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<h1 class="title">Customizing LLVMC: Reference Manual</h1>
+
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-<div class="contents topic">
-<p class="topic-title first"><a id="contents" name="contents">Contents</a></p>
+<div class="contents topic" id="contents">
+<p class="topic-title first">Contents</p>
<ul class="simple">
-<li><a class="reference" href="#introduction" id="id4" name="id4">Introduction</a></li>
-<li><a class="reference" href="#compiling-with-llvmc" id="id5" name="id5">Compiling with LLVMC</a></li>
-<li><a class="reference" href="#predefined-options" id="id6" name="id6">Predefined options</a></li>
-<li><a class="reference" href="#compiling-llvmc-plugins" id="id7" name="id7">Compiling LLVMC plugins</a></li>
-<li><a class="reference" href="#customizing-llvmc-the-compilation-graph" id="id8" name="id8">Customizing LLVMC: the compilation graph</a></li>
-<li><a class="reference" href="#describing-options" id="id9" name="id9">Describing options</a><ul>
-<li><a class="reference" href="#external-options" id="id10" name="id10">External options</a></li>
+<li><a class="reference internal" href="#introduction" id="id4">Introduction</a></li>
+<li><a class="reference internal" href="#compiling-with-llvmc" id="id5">Compiling with LLVMC</a></li>
+<li><a class="reference internal" href="#predefined-options" id="id6">Predefined options</a></li>
+<li><a class="reference internal" href="#compiling-llvmc-plugins" id="id7">Compiling LLVMC plugins</a></li>
+<li><a class="reference internal" href="#compiling-standalone-llvmc-based-drivers" id="id8">Compiling standalone LLVMC-based drivers</a></li>
+<li><a class="reference internal" href="#customizing-llvmc-the-compilation-graph" id="id9">Customizing LLVMC: the compilation graph</a></li>
+<li><a class="reference internal" href="#describing-options" id="id10">Describing options</a><ul>
+<li><a class="reference internal" href="#external-options" id="id11">External options</a></li>
</ul>
</li>
-<li><a class="reference" href="#conditional-evaluation" id="id11" name="id11">Conditional evaluation</a></li>
-<li><a class="reference
" href="#writing-a-tool-description" id="id12" name="id12">Writing a tool description</a><ul>
-<li><a class="reference" href="#actions" id="id13" name="id13">Actions</a></li>
+<li><a class="reference internal" href="#conditional-evaluation" id="id12">Conditional evaluation</a></li>
+<li><a class="reference
internal" href="#writing-a-tool-description" id="id13">Writing a tool description</a><ul>
+<li><a class="reference internal" href="#actions" id="id14">Actions</a></li>
</ul>
</li>
-<li><a class="reference" href="#language-map" id="id14" name="id14">Language map</a></li>
-<li><a class="reference" href="#more-advanced-topics" id="id15" name="id15">More advanced topics</a><ul>
-<li><a class="reference" href="#hooks-and-environment-variables" id="id16" name="id16">Hooks and environment variables</a></li>
-<li><a class="reference" href="#how-plugins-are-loaded" id="id17" name="id17">How plugins are loaded</a></li>
-<li><a class="reference" href="#debugging" id="id18" name="id18">Debugging</a></li>
+<li><a class="reference internal" href="#language-map" id="id15">Language map</a></li>
+<li><a class="reference internal" href="#more-advanced-topics" id="id16">More advanced topics</a><ul>
+<li><a class="reference internal" href="#hooks-and-environment-variables" id="id17">Hooks and environment variables</a></li>
+<li><a class="reference internal" href="#how-plugins-are-loaded" id="id18">How plugins are loaded</a></li>
+<li><a class="reference internal" href="#debugging" id="id19">Debugging</a></li>
+<li><a class="reference internal" href="#conditioning-on-the-executable-name" id="id20">Conditioning on the executable name</a></li>
</ul>
</li>
</ul>
</div>
<div class="doc_author">
<p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p>
-</div><div class="section">
-<h1><a class="toc-backref" href="#id4" id="introduction" name="introduction">Introduction</a></h1>
+</div><div class="section" id="introduction">
+<h1><a class="toc-backref" href="#id4">Introduction</a></h1>
<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
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 <a class="reference" href="http://llvm.cs.uiuc.edu/docs/TableGenFundamentals.html">TableGen</a> as its configuration language, you
+<p>Because LLVMC employs <a class="reference external" href="http://llvm.org/docs/TableGenFundamentals.html">TableGen</a> as its configuration language, you
need to be familiar with it to customize LLVMC.</p>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id5" id="compiling-with-llvmc" name="compiling-with-llvmc">Compiling with LLVMC</a></h1>
+<div class="section" id="compiling-with-llvmc">
+<h1><a class="toc-backref" href="#id5">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>
$ ./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>
+<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> vs. <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>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>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 <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="#id6" id="predefined-options" name="predefined-options">Predefined options</a></h1>
+<div class="section" id="predefined-options">
+<h1><a class="toc-backref" href="#id6">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">-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">--check-graph</span></tt> - Check the compilation for common errors like
-mismatched output/input language names, multiple default edges and
-cycles. Hidden option, useful for debugging.</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">--save-temps</span></tt> - Write temporary files to the current directory and do not
+delete them on exit. This option can also take an argument: the
+<tt class="docutils literal"><span class="pre">--save-temps=obj</span></tt> switch will write files into the directory specified with
+the <tt class="docutils literal"><span class="pre">-o</span></tt> option. The <tt class="docutils literal"><span class="pre">--save-temps=cwd</span></tt> and <tt class="docutils literal"><span class="pre">--save-temps</span></tt> switches are
+both synonyms for the default behaviour.</li>
+<li><tt class="docutils literal"><span class="pre">--temp-dir</span> <span class="pre">DIRECTORY</span></tt> - Store temporary files in the given directory. This
+directory is deleted on exit unless <tt class="docutils literal"><span class="pre">--save-temps</span></tt> is specified. If
+<tt class="docutils literal"><span class="pre">--save-temps=obj</span></tt> is also specified, <tt class="docutils literal"><span class="pre">--temp-dir</span></tt> is given the
+precedence.</li>
+<li><tt class="docutils literal"><span class="pre">--check-graph</span></tt> - Check the compilation for common errors like mismatched
+output/input language names, multiple default edges and cycles. Because of
+plugins, these checks can't be performed at compile-time. Exit with code zero
+if no errors were found, and return the number of found errors
+otherwise. Hidden option, useful for debugging LLVMC plugins.</li>
+<li><tt class="docutils literal"><span class="pre">--view-graph</span></tt> - Show a graphical representation of the compilation graph
+and exit. 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 LLVMC plugins.</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 Graphviz format (identical
+to the file used by the <tt class="docutils literal"><span class="pre">--view-graph</span></tt> option). The <tt class="docutils literal"><span class="pre">-o</span></tt> option can be
+used to set the output file name. Hidden option, useful for debugging LLVMC
+plugins.</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="#id7" id="compiling-llvmc-plugins" name="compiling-llvmc-plugins">Compiling LLVMC plugins</a></h1>
+<div class="section" id="compiling-llvmc-plugins">
+<h1><a class="toc-backref" href="#id7">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">
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>
+can also contain hook definitions (see <a class="reference internal" 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">
$ 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">plugin_llvmc_$(LLVMC_PLUGIN).$(DLL_EXTENSION)</span></tt> (in our case,
+<tt class="docutils literal"><span class="pre">plugin_llvmc_MyPlugin.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 $LLVM_DIR/Release/lib/LLVMCSimple.so
+$ llvmc -load $LLVM_DIR/Release/lib/plugin_llvmc_Simple.so
+</pre>
+</div>
+<div class="section" id="compiling-standalone-llvmc-based-drivers">
+<h1><a class="toc-backref" href="#id8">Compiling standalone LLVMC-based drivers</a></h1>
+<p>By default, the <tt class="docutils literal"><span class="pre">llvmc</span></tt> executable consists of a driver core plus several
+statically linked plugins (<tt class="docutils literal"><span class="pre">Base</span></tt> and <tt class="docutils literal"><span class="pre">Clang</span></tt> at the moment). You can
+produce a standalone LLVMC-based driver executable by linking the core with your
+own plugins. The recommended way to do this is by starting with the provided
+<tt class="docutils literal"><span class="pre">Skeleton</span></tt> example (<tt class="docutils literal"><span class="pre">$LLVMC_DIR/example/Skeleton</span></tt>):</p>
+<pre class="literal-block">
+$ cd $LLVMC_DIR/example/
+$ cp -r Skeleton mydriver
+$ cd mydriver
+$ vim Makefile
+[...]
+$ make
</pre>
+<p>If you're compiling LLVM with different source and object directories, then you
+must perform the following additional steps before running <tt class="docutils literal"><span class="pre">make</span></tt>:</p>
+<pre class="literal-block">
+# LLVMC_SRC_DIR = $LLVM_SRC_DIR/tools/llvmc/
+# LLVMC_OBJ_DIR = $LLVM_OBJ_DIR/tools/llvmc/
+$ cp $LLVMC_SRC_DIR/example/mydriver/Makefile \
+ $LLVMC_OBJ_DIR/example/mydriver/
+$ cd $LLVMC_OBJ_DIR/example/mydriver
+$ make
+</pre>
+<p>Another way to do the same thing is by using the following command:</p>
+<pre class="literal-block">
+$ cd $LLVMC_DIR
+$ make LLVMC_BUILTIN_PLUGINS=MyPlugin LLVMC_BASED_DRIVER_NAME=mydriver
+</pre>
+<p>This works with both srcdir == objdir and srcdir != objdir, but assumes that the
+plugin source directory was placed under <tt class="docutils literal"><span class="pre">$LLVMC_DIR/plugins</span></tt>.</p>
<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=""
+$ make LLVMC_BUILTIN_PLUGINS=""
</pre>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id8" id="customizing-llvmc-the-compilation-graph" name="customizing-llvmc-the-compilation-graph">Customizing LLVMC: the compilation graph</a></h1>
+<div class="section" id="customizing-llvmc-the-compilation-graph">
+<h1><a class="toc-backref" href="#id9">Customizing LLVMC: the compilation graph</a></h1>
<p>Each TableGen configuration file should include the common
definitions:</p>
<pre class="literal-block">
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="#id9" id="describing-options" name="describing-options">Describing options</a></h1>
+<div class="section" id="describing-options">
+<h1><a class="toc-backref" href="#id10">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">
special cases). Usage example: <tt class="docutils literal"><span class="pre">(parameter_list_option</span> <span class="pre">"foo",</span> <span class="pre">(multi_val</span>
<span class="pre">3))</span></tt>. Only list options can have this attribute; you can, however, use
the <tt class="docutils literal"><span class="pre">one_or_more</span></tt> and <tt class="docutils literal"><span class="pre">zero_or_one</span></tt> properties.</li>
+<li><tt class="docutils literal"><span class="pre">init</span></tt> - this option has a default value, either a string (if it is a
+parameter), or a boolean (if it is a switch; boolean constants are called
+<tt class="docutils literal"><span class="pre">true</span></tt> and <tt class="docutils literal"><span class="pre">false</span></tt>). List options can't have this attribute. Usage
+examples: <tt class="docutils literal"><span class="pre">(switch_option</span> <span class="pre">"foo",</span> <span class="pre">(init</span> <span class="pre">true))</span></tt>; <tt class="docutils literal"><span class="pre">(prefix_option</span> <span class="pre">"bar",</span>
+<span class="pre">(init</span> <span class="pre">"baz"))</span></tt>.</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="#id10" id="external-options" name="external-options">External options</a></h2>
+<div class="section" id="external-options">
+<h2><a class="toc-backref" href="#id11">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 must be marked as
(switch_option "E", (extern))
...
</pre>
-<p>See also the section on plugin <a class="reference" href="#priorities">priorities</a>.</p>
+<p>If an external option has additional attributes besides 'extern', they are
+ignored. See also the section on plugin <a class="reference internal" href="#priorities">priorities</a>.</p>
</div>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id11" id="conditional-evaluation" name="conditional-evaluation"><span id="case"></span>Conditional evaluation</a></h1>
+<div class="section" id="conditional-evaluation">
+<span id="case"></span><h1><a class="toc-backref" href="#id12">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'
</li>
</ul>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id12" id="writing-a-tool-description" name="writing-a-tool-description">Writing a tool description</a></h1>
+<div class="section" id="writing-a-tool-description">
+<h1><a class="toc-backref" href="#id13">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>
</ul>
</li>
</ul>
-<div class="section">
-<h2><a class="toc-backref" href="#id13" id="actions" name="actions">Actions</a></h2>
+<div class="section" id="actions">
+<h2><a class="toc-backref" href="#id14">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>
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>
+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>
</ul>
</div>
</div>
-<div class="section">
-<h1><a class="toc-backref" href="#id14" id="language-map" name="language-map">Language map</a></h1>
+<div class="section" id="language-map">
+<h1><a class="toc-backref" href="#id15">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
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="#id15" id="more-advanced-topics" name="more-advanced-topics">More advanced topics</a></h1>
-<div class="section">
-<h2><a class="toc-backref" href="#id16" id="hooks-and-environment-variables" name="hooks-and-environment-variables"><span id="hooks"></span>Hooks and environment variables</a></h2>
+<div class="section" id="more-advanced-topics">
+<h1><a class="toc-backref" href="#id16">More advanced topics</a></h1>
+<div class="section" id="hooks-and-environment-variables">
+<span id="hooks"></span><h2><a class="toc-backref" href="#id17">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 paths
or names in the configuration file. This can be easily achieved via
(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>
+the <tt class="docutils literal"><span class="pre">case</span></tt> expression (documented <a class="reference internal" href="#case">above</a>):</p>
<pre class="literal-block">
(cmd_line
(case
"llvm-g++ -c -x c $INFILE -o $OUTFILE -emit-llvm"))
</pre>
</div>
-<div class="section">
-<h2><a class="toc-backref" href="#id17" id="how-plugins-are-loaded" name="how-plugins-are-loaded"><span id="priorities"></span>How plugins are loaded</a></h2>
+<div class="section" id="how-plugins-are-loaded">
+<span id="priorities"></span><h2><a class="toc-backref" href="#id18">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
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="#id18" id="debugging" name="debugging">Debugging</a></h2>
+<div class="section" id="debugging">
+<h2><a class="toc-backref" href="#id19">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 <a class="reference" href="http://www.graphviz.org/">Graphviz</a> and
-<a class="reference" href="http://pages.cs.wisc.edu/~ghost/">Ghostview</a> are installed. There is also a <tt class="docutils literal"><span class="pre">--dump-graph</span></tt> option that
+line option <tt class="docutils literal"><span class="pre">--view-graph</span></tt>. This command assumes that <a class="reference external" href="http://www.graphviz.org/">Graphviz</a> and
+<a class="reference external" href="http://pages.cs.wisc.edu/~ghost/">Ghostview</a> are installed. There is also a <tt class="docutils literal"><span class="pre">--write-graph</span></tt> option that
creates a Graphviz source file (<tt class="docutils literal"><span class="pre">compilation-graph.dot</span></tt>) in the
current directory.</p>
<p>Another useful <tt class="docutils literal"><span class="pre">llvmc</span></tt> option is <tt class="docutils literal"><span class="pre">--check-graph</span></tt>. It checks the
dynamically. When invoked with <tt class="docutils literal"><span class="pre">--check-graph</span></tt>, <tt class="docutils literal"><span class="pre">llvmc</span></tt> doesn't
perform any compilation tasks and returns the number of encountered
errors as its status code.</p>
+</div>
+<div class="section" id="conditioning-on-the-executable-name">
+<h2><a class="toc-backref" href="#id20">Conditioning on the executable name</a></h2>
+<p>For now, the executable name (the value passed to the driver in <tt class="docutils literal"><span class="pre">argv[0]</span></tt>) is
+accessible only in the C++ code (i.e. hooks). Use the following code:</p>
+<pre class="literal-block">
+namespace llvmc {
+extern const char* ProgramName;
+}
+
+std::string MyHook() {
+//...
+if (strcmp(ProgramName, "mydriver") == 0) {
+ //...
+
+}
+</pre>
+<p>In general, you're encouraged not to make the behaviour dependent on the
+executable file name, and use command-line switches instead. See for example how
+the <tt class="docutils literal"><span class="pre">Base</span></tt> plugin behaves when it needs to choose the correct linker options
+(think <tt class="docutils literal"><span class="pre">g++</span></tt> vs. <tt class="docutils literal"><span class="pre">gcc</span></tt>).</p>
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