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Add notes about MF.viewCFG() and friends.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23765 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2005-10-17 01:36:23 +00:00
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docs/ProgrammersManual.html
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@ -41,6 +41,7 @@ option</a></li>
<li>The <tt>InstVisitor</tt> template
<li>The general graph API
-->
<li><a href="#ViewGraph">Viewing graphs while debugging code</a></li>
</ul>
</li>
<li><a href="#common">Helpful Hints for Common Operations</a>
@ -491,6 +492,44 @@ maintainable and useful.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="ViewGraph">Viewing graphs while debugging code</a>
</div>
<div class="doc_text">
<p>Several of the important data structures in LLVM are graphs: for example
CFGs made out of LLVM <a href="#BasicBlock">BasicBlock</a>s, CFGs made out of
LLVM <a href="CodeGenerator.html#machinebasicblock">MachineBasicBlock</a>s, and
<a href="CodeGenerator.html#selectiondag_intro">Instruction Selection
DAGs</a>. In many cases, while debugging various parts of the compiler, it is
nice to instantly visualize these graphs.</p>
<p>LLVM provides several callbacks that are available in a debug build to do
exactly that. If you call the <tt>Function::viewCFG()</tt> method, for example,
the current LLVM tool will pop up a window containing the CFG for the function
where each basic block is a node in the graph, and each node contains the
instructions in the block. Similarly, there also exists
<tt>Function::viewCFGOnly()</tt> (does not include the instructions), the
<tt>MachineFunction::viewCFG()</tt> and <tt>MachineFunction::viewCFGOnly()</tt>,
and the <tt>SelectionDAG::viewGraph()</tt> methods. Within GDB, for example,
you can usually use something like "<tt>call DAG.viewGraph()</tt>" to pop
up a window. Alternatively, you can sprinkle calls to these functions in your
code in places you want to debug.</p>
<p>Getting this to work requires a small amount of configuration. On Unix
systems with X11, install the <a href="http://www.graphviz.org">graphviz</a>
toolkit, and make sure 'dot' and 'gv' are in your path. If you are running on
Mac OS/X, download and install the Mac OS/X <a
href="http://www.pixelglow.com/graphviz/">Graphviz program</a>, and add
<tt>/Applications/Graphviz.app/Contents/MacOS/</tt> (or whereever you install
it) to your path. Once in your system and path are set up, rerun the LLVM
configure script and rebuild LLVM to enable this functionality.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="common">Helpful Hints for Common Operations</a>