NAME
opt - LLVM optimizer
SYNOPSIS
opt [options] [filename]
DESCRIPTION
The opt command is the modular LLVM optimizer and analyzer. It takes
LLVM source files as input, runs the specified optimizations or
analyses 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
output 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
determine 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.
OPTIONS
-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 output
device.
-help
Print a summary of command line options.
-o filename
Specify the output filename.
-S Write output in LLVM intermediate language (instead of bitcode).
-{passname}
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 pass constraints).
-std-compile-opts
This is short hand for a standard list of compile time optimization
passes. This is typically used to optimize the output from the
llvm-gcc front end. It might be useful for other front end
compilers as well. To discover the full set of options available,
use the following command:
llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
-disable-inlining
This option is only meaningful when -std-compile-opts is given. It
simply removes the inlining pass from the standard list.
-disable-opt
This option is only meaningful when -std-compile-opts is given. It
disables most, but not all, of the -std-compile-opts. The ones that
remain are -verify, -lower-setjmp, and -funcresolve.
-strip-debug
This option causes opt to strip debug information from the module
before applying other optimizations. It is essentially the same as
-strip but it ensures that stripping of debug information is done
first.
-verify-each
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 doing it. The
combination of -std-compile-opts and -verify-each can quickly track
down this kind of problem.
-profile-info-file filename
Specify the name of the file loaded by the -profile-loader option.
-stats
Print statistics.
-time-passes
Record the amount of time needed for each pass and print it to
standard error.
-debug
If this is a debug build, this option will enable debug printouts
from passes which use the DEBUG() macro. See the LLVM Programmer's
Manual, section #DEBUG for more information.
-load=plugin
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.
EXIT STATUS
If opt succeeds, it will exit with 0. Otherwise, if an error occurs,
it will exit with a non-zero value.
AUTHORS
Maintained by the LLVM Team (<http://llvm.org>).