OCAMLOPT(1) User Commands OCAMLOPT(1)

NAME

ocamlopt - The OCaml native-code compiler

SYNOPSIS

ocamlopt [ options ] filename ...

ocamlopt.opt (same options)

DESCRIPTION

The OCaml high-performance native-code compiler ocamlopt(1) compiles
OCaml source files to native code object files and link these object
files to produce standalone executables.

The ocamlopt(1) command has a command-line interface very close to
that of ocamlc(1). It accepts the same types of arguments and
processes them sequentially, after all options have been processed:

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 x.mli,
the ocamlopt(1) compiler produces a compiled interface in the file
x.cmi. The interface produced is identical to that produced by the
bytecode compiler 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 x.ml, the
ocamlopt(1) compiler produces two files: x.o, containing native
object code, and 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 x.cmx (when given a .o
file, ocamlopt(1) assumes that it contains code compiled from C, not
from OCaml).

The implementation is checked against the interface file x.mli (if it
exists) as described in the manual for 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 OCaml 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 x.cmx file must come before all .cmx
files that refer to the unit x.

Arguments ending in .cmxa are taken to be libraries of object code.
Such a library packs in two files lib.cmxa and lib.a a set of object
files (.cmx/.o files). Libraries are build with ocamlopt -a (see the
description of the -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 ocamlrun(1) to run.

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

OPTIONS

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

-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 must be set with
the -o option.

If -cclib or -ccopt options are passed on the command line,
these options are stored in the resulting .cmxa library.
Then, linking with this library automatically adds back the
-cclib and -ccopt options as if they had been provided on the
command line, unless the -noautolink option is given.
Additionally, a substring $CAMLORIGIN inside a -ccopt options
will be replaced by the full path to the .cma library,
excluding the filename.

-absname
Show absolute filenames in error messages.

-annot Deprecated since OCaml 4.11. Please use -bin-annot instead.

-bin-annot
Dump detailed information about the compilation (types,
bindings, tail-calls, etc) in binary format. The information
for file src.ml is put into file src.cmt. In case of a type
error, dump all the information inferred by the type-checker
before the error. The annotation files produced by -bin-annot
contain more information and are much more compact than the
files produced by -annot.

-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.

-cc ccomp
Use ccomp as the C linker called to build the final executable
and as the C compiler for compiling .c source files.

-cclib -llibname
Pass the -llibname option to the linker. This causes the given
C library to be linked with the program.

-ccopt option
Pass the given option to the C compiler and linker. For
instance, -ccopt -Ldir causes the C linker to search for C
libraries in directory dir.

-color mode
Enable or disable colors in compiler messages (especially
warnings and errors). The following modes are supported:

auto use heuristics to enable colors only if the output
supports them (an ANSI-compatible tty terminal);

always enable colors unconditionally;

never disable color output.

The environment variable "OCAML_COLOR" is considered if -color
is not provided. Its values are auto/always/never as above.

If -color is not provided, "OCAML_COLOR" is not set and the
environment variable "NO_COLOR" is set, then color output is
disabled. Otherwise, the default setting is auto, and the
current heuristic checks that the "TERM" environment variable
exists and is not empty or "dumb", and that isatty(stderr)
holds.


-error-style mode
Control the way error messages and warnings are printed. The
following modes are supported:

short only print the error and its location;

contextual like "short", but also display the source code
snippet corresponding to the location of the error.

The default setting is contextual.

The environment variable "OCAML_ERROR_STYLE" is considered if
-error-style is not provided. Its values are short/contextual
as above.


-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.

-config
Print the version number of ocamlopt(1) and a detailed summary
of its configuration, then exit.

-config-var
Print the value of a specific configuration variable from the
-config output, then exit. If the variable does not exist, the
exit code is non-zero.

-depend ocamldep-args
Compute dependencies, as ocamldep would do.

-for-pack module-path
Generate an object file (.cmx and .o files) that can later be
included as a sub-module (with the given access path) of a
compilation unit constructed with -pack. For instance,
ocamlopt -for-pack P -c A.ml will generate a.cmx and a.o files
that can later be used with ocamlopt -pack -o P.cmx a.cmx.

-g Add debugging information while compiling and linking. This
option is required in order to produce stack backtraces when
the program terminates on an uncaught exception (see
ocamlrun(1)).

-i Cause the compiler to print all defined names (with their
inferred types or their definitions) when compiling an
implementation (.ml file). No compiled files (.cmo and .cmi
files) are produced. 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.

-I directory
Add the given directory to the list of directories searched
for compiled interface files (.cmi), compiled object code
files (.cmx), and libraries (.cmxa). 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.
See also option -nostdlib.

If the given directory starts with +, it is taken relative to
the standard library directory. For instance,
-I +compiler-libs adds the subdirectory compiler-libs of the
standard library to the search path.

-impl filename
Compile the file filename as an implementation file, even if
its extension is not .ml.

-inline n
Set aggressiveness of inlining to n, where n is a positive
integer. Specifying -inline 0 prevents all functions from
being inlined, except those whose body is smaller than the
call site. Thus, inlining causes no expansion in code size.
The default aggressiveness, -inline 1, allows slightly larger
functions to be inlined, resulting in a slight expansion in
code size. Higher values for the -inline option cause larger
and larger functions to become candidate for inlining, but can
result in a serious increase in code size.

-insn-sched
Enables the instruction scheduling pass in the compiler
backend.

-intf filename
Compile the file filename as an interface file, even if its
extension is not .mli.

-intf-suffix string
Recognize file names ending with string as interface files
(instead of the default .mli).

-keep-docs
Keep documentation strings in generated .cmi files.

-keep-locs
Keep locations in generated .cmi files.

-labels
Labels are not ignored in types, labels may be used in
applications, and labelled parameters can be given in any
order. This is the default.

-linkall
Force all modules contained in libraries to be linked in. If
this flag is not given, unreferenced modules are not linked
in. When building a library (-a flag), setting the -linkall
flag forces all subsequent links of programs involving that
library to link all the modules contained in the library.
When compiling a module (option -c), setting the -linkall
option ensures that this module will always be linked if it is
put in a library and this library is linked.

-linscan
Use linear scan register allocation. Compiling with this
allocator is faster than with the usual graph coloring
allocator, sometimes quite drastically so for long functions
and modules. On the other hand, the generated code can be a
bit slower.

-match-context-rows
Set number of rows of context used during pattern matching
compilation. Lower values cause faster compilation, but less
optimized code. The default value is 32.

-no-alias-deps
Do not record dependencies for module aliases.

-no-app-funct
Deactivates the applicative behaviour of functors. With this
option, each functor application generates new types in its
result and applying the same functor twice to the same
argument yields two incompatible structures.

-noassert
Do not compile assertion checks. Note that the special form
assert false is always compiled because it is typed specially.
This flag has no effect when linking already-compiled files.

-noautolink
When linking .cmxa libraries, ignore -cclib and -ccopt options
potentially contained in the libraries (if these options were
given when building the libraries). This can be useful if a
library contains incorrect specifications of C libraries or C
options; in this case, during linking, set -noautolink and
pass the correct C libraries and options on the command line.

-nodynlink
Allow the compiler to use some optimizations that are valid
only for code that is never dynlinked.

-no-insn-sched
Disables the instruction scheduling pass in the compiler
backend.

-nostdlib
Do not automatically add the standard library directory to the
list of directories searched for compiled interface files
(.cmi), compiled object code files (.cmx), and libraries
(.cmxa). See also option -I.

-nolabels
Ignore non-optional labels in types. Labels cannot be used in
applications, and parameter order becomes strict.

-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 -a option is given, specify the name of the
library produced. If the -pack option is given, specify the
name of the packed object file produced. If the -output-obj
option is given, specify the name of the output file produced.
If the -shared option is given, specify the name of plugin
file produced. This can also be used when compiling an
interface or implementation file, without linking, in which
case it sets the name of the cmi or cmo file, and also sets
the module name to the file name up to the first dot.

-opaque
When compiling a .mli interface file, this has the same effect
as the -opaque option of the bytecode compiler. When compiling
a .ml implementation file, this produces a .cmx file without
cross-module optimization information, which reduces
recompilation on module change.

-open module
Opens the given module before processing the interface or
implementation files. If several -open options are given, they
are processed in order, just as if the statements open!
module1;; ... open! moduleN;; were added at the top of each
file.

-output-obj
Cause the linker to produce a C object file instead of an
executable file. This is useful to wrap OCaml code as a C
library, callable from any C program. The name of the output
object file must be set with the -o option. This option can
also be used to produce a compiled shared/dynamic library (.so
extension). -output-complete-obj Same as -output-obj except
the object file produced includes the runtime and autolink
libraries.

-pack Build an object file (.cmx and .o files) and its associated
compiled interface (.cmi) that combines the .cmx object files
given on the command line, making them appear as sub-modules
of the output .cmx file. The name of the output .cmx file
must be given with the -o option. For instance,
ocamlopt -pack -o P.cmx A.cmx B.cmx C.cmx generates compiled
files P.cmx, P.o and P.cmi describing a compilation unit
having three sub-modules A, B and C, corresponding to the
contents of the object files A.cmx, B.cmx and C.cmx. These
contents can be referenced as P.A, P.B and P.C in the
remainder of the program.

The .cmx object files being combined must have been compiled
with the appropriate -for-pack option. In the example above,
A.cmx, B.cmx and C.cmx must have been compiled with
ocamlopt -for-pack P.

Multiple levels of packing can be achieved by combining -pack
with -for-pack. See The OCaml user's manual, chapter "Native-
code compilation" for more details.

-pp command
Cause the compiler to call the given command as a preprocessor
for each source file. The output of command is redirected to
an intermediate file, which is compiled. If there are no
compilation errors, the intermediate file is deleted
afterwards.

-ppx command
After parsing, pipe the abstract syntax tree through the
preprocessor command. The module Ast_mapper(3) implements the
external interface of a preprocessor.

-principal
Check information path during type-checking, to make sure that
all types are derived in a principal way. All programs
accepted in -principal mode are also accepted in default mode
with equivalent types, but different binary signatures.

-rectypes
Allow arbitrary recursive types during type-checking. By
default, only recursive types where the recursion goes through
an object type are supported. Note that once you have created
an interface using this flag, you must use it again for all
dependencies.

-runtime-variant suffix
Add suffix to the name of the runtime library that will be
used by the program. If OCaml was configured with option
-with-debug-runtime, then the d suffix is supported and gives
a debug version of the runtime.

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

-stop-after pass
Stop compilation after the given compilation pass. The
currently supported passes are: parsing, typing, scheduling,
emit.

-save-ir-after pass
Save intermediate representation after the given compilation
pass. The currently supported passes are: scheduling.

-safe-string
Enforce the separation between types string and bytes, thereby
making strings read-only. This is the default.

-shared
Build a plugin (usually .cmxs) that can be dynamically loaded
with the Dynlink module. The name of the plugin must be set
with the -o option. A plugin can include a number of OCaml
modules and libraries, and extra native objects (.o, .a
files). Building native plugins is only supported for some
operating system. Under some systems (currently, only Linux
AMD 64), all the OCaml code linked in a plugin must have been
compiled without the -nodynlink flag. Some constraints might
also apply to the way the extra native objects have been
compiled (under Linux AMD 64, they must contain only position-
independent code).

-short-paths
When a type is visible under several module-paths, use the
shortest one when printing the type's name in inferred
interfaces and error and warning messages.

-strict-sequence
The left-hand part of a sequence must have type unit.

-unboxed-types
When a type is unboxable (i.e. a record with a single argument
or a concrete datatype with a single constructor of one
argument) it will be unboxed unless annotated with
[@@ocaml.boxed].

-no-unboxed-types
When a type is unboxable it will be boxed unless annotated
with [@@ocaml.unboxed]. This is the default.

-unsafe
Turn bound checking off for array and string accesses (the
v.(i)ands.[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.
Additionally, turn off the check for zero divisor in integer
division and modulus operations. With -unsafe, an integer
division (or modulus) by zero can halt the program or continue
with an unspecified result instead of raising a
Division_by_zero exception.

-unsafe-string
Identify the types string and bytes, thereby making strings
writable. This is intended for compatibility with old source
code and should not be used with new software.

-v Print the version number of the compiler and the location of
the standard library directory, then exit.

-verbose
Print all external commands before they are executed, in
particular invocations of the assembler, C compiler, and
linker.

-version or -vnum
Print the version number of the compiler in short form (e.g.
"3.11.0"), then exit.

-w warning-list
Enable, disable, or mark as fatal the warnings specified by
the argument warning-list. See ocamlc(1) for the syntax of
warning-list.

-warn-error warning-list
Mark as fatal the warnings specified in the argument
warning-list. The compiler will stop with an error when one
of these warnings is emitted. The warning-list has the same
meaning as for the -w option: a + sign (or an uppercase
letter) marks the corresponding warnings as fatal, a - sign
(or a lowercase letter) turns them back into non-fatal
warnings, and a @ sign both enables and marks as fatal the
corresponding warnings.

Note: it is not recommended to use the -warn-error option in
production code, because it will almost certainly prevent
compiling your program with later versions of OCaml when they
add new warnings or modify existing warnings.

The default setting is -warn-error -a+31 (only warning 31 is
fatal).

-warn-help
Show the description of all available warning numbers.

-where Print the location of the standard library, then exit.

-with-runtime
Include the runtime system in the generated program. This is
the default.

-without-runtime
The compiler does not include the runtime system (nor a
reference to it) in the generated program; it must be supplied
separately.

- file Process file as a file name, even if it starts with a dash (-)
character.

-help or --help
Display a short usage summary and exit.


OPTIONS FOR THE IA32 ARCHITECTURE
The IA32 code generator (Intel Pentium, AMD Athlon) supports the
following additional option:

-ffast-math
Use the IA32 instructions to compute trigonometric and
exponential functions, instead of calling the corresponding
library routines. The functions affected are: atan, atan2,
cos, log, log10, sin, sqrt and tan. The resulting code runs
faster, but the range of supported arguments and the precision
of the result can be reduced. In particular, trigonometric
operations cos, sin, tan have their range reduced to [-2^64,
2^64].


OPTIONS FOR THE AMD64 ARCHITECTURE
The AMD64 code generator (64-bit versions of Intel Pentium and AMD
Athlon) supports the following additional options:

-fPIC Generate position-independent machine code. This is the
default.

-fno-PIC
Generate position-dependent machine code.

OPTIONS FOR THE POWER ARCHITECTURE

The PowerPC code generator supports the following additional options:

-flarge-toc
Enables the PowerPC large model allowing the TOC (table of
contents) to be arbitrarily large. This is the default since
4.11.

-fsmall-toc
Enables the PowerPC small model allowing the TOC to be up to
64 kbytes per compilation unit. Prior to 4.11 this was the
default behaviour. \nd{options}

OPTIONS FOR THE ARM ARCHITECTURE

The ARM code generator supports the following additional options:

-farch=armv4|armv5|armv5te|armv6|armv6t2|armv7
Select the ARM target architecture

-ffpu=soft|vfpv2|vfpv3-d16|vfpv3
Select the floating-point hardware

-fPIC Generate position-independent machine code.

-fno-PIC
Generate position-dependent machine code. This is the
default.

-fthumb
Enable Thumb/Thumb-2 code generation

-fno-thumb
Disable Thumb/Thumb-2 code generation

The default values for target architecture, floating-point hardware
and thumb usage were selected at configure-time when building
ocamlopt itself. This configuration can be inspected using
ocamlopt -config. Target architecture depends on the "model"
setting, while floating-point hardware and thumb support are
determined from the ABI setting in "system" (
linux_eabiorlinux_eabihf).

SEE ALSO

ocamlc(1).
The OCaml user's manual, chapter "Native-code compilation".

OCAMLOPT(1)