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