The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.


B::Bytecode - Perl compiler's bytecode backend


perl -MO=Bytecode[,-H][,-oscript.plc]


Compiles a Perl script into a bytecode format that could be loaded later by the ByteLoader module and executed as a regular Perl script. This saves time for the optree parsing and compilation and space for the sourcecode in memory.


    $ perl -MO=Bytecode,-H,-ohi -e 'print "hi!\n"'
    $ perl hi



Prepend a use ByteLoader VERSION; line to the produced bytecode. This way you will not need to add -MByteLoader to your perl command-line.

Beware: This option does not yet work with 5.18 and higher. You need to use -MByteLoader still.

-i includeall

Include all used packages and its symbols. Does no run-time require from BEGIN blocks (use package).

This creates bigger and more independent code, but is more error prone and does not support pre-compiled .pmc modules.

It is highly recommended to use -i together with -b safebegin.

-b savebegin

Save all the BEGIN blocks.

Normally only BEGIN blocks that require other files (ex. use Foo;) or push|unshift to @INC are saved.


Keep the syntax tree - it is stripped by default.


Put the bytecode in <outfile> instead of dumping it to STDOUT.


Scan the script for # line .. directives and for <goto LABEL> expressions. When gotos are found keep the syntax tree.


Output assembler source rather than piping it through the assembler and outputting bytecode. Without -q the assembler source is commented.


Compile to a .pmc module rather than to a single standalone .plc program.

Currently this just means that the bytecodes for initialising main_start, main_root, main_cv and curpad are omitted.


"use package." Might be needed of the package is not automatically detected.


Include file. If not -i define all symbols in the given included source file. -i would all included files, -F only a certain file - full path needed.


Be quiet.


Be verbose.


Restore full @INC for running within the CORE testsuite.

-TF cop file

Set the COP file - for running within the CORE testsuite.


OPs, prints each OP as it's processed


Debugging flag for more verbose STDERR output.

M for Magic and Matches.


Debug GV's


Set developer Assertions, to help find possible obj-indices out of range.


  • 5.10 threaded fails with setting the wrong MATCH op_pmflags 5.10 non-threaded fails calling anoncode, ...

  • BEGIN { goto A: while 1; A: } won't even compile.

  • ?...? and reset do not work as expected.

  • variables in (?{ ... }) constructs are not properly scoped.

  • Scripts that use source filters will fail miserably.

  • Special GV's fail.


There are also undocumented bugs and options.


Originally written by Malcolm Beattie 1996 and modified by Benjamin Stuhl <>.

Rewritten by Enache Adrian <>, 2003 a.d.

Enhanced by Reini Urban <>, 2008-2012