OPT(1) LLVM OPT(1)
opt - LLVM optimizer
opt [options] [filename]
The opt command is the modular LLVM optimizer and analyzer. It takes
LLVM source files as input, runs the specified optimizations or analy-
ses on it, and then outputs the optimized file or the analysis results.
The function of opt depends on whether the -analyze option is given.
When -analyze is specified, opt performs various analyses of the input
source. It will usually print the results on standard output, but in a
few cases, it will print output to standard error or generate a file
with the analysis output, which is usually done when the output is
meant for another program.
While -analyze is not given, opt attempts to produce an optimized out-
put file. The optimizations available via opt depend upon what
libraries were linked into it as well as any additional libraries that
have been loaded with the -load option. Use the -help option to deter-
mine what optimizations you can use.
If filename is omitted from the command line or is "-", opt reads its
input from standard input. Inputs can be in either the LLVM assembly
language format (.ll) or the LLVM bitcode format (.bc).
If an output filename is not specified with the -o option, opt writes
its output to the standard output.
-f Enable binary output on terminals. Normally, opt will refuse to
write raw bitcode output if the output stream is a terminal.
With this option, opt will write raw bitcode regardless of the
-help Print a summary of command line options.
Specify the output filename.
-S Write output in LLVM intermediate language (instead of bitcode).
opt provides the ability to run any of LLVM's optimization or
analysis passes in any order. The -help option lists all the
passes available. The order in which the options occur on the
command line are the order in which they are executed (within
This option simply removes the inlining pass from the standard
This option is only meaningful when -std-link-opts is given. It
disables most passes.
This option causes opt to strip debug information from the mod-
ule before applying other optimizations. It is essentially the
same as -strip but it ensures that stripping of debug informa-
tion is done first.
This option causes opt to add a verify pass after every pass
otherwise specified on the command line (including -verify).
This is useful for cases where it is suspected that a pass is
creating an invalid module but it is not clear which pass is
-stats Print statistics.
Record the amount of time needed for each pass and print it to
-debug If this is a debug build, this option will enable debug print-
outs from passes which use the DEBUG() macro. See the LLVM Pro-
grammer's Manual, section #DEBUG for more information.
Load the dynamic object plugin. This object should register new
optimization or analysis passes. Once loaded, the object will
add new command line options to enable various optimizations or
analyses. To see the new complete list of optimizations, use
the -help and -load options together. For example:
opt -load=plugin.so -help
-p Print module after each transformation.
If opt succeeds, it will exit with 0. Otherwise, if an error occurs,
it will exit with a non-zero value.
Maintained by The LLVM Team (http://llvm.org/).
2003-2016, LLVM Project
3.7 2016-03-07 OPT(1)