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<?xml version="1.0" encoding="utf-8" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="generator" content="Docutils 0.6: http://docutils.sourceforge.net/" />
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<title>Customizing LLVMC: Reference Manual</title>
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<link rel="stylesheet" href="llvm.css" type="text/css" />
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</head>
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<body>
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<div class="document" id="customizing-llvmc-reference-manual">
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<h1 class="title">Customizing LLVMC: Reference Manual</h1>
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<!-- This file was automatically generated by rst2html.
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Please do not edit directly!
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The ReST source lives in the directory 'tools/llvmc/doc'. -->
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<div class="contents topic" id="contents">
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<p class="topic-title first">Contents</p>
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<ul class="simple">
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<li><a class="reference internal" href="#introduction" id="id7">Introduction</a></li>
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<li><a class="reference internal" href="#compiling-with-llvmc" id="id8">Compiling with <tt class="docutils literal">llvmc</tt></a></li>
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<li><a class="reference internal" href="#predefined-options" id="id9">Predefined options</a></li>
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<li><a class="reference internal" href="#compiling-llvmc-based-drivers" id="id10">Compiling LLVMC-based drivers</a></li>
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<li><a class="reference internal" href="#customizing-llvmc-the-compilation-graph" id="id11">Customizing LLVMC: the compilation graph</a></li>
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<li><a class="reference internal" href="#describing-options" id="id12">Describing options</a></li>
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<li><a class="reference internal" href="#conditional-evaluation" id="id13">Conditional evaluation</a></li>
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<li><a class="reference internal" href="#writing-a-tool-description" id="id14">Writing a tool description</a><ul>
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<li><a class="reference internal" href="#id4" id="id15">Actions</a></li>
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</ul>
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</li>
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<li><a class="reference internal" href="#language-map" id="id16">Language map</a></li>
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<li><a class="reference internal" href="#option-preprocessor" id="id17">Option preprocessor</a></li>
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<li><a class="reference internal" href="#more-advanced-topics" id="id18">More advanced topics</a><ul>
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<li><a class="reference internal" href="#hooks-and-environment-variables" id="id19">Hooks and environment variables</a></li>
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<li><a class="reference internal" href="#debugging" id="id20">Debugging</a></li>
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<li><a class="reference internal" href="#conditioning-on-the-executable-name" id="id21">Conditioning on the executable name</a></li>
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</ul>
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</li>
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</ul>
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</div>
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<div class="doc_author">
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<p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p>
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</div><div class="section" id="introduction">
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<h1><a class="toc-backref" href="#id7">Introduction</a></h1>
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<p>LLVMC is a generic compiler driver, designed to be customizable and
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extensible. It plays the same role for LLVM as the <tt class="docutils literal">gcc</tt> program does for
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GCC - LLVMC's job is essentially to transform a set of input files into a set of
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targets depending on configuration rules and user options. What makes LLVMC
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different is that these transformation rules are completely customizable - in
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fact, LLVMC knows nothing about the specifics of transformation (even the
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command-line options are mostly not hard-coded) and regards the transformation
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structure as an abstract graph. The structure of this graph is described in
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high-level TableGen code, from which an efficient C++ representation is
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automatically derived. This makes it possible to adapt LLVMC for other
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purposes - for example, as a build tool for game resources.</p>
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<p>Because LLVMC employs <a class="reference external" href="http://llvm.org/docs/TableGenFundamentals.html">TableGen</a> as its configuration language, you
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need to be familiar with it to customize LLVMC.</p>
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</div>
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<div class="section" id="compiling-with-llvmc">
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<h1><a class="toc-backref" href="#id8">Compiling with <tt class="docutils literal">llvmc</tt></a></h1>
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<p>LLVMC tries hard to be as compatible with <tt class="docutils literal">gcc</tt> as possible,
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although there are some small differences. Most of the time, however,
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you shouldn't be able to notice them:</p>
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<pre class="literal-block">
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$ # This works as expected:
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$ llvmc -O3 -Wall hello.cpp
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$ ./a.out
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hello
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</pre>
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<p>One nice feature of LLVMC is that one doesn't have to distinguish between
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different compilers for different languages (think <tt class="docutils literal">g++</tt> vs. <tt class="docutils literal">gcc</tt>) - the
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right toolchain is chosen automatically based on input language names (which
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are, in turn, determined from file extensions). If you want to force files
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ending with ".c" to compile as C++, use the <tt class="docutils literal"><span class="pre">-x</span></tt> option, just like you would
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do it with <tt class="docutils literal">gcc</tt>:</p>
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<pre class="literal-block">
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$ # hello.c is really a C++ file
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$ llvmc -x c++ hello.c
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$ ./a.out
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hello
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</pre>
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<p>On the other hand, when using LLVMC as a linker to combine several C++
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object files you should provide the <tt class="docutils literal"><span class="pre">--linker</span></tt> option since it's
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impossible for LLVMC to choose the right linker in that case:</p>
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<pre class="literal-block">
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$ llvmc -c hello.cpp
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$ llvmc hello.o
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[A lot of link-time errors skipped]
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$ llvmc --linker=c++ hello.o
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$ ./a.out
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hello
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</pre>
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<p>By default, LLVMC uses <tt class="docutils literal"><span class="pre">llvm-gcc</span></tt> to compile the source code. It is also
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possible to choose the <tt class="docutils literal">clang</tt> compiler with the <tt class="docutils literal"><span class="pre">-clang</span></tt> option.</p>
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</div>
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<div class="section" id="predefined-options">
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<h1><a class="toc-backref" href="#id9">Predefined options</a></h1>
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<p>LLVMC has some built-in options that can't be overridden in the TableGen code:</p>
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<ul class="simple">
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<li><tt class="docutils literal"><span class="pre">-o</span> FILE</tt> - Output file name.</li>
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<li><tt class="docutils literal"><span class="pre">-x</span> LANGUAGE</tt> - Specify the language of the following input files
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until the next -x option.</li>
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<li><tt class="docutils literal"><span class="pre">-v</span></tt> - Enable verbose mode, i.e. print out all executed commands.</li>
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<li><tt class="docutils literal"><span class="pre">--save-temps</span></tt> - Write temporary files to the current directory and do not
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delete them on exit. This option can also take an argument: the
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<tt class="docutils literal"><span class="pre">--save-temps=obj</span></tt> switch will write files into the directory specified with
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the <tt class="docutils literal"><span class="pre">-o</span></tt> option. The <tt class="docutils literal"><span class="pre">--save-temps=cwd</span></tt> and <tt class="docutils literal"><span class="pre">--save-temps</span></tt> switches are
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both synonyms for the default behaviour.</li>
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<li><tt class="docutils literal"><span class="pre">--temp-dir</span> DIRECTORY</tt> - Store temporary files in the given directory. This
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directory is deleted on exit unless <tt class="docutils literal"><span class="pre">--save-temps</span></tt> is specified. If
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<tt class="docutils literal"><span class="pre">--save-temps=obj</span></tt> is also specified, <tt class="docutils literal"><span class="pre">--temp-dir</span></tt> is given the
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precedence.</li>
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<li><tt class="docutils literal"><span class="pre">--check-graph</span></tt> - Check the compilation for common errors like mismatched
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output/input language names, multiple default edges and cycles. Exit with code
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zero if no errors were found, and return the number of found errors
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otherwise. Hidden option, useful for debugging.</li>
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<li><tt class="docutils literal"><span class="pre">--view-graph</span></tt> - Show a graphical representation of the compilation graph
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and exit. Requires that you have <tt class="docutils literal">dot</tt> and <tt class="docutils literal">gv</tt> programs installed. Hidden
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option, useful for debugging.</li>
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<li><tt class="docutils literal"><span class="pre">--write-graph</span></tt> - Write a <tt class="docutils literal"><span class="pre">compilation-graph.dot</span></tt> file in the current
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directory with the compilation graph description in Graphviz format (identical
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to the file used by the <tt class="docutils literal"><span class="pre">--view-graph</span></tt> option). The <tt class="docutils literal"><span class="pre">-o</span></tt> option can be
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used to set the output file name. Hidden option, useful for debugging.</li>
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<li><tt class="docutils literal"><span class="pre">--help</span></tt>, <tt class="docutils literal"><span class="pre">--help-hidden</span></tt>, <tt class="docutils literal"><span class="pre">--version</span></tt> - These options have
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their standard meaning.</li>
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</ul>
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</div>
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<div class="section" id="compiling-llvmc-based-drivers">
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<h1><a class="toc-backref" href="#id10">Compiling LLVMC-based drivers</a></h1>
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<p>It's easiest to start working on your own LLVMC driver by copying the skeleton
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project which lives under <tt class="docutils literal">$LLVMC_DIR/examples/Skeleton</tt>:</p>
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<pre class="literal-block">
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$ cd $LLVMC_DIR/examples
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$ cp -r Skeleton MyDriver
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$ cd MyDriver
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$ ls
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AutoGenerated.td Hooks.cpp Main.cpp Makefile
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</pre>
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<p>As you can see, our basic driver consists of only three files (not counting the
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build script). <tt class="docutils literal">AutoGenerated.td</tt> contains TableGen description of the
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compilation graph; its format is documented in the following
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sections. <tt class="docutils literal">Hooks.cpp</tt> is an empty file that should be used for hook
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definitions (see <a class="reference internal" href="#hooks">below</a>). <tt class="docutils literal">Main.cpp</tt> is just a helper used to compile the
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auto-generated C++ code produced from TableGen source.</p>
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<p>The first thing that you should do is to change the <tt class="docutils literal">LLVMC_BASED_DRIVER</tt>
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variable in the <tt class="docutils literal">Makefile</tt>:</p>
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<pre class="literal-block">
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LLVMC_BASED_DRIVER=MyDriver
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</pre>
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<p>It can also be a good idea to put your TableGen code into a file with a less
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generic name:</p>
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<pre class="literal-block">
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$ touch MyDriver.td
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$ vim AutoGenerated.td
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[...]
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include "MyDriver.td"
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</pre>
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<p>If you have more than one TableGen source file, they all should be included from
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<tt class="docutils literal">AutoGenerated.td</tt>, since this file is used by the build system to generate
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C++ code.</p>
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<p>To build your driver, just <tt class="docutils literal">cd</tt> to its source directory and run <tt class="docutils literal">make</tt>. The
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resulting executable will be put into <tt class="docutils literal"><span class="pre">$LLVM_OBJ_DIR/$(BuildMode)/bin</span></tt>.</p>
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<p>If you're compiling LLVM with different source and object directories, then you
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must perform the following additional steps before running <tt class="docutils literal">make</tt>:</p>
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<pre class="literal-block">
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# LLVMC_SRC_DIR = $LLVM_SRC_DIR/tools/llvmc/
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# LLVMC_OBJ_DIR = $LLVM_OBJ_DIR/tools/llvmc/
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$ mkdir $LLVMC_OBJ_DIR/examples/MyDriver/
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$ cp $LLVMC_SRC_DIR/examples/MyDriver/Makefile \
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$LLVMC_OBJ_DIR/examples/MyDriver/
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$ cd $LLVMC_OBJ_DIR/examples/MyDriver
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$ make
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</pre>
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</div>
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<div class="section" id="customizing-llvmc-the-compilation-graph">
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<h1><a class="toc-backref" href="#id11">Customizing LLVMC: the compilation graph</a></h1>
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<p>Each TableGen configuration file should include the common definitions:</p>
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<pre class="literal-block">
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include "llvm/CompilerDriver/Common.td"
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</pre>
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<p>Internally, LLVMC stores information about possible source transformations in
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form of a graph. Nodes in this graph represent tools, and edges between two
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nodes represent a transformation path. A special "root" node is used to mark
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entry points for the transformations. LLVMC also assigns a weight to each edge
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(more on this later) to choose between several alternative edges.</p>
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<p>The definition of the compilation graph (see file <tt class="docutils literal">llvmc/src/Base.td</tt> for an
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example) is just a list of edges:</p>
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<pre class="literal-block">
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def CompilationGraph : CompilationGraph<[
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Edge<"root", "llvm_gcc_c">,
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Edge<"root", "llvm_gcc_assembler">,
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...
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Edge<"llvm_gcc_c", "llc">,
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Edge<"llvm_gcc_cpp", "llc">,
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...
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OptionalEdge<"llvm_gcc_c", "opt", (case (switch_on "opt"),
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(inc_weight))>,
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OptionalEdge<"llvm_gcc_cpp", "opt", (case (switch_on "opt"),
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(inc_weight))>,
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...
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OptionalEdge<"llvm_gcc_assembler", "llvm_gcc_cpp_linker",
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(case (input_languages_contain "c++"), (inc_weight),
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(or (parameter_equals "linker", "g++"),
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(parameter_equals "linker", "c++")), (inc_weight))>,
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...
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]>;
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</pre>
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<p>As you can see, the edges can be either default or optional, where optional
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edges are differentiated by an additional <tt class="docutils literal">case</tt> expression used to calculate
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the weight of this edge. Notice also that we refer to tools via their names (as
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strings). This makes it possible to add edges to an existing compilation graph
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without having to know about all tool definitions used in the graph.</p>
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<p>The default edges are assigned a weight of 1, and optional edges get a weight of
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0 + 2*N where N is the number of tests that evaluated to true in the <tt class="docutils literal">case</tt>
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expression. It is also possible to provide an integer parameter to
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<tt class="docutils literal">inc_weight</tt> and <tt class="docutils literal">dec_weight</tt> - in this case, the weight is increased (or
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decreased) by the provided value instead of the default 2. Default weight of an
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optional edge can be changed by using the <tt class="docutils literal">default</tt> clause of the <tt class="docutils literal">case</tt>
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construct.</p>
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<p>When passing an input file through the graph, LLVMC picks the edge with the
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maximum weight. To avoid ambiguity, there should be only one default edge
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between two nodes (with the exception of the root node, which gets a special
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treatment - there you are allowed to specify one default edge <em>per language</em>).</p>
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<p>When multiple compilation graphs are defined, they are merged together. Multiple
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edges with the same end nodes are not allowed (i.e. the graph is not a
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multigraph), and will lead to a compile-time error.</p>
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<p>To get a visual representation of the compilation graph (useful for debugging),
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run <tt class="docutils literal">llvmc <span class="pre">--view-graph</span></tt>. You will need <tt class="docutils literal">dot</tt> and <tt class="docutils literal">gsview</tt> installed for
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this to work properly.</p>
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</div>
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<div class="section" id="describing-options">
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<h1><a class="toc-backref" href="#id12">Describing options</a></h1>
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<p>Command-line options supported by the driver are defined by using an
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<tt class="docutils literal">OptionList</tt>:</p>
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<pre class="literal-block">
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def Options : OptionList<[
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(switch_option "E", (help "Help string")),
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(alias_option "quiet", "q")
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...
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]>;
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</pre>
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<p>As you can see, the option list is just a list of DAGs, where each DAG is an
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option description consisting of the option name and some properties. More than
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one option list can be defined (they are all merged together in the end), which
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can be handy if one wants to separate option groups syntactically.</p>
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<ul>
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<li><p class="first">Possible option types:</p>
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<blockquote>
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<ul class="simple">
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<li><tt class="docutils literal">switch_option</tt> - a simple boolean switch without arguments, for example
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<tt class="docutils literal"><span class="pre">-O2</span></tt> or <tt class="docutils literal"><span class="pre">-time</span></tt>. At most one occurrence is allowed by default.</li>
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<li><tt class="docutils literal">parameter_option</tt> - option that takes one argument, for example
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<tt class="docutils literal"><span class="pre">-std=c99</span></tt>. It is also allowed to use spaces instead of the equality
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sign: <tt class="docutils literal"><span class="pre">-std</span> c99</tt>. At most one occurrence is allowed.</li>
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<li><tt class="docutils literal">parameter_list_option</tt> - same as the above, but more than one option
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occurrence is allowed.</li>
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<li><tt class="docutils literal">prefix_option</tt> - same as the parameter_option, but the option name and
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argument do not have to be separated. Example: <tt class="docutils literal"><span class="pre">-ofile</span></tt>. This can be also
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specified as <tt class="docutils literal"><span class="pre">-o</span> file</tt>; however, <tt class="docutils literal"><span class="pre">-o=file</span></tt> will be parsed incorrectly
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(<tt class="docutils literal">=file</tt> will be interpreted as option value). At most one occurrence is
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allowed.</li>
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<li><tt class="docutils literal">prefix_list_option</tt> - same as the above, but more than one occurrence of
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the option is allowed; example: <tt class="docutils literal"><span class="pre">-lm</span> <span class="pre">-lpthread</span></tt>.</li>
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<li><tt class="docutils literal">alias_option</tt> - a special option type for creating aliases. Unlike other
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option types, aliases are not allowed to have any properties besides the
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aliased option name.
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Usage example: <tt class="docutils literal">(alias_option "preprocess", "E")</tt></li>
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<li><tt class="docutils literal">switch_list_option</tt> - like <tt class="docutils literal">switch_option</tt> with the <tt class="docutils literal">zero_or_more</tt>
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property, but remembers how many times the switch was turned on. Useful
|
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mostly for forwarding. Example: when <tt class="docutils literal"><span class="pre">-foo</span></tt> is a switch option (with the
|
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<tt class="docutils literal">zero_or_more</tt> property), the command <tt class="docutils literal">driver <span class="pre">-foo</span> <span class="pre">-foo</span></tt> is forwarded
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as <tt class="docutils literal"><span class="pre">some-tool</span> <span class="pre">-foo</span></tt>, but when <tt class="docutils literal"><span class="pre">-foo</span></tt> is a switch list, the same command
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is forwarded as <tt class="docutils literal"><span class="pre">some-tool</span> <span class="pre">-foo</span> <span class="pre">-foo</span></tt>.</li>
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</ul>
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</blockquote>
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</li>
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<li><p class="first">Possible option properties:</p>
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<blockquote>
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<ul class="simple">
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<li><tt class="docutils literal">help</tt> - help string associated with this option. Used for <tt class="docutils literal"><span class="pre">--help</span></tt>
|
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output.</li>
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<li><tt class="docutils literal">required</tt> - this option must be specified exactly once (or, in case of
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the list options without the <tt class="docutils literal">multi_val</tt> property, at least
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once). Incompatible with <tt class="docutils literal">optional</tt> and <tt class="docutils literal">one_or_more</tt>.</li>
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<li><tt class="docutils literal">optional</tt> - the option can be specified either zero times or exactly
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once. The default for switch options. Useful only for list options in
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conjunction with <tt class="docutils literal">multi_val</tt>. Incompatible with <tt class="docutils literal">required</tt>,
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<tt class="docutils literal">zero_or_more</tt> and <tt class="docutils literal">one_or_more</tt>.</li>
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<li><tt class="docutils literal">one_or_more</tt> - the option must be specified at least once. Can be useful
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to allow switch options be both obligatory and be specified multiple
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times. For list options is useful only in conjunction with <tt class="docutils literal">multi_val</tt>;
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for ordinary it is synonymous with <tt class="docutils literal">required</tt>. Incompatible with
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<tt class="docutils literal">required</tt>, <tt class="docutils literal">optional</tt> and <tt class="docutils literal">zero_or_more</tt>.</li>
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<li><tt class="docutils literal">zero_or_more</tt> - the option can be specified zero or more times. Useful
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to allow a single switch option to be specified more than
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once. Incompatible with <tt class="docutils literal">required</tt>, <tt class="docutils literal">optional</tt> and <tt class="docutils literal">one_or_more</tt>.</li>
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<li><tt class="docutils literal">hidden</tt> - the description of this option will not appear in
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the <tt class="docutils literal"><span class="pre">--help</span></tt> output (but will appear in the <tt class="docutils literal"><span class="pre">--help-hidden</span></tt>
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output).</li>
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<li><tt class="docutils literal">really_hidden</tt> - the option will not be mentioned in any help
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output.</li>
|
|
<li><tt class="docutils literal">comma_separated</tt> - Indicates that any commas specified for an option's
|
|
value should be used to split the value up into multiple values for the
|
|
option. This property is valid only for list options. In conjunction with
|
|
<tt class="docutils literal">forward_value</tt> can be used to implement option forwarding in style of
|
|
gcc's <tt class="docutils literal"><span class="pre">-Wa,</span></tt>.</li>
|
|
<li><tt class="docutils literal">multi_val n</tt> - this option takes <em>n</em> arguments (can be useful in some
|
|
special cases). Usage example: <tt class="docutils literal">(parameter_list_option "foo", (multi_val
|
|
3))</tt>; the command-line syntax is '-foo a b c'. Only list options can have
|
|
this attribute; you can, however, use the <tt class="docutils literal">one_or_more</tt>, <tt class="docutils literal">optional</tt>
|
|
and <tt class="docutils literal">required</tt> properties.</li>
|
|
<li><tt class="docutils literal">init</tt> - this option has a default value, either a string (if it is a
|
|
parameter), or a boolean (if it is a switch; as in C++, boolean constants
|
|
are called <tt class="docutils literal">true</tt> and <tt class="docutils literal">false</tt>). List options can't have <tt class="docutils literal">init</tt>
|
|
attribute.
|
|
Usage examples: <tt class="docutils literal">(switch_option "foo", (init true))</tt>; <tt class="docutils literal">(prefix_option
|
|
"bar", (init <span class="pre">"baz"))</span></tt>.</li>
|
|
</ul>
|
|
</blockquote>
|
|
</li>
|
|
</ul>
|
|
</div>
|
|
<div class="section" id="conditional-evaluation">
|
|
<span id="case"></span><h1><a class="toc-backref" href="#id13">Conditional evaluation</a></h1>
|
|
<p>The 'case' construct is the main means by which programmability is achieved in
|
|
LLVMC. It can be used to calculate edge weights, program actions and modify the
|
|
shell commands to be executed. The 'case' expression is designed after the
|
|
similarly-named construct in functional languages and takes the form <tt class="docutils literal">(case
|
|
(test_1), statement_1, (test_2), statement_2, ... (test_N), statement_N)</tt>. The
|
|
statements are evaluated only if the corresponding tests evaluate to true.</p>
|
|
<p>Examples:</p>
|
|
<pre class="literal-block">
|
|
// Edge weight calculation
|
|
|
|
// Increases edge weight by 5 if "-A" is provided on the
|
|
// command-line, and by 5 more if "-B" is also provided.
|
|
(case
|
|
(switch_on "A"), (inc_weight 5),
|
|
(switch_on "B"), (inc_weight 5))
|
|
|
|
|
|
// Tool command line specification
|
|
|
|
// Evaluates to "cmdline1" if the option "-A" is provided on the
|
|
// command line; to "cmdline2" if "-B" is provided;
|
|
// otherwise to "cmdline3".
|
|
|
|
(case
|
|
(switch_on "A"), "cmdline1",
|
|
(switch_on "B"), "cmdline2",
|
|
(default), "cmdline3")
|
|
</pre>
|
|
<p>Note the slight difference in 'case' expression handling in contexts of edge
|
|
weights and command line specification - in the second example the value of the
|
|
<tt class="docutils literal">"B"</tt> switch is never checked when switch <tt class="docutils literal">"A"</tt> is enabled, and the whole
|
|
expression always evaluates to <tt class="docutils literal">"cmdline1"</tt> in that case.</p>
|
|
<p>Case expressions can also be nested, i.e. the following is legal:</p>
|
|
<pre class="literal-block">
|
|
(case (switch_on "E"), (case (switch_on "o"), ..., (default), ...)
|
|
(default), ...)
|
|
</pre>
|
|
<p>You should, however, try to avoid doing that because it hurts readability. It is
|
|
usually better to split tool descriptions and/or use TableGen inheritance
|
|
instead.</p>
|
|
<ul class="simple">
|
|
<li>Possible tests are:<ul>
|
|
<li><tt class="docutils literal">switch_on</tt> - Returns true if a given command-line switch is provided by
|
|
the user. Can be given multiple arguments, in that case <tt class="docutils literal">(switch_on "foo",
|
|
"bar", "baz")</tt> is equivalent to <tt class="docutils literal">(and (switch_on <span class="pre">"foo"),</span> (switch_on
|
|
<span class="pre">"bar"),</span> (switch_on <span class="pre">"baz"))</span></tt>.
|
|
Example: <tt class="docutils literal">(switch_on "opt")</tt>.</li>
|
|
<li><tt class="docutils literal">any_switch_on</tt> - Given a number of switch options, returns true if any of
|
|
the switches is turned on.
|
|
Example: <tt class="docutils literal">(any_switch_on "foo", "bar", "baz")</tt> is equivalent to <tt class="docutils literal">(or
|
|
(switch_on <span class="pre">"foo"),</span> (switch_on <span class="pre">"bar"),</span> (switch_on <span class="pre">"baz"))</span></tt>.</li>
|
|
<li><tt class="docutils literal">parameter_equals</tt> - Returns true if a command-line parameter (first
|
|
argument) equals a given value (second argument).
|
|
Example: <tt class="docutils literal">(parameter_equals "W", "all")</tt>.</li>
|
|
<li><tt class="docutils literal">element_in_list</tt> - Returns true if a command-line parameter list (first
|
|
argument) contains a given value (second argument).
|
|
Example: <tt class="docutils literal">(element_in_list "l", "pthread")</tt>.</li>
|
|
<li><tt class="docutils literal">input_languages_contain</tt> - Returns true if a given language
|
|
belongs to the current input language set.
|
|
Example: <tt class="docutils literal">(input_languages_contain <span class="pre">"c++")</span></tt>.</li>
|
|
<li><tt class="docutils literal">in_language</tt> - Evaluates to true if the input file language is equal to
|
|
the argument. At the moment works only with <tt class="docutils literal">command</tt> and <tt class="docutils literal">actions</tt> (on
|
|
non-join nodes).
|
|
Example: <tt class="docutils literal">(in_language <span class="pre">"c++")</span></tt>.</li>
|
|
<li><tt class="docutils literal">not_empty</tt> - Returns true if a given option (which should be either a
|
|
parameter or a parameter list) is set by the user. Like <tt class="docutils literal">switch_on</tt>, can
|
|
be also given multiple arguments.
|
|
Examples: <tt class="docutils literal">(not_empty "o")</tt>, <tt class="docutils literal">(not_empty "o", "l")</tt>.</li>
|
|
<li><tt class="docutils literal">any_not_empty</tt> - Returns true if <tt class="docutils literal">not_empty</tt> returns true for any of
|
|
the provided options.
|
|
Example: <tt class="docutils literal">(any_not_empty "foo", "bar", "baz")</tt> is equivalent to <tt class="docutils literal">(or
|
|
(not_empty <span class="pre">"foo"),</span> (not_empty <span class="pre">"bar"),</span> (not_empty <span class="pre">"baz"))</span></tt>.</li>
|
|
<li><tt class="docutils literal">empty</tt> - The opposite of <tt class="docutils literal">not_empty</tt>. Equivalent to <tt class="docutils literal">(not (not_empty
|
|
X))</tt>. Can be given multiple arguments.</li>
|
|
<li><tt class="docutils literal">any_not_empty</tt> - Returns true if <tt class="docutils literal">not_empty</tt> returns true for any of
|
|
the provided options.
|
|
Example: <tt class="docutils literal">(any_empty "foo", "bar", "baz")</tt> is equivalent to <tt class="docutils literal">(or
|
|
(not_empty <span class="pre">"foo"),</span> (not_empty <span class="pre">"bar"),</span> (not_empty <span class="pre">"baz"))</span></tt>.</li>
|
|
<li><tt class="docutils literal">single_input_file</tt> - Returns true if there was only one input file
|
|
provided on the command-line. Used without arguments:
|
|
<tt class="docutils literal">(single_input_file)</tt>.</li>
|
|
<li><tt class="docutils literal">multiple_input_files</tt> - Equivalent to <tt class="docutils literal">(not (single_input_file))</tt> (the
|
|
case of zero input files is considered an error).</li>
|
|
<li><tt class="docutils literal">default</tt> - Always evaluates to true. Should always be the last
|
|
test in the <tt class="docutils literal">case</tt> expression.</li>
|
|
<li><tt class="docutils literal">and</tt> - A standard logical combinator that returns true iff all of
|
|
its arguments return true. Used like this: <tt class="docutils literal">(and (test1), (test2),
|
|
... (testN))</tt>. Nesting of <tt class="docutils literal">and</tt> and <tt class="docutils literal">or</tt> is allowed, but not
|
|
encouraged.</li>
|
|
<li><tt class="docutils literal">or</tt> - A logical combinator that returns true iff any of its arguments
|
|
return true.
|
|
Example: <tt class="docutils literal">(or (test1), (test2), ... (testN))</tt>.</li>
|
|
<li><tt class="docutils literal">not</tt> - Standard unary logical combinator that negates its
|
|
argument.
|
|
Example: <tt class="docutils literal">(not (or (test1), (test2), ... <span class="pre">(testN)))</span></tt>.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
</div>
|
|
<div class="section" id="writing-a-tool-description">
|
|
<h1><a class="toc-backref" href="#id14">Writing a tool description</a></h1>
|
|
<p>As was said earlier, nodes in the compilation graph represent tools, which are
|
|
described separately. A tool definition looks like this (taken from the
|
|
<tt class="docutils literal">llvmc/src/Base.td</tt> file):</p>
|
|
<pre class="literal-block">
|
|
def llvm_gcc_cpp : Tool<[
|
|
(in_language "c++"),
|
|
(out_language "llvm-assembler"),
|
|
(output_suffix "bc"),
|
|
(command "llvm-g++ -c -emit-llvm"),
|
|
(sink)
|
|
]>;
|
|
</pre>
|
|
<p>This defines a new tool called <tt class="docutils literal">llvm_gcc_cpp</tt>, which is an alias for
|
|
<tt class="docutils literal"><span class="pre">llvm-g++</span></tt>. As you can see, a tool definition is just a list of properties;
|
|
most of them should be self-explanatory. The <tt class="docutils literal">sink</tt> property means that this
|
|
tool should be passed all command-line options that aren't mentioned in the
|
|
option list.</p>
|
|
<p>The complete list of all currently implemented tool properties follows.</p>
|
|
<ul class="simple">
|
|
<li>Possible tool properties:<ul>
|
|
<li><tt class="docutils literal">in_language</tt> - input language name. Can be given multiple arguments, in
|
|
case the tool supports multiple input languages. Used for typechecking and
|
|
mapping file extensions to tools.</li>
|
|
<li><tt class="docutils literal">out_language</tt> - output language name. Multiple output languages are
|
|
allowed. Used for typechecking the compilation graph.</li>
|
|
<li><tt class="docutils literal">output_suffix</tt> - output file suffix. Can also be changed dynamically, see
|
|
documentation on <a class="reference internal" href="#actions">actions</a>.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<blockquote>
|
|
<ul class="simple">
|
|
<li><tt class="docutils literal">command</tt> - the actual command used to run the tool. You can use output
|
|
redirection with <tt class="docutils literal">></tt>, hook invocations (<tt class="docutils literal">$CALL</tt>), environment variables
|
|
(via <tt class="docutils literal">$ENV</tt>) and the <tt class="docutils literal">case</tt> construct.</li>
|
|
<li><tt class="docutils literal">join</tt> - this tool is a "join node" in the graph, i.e. it gets a list of
|
|
input files and joins them together. Used for linkers.</li>
|
|
<li><tt class="docutils literal">sink</tt> - all command-line options that are not handled by other tools are
|
|
passed to this tool.</li>
|
|
<li><tt class="docutils literal">actions</tt> - A single big <tt class="docutils literal">case</tt> expression that specifies how this tool
|
|
reacts on command-line options (described in more detail <a class="reference internal" href="#actions">below</a>).</li>
|
|
</ul>
|
|
</blockquote>
|
|
<blockquote>
|
|
<ul class="simple">
|
|
<li><tt class="docutils literal">out_file_option</tt>, <tt class="docutils literal">in_file_option</tt> - Options appended to the
|
|
<tt class="docutils literal">command</tt> string to designate output and input files. Default values are
|
|
<tt class="docutils literal"><span class="pre">"-o"</span></tt> and <tt class="docutils literal">""</tt>, respectively.</li>
|
|
</ul>
|
|
</blockquote>
|
|
<div class="section" id="id4">
|
|
<span id="actions"></span><h2><a class="toc-backref" href="#id15">Actions</a></h2>
|
|
<p>A tool often needs to react to command-line options, and this is precisely what
|
|
the <tt class="docutils literal">actions</tt> property is for. The next example illustrates this feature:</p>
|
|
<pre class="literal-block">
|
|
def llvm_gcc_linker : Tool<[
|
|
(in_language "object-code"),
|
|
(out_language "executable"),
|
|
(output_suffix "out"),
|
|
(command "llvm-gcc"),
|
|
(join),
|
|
(actions (case (not_empty "L"), (forward "L"),
|
|
(not_empty "l"), (forward "l"),
|
|
(not_empty "dummy"),
|
|
[(append_cmd "-dummy1"), (append_cmd "-dummy2")])
|
|
]>;
|
|
</pre>
|
|
<p>The <tt class="docutils literal">actions</tt> tool property is implemented on top of the omnipresent <tt class="docutils literal">case</tt>
|
|
expression. It associates one or more different <em>actions</em> with given
|
|
conditions - in the example, the actions are <tt class="docutils literal">forward</tt>, which forwards a given
|
|
option unchanged, and <tt class="docutils literal">append_cmd</tt>, which appends a given string to the tool
|
|
execution command. Multiple actions can be associated with a single condition by
|
|
using a list of actions (used in the example to append some dummy options). The
|
|
same <tt class="docutils literal">case</tt> construct can also be used in the <tt class="docutils literal">cmd_line</tt> property to modify
|
|
the tool command line.</p>
|
|
<p>The "join" property used in the example means that this tool behaves like a
|
|
linker.</p>
|
|
<p>The list of all possible actions follows.</p>
|
|
<ul>
|
|
<li><p class="first">Possible actions:</p>
|
|
<blockquote>
|
|
<ul class="simple">
|
|
<li><tt class="docutils literal">append_cmd</tt> - Append a string to the tool invocation command.
|
|
Example: <tt class="docutils literal">(case (switch_on <span class="pre">"pthread"),</span> (append_cmd <span class="pre">"-lpthread"))</span></tt>.</li>
|
|
<li><tt class="docutils literal">error</tt> - Exit with error.
|
|
Example: <tt class="docutils literal">(error "Mixing <span class="pre">-c</span> and <span class="pre">-S</span> is not <span class="pre">allowed!")</span></tt>.</li>
|
|
<li><tt class="docutils literal">warning</tt> - Print a warning.
|
|
Example: <tt class="docutils literal">(warning "Specifying both <span class="pre">-O1</span> and <span class="pre">-O2</span> is <span class="pre">meaningless!")</span></tt>.</li>
|
|
<li><tt class="docutils literal">forward</tt> - Forward the option unchanged.
|
|
Example: <tt class="docutils literal">(forward "Wall")</tt>.</li>
|
|
<li><tt class="docutils literal">forward_as</tt> - Change the option's name, but forward the argument
|
|
unchanged.
|
|
Example: <tt class="docutils literal">(forward_as "O0", <span class="pre">"--disable-optimization")</span></tt>.</li>
|
|
<li><tt class="docutils literal">forward_value</tt> - Forward only option's value. Cannot be used with switch
|
|
options (since they don't have values), but works fine with lists.
|
|
Example: <tt class="docutils literal">(forward_value <span class="pre">"Wa,")</span></tt>.</li>
|
|
<li><tt class="docutils literal">forward_transformed_value</tt> - As above, but applies a hook to the
|
|
option's value before forwarding (see <a class="reference internal" href="#hooks">below</a>). When
|
|
<tt class="docutils literal">forward_transformed_value</tt> is applied to a list
|
|
option, the hook must have signature
|
|
<tt class="docutils literal"><span class="pre">std::string</span> <span class="pre">hooks::HookName</span> (const <span class="pre">std::vector<std::string>&)</span></tt>.
|
|
Example: <tt class="docutils literal">(forward_transformed_value "m", "ConvertToMAttr")</tt>.</li>
|
|
<li><tt class="docutils literal">output_suffix</tt> - Modify the output suffix of this tool.
|
|
Example: <tt class="docutils literal">(output_suffix "i")</tt>.</li>
|
|
<li><tt class="docutils literal">stop_compilation</tt> - Stop compilation after this tool processes its
|
|
input. Used without arguments.
|
|
Example: <tt class="docutils literal">(stop_compilation)</tt>.</li>
|
|
</ul>
|
|
</blockquote>
|
|
</li>
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="language-map">
|
|
<h1><a class="toc-backref" href="#id16">Language map</a></h1>
|
|
<p>If you are adding support for a new language to LLVMC, you'll need to modify the
|
|
language map, which defines mappings from file extensions to language names. It
|
|
is used to choose the proper toolchain(s) for a given input file set. Language
|
|
map definition looks like this:</p>
|
|
<pre class="literal-block">
|
|
def LanguageMap : LanguageMap<
|
|
[LangToSuffixes<"c++", ["cc", "cp", "cxx", "cpp", "CPP", "c++", "C"]>,
|
|
LangToSuffixes<"c", ["c"]>,
|
|
...
|
|
]>;
|
|
</pre>
|
|
<p>For example, without those definitions the following command wouldn't work:</p>
|
|
<pre class="literal-block">
|
|
$ llvmc hello.cpp
|
|
llvmc: Unknown suffix: cpp
|
|
</pre>
|
|
<p>The language map entries are needed only for the tools that are linked from the
|
|
root node. A tool can have multiple output languages.</p>
|
|
</div>
|
|
<div class="section" id="option-preprocessor">
|
|
<h1><a class="toc-backref" href="#id17">Option preprocessor</a></h1>
|
|
<p>It is sometimes useful to run error-checking code before processing the
|
|
compilation graph. For example, if optimization options "-O1" and "-O2" are
|
|
implemented as switches, we might want to output a warning if the user invokes
|
|
the driver with both of these options enabled.</p>
|
|
<p>The <tt class="docutils literal">OptionPreprocessor</tt> feature is reserved specially for these
|
|
occasions. Example (adapted from <tt class="docutils literal">llvm/src/Base.td.in</tt>):</p>
|
|
<pre class="literal-block">
|
|
def Preprocess : OptionPreprocessor<
|
|
(case (not (any_switch_on "O0", "O1", "O2", "O3")),
|
|
(set_option "O2"),
|
|
(and (switch_on "O3"), (any_switch_on "O0", "O1", "O2")),
|
|
(unset_option "O0", "O1", "O2"),
|
|
(and (switch_on "O2"), (any_switch_on "O0", "O1")),
|
|
(unset_option "O0", "O1"),
|
|
(and (switch_on "O1"), (switch_on "O0")),
|
|
(unset_option "O0"))
|
|
>;
|
|
</pre>
|
|
<p>Here, <tt class="docutils literal">OptionPreprocessor</tt> is used to unset all spurious <tt class="docutils literal"><span class="pre">-O</span></tt> options so
|
|
that they are not forwarded to the compiler. If no optimization options are
|
|
specified, <tt class="docutils literal"><span class="pre">-O2</span></tt> is enabled.</p>
|
|
<p><tt class="docutils literal">OptionPreprocessor</tt> is basically a single big <tt class="docutils literal">case</tt> expression, which is
|
|
evaluated only once right after the driver is started. The only allowed actions
|
|
in <tt class="docutils literal">OptionPreprocessor</tt> are <tt class="docutils literal">error</tt>, <tt class="docutils literal">warning</tt>, and two special actions:
|
|
<tt class="docutils literal">unset_option</tt> and <tt class="docutils literal">set_option</tt>. As their names suggest, they can be used to
|
|
set or unset a given option. To set an option with <tt class="docutils literal">set_option</tt>, use the
|
|
two-argument form: <tt class="docutils literal">(set_option "parameter", VALUE)</tt>. Here, <tt class="docutils literal">VALUE</tt> can be
|
|
either a string, a string list, or a boolean constant.</p>
|
|
<p>For convenience, <tt class="docutils literal">set_option</tt> and <tt class="docutils literal">unset_option</tt> also work with multiple
|
|
arguments. That is, instead of <tt class="docutils literal">[(unset_option <span class="pre">"A"),</span> (unset_option <span class="pre">"B")]</span></tt> you
|
|
can use <tt class="docutils literal">(unset_option "A", "B")</tt>. Obviously, <tt class="docutils literal">(set_option "A", "B")</tt> is
|
|
only valid if both <tt class="docutils literal">A</tt> and <tt class="docutils literal">B</tt> are switches.</p>
|
|
</div>
|
|
<div class="section" id="more-advanced-topics">
|
|
<h1><a class="toc-backref" href="#id18">More advanced topics</a></h1>
|
|
<div class="section" id="hooks-and-environment-variables">
|
|
<span id="hooks"></span><h2><a class="toc-backref" href="#id19">Hooks and environment variables</a></h2>
|
|
<p>Normally, LLVMC searches for programs in the system <tt class="docutils literal">PATH</tt>. Sometimes, this is
|
|
not sufficient: for example, we may want to specify tool paths or names in the
|
|
configuration file. This can be achieved via the hooks mechanism. To write your
|
|
own hooks, add their definitions to the <tt class="docutils literal">Hooks.cpp</tt> or drop a <tt class="docutils literal">.cpp</tt> file
|
|
into your driver directory. Hooks should live in the <tt class="docutils literal">hooks</tt> namespace and
|
|
have the signature <tt class="docutils literal"><span class="pre">std::string</span> <span class="pre">hooks::MyHookName</span> ([const char* Arg0 [ const
|
|
char* Arg2 [, <span class="pre">...]]])</span></tt>. They can be used from the <tt class="docutils literal">command</tt> tool property:</p>
|
|
<pre class="literal-block">
|
|
(command "$CALL(MyHook)/path/to/file -o $CALL(AnotherHook)")
|
|
</pre>
|
|
<p>To pass arguments to hooks, use the following syntax:</p>
|
|
<pre class="literal-block">
|
|
(command "$CALL(MyHook, 'Arg1', 'Arg2', 'Arg # 3')/path/to/file -o1 -o2")
|
|
</pre>
|
|
<p>It is also possible to use environment variables in the same manner:</p>
|
|
<pre class="literal-block">
|
|
(command "$ENV(VAR1)/path/to/file -o $ENV(VAR2)")
|
|
</pre>
|
|
<p>To change the command line string based on user-provided options use
|
|
the <tt class="docutils literal">case</tt> expression (documented <a class="reference internal" href="#case">above</a>):</p>
|
|
<pre class="literal-block">
|
|
(command
|
|
(case
|
|
(switch_on "E"),
|
|
"llvm-g++ -E -x c $INFILE -o $OUTFILE",
|
|
(default),
|
|
"llvm-g++ -c -x c $INFILE -o $OUTFILE -emit-llvm"))
|
|
</pre>
|
|
</div>
|
|
<div class="section" id="debugging">
|
|
<h2><a class="toc-backref" href="#id20">Debugging</a></h2>
|
|
<p>When writing LLVMC-based drivers, it can be useful to get a visual view of the
|
|
resulting compilation graph. This can be achieved via the command line option
|
|
<tt class="docutils literal"><span class="pre">--view-graph</span></tt> (which assumes that <a class="reference external" href="http://www.graphviz.org/">Graphviz</a> and <a class="reference external" href="http://pages.cs.wisc.edu/~ghost/">Ghostview</a> are
|
|
installed). There is also a <tt class="docutils literal"><span class="pre">--write-graph</span></tt> option that creates a Graphviz
|
|
source file (<tt class="docutils literal"><span class="pre">compilation-graph.dot</span></tt>) in the current directory.</p>
|
|
<p>Another useful <tt class="docutils literal">llvmc</tt> option is <tt class="docutils literal"><span class="pre">--check-graph</span></tt>. It checks the compilation
|
|
graph for common errors like mismatched output/input language names, multiple
|
|
default edges and cycles. When invoked with <tt class="docutils literal"><span class="pre">--check-graph</span></tt>, <tt class="docutils literal">llvmc</tt> doesn't
|
|
perform any compilation tasks and returns the number of encountered errors as
|
|
its status code. In the future, these checks will be performed at compile-time
|
|
and this option will disappear.</p>
|
|
</div>
|
|
<div class="section" id="conditioning-on-the-executable-name">
|
|
<h2><a class="toc-backref" href="#id21">Conditioning on the executable name</a></h2>
|
|
<p>For now, the executable name (the value passed to the driver in <tt class="docutils literal">argv[0]</tt>) is
|
|
accessible only in the C++ code (i.e. hooks). Use the following code:</p>
|
|
<pre class="literal-block">
|
|
namespace llvmc {
|
|
extern const char* ProgramName;
|
|
}
|
|
|
|
namespace hooks {
|
|
|
|
std::string MyHook() {
|
|
//...
|
|
if (strcmp(ProgramName, "mydriver") == 0) {
|
|
//...
|
|
|
|
}
|
|
|
|
} // end namespace hooks
|
|
</pre>
|
|
<p>In general, you're encouraged not to make the behaviour dependent on the
|
|
executable file name, and use command-line switches instead. See for example how
|
|
the <tt class="docutils literal">llvmc</tt> program behaves when it needs to choose the correct linker options
|
|
(think <tt class="docutils literal">g++</tt> vs. <tt class="docutils literal">gcc</tt>).</p>
|
|
<hr />
|
|
<address>
|
|
<a href="http://jigsaw.w3.org/css-validator/check/referer">
|
|
<img src="http://jigsaw.w3.org/css-validator/images/vcss-blue"
|
|
alt="Valid CSS" /></a>
|
|
<a href="http://validator.w3.org/check?uri=referer">
|
|
<img src="http://www.w3.org/Icons/valid-xhtml10-blue"
|
|
alt="Valid XHTML 1.0 Transitional"/></a>
|
|
|
|
<a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a><br />
|
|
<a href="http://llvm.org">LLVM Compiler Infrastructure</a><br />
|
|
|
|
Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $
|
|
</address></div>
|
|
</div>
|
|
</div>
|
|
</body>
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</html>
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