path: root/man/ocamlopt.m

.TH OCAMLOPT 1

.SH NAME
ocamlopt \- The Objective Caml native-code compiler


.SH SYNOPSIS
.B ocamlopt
[
.B \-acivS
]
[
.BI \-cclib \ libname
]
[
.BI \-ccopt \ option
]
[
.B \-compact
]
[
.B \-labels
]
[
.B \-unsafe
]
[
.BI \-o \ exec-file
]
[
.BI \-I \ lib-dir
]
.I filename ...

.B ocamlopt.opt
.I (same options)

.SH DESCRIPTION
The Objective Caml high-performance
native-code compiler 
.BR ocamlopt (1)
compiles Caml source files to native code object files and link these
object files to produce standalone executables.

The 
.BR ocamlopt (1)
command has a command-line interface very close to that
of 
.BR ocamlc (1).
It accepts the same types of arguments:

Arguments ending in .mli are taken to be source files for
compilation unit interfaces. Interfaces specify the names exported by
compilation units: they declare value names with their types, define
public data types, declare abstract data types, and so on. From the
file 
.IR x \&.mli,
the 
.BR ocamlopt (1)
compiler produces a compiled interface
in the file 
.IR x \&.cmi.
The interface produced is identical to that
produced by the bytecode compiler 
.BR ocamlc (1).

Arguments ending in .ml are taken to be source files for compilation
unit implementations. Implementations provide definitions for the
names exported by the unit, and also contain expressions to be
evaluated for their side-effects.  From the file 
.IR x \&.ml,
the 
.BR ocamlc (1)
compiler produces two files: 
.IR x \&.o,
containing native object code, and 
.IR x \&.cmx,
containing extra information for linking and
optimization of the clients of the unit. The compiled implementation
should always be referred to under the name 
.IR x \&.cmx
(when given a .o file, 
.BR ocamlopt (1)
assumes that it contains code compiled from C, not from Caml).

The implementation is checked against the interface file 
.IR x \&.mli
(if it exists) as described in the manual for 
.BR ocamlc (1).

Arguments ending in .cmx are taken to be compiled object code.  These
files are linked together, along with the object files obtained
by compiling .ml arguments (if any), and the Caml Light standard
library, to produce a native-code executable program. The order in
which .cmx and .ml arguments are presented on the command line is
relevant: compilation units are initialized in that order at
run-time, and it is a link-time error to use a component of a unit
before having initialized it. Hence, a given 
.IR x \&.cmx
file must come
before all .cmx files that refer to the unit 
.IR x .

Arguments ending in .cmxa are taken to be libraries of object code.
Such a library packs in two files
.IR lib \&.cmxa
and 
.IR lib \&.a
a set of object files (.cmx/.o files). Libraries are build with
.B ocamlopt \-a
(see the description of the
.B \-a
option below). The object
files contained in the library are linked as regular .cmx files (see
above), in the order specified when the library was built. The only
difference is that if an object file contained in a library is not
referenced anywhere in the program, then it is not linked in.

Arguments ending in .c are passed to the C compiler, which generates
a .o object file. This object file is linked with the program.

Arguments ending in .o or .a are assumed to be C object files and
libraries. They are linked with the program.

The output of the linking phase is a regular Unix executable file. It
does not need 
.BR ocamlrun (1)
to run.

.B ocamlopt.opt
is the same compiler as
.BR ocamlopt ,
but compiled with itself instead of with the bytecode compiler
.BR ocamlc (1).
Thus, it behaves exactly like
.BR ocamlopt ,
but compiles faster.
.B ocamlopt.opt
is not available in all installations of Objective Caml.

.SH OPTIONS

The following command-line options are recognized by 
.BR ocamlopt (1).

.TP
.B \-a
Build a library (.cmxa/.a file) with the object files (.cmx/.o
files) given on the command line, instead of linking them into an
executable file. The name of the library can be set with the 
.B \-o
option. The default name is library.cmxa.

.TP
.B \-c
Compile only. Suppress the linking phase of the
compilation. Source code files are turned into compiled files, but no
executable file is produced. This option is useful to
compile modules separately.

.TP
.BI \-cclib\ -l libname
Pass the
.BI -l libname
option to the linker. This causes the given C library to be linked
with the program.

.TP
.BI \-ccopt \ option
Pass the given option to the C compiler and linker. For instance,
.B -ccopt -L
.I dir
causes the C linker to search for C libraries in
directory 
.IR dir .

.TP
.B \-compact
Optimize the produced code for space rather than for time. This
results in smaller but slightly slower programs. The default is to
optimize for speed.

.TP
.B \-i
Cause the compiler to print all defined names (with their inferred
types or their definitions) when compiling an implementation (.ml
file). This can be useful to check the types inferred by the
compiler. Also, since the output follows the syntax of interfaces, it
can help in writing an explicit interface (.mli file) for a file:
just redirect the standard output of the compiler to a .mli file,
and edit that file to remove all declarations of unexported names.

.TP
.BI \-I \ directory
Add the given directory to the list of directories searched for
compiled interface files (.cmi) and compiled object code files
(.cmo). By default, the current directory is searched first, then the
standard library directory. Directories added with -I are searched
after the current directory, in the order in which they were given on
the command line, but before the standard library directory.

.TP
.BI \-o \ exec-file
Specify the name of the output file produced by the linker. The
default output name is a.out, in keeping with the Unix tradition. If
the 
.B \-a
option is given, specify the name of the library produced.

.TP
.B \-S
Keep the assembly code produced during the compilation. The assembly
code for the source file 
.IR x \&.ml
is saved in the file 
.IR x \&.s.

.TP
.B \-v
Print the version number of the compiler.

.TP
.B \-labels
Switch to ``commuting label mode''. Arguments must be
explicitly labeled by labels appearing in types. Arguments with different
labels may commute freely.

.TP
.B \-unsafe
Turn bound checking off on array and string accesses (the v.(i) and
s.[i] constructs). Programs compiled with -unsafe are therefore
faster, but unsafe: anything can happen if the program accesses an
array or string outside of its bounds.

.SH SEE ALSO
.BR ocamlc (1).
.br
.I The Objective Caml user's manual,
chapter "Native-code compilation".