


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


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 inter-
       nal 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 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 "$SIG{BAR} = "foo"".  A
           better fix, though, is just to change it to "$SIG{BAR}
           = \&foo". You can have multiple -u options. The com-
           piler tries to figure out which packages may possibly
           have subs in which need compiling but the current ver-
           sion 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




2001-05-24                 perl v5.6.1                          1





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


       -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 optimisations on or off one at a time.

       -fcog
           Copy-on-grow: PVs declared and initialised statically.

       -fno-cog
           No copy-on-grow.

       -On Optimisation level (n = 0, 1, 2, ...). -O means -O1.
           Currently, -O1 and higher set -fcog.

       -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 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"















2001-05-24                 perl v5.6.1                          2


