Compiler docs for 5.005

	Message-Id: <199807211713.SAA20735@sable.ox.ac.uk>

p4raw-id: //depot/perl@1617

1 files changed, 535 insertions, 2 deletions

diff --git a/ext/B/B.pm b/ext/B/B.pm
index dcf7809014..d5137d4228 100644
--- a/ext/B/B.pm
+++ b/ext/B/B.pm
@@ -1,6 +1,6 @@
 #      B.pm
 #
-#      Copyright (c) 1996, 1997 Malcolm Beattie
+#      Copyright (c) 1996, 1997, 1998 Malcolm Beattie
 #
 #      You may distribute under the terms of either the GNU General Public
 #      License or the Artistic License, as specified in the README file.
@@ -283,7 +283,540 @@ B - The Perl Compiler
 
 =head1 DESCRIPTION
 
-See F<ext/B/README>.
+The C<B> module supplies classes which allow a Perl program to delve
+into its own innards. It is the module used to implement the
+"backends" of the Perl compiler. Usage of the compiler does not
+require knowledge of this module: see the F<O> module for the
+user-visible part. The C<B> module is of use to those who want to
+write new compiler backends. This documentation assumes that the
+reader knows a fair amount about perl's internals including such
+things as SVs, OPs and the internal symbol table and syntax tree
+of a program.
+
+=head1 OVERVIEW OF CLASSES
+
+The C structures used by Perl's internals to hold SV and OP
+information (PVIV, AV, HV, ..., OP, SVOP, UNOP, ...) are modelled on a
+class hierarchy and the C<B> module gives access to them via a true
+object hierarchy. Structure fields which point to other objects
+(whether types of SV or types of OP) are represented by the C<B>
+module as Perl objects of the appropriate class. The bulk of the C<B>
+module is the methods for accessing fields of these structures. Note
+that all access is read-only: you cannot modify the internals by
+using this module.
+
+=head2 SV-RELATED CLASSES
+
+B::IV, B::NV, B::RV, B::PV, B::PVIV, B::PVNV, B::PVMG, B::BM, B::PVLV,
+B::AV, B::HV, B::CV, B::GV, B::FM, B::IO. These classes correspond in
+the obvious way to the underlying C structures of similar names. The
+inheritance hierarchy mimics the underlying C "inheritance". Access
+methods correspond to the underlying C macros for field access,
+usually with the leading "class indication" prefix removed (Sv, Av,
+Hv, ...). The leading prefix is only left in cases where its removal
+would cause a clash in method name. For example, C<GvREFCNT> stays
+as-is since its abbreviation would clash with the "superclass" method
+C<REFCNT> (corresponding to the C function C<SvREFCNT>).
+
+=head2 B::SV METHODS
+
+=over 4
+
+=item REFCNT
+
+=item FLAGS
+
+=back
+
+=head2 B::IV METHODS
+
+=over 4
+
+=item IV
+
+=item IVX
+
+=item needs64bits
+
+=item packiv
+
+=back
+
+=head2 B::NV METHODS
+
+=over 4
+
+=item NV
+
+=item NVX
+
+=back
+
+=head2 B::RV METHODS
+
+=over 4
+
+=item RV
+
+=back
+
+=head2 B::PV METHODS
+
+=over 4
+
+=item PV
+
+=back
+
+=head2 B::PVMG METHODS
+
+=over 4
+
+=item MAGIC
+
+=item SvSTASH
+
+=back
+
+=head2 B::MAGIC METHODS
+
+=over 4
+
+=item MOREMAGIC
+
+=item PRIVATE
+
+=item TYPE
+
+=item FLAGS
+
+=item OBJ
+
+=item PTR
+
+=back
+
+=head2 B::PVLV METHODS
+
+=over 4
+
+=item TARGOFF
+
+=item TARGLEN
+
+=item TYPE
+
+=item TARG
+
+=back
+
+=head2 B::BM METHODS
+
+=over 4
+
+=item USEFUL
+
+=item PREVIOUS
+
+=item RARE
+
+=item TABLE
+
+=back
+
+=head2 B::GV METHODS
+
+=over 4
+
+=item NAME
+
+=item STASH
+
+=item SV
+
+=item IO
+
+=item FORM
+
+=item AV
+
+=item HV
+
+=item EGV
+
+=item CV
+
+=item CVGEN
+
+=item LINE
+
+=item FILEGV
+
+=item GvREFCNT
+
+=item FLAGS
+
+=back
+
+=head2 B::IO METHODS
+
+=over 4
+
+=item LINES
+
+=item PAGE
+
+=item PAGE_LEN
+
+=item LINES_LEFT
+
+=item TOP_NAME
+
+=item TOP_GV
+
+=item FMT_NAME
+
+=item FMT_GV
+
+=item BOTTOM_NAME
+
+=item BOTTOM_GV
+
+=item SUBPROCESS
+
+=item IoTYPE
+
+=item IoFLAGS
+
+=back
+
+=head2 B::AV METHODS
+
+=over 4
+
+=item FILL
+
+=item MAX
+
+=item OFF
+
+=item ARRAY
+
+=item AvFLAGS
+
+=back
+
+=head2 B::CV METHODS
+
+=over 4
+
+=item STASH
+
+=item START
+
+=item ROOT
+
+=item GV
+
+=item FILEGV
+
+=item DEPTH
+
+=item PADLIST
+
+=item OUTSIDE
+
+=item XSUB
+
+=item XSUBANY
+
+=back
+
+=head2 B::HV METHODS
+
+=over 4
+
+=item FILL
+
+=item MAX
+
+=item KEYS
+
+=item RITER
+
+=item NAME
+
+=item PMROOT
+
+=item ARRAY
+
+=back
+
+=head2 OP-RELATED CLASSES
+
+B::OP, B::UNOP, B::BINOP, B::LOGOP, B::CONDOP, B::LISTOP, B::PMOP,
+B::SVOP, B::GVOP, B::PVOP, B::CVOP, B::LOOP, B::COP.
+These classes correspond in
+the obvious way to the underlying C structures of similar names. The
+inheritance hierarchy mimics the underlying C "inheritance". Access
+methods correspond to the underlying C structre field names, with the
+leading "class indication" prefix removed (op_).
+
+=head2 B::OP METHODS
+
+=over 4
+
+=item next
+
+=item sibling
+
+=item ppaddr
+
+This returns the function name as a string (e.g. pp_add, pp_rv2av).
+
+=item desc
+
+This returns the op description from the global C op_desc array
+(e.g. "addition" "array deref").
+
+=item targ
+
+=item type
+
+=item seq
+
+=item flags
+
+=item private
+
+=back
+
+=head2 B::UNOP METHOD
+
+=over 4
+
+=item first
+
+=back
+
+=head2 B::BINOP METHOD
+
+=over 4
+
+=item last
+
+=back
+
+=head2 B::LOGOP METHOD
+
+=over 4
+
+=item other
+
+=back
+
+=head2 B::CONDOP METHODS
+
+=over 4
+
+=item true
+
+=item false
+
+=back
+
+=head2 B::LISTOP METHOD
+
+=over 4
+
+=item children
+
+=back
+
+=head2 B::PMOP METHODS
+
+=over 4
+
+=item pmreplroot
+
+=item pmreplstart
+
+=item pmnext
+
+=item pmregexp
+
+=item pmflags
+
+=item pmpermflags
+
+=item precomp
+
+=back
+
+=head2 B::SVOP METHOD
+
+=over 4
+
+=item sv
+
+=back
+
+=head2 B::GVOP METHOD
+
+=over 4
+
+=item gv
+
+=back
+
+=head2 B::PVOP METHOD
+
+=over 4
+
+=item pv
+
+=back
+
+=head2 B::LOOP METHODS
+
+=over 4
+
+=item redoop
+
+=item nextop
+
+=item lastop
+
+=back
+
+=head2 B::COP METHODS
+
+=over 4
+
+=item label
+
+=item stash
+
+=item filegv
+
+=item cop_seq
+
+=item arybase
+
+=item line
+
+=back
+
+=head1 FUNCTIONS EXPORTED BY C<B>
+
+The C<B> module exports a variety of functions: some are simple
+utility functions, others provide a Perl program with a way to
+get an initial "handle" on an internal object.
+
+=over 4
+
+=item main_cv
+
+Return the (faked) CV corresponding to the main part of the Perl
+program.
+
+=item main_root
+
+Returns the root op (i.e. an object in the appropriate B::OP-derived
+class) of the main part of the Perl program.
+
+=item main_start
+
+Returns the starting op of the main part of the Perl program.
+
+=item comppadlist
+
+Returns the AV object (i.e. in class B::AV) of the global comppadlist.
+
+=item sv_undef
+
+Returns the SV object corresponding to the C variable C<sv_undef>.
+
+=item sv_yes
+
+Returns the SV object corresponding to the C variable C<sv_yes>.
+
+=item sv_no
+
+Returns the SV object corresponding to the C variable C<sv_no>.
+
+=item walkoptree(OP, METHOD)
+
+Does a tree-walk of the syntax tree based at OP and calls METHOD on
+each op it visits. Each node is visited before its children. If
+C<walkoptree_debug> (q.v.) has been called to turn debugging on then
+the method C<walkoptree_debug> is called on each op before METHOD is
+called.
+
+=item walkoptree_debug(DEBUG)
+
+Returns the current debugging flag for C<walkoptree>. If the optional
+DEBUG argument is non-zero, it sets the debugging flag to that. See
+the description of C<walkoptree> above for what the debugging flag
+does.
+
+=item walksymtable(SYMREF, METHOD, RECURSE)
+
+Walk the symbol table starting at SYMREF and call METHOD on each
+symbol visited. When the walk reached package symbols "Foo::" it
+invokes RECURSE and only recurses into the package if that sub
+returns true.
+
+=item svref_2object(SV)
+
+Takes any Perl variable and turns it into an object in the
+appropriate B::OP-derived or B::SV-derived class. Apart from functions
+such as C<main_root>, this is the primary way to get an initial
+"handle" on a internal perl data structure which can then be followed
+with the other access methods.
+
+=item ppname(OPNUM)
+
+Return the PP function name (e.g. "pp_add") of op number OPNUM.
+
+=item hash(STR)
+
+Returns a string in the form "0x..." representing the value of the
+internal hash function used by perl on string STR.
+
+=item cast_I32(I)
+
+Casts I to the internal I32 type used by that perl.
+
+
+=item minus_c
+
+Does the equivalent of the C<-c> command-line option. Obviously, this
+is only useful in a BEGIN block or else the flag is set too late.
+
+
+=item cstring(STR)
+
+Returns a double-quote-surrounded escaped version of STR which can
+be used as a string in C source code.
+
+=item class(OBJ)
+
+Returns the class of an object without the part of the classname
+preceding the first "::". This is used to turn "B::UNOP" into
+"UNOP" for example.
+
+=item threadsv_names
+
+In a perl compiled for threads, this returns a list of the special
+per-thread threadsv variables.
+
+=item byteload_fh(FILEHANDLE)
+
+Load the contents of FILEHANDLE as bytecode. See documentation for
+the B<Bytecode> module in F<B::Backend> for how to generate bytecode.
+
+=back
 
 =head1 AUTHOR