B::C(3pm) Perl Programmers Reference Guide B::C(3pm)
NAME
B::C - Perl compiler's C backend
SYNOPSIS
perl -MO=C[,OPTIONS] foo.pl
DESCRIPTION
This compiler backend takes Perl source and generates C source code corresponding to the internal
structures that perl uses to run your program. When the generated C source is compiled and run, it
cuts out the time which perl would have taken to load and parse your program into its internal semi-compiled semicompiled
compiled form. That means that compiling with this backend will not help improve the runtime execu-tion execution
tion speed of your program but may improve the start-up time. Depending on the environment in which
your program runs this may be either a help or a hindrance.
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
-v Verbose compilation (currently gives a few compilation statistics).
-- Force end of options
-uPackname
Force apparently unused subs from package Packname to be compiled. This allows programs to use
eval "foo()" even when sub foo is never seen to be used at compile time. The down side is that
any subs which really are never used also have code generated. This option is necessary, for
example, if you have a signal handler foo which you initialise with "$SIG{BAR} = "foo"". A bet-ter better
ter fix, though, is just to change it to "$SIG{BAR} = \&foo". You can have multiple -u options.
The compiler tries to figure out which packages may possibly have subs in which need compiling
but the current version doesn't do it very well. In particular, it is confused by nested packages
(i.e. of the form "A::B") where package "A" does not contain any subs.
-D Debug options (concatenated or separate flags like "perl -D").
-Do OPs, prints each OP as it's processed
-Dc COPs, prints COPs as processed (incl. file & line num)
-DA prints AV information on saving
-DC prints CV information on saving
-DM prints MAGIC information on saving
-f Force options/optimisations on or off one at a time. You can explicitly disable an option using
-fno-option. All options default to disabled.
-fcog
Copy-on-grow: PVs declared and initialised statically.
-fsave-data
Save package::DATA filehandles ( only available with PerlIO ).
-fppaddr
Optimize the initialization of op_ppaddr.
-fwarn-sv
Optimize the initialization of cop_warnings.
-fuse-script-name
Use the script name instead of the program name as $0.
-fsave-sig-hash
Save compile-time modifications to the %SIG hash.
-On Optimisation level (n = 0, 1, 2, ...). -O means -O1.
-O0 Disable all optimizations.
-O1 Enable -fcog.
-O2 Enable -fppaddr, -fwarn-sv.
-llimit
Some C compilers impose an arbitrary limit on the length of string constants (e.g. 2048 charac-ters characters
ters for Microsoft Visual C++). The -llimit options tells the C backend not to generate string
literals exceeding that limit.
EXAMPLES
perl -MO=C,-ofoo.c foo.pl
perl cc_harness -o foo foo.c
Note that "cc_harness" lives in the "B" subdirectory of your perl library directory. The utility
called "perlcc" may also be used to help make use of this compiler.
perl -MO=C,-v,-DcA,-l2048 bar.pl > /dev/null
BUGS
Plenty. Current status: experimental.
AUTHOR
Malcolm Beattie, "mbeattie@sable.ox.ac.uk"
perl v5.8.8 2001-09-21 B::C(3pm)
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