.pl patch level 0.94
247 Emacs support available.
248
ccf3535a 249 Enter h or 'h h' for help.
055fd3a9
GS
250
251 main::(-e:1): 0
252 DB<1> sub foo { 14 }
253
254 DB<2> sub bar { 3 }
255
256 DB<3> t print foo() * bar()
257 main::((eval 172):3): print foo() + bar();
258 main::foo((eval 168):2):
259 main::bar((eval 170):2):
260 42
261
492652be 262with this one, once the C<o>ption C<frame=2> has been set:
055fd3a9 263
492652be 264 DB<4> o f=2
055fd3a9
GS
265 frame = '2'
266 DB<5> t print foo() * bar()
267 3: foo() * bar()
268 entering main::foo
269 2: sub foo { 14 };
270 exited main::foo
271 entering main::bar
272 2: sub bar { 3 };
273 exited main::bar
274 42
275
276By way of demonstration, we present below a laborious listing
277resulting from setting your C<PERLDB_OPTS> environment variable to
278the value C<f=n N>, and running I<perl -d -V> from the command line.
7b406369
FC
279Examples using various values of C<n> are shown to give you a feel
280for the difference between settings. Long though it may be, this
055fd3a9
GS
281is not a complete listing, but only excerpts.
282
283=over 4
284
285=item 1
286
f185f654
KW
287 entering main::BEGIN
288 entering Config::BEGIN
289 Package lib/Exporter.pm.
290 Package lib/Carp.pm.
291 Package lib/Config.pm.
292 entering Config::TIEHASH
293 entering Exporter::import
294 entering Exporter::export
295 entering Config::myconfig
296 entering Config::FETCH
297 entering Config::FETCH
298 entering Config::FETCH
299 entering Config::FETCH
055fd3a9
GS
300
301=item 2
302
f185f654
KW
303 entering main::BEGIN
304 entering Config::BEGIN
305 Package lib/Exporter.pm.
306 Package lib/Carp.pm.
307 exited Config::BEGIN
308 Package lib/Config.pm.
309 entering Config::TIEHASH
310 exited Config::TIEHASH
311 entering Exporter::import
312 entering Exporter::export
313 exited Exporter::export
314 exited Exporter::import
315 exited main::BEGIN
316 entering Config::myconfig
317 entering Config::FETCH
318 exited Config::FETCH
319 entering Config::FETCH
320 exited Config::FETCH
321 entering Config::FETCH
055fd3a9 322
d5e42f17 323=item 3
055fd3a9 324
f185f654
KW
325 in $=main::BEGIN() from /dev/null:0
326 in $=Config::BEGIN() from lib/Config.pm:2
327 Package lib/Exporter.pm.
328 Package lib/Carp.pm.
329 Package lib/Config.pm.
330 in $=Config::TIEHASH('Config') from lib/Config.pm:644
331 in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
332 in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from li
333 in @=Config::myconfig() from /dev/null:0
334 in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
335 in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
336 in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
337 in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574
338 in $=Config::FETCH(ref(Config), 'osname') from lib/Config.pm:574
339 in $=Config::FETCH(ref(Config), 'osvers') from lib/Config.pm:574
055fd3a9 340
d5e42f17 341=item 4
055fd3a9 342
f185f654
KW
343 in $=main::BEGIN() from /dev/null:0
344 in $=Config::BEGIN() from lib/Config.pm:2
345 Package lib/Exporter.pm.
346 Package lib/Carp.pm.
347 out $=Config::BEGIN() from lib/Config.pm:0
348 Package lib/Config.pm.
349 in $=Config::TIEHASH('Config') from lib/Config.pm:644
350 out $=Config::TIEHASH('Config') from lib/Config.pm:644
351 in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
352 in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/
353 out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/
354 out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
355 out $=main::BEGIN() from /dev/null:0
356 in @=Config::myconfig() from /dev/null:0
357 in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
358 out $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574
359 in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
360 out $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574
361 in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
362 out $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574
363 in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574
055fd3a9 364
d5e42f17 365=item 5
055fd3a9 366
f185f654
KW
367 in $=main::BEGIN() from /dev/null:0
368 in $=Config::BEGIN() from lib/Config.pm:2
369 Package lib/Exporter.pm.
370 Package lib/Carp.pm.
371 out $=Config::BEGIN() from lib/Config.pm:0
372 Package lib/Config.pm.
373 in $=Config::TIEHASH('Config') from lib/Config.pm:644
374 out $=Config::TIEHASH('Config') from lib/Config.pm:644
375 in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
376 in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E
377 out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E
378 out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
379 out $=main::BEGIN() from /dev/null:0
380 in @=Config::myconfig() from /dev/null:0
381 in $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574
382 out $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574
383 in $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574
384 out $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574
055fd3a9 385
d5e42f17 386=item 6
055fd3a9 387
f185f654
KW
388 in $=CODE(0x15eca4)() from /dev/null:0
389 in $=CODE(0x182528)() from lib/Config.pm:2
390 Package lib/Exporter.pm.
391 out $=CODE(0x182528)() from lib/Config.pm:0
392 scalar context return from CODE(0x182528): undef
393 Package lib/Config.pm.
394 in $=Config::TIEHASH('Config') from lib/Config.pm:628
395 out $=Config::TIEHASH('Config') from lib/Config.pm:628
396 scalar context return from Config::TIEHASH: empty hash
397 in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
398 in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171
399 out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171
400 scalar context return from Exporter::export: ''
401 out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0
402 scalar context return from Exporter::import: ''
055fd3a9
GS
403
404=back
405
406In all cases shown above, the line indentation shows the call tree.
407If bit 2 of C<frame> is set, a line is printed on exit from a
408subroutine as well. If bit 4 is set, the arguments are printed
409along with the caller info. If bit 8 is set, the arguments are
410printed even if they are tied or references. If bit 16 is set, the
411return value is printed, too.
412
413When a package is compiled, a line like this
414
415 Package lib/Carp.pm.
416
417is printed with proper indentation.
418
7b406369 419=head1 Debugging Regular Expressions
055fd3a9
GS
420
421There are two ways to enable debugging output for regular expressions.
422
423If your perl is compiled with C<-DDEBUGGING>, you may use the
dafb2544
KW
424B<-Dr> flag on the command line, and C<-Drv> for more verbose
425information.
055fd3a9 426
dafb2544 427Otherwise, one can C<use re 'debug'>, which has effects at both
3d71525d
NJ
428compile time and run time. Since Perl 5.9.5, this pragma is lexically
429scoped.
055fd3a9 430
7b406369 431=head2 Compile-time Output
055fd3a9
GS
432
433The debugging output at compile time looks like this:
434
ccf3535a 435 Compiling REx '[bc]d(ef*g)+h[ij]k$'
1c102323
MJD
436 size 45 Got 364 bytes for offset annotations.
437 first at 1
438 rarest char g at 0
439 rarest char d at 0
440 1: ANYOF[bc](12)
441 12: EXACT <d>(14)
442 14: CURLYX[0] {1,32767}(28)
443 16: OPEN1(18)
444 18: EXACT <e>(20)
445 20: STAR(23)
446 21: EXACT <f>(0)
447 23: EXACT <g>(25)
448 25: CLOSE1(27)
449 27: WHILEM[1/1](0)
450 28: NOTHING(29)
451 29: EXACT <h>(31)
452 31: ANYOF[ij](42)
453 42: EXACT <k>(44)
454 44: EOL(45)
455 45: END(0)
ccf3535a
JK
456 anchored 'de' at 1 floating 'gh' at 3..2147483647 (checking floating)
457 stclass 'ANYOF[bc]' minlen 7
1c102323
MJD
458 Offsets: [45]
459 1[4] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 5[1]
460 0[0] 12[1] 0[0] 6[1] 0[0] 7[1] 0[0] 9[1] 8[1] 0[0] 10[1] 0[0]
461 11[1] 0[0] 12[0] 12[0] 13[1] 0[0] 14[4] 0[0] 0[0] 0[0] 0[0]
462 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 18[1] 0[0] 19[1] 20[0]
463 Omitting $` $& $' support.
055fd3a9
GS
464
465The first line shows the pre-compiled form of the regex. The second
466shows the size of the compiled form (in arbitrary units, usually
1c102323
MJD
4674-byte words) and the total number of bytes allocated for the
468offset/length table, usually 4+C<size>*8. The next line shows the
469label I<id> of the first node that does a match.
055fd3a9 470
1c102323
MJD
471The
472
ccf3535a
JK
473 anchored 'de' at 1 floating 'gh' at 3..2147483647 (checking floating)
474 stclass 'ANYOF[bc]' minlen 7
1c102323
MJD
475
476line (split into two lines above) contains optimizer
055fd3a9
GS
477information. In the example shown, the optimizer found that the match
478should contain a substring C<de> at offset 1, plus substring C<gh>
479at some offset between 3 and infinity. Moreover, when checking for
480these substrings (to abandon impossible matches quickly), Perl will check
481for the substring C<gh> before checking for the substring C<de>. The
482optimizer may also use the knowledge that the match starts (at the
1c102323
MJD
483C<first> I<id>) with a character class, and no string
484shorter than 7 characters can possibly match.
055fd3a9 485
1c102323 486The fields of interest which may appear in this line are
055fd3a9 487
13a2d996 488=over 4
055fd3a9
GS
489
490=item C<anchored> I<STRING> C<at> I<POS>
491
492=item C<floating> I<STRING> C<at> I<POS1..POS2>
493
494See above.
495
496=item C<matching floating/anchored>
497
498Which substring to check first.
499
500=item C<minlen>
501
502The minimal length of the match.
503
504=item C<stclass> I<TYPE>
505
506Type of first matching node.
507
508=item C<noscan>
509
510Don't scan for the found substrings.
511
512=item C<isall>
513
1c102323 514Means that the optimizer information is all that the regular
055fd3a9
GS
515expression contains, and thus one does not need to enter the regex engine at
516all.
517
518=item C<GPOS>
519
520Set if the pattern contains C<\G>.
521
522=item C<plus>
523
524Set if the pattern starts with a repeated char (as in C<x+y>).
525
526=item C<implicit>
527
528Set if the pattern starts with C<.*>.
529
530=item C<with eval>
531
532Set if the pattern contain eval-groups, such as C<(?{ code })> and
533C<(??{ code })>.
534
535=item C<anchored(TYPE)>
536
7b406369 537If the pattern may match only at a handful of places, with C<TYPE>
d3d47aac 538being C<SBOL>, C<MBOL>, or C<GPOS>. See the table below.
055fd3a9
GS
539
540=back
541
542If a substring is known to match at end-of-line only, it may be
ccf3535a 543followed by C<$>, as in C<floating 'k'$>.
055fd3a9 544
1c102323
MJD
545The optimizer-specific information is used to avoid entering (a slow) regex
546engine on strings that will not definitely match. If the C<isall> flag
055fd3a9
GS
547is set, a call to the regex engine may be avoided even when the optimizer
548found an appropriate place for the match.
549
1c102323 550Above the optimizer section is the list of I<nodes> of the compiled
055fd3a9
GS
551form of the regex. Each line has format
552
553C< >I<id>: I<TYPE> I<OPTIONAL-INFO> (I<next-id>)
554
7b406369 555=head2 Types of Nodes
055fd3a9 556
78465a4b 557Here are the current possible types, with short descriptions:
055fd3a9 558
65aa4ca7
FC
559=for comment
560This table is generated by regen/regcomp.pl. Any changes made here
561will be lost.
562
563=for regcomp.pl begin
564
e21ef692 565 # TYPE arg-description [regnode-struct-suffix] [longjump-len] DESCRIPTION
5da6b59a
KW
566
567 # Exit points
65aa4ca7 568
89829bb5
KW
569 END no End of program.
570 SUCCEED no Return from a subroutine, basically.
5da6b59a 571
d3d47aac 572 # Line Start Anchors:
89829bb5
KW
573 SBOL no Match "" at beginning of line: /^/, /\A/
574 MBOL no Same, assuming multiline: /^/m
5da6b59a 575
d3d47aac 576 # Line End Anchors:
89829bb5
KW
577 SEOL no Match "" at end of line: /$/
578 MEOL no Same, assuming multiline: /$/m
579 EOS no Match "" at end of string: /\z/
d3d47aac
YO
580
581 # Match Start Anchors:
89829bb5 582 GPOS no Matches where last m//g left off.
d3d47aac
YO
583
584 # Word Boundary Opcodes:
0991ffc9
KW
585 BOUND no Like BOUNDA for non-utf8, otherwise like
586 BOUNDU
89829bb5
KW
587 BOUNDL no Like BOUND/BOUNDU, but \w and \W are
588 defined by current locale
589 BOUNDU no Match "" at any boundary of a given type
912b808c 590 using /u rules.
89829bb5
KW
591 BOUNDA no Match "" at any boundary between \w\W or
592 \W\w, where \w is [_a-zA-Z0-9]
0991ffc9
KW
593 NBOUND no Like NBOUNDA for non-utf8, otherwise like
594 BOUNDU
89829bb5
KW
595 NBOUNDL no Like NBOUND/NBOUNDU, but \w and \W are
596 defined by current locale
597 NBOUNDU no Match "" at any non-boundary of a given
912b808c 598 type using using /u rules.
89829bb5
KW
599 NBOUNDA no Match "" betweeen any \w\w or \W\W, where
600 \w is [_a-zA-Z0-9]
5da6b59a
KW
601
602 # [Special] alternatives:
89829bb5
KW
603 REG_ANY no Match any one character (except newline).
604 SANY no Match any one character.
46fc0c43
KW
605 ANYOF sv Match character in (or not in) this class,
606 charclass single char match only
607 ANYOFD sv Like ANYOF, but /d is in effect
608 charclass
609 ANYOFL sv Like ANYOF, but /l is in effect
610 charclass
611 ANYOFPOSIXL sv Like ANYOFL, but matches [[:posix:]]
612 charclass_ classes
613 posixl
f6eaa562 614
c316b824 615 ANYOFH sv 1 Like ANYOF, but only has "High" matches,
29a889ef
KW
616 none in the bitmap; the flags field
617 contains the lowest matchable UTF-8 start
618 byte
6966a05b 619 ANYOFHb sv 1 Like ANYOFH, but all matches share the same
a5bc0742 620 UTF-8 start byte, given in the flags field
3146c00a
KW
621 ANYOFHr sv 1 Like ANYOFH, but the flags field contains
622 packed bounds for all matchable UTF-8 start
623 bytes.
53d42e43 624 ANYOFHs sv 1 Like ANYOFHb, but has a string field that
34924db0
KW
625 gives the leading matchable UTF-8 bytes;
626 flags field is len
13fcf652
KW
627 ANYOFR packed 1 Matches any character in the range given by
628 its packed args: upper 12 bits is the max
629 delta from the base lower 20; the flags
630 field contains the lowest matchable UTF-8
631 start byte
2d5613be
KW
632 ANYOFRb packed 1 Like ANYOFR, but all matches share the same
633 UTF-8 start byte, given in the flags field
f6eaa562 634
89829bb5
KW
635 ANYOFM byte 1 Like ANYOF, but matches an invariant byte
636 as determined by the mask and arg
3db0bccc 637 NANYOFM byte 1 complement of ANYOFM
7bc66b18 638
d3d47aac 639 # POSIX Character Classes:
89829bb5
KW
640 POSIXD none Some [[:class:]] under /d; the FLAGS field
641 gives which one
642 POSIXL none Some [[:class:]] under /l; the FLAGS field
643 gives which one
644 POSIXU none Some [[:class:]] under /u; the FLAGS field
645 gives which one
646 POSIXA none Some [[:class:]] under /a; the FLAGS field
647 gives which one
648 NPOSIXD none complement of POSIXD, [[:^class:]]
649 NPOSIXL none complement of POSIXL, [[:^class:]]
650 NPOSIXU none complement of POSIXU, [[:^class:]]
651 NPOSIXA none complement of POSIXA, [[:^class:]]
652
89829bb5
KW
653 CLUMP no Match any extended grapheme cluster
654 sequence
5da6b59a
KW
655
656 # Alternation
657
65aa4ca7
FC
658 # BRANCH The set of branches constituting a single choice are
659 # hooked together with their "next" pointers, since
660 # precedence prevents anything being concatenated to
661 # any individual branch. The "next" pointer of the last
662 # BRANCH in a choice points to the thing following the
663 # whole choice. This is also where the final "next"
664 # pointer of each individual branch points; each branch
665 # starts with the operand node of a BRANCH node.
5da6b59a 666 #
89829bb5 667 BRANCH node Match this alternative, or the next...
5da6b59a 668
5da6b59a
KW
669 # Literals
670
3ace85ea
KW
671 EXACT str Match this string (flags field is the
672 length).
ae06e581
KW
673
674 # In a long string node, the U32 argument is the length, and is
675 # immediately followed by the string.
676 LEXACT len:str 1 Match this long string (preceded by length;
677 flags unused).
89829bb5 678 EXACTL str Like EXACT, but /l is in effect (used so
58ea1df2 679 locale-related warnings can be checked for)
a2f213ef 680 EXACTF str Like EXACT, but match using /id rules;
58ea1df2
KW
681 (string not UTF-8, ASCII folded; non-ASCII
682 not)
a2f213ef 683 EXACTFL str Like EXACT, but match using /il rules;
58ea1df2 684 (string not likely to be folded)
a2f213ef 685 EXACTFU str Like EXACT, but match using /iu rules;
58ea1df2
KW
686 (string folded)
687
a2f213ef 688 EXACTFAA str Like EXACT, but match using /iaa rules;
5f162c35
KW
689 (string folded except MICRO in non-UTF8
690 patterns; doesn't contain SHARP S unless
691 UTF-8; folded length <= unfolded)
f97d9711
KW
692 EXACTFAA_NO_TRIE str Like EXACTFAA, (string not UTF-8, folded
693 except: MICRO, SHARP S; folded length <=
694 unfolded, not currently trie-able)
a2f213ef
KW
695
696 EXACTFUP str Like EXACT, but match using /iu rules;
5f162c35
KW
697 (string not UTF-8, folded except MICRO:
698 hence Problematic)
aa419ff3 699
a2f213ef
KW
700 EXACTFLU8 str Like EXACTFU, but use /il, UTF-8, (string
701 is folded, and everything in it is above
58ea1df2 702 255
4f4c2c24 703
3f2416ae 704 EXACT_REQ8 str Like EXACT, but only UTF-8 encoded targets
4f4c2c24 705 can match
3f2416ae 706 LEXACT_REQ8 len:str 1 Like LEXACT, but only UTF-8 encoded targets
5cd61b66 707 can match
3f2416ae 708 EXACTFU_REQ8 str Like EXACTFU, but only UTF-8 encoded
4f4c2c24 709 targets can match
f6b4b99d 710
95fb0a6e
KW
711 EXACTFU_S_EDGE str /di rules, but nothing in it precludes /ui,
712 except begins and/or ends with [Ss];
58ea1df2 713 (string not UTF-8; compile-time only)
8a100c91 714
7af55186
KW
715 # New charclass like patterns
716 LNBREAK none generic newline pattern
717
718 # Trie Related
719
720 # Behave the same as A|LIST|OF|WORDS would. The '..C' variants
721 # have inline charclass data (ascii only), the 'C' store it in the
722 # structure.
723
724 TRIE trie 1 Match many EXACT(F[ALU]?)? at once.
725 flags==type
726 TRIEC trie Same as TRIE, but with embedded charclass
727 charclass data
728
729 AHOCORASICK trie 1 Aho Corasick stclass. flags==type
730 AHOCORASICKC trie Same as AHOCORASICK, but with embedded
731 charclass charclass data
732
5da6b59a
KW
733 # Do nothing types
734
89829bb5 735 NOTHING no Match empty string.
5da6b59a 736 # A variant of above which delimits a group, thus stops optimizations
89829bb5
KW
737 TAIL no Match empty string. Can jump here from
738 outside.
5da6b59a
KW
739
740 # Loops
741
65aa4ca7 742 # STAR,PLUS '?', and complex '*' and '+', are implemented as
62e6ef33 743 # circular BRANCH structures. Simple cases
65aa4ca7
FC
744 # (one character per match) are implemented with STAR
745 # and PLUS for speed and to minimize recursive plunges.
5da6b59a 746 #
89829bb5
KW
747 STAR node Match this (simple) thing 0 or more times.
748 PLUS node Match this (simple) thing 1 or more times.
7bc66b18 749
89829bb5
KW
750 CURLY sv 2 Match this simple thing {n,m} times.
751 CURLYN no 2 Capture next-after-this simple thing
752 CURLYM no 2 Capture this medium-complex thing {n,m}
753 times.
754 CURLYX sv 2 Match this complex thing {n,m} times.
5da6b59a
KW
755
756 # This terminator creates a loop structure for CURLYX
89829bb5
KW
757 WHILEM no Do curly processing and see if rest
758 matches.
5da6b59a
KW
759
760 # Buffer related
761
762 # OPEN,CLOSE,GROUPP ...are numbered at compile time.
89829bb5
KW
763 OPEN num 1 Mark this point in input as start of #n.
764 CLOSE num 1 Close corresponding OPEN of #n.
765 SROPEN none Same as OPEN, but for script run
766 SRCLOSE none Close preceding SROPEN
767
768 REF num 1 Match some already matched string
912b808c
KW
769 REFF num 1 Match already matched string, using /di
770 rules.
771 REFFL num 1 Match already matched string, using /li
772 rules.
773 REFFU num 1 Match already matched string, usng /ui.
774 REFFA num 1 Match already matched string, using /aai
775 rules.
65aa4ca7
FC
776
777 # Named references. Code in regcomp.c assumes that these all are after
778 # the numbered references
016b7209
KW
779 REFN no-sv 1 Match some already matched string
780 REFFN no-sv 1 Match already matched string, using /di
912b808c 781 rules.
016b7209 782 REFFLN no-sv 1 Match already matched string, using /li
912b808c 783 rules.
016b7209 784 REFFUN num 1 Match already matched string, using /ui
912b808c 785 rules.
016b7209 786 REFFAN num 1 Match already matched string, using /aai
912b808c 787 rules.
7bc66b18 788
d3d47aac 789 # Support for long RE
89829bb5
KW
790 LONGJMP off 1 1 Jump far away.
791 BRANCHJ off 1 1 BRANCH with long offset.
d3d47aac
YO
792
793 # Special Case Regops
80101a2c 794 IFMATCH off 1 1 Succeeds if the following matches; non-zero
2abbd513
KW
795 flags "f", next_off "o" means lookbehind
796 assertion starting "f..(f-o)" characters
797 before current
80101a2c 798 UNLESSM off 1 1 Fails if the following matches; non-zero
2abbd513
KW
799 flags "f", next_off "o" means lookbehind
800 assertion starting "f..(f-o)" characters
801 before current
89829bb5
KW
802 SUSPEND off 1 1 "Independent" sub-RE.
803 IFTHEN off 1 1 Switch, should be preceded by switcher.
804 GROUPP num 1 Whether the group matched.
5da6b59a 805
5da6b59a
KW
806 # The heavy worker
807
89829bb5
KW
808 EVAL evl/flags Execute some Perl code.
809 2L
5da6b59a
KW
810
811 # Modifiers
812
89829bb5
KW
813 MINMOD no Next operator is not greedy.
814 LOGICAL no Next opcode should set the flag only.
5da6b59a
KW
815
816 # This is not used yet
89829bb5 817 RENUM off 1 1 Group with independently numbered parens.
5da6b59a 818
5da6b59a 819 # Regex Subroutines
89829bb5 820 GOSUB num/ofs 2L recurse to paren arg1 at (signed) ofs arg2
5da6b59a
KW
821
822 # Special conditionals
016b7209 823 GROUPPN no-sv 1 Whether the group matched.
89829bb5
KW
824 INSUBP num 1 Whether we are in a specific recurse.
825 DEFINEP none 1 Never execute directly.
5da6b59a
KW
826
827 # Backtracking Verbs
89829bb5
KW
828 ENDLIKE none Used only for the type field of verbs
829 OPFAIL no-sv 1 Same as (?!), but with verb arg
830 ACCEPT no-sv/num Accepts the current matched string, with
831 2L verbar
5da6b59a
KW
832
833 # Verbs With Arguments
89829bb5
KW
834 VERB no-sv 1 Used only for the type field of verbs
835 PRUNE no-sv 1 Pattern fails at this startpoint if no-
836 backtracking through this
837 MARKPOINT no-sv 1 Push the current location for rollback by
838 cut.
839 SKIP no-sv 1 On failure skip forward (to the mark)
840 before retrying
841 COMMIT no-sv 1 Pattern fails outright if backtracking
842 through this
843 CUTGROUP no-sv 1 On failure go to the next alternation in
844 the group
5da6b59a
KW
845
846 # Control what to keep in $&.
89829bb5 847 KEEPS no $& begins here.
5da6b59a 848
5da6b59a
KW
849 # SPECIAL REGOPS
850
65aa4ca7
FC
851 # This is not really a node, but an optimized away piece of a "long"
852 # node. To simplify debugging output, we mark it as if it were a node
89829bb5 853 OPTIMIZED off Placeholder for dump.
5da6b59a
KW
854
855 # Special opcode with the property that no opcode in a compiled program
856 # will ever be of this type. Thus it can be used as a flag value that
857 # no other opcode has been seen. END is used similarly, in that an END
65aa4ca7
FC
858 # node cant be optimized. So END implies "unoptimizable" and PSEUDO
859 # mean "not seen anything to optimize yet".
89829bb5 860 PSEUDO off Pseudo opcode for internal use.
65aa4ca7 861
86451f01
KW
862 REGEX_SET depth p Regex set, temporary node used in pre-
863 optimization compilation
864
65aa4ca7 865=for regcomp.pl end
055fd3a9 866
1c102323
MJD
867=for unprinted-credits
868Next section M-J. Dominus (mjd-perl-patch+@plover.com) 20010421
869
870Following the optimizer information is a dump of the offset/length
871table, here split across several lines:
872
873 Offsets: [45]
874 1[4] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 5[1]
875 0[0] 12[1] 0[0] 6[1] 0[0] 7[1] 0[0] 9[1] 8[1] 0[0] 10[1] 0[0]
876 11[1] 0[0] 12[0] 12[0] 13[1] 0[0] 14[4] 0[0] 0[0] 0[0] 0[0]
877 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 18[1] 0[0] 19[1] 20[0]
878
879The first line here indicates that the offset/length table contains 45
880entries. Each entry is a pair of integers, denoted by C<offset[length]>.
17c338f3 881Entries are numbered starting with 1, so entry #1 here is C<1[4]> and
1c102323
MJD
882entry #12 is C<5[1]>. C<1[4]> indicates that the node labeled C<1:>
883(the C<1: ANYOF[bc]>) begins at character position 1 in the
884pre-compiled form of the regex, and has a length of 4 characters.
885C<5[1]> in position 12
886indicates that the node labeled C<12:>
887(the C<< 12: EXACT <d> >>) begins at character position 5 in the
888pre-compiled form of the regex, and has a length of 1 character.
889C<12[1]> in position 14
890indicates that the node labeled C<14:>
891(the C<< 14: CURLYX[0] {1,32767} >>) begins at character position 12 in the
892pre-compiled form of the regex, and has a length of 1 character---that
893is, it corresponds to the C<+> symbol in the precompiled regex.
894
895C<0[0]> items indicate that there is no corresponding node.
896
7b406369 897=head2 Run-time Output
055fd3a9
GS
898
899First of all, when doing a match, one may get no run-time output even
900if debugging is enabled. This means that the regex engine was never
901entered and that all of the job was therefore done by the optimizer.
902
903If the regex engine was entered, the output may look like this:
904
ccf3535a 905 Matching '[bc]d(ef*g)+h[ij]k$' against 'abcdefg__gh__'
055fd3a9
GS
906 Setting an EVAL scope, savestack=3
907 2 <ab> <cdefg__gh_> | 1: ANYOF
908 3 <abc> <defg__gh_> | 11: EXACT <d>
909 4 <abcd> <efg__gh_> | 13: CURLYX {1,32767}
910 4 <abcd> <efg__gh_> | 26: WHILEM
911 0 out of 1..32767 cc=effff31c
912 4 <abcd> <efg__gh_> | 15: OPEN1
913 4 <abcd> <efg__gh_> | 17: EXACT <e>
914 5 <abcde> <fg__gh_> | 19: STAR
915 EXACT <f> can match 1 times out of 32767...
916 Setting an EVAL scope, savestack=3
917 6 <bcdef> <g__gh__> | 22: EXACT <g>
918 7 <bcdefg> <__gh__> | 24: CLOSE1
919 7 <bcdefg> <__gh__> | 26: WHILEM
920 1 out of 1..32767 cc=effff31c
921 Setting an EVAL scope, savestack=12
922 7 <bcdefg> <__gh__> | 15: OPEN1
923 7 <bcdefg> <__gh__> | 17: EXACT <e>
924 restoring \1 to 4(4)..7
925 failed, try continuation...
926 7 <bcdefg> <__gh__> | 27: NOTHING
927 7 <bcdefg> <__gh__> | 28: EXACT <h>
928 failed...
929 failed...
930
931The most significant information in the output is about the particular I<node>
932of the compiled regex that is currently being tested against the target string.
933The format of these lines is
934
935C< >I<STRING-OFFSET> <I<PRE-STRING>> <I<POST-STRING>> |I<ID>: I<TYPE>
936
937The I<TYPE> info is indented with respect to the backtracking level.
938Other incidental information appears interspersed within.
939
7b406369 940=head1 Debugging Perl Memory Usage
055fd3a9
GS
941
942Perl is a profligate wastrel when it comes to memory use. There
943is a saying that to estimate memory usage of Perl, assume a reasonable
944algorithm for memory allocation, multiply that estimate by 10, and
945while you still may miss the mark, at least you won't be quite so
4375e838 946astonished. This is not absolutely true, but may provide a good
055fd3a9
GS
947grasp of what happens.
948
949Assume that an integer cannot take less than 20 bytes of memory, a
950float cannot take less than 24 bytes, a string cannot take less
951than 32 bytes (all these examples assume 32-bit architectures, the
952result are quite a bit worse on 64-bit architectures). If a variable
953is accessed in two of three different ways (which require an integer,
954a float, or a string), the memory footprint may increase yet another
b9449ee0 95520 bytes. A sloppy malloc(3) implementation can inflate these
055fd3a9
GS
956numbers dramatically.
957
958On the opposite end of the scale, a declaration like
959
960 sub foo;
961
962may take up to 500 bytes of memory, depending on which release of Perl
963you're running.
964
965Anecdotal estimates of source-to-compiled code bloat suggest an
966eightfold increase. This means that the compiled form of reasonable
967(normally commented, properly indented etc.) code will take
968about eight times more space in memory than the code took
969on disk.
970
b30f304a
JH
971The B<-DL> command-line switch is obsolete since circa Perl 5.6.0
972(it was available only if Perl was built with C<-DDEBUGGING>).
973The switch was used to track Perl's memory allocations and possible
974memory leaks. These days the use of malloc debugging tools like
5b6a3331 975F<Purify> or F<valgrind> is suggested instead. See also
7b406369 976L<perlhacktips/PERL_MEM_LOG>.
b30f304a
JH
977
978One way to find out how much memory is being used by Perl data
979structures is to install the Devel::Size module from CPAN: it gives
980you the minimum number of bytes required to store a particular data
981structure. Please be mindful of the difference between the size()
982and total_size().
983
984If Perl has been compiled using Perl's malloc you can analyze Perl
7b406369 985memory usage by setting $ENV{PERL_DEBUG_MSTATS}.
055fd3a9
GS
986
987=head2 Using C<$ENV{PERL_DEBUG_MSTATS}>
988
989If your perl is using Perl's malloc() and was compiled with the
990necessary switches (this is the default), then it will print memory
4375e838 991usage statistics after compiling your code when C<< $ENV{PERL_DEBUG_MSTATS}
055fd3a9
GS
992> 1 >>, and before termination of the program when C<<
993$ENV{PERL_DEBUG_MSTATS} >= 1 >>. The report format is similar to
994the following example:
995
f185f654
KW
996 $ PERL_DEBUG_MSTATS=2 perl -e "require Carp"
997 Memory allocation statistics after compilation: (buckets 4(4)..8188(8192)
998 14216 free: 130 117 28 7 9 0 2 2 1 0 0
055fd3a9 999 437 61 36 0 5
f185f654 1000 60924 used: 125 137 161 55 7 8 6 16 2 0 1
055fd3a9 1001 74 109 304 84 20
f185f654
KW
1002 Total sbrk(): 77824/21:119. Odd ends: pad+heads+chain+tail: 0+636+0+2048.
1003 Memory allocation statistics after execution: (buckets 4(4)..8188(8192)
1004 30888 free: 245 78 85 13 6 2 1 3 2 0 1
055fd3a9 1005 315 162 39 42 11
f185f654 1006 175816 used: 265 176 1112 111 26 22 11 27 2 1 1
055fd3a9 1007 196 178 1066 798 39
f185f654 1008 Total sbrk(): 215040/47:145. Odd ends: pad+heads+chain+tail: 0+2192+0+6144.
055fd3a9
GS
1009
1010It is possible to ask for such a statistic at arbitrary points in
b9449ee0 1011your execution using the mstat() function out of the standard
055fd3a9
GS
1012Devel::Peek module.
1013
1014Here is some explanation of that format:
1015
13a2d996 1016=over 4
055fd3a9
GS
1017
1018=item C<buckets SMALLEST(APPROX)..GREATEST(APPROX)>
1019
1020Perl's malloc() uses bucketed allocations. Every request is rounded
1021up to the closest bucket size available, and a bucket is taken from
1022the pool of buckets of that size.
1023
1024The line above describes the limits of buckets currently in use.
1025Each bucket has two sizes: memory footprint and the maximal size
1026of user data that can fit into this bucket. Suppose in the above
1027example that the smallest bucket were size 4. The biggest bucket
1028would have usable size 8188, and the memory footprint would be 8192.
1029
1030In a Perl built for debugging, some buckets may have negative usable
1031size. This means that these buckets cannot (and will not) be used.
1032For larger buckets, the memory footprint may be one page greater
7b406369 1033than a power of 2. If so, the corresponding power of two is
055fd3a9
GS
1034printed in the C<APPROX> field above.
1035
1036=item Free/Used
1037
1038The 1 or 2 rows of numbers following that correspond to the number
1039of buckets of each size between C<SMALLEST> and C<GREATEST>. In
1040the first row, the sizes (memory footprints) of buckets are powers
1041of two--or possibly one page greater. In the second row, if present,
1042the memory footprints of the buckets are between the memory footprints
1043of two buckets "above".
1044
4375e838 1045For example, suppose under the previous example, the memory footprints
055fd3a9
GS
1046were
1047
f185f654 1048 free: 8 16 32 64 128 256 512 1024 2048 4096 8192
055fd3a9
GS
1049 4 12 24 48 80
1050
7b406369 1051With a non-C<DEBUGGING> perl, the buckets starting from C<128> have
d1be9408 1052a 4-byte overhead, and thus an 8192-long bucket may take up to
055fd3a9
GS
10538188-byte allocations.
1054
1055=item C<Total sbrk(): SBRKed/SBRKs:CONTINUOUS>
1056
1057The first two fields give the total amount of memory perl sbrk(2)ed
1058(ess-broken? :-) and number of sbrk(2)s used. The third number is
1059what perl thinks about continuity of returned chunks. So long as
1060this number is positive, malloc() will assume that it is probable
1061that sbrk(2) will provide continuous memory.
1062
1063Memory allocated by external libraries is not counted.
1064
1065=item C<pad: 0>
1066
1067The amount of sbrk(2)ed memory needed to keep buckets aligned.
1068
1069=item C<heads: 2192>
1070
1071Although memory overhead of bigger buckets is kept inside the bucket, for
1072smaller buckets, it is kept in separate areas. This field gives the
1073total size of these areas.
1074
1075=item C<chain: 0>
1076
1077malloc() may want to subdivide a bigger bucket into smaller buckets.
1078If only a part of the deceased bucket is left unsubdivided, the rest
1079is kept as an element of a linked list. This field gives the total
1080size of these chunks.
1081
1082=item C<tail: 6144>
1083
1084To minimize the number of sbrk(2)s, malloc() asks for more memory. This
1085field gives the size of the yet unused part, which is sbrk(2)ed, but
1086never touched.
1087
1088=back
1089
055fd3a9
GS
1090=head1 SEE ALSO
1091
1092L<perldebug>,
65ac759c 1093L<perl5db.pl>,
055fd3a9 1094L<perlguts>,
65ac759c 1095L<perlrun>,
055fd3a9
GS
1096L<re>,
1097and
fe854a6f 1098L<Devel::DProf>.