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            <div class="doc_title">

            
              LLVM Programmer's Manual

            
            </div>


            <ol>

            
              <li><a href="#introduction">Introduction</a></li>

            
              <li><a href="#general">General Information</a>

            
                <ul>

            
                  <li><a href="#stl">The C++ Standard Template Library</a><!--

            
                <li>The <tt>-time-passes</tt> option

            
                <li>How to use the LLVM Makefile system

            
                <li>How to write a regression test

            
            --> </li>

            
                </ul>

            
              </li>

            
              <li><a href="#apis">Important and useful LLVM APIs</a>

            
                <ul>

            
                  <li><a href="#isa">The <tt>isa&lt;&gt;</tt>, <tt>cast&lt;&gt;</tt>

            
            and <tt>dyn_cast&lt;&gt;</tt> templates</a> </li>

            
                  <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro &amp; <tt>-debug</tt>

            
            option</a>

            
                    <ul>

            
                      <li><a href="#DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt>

            
            and the <tt>-debug-only</tt> option</a> </li>

            
                    </ul>

            
                  </li>

            
                  <li><a href="#Statistic">The <tt>Statistic</tt> template &amp; <tt>-stats</tt>

            
            option</a><!--

            
                <li>The <tt>InstVisitor</tt> template

            
                <li>The general graph API

            
            --> </li>

            
                </ul>

            
              </li>

            
              <li><a href="#common">Helpful Hints for Common Operations</a>

            
                <ul>

            
                  <li><a href="#inspection">Basic Inspection and Traversal Routines</a>

            
                    <ul>

            
                      <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s

            
            in a <tt>Function</tt></a> </li>

            
                      <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s

            
            in a <tt>BasicBlock</tt></a> </li>

            
                      <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s

            
            in a <tt>Function</tt></a> </li>

            
                      <li><a href="#iterate_convert">Turning an iterator into a

            
            class pointer</a> </li>

            
                      <li><a href="#iterate_complex">Finding call sites: a more

            
            complex example</a> </li>

            
                      <li><a href="#calls_and_invokes">Treating calls and invokes

            
            the same way</a> </li>

            
                      <li><a href="#iterate_chains">Iterating over def-use &amp;

            
            use-def chains</a> </li>

            
                    </ul>

            
                  </li>

            
                  <li><a href="#simplechanges">Making simple changes</a>

            
                    <ul>

            
                      <li><a href="#schanges_creating">Creating and inserting new

            
            		 <tt>Instruction</tt>s</a> </li>

            
                      <li><a href="#schanges_deleting">Deleting 		 <tt>Instruction</tt>s</a> </li>

            
                      <li><a href="#schanges_replacing">Replacing an 		 <tt>Instruction</tt>

            
            with another <tt>Value</tt></a> </li>

            
                    </ul>

            
            <!--

            
                <li>Working with the Control Flow Graph

            
                <ul>

            
                  <li>Accessing predecessors and successors of a <tt>BasicBlock</tt>

            
                  <li>

            
                  <li>

            
                </ul>

            
            --> </li>

            
                </ul>

            
              </li>

            
              <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>

            
                <ul>

            
                <li><a href="#Value">The <tt>Value</tt> class</a>

            
                  <ul>

            
                  <li><a href="#User">The <tt>User</tt> class</a>

            
                    <ul>

            
                      <li><a href="#Instruction">The <tt>Instruction</tt> class</a>

            
                        <ul>

            
            	      <li><a href="#GetElementPtrInst">The <tt>GetElementPtrInst</tt>

            
            		    class</a></li>

            
                        </ul></li>

            
                      <li><a href="#Module">The <tt>Module</tt> class</a></li>

            
                      <li><a href="#Constant">The <tt>Constant</tt> class</a>

            
            	    <ul>

            
            	      <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>

            
            	      <ul>

            
            		<li><a href="#BasicBlock">The <tt>BasicBlock</tt>class</a></li>

            
            		<li><a href="#Function">The <tt>Function</tt> class</a></li>

            
            		<li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class

            
            		  </a></li>

            
            	      </ul></li>

            
            	    </ul>

            
            	  </li>

            
                      <li><a href="#Type">The <tt>Type</tt> class</a> </li>

            
                      <li><a href="#Argument">The <tt>Argument</tt> class</a></li>

            
                    </ul></li>

            
                </ul></li>

            
                <li><a href="#SymbolTable">The <tt>SymbolTable</tt> class </a></li>

            
                <li>The <tt>ilist</tt> and <tt>iplist</tt> classes

            
                  <ul>

            
            	<li>Creating, inserting, moving and deleting from LLVM lists </li>

            
                  </ul>

            
                </li>

            
                <li>Important iterator invalidation semantics to be aware of.</li>

            
              </li>

            
            </ol>


            <div class="doc_author">

            
              <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>,

            
                            <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>,

            
                            <a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a>, and

            
                            <a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p>

            
            </div>


            <!-- *********************************************************************** -->

            
            <div class="doc_section">

            
              <a name="introduction">Introduction </a>

            
            </div>

            
            <!-- *********************************************************************** -->


            <div class="doc_text">


            <p>This document is meant to highlight some of the important classes and

            
            interfaces available in the LLVM source-base.  This manual is not

            
            intended to explain what LLVM is, how it works, and what LLVM code looks

            
            like.  It assumes that you know the basics of LLVM and are interested

            
            in writing transformations or otherwise analyzing or manipulating the

            
            code.</p>


            <p>This document should get you oriented so that you can find your

            
            way in the continuously growing source code that makes up the LLVM

            
            infrastructure. Note that this manual is not intended to serve as a

            
            replacement for reading the source code, so if you think there should be

            
            a method in one of these classes to do something, but it's not listed,

            
            check the source.  Links to the <a href="/doxygen/">doxygen</a> sources

            
            are provided to make this as easy as possible.</p>


            <p>The first section of this document describes general information that is

            
            useful to know when working in the LLVM infrastructure, and the second describes

            
            the Core LLVM classes.  In the future this manual will be extended with

            
            information describing how to use extension libraries, such as dominator

            
            information, CFG traversal routines, and useful utilities like the <tt><a

            
            href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.</p>


            </div>


            <!-- *********************************************************************** -->

            
            <div class="doc_section">

            
              <a name="general">General Information</a>

            
            </div>

            
            <!-- *********************************************************************** -->


            <div class="doc_text">


            <p>This section contains general information that is useful if you are working

            
            in the LLVM source-base, but that isn't specific to any particular API.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="stl">The C++ Standard Template Library</a>

            
            </div>


            <div class="doc_text">


            <p>LLVM makes heavy use of the C++ Standard Template Library (STL),

            
            perhaps much more than you are used to, or have seen before.  Because of

            
            this, you might want to do a little background reading in the

            
            techniques used and capabilities of the library.  There are many good

            
            pages that discuss the STL, and several books on the subject that you

            
            can get, so it will not be discussed in this document.</p>


            <p>Here are some useful links:</p>


            <ol>


            <li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++ Library

            
            reference</a> - an excellent reference for the STL and other parts of the

            
            standard C++ library.</li>


            <li><a href="http://www.tempest-sw.com/cpp/">C++ In a Nutshell</a> - This is an

            
            O'Reilly book in the making.  It has a decent

            
            Standard Library

            
            Reference that rivals Dinkumware's, and is unfortunately no longer free since the book has been

            
            published.</li>


            <li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked

            
            Questions</a></li>


            <li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -

            
            Contains a useful <a

            
            href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the

            
            STL</a>.</li>


            <li><a href="http://www.research.att.com/%7Ebs/C++.html">Bjarne Stroustrup's C++

            
            Page</a></li>


            <li><a href="http://www.linux.com.cn/Bruce_Eckel/TICPPv2/Contents.htm">

            
            Bruce Eckel's Thinking in C++, 2nd ed. Volume 2 Revision 4.0 (even better, get

            
            the book).</a></li>


            </ol>


            <p>You are also encouraged to take a look at the <a

            
            href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how

            
            to write maintainable code more than where to put your curly braces.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="stl">Other useful references</a>

            
            </div>


            <div class="doc_text">


            <ol>

            
            <li><a href="http://www.psc.edu/%7Esemke/cvs_branches.html">CVS

            
            Branch and Tag Primer</a></li>

            
            <li><a href="http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html">Using

            
            static and shared libraries across platforms</a></li>

            
            </ol>


            </div>


            <!-- *********************************************************************** -->

            
            <div class="doc_section">

            
              <a name="apis">Important and useful LLVM APIs</a>

            
            </div>

            
            <!-- *********************************************************************** -->


            <div class="doc_text">


            <p>Here we highlight some LLVM APIs that are generally useful and good to

            
            know about when writing transformations.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="isa">The isa&lt;&gt;, cast&lt;&gt; and dyn_cast&lt;&gt; templates</a>

            
            </div>


            <div class="doc_text">


            <p>The LLVM source-base makes extensive use of a custom form of RTTI.

            
            These templates have many similarities to the C++ <tt>dynamic_cast&lt;&gt;</tt>

            
            operator, but they don't have some drawbacks (primarily stemming from

            
            the fact that <tt>dynamic_cast&lt;&gt;</tt> only works on classes that

            
            have a v-table). Because they are used so often, you must know what they

            
            do and how they work. All of these templates are defined in the <a

            
             href="/doxygen/Casting_8h-source.html"><tt>Support/Casting.h</tt></a>

            
            file (note that you very rarely have to include this file directly).</p>


            <dl>

            
              <dt><tt>isa&lt;&gt;</tt>: </dt>


              <dd>The <tt>isa&lt;&gt;</tt> operator works exactly like the Java

            
              "<tt>instanceof</tt>" operator.  It returns true or false depending on whether

            
              a reference or pointer points to an instance of the specified class.  This can

            
              be very useful for constraint checking of various sorts (example below).</dd>


              <dt><tt>cast&lt;&gt;</tt>: </dt>


              <dd>The <tt>cast&lt;&gt;</tt> operator is a "checked cast" operation. It

            
              converts a pointer or reference from a base class to a derived cast, causing

            
              an assertion failure if it is not really an instance of the right type.  This

            
              should be used in cases where you have some information that makes you believe

            
              that something is of the right type.  An example of the <tt>isa&lt;&gt;</tt>

            
              and <tt>cast&lt;&gt;</tt> template is:


              <pre>

            
              static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const Loop *L) {

            
                if (isa&lt;<a href="#Constant">Constant</a>&gt;(V) || isa&lt;<a href="#Argument">Argument</a>&gt;(V) || isa&lt;<a href="#GlobalValue">GlobalValue</a>&gt;(V))

            
                  return true;


              <i>// Otherwise, it must be an instruction...</i>

            
              return !L-&gt;contains(cast&lt;<a href="#Instruction">Instruction</a>&gt;(V)-&gt;getParent());

            
              </pre>


              <p>Note that you should <b>not</b> use an <tt>isa&lt;&gt;</tt> test followed

            
              by a <tt>cast&lt;&gt;</tt>, for that use the <tt>dyn_cast&lt;&gt;</tt>

            
              operator.</p>


              </dd>


              <dt><tt>dyn_cast&lt;&gt;</tt>:</dt>


              <dd>The <tt>dyn_cast&lt;&gt;</tt> operator is a "checking cast" operation. It

            
              checks to see if the operand is of the specified type, and if so, returns a

            
              pointer to it (this operator does not work with references). If the operand is

            
              not of the correct type, a null pointer is returned.  Thus, this works very

            
              much like the <tt>dynamic_cast</tt> operator in C++, and should be used in the

            
              same circumstances.  Typically, the <tt>dyn_cast&lt;&gt;</tt> operator is used

            
              in an <tt>if</tt> statement or some other flow control statement like this:


               <pre>

            
                 if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast&lt;<a href="#AllocationInst">AllocationInst</a>&gt;(Val)) {

            
                   ...

            
                 }

            
               </pre>


               <p> This form of the <tt>if</tt> statement effectively combines together a

            
               call to <tt>isa&lt;&gt;</tt> and a call to <tt>cast&lt;&gt;</tt> into one

            
               statement, which is very convenient.</p>


               <p> Another common example is:</p>


               <pre>

            
                 <i>// Loop over all of the phi nodes in a basic block</i>

            
                 BasicBlock::iterator BBI = BB-&gt;begin();

            
                 for (; <a href="#PhiNode">PHINode</a> *PN = dyn_cast&lt;<a href="#PHINode">PHINode</a>&gt;(BBI); ++BBI)

            
                   std::cerr &lt;&lt; *PN;

            
               </pre>


               <p>Note that the <tt>dyn_cast&lt;&gt;</tt> operator, like C++'s

            
               <tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused.

            
               In particular you should not use big chained <tt>if/then/else</tt> blocks to

            
               check for lots of different variants of classes.  If you find yourself

            
               wanting to do this, it is much cleaner and more efficient to use the

            
               InstVisitor class to dispatch over the instruction type directly.</p>


                </dd>


                <dt><tt>cast_or_null&lt;&gt;</tt>: </dt>


                <dd>The <tt>cast_or_null&lt;&gt;</tt> operator works just like the

            
                <tt>cast&lt;&gt;</tt> operator, except that it allows for a null pointer as

            
                an argument (which it then propagates).  This can sometimes be useful,

            
                allowing you to combine several null checks into one.</dd>


                <dt><tt>dyn_cast_or_null&lt;&gt;</tt>: </dt>


                <dd>The <tt>dyn_cast_or_null&lt;&gt;</tt> operator works just like the

            
                <tt>dyn_cast&lt;&gt;</tt> operator, except that it allows for a null pointer

            
                as an argument (which it then propagates).  This can sometimes be useful,

            
                allowing you to combine several null checks into one.</dd>


              </dl>


            <p>These five templates can be used with any classes, whether they have a

            
            v-table or not.  To add support for these templates, you simply need to add

            
            <tt>classof</tt> static methods to the class you are interested casting

            
            to. Describing this is currently outside the scope of this document, but there

            
            are lots of examples in the LLVM source base.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="DEBUG">The <tt>DEBUG()</tt> macro &amp; <tt>-debug</tt> option</a>

            
            </div>


            <div class="doc_text">


            <p>Often when working on your pass you will put a bunch of debugging printouts

            
            and other code into your pass.  After you get it working, you want to remove

            
            it... but you may need it again in the future (to work out new bugs that you run

            
            across).</p>


            <p> Naturally, because of this, you don't want to delete the debug printouts,

            
            but you don't want them to always be noisy.  A standard compromise is to comment

            
            them out, allowing you to enable them if you need them in the future.</p>


            <p>The "<tt><a href="/doxygen/Debug_8h-source.html">Support/Debug.h</a></tt>"

            
            file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to

            
            this problem.  Basically, you can put arbitrary code into the argument of the

            
            <tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other

            
            tool) is run with the '<tt>-debug</tt>' command line argument:</p>


              <pre>     ... <br>     DEBUG(std::cerr &lt;&lt; "I am here!\n");<br>     ...<br></pre>


            <p>Then you can run your pass like this:</p>


              <pre>  $ opt &lt; a.bc &gt; /dev/null -mypass<br>    &lt;no output&gt;<br>  $ opt &lt; a.bc &gt; /dev/null -mypass -debug<br>    I am here!<br>  $<br></pre>


            <p>Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you

            
            to not have to create "yet another" command line option for the debug output for

            
            your pass.  Note that <tt>DEBUG()</tt> macros are disabled for optimized builds,

            
            so they do not cause a performance impact at all (for the same reason, they

            
            should also not contain side-effects!).</p>


            <p>One additional nice thing about the <tt>DEBUG()</tt> macro is that you can

            
            enable or disable it directly in gdb.  Just use "<tt>set DebugFlag=0</tt>" or

            
            "<tt>set DebugFlag=1</tt>" from the gdb if the program is running.  If the

            
            program hasn't been started yet, you can always just run it with

            
            <tt>-debug</tt>.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE()</tt> and

            
              the <tt>-debug-only</tt> option</a>

            
            </div>


            <div class="doc_text">


            <p>Sometimes you may find yourself in a situation where enabling <tt>-debug</tt>

            
            just turns on <b>too much</b> information (such as when working on the code

            
            generator).  If you want to enable debug information with more fine-grained

            
            control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only

            
            option as follows:</p>


              <pre>     ...<br>     DEBUG(std::cerr &lt;&lt; "No debug type\n");<br>     #undef  DEBUG_TYPE<br>     #define DEBUG_TYPE "foo"<br>     DEBUG(std::cerr &lt;&lt; "'foo' debug type\n");<br>     #undef  DEBUG_TYPE<br>     #define DEBUG_TYPE "bar"<br>     DEBUG(std::cerr &lt;&lt; "'bar' debug type\n");<br>     #undef  DEBUG_TYPE<br>     #define DEBUG_TYPE ""<br>     DEBUG(std::cerr &lt;&lt; "No debug type (2)\n");<br>     ...<br></pre>


            <p>Then you can run your pass like this:</p>


              <pre>  $ opt &lt; a.bc &gt; /dev/null -mypass<br>    &lt;no output&gt;<br>  $ opt &lt; a.bc &gt; /dev/null -mypass -debug<br>    No debug type<br>    'foo' debug type<br>    'bar' debug type<br>    No debug type (2)<br>  $ opt &lt; a.bc &gt; /dev/null -mypass -debug-only=foo<br>    'foo' debug type<br>  $ opt &lt; a.bc &gt; /dev/null -mypass -debug-only=bar<br>    'bar' debug type<br>  $<br></pre>


            <p>Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of

            
            a file, to specify the debug type for the entire module (if you do this before

            
            you <tt>#include "Support/Debug.h"</tt>, you don't have to insert the ugly

            
            <tt>#undef</tt>'s).  Also, you should use names more meaningful than "foo" and

            
            "bar", because there is no system in place to ensure that names do not

            
            conflict. If two different modules use the same string, they will all be turned

            
            on when the name is specified. This allows, for example, all debug information

            
            for instruction scheduling to be enabled with <tt>-debug-type=InstrSched</tt>,

            
            even if the source lives in multiple files.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Statistic">The <tt>Statistic</tt> template &amp; <tt>-stats</tt>

            
              option</a>

            
            </div>


            <div class="doc_text">


            <p>The "<tt><a

            
            href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>" file

            
            provides a template named <tt>Statistic</tt> that is used as a unified way to

            
            keep track of what the LLVM compiler is doing and how effective various

            
            optimizations are.  It is useful to see what optimizations are contributing to

            
            making a particular program run faster.</p>


            <p>Often you may run your pass on some big program, and you're interested to see

            
            how many times it makes a certain transformation.  Although you can do this with

            
            hand inspection, or some ad-hoc method, this is a real pain and not very useful

            
            for big programs.  Using the <tt>Statistic</tt> template makes it very easy to

            
            keep track of this information, and the calculated information is presented in a

            
            uniform manner with the rest of the passes being executed.</p>


            <p>There are many examples of <tt>Statistic</tt> uses, but the basics of using

            
            it are as follows:</p>


            <ol>

            
                <li>Define your statistic like this:

            
                  <pre>static Statistic&lt;&gt; NumXForms("mypassname", "The # of times I did stuff");<br></pre>


                  <p>The <tt>Statistic</tt> template can emulate just about any data-type,

            
                  but if you do not specify a template argument, it defaults to acting like

            
                  an unsigned int counter (this is usually what you want).</p></li>


                <li>Whenever you make a transformation, bump the counter:

            
                  <pre>   ++NumXForms;   // I did stuff<br></pre>

            
                </li>

            
              </ol>


              <p>That's all you have to do.  To get '<tt>opt</tt>' to print out the

            
              statistics gathered, use the '<tt>-stats</tt>' option:</p>


              <pre>   $ opt -stats -mypassname &lt; program.bc &gt; /dev/null<br>    ... statistic output ...<br></pre>


              <p> When running <tt>gccas</tt> on a C file from the SPEC benchmark

            
            suite, it gives a report that looks like this:</p>


              <pre>   7646 bytecodewriter  - Number of normal instructions<br>    725 bytecodewriter  - Number of oversized instructions<br> 129996 bytecodewriter  - Number of bytecode bytes written<br>   2817 raise           - Number of insts DCEd or constprop'd<br>   3213 raise           - Number of cast-of-self removed<br>   5046 raise           - Number of expression trees converted<br>     75 raise           - Number of other getelementptr's formed<br>    138 raise           - Number of load/store peepholes<br>     42 deadtypeelim    - Number of unused typenames removed from symtab<br>    392 funcresolve     - Number of varargs functions resolved<br>     27 globaldce       - Number of global variables removed<br>      2 adce            - Number of basic blocks removed<br>    134 cee             - Number of branches revectored<br>     49 cee             - Number of setcc instruction eliminated<br>    532 gcse            - Number of loads removed<br>   2919 gcse            - Number of instructions removed<br>     86 indvars         - Number of canonical indvars added<br>     87 indvars         - Number of aux indvars removed<br>     25 instcombine     - Number of dead inst eliminate<br>    434 instcombine     - Number of insts combined<br>    248 licm            - Number of load insts hoisted<br>   1298 licm            - Number of insts hoisted to a loop pre-header<br>      3 licm            - Number of insts hoisted to multiple loop preds (bad, no loop pre-header)<br>     75 mem2reg         - Number of alloca's promoted<br>   1444 cfgsimplify     - Number of blocks simplified<br></pre>


            <p>Obviously, with so many optimizations, having a unified framework for this

            
            stuff is very nice.  Making your pass fit well into the framework makes it more

            
            maintainable and useful.</p>


            </div>


            <!-- *********************************************************************** -->

            
            <div class="doc_section">

            
              <a name="common">Helpful Hints for Common Operations</a>

            
            </div>

            
            <!-- *********************************************************************** -->


            <div class="doc_text">


            <p>This section describes how to perform some very simple transformations of

            
            LLVM code.  This is meant to give examples of common idioms used, showing the

            
            practical side of LLVM transformations.  <p> Because this is a "how-to" section,

            
            you should also read about the main classes that you will be working with.  The

            
            <a href="#coreclasses">Core LLVM Class Hierarchy Reference</a> contains details

            
            and descriptions of the main classes that you should know about.</p>


            </div>


            <!-- NOTE: this section should be heavy on example code -->

            
            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="inspection">Basic Inspection and Traversal Routines</a>

            
            </div>


            <div class="doc_text">


            <p>The LLVM compiler infrastructure have many different data structures that may

            
            be traversed.  Following the example of the C++ standard template library, the

            
            techniques used to traverse these various data structures are all basically the

            
            same.  For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or

            
            method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt>

            
            function returns an iterator pointing to one past the last valid element of the

            
            sequence, and there is some <tt>XXXiterator</tt> data type that is common

            
            between the two operations.</p>


            <p>Because the pattern for iteration is common across many different aspects of

            
            the program representation, the standard template library algorithms may be used

            
            on them, and it is easier to remember how to iterate. First we show a few common

            
            examples of the data structures that need to be traversed.  Other data

            
            structures are traversed in very similar ways.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="iterate_function">Iterating over the </a><a

            
              href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a

            
              href="#Function"><tt>Function</tt></a>

            
            </div>


            <div class="doc_text">


            <p>It's quite common to have a <tt>Function</tt> instance that you'd like to

            
            transform in some way; in particular, you'd like to manipulate its

            
            <tt>BasicBlock</tt>s.  To facilitate this, you'll need to iterate over all of

            
            the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>. The following is

            
            an example that prints the name of a <tt>BasicBlock</tt> and the number of

            
            <tt>Instruction</tt>s it contains:</p>


              <pre>  // func is a pointer to a Function instance<br>  for (Function::iterator i = func-&gt;begin(), e = func-&gt;end(); i != e; ++i) {<br><br>      // print out the name of the basic block if it has one, and then the<br>      // number of instructions that it contains<br><br>      cerr &lt;&lt; "Basic block (name=" &lt;&lt; i-&gt;getName() &lt;&lt; ") has " <br>           &lt;&lt; i-&gt;size() &lt;&lt; " instructions.\n";<br>  }<br></pre>


            <p>Note that i can be used as if it were a pointer for the purposes of

            
            invoking member functions of the <tt>Instruction</tt> class.  This is

            
            because the indirection operator is overloaded for the iterator

            
            classes.  In the above code, the expression <tt>i-&gt;size()</tt> is

            
            exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="iterate_basicblock">Iterating over the </a><a

            
              href="#Instruction"><tt>Instruction</tt></a>s in a <a

            
              href="#BasicBlock"><tt>BasicBlock</tt></a>

            
            </div>


            <div class="doc_text">


            <p>Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, it's

            
            easy to iterate over the individual instructions that make up

            
            <tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in

            
            a <tt>BasicBlock</tt>:</p>


              <pre>  // blk is a pointer to a BasicBlock instance<br>  for (BasicBlock::iterator i = blk-&gt;begin(), e = blk-&gt;end(); i != e; ++i)<br>     // the next statement works since operator&lt;&lt;(ostream&amp;,...) <br>     // is overloaded for Instruction&amp;<br>     cerr &lt;&lt; *i &lt;&lt; "\n";<br></pre>


            <p>However, this isn't really the best way to print out the contents of a

            
            <tt>BasicBlock</tt>!  Since the ostream operators are overloaded for virtually

            
            anything you'll care about, you could have just invoked the print routine on the

            
            basic block itself: <tt>cerr &lt;&lt; *blk &lt;&lt; "\n";</tt>.</p>


            <p>Note that currently operator&lt;&lt; is implemented for <tt>Value*</tt>, so

            
            it will print out the contents of the pointer, instead of the pointer value you

            
            might expect.  This is a deprecated interface that will be removed in the

            
            future, so it's best not to depend on it.  To print out the pointer value for

            
            now, you must cast to <tt>void*</tt>.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="iterate_institer">Iterating over the </a><a

            
              href="#Instruction"><tt>Instruction</tt></a>s in a <a

            
              href="#Function"><tt>Function</tt></a>

            
            </div>


            <div class="doc_text">


            <p>If you're finding that you commonly iterate over a <tt>Function</tt>'s

            
            <tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s <tt>Instruction</tt>s,

            
            <tt>InstIterator</tt> should be used instead. You'll need to include <a

            
            href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>,

            
            and then instantiate <tt>InstIterator</tt>s explicitly in your code.  Here's a

            
            small example that shows how to dump all instructions in a function to the standard error stream:<p>


              <pre>#include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"<br>...<br>// Suppose F is a ptr to a function<br>for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)<br>  cerr &lt;&lt; *i &lt;&lt; "\n";<br></pre>

            
            Easy, isn't it?  You can also use <tt>InstIterator</tt>s to fill a

            
            worklist with its initial contents.  For example, if you wanted to

            
            initialize a worklist to contain all instructions in a <tt>Function</tt>

            
            F, all you would need to do is something like:

            
              <pre>std::set&lt;Instruction*&gt; worklist;<br>worklist.insert(inst_begin(F), inst_end(F));<br></pre>


            <p>The STL set <tt>worklist</tt> would now contain all instructions in the

            
            <tt>Function</tt> pointed to by F.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="iterate_convert">Turning an iterator into a class pointer (and

            
              vice-versa)</a>

            
            </div>


            <div class="doc_text">


            <p>Sometimes, it'll be useful to grab a reference (or pointer) to a class

            
            instance when all you've got at hand is an iterator.  Well, extracting

            
            a reference or a pointer from an iterator is very straight-forward.

            
            Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and <tt>j</tt>

            
            is a <tt>BasicBlock::const_iterator</tt>:</p>


              <pre>    Instruction&amp; inst = *i;   // grab reference to instruction reference<br>    Instruction* pinst = &amp;*i; // grab pointer to instruction reference<br>    const Instruction&amp; inst = *j;<br></pre>


            <p>However, the iterators you'll be working with in the LLVM framework are

            
            special: they will automatically convert to a ptr-to-instance type whenever they

            
            need to.  Instead of dereferencing the iterator and then taking the address of

            
            the result, you can simply assign the iterator to the proper pointer type and

            
            you get the dereference and address-of operation as a result of the assignment

            
            (behind the scenes, this is a result of overloading casting mechanisms).  Thus

            
            the last line of the last example,</p>


              <pre>Instruction* pinst = &amp;*i;</pre>


            <p>is semantically equivalent to</p>


              <pre>Instruction* pinst = i;</pre>


            <p>It's also possible to turn a class pointer into the corresponding iterator,

            
            and this is a constant time operation (very efficient).  The following code

            
            snippet illustrates use of the conversion constructors provided by LLVM

            
            iterators.  By using these, you can explicitly grab the iterator of something

            
            without actually obtaining it via iteration over some structure:</p>


              <pre>void printNextInstruction(Instruction* inst) {<br>    BasicBlock::iterator it(inst);<br>    ++it; // after this line, it refers to the instruction after *inst.<br>    if (it != inst-&gt;getParent()-&gt;end()) cerr &lt;&lt; *it &lt;&lt; "\n";<br>}<br></pre>


            </div>


            <!--_______________________________________________________________________-->

            
            <div class="doc_subsubsection">

            
              <a name="iterate_complex">Finding call sites: a slightly more complex

            
              example</a>

            
            </div>


            <div class="doc_text">


            <p>Say that you're writing a FunctionPass and would like to count all the

            
            locations in the entire module (that is, across every <tt>Function</tt>) where a

            
            certain function (i.e., some <tt>Function</tt>*) is already in scope.  As you'll

            
            learn later, you may want to use an <tt>InstVisitor</tt> to accomplish this in a

            
            much more straight-forward manner, but this example will allow us to explore how

            
            you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this

            
            is what we want to do:</p>


              <pre>initialize callCounter to zero<br>for each Function f in the Module<br>    for each BasicBlock b in f<br>      for each Instruction i in b<br>        if (i is a CallInst and calls the given function)<br>          increment callCounter<br></pre>


            <p>And the actual code is (remember, since we're writing a

            
            <tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply has to

            
            override the <tt>runOnFunction</tt> method...):</p>


              <pre>Function* targetFunc = ...;<br><br>class OurFunctionPass : public FunctionPass {<br>  public:<br>    OurFunctionPass(): callCounter(0) { }<br><br>    virtual runOnFunction(Function&amp; F) {<br> 	for (Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {<br> 	    for (BasicBlock::iterator i = b-&gt;begin(); ie = b-&gt;end(); i != ie; ++i) {<br> 		if (<a

            
             href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a>&lt;<a

            
             href="#CallInst">CallInst</a>&gt;(&amp;*i)) {<br> 		    // we know we've encountered a call instruction, so we<br> 		    // need to determine if it's a call to the<br>	            // function pointed to by m_func or not.<br>  <br> 		    if (callInst-&gt;getCalledFunction() == targetFunc)<br> 			++callCounter;<br> 	    }<br> 	}<br>    }<br>    <br>  private:<br>    unsigned  callCounter;<br>};<br></pre>


            </div>


            <!--_______________________________________________________________________-->

            
            <div class="doc_subsubsection">

            
              <a name="calls_and_invokes">Treating calls and invokes the same way</a>

            
            </div>


            <div class="doc_text">


            <p>You may have noticed that the previous example was a bit oversimplified in

            
            that it did not deal with call sites generated by 'invoke' instructions. In

            
            this, and in other situations, you may find that you want to treat

            
            <tt>CallInst</tt>s and <tt>InvokeInst</tt>s the same way, even though their

            
            most-specific common base class is <tt>Instruction</tt>, which includes lots of

            
            less closely-related things. For these cases, LLVM provides a handy wrapper

            
            class called <a

            
            href="http://llvm.cs.uiuc.edu/doxygen/classllvm_1_1CallSite.html"><tt>CallSite</tt></a>.

            
            It is essentially a wrapper around an <tt>Instruction</tt> pointer, with some

            
            methods that provide functionality common to <tt>CallInst</tt>s and

            
            <tt>InvokeInst</tt>s.</p>


            <p>This class has "value semantics": it should be passed by value, not by

            
            reference and it should not be dynamically allocated or deallocated using

            
            <tt>operator new</tt> or <tt>operator delete</tt>. It is efficiently copyable,

            
            assignable and constructable, with costs equivalents to that of a bare pointer.

            
            If you look at its definition, it has only a single pointer member.</p>


            </div>


            <!--_______________________________________________________________________-->

            
            <div class="doc_subsubsection">

            
              <a name="iterate_chains">Iterating over def-use &amp; use-def chains</a>

            
            </div>


            <div class="doc_text">


            <p>Frequently, we might have an instance of the <a

            
            href="/doxygen/structllvm_1_1Value.html">Value Class</a> and we want to

            
            determine which <tt>User</tt>s use the <tt>Value</tt>.  The list of all

            
            <tt>User</tt>s of a particular <tt>Value</tt> is called a <i>def-use</i> chain.

            
            For example, let's say we have a <tt>Function*</tt> named <tt>F</tt> to a

            
            particular function <tt>foo</tt>. Finding all of the instructions that

            
            <i>use</i> <tt>foo</tt> is as simple as iterating over the <i>def-use</i> chain

            
            of <tt>F</tt>:</p>


              <pre>Function* F = ...;<br><br>for (Value::use_iterator i = F-&gt;use_begin(), e = F-&gt;use_end(); i != e; ++i) {<br>    if (Instruction *Inst = dyn_cast&lt;Instruction&gt;(*i)) {<br>        cerr &lt;&lt; "F is used in instruction:\n";<br>        cerr &lt;&lt; *Inst &lt;&lt; "\n";<br>    }<br>}<br></pre>


            <p>Alternately, it's common to have an instance of the <a

            
            href="/doxygen/classllvm_1_1User.html">User Class</a> and need to know what

            
            <tt>Value</tt>s are used by it.  The list of all <tt>Value</tt>s used by a

            
            <tt>User</tt> is known as a <i>use-def</i> chain.  Instances of class

            
            <tt>Instruction</tt> are common <tt>User</tt>s, so we might want to iterate over

            
            all of the values that a particular instruction uses (that is, the operands of

            
            the particular <tt>Instruction</tt>):</p>


              <pre>Instruction* pi = ...;<br><br>for (User::op_iterator i = pi-&gt;op_begin(), e = pi-&gt;op_end(); i != e; ++i) {<br>    Value* v = *i;<br>    ...<br>}<br></pre>


            <!--

            
              def-use chains ("finding all users of"): Value::use_begin/use_end

            
              use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]

            
            -->


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="simplechanges">Making simple changes</a>

            
            </div>


            <div class="doc_text">


            <p>There are some primitive transformation operations present in the LLVM

            
            infrastructure that are worth knowing about.  When performing

            
            transformations, it's fairly common to manipulate the contents of basic

            
            blocks. This section describes some of the common methods for doing so

            
            and gives example code.</p>


            </div>


            <!--_______________________________________________________________________-->

            
            <div class="doc_subsubsection">

            
              <a name="schanges_creating">Creating and inserting new

            
              <tt>Instruction</tt>s</a>

            
            </div>


            <div class="doc_text">


            <p><i>Instantiating Instructions</i></p>


            <p>Creation of <tt>Instruction</tt>s is straight-forward: simply call the

            
            constructor for the kind of instruction to instantiate and provide the necessary

            
            parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> a

            
            (const-ptr-to) <tt>Type</tt>. Thus:</p>


            <pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre>


            <p>will create an <tt>AllocaInst</tt> instance that represents the allocation of

            
            one integer in the current stack frame, at runtime. Each <tt>Instruction</tt>

            
            subclass is likely to have varying default parameters which change the semantics

            
            of the instruction, so refer to the <a

            
            href="/doxygen/classllvm_1_1Instruction.html">doxygen documentation for the subclass of

            
            Instruction</a> that you're interested in instantiating.</p>


            <p><i>Naming values</i></p>


            <p>It is very useful to name the values of instructions when you're able to, as

            
            this facilitates the debugging of your transformations.  If you end up looking

            
            at generated LLVM machine code, you definitely want to have logical names

            
            associated with the results of instructions!  By supplying a value for the

            
            <tt>Name</tt> (default) parameter of the <tt>Instruction</tt> constructor, you

            
            associate a logical name with the result of the instruction's execution at

            
            runtime.  For example, say that I'm writing a transformation that dynamically

            
            allocates space for an integer on the stack, and that integer is going to be

            
            used as some kind of index by some other code.  To accomplish this, I place an

            
            <tt>AllocaInst</tt> at the first point in the first <tt>BasicBlock</tt> of some

            
            <tt>Function</tt>, and I'm intending to use it within the same

            
            <tt>Function</tt>. I might do:</p>


              <pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre>


            <p>where <tt>indexLoc</tt> is now the logical name of the instruction's

            
            execution value, which is a pointer to an integer on the runtime stack.</p>


            <p><i>Inserting instructions</i></p>


            <p>There are essentially two ways to insert an <tt>Instruction</tt>

            
            into an existing sequence of instructions that form a <tt>BasicBlock</tt>:</p>


            <ul>

            
              <li>Insertion into an explicit instruction list


                <p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> within that

            
                <tt>BasicBlock</tt>, and a newly-created instruction we wish to insert

            
                before <tt>*pi</tt>, we do the following: </p>


                  <pre>  BasicBlock *pb = ...;<br>  Instruction *pi = ...;<br>  Instruction *newInst = new Instruction(...);<br>  pb-&gt;getInstList().insert(pi, newInst); // inserts newInst before pi in pb<br></pre>


                <p>Appending to the end of a <tt>BasicBlock</tt> is so common that

            
                the <tt>Instruction</tt> class and <tt>Instruction</tt>-derived

            
                classes provide constructors which take a pointer to a

            
                <tt>BasicBlock</tt> to be appended to. For example code that

            
                looked like: </p>


                  <pre>  BasicBlock *pb = ...;<br>  Instruction *newInst = new Instruction(...);<br>  pb-&gt;getInstList().push_back(newInst); // appends newInst to pb<br></pre>


                <p>becomes: </p>


                  <pre>  BasicBlock *pb = ...;<br>  Instruction *newInst = new Instruction(..., pb);<br></pre>


                <p>which is much cleaner, especially if you are creating

            
                long instruction streams.</p></li>


              <li>Insertion into an implicit instruction list


                <p><tt>Instruction</tt> instances that are already in <tt>BasicBlock</tt>s

            
                are implicitly associated with an existing instruction list: the instruction

            
                list of the enclosing basic block. Thus, we could have accomplished the same

            
                thing as the above code without being given a <tt>BasicBlock</tt> by doing:

            
                </p>


                  <pre>  Instruction *pi = ...;<br>  Instruction *newInst = new Instruction(...);<br>  pi-&gt;getParent()-&gt;getInstList().insert(pi, newInst);<br></pre>


                <p>In fact, this sequence of steps occurs so frequently that the

            
                <tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes provide

            
                constructors which take (as a default parameter) a pointer to an

            
                <tt>Instruction</tt> which the newly-created <tt>Instruction</tt> should

            
                precede.  That is, <tt>Instruction</tt> constructors are capable of

            
                inserting the newly-created instance into the <tt>BasicBlock</tt> of a

            
                provided instruction, immediately before that instruction.  Using an

            
                <tt>Instruction</tt> constructor with a <tt>insertBefore</tt> (default)

            
                parameter, the above code becomes:</p>


                  <pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre>


                <p>which is much cleaner, especially if you're creating a lot of

            
            instructions and adding them to <tt>BasicBlock</tt>s.</p></li>

            
            </ul>


            </div>


            <!--_______________________________________________________________________-->

            
            <div class="doc_subsubsection">

            
              <a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a>

            
            </div>


            <div class="doc_text">


            <p>Deleting an instruction from an existing sequence of instructions that form a

            
            <a href="#BasicBlock"><tt>BasicBlock</tt></a> is very straight-forward. First,

            
            you must have a pointer to the instruction that you wish to delete.  Second, you

            
            need to obtain the pointer to that instruction's basic block. You use the

            
            pointer to the basic block to get its list of instructions and then use the

            
            erase function to remove your instruction. For example:</p>


              <pre>  <a href="#Instruction">Instruction</a> *I = .. ;<br>  <a

            
             href="#BasicBlock">BasicBlock</a> *BB = I-&gt;getParent();<br>  BB-&gt;getInstList().erase(I);<br></pre>


            </div>


            <!--_______________________________________________________________________-->

            
            <div class="doc_subsubsection">

            
              <a name="schanges_replacing">Replacing an <tt>Instruction</tt> with another

            
              <tt>Value</tt></a>

            
            </div>


            <div class="doc_text">


            <p><i>Replacing individual instructions</i></p>


            <p>Including "<a href="/doxygen/BasicBlockUtils_8h-source.html">llvm/Transforms/Utils/BasicBlockUtils.h</a>"

            
            permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt>

            
            and <tt>ReplaceInstWithInst</tt>.</p>


            <h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4>


            <ul>

            
              <li><tt>ReplaceInstWithValue</tt>


                <p>This function replaces all uses (within a basic block) of a given

            
                instruction with a value, and then removes the original instruction. The

            
                following example illustrates the replacement of the result of a particular

            
                <tt>AllocaInst</tt> that allocates memory for a single integer with an null

            
                pointer to an integer.</p>


                  <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace-&gt;getParent()-&gt;getInstList(), ii,<br>                     Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre></li>


              <li><tt>ReplaceInstWithInst</tt>


                <p>This function replaces a particular instruction with another

            
                instruction. The following example illustrates the replacement of one

            
                <tt>AllocaInst</tt> with another.</p>


                  <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithInst(instToReplace-&gt;getParent()-&gt;getInstList(), ii,<br>                    new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt"));<br></pre></li>

            
            </ul>


            <p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p>


            <p>You can use <tt>Value::replaceAllUsesWith</tt> and

            
            <tt>User::replaceUsesOfWith</tt> to change more than one use at a time.  See the

            
            doxygen documentation for the <a href="/doxygen/structllvm_1_1Value.html">Value Class</a>

            
            and <a href="/doxygen/classllvm_1_1User.html">User Class</a>, respectively, for more

            
            information.</p>


            <!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out:

            
            include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with:

            
            ReplaceInstWithValue, ReplaceInstWithInst -->


            </div>


            <!-- *********************************************************************** -->

            
            <div class="doc_section">

            
              <a name="coreclasses">The Core LLVM Class Hierarchy Reference </a>

            
            </div>

            
            <!-- *********************************************************************** -->


            <div class="doc_text">


            <p>The Core LLVM classes are the primary means of representing the program

            
            being inspected or transformed.  The core LLVM classes are defined in

            
            header files in the <tt>include/llvm/</tt> directory, and implemented in

            
            the <tt>lib/VMCore</tt> directory.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Value">The <tt>Value</tt> class</a>

            
            </div>


            <div>


            <p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>

            
            <br>

            
            doxygen info: <a href="/doxygen/structllvm_1_1Value.html">Value Class</a></p>


            <p>The <tt>Value</tt> class is the most important class in the LLVM Source

            
            base.  It represents a typed value that may be used (among other things) as an

            
            operand to an instruction.  There are many different types of <tt>Value</tt>s,

            
            such as <a href="#Constant"><tt>Constant</tt></a>s,<a

            
            href="#Argument"><tt>Argument</tt></a>s. Even <a

            
            href="#Instruction"><tt>Instruction</tt></a>s and <a

            
            href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p>


            <p>A particular <tt>Value</tt> may be used many times in the LLVM representation

            
            for a program.  For example, an incoming argument to a function (represented

            
            with an instance of the <a href="#Argument">Argument</a> class) is "used" by

            
            every instruction in the function that references the argument.  To keep track

            
            of this relationship, the <tt>Value</tt> class keeps a list of all of the <a

            
            href="#User"><tt>User</tt></a>s that is using it (the <a

            
            href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM

            
            graph that can refer to <tt>Value</tt>s).  This use list is how LLVM represents

            
            def-use information in the program, and is accessible through the <tt>use_</tt>*

            
            methods, shown below.</p>


            <p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed,

            
            and this <a href="#Type">Type</a> is available through the <tt>getType()</tt>

            
            method. In addition, all LLVM values can be named.  The "name" of the

            
            <tt>Value</tt> is a symbolic string printed in the LLVM code:</p>


              <pre>   %<b>foo</b> = add int 1, 2<br></pre>


            <p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>

            
            that the name of any value may be missing (an empty string), so names should

            
            <b>ONLY</b> be used for debugging (making the source code easier to read,

            
            debugging printouts), they should not be used to keep track of values or map

            
            between them.  For this purpose, use a <tt>std::map</tt> of pointers to the

            
            <tt>Value</tt> itself instead.</p>


            <p>One important aspect of LLVM is that there is no distinction between an SSA

            
            variable and the operation that produces it.  Because of this, any reference to

            
            the value produced by an instruction (or the value available as an incoming

            
            argument, for example) is represented as a direct pointer to the instance of

            
            the class that

            
            represents this value.  Although this may take some getting used to, it

            
            simplifies the representation and makes it easier to manipulate.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_Value">Important Public Members of the <tt>Value</tt> class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt>Value::use_iterator</tt> - Typedef for iterator over the

            
            use-list<br>

            
                <tt>Value::use_const_iterator</tt> - Typedef for const_iterator over

            
            the use-list<br>

            
                <tt>unsigned use_size()</tt> - Returns the number of users of the

            
            value.<br>

            
                <tt>bool use_empty()</tt> - Returns true if there are no users.<br>

            
                <tt>use_iterator use_begin()</tt> - Get an iterator to the start of

            
            the use-list.<br>

            
                <tt>use_iterator use_end()</tt> - Get an iterator to the end of the

            
            use-list.<br>

            
                <tt><a href="#User">User</a> *use_back()</tt> - Returns the last

            
            element in the list.

            
                <p> These methods are the interface to access the def-use

            
            information in LLVM.  As with all other iterators in LLVM, the naming

            
            conventions follow the conventions defined by the <a href="#stl">STL</a>.</p>

            
              </li>

            
              <li><tt><a href="#Type">Type</a> *getType() const</tt>

            
                <p>This method returns the Type of the Value.</p>

            
              </li>

            
              <li><tt>bool hasName() const</tt><br>

            
                <tt>std::string getName() const</tt><br>

            
                <tt>void setName(const std::string &amp;Name)</tt>

            
                <p> This family of methods is used to access and assign a name to a <tt>Value</tt>,

            
            be aware of the <a href="#nameWarning">precaution above</a>.</p>

            
              </li>

            
              <li><tt>void replaceAllUsesWith(Value *V)</tt>


                <p>This method traverses the use list of a <tt>Value</tt> changing all <a

            
                href="#User"><tt>User</tt>s</a> of the current value to refer to

            
                "<tt>V</tt>" instead.  For example, if you detect that an instruction always

            
                produces a constant value (for example through constant folding), you can

            
                replace all uses of the instruction with the constant like this:</p>


                <pre>  Inst-&gt;replaceAllUsesWith(ConstVal);<br></pre>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="User">The <tt>User</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p>

            
            <tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt><br>

            
            doxygen info: <a href="/doxygen/classllvm_1_1User.html">User Class</a><br>

            
            Superclass: <a href="#Value"><tt>Value</tt></a></p>


            <p>The <tt>User</tt> class is the common base class of all LLVM nodes that may

            
            refer to <a href="#Value"><tt>Value</tt></a>s.  It exposes a list of "Operands"

            
            that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is

            
            referring to.  The <tt>User</tt> class itself is a subclass of

            
            <tt>Value</tt>.</p>


            <p>The operands of a <tt>User</tt> point directly to the LLVM <a

            
            href="#Value"><tt>Value</tt></a> that it refers to.  Because LLVM uses Static

            
            Single Assignment (SSA) form, there can only be one definition referred to,

            
            allowing this direct connection.  This connection provides the use-def

            
            information in LLVM.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_User">Important Public Members of the <tt>User</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p>The <tt>User</tt> class exposes the operand list in two ways: through

            
            an index access interface and through an iterator based interface.</p>


            <ul>

            
              <li><tt>Value *getOperand(unsigned i)</tt><br>

            
                <tt>unsigned getNumOperands()</tt>

            
                <p> These two methods expose the operands of the <tt>User</tt> in a

            
            convenient form for direct access.</p></li>


              <li><tt>User::op_iterator</tt> - Typedef for iterator over the operand

            
            list<br>

            
                <tt>User::op_const_iterator</tt> <tt>use_iterator op_begin()</tt> -

            
            Get an iterator to the start of the operand list.<br>

            
                <tt>use_iterator op_end()</tt> - Get an iterator to the end of the

            
            operand list.

            
                <p> Together, these methods make up the iterator based interface to

            
            the operands of a <tt>User</tt>.</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Instruction">The <tt>Instruction</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p><tt>#include "</tt><tt><a

            
            href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt><br>

            
            doxygen info: <a href="/doxygen/classllvm_1_1Instruction.html">Instruction Class</a><br>

            
            Superclasses: <a href="#User"><tt>User</tt></a>, <a

            
            href="#Value"><tt>Value</tt></a></p>


            <p>The <tt>Instruction</tt> class is the common base class for all LLVM

            
            instructions.  It provides only a few methods, but is a very commonly used

            
            class.  The primary data tracked by the <tt>Instruction</tt> class itself is the

            
            opcode (instruction type) and the parent <a

            
            href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded

            
            into.  To represent a specific type of instruction, one of many subclasses of

            
            <tt>Instruction</tt> are used.</p>


            <p> Because the <tt>Instruction</tt> class subclasses the <a

            
            href="#User"><tt>User</tt></a> class, its operands can be accessed in the same

            
            way as for other <a href="#User"><tt>User</tt></a>s (with the

            
            <tt>getOperand()</tt>/<tt>getNumOperands()</tt> and

            
            <tt>op_begin()</tt>/<tt>op_end()</tt> methods).</p> <p> An important file for

            
            the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> file. This

            
            file contains some meta-data about the various different types of instructions

            
            in LLVM.  It describes the enum values that are used as opcodes (for example

            
            <tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), as well as the

            
            concrete sub-classes of <tt>Instruction</tt> that implement the instruction (for

            
            example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a

            
            href="#SetCondInst">SetCondInst</a></tt>).  Unfortunately, the use of macros in

            
            this file confuses doxygen, so these enum values don't show up correctly in the

            
            <a href="/doxygen/classllvm_1_1Instruction.html">doxygen output</a>.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_Instruction">Important Public Members of the <tt>Instruction</tt>

            
              class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt>

            
                <p>Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that

            
            this  <tt>Instruction</tt> is embedded into.</p></li>

            
              <li><tt>bool mayWriteToMemory()</tt>

            
                <p>Returns true if the instruction writes to memory, i.e. it is a

            
                  <tt>call</tt>,<tt>free</tt>,<tt>invoke</tt>, or <tt>store</tt>.</p></li>

            
              <li><tt>unsigned getOpcode()</tt>

            
                <p>Returns the opcode for the <tt>Instruction</tt>.</p></li>

            
              <li><tt><a href="#Instruction">Instruction</a> *clone() const</tt>

            
                <p>Returns another instance of the specified instruction, identical

            
            in all ways to the original except that the instruction has no parent

            
            (ie it's not embedded into a <a href="#BasicBlock"><tt>BasicBlock</tt></a>),

            
            and it has no name</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="BasicBlock">The <tt>BasicBlock</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p><tt>#include "<a

            
            href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br>

            
            doxygen info: <a href="/doxygen/structllvm_1_1BasicBlock.html">BasicBlock

            
            Class</a><br>

            
            Superclass: <a href="#Value"><tt>Value</tt></a></p>


            <p>This class represents a single entry multiple exit section of the code,

            
            commonly known as a basic block by the compiler community.  The

            
            <tt>BasicBlock</tt> class maintains a list of <a

            
            href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block.

            
            Matching the language definition, the last element of this list of instructions

            
            is always a terminator instruction (a subclass of the <a

            
            href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p>


            <p>In addition to tracking the list of instructions that make up the block, the

            
            <tt>BasicBlock</tt> class also keeps track of the <a

            
            href="#Function"><tt>Function</tt></a> that it is embedded into.</p>


            <p>Note that <tt>BasicBlock</tt>s themselves are <a

            
            href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions

            
            like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type

            
            <tt>label</tt>.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt>

            
              class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt>BasicBlock(const std::string &amp;Name = "", </tt><tt><a

            
             href="#Function">Function</a> *Parent = 0)</tt>

            
                <p>The <tt>BasicBlock</tt> constructor is used to create new basic

            
            blocks for insertion into a function.  The constructor optionally takes

            
            a name for the new block, and a <a href="#Function"><tt>Function</tt></a>

            
            to insert it into.  If the <tt>Parent</tt> parameter is specified, the

            
            new <tt>BasicBlock</tt> is automatically inserted at the end of the

            
            specified <a href="#Function"><tt>Function</tt></a>, if not specified,

            
            the BasicBlock must be manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p>

            
              </li>

            
              <li><tt>BasicBlock::iterator</tt> - Typedef for instruction list

            
            iterator<br>

            
                <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>

            
                <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,<tt>size()</tt>,<tt>empty()</tt>,<tt>rbegin()</tt>,<tt>rend()

            
            - </tt>STL style functions for accessing the instruction list.

            
                <p> These methods and typedefs are forwarding functions that have

            
            the same semantics as the standard library methods of the same names.

            
            These methods expose the underlying instruction list of a basic block in

            
            a way that is easy to manipulate.  To get the full complement of

            
            container operations (including operations to update the list), you must

            
            use the <tt>getInstList()</tt> method.</p></li>

            
              <li><tt>BasicBlock::InstListType &amp;getInstList()</tt>

            
                <p> This method is used to get access to the underlying container

            
            that actually holds the Instructions.  This method must be used when

            
            there isn't a forwarding function in the <tt>BasicBlock</tt> class for

            
            the operation that you would like to perform.  Because there are no

            
            forwarding functions for "updating" operations, you need to use this if

            
            you want to update the contents of a <tt>BasicBlock</tt>.</p></li>

            
              <li><tt><a href="#Function">Function</a> *getParent()</tt>

            
                <p> Returns a pointer to <a href="#Function"><tt>Function</tt></a>

            
            the block is embedded into, or a null pointer if it is homeless.</p></li>

            
              <li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt>

            
                <p> Returns a pointer to the terminator instruction that appears at

            
            the end of the <tt>BasicBlock</tt>.  If there is no terminator

            
            instruction, or if the last instruction in the block is not a

            
            terminator, then a null pointer is returned.</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="GlobalValue">The <tt>GlobalValue</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p><tt>#include "<a

            
            href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br>

            
            doxygen info: <a href="/doxygen/classllvm_1_1GlobalValue.html">GlobalValue

            
            Class</a><br>

            
            Superclasses: <a href="#User"><tt>User</tt></a>, <a

            
            href="#Value"><tt>Value</tt></a></p>


            <p>Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a

            
            href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are

            
            visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.

            
            Because they are visible at global scope, they are also subject to linking with

            
            other globals defined in different translation units.  To control the linking

            
            process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,

            
            <tt>GlobalValue</tt>s know whether they have internal or external linkage, as

            
            defined by the <tt>LinkageTypes</tt> enumeration.</p>


            <p>If a <tt>GlobalValue</tt> has internal linkage (equivalent to being

            
            <tt>static</tt> in C), it is not visible to code outside the current translation

            
            unit, and does not participate in linking.  If it has external linkage, it is

            
            visible to external code, and does participate in linking.  In addition to

            
            linkage information, <tt>GlobalValue</tt>s keep track of which <a

            
            href="#Module"><tt>Module</tt></a> they are currently part of.</p>


            <p>Because <tt>GlobalValue</tt>s are memory objects, they are always referred to

            
            by their <b>address</b>. As such, the <a href="#Type"><tt>Type</tt></a> of a

            
            global is always a pointer to its contents. It is important to remember this

            
            when using the <tt>GetElementPtrInst</tt> instruction because this pointer must

            
            be dereferenced first. For example, if you have a <tt>GlobalVariable</tt> (a

            
            subclass of <tt>GlobalValue)</tt> that is an array of 24 ints, type <tt>[24 x

            
            int]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although

            
            the address of the first element of this array and the value of the

            
            <tt>GlobalVariable</tt> are the same, they have different types. The

            
            <tt>GlobalVariable</tt>'s type is <tt>[24 x int]</tt>. The first element's type

            
            is <tt>int.</tt> Because of this, accessing a global value requires you to

            
            dereference the pointer with <tt>GetElementPtrInst</tt> first, then its elements

            
            can be accessed. This is explained in the <a href="LangRef.html#globalvars">LLVM

            
            Language Reference Manual</a>.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_GlobalValue">Important Public Members of the <tt>GlobalValue</tt>

            
              class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt>bool hasInternalLinkage() const</tt><br>

            
                <tt>bool hasExternalLinkage() const</tt><br>

            
                <tt>void setInternalLinkage(bool HasInternalLinkage)</tt>

            
                <p> These methods manipulate the linkage characteristics of the <tt>GlobalValue</tt>.</p>

            
                <p> </p>

            
              </li>

            
              <li><tt><a href="#Module">Module</a> *getParent()</tt>

            
                <p> This returns the <a href="#Module"><tt>Module</tt></a> that the

            
            GlobalValue is currently embedded into.</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Function">The <tt>Function</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p><tt>#include "<a

            
            href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt><br> doxygen

            
            info: <a href="/doxygen/classllvm_1_1Function.html">Function Class</a><br>

            
            Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a

            
            href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>


            <p>The <tt>Function</tt> class represents a single procedure in LLVM.  It is

            
            actually one of the more complex classes in the LLVM heirarchy because it must

            
            keep track of a large amount of data.  The <tt>Function</tt> class keeps track

            
            of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a

            
            href="#Argument"><tt>Argument</tt></a>s, and a <a

            
            href="#SymbolTable"><tt>SymbolTable</tt></a>.</p>


            <p>The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most

            
            commonly used part of <tt>Function</tt> objects.  The list imposes an implicit

            
            ordering of the blocks in the function, which indicate how the code will be

            
            layed out by the backend.  Additionally, the first <a

            
            href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the

            
            <tt>Function</tt>.  It is not legal in LLVM to explicitly branch to this initial

            
            block.  There are no implicit exit nodes, and in fact there may be multiple exit

            
            nodes from a single <tt>Function</tt>.  If the <a

            
            href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that

            
            the <tt>Function</tt> is actually a function declaration: the actual body of the

            
            function hasn't been linked in yet.</p>


            <p>In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the

            
            <tt>Function</tt> class also keeps track of the list of formal <a

            
            href="#Argument"><tt>Argument</tt></a>s that the function receives.  This

            
            container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>

            
            nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for

            
            the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.</p>


            <p>The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used

            
            LLVM feature that is only used when you have to look up a value by name.  Aside

            
            from that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used

            
            internally to make sure that there are not conflicts between the names of <a

            
            href="#Instruction"><tt>Instruction</tt></a>s, <a

            
            href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a

            
            href="#Argument"><tt>Argument</tt></a>s in the function body.</p>


            <p>Note that <tt>Function</tt> is a <a href="#GlobalValue">GlobalValue</a>

            
            and therefore also a <a href="#Constant">Constant</a>. The value of the function

            
            is its address (after linking) which is guaranteed to be constant.</p>

            
            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_Function">Important Public Members of the <tt>Function</tt>

            
              class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt>Function(const </tt><tt><a href="#FunctionType">FunctionType</a>

            
              *Ty, LinkageTypes Linkage, const std::string &amp;N = "", Module* Parent = 0)</tt>


                <p>Constructor used when you need to create new <tt>Function</tt>s to add

            
                the the program.  The constructor must specify the type of the function to

            
                create and what type of linkage the function should have. The <a

            
                href="#FunctionType"><tt>FunctionType</tt></a> argument

            
                specifies the formal arguments and return value for the function. The same

            
                <a href="#FunctionTypel"><tt>FunctionType</tt></a> value can be used to

            
                create multiple functions. The <tt>Parent</tt> argument specifies the Module

            
                in which the function is defined. If this argument is provided, the function

            
                will automatically be inserted into that module's list of

            
                functions.</p></li>


              <li><tt>bool isExternal()</tt>


                <p>Return whether or not the <tt>Function</tt> has a body defined.  If the

            
                function is "external", it does not have a body, and thus must be resolved

            
                by linking with a function defined in a different translation unit.</p></li>


              <li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>

            
                <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>


                <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,

            
                <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt>


                <p>These are forwarding methods that make it easy to access the contents of

            
                a <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>

            
                list.</p></li>


              <li><tt>Function::BasicBlockListType &amp;getBasicBlockList()</tt>


                <p>Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.  This

            
                is necessary to use when you need to update the list or perform a complex

            
                action that doesn't have a forwarding method.</p></li>


              <li><tt>Function::aiterator</tt> - Typedef for the argument list

            
            iterator<br>

            
                <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>


                <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,

            
                <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt>


                <p>These are forwarding methods that make it easy to access the contents of

            
                a <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a>

            
                list.</p></li>


              <li><tt>Function::ArgumentListType &amp;getArgumentList()</tt>


                <p>Returns the list of <a href="#Argument"><tt>Argument</tt></a>s.  This is

            
                necessary to use when you need to update the list or perform a complex

            
                action that doesn't have a forwarding method.</p></li>


              <li><tt><a href="#BasicBlock">BasicBlock</a> &amp;getEntryBlock()</tt>


                <p>Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the

            
                function.  Because the entry block for the function is always the first

            
                block, this returns the first block of the <tt>Function</tt>.</p></li>


              <li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>

            
                <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt>


                <p>This traverses the <a href="#Type"><tt>Type</tt></a> of the

            
                <tt>Function</tt> and returns the return type of the function, or the <a

            
                href="#FunctionType"><tt>FunctionType</tt></a> of the actual

            
                function.</p></li>


              <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>


                <p> Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>

            
                for this <tt>Function</tt>.</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p><tt>#include "<a

            
            href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt>

            
            <br>

            
            doxygen info: <a href="/doxygen/classllvm_1_1GlobalVariable.html">GlobalVariable

            
            Class</a><br> Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a

            
            href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>


            <p>Global variables are represented with the (suprise suprise)

            
            <tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are also

            
            subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are

            
            always referenced by their address (global values must live in memory, so their

            
            "name" refers to their address). See <a

            
            href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global variables

            
            may have an initial value (which must be a <a

            
            href="#Constant"><tt>Constant</tt></a>), and if they have an initializer, they

            
            may be marked as "constant" themselves (indicating that their contents never

            
            change at runtime).</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_GlobalVariable">Important Public Members of the

            
              <tt>GlobalVariable</tt> class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt>GlobalVariable(const </tt><tt><a href="#Type">Type</a> *Ty, bool

            
              isConstant, LinkageTypes&amp; Linkage, <a href="#Constant">Constant</a>

            
              *Initializer = 0, const std::string &amp;Name = "", Module* Parent = 0)</tt>


                <p>Create a new global variable of the specified type. If

            
                <tt>isConstant</tt> is true then the global variable will be marked as

            
                unchanging for the program. The Linkage parameter specifies the type of

            
                linkage (internal, external, weak, linkonce, appending) for the variable. If

            
                the linkage is InternalLinkage, WeakLinkage, or LinkOnceLinkage,&nbsp; then

            
                the resultant global variable will have internal linkage.  AppendingLinkage

            
                concatenates together all instances (in different translation units) of the

            
                variable into a single variable but is only applicable to arrays.  &nbsp;See

            
                the <a href="LangRef.html#modulestructure">LLVM Language Reference</a> for

            
                further details on linkage types. Optionally an initializer, a name, and the

            
                module to put the variable into may be specified for the global variable as

            
                well.</p></li>


              <li><tt>bool isConstant() const</tt>


                <p>Returns true if this is a global variable that is known not to

            
                be modified at runtime.</p></li>


              <li><tt>bool hasInitializer()</tt>


                <p>Returns true if this <tt>GlobalVariable</tt> has an intializer.</p></li>


              <li><tt><a href="#Constant">Constant</a> *getInitializer()</tt>


                <p>Returns the intial value for a <tt>GlobalVariable</tt>.  It is not legal

            
                to call this method if there is no initializer.</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Module">The <tt>Module</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p><tt>#include "<a

            
            href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt><br> doxygen info:

            
            <a href="/doxygen/classllvm_1_1Module.html">Module Class</a></p>


            <p>The <tt>Module</tt> class represents the top level structure present in LLVM

            
            programs.  An LLVM module is effectively either a translation unit of the

            
            original program or a combination of several translation units merged by the

            
            linker.  The <tt>Module</tt> class keeps track of a list of <a

            
            href="#Function"><tt>Function</tt></a>s, a list of <a

            
            href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a

            
            href="#SymbolTable"><tt>SymbolTable</tt></a>.  Additionally, it contains a few

            
            helpful member functions that try to make common operations easy.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_Module">Important Public Members of the <tt>Module</tt> class</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
              <li><tt>Module::Module(std::string name = "")</tt></li>

            
            </ul>


            <p>Constructing a <a href="#Module">Module</a> is easy. You can optionally

            
            provide a name for it (probably based on the name of the translation unit).</p>


            <ul>

            
              <li><tt>Module::iterator</tt> - Typedef for function list iterator<br>

            
                <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>


                <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,

            
                <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt>


                <p>These are forwarding methods that make it easy to access the contents of

            
                a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>

            
                list.</p></li>


              <li><tt>Module::FunctionListType &amp;getFunctionList()</tt>


                <p> Returns the list of <a href="#Function"><tt>Function</tt></a>s.  This is

            
                necessary to use when you need to update the list or perform a complex

            
                action that doesn't have a forwarding method.</p>


                <p><!--  Global Variable --></p></li>

            
            </ul>


            <hr>


            <ul>

            
              <li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>


                <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>


                <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,

            
                <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt>


                <p> These are forwarding methods that make it easy to access the contents of

            
                a <tt>Module</tt> object's <a

            
                href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li>


              <li><tt>Module::GlobalListType &amp;getGlobalList()</tt>


                <p>Returns the list of <a

            
                href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.  This is necessary to

            
                use when you need to update the list or perform a complex action that

            
                doesn't have a forwarding method.</p>


                <p><!--  Symbol table stuff --> </p></li>

            
            </ul>


            <hr>


            <ul>

            
              <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>


                <p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>

            
                for this <tt>Module</tt>.</p>


                <p><!--  Convenience methods --></p></li>

            
            </ul>


            <hr>


            <ul>

            
              <li><tt><a href="#Function">Function</a> *getFunction(const std::string

            
              &amp;Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt>


                <p>Look up the specified function in the <tt>Module</tt> <a

            
                href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return

            
                <tt>null</tt>.</p></li>


              <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const

            
              std::string &amp;Name, const <a href="#FunctionType">FunctionType</a> *T)</tt>


                <p>Look up the specified function in the <tt>Module</tt> <a

            
                href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an

            
                external declaration for the function and return it.</p></li>


              <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt>


                <p>If there is at least one entry in the <a

            
                href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a

            
                href="#Type"><tt>Type</tt></a>, return it.  Otherwise return the empty

            
                string.</p></li>


              <li><tt>bool addTypeName(const std::string &amp;Name, const <a

            
              href="#Type">Type</a> *Ty)</tt>


                <p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a>

            
                mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this

            
                name, true is returned and the <a

            
                href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Constant">The <tt>Constant</tt> class and subclasses</a>

            
            </div>


            <div class="doc_text">


            <p>Constant represents a base class for different types of constants. It

            
            is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,

            
            ConstantArray etc for representing the various types of Constants.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_Value">Important Public Methods</a>

            
            </div>


            <div class="doc_text">


            <ul>

            
                <hr> Important Subclasses of Constant

            
                <p> </p>

            
                <ul>

            
                  <li>ConstantSInt : This subclass of Constant represents a signed

            
            integer constant.

            
                    <ul>

            
            	<li><tt>int64_t getValue() const</tt>: Returns the underlying value of

            
            this constant. </li>

            
                    </ul>

            
                  </li>

            
                  <li>ConstantUInt : This class represents an unsigned integer.

            
                    <ul>

            
            	<li><tt>uint64_t getValue() const</tt>: Returns the underlying value

            
            of this constant. </li>

            
                    </ul>

            
                  </li>

            
                  <li>ConstantFP : This class represents a floating point constant.

            
                    <ul>

            
            	<li><tt>double getValue() const</tt>: Returns the underlying value of

            
            this constant. </li>

            
                    </ul>

            
                  </li>

            
                  <li>ConstantBool : This represents a boolean constant.

            
                    <ul>

            
            	<li><tt>bool getValue() const</tt>: Returns the underlying value of

            
            this constant. </li>

            
                    </ul>

            
                  </li>

            
                  <li>ConstantArray : This represents a constant array.

            
                    <ul>

            
            	<li><tt>const std::vector&lt;Use&gt; &amp;getValues() const</tt>:

            
            Returns a Vecotr of component constants that makeup this array. </li>

            
                    </ul>

            
                  </li>

            
                  <li>ConstantStruct : This represents a constant struct.

            
                    <ul>

            
            	<li><tt>const std::vector&lt;Use&gt; &amp;getValues() const</tt>:

            
            Returns a Vecotr of component constants that makeup this array. </li>

            
                    </ul>

            
                  </li>

            
                  <li>GlobalValue : This represents either a global variable or a

            
                  function. In either case, the value is a constant fixed address

            
                  (after linking).

            
                  </li>

            
                </ul>

            
              </li>

            
            </ul>

            
            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Type">The <tt>Type</tt> class and Derived Types</a>

            
            </div>


            <div class="doc_text">


            <p>Type as noted earlier is also a subclass of a Value class.  Any primitive

            
            type (like int, short etc) in LLVM is an instance of Type Class.  All other

            
            types are instances of subclasses of type like FunctionType, ArrayType

            
            etc. DerivedType is the interface for all such dervied types including

            
            FunctionType, ArrayType, PointerType, StructType. Types can have names. They can

            
            be recursive (StructType).  There exists exactly one instance of any type

            
            structure at a time. This allows using pointer equality of Type *s for comparing

            
            types.</p>


            </div>


            <!-- _______________________________________________________________________ -->

            
            <div class="doc_subsubsection">

            
              <a name="m_Value">Important Public Methods</a>

            
            </div>


            <div class="doc_text">


            <ul>


              <li><tt>bool isSigned() const</tt>: Returns whether an integral numeric type

            
              is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is

            
              not true for Float and Double. </li>


              <li><tt>bool isUnsigned() const</tt>: Returns whether a numeric type is

            
              unsigned. This is not quite the complement of isSigned... nonnumeric types

            
              return false as they do with isSigned. This returns true for UByteTy,

            
              UShortTy, UIntTy, and ULongTy. </li>


              <li><tt>bool isInteger() const</tt>: Equivalent to isSigned() || isUnsigned().</li>


              <li><tt>bool isIntegral() const</tt>: Returns true if this is an integral

            
              type, which is either Bool type or one of the Integer types.</li>


              <li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two

            
              floating point types.</li>


              <li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if

            
              this type can be converted to 'Ty' without any reinterpretation of bits. For

            
              example, uint to int or one pointer type to another.</li>


            <br>

            
                <p>Derived Types</p>


                <ul>

            
                  <li>SequentialType : This is subclassed by ArrayType and PointerType

            
                    <ul>

            
            	<li><tt>const Type * getElementType() const</tt>: Returns the type of

            
            each of the elements in the sequential type. </li>

            
                    </ul>

            
                  </li>

            
                  <li>ArrayType : This is a subclass of SequentialType and defines

            
            interface for array types.

            
                    <ul>

            
            	<li><tt>unsigned getNumElements() const</tt>: Returns the number of

            
            elements in the array. </li>

            
                    </ul>

            
                  </li>

            
                  <li>PointerType : Subclass of SequentialType for  pointer types. </li>

            
                  <li>StructType : subclass of DerivedTypes for struct types </li>

            
                  <li>FunctionType : subclass of DerivedTypes for function types.

            
                    <ul>

            
            	  <li><tt>bool isVarArg() const</tt>: Returns true if its a vararg

            
                      function</li>

            
                      <li><tt> const Type * getReturnType() const</tt>: Returns the

            
                      return type of the function.</li>

            
                      <li><tt>const Type * getParamType (unsigned i)</tt>: Returns

            
                      the type of the ith parameter.</li>

            
                      <li><tt> const unsigned getNumParams() const</tt>: Returns the

            
                      number of formal parameters.</li>

            
                    </ul>

            
                  </li>

            
                </ul>

            
              </li>

            
            </ul>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="Argument">The <tt>Argument</tt> class</a>

            
            </div>


            <div class="doc_text">


            <p>This subclass of Value defines the interface for incoming formal

            
            arguments to a function. A Function maitanis a list of its formal

            
            arguments. An argument has a pointer to the parent Function.</p>


            </div>


            <!-- ======================================================================= -->

            
            <div class="doc_subsection">

            
              <a name="SymbolTable">The <tt>SymbolTable</tt> class</a>

            
            </div>

            
            <div class="doc_text">

            
            <p>This class provides a symbol table that the

            
            <a href="#Function"><tt>Function</tt></a> and <a href="#Module">

            
            <tt>Module</tt></a> classes use for naming definitions. The symbol table can

            
            provide a name for any <a href="#Value"><tt>Value</tt></a> or

            
            <a href="#Type"><tt>Type</tt></a>.  <tt>SymbolTable</tt> is an abstract data

            
            type. It hides the data it contains and provides access to it through a

            
            controlled interface.</p>


            <p>To use the <tt>SymbolTable</tt> well, you need to understand the

            
            structure of the information it holds. The class contains two

            
            <tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of

            
            <tt>Type*</tt> to maps of name (<tt>std::string</tt>) to <tt>Value*</tt>.

            
            The second, <tt>tmap</tt>, is a map of names to <tt>Type*</tt>. Thus, Values

            
            are stored in two-dimensions and accessed by <tt>Type</tt> and name. Types,

            
            however, are stored in a single dimension and accessed only by name.</p>


            <p>The interface of this class provides three basic types of operations:

            
            <ol>

            
              <li><em>Accessors</em>. Accessors provide read-only access to information

            
              such as finding a value for a name with the

            
              <a href="#SymbolTable_lookup">lookup</a> method.</li>

            
              <li><em>Mutators</em>. Mutators allow the user to add information to the

            
              <tt>SymbolTable</tt> with methods like

            
              <a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>

            
              <li><em>Iterators</em>. Iterators allow the user to traverse the content

            
              of the symbol table in well defined ways, such as the method

            
              <a href="#SymbolTable_type_begin"><tt>type_begin</tt></a>.</li>

            
            </ol>


            <h3>Accessors</h3>

            
            <dl>

            
              <dt><tt>Value* lookup(const Type* Ty, const std::string&amp; name) const</tt>:

            
              </dt>

            
              <dd>The <tt>lookup</tt> method searches the type plane given by the

            
              <tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.

            
              If a suitable <tt>Value</tt> is not found, null is returned.</dd>


              <dt><tt>Type* lookupType( const std::string&amp; name) const</tt>:</dt>

            
              <dd>The <tt>lookupType</tt> method searches through the types for a

            
              <tt>Type</tt> with the provided <tt>name</tt>. If a suitable <tt>Type</tt>

            
              is not found, null is returned.</dd>


              <dt><tt>bool hasTypes() const</tt>:</dt>

            
              <dd>This function returns true if an entry has been made into the type

            
              map.</dd>


              <dt><tt>bool isEmpty() const</tt>:</dt>

            
              <dd>This function returns true if both the value and types maps are

            
              empty</dd>


              <dt><tt>std::string get_name(const Value*) const</tt>:</dt>

            
              <dd>This function returns the name of the Value provided or the empty

            
              string if the Value is not in the symbol table.</dd>


              <dt><tt>std::string get_name(const Type*) const</tt>:</dt>

            
              <dd>This function returns the name of the Type provided or the empty

            
              string if the Type is not in the symbol table.</dd>

            
            </dl>


            <h3>Mutators</h3>

            
            <dl>

            
              <dt><tt>void insert(Value *Val)</tt>:</dt>

            
              <dd>This method adds the provided value to the symbol table.  The Value must

            
              have both a name and a type which are extracted and used to place the value

            
              in the correct type plane under the value's name.</dd>


              <dt><tt>void insert(const std::string&amp; Name, Value *Val)</tt>:</dt>

            
              <dd> Inserts a constant or type into the symbol table with the specified

            
              name. There can be a many to one mapping between names and constants

            
              or types.</dd>


              <dt><tt>void insert(const std::string&amp; Name, Type *Typ)</tt>:</dt>

            
              <dd> Inserts a type into the symbol table with the specified name. There

            
              can be a many-to-one mapping between names and types. This method

            
              allows a type with an existing entry in the symbol table to get

            
              a new name.</dd>


              <dt><tt>void remove(Value* Val)</tt>:</dt>

            
             <dd> This method removes a named value from the symbol table. The

            
              type and name of the Value are extracted from \p N and used to

            
              lookup the Value in the correct type plane. If the Value is

            
              not in the symbol table, this method silently ignores the

            
              request.</dd>


              <dt><tt>void remove(Type* Typ)</tt>:</dt>

            
              <dd> This method removes a named type from the symbol table. The

            
              name of the type is extracted from \P T and used to look up

            
              the Type in the type map. If the Type is not in the symbol

            
              table, this method silently ignores the request.</dd>


              <dt><tt>Value* remove(const std::string&amp; Name, Value *Val)</tt>:</dt>

            
              <dd> Remove a constant or type with the specified name from the

            
              symbol table.</dd>


              <dt><tt>Type* remove(const std::string&amp; Name, Type* T)</tt>:</dt>

            
              <dd> Remove a type with the specified name from the symbol table.

            
              Returns the removed Type.</dd>


              <dt><tt>Value *value_remove(const value_iterator&amp; It)</tt>:</dt>

            
              <dd> Removes a specific value from the symbol table.

            
              Returns the removed value.</dd>


              <dt><tt>bool strip()</tt>:</dt>

            
              <dd> This method will strip the symbol table of its names leaving

            
              the type and values. </dd>


              <dt><tt>void clear()</tt>:</dt>

            
              <dd>Empty the symbol table completely.</dd>

            
            </dl>


            <h3>Iteration</h3>

            
            <p>The following functions describe three types of iterators you can obtain

            
            the beginning or end of the sequence for both const and non-const. It is

            
            important to keep track of the different kinds of iterators. There are

            
            three idioms worth pointing out:</p>

            
            <table class="doc_table">

            
              <tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>

            
              <tr>

            
                <td>Planes Of name/Value maps</td><td>PI</td>

            
                <td><tt><pre>

            
            for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),

            
            PE = ST.plane_end(); PI != PE; ++PI ) {

            
              PI-&gt;first // This is the Type* of the plane

            
              PI-&gt;second // This is the SymbolTable::ValueMap of name/Value pairs

            
                </pre></tt></td>

            
              </tr>

            
              <tr>

            
                <td>All name/Type Pairs</td><td>TI</td>

            
                <td><tt><pre>

            
            for (SymbolTable::type_const_iterator TI = ST.type_begin(),

            
                 TE = ST.type_end(); TI != TE; ++TI )

            
              TI-&gt;first  // This is the name of the type

            
              TI-&gt;second // This is the Type* value associated with the name

            
                </pre></tt></td>

            
              </tr>

            
              <tr>

            
                <td>name/Value pairs in a plane</td><td>VI</td>

            
                <td><tt><pre>

            
            for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),

            
                 VE = ST.value_end(SomeType); VI != VE; ++VI )

            
              VI-&gt;first  // This is the name of the Value

            
              VI-&gt;second // This is the Value* value associated with the name

            
                </pre></tt></td>

            
              </tr>

            
            </table>

            
            <p>Using the recommended iterator names and idioms will help you avoid

            
            making mistakes. Of particular note, make sure that whenever you use

            
            value_begin(SomeType) that you always compare the resulting iterator

            
            with value_end(SomeType) not value_end(SomeOtherType) or else you

            
            will loop infinitely.</p>


            <dl>


              <dt><tt>plane_iterator plane_begin()</tt>:</dt>

            
              <dd>Get an iterator that starts at the beginning of the type planes.

            
              The iterator will iterate over the Type/ValueMap pairs in the

            
              type planes. </dd>


              <dt><tt>plane_const_iterator plane_begin() const</tt>:</dt>

            
              <dd>Get a const_iterator that starts at the beginning of the type

            
              planes.  The iterator will iterate over the Type/ValueMap pairs

            
              in the type planes. </dd>


              <dt><tt>plane_iterator plane_end()</tt>:</dt>

            
              <dd>Get an iterator at the end of the type planes. This serves as

            
              the marker for end of iteration over the type planes.</dd>


              <dt><tt>plane_const_iterator plane_end() const</tt>:</dt>

            
              <dd>Get a const_iterator at the end of the type planes. This serves as

            
              the marker for end of iteration over the type planes.</dd>


              <dt><tt>value_iterator value_begin(const Type *Typ)</tt>:</dt>

            
              <dd>Get an iterator that starts at the beginning of a type plane.

            
              The iterator will iterate over the name/value pairs in the type plane.

            
              Note: The type plane must already exist before using this.</dd>


              <dt><tt>value_const_iterator value_begin(const Type *Typ) const</tt>:</dt>

            
              <dd>Get a const_iterator that starts at the beginning of a type plane.

            
              The iterator will iterate over the name/value pairs in the type plane.

            
              Note: The type plane must already exist before using this.</dd>


              <dt><tt>value_iterator value_end(const Type *Typ)</tt>:</dt>

            
              <dd>Get an iterator to the end of a type plane. This serves as the marker

            
              for end of iteration of the type plane.

            
              Note: The type plane must already exist before using this.</dd>


              <dt><tt>value_const_iterator value_end(const Type *Typ) const</tt>:</dt>

            
              <dd>Get a const_iterator to the end of a type plane. This serves as the

            
              marker for end of iteration of the type plane.

            
              Note: the type plane must already exist before using this.</dd>


              <dt><tt>type_iterator type_begin()</tt>:</dt>

            
              <dd>Get an iterator to the start of the name/Type map.</dd>


              <dt><tt>type_const_iterator type_begin() cons</tt>:</dt>

            
              <dd> Get a const_iterator to the start of the name/Type map.</dd>


              <dt><tt>type_iterator type_end()</tt>:</dt>

            
              <dd>Get an iterator to the end of the name/Type map. This serves as the

            
              marker for end of iteration of the types.</dd>


              <dt><tt>type_const_iterator type_end() const</tt>:</dt>

            
              <dd>Get a const-iterator to the end of the name/Type map. This serves

            
              as the marker for end of iteration of the types.</dd>


              <dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>

            
              <dd>This method returns a plane_const_iterator for iteration over

            
              the type planes starting at a specific plane, given by \p Ty.</dd>


              <dt><tt>plane_iterator find( const Type* Typ </tt>:</dt>

            
              <dd>This method returns a plane_iterator for iteration over the

            
              type planes starting at a specific plane, given by \p Ty.</dd>


              <dt><tt>const ValueMap* findPlane( const Type* Typ ) cons</tt>:</dt>

            
              <dd>This method returns a ValueMap* for a specific type plane. This

            
              interface is deprecated and may go away in the future.</dd>

            
            </dl>

            
            </div>


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              <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and

            
              <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>

            
              <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>

            
              Last modified: $Date$

            
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