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1opt - LLVM optimizer
2====================
3
4SYNOPSIS
5--------
6
7:program:`opt` [*options*] [*filename*]
8
9DESCRIPTION
10-----------
11
12The :program:`opt` command is the modular LLVM optimizer and analyzer.  It
13takes LLVM source files as input, runs the specified optimizations or analyses
14on it, and then outputs the optimized file or the analysis results.  The
15function of :program:`opt` depends on whether the :option:`-analyze` option is
16given.
17
18When :option:`-analyze` is specified, :program:`opt` performs various analyses
19of the input source.  It will usually print the results on standard output, but
20in a few cases, it will print output to standard error or generate a file with
21the analysis output, which is usually done when the output is meant for another
22program.
23
24While :option:`-analyze` is *not* given, :program:`opt` attempts to produce an
25optimized output file.  The optimizations available via :program:`opt` depend
26upon what libraries were linked into it as well as any additional libraries
27that have been loaded with the :option:`-load` option.  Use the :option:`-help`
28option to determine what optimizations you can use.
29
30If ``filename`` is omitted from the command line or is "``-``", :program:`opt`
31reads its input from standard input.  Inputs can be in either the LLVM assembly
32language format (``.ll``) or the LLVM bitcode format (``.bc``).
33
34If an output filename is not specified with the :option:`-o` option,
35:program:`opt` writes its output to the standard output.
36
37OPTIONS
38-------
39
40.. option:: -f
41
42 Enable binary output on terminals.  Normally, :program:`opt` will refuse to
43 write raw bitcode output if the output stream is a terminal.  With this option,
44 :program:`opt` will write raw bitcode regardless of the output device.
45
46.. option:: -help
47
48 Print a summary of command line options.
49
50.. option:: -o <filename>
51
52 Specify the output filename.
53
54.. option:: -S
55
56 Write output in LLVM intermediate language (instead of bitcode).
57
58.. option:: -{passname}
59
60 :program:`opt` provides the ability to run any of LLVM's optimization or
61 analysis passes in any order.  The :option:`-help` option lists all the passes
62 available.  The order in which the options occur on the command line are the
63 order in which they are executed (within pass constraints).
64
65.. option:: -std-compile-opts
66
67 This is short hand for a standard list of *compile time optimization* passes.
68 This is typically used to optimize the output from the llvm-gcc front end.  It
69 might be useful for other front end compilers as well.  To discover the full
70 set of options available, use the following command:
71
72 .. code-block:: sh
73
74     llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
75
76.. option:: -disable-inlining
77
78 This option is only meaningful when :option:`-std-compile-opts` is given.  It
79 simply removes the inlining pass from the standard list.
80
81.. option:: -disable-opt
82
83 This option is only meaningful when :option:`-std-compile-opts` is given.  It
84 disables most, but not all, of the :option:`-std-compile-opts`.  The ones that
85 remain are :option:`-verify`, :option:`-lower-setjmp`, and
86 :option:`-funcresolve`.
87
88.. option:: -strip-debug
89
90 This option causes opt to strip debug information from the module before
91 applying other optimizations.  It is essentially the same as :option:`-strip`
92 but it ensures that stripping of debug information is done first.
93
94.. option:: -verify-each
95
96 This option causes opt to add a verify pass after every pass otherwise
97 specified on the command line (including :option:`-verify`).  This is useful
98 for cases where it is suspected that a pass is creating an invalid module but
99 it is not clear which pass is doing it.  The combination of
100 :option:`-std-compile-opts` and :option:`-verify-each` can quickly track down
101 this kind of problem.
102
103.. option:: -profile-info-file <filename>
104
105 Specify the name of the file loaded by the ``-profile-loader`` option.
106
107.. option:: -stats
108
109 Print statistics.
110
111.. option:: -time-passes
112
113 Record the amount of time needed for each pass and print it to standard
114 error.
115
116.. option:: -debug
117
118 If this is a debug build, this option will enable debug printouts from passes
119 which use the ``DEBUG()`` macro.  See the `LLVM Programmer's Manual
120 <../ProgrammersManual.html>`_, section ``#DEBUG`` for more information.
121
122.. option:: -load=<plugin>
123
124 Load the dynamic object ``plugin``.  This object should register new
125 optimization or analysis passes.  Once loaded, the object will add new command
126 line options to enable various optimizations or analyses.  To see the new
127 complete list of optimizations, use the :option:`-help` and :option:`-load`
128 options together.  For example:
129
130 .. code-block:: sh
131
132     opt -load=plugin.so -help
133
134.. option:: -p
135
136 Print module after each transformation.
137
138EXIT STATUS
139-----------
140
141If :program:`opt` succeeds, it will exit with 0.  Otherwise, if an error
142occurs, it will exit with a non-zero value.
143
144