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8.12. 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[,options] program

in which 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.

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

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

b
Prints debugging information about bytecompiler progress

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

o
Prints each OP as it's processed

-fopt
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:

bypass-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.

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

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

strip-syntax-tree
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.

-m
Compiles as a module rather than as a standalone program.

-ofilename
Sends output to filename instead of STDOUT.

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

-S
Outputs bytecode assembler source instead of assembling it into bytecode.



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