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