1opt - LLVM optimizer
2====================
3
4.. program:: opt
5
6SYNOPSIS
7--------
8
9:program:`opt` [*options*] [*filename*]
10
11DESCRIPTION
12-----------
13
14The :program:`opt` command is the modular LLVM optimizer and analyzer.  It
15takes LLVM source files as input, runs the specified optimizations or analyses
16on it, and then outputs the optimized file or the analysis results.  The
17function of :program:`opt` depends on whether the `-analyze` option is
18given.
19
20When `-analyze` is specified, :program:`opt` performs various analyses
21of the input source.  It will usually print the results on standard output, but
22in a few cases, it will print output to standard error or generate a file with
23the analysis output, which is usually done when the output is meant for another
24program.
25
26While `-analyze` is *not* given, :program:`opt` attempts to produce an
27optimized output file.  The optimizations available via :program:`opt` depend
28upon what libraries were linked into it as well as any additional libraries
29that have been loaded with the :option:`-load` option.  Use the :option:`-help`
30option to determine what optimizations you can use.
31
32If ``filename`` is omitted from the command line or is "``-``", :program:`opt`
33reads its input from standard input.  Inputs can be in either the LLVM assembly
34language format (``.ll``) or the LLVM bitcode format (``.bc``).
35
36If an output filename is not specified with the :option:`-o` option,
37:program:`opt` writes its output to the standard output.
38
39OPTIONS
40-------
41
42.. option:: -f
43
44 Enable binary output on terminals.  Normally, :program:`opt` will refuse to
45 write raw bitcode output if the output stream is a terminal.  With this option,
46 :program:`opt` will write raw bitcode regardless of the output device.
47
48.. option:: -help
49
50 Print a summary of command line options.
51
52.. option:: -o <filename>
53
54 Specify the output filename.
55
56.. option:: -S
57
58 Write output in LLVM intermediate language (instead of bitcode).
59
60.. option:: -{passname}
61
62 :program:`opt` provides the ability to run any of LLVM's optimization or
63 analysis passes in any order.  The :option:`-help` option lists all the passes
64 available.  The order in which the options occur on the command line are the
65 order in which they are executed (within pass constraints).
66
67.. option:: -strip-debug
68
69 This option causes opt to strip debug information from the module before
70 applying other optimizations.  It is essentially the same as `-strip`
71 but it ensures that stripping of debug information is done first.
72
73.. option:: -verify-each
74
75 This option causes opt to add a verify pass after every pass otherwise
76 specified on the command line (including `-verify`).  This is useful
77 for cases where it is suspected that a pass is creating an invalid module but
78 it is not clear which pass is doing it.
79
80.. option:: -stats
81
82 Print statistics.
83
84.. option:: -time-passes
85
86 Record the amount of time needed for each pass and print it to standard
87 error.
88
89.. option:: -debug
90
91 If this is a debug build, this option will enable debug printouts from passes
92 which use the ``LLVM_DEBUG()`` macro.  See the `LLVM Programmer's Manual
93 <../ProgrammersManual.html>`_, section ``#DEBUG`` for more information.
94
95.. option:: -load=<plugin>
96
97 Load the dynamic object ``plugin``.  This object should register new
98 optimization or analysis passes.  Once loaded, the object will add new command
99 line options to enable various optimizations or analyses.  To see the new
100 complete list of optimizations, use the :option:`-help` and :option:`-load`
101 options together.  For example:
102
103 .. code-block:: sh
104
105     opt -load=plugin.so -help
106
107.. option:: -print-passes
108
109 Print all available passes and exit.
110
111EXIT STATUS
112-----------
113
114If :program:`opt` succeeds, it will exit with 0.  Otherwise, if an error
115occurs, it will exit with a non-zero value.
116