1opt - LLVM optimizer
2====================
3
4
5SYNOPSIS
6--------
7
8
9**opt** [*options*] [*filename*]
10
11
12DESCRIPTION
13-----------
14
15
16The **opt** command is the modular LLVM optimizer and analyzer.  It takes LLVM
17source files as input, runs the specified optimizations or analyses on it, and then
18outputs the optimized file or the analysis results.  The function of
19**opt** depends on whether the **-analyze** option is given.
20
21When **-analyze** is specified, **opt** performs various analyses of the input
22source.  It will usually print the results on standard output, but in a few
23cases, it will print output to standard error or generate a file with the
24analysis output, which is usually done when the output is meant for another
25program.
26
27While **-analyze** is *not* given, **opt** attempts to produce an optimized
28output file.  The optimizations available via **opt** depend upon what
29libraries were linked into it as well as any additional libraries that have
30been loaded with the **-load** option.  Use the **-help** option to determine
31what optimizations you can use.
32
33If *filename* is omitted from the command line or is *-*, **opt** reads its
34input from standard input. Inputs can be in either the LLVM assembly language
35format (.ll) or the LLVM bitcode format (.bc).
36
37If an output filename is not specified with the **-o** option, **opt**
38writes its output to the standard output.
39
40
41OPTIONS
42-------
43
44
45
46**-f**
47
48 Enable binary output on terminals.  Normally, **opt** will refuse to
49 write raw bitcode output if the output stream is a terminal. With this option,
50 **opt** will write raw bitcode regardless of the output device.
51
52
53
54**-help**
55
56 Print a summary of command line options.
57
58
59
60**-o** *filename*
61
62 Specify the output filename.
63
64
65
66**-S**
67
68 Write output in LLVM intermediate language (instead of bitcode).
69
70
71
72**-{passname}**
73
74 **opt** provides the ability to run any of LLVM's optimization or analysis passes
75 in any order. The **-help** option lists all the passes available. The order in
76 which the options occur on the command line are the order in which they are
77 executed (within pass constraints).
78
79
80
81**-std-compile-opts**
82
83 This is short hand for a standard list of *compile time optimization* passes.
84 This is typically used to optimize the output from the llvm-gcc front end. It
85 might be useful for other front end compilers as well. To discover the full set
86 of options available, use the following command:
87
88
89 .. code-block:: sh
90
91     llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
92
93
94
95
96**-disable-inlining**
97
98 This option is only meaningful when **-std-compile-opts** is given. It simply
99 removes the inlining pass from the standard list.
100
101
102
103**-disable-opt**
104
105 This option is only meaningful when **-std-compile-opts** is given. It disables
106 most, but not all, of the **-std-compile-opts**. The ones that remain are
107 **-verify**, **-lower-setjmp**, and **-funcresolve**.
108
109
110
111**-strip-debug**
112
113 This option causes opt to strip debug information from the module before
114 applying other optimizations. It is essentially the same as **-strip** but it
115 ensures that stripping of debug information is done first.
116
117
118
119**-verify-each**
120
121 This option causes opt to add a verify pass after every pass otherwise specified
122 on the command line (including **-verify**).  This is useful for cases where it
123 is suspected that a pass is creating an invalid module but it is not clear which
124 pass is doing it. The combination of **-std-compile-opts** and **-verify-each**
125 can quickly track down this kind of problem.
126
127
128
129**-profile-info-file** *filename*
130
131 Specify the name of the file loaded by the -profile-loader option.
132
133
134
135**-stats**
136
137 Print statistics.
138
139
140
141**-time-passes**
142
143 Record the amount of time needed for each pass and print it to standard
144 error.
145
146
147
148**-debug**
149
150 If this is a debug build, this option will enable debug printouts
151 from passes which use the *DEBUG()* macro.  See the **LLVM Programmer's
152 Manual**, section *#DEBUG* for more information.
153
154
155
156**-load**\ =\ *plugin*
157
158 Load the dynamic object *plugin*.  This object should register new optimization
159 or analysis passes. Once loaded, the object will add new command line options to
160 enable various optimizations or analyses.  To see the new complete list of
161 optimizations, use the **-help** and **-load** options together. For example:
162
163
164 .. code-block:: sh
165
166     opt -load=plugin.so -help
167
168
169
170
171**-p**
172
173 Print module after each transformation.
174
175
176
177
178EXIT STATUS
179-----------
180
181
182If **opt** succeeds, it will exit with 0.  Otherwise, if an error
183occurs, it will exit with a non-zero value.
184