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144 lines
4.8 KiB
ReStructuredText
144 lines
4.8 KiB
ReStructuredText
opt - LLVM optimizer
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====================
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SYNOPSIS
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--------
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:program:`opt` [*options*] [*filename*]
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DESCRIPTION
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-----------
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The :program:`opt` command is the modular LLVM optimizer and analyzer. It
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takes LLVM source files as input, runs the specified optimizations or analyses
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on it, and then outputs the optimized file or the analysis results. The
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function of :program:`opt` depends on whether the :option:`-analyze` option is
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given.
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When :option:`-analyze` is specified, :program:`opt` performs various analyses
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of the input source. It will usually print the results on standard output, but
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in a few cases, it will print output to standard error or generate a file with
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the analysis output, which is usually done when the output is meant for another
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program.
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While :option:`-analyze` is *not* given, :program:`opt` attempts to produce an
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optimized output file. The optimizations available via :program:`opt` depend
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upon what libraries were linked into it as well as any additional libraries
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that have been loaded with the :option:`-load` option. Use the :option:`-help`
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option to determine what optimizations you can use.
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If ``filename`` is omitted from the command line or is "``-``", :program:`opt`
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reads its input from standard input. Inputs can be in either the LLVM assembly
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language format (``.ll``) or the LLVM bitcode format (``.bc``).
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If an output filename is not specified with the :option:`-o` option,
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:program:`opt` writes its output to the standard output.
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OPTIONS
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-------
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.. option:: -f
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Enable binary output on terminals. Normally, :program:`opt` will refuse to
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write raw bitcode output if the output stream is a terminal. With this option,
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:program:`opt` will write raw bitcode regardless of the output device.
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.. option:: -help
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Print a summary of command line options.
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.. option:: -o <filename>
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Specify the output filename.
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.. option:: -S
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Write output in LLVM intermediate language (instead of bitcode).
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.. option:: -{passname}
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:program:`opt` provides the ability to run any of LLVM's optimization or
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analysis passes in any order. The :option:`-help` option lists all the passes
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available. The order in which the options occur on the command line are the
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order in which they are executed (within pass constraints).
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.. option:: -std-compile-opts
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This is short hand for a standard list of *compile time optimization* passes.
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This is typically used to optimize the output from the llvm-gcc front end. It
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might be useful for other front end compilers as well. To discover the full
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set of options available, use the following command:
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.. code-block:: sh
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llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
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.. option:: -disable-inlining
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This option is only meaningful when :option:`-std-compile-opts` is given. It
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simply removes the inlining pass from the standard list.
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.. option:: -disable-opt
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This option is only meaningful when :option:`-std-compile-opts` is given. It
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disables most, but not all, of the :option:`-std-compile-opts`. The ones that
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remain are :option:`-verify`, :option:`-lower-setjmp`, and
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:option:`-funcresolve`.
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.. option:: -strip-debug
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This option causes opt to strip debug information from the module before
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applying other optimizations. It is essentially the same as :option:`-strip`
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but it ensures that stripping of debug information is done first.
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.. option:: -verify-each
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This option causes opt to add a verify pass after every pass otherwise
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specified on the command line (including :option:`-verify`). This is useful
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for cases where it is suspected that a pass is creating an invalid module but
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it is not clear which pass is doing it. The combination of
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:option:`-std-compile-opts` and :option:`-verify-each` can quickly track down
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this kind of problem.
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.. option:: -profile-info-file <filename>
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Specify the name of the file loaded by the ``-profile-loader`` option.
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.. option:: -stats
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Print statistics.
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.. option:: -time-passes
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Record the amount of time needed for each pass and print it to standard
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error.
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.. option:: -debug
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If this is a debug build, this option will enable debug printouts from passes
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which use the ``DEBUG()`` macro. See the `LLVM Programmer's Manual
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<../ProgrammersManual.html>`_, section ``#DEBUG`` for more information.
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.. option:: -load=<plugin>
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Load the dynamic object ``plugin``. This object should register new
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optimization or analysis passes. Once loaded, the object will add new command
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line options to enable various optimizations or analyses. To see the new
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complete list of optimizations, use the :option:`-help` and :option:`-load`
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options together. For example:
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.. code-block:: sh
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opt -load=plugin.so -help
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.. option:: -p
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Print module after each transformation.
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EXIT STATUS
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-----------
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If :program:`opt` succeeds, it will exit with 0. Otherwise, if an error
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occurs, it will exit with a non-zero value.
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