B::C

B::C(3)		       Perl Programmers Reference Guide		      B::C(3)



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 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 environ-
       ment in which your program runs this may be either a help or a hin-
       drance.

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 statis-
	   tics).

       --  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 "$SIG{BAR} = "foo"".  A better fix,
	   though, is just to change it to "$SIG{BAR} = \&foo". You can have
	   multiple -u options. The compiler tries to figure out which pack-
	   ages may possibly have subs in which need compiling but the cur-
	   rent version doesn’t do it very well. In particular, it is con-
	   fused 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 characters for Microsoft Visual C++).  The
	   -llimit options tells the C backend not to generate string liter-
	   als 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(3)