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
557 =head2 OP-RELATED CLASSES
559 B::OP, B::UNOP, B::BINOP, B::LOGOP, B::CONDOP, B::LISTOP, B::PMOP,
560 B::SVOP, B::GVOP, B::PVOP, B::CVOP, B::LOOP, B::COP.
561 These classes correspond in
562 the obvious way to the underlying C structures of similar names. The
563 inheritance hierarchy mimics the underlying C "inheritance". Access
564 methods correspond to the underlying C structre field names, with the
565 leading "class indication" prefix removed (op_).
577 This returns the function name as a string (e.g. pp_add, pp_rv2av).
581 This returns the op description from the global C PL_op_desc array
582 (e.g. "addition" "array deref").
596 =head2 B::UNOP METHOD
604 =head2 B::BINOP METHOD
612 =head2 B::LOGOP METHOD
620 =head2 B::CONDOP METHODS
630 =head2 B::LISTOP METHOD
638 =head2 B::PMOP METHODS
658 =head2 B::SVOP METHOD
666 =head2 B::GVOP METHOD
674 =head2 B::PVOP METHOD
682 =head2 B::LOOP METHODS
694 =head2 B::COP METHODS
712 =head1 FUNCTIONS EXPORTED BY C<B>
714 The C<B> module exports a variety of functions: some are simple
715 utility functions, others provide a Perl program with a way to
716 get an initial "handle" on an internal object.
722 Return the (faked) CV corresponding to the main part of the Perl
727 Returns the root op (i.e. an object in the appropriate B::OP-derived
728 class) of the main part of the Perl program.
732 Returns the starting op of the main part of the Perl program.
736 Returns the AV object (i.e. in class B::AV) of the global comppadlist.
740 Returns the SV object corresponding to the C variable C<sv_undef>.
744 Returns the SV object corresponding to the C variable C<sv_yes>.
748 Returns the SV object corresponding to the C variable C<sv_no>.
750 =item walkoptree(OP, METHOD)
752 Does a tree-walk of the syntax tree based at OP and calls METHOD on
753 each op it visits. Each node is visited before its children. If
754 C<walkoptree_debug> (q.v.) has been called to turn debugging on then
755 the method C<walkoptree_debug> is called on each op before METHOD is
758 =item walkoptree_debug(DEBUG)
760 Returns the current debugging flag for C<walkoptree>. If the optional
761 DEBUG argument is non-zero, it sets the debugging flag to that. See
762 the description of C<walkoptree> above for what the debugging flag
765 =item walksymtable(SYMREF, METHOD, RECURSE)
767 Walk the symbol table starting at SYMREF and call METHOD on each
768 symbol visited. When the walk reached package symbols "Foo::" it
769 invokes RECURSE and only recurses into the package if that sub
772 =item svref_2object(SV)
774 Takes any Perl variable and turns it into an object in the
775 appropriate B::OP-derived or B::SV-derived class. Apart from functions
776 such 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
778 with the other access methods.
782 Return the PP function name (e.g. "pp_add") of op number OPNUM.
786 Returns a string in the form "0x..." representing the value of the
787 internal hash function used by perl on string STR.
791 Casts I to the internal I32 type used by that perl.
796 Does the equivalent of the C<-c> command-line option. Obviously, this
797 is only useful in a BEGIN block or else the flag is set too late.
802 Returns a double-quote-surrounded escaped version of STR which can
803 be used as a string in C source code.
807 Returns the class of an object without the part of the classname
808 preceding the first "::". This is used to turn "B::UNOP" into
813 In a perl compiled for threads, this returns a list of the special
814 per-thread threadsv variables.
816 =item byteload_fh(FILEHANDLE)
818 Load the contents of FILEHANDLE as bytecode. See documentation for
819 the B<Bytecode> module in F<B::Backend> for how to generate bytecode.
825 Malcolm Beattie, C<mbeattie@sable.ox.ac.uk>