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| author | Mikhail Glushenkov <foldr@codedgers.com> | 2008-12-11 23:33:33 +0000 |
|---|---|---|
| committer | Mikhail Glushenkov <foldr@codedgers.com> | 2008-12-11 23:33:33 +0000 |
| commit | 99a3a2c44c7735cafab8d60fef16c63b7187e76a (patch) | |
| tree | 83cb925507dbb423b26372db1c61d4c3ba382757 /docs/CompilerDriverTutorial.html | |
| parent | 68319f87cc07756e29c6b98efd934577312561ec (diff) | |
| download | external_llvm-99a3a2c44c7735cafab8d60fef16c63b7187e76a.zip external_llvm-99a3a2c44c7735cafab8d60fef16c63b7187e76a.tar.gz external_llvm-99a3a2c44c7735cafab8d60fef16c63b7187e76a.tar.bz2 | |
Use correct file for the llvmc tutorial.
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| -rw-r--r-- | docs/CompilerDriverTutorial.html | 617 |
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diff --git a/docs/CompilerDriverTutorial.html b/docs/CompilerDriverTutorial.html index 2eb452a..cc47075 100644 --- a/docs/CompilerDriverTutorial.html +++ b/docs/CompilerDriverTutorial.html @@ -4,13 +4,13 @@ <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.4.1: http://docutils.sourceforge.net/" /> -<title>Customizing LLVMC: Reference Manual</title> +<title>Tutorial - Using LLVMC</title> <meta name="author" content="Mikhail Glushenkov <foldr@codedegers.com>" /> <link rel="stylesheet" href="llvm-rst.css" type="text/css" /> </head> <body> -<div class="document" id="customizing-llvmc-reference-manual"> -<h1 class="title">Customizing LLVMC: Reference Manual</h1> +<div class="document" id="tutorial-using-llvmc"> +<h1 class="title">Tutorial - Using LLVMC</h1> <table class="docinfo" frame="void" rules="none"> <col class="docinfo-name" /> <col class="docinfo-content" /> @@ -19,574 +19,99 @@ <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> +<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 class="contents topic"> <p class="topic-title first"><a id="contents" name="contents">Contents</a></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" href="#compiling-with-llvmc" id="id3" name="id3">Compiling with LLVMC</a></li> +<li><a class="reference" href="#using-llvmc-to-generate-toolchain-drivers" id="id4" name="id4">Using LLVMC to generate toolchain drivers</a></li> +<li><a class="reference" href="#references" id="id5" name="id5">References</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> +<h1><a class="toc-backref" href="#id3" id="compiling-with-llvmc" name="compiling-with-llvmc">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> +<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="#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> -</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> -<pre class="literal-block"> +<h1><a class="toc-backref" href="#id4" id="using-llvmc-to-generate-toolchain-drivers" name="using-llvmc-to-generate-toolchain-drivers">Using LLVMC to generate toolchain drivers</a></h1> +<p>LLVMC plugins are written mostly using TableGen <a class="footnote-reference" href="#id2" id="id1" name="id1">[1]</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">plugins/Simple/Simple.td</span></tt>, which is a primitive +wrapper for <tt class="docutils literal"><span class="pre">gcc</span></tt>:</p> +<pre class="literal-block"> +$ cd $LLVM_DIR/tools/llvmc +$ make DRIVER_NAME=mygcc 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 standalone dynamic library; 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>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">, - ... - - Edge<"llvm_gcc_c", "llc">, - Edge<"llvm_gcc_cpp", "llc">, - ... - - 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))>, - ... - - ]>; -</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)) +// Language map +def LanguageMap : LanguageMap<[LangToSuffixes<"c", ["c"]>]>; -// 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"><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> +// 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> </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"> +<h1><a class="toc-backref" href="#id5" id="references" name="references">References</a></h1> +<table class="docutils footnote" frame="void" id="id2" 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 +<tr><td class="label"><a class="fn-backref" href="#id1" name="id2">[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> <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> |