# LLVM: `opt` tool

### NAME

`opt`

### SYNOPSIS

`opt [options] [filename]`

### DESCRIPTION

The `opt` command is the modular LLVM optimizer. It takes LLVM bytecode as input, runs the specified optimizations on it, and then outputs the optimized LLVM bytecode.

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 no filename is specified on the command line, `opt` reads its input from standard input.

If an output filename is not specified with the `-o` option, `opt` writes its output to the standard output.

### OPTIONS

- -f
  Force overwrite. Normally, `opt` will refuse to overwrite an output file that already exists. With this option, `opt` will overwrite the output file and replace it with new bytecode.

- -help
  Print a summary of command line options.

- -o <filename>
  Specify the output filename.

- -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 Programmer's Manual for more information.

- -q
  Quiet mode. Do not print messages on whether the program was modified.

- -load <plugin.so>
  Load the dynamic object <plugin.so>. This object should register new optimization passes. Once loaded, the object will add new command line options to enable various optimizations. To see the new complete list of optimizations, use the -help and -load options together:

  `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.

### SEE ALSO

`analyze`

Maintained by the LLVM Team.