1 opt - LLVM optimizer 2 ==================== 3 4 SYNOPSIS 5 -------- 6 7 :program:`opt` [*options*] [*filename*] 8 9 DESCRIPTION 10 ----------- 11 12 The :program:`opt` command is the modular LLVM optimizer and analyzer. It 13 takes LLVM source files as input, runs the specified optimizations or analyses 14 on it, and then outputs the optimized file or the analysis results. The 15 function of :program:`opt` depends on whether the :option:`-analyze` option is 16 given. 17 18 When :option:`-analyze` is specified, :program:`opt` performs various analyses 19 of the input source. It will usually print the results on standard output, but 20 in a few cases, it will print output to standard error or generate a file with 21 the analysis output, which is usually done when the output is meant for another 22 program. 23 24 While :option:`-analyze` is *not* given, :program:`opt` attempts to produce an 25 optimized output file. The optimizations available via :program:`opt` depend 26 upon what libraries were linked into it as well as any additional libraries 27 that have been loaded with the :option:`-load` option. Use the :option:`-help` 28 option to determine what optimizations you can use. 29 30 If ``filename`` is omitted from the command line or is "``-``", :program:`opt` 31 reads its input from standard input. Inputs can be in either the LLVM assembly 32 language format (``.ll``) or the LLVM bitcode format (``.bc``). 33 34 If an output filename is not specified with the :option:`-o` option, 35 :program:`opt` writes its output to the standard output. 36 37 OPTIONS 38 ------- 39 40 .. option:: -f 41 42 Enable binary output on terminals. Normally, :program:`opt` will refuse to 43 write raw bitcode output if the output stream is a terminal. With this option, 44 :program:`opt` will write raw bitcode regardless of the output device. 45 46 .. option:: -help 47 48 Print a summary of command line options. 49 50 .. option:: -o <filename> 51 52 Specify the output filename. 53 54 .. option:: -S 55 56 Write output in LLVM intermediate language (instead of bitcode). 57 58 .. option:: -{passname} 59 60 :program:`opt` provides the ability to run any of LLVM's optimization or 61 analysis passes in any order. The :option:`-help` option lists all the passes 62 available. The order in which the options occur on the command line are the 63 order in which they are executed (within pass constraints). 64 65 .. option:: -std-compile-opts 66 67 This is short hand for a standard list of *compile time optimization* passes. 68 This is typically used to optimize the output from the llvm-gcc front end. It 69 might be useful for other front end compilers as well. To discover the full 70 set of options available, use the following command: 71 72 .. code-block:: sh 73 74 llvm-as < /dev/null | opt -std-compile-opts -disable-output -debug-pass=Arguments 75 76 .. option:: -disable-inlining 77 78 This option is only meaningful when :option:`-std-compile-opts` is given. It 79 simply removes the inlining pass from the standard list. 80 81 .. option:: -disable-opt 82 83 This option is only meaningful when :option:`-std-compile-opts` is given. It 84 disables most, but not all, of the :option:`-std-compile-opts`. The ones that 85 remain are :option:`-verify`, :option:`-lower-setjmp`, and 86 :option:`-funcresolve`. 87 88 .. option:: -strip-debug 89 90 This option causes opt to strip debug information from the module before 91 applying other optimizations. It is essentially the same as :option:`-strip` 92 but it ensures that stripping of debug information is done first. 93 94 .. option:: -verify-each 95 96 This option causes opt to add a verify pass after every pass otherwise 97 specified on the command line (including :option:`-verify`). This is useful 98 for cases where it is suspected that a pass is creating an invalid module but 99 it is not clear which pass is doing it. The combination of 100 :option:`-std-compile-opts` and :option:`-verify-each` can quickly track down 101 this kind of problem. 102 103 .. option:: -profile-info-file <filename> 104 105 Specify the name of the file loaded by the ``-profile-loader`` option. 106 107 .. option:: -stats 108 109 Print statistics. 110 111 .. option:: -time-passes 112 113 Record the amount of time needed for each pass and print it to standard 114 error. 115 116 .. option:: -debug 117 118 If this is a debug build, this option will enable debug printouts from passes 119 which use the ``DEBUG()`` macro. See the `LLVM Programmer's Manual 120 <../ProgrammersManual.html>`_, section ``#DEBUG`` for more information. 121 122 .. option:: -load=<plugin> 123 124 Load the dynamic object ``plugin``. This object should register new 125 optimization or analysis passes. Once loaded, the object will add new command 126 line options to enable various optimizations or analyses. To see the new 127 complete list of optimizations, use the :option:`-help` and :option:`-load` 128 options together. For example: 129 130 .. code-block:: sh 131 132 opt -load=plugin.so -help 133 134 .. option:: -p 135 136 Print module after each transformation. 137 138 EXIT STATUS 139 ----------- 140 141 If :program:`opt` succeeds, it will exit with 0. Otherwise, if an error 142 occurs, it will exit with a non-zero value. 143 144
