B::Bytecode

B::Bytecode(3)         Perl Programmers Reference Guide         B::Bytecode(3)



NAME
       B::Bytecode - Perl compiler's bytecode backend

SYNOPSIS
               perl -MO=Bytecode[,OPTIONS] foo.pl


DESCRIPTION
       This compiler backend takes Perl source and generates a platform-
       independent bytecode encapsulating code to load the internal structures
       perl uses to run your program. When the generated bytecode is loaded
       in, your program is ready to run, reducing the time which perl would
       have taken to load and parse your program into its internal semi-
       compiled form. That means that compiling with this backend will not
       help improve the runtime execution speed of your program but may
       improve the start-up time.  Depending on the environment in which your
       program runs this may or may not be a help.

       The resulting bytecode can be run with a special byteperl executable or
       (for non-main programs) be loaded via the byteload_fh function in the B
       module.

OPTIONS
       If there are any non-option arguments, they are taken to be names of
       objects to be saved (probably doesn't work properly yet).  Without
       extra arguments, it saves the main program.

       -ofilename
           Output to filename instead of STDOUT.

       --  Force end of options.

       -f  Force optimisations on or off one at a time. Each can be preceded
           by no- to turn the option off (e.g. -fno-compress-nullops).

       -fcompress-nullops
           Only fills in the necessary fields of ops which have been optimised
           away by perl's internal compiler.

       -fomit-sequence-numbers
           Leaves out code to fill in the op_seq field of all ops which is
           only used by perl's internal compiler.

       -fbypass-nullops
           If op->op_next ever points to a NULLOP, replaces the op_next field
           with the first non-NULLOP in the path of execution.

       -fstrip-syntax-tree
           Leaves out code to fill in the pointers which link the internal
           syntax tree together. They're not needed at run-time but leaving
           them out will make it impossible to recompile or disassemble the
           resulting program.  It will also stop goto label statements from
           working.

       -On Optimisation level (n = 0, 1, 2, ...). -O means -O1.  -O1 sets
           -fcompress-nullops -fomit-sequence numbers.  -O6 adds -fstrip-
           syntax-tree.

       -D  Debug options (concatenated or separate flags like perl -D).

       -Do Prints each OP as it's processed.

       -Db Print debugging information about bytecompiler progress.

       -Da Tells the (bytecode) assembler to include source assembler lines in
           its output as bytecode comments.

       -DC Prints each CV taken from the final symbol tree walk.

       -S  Output (bytecode) assembler source rather than piping it through
           the assembler and outputting bytecode.

       -m  Compile as a module rather than a standalone program. Currently
           this just means that the bytecodes for initialising main_start,
           main_root and curpad are omitted.

EXAMPLES
               perl -MO=Bytecode,-O6,-o,foo.plc foo.pl

               perl -MO=Bytecode,-S foo.pl > foo.S
               assemble foo.S > foo.plc
               byteperl foo.plc

               perl -MO=Bytecode,-m,-oFoo.pmc Foo.pm


BUGS
       Plenty. Current status: experimental.

AUTHOR
       Malcolm Beattie, mbeattie@sable.ox.ac.uk



























3rd Berkeley Distribution    perl 5.005, patch 02               B::Bytecode(3)