B::C(3) Perl Programmers Reference Guide B::C(3)NAMEB::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
-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"
2001-02-22 perl v5.6.1 B::C(3)
