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 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 compiler tries to figure out which packages may possi-
           bly 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 con-
           tain 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 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 v5.8.6                       2001-09-21                           B::C(3)