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8.10 B::Bytecode

The bytecode backend for the Perl compiler. Takes Perl source code and generates platform-independent bytecode that can be run with the byteperl executable or can be loaded via the byteload_fh function in the B module. Compiling with the Bytecode backend won't speed up execution of your program, but it may improve start-up time. Invoke as:

perl -MO=Bytecode[,
where program is the name of the Perl script to compile. Any non-option arguments are treated as the names of objects to be saved; the main program is assumed if there are no extra arguments. Possible options are:


Forces end of options.


Debug options, which can be either concatenated or specified separately. Possible options are:


Tells the bytecode assembler to include assembler source in its output as bytecode comments.


Prints debugging information about bytecompiler progress.


Prints each CV from the final walk through the symbol tree.


Prints each OP as it's processed.


Forces individual optimizations on or off. Preceding an optimization with no- turns that option off (e.g., no-compress-nullops ). Possible values of opt are:


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


Fills in only the necessary fields of ops that have been optimized away by Perl's internal compiler.


Leaves out the code to fill in the op_seq field for all ops that are used only by Perl's internal compiler.


Leaves out the code to fill in the internal syntax tree pointers. Use of this option breaks any goto label statements and prevents later recompiling or disassembling of the resulting program.


Compiles as a module rather than as a standalone program.


Sends output to filename instead of STDOUT.

-O[ n ]

Sets the optimization level to n , where n is an integer. n defaults to 1. -O1 sets -fcompress-nullops -fomit-sequence-numbers , and -O6 adds -fstrip-syntax-tree .


Outputs bytecode assembler source instead of assembling it into bytecode.