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| author | Mikhail Glushenkov <foldr@codedgers.com> | 2008-12-11 23:24:40 +0000 |
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| committer | Mikhail Glushenkov <foldr@codedgers.com> | 2008-12-11 23:24:40 +0000 |
| commit | 68319f87cc07756e29c6b98efd934577312561ec (patch) | |
| tree | 073cfd59b39c6ce4692eb294097d797797c826f8 /docs/CompilerDriverTutorial.html | |
| parent | ba71d677dde1911972d66a321811c3f8f9dbf0af (diff) | |
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diff --git a/docs/CompilerDriverTutorial.html b/docs/CompilerDriverTutorial.html new file mode 100644 index 0000000..2eb452a --- /dev/null +++ b/docs/CompilerDriverTutorial.html @@ -0,0 +1,603 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> +<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> +<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> +<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> +<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> +</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> +<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> +</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"> +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") +... +]>; +</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". + +(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> +<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/referer"><img src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></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> +</body> +</html> |