forked from OSchip/llvm-project
144 lines
4.5 KiB
Plaintext
144 lines
4.5 KiB
Plaintext
=pod
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=head1 NAME
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opt - LLVM optimizer
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=head1 SYNOPSIS
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B<opt> [I<options>] [I<filename>]
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=head1 DESCRIPTION
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The B<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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B<opt> depends on whether the B<-analyze> option is given.
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When B<-analyze> is specified, B<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 B<-analyze> is I<not> given, B<opt> attempts to produce an optimized
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output file. The optimizations available via B<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 B<-load> option. Use the B<-help> option to determine
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what optimizations you can use.
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If I<filename> is omitted from the command line or is I<->, B<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 B<-o> option, B<opt>
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writes its output to the standard output.
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=head1 OPTIONS
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=over
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=item B<-f>
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Enable binary output on terminals. Normally, B<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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B<opt> will write raw bitcode regardless of the output device.
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=item B<-help>
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Print a summary of command line options.
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=item B<-o> I<filename>
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Specify the output filename.
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=item B<-S>
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Write output in LLVM intermediate language (instead of bitcode).
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=item B<-{passname}>
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B<opt> provides the ability to run any of LLVM's optimization or analysis passes
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in any order. The B<-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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=item B<-std-compile-opts>
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This is short hand for a standard list of I<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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llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments
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=item B<-disable-inlining>
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This option is only meaningful when B<-std-compile-opts> is given. It simply
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removes the inlining pass from the standard list.
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=item B<-disable-opt>
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This option is only meaningful when B<-std-compile-opts> is given. It disables
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most, but not all, of the B<-std-compile-opts>. The ones that remain are
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B<-verify>, B<-lower-setjmp>, and B<-funcresolve>.
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=item B<-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 B<-strip> but it
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ensures that stripping of debug information is done first.
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=item B<-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 B<-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 B<-std-compile-opts> and B<-verify-each>
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can quickly track down this kind of problem.
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=item B<-profile-info-file> I<filename>
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Specify the name of the file loaded by the -profile-loader option.
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=item B<-stats>
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Print statistics.
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=item B<-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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=item B<-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 I<DEBUG()> macro. See the B<LLVM Programmer's
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Manual>, section I<#DEBUG> for more information.
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=item B<-load>=I<plugin>
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Load the dynamic object I<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 B<-help> and B<-load> options together. For example:
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opt -load=plugin.so -help
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=item B<-p>
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Print module after each transformation.
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=back
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=head1 EXIT STATUS
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If B<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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=head1 AUTHORS
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Maintained by the LLVM Team (L<http://llvm.org/>).
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=cut
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