


OPT(1)                  LLVM Command Guide                 OPT(1)


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



CVS                         2010-05-06                          1





OPT(1)                  LLVM Command Guide                 OPT(1)


           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




CVS                         2010-05-06                          2





OPT(1)                  LLVM Command Guide                 OPT(1)


       -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>).

















































CVS                         2010-05-06                          3


