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-<title>Customizing LLVMC: Reference Manual</title>
-<meta name="author" content="Mikhail Glushenkov <foldr@codedegers.com>" />
-<link rel="stylesheet" href="llvm-rst.css" type="text/css" />
+<meta name="generator" content="Docutils 0.5: http://docutils.sourceforge.net/" />
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<body>
-<div class="document" id="customizing-llvmc-reference-manual">
-<h1 class="title">Customizing LLVMC: Reference Manual</h1>
-<table class="docinfo" frame="void" rules="none">
-<col class="docinfo-name" />
-<col class="docinfo-content" />
-<tbody valign="top">
-<tr><th class="docinfo-name">Author:</th>
-<td>Mikhail Glushenkov <<a class="reference" href="mailto:foldr@codedegers.com">foldr@codedegers.com</a>></td></tr>
-</tbody>
-</table>
-<p>LLVMC is a generic compiler driver, designed to be customizable and
-extensible. It plays the same role for LLVM as the <tt class="docutils literal"><span class="pre">gcc</span></tt> program
-does for GCC - LLVMC's job is essentially to transform a set of input
-files into a set of targets depending on configuration rules and user
-options. What makes LLVMC different is that these transformation rules
-are completely customizable - in fact, LLVMC knows nothing about the
-specifics of transformation (even the command-line options are mostly
-not hard-coded) and regards the transformation structure as an
-abstract graph. The structure of this graph is completely determined
-by plugins, which can be either statically or dynamically linked. This
-makes it possible to easily adapt LLVMC for other purposes - for
-example, as a build tool for game resources.</p>
-<p>Because LLVMC employs TableGen <a class="footnote-reference" href="#id7" id="id1" name="id1">[1]</a> as its configuration language, you
-need to be familiar with it to customize LLVMC.</p>
-<div class="contents topic">
-<p class="topic-title first"><a id="contents" name="contents">Contents</a></p>
+<div class="document" id="tutorial-using-llvmc">
+<h1 class="title">Tutorial - Using LLVMC</h1>
+
+<!-- This file was automatically generated by rst2html.
+Please do not edit directly!
+The ReST source lives in the directory 'tools/llvmc/doc'. -->
+<div class="contents topic" id="contents">
+<p class="topic-title first">Contents</p>
<ul class="simple">
-<li><a class="reference" href="#compiling-with-llvmc" id="id10" name="id10">Compiling with LLVMC</a></li>
-<li><a class="reference" href="#predefined-options" id="id11" name="id11">Predefined options</a></li>
-<li><a class="reference" href="#compiling-llvmc-plugins" id="id12" name="id12">Compiling LLVMC plugins</a></li>
-<li><a class="reference" href="#customizing-llvmc-the-compilation-graph" id="id13" name="id13">Customizing LLVMC: the compilation graph</a></li>
-<li><a class="reference" href="#describing-options" id="id14" name="id14">Describing options</a><ul>
-<li><a class="reference" href="#external-options" id="id15" name="id15">External options</a></li>
-</ul>
-</li>
-<li><a class="reference" href="#conditional-evaluation" id="id16" name="id16">Conditional evaluation</a></li>
-<li><a class="reference" href="#writing-a-tool-description" id="id17" name="id17">Writing a tool description</a><ul>
-<li><a class="reference" href="#actions" id="id18" name="id18">Actions</a></li>
-</ul>
-</li>
-<li><a class="reference" href="#language-map" id="id19" name="id19">Language map</a></li>
-<li><a class="reference" href="#more-advanced-topics" id="id20" name="id20">More advanced topics</a><ul>
-<li><a class="reference" href="#hooks-and-environment-variables" id="id21" name="id21">Hooks and environment variables</a></li>
-<li><a class="reference" href="#how-plugins-are-loaded" id="id22" name="id22">How plugins are loaded</a></li>
-<li><a class="reference" href="#debugging" id="id23" name="id23">Debugging</a></li>
-</ul>
-</li>
-<li><a class="reference" href="#references" id="id24" name="id24">References</a></li>
+<li><a class="reference internal" href="#introduction" id="id1">Introduction</a></li>
+<li><a class="reference internal" href="#compiling-with-llvmc" id="id2">Compiling with LLVMC</a></li>
+<li><a class="reference internal" href="#using-llvmc-to-generate-toolchain-drivers" id="id3">Using LLVMC to generate toolchain drivers</a></li>
</ul>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id10" id="compiling-with-llvmc" name="compiling-with-llvmc">Compiling with LLVMC</a></h1>
-<p>LLVMC tries hard to be as compatible with <tt class="docutils literal"><span class="pre">gcc</span></tt> as possible,
-although there are some small differences. Most of the time, however,
-you shouldn't be able to notice them:</p>
+<div class="doc_author">
+<p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p>
+</div><div class="section" id="introduction">
+<h1><a class="toc-backref" href="#id1">Introduction</a></h1>
+<p>LLVMC is a generic compiler driver, which plays the same role for LLVM
+as the <tt class="docutils literal"><span class="pre">gcc</span></tt> program does for GCC - the difference being that LLVMC
+is designed to be more adaptable and easier to customize. Most of
+LLVMC functionality is implemented via plugins, which can be loaded
+dynamically or compiled in. This tutorial describes the basic usage
+and configuration of LLVMC.</p>
+</div>
+<div class="section" id="compiling-with-llvmc">
+<h1><a class="toc-backref" href="#id2">Compiling with LLVMC</a></h1>
+<p>In general, LLVMC tries to be command-line compatible with <tt class="docutils literal"><span class="pre">gcc</span></tt> as
+much as possible, so most of the familiar options work:</p>
<pre class="literal-block">
-$ # This works as expected:
$ llvmc -O3 -Wall hello.cpp
$ ./a.out
hello
</pre>
-<p>One nice feature of LLVMC is that one doesn't have to distinguish
-between different compilers for different languages (think <tt class="docutils literal"><span class="pre">g++</span></tt> and
-<tt class="docutils literal"><span class="pre">gcc</span></tt>) - the right toolchain is chosen automatically based on input
-language names (which are, in turn, determined from file
-extensions). If you want to force files ending with ".c" to compile as
-C++, use the <tt class="docutils literal"><span class="pre">-x</span></tt> option, just like you would do it with <tt class="docutils literal"><span class="pre">gcc</span></tt>:</p>
-<pre class="literal-block">
-$ # hello.c is really a C++ file
-$ llvmc -x c++ hello.c
-$ ./a.out
-hello
-</pre>
-<p>On the other hand, when using LLVMC as a linker to combine several C++
-object files you should provide the <tt class="docutils literal"><span class="pre">--linker</span></tt> option since it's
-impossible for LLVMC to choose the right linker in that case:</p>
-<pre class="literal-block">
-$ llvmc -c hello.cpp
-$ llvmc hello.o
-[A lot of link-time errors skipped]
-$ llvmc --linker=c++ hello.o
-$ ./a.out
-hello
-</pre>
-<p>By default, LLVMC uses <tt class="docutils literal"><span class="pre">llvm-gcc</span></tt> to compile the source code. It is
-also possible to choose the work-in-progress <tt class="docutils literal"><span class="pre">clang</span></tt> compiler with
-the <tt class="docutils literal"><span class="pre">-clang</span></tt> option.</p>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id11" id="predefined-options" name="predefined-options">Predefined options</a></h1>
-<p>LLVMC has some built-in options that can't be overridden in the
-configuration libraries:</p>
-<ul class="simple">
-<li><tt class="docutils literal"><span class="pre">-o</span> <span class="pre">FILE</span></tt> - Output file name.</li>
-<li><tt class="docutils literal"><span class="pre">-x</span> <span class="pre">LANGUAGE</span></tt> - Specify the language of the following input files
-until the next -x option.</li>
-<li><tt class="docutils literal"><span class="pre">-load</span> <span class="pre">PLUGIN_NAME</span></tt> - Load the specified plugin DLL. Example:
-<tt class="docutils literal"><span class="pre">-load</span> <span class="pre">$LLVM_DIR/Release/lib/LLVMCSimple.so</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">-v</span></tt> - Enable verbose mode, i.e. print out all executed commands.</li>
-<li><tt class="docutils literal"><span class="pre">--view-graph</span></tt> - Show a graphical representation of the compilation
-graph. Requires that you have <tt class="docutils literal"><span class="pre">dot</span></tt> and <tt class="docutils literal"><span class="pre">gv</span></tt> programs
-installed. Hidden option, useful for debugging.</li>
-<li><tt class="docutils literal"><span class="pre">--write-graph</span></tt> - Write a <tt class="docutils literal"><span class="pre">compilation-graph.dot</span></tt> file in the
-current directory with the compilation graph description in the
-Graphviz format. Hidden option, useful for debugging.</li>
-<li><tt class="docutils literal"><span class="pre">--save-temps</span></tt> - Write temporary files to the current directory
-and do not delete them on exit. Hidden option, useful for debugging.</li>
-<li><tt class="docutils literal"><span class="pre">--help</span></tt>, <tt class="docutils literal"><span class="pre">--help-hidden</span></tt>, <tt class="docutils literal"><span class="pre">--version</span></tt> - These options have
-their standard meaning.</li>
-</ul>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id12" id="compiling-llvmc-plugins" name="compiling-llvmc-plugins">Compiling LLVMC plugins</a></h1>
-<p>It's easiest to start working on your own LLVMC plugin by copying the
-skeleton project which lives under <tt class="docutils literal"><span class="pre">$LLVMC_DIR/plugins/Simple</span></tt>:</p>
-<pre class="literal-block">
-$ cd $LLVMC_DIR/plugins
-$ cp -r Simple MyPlugin
-$ cd MyPlugin
-$ ls
-Makefile PluginMain.cpp Simple.td
-</pre>
-<p>As you can see, our basic plugin consists of only two files (not
-counting the build script). <tt class="docutils literal"><span class="pre">Simple.td</span></tt> contains TableGen
-description of the compilation graph; its format is documented in the
-following sections. <tt class="docutils literal"><span class="pre">PluginMain.cpp</span></tt> is just a helper file used to
-compile the auto-generated C++ code produced from TableGen source. It
-can also contain hook definitions (see <a class="reference" href="#hooks">below</a>).</p>
-<p>The first thing that you should do is to change the <tt class="docutils literal"><span class="pre">LLVMC_PLUGIN</span></tt>
-variable in the <tt class="docutils literal"><span class="pre">Makefile</span></tt> to avoid conflicts (since this variable
-is used to name the resulting library):</p>
-<pre class="literal-block">
-LLVMC_PLUGIN=MyPlugin
-</pre>
-<p>It is also a good idea to rename <tt class="docutils literal"><span class="pre">Simple.td</span></tt> to something less
-generic:</p>
-<pre class="literal-block">
-$ mv Simple.td MyPlugin.td
-</pre>
-<p>Note that the plugin source directory must be placed under
-<tt class="docutils literal"><span class="pre">$LLVMC_DIR/plugins</span></tt> to make use of the existing build
-infrastructure. To build a version of the LLVMC executable called
-<tt class="docutils literal"><span class="pre">mydriver</span></tt> with your plugin compiled in, use the following command:</p>
-<pre class="literal-block">
-$ cd $LLVMC_DIR
-$ make BUILTIN_PLUGINS=MyPlugin DRIVER_NAME=mydriver
-</pre>
-<p>To build your plugin as a dynamic library, just <tt class="docutils literal"><span class="pre">cd</span></tt> to its source
-directory and run <tt class="docutils literal"><span class="pre">make</span></tt>. The resulting file will be called
-<tt class="docutils literal"><span class="pre">LLVMC$(LLVMC_PLUGIN).$(DLL_EXTENSION)</span></tt> (in our case,
-<tt class="docutils literal"><span class="pre">LLVMCMyPlugin.so</span></tt>). This library can be then loaded in with the
-<tt class="docutils literal"><span class="pre">-load</span></tt> option. Example:</p>
-<pre class="literal-block">
-$ cd $LLVMC_DIR/plugins/Simple
-$ make
-$ llvmc -load $LLVM_DIR/Release/lib/LLVMCSimple.so
-</pre>
-<p>Sometimes, you will want a 'bare-bones' version of LLVMC that has no
-built-in plugins. It can be compiled with the following command:</p>
-<pre class="literal-block">
-$ cd $LLVMC_DIR
-$ make BUILTIN_PLUGINS=""
-</pre>
+<p>This will invoke <tt class="docutils literal"><span class="pre">llvm-g++</span></tt> under the hood (you can see which
+commands are executed by using the <tt class="docutils literal"><span class="pre">-v</span></tt> option). For further help on
+command-line LLVMC usage, refer to the <tt class="docutils literal"><span class="pre">llvmc</span> <span class="pre">--help</span></tt> output.</p>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id13" id="customizing-llvmc-the-compilation-graph" name="customizing-llvmc-the-compilation-graph">Customizing LLVMC: the compilation graph</a></h1>
-<p>Each TableGen configuration file should include the common
-definitions:</p>
+<div class="section" id="using-llvmc-to-generate-toolchain-drivers">
+<h1><a class="toc-backref" href="#id3">Using LLVMC to generate toolchain drivers</a></h1>
+<p>LLVMC plugins are written mostly using <a class="reference external" href="http://llvm.org/docs/TableGenFundamentals.html">TableGen</a>, so you need to
+be familiar with it to get anything done.</p>
+<p>Start by compiling <tt class="docutils literal"><span class="pre">example/Simple</span></tt>, which is a primitive wrapper for
+<tt class="docutils literal"><span class="pre">gcc</span></tt>:</p>
<pre class="literal-block">
-include "llvm/CompilerDriver/Common.td"
-</pre>
-<p>Internally, LLVMC stores information about possible source
-transformations in form of a graph. Nodes in this graph represent
-tools, and edges between two nodes represent a transformation path. A
-special "root" node is used to mark entry points for the
-transformations. LLVMC also assigns a weight to each edge (more on
-this later) to choose between several alternative edges.</p>
-<p>The definition of the compilation graph (see file
-<tt class="docutils literal"><span class="pre">plugins/Base/Base.td</span></tt> for an example) is just a list of edges:</p>
-<pre class="literal-block">
-def CompilationGraph : CompilationGraph<[
- Edge<"root", "llvm_gcc_c">,
- Edge<"root", "llvm_gcc_assembler">,
- ...
+$ cd $LLVM_DIR/tools/llvmc
+$ cp -r example/Simple plugins/Simple
- Edge<"llvm_gcc_c", "llc">,
- Edge<"llvm_gcc_cpp", "llc">,
- ...
+ # NB: A less verbose way to compile standalone LLVMC-based drivers is
+ # described in the reference manual.
- OptionalEdge<"llvm_gcc_c", "opt", (case (switch_on "opt"),
- (inc_weight))>,
- OptionalEdge<"llvm_gcc_cpp", "opt", (case (switch_on "opt"),
- (inc_weight))>,
- ...
-
- OptionalEdge<"llvm_gcc_assembler", "llvm_gcc_cpp_linker",
- (case (input_languages_contain "c++"), (inc_weight),
- (or (parameter_equals "linker", "g++"),
- (parameter_equals "linker", "c++")), (inc_weight))>,
- ...
+$ make LLVMC_BASED_DRIVER_NAME=mygcc LLVMC_BUILTIN_PLUGINS=Simple
+$ cat > hello.c
+[...]
+$ mygcc hello.c
+$ ./hello.out
+Hello
+</pre>
+<p>Here we link our plugin with the LLVMC core statically to form an executable
+file called <tt class="docutils literal"><span class="pre">mygcc</span></tt>. It is also possible to build our plugin as a dynamic
+library to be loaded by the <tt class="docutils literal"><span class="pre">llvmc</span></tt> executable (or any other LLVMC-based
+standalone driver); this is described in the reference manual.</p>
+<p>Contents of the file <tt class="docutils literal"><span class="pre">Simple.td</span></tt> look like this:</p>
+<pre class="literal-block">
+// Include common definitions
+include "llvm/CompilerDriver/Common.td"
- ]>;
-</pre>
-<p>As you can see, the edges can be either default or optional, where
-optional edges are differentiated by an additional <tt class="docutils literal"><span class="pre">case</span></tt> expression
-used to calculate the weight of this edge. Notice also that we refer
-to tools via their names (as strings). This makes it possible to add
-edges to an existing compilation graph in plugins without having to
-know about all tool definitions used in the graph.</p>
-<p>The default edges are assigned a weight of 1, and optional edges get a
-weight of 0 + 2*N where N is the number of tests that evaluated to
-true in the <tt class="docutils literal"><span class="pre">case</span></tt> expression. It is also possible to provide an
-integer parameter to <tt class="docutils literal"><span class="pre">inc_weight</span></tt> and <tt class="docutils literal"><span class="pre">dec_weight</span></tt> - in this case,
-the weight is increased (or decreased) by the provided value instead
-of the default 2. It is also possible to change the default weight of
-an optional edge by using the <tt class="docutils literal"><span class="pre">default</span></tt> clause of the <tt class="docutils literal"><span class="pre">case</span></tt>
-construct.</p>
-<p>When passing an input file through the graph, LLVMC picks the edge
-with the maximum weight. To avoid ambiguity, there should be only one
-default edge between two nodes (with the exception of the root node,
-which gets a special treatment - there you are allowed to specify one
-default edge <em>per language</em>).</p>
-<p>When multiple plugins are loaded, their compilation graphs are merged
-together. Since multiple edges that have the same end nodes are not
-allowed (i.e. the graph is not a multigraph), an edge defined in
-several plugins will be replaced by the definition from the plugin
-that was loaded last. Plugin load order can be controlled by using the
-plugin priority feature described above.</p>
-<p>To get a visual representation of the compilation graph (useful for
-debugging), run <tt class="docutils literal"><span class="pre">llvmc</span> <span class="pre">--view-graph</span></tt>. You will need <tt class="docutils literal"><span class="pre">dot</span></tt> and
-<tt class="docutils literal"><span class="pre">gsview</span></tt> installed for this to work properly.</p>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id14" id="describing-options" name="describing-options">Describing options</a></h1>
-<p>Command-line options that the plugin supports are defined by using an
-<tt class="docutils literal"><span class="pre">OptionList</span></tt>:</p>
-<pre class="literal-block">
-def Options : OptionList<[
-(switch_option "E", (help "Help string")),
-(alias_option "quiet", "q")
-...
+// Tool descriptions
+def gcc : Tool<
+[(in_language "c"),
+ (out_language "executable"),
+ (output_suffix "out"),
+ (cmd_line "gcc $INFILE -o $OUTFILE"),
+ (sink)
]>;
-</pre>
-<p>As you can see, the option list is just a list of DAGs, where each DAG
-is an option description consisting of the option name and some
-properties. A plugin can define more than one option list (they are
-all merged together in the end), which can be handy if one wants to
-separate option groups syntactically.</p>
-<ul>
-<li><p class="first">Possible option types:</p>
-<blockquote>
-<ul class="simple">
-<li><tt class="docutils literal"><span class="pre">switch_option</span></tt> - a simple boolean switch, for example <tt class="docutils literal"><span class="pre">-time</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">parameter_option</span></tt> - option that takes an argument, for example
-<tt class="docutils literal"><span class="pre">-std=c99</span></tt>;</li>
-<li><tt class="docutils literal"><span class="pre">parameter_list_option</span></tt> - same as the above, but more than one
-occurence of the option is allowed.</li>
-<li><tt class="docutils literal"><span class="pre">prefix_option</span></tt> - same as the parameter_option, but the option name
-and parameter value are not separated.</li>
-<li><tt class="docutils literal"><span class="pre">prefix_list_option</span></tt> - same as the above, but more than one
-occurence of the option is allowed; example: <tt class="docutils literal"><span class="pre">-lm</span> <span class="pre">-lpthread</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">alias_option</span></tt> - a special option type for creating
-aliases. Unlike other option types, aliases are not allowed to
-have any properties besides the aliased option name. Usage
-example: <tt class="docutils literal"><span class="pre">(alias_option</span> <span class="pre">"preprocess",</span> <span class="pre">"E")</span></tt></li>
-</ul>
-</blockquote>
-</li>
-<li><p class="first">Possible option properties:</p>
-<blockquote>
-<ul class="simple">
-<li><tt class="docutils literal"><span class="pre">help</span></tt> - help string associated with this option. Used for
-<tt class="docutils literal"><span class="pre">--help</span></tt> output.</li>
-<li><tt class="docutils literal"><span class="pre">required</span></tt> - this option is obligatory.</li>
-<li><tt class="docutils literal"><span class="pre">hidden</span></tt> - this option should not appear in the <tt class="docutils literal"><span class="pre">--help</span></tt>
-output (but should appear in the <tt class="docutils literal"><span class="pre">--help-hidden</span></tt> output).</li>
-<li><tt class="docutils literal"><span class="pre">really_hidden</span></tt> - the option should not appear in any help
-output.</li>
-<li><tt class="docutils literal"><span class="pre">extern</span></tt> - this option is defined in some other plugin, see below.</li>
-</ul>
-</blockquote>
-</li>
-</ul>
-<div class="section">
-<h2><a class="toc-backref" href="#id15" id="external-options" name="external-options">External options</a></h2>
-<p>Sometimes, when linking several plugins together, one plugin needs to
-access options defined in some other plugin. Because of the way
-options are implemented, such options should be marked as
-<tt class="docutils literal"><span class="pre">extern</span></tt>. This is what the <tt class="docutils literal"><span class="pre">extern</span></tt> option property is
-for. Example:</p>
-<pre class="literal-block">
-...
-(switch_option "E", (extern))
-...
-</pre>
-<p>See also the section on plugin <a class="reference" href="#priorities">priorities</a>.</p>
-</div>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id16" id="conditional-evaluation" name="conditional-evaluation"><span id="case"></span>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"><span class="pre">(case</span> <span class="pre">(test_1),</span> <span class="pre">statement_1,</span>
-<span class="pre">(test_2),</span> <span class="pre">statement_2,</span> <span class="pre">...</span> <span class="pre">(test_N),</span> <span class="pre">statement_N)</span></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".
+// Language map
+def LanguageMap : LanguageMap<[LangToSuffixes<"c", ["c"]>]>;
-(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"><span class="pre">"B"</span></tt> switch is never checked when switch <tt class="docutils literal"><span class="pre">"A"</span></tt> is
-enabled, and the whole expression always evaluates to <tt class="docutils literal"><span class="pre">"cmdline1"</span></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"><span class="pre">switch_on</span></tt> - Returns true if a given command-line switch is
-provided by the user. Example: <tt class="docutils literal"><span class="pre">(switch_on</span> <span class="pre">"opt")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">parameter_equals</span></tt> - Returns true if a command-line parameter equals
-a given value.
-Example: <tt class="docutils literal"><span class="pre">(parameter_equals</span> <span class="pre">"W",</span> <span class="pre">"all")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">element_in_list</span></tt> - Returns true if a command-line parameter
-list contains a given value.
-Example: <tt class="docutils literal"><span class="pre">(parameter_in_list</span> <span class="pre">"l",</span> <span class="pre">"pthread")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">input_languages_contain</span></tt> - Returns true if a given language
-belongs to the current input language set.
-Example: <tt class="docutils literal"><span class="pre">(input_languages_contain</span> <span class="pre">"c++")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">in_language</span></tt> - Evaluates to true if the input file language
-equals to the argument. At the moment works only with <tt class="docutils literal"><span class="pre">cmd_line</span></tt>
-and <tt class="docutils literal"><span class="pre">actions</span></tt> (on non-join nodes).
-Example: <tt class="docutils literal"><span class="pre">(in_language</span> <span class="pre">"c++")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">not_empty</span></tt> - Returns true if a given option (which should be
-either a parameter or a parameter list) is set by the
-user.
-Example: <tt class="docutils literal"><span class="pre">(not_empty</span> <span class="pre">"o")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">default</span></tt> - Always evaluates to true. Should always be the last
-test in the <tt class="docutils literal"><span class="pre">case</span></tt> expression.</li>
-<li><tt class="docutils literal"><span class="pre">and</span></tt> - A standard logical combinator that returns true iff all
-of its arguments return true. Used like this: <tt class="docutils literal"><span class="pre">(and</span> <span class="pre">(test1),</span>
-<span class="pre">(test2),</span> <span class="pre">...</span> <span class="pre">(testN))</span></tt>. Nesting of <tt class="docutils literal"><span class="pre">and</span></tt> and <tt class="docutils literal"><span class="pre">or</span></tt> is allowed,
-but not encouraged.</li>
-<li><tt class="docutils literal"><span class="pre">or</span></tt> - Another logical combinator that returns true only if any
-one of its arguments returns true. Example: <tt class="docutils literal"><span class="pre">(or</span> <span class="pre">(test1),</span>
-<span class="pre">(test2),</span> <span class="pre">...</span> <span class="pre">(testN))</span></tt>.</li>
-</ul>
-</li>
-</ul>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id17" id="writing-a-tool-description" name="writing-a-tool-description">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"><span class="pre">include/llvm/CompilerDriver/Tools.td</span></tt> file):</p>
-<pre class="literal-block">
-def llvm_gcc_cpp : Tool<[
- (in_language "c++"),
- (out_language "llvm-assembler"),
- (output_suffix "bc"),
- (cmd_line "llvm-g++ -c $INFILE -o $OUTFILE -emit-llvm"),
- (sink)
- ]>;
-</pre>
-<p>This defines a new tool called <tt class="docutils literal"><span class="pre">llvm_gcc_cpp</span></tt>, which is an alias for
-<tt class="docutils literal"><span class="pre">llvm-g++</span></tt>. As you can see, a tool definition is just a list of
-properties; most of them should be self-explanatory. The <tt class="docutils literal"><span class="pre">sink</span></tt>
-property means that this tool should be passed all command-line
-options that aren't mentioned in the option list.</p>
-<p>The complete list of all currently implemented tool properties follows.</p>
-<ul class="simple">
-<li>Possible tool properties:<ul>
-<li><tt class="docutils literal"><span class="pre">in_language</span></tt> - input language name. Can be either a string or a
-list, in case the tool supports multiple input languages.</li>
-<li><tt class="docutils literal"><span class="pre">out_language</span></tt> - output language name. Tools are not allowed to
-have multiple output languages.</li>
-<li><tt class="docutils literal"><span class="pre">output_suffix</span></tt> - output file suffix. Can also be changed
-dynamically, see documentation on actions.</li>
-<li><tt class="docutils literal"><span class="pre">cmd_line</span></tt> - the actual command used to run the tool. You can
-use <tt class="docutils literal"><span class="pre">$INFILE</span></tt> and <tt class="docutils literal"><span class="pre">$OUTFILE</span></tt> variables, output redirection
-with <tt class="docutils literal"><span class="pre">></span></tt>, hook invocations (<tt class="docutils literal"><span class="pre">$CALL</span></tt>), environment variables
-(via <tt class="docutils literal"><span class="pre">$ENV</span></tt>) and the <tt class="docutils literal"><span class="pre">case</span></tt> construct.</li>
-<li><tt class="docutils literal"><span class="pre">join</span></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"><span class="pre">sink</span></tt> - all command-line options that are not handled by other
-tools are passed to this tool.</li>
-<li><tt class="docutils literal"><span class="pre">actions</span></tt> - A single big <tt class="docutils literal"><span class="pre">case</span></tt> expression that specifies how
-this tool reacts on command-line options (described in more detail
-below).</li>
-</ul>
-</li>
-</ul>
-<div class="section">
-<h2><a class="toc-backref" href="#id18" id="actions" name="actions">Actions</a></h2>
-<p>A tool often needs to react to command-line options, and this is
-precisely what the <tt class="docutils literal"><span class="pre">actions</span></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"),
- (cmd_line "llvm-gcc $INFILE -o $OUTFILE"),
- (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"><span class="pre">actions</span></tt> tool property is implemented on top of the omnipresent
-<tt class="docutils literal"><span class="pre">case</span></tt> expression. It associates one or more different <em>actions</em>
-with given conditions - in the example, the actions are <tt class="docutils literal"><span class="pre">forward</span></tt>,
-which forwards a given option unchanged, and <tt class="docutils literal"><span class="pre">append_cmd</span></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"><span class="pre">case</span></tt>
-construct can also be used in the <tt class="docutils literal"><span class="pre">cmd_line</span></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"><span class="pre">append_cmd</span></tt> - append a string to the tool invocation
-command.
-Example: <tt class="docutils literal"><span class="pre">(case</span> <span class="pre">(switch_on</span> <span class="pre">"pthread"),</span> <span class="pre">(append_cmd</span> <span class="pre">"-lpthread"))</span></tt></li>
-<li><tt class="docutils literal"><span class="pre">forward</span></tt> - forward an option unchanged.
-Example: <tt class="docutils literal"><span class="pre">(forward</span> <span class="pre">"Wall")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">forward_as</span></tt> - Change the name of an option, but forward the
-argument unchanged.
-Example: <tt class="docutils literal"><span class="pre">(forward_as</span> <span class="pre">"O0"</span> <span class="pre">"--disable-optimization")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">output_suffix</span></tt> - modify the output suffix of this
-tool.
-Example: <tt class="docutils literal"><span class="pre">(output_suffix</span> <span class="pre">"i")</span></tt>.</li>
-<li><tt class="docutils literal"><span class="pre">stop_compilation</span></tt> - stop compilation after this tool processes
-its input. Used without arguments.</li>
-<li><tt class="docutils literal"><span class="pre">unpack_values</span></tt> - used for for splitting and forwarding
-comma-separated lists of options, e.g. <tt class="docutils literal"><span class="pre">-Wa,-foo=bar,-baz</span></tt> is
-converted to <tt class="docutils literal"><span class="pre">-foo=bar</span> <span class="pre">-baz</span></tt> and appended to the tool invocation
-command.
-Example: <tt class="docutils literal"><span class="pre">(unpack_values</span> <span class="pre">"Wa,")</span></tt>.</li>
-</ul>
-</blockquote>
-</li>
-</ul>
-</div>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id19" id="language-map" name="language-map">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 should be added only for tools that are
-linked with the root node. Since tools are not allowed to have
-multiple output languages, for nodes "inside" the graph the input and
-output languages should match. This is enforced at compile-time.</p>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id20" id="more-advanced-topics" name="more-advanced-topics">More advanced topics</a></h1>
-<div class="section">
-<h2><a class="toc-backref" href="#id21" id="hooks-and-environment-variables" name="hooks-and-environment-variables"><span id="hooks"></span>Hooks and environment variables</a></h2>
-<p>Normally, LLVMC executes programs from the system <tt class="docutils literal"><span class="pre">PATH</span></tt>. Sometimes,
-this is not sufficient: for example, we may want to specify tool names
-in the configuration file. This can be achieved via the mechanism of
-hooks - to write your own hooks, just add their definitions to the
-<tt class="docutils literal"><span class="pre">PluginMain.cpp</span></tt> or drop a <tt class="docutils literal"><span class="pre">.cpp</span></tt> file into the
-<tt class="docutils literal"><span class="pre">$LLVMC_DIR/driver</span></tt> directory. Hooks should live in the <tt class="docutils literal"><span class="pre">hooks</span></tt>
-namespace and have the signature <tt class="docutils literal"><span class="pre">std::string</span> <span class="pre">hooks::MyHookName</span>
-<span class="pre">(void)</span></tt>. They can be used from the <tt class="docutils literal"><span class="pre">cmd_line</span></tt> tool property:</p>
-<pre class="literal-block">
-(cmd_line "$CALL(MyHook)/path/to/file -o $CALL(AnotherHook)")
-</pre>
-<p>It is also possible to use environment variables in the same manner:</p>
-<pre class="literal-block">
-(cmd_line "$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"><span class="pre">case</span></tt> expression (documented <a class="reference" href="#case">above</a>):</p>
-<pre class="literal-block">
-(cmd_line
- (case
- (switch_on "E"),
- "llvm-g++ -E -x c $INFILE -o $OUTFILE",
- (default),
- "llvm-g++ -c -x c $INFILE -o $OUTFILE -emit-llvm"))
-</pre>
-</div>
-<div class="section">
-<h2><a class="toc-backref" href="#id22" id="how-plugins-are-loaded" name="how-plugins-are-loaded"><span id="priorities"></span>How plugins are loaded</a></h2>
-<p>It is possible for LLVMC plugins to depend on each other. For example,
-one can create edges between nodes defined in some other plugin. To
-make this work, however, that plugin should be loaded first. To
-achieve this, the concept of plugin priority was introduced. By
-default, every plugin has priority zero; to specify the priority
-explicitly, put the following line in your plugin's TableGen file:</p>
-<pre class="literal-block">
-def Priority : PluginPriority<$PRIORITY_VALUE>;
-# Where PRIORITY_VALUE is some integer > 0
-</pre>
-<p>Plugins are loaded in order of their (increasing) priority, starting
-with 0. Therefore, the plugin with the highest priority value will be
-loaded last.</p>
-</div>
-<div class="section">
-<h2><a class="toc-backref" href="#id23" id="debugging" name="debugging">Debugging</a></h2>
-<p>When writing LLVMC plugins, 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>. This command assumes that Graphviz <a class="footnote-reference" href="#id8" id="id5" name="id5">[2]</a> and
-Ghostview <a class="footnote-reference" href="#id9" id="id6" name="id6">[3]</a> are installed. There is also a <tt class="docutils literal"><span class="pre">--dump-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>
-</div>
-</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id24" id="references" name="references">References</a></h1>
-<table class="docutils footnote" frame="void" id="id7" rules="none">
-<colgroup><col class="label" /><col /></colgroup>
-<tbody valign="top">
-<tr><td class="label"><a class="fn-backref" href="#id1" name="id7">[1]</a></td><td>TableGen Fundamentals
-<a class="reference" href="http://llvm.cs.uiuc.edu/docs/TableGenFundamentals.html">http://llvm.cs.uiuc.edu/docs/TableGenFundamentals.html</a></td></tr>
-</tbody>
-</table>
-<table class="docutils footnote" frame="void" id="id8" rules="none">
-<colgroup><col class="label" /><col /></colgroup>
-<tbody valign="top">
-<tr><td class="label"><a class="fn-backref" href="#id5" name="id8">[2]</a></td><td>Graphviz
-<a class="reference" href="http://www.graphviz.org/">http://www.graphviz.org/</a></td></tr>
-</tbody>
-</table>
-<table class="docutils footnote" frame="void" id="id9" rules="none">
-<colgroup><col class="label" /><col /></colgroup>
-<tbody valign="top">
-<tr><td class="label"><a class="fn-backref" href="#id6" name="id9">[3]</a></td><td>Ghostview
-<a class="reference" href="http://pages.cs.wisc.edu/~ghost/">http://pages.cs.wisc.edu/~ghost/</a></td></tr>
-</tbody>
-</table>
-<hr>
+// Compilation graph
+def CompilationGraph : CompilationGraph<[Edge<"root", "gcc">]>;
+</pre>
+<p>As you can see, this file consists of three parts: tool descriptions,
+language map, and the compilation graph definition.</p>
+<p>At the heart of LLVMC is the idea of a compilation graph: vertices in
+this graph are tools, and edges represent a transformation path
+between two tools (for example, assembly source produced by the
+compiler can be transformed into executable code by an assembler). The
+compilation graph is basically a list of edges; a special node named
+<tt class="docutils literal"><span class="pre">root</span></tt> is used to mark graph entry points.</p>
+<p>Tool descriptions are represented as property lists: most properties
+in the example above should be self-explanatory; the <tt class="docutils literal"><span class="pre">sink</span></tt> property
+means that all options lacking an explicit description should be
+forwarded to this tool.</p>
+<p>The <tt class="docutils literal"><span class="pre">LanguageMap</span></tt> associates a language name with a list of suffixes
+and is used for deciding which toolchain corresponds to a given input
+file.</p>
+<p>To learn more about LLVMC customization, refer to the reference
+manual and plugin source code in the <tt class="docutils literal"><span class="pre">plugins</span></tt> directory.</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>
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+ alt="Valid CSS" /></a>
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+<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>
+<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>
+Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $
+</address></div>
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