Provided by: ocaml_5.2.0-3_amd64 
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.
-no-absname
Do not try to 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)).
-no-g Do not record debugging information (default).
-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.
-cmi-file filename
Type-check the source implementation to be compiled against the specified interface
file (by-passes the normal lookup for .mli and .cmi files).
-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.
-no-principal
Do not check principality of type inference. This is the default.
-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.
-no-rectypes
Do no allow arbitrary recursive types during type-checking. This is the default.
-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.
-safe-string
Enforce the separation between types string and bytes, thereby making strings read-
only. This is the default.
-safer-matching
Do not use type information to optimize pattern-matching. This allows to detect
match failures even if a pattern-matching was wrongly assumed to be exhaustive.
This only impacts GADT and polymorphic variant compilation.
-save-ir-after pass
Save intermediate representation after the given compilation pass. The currently
supported passes are: scheduling.
-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.
-stop-after pass
Stop compilation after the given compilation pass. The currently supported passes
are: parsing, typing, scheduling, emit.
-strict-sequence
The left-hand part of a sequence must have type unit.
-no-strict-sequence
Left-hand part of a sequence need not have type unit. This is the default.
-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) 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. 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 (no warning 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 FLAMBDA MIDDLE-END
When the Flambda code generator has been enabled at configuration time, its behavior may
be tuned up with the following additional options:
-02 Perform more optimisation than usual. Compilation times may be lengthened.
-03 Perform even more optimisation than usual, possibly including unrolling of
recursive functions. Compilation times may be significantly lengthened.
-Oclassic
Makes inlining decisions at the point of definition of a function rather than at
the call site(s). This mirrors the behaviour of OCaml compilers not using Flambda.
Compared to compilation using the new Flambda inlining heuristics (for example at
-O2) it produces smaller .cmx files, shorter compilation times and code that
probably runs rather slower.
-inlining-report
Emit .inlining files (one per round of optimisation) showing all of the inliner's
decisions.
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.
SEE ALSO
ocamlc(1).
The OCaml user's manual, chapter "Native-code compilation".
OCAMLOPT(1)