3 # Copyright (c) 1996, 1997, 1998 Malcolm Beattie
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.
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);
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';
34 @B::IO::ISA = 'B::PVMG';
35 @B::FM::ISA = 'B::CV';
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';
51 @B::SPECIAL::ISA = 'B::OBJECT';
54 # Stop "-w" from complaining about the lack of a real B::OBJECT class
63 my ($class, $value) = @_;
65 walkoptree_debug($value);
69 # add to .xs for perl5.002
79 sub parents { \@parents }
84 return sprintf("%s (0x%x) %s", class($op), $$op, $op->ppaddr);
88 my($op, $method, $level) = @_;
89 $op_count++; # just for statistics
91 warn(sprintf("walkoptree: %d. %s\n", $level, peekop($op))) if $debug;
93 if ($$op && ($op->flags & OPf_KIDS)) {
95 unshift(@parents, $op);
96 for ($kid = $op->first; $$kid; $kid = $kid->sibling) {
97 walkoptree_slow($kid, $method, $level + 1);
104 return "Total number of OPs processed: $op_count\n";
108 my ($sec, $min, $hr) = localtime;
109 my ($user, $sys) = times;
110 sprintf("%02d:%02d:%02d user=$user sys=$sys",
111 $hr, $min, $sec, $user, $sys);
116 my ($obj, $value) = @_;
117 # warn(sprintf("savesym: sym_%x => %s\n", $$obj, $value)); # debug
118 $symtable{sprintf("sym_%x", $$obj)} = $value;
123 return $symtable{sprintf("sym_%x", $$obj)};
126 sub walkoptree_exec {
127 my ($op, $method, $level) = @_;
129 my $prefix = " " x $level;
130 for (; $$op; $op = $op->next) {
133 print $prefix, "goto $sym\n";
136 savesym($op, sprintf("%s (0x%lx)", class($op), $$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;
146 print $prefix, "PMREPLSTART => {\n";
147 walkoptree_exec($pmreplstart, $method, $level + 1);
148 print $prefix, "}\n";
150 } elsif ($ppname eq "pp_substcont") {
151 print $prefix, "SUBSTCONT => {\n";
152 walkoptree_exec($op->other->pmreplstart, $method, $level + 1);
153 print $prefix, "}\n";
155 } elsif ($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 $prefix, "}\n";
162 } elsif ($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;
179 print $prefix, "SUBST => {\n";
180 walkoptree_exec($replstart, $method, $level + 1);
181 print $prefix, "}\n";
188 my ($symref, $method, $recurse, $prefix) = @_;
192 while (($sym, *glob) = each %$symref) {
194 $sym = $prefix . $sym;
195 if ($sym ne "main::" && &$recurse($sym)) {
196 walksymtable(\%glob, $method, $recurse, $sym);
199 svref_2object(\*glob)->EGV->$method();
210 my ($class, $section, $symtable, $default) = @_;
211 $output_fh ||= FileHandle->new_tmpfile;
212 my $obj = bless [-1, $section, $symtable, $default], $class;
213 $sections{$section} = $obj;
218 my ($class, $section) = @_;
219 return $sections{$section};
224 while (defined($_ = shift)) {
225 print $output_fh "$section->[1]\t$_\n";
232 return $section->[0];
237 return $section->[1];
242 return $section->[2];
247 return $section->[3];
251 my ($section, $fh, $format) = @_;
252 my $name = $section->name;
253 my $sym = $section->symtable || {};
254 my $default = $section->default;
256 seek($output_fh, 0, 0);
257 while (<$output_fh>) {
262 exists($sym->{$1}) ? $sym->{$1} : $default;
264 printf $fh $format, $_;
278 B - The Perl Compiler
286 The C<B> module supplies classes which allow a Perl program to delve
287 into its own innards. It is the module used to implement the
288 "backends" of the Perl compiler. Usage of the compiler does not
289 require knowledge of this module: see the F<O> module for the
290 user-visible part. The C<B> module is of use to those who want to
291 write new compiler backends. This documentation assumes that the
292 reader knows a fair amount about perl's internals including such
293 things as SVs, OPs and the internal symbol table and syntax tree
296 =head1 OVERVIEW OF CLASSES
298 The C structures used by Perl's internals to hold SV and OP
299 information (PVIV, AV, HV, ..., OP, SVOP, UNOP, ...) are modelled on a
300 class hierarchy and the C<B> module gives access to them via a true
301 object hierarchy. Structure fields which point to other objects
302 (whether types of SV or types of OP) are represented by the C<B>
303 module as Perl objects of the appropriate class. The bulk of the C<B>
304 module is the methods for accessing fields of these structures. Note
305 that all access is read-only: you cannot modify the internals by
308 =head2 SV-RELATED CLASSES
310 B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM, B::PVLV,
311 B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes correspond in
312 the obvious way to the underlying C structures of similar names. The
313 inheritance hierarchy mimics the underlying C "inheritance". Access
314 methods correspond to the underlying C macros for field access,
315 usually with the leading "class indication" prefix removed (Sv, Av,
316 Hv, ...). The leading prefix is only left in cases where its removal
317 would cause a clash in method name. For example, C<GvREFCNT> stays
318 as-is since its abbreviation would clash with the "superclass" method
319 C<REFCNT> (corresponding to the C function C<SvREFCNT>).
371 =head2 B::PVMG METHODS
381 =head2 B::MAGIC METHODS
399 =head2 B::PVLV METHODS
555 =head2 OP-RELATED CLASSES
557 B::OP, B::UNOP, B::BINOP, B::LOGOP, B::CONDOP, B::LISTOP, B::PMOP,
558 B::SVOP, B::GVOP, B::PVOP, B::CVOP, B::LOOP, B::COP.
559 These classes correspond in
560 the obvious way to the underlying C structures of similar names. The
561 inheritance hierarchy mimics the underlying C "inheritance". Access
562 methods correspond to the underlying C structre field names, with the
563 leading "class indication" prefix removed (op_).
575 This returns the function name as a string (e.g. pp_add, pp_rv2av).
579 This returns the op description from the global C op_desc array
580 (e.g. "addition" "array deref").
594 =head2 B::UNOP METHOD
602 =head2 B::BINOP METHOD
610 =head2 B::LOGOP METHOD
618 =head2 B::CONDOP METHODS
628 =head2 B::LISTOP METHOD
636 =head2 B::PMOP METHODS
656 =head2 B::SVOP METHOD
664 =head2 B::GVOP METHOD
672 =head2 B::PVOP METHOD
680 =head2 B::LOOP METHODS
692 =head2 B::COP METHODS
710 =head1 FUNCTIONS EXPORTED BY C<B>
712 The C<B> module exports a variety of functions: some are simple
713 utility functions, others provide a Perl program with a way to
714 get an initial "handle" on an internal object.
720 Return the (faked) CV corresponding to the main part of the Perl
725 Returns the root op (i.e. an object in the appropriate B::OP-derived
726 class) of the main part of the Perl program.
730 Returns the starting op of the main part of the Perl program.
734 Returns the AV object (i.e. in class B::AV) of the global comppadlist.
738 Returns the SV object corresponding to the C variable C<sv_undef>.
742 Returns the SV object corresponding to the C variable C<sv_yes>.
746 Returns the SV object corresponding to the C variable C<sv_no>.
748 =item walkoptree(OP, METHOD)
750 Does a tree-walk of the syntax tree based at OP and calls METHOD on
751 each op it visits. Each node is visited before its children. If
752 C<walkoptree_debug> (q.v.) has been called to turn debugging on then
753 the method C<walkoptree_debug> is called on each op before METHOD is
756 =item walkoptree_debug(DEBUG)
758 Returns the current debugging flag for C<walkoptree>. If the optional
759 DEBUG argument is non-zero, it sets the debugging flag to that. See
760 the description of C<walkoptree> above for what the debugging flag
763 =item walksymtable(SYMREF, METHOD, RECURSE)
765 Walk the symbol table starting at SYMREF and call METHOD on each
766 symbol visited. When the walk reached package symbols "Foo::" it
767 invokes RECURSE and only recurses into the package if that sub
770 =item svref_2object(SV)
772 Takes any Perl variable and turns it into an object in the
773 appropriate B::OP-derived or B::SV-derived class. Apart from functions
774 such as C<main_root>, this is the primary way to get an initial
775 "handle" on a internal perl data structure which can then be followed
776 with the other access methods.
780 Return the PP function name (e.g. "pp_add") of op number OPNUM.
784 Returns a string in the form "0x..." representing the value of the
785 internal hash function used by perl on string STR.
789 Casts I to the internal I32 type used by that perl.
794 Does the equivalent of the C<-c> command-line option. Obviously, this
795 is only useful in a BEGIN block or else the flag is set too late.
800 Returns a double-quote-surrounded escaped version of STR which can
801 be used as a string in C source code.
805 Returns the class of an object without the part of the classname
806 preceding the first "::". This is used to turn "B::UNOP" into
811 In a perl compiled for threads, this returns a list of the special
812 per-thread threadsv variables.
814 =item byteload_fh(FILEHANDLE)
816 Load the contents of FILEHANDLE as bytecode. See documentation for
817 the B<Bytecode> module in F<B::Backend> for how to generate bytecode.
823 Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>