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				4	<head>
				5	<title>LLVM Programmer's Manual</title>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	6	<link rel="stylesheet" href="llvm.css" type="text/css">
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Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	8	<body>
				9
				10	<div class="doc_title">
				11	LLVM Programmer's Manual
				12	</div>
				13
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	14	<ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	15	<li><a href="#introduction">Introduction</a></li>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	16	<li><a href="#general">General Information</a>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	17	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	18	<li><a href="#stl">The C++ Standard Template Library</a></li>
				19	<!--
				20	<li>The <tt>-time-passes</tt> option</li>
				21	<li>How to use the LLVM Makefile system</li>
				22	<li>How to write a regression test</li>
Chris Lattner	61db465	2004-12-08 19:05:44 +0000	[diff] [blame]	23
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	24	-->
Chris Lattner	84b7f8d	2003-08-01 22:20:59 +0000	[diff] [blame]	25	</ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	26	</li>
				27	<li><a href="#apis">Important and useful LLVM APIs</a>
				28	<ul>
				29	<li><a href="#isa">The <tt>isa<></tt>, <tt>cast<></tt>
				30	and <tt>dyn_cast<></tt> templates</a> </li>
				31	<li><a href="#DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt>
				32	option</a>
				33	<ul>
				34	<li><a href="#DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt>
				35	and the <tt>-debug-only</tt> option</a> </li>
				36	</ul>
				37	</li>
				38	<li><a href="#Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	39	option</a></li>
				40	<!--
				41	<li>The <tt>InstVisitor</tt> template
				42	<li>The general graph API
				43	-->
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	44	</ul>
				45	</li>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	46	<li><a href="#common">Helpful Hints for Common Operations</a>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	47	<ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	48	<li><a href="#inspection">Basic Inspection and Traversal Routines</a>
				49	<ul>
				50	<li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
				51	in a <tt>Function</tt></a> </li>
				52	<li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
				53	in a <tt>BasicBlock</tt></a> </li>
				54	<li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
				55	in a <tt>Function</tt></a> </li>
				56	<li><a href="#iterate_convert">Turning an iterator into a
				57	class pointer</a> </li>
				58	<li><a href="#iterate_complex">Finding call sites: a more
				59	complex example</a> </li>
				60	<li><a href="#calls_and_invokes">Treating calls and invokes
				61	the same way</a> </li>
				62	<li><a href="#iterate_chains">Iterating over def-use &
				63	use-def chains</a> </li>
				64	</ul>
				65	</li>
				66	<li><a href="#simplechanges">Making simple changes</a>
				67	<ul>
				68	<li><a href="#schanges_creating">Creating and inserting new
				69	<tt>Instruction</tt>s</a> </li>
				70	<li><a href="#schanges_deleting">Deleting <tt>Instruction</tt>s</a> </li>
				71	<li><a href="#schanges_replacing">Replacing an <tt>Instruction</tt>
				72	with another <tt>Value</tt></a> </li>
				73	</ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	74	</li>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	75	<!--
				76	<li>Working with the Control Flow Graph
				77	<ul>
				78	<li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
				79	<li>
				80	<li>
				81	</ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	82	-->
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	83	</ul>
				84	</li>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	85
				86	<li><a href="#advanced">Advanced Topics</a>
				87	<ul>
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	88	<li><a href="#TypeResolve">LLVM Type Resolution</a>
				89	<ul>
				90	<li><a href="#BuildRecType">Basic Recursive Type Construction</a></li>
				91	<li><a href="#refineAbstractTypeTo">The <tt>refineAbstractTypeTo</tt> method</a></li>
				92	<li><a href="#PATypeHolder">The PATypeHolder Class</a></li>
				93	<li><a href="#AbstractTypeUser">The AbstractTypeUser Class</a></li>
				94	</ul></li>
				95
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	96	<li><a href="#SymbolTable">The <tt>SymbolTable</tt> class </a></li>
				97	</ul></li>
				98
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	99	<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	100	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	101	<li><a href="#Value">The <tt>Value</tt> class</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	102	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	103	<li><a href="#User">The <tt>User</tt> class</a>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	104	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	105	<li><a href="#Instruction">The <tt>Instruction</tt> class</a>
				106	<ul>
				107	<li><a href="#GetElementPtrInst">The <tt>GetElementPtrInst</tt> class</a></li>
				108	</ul>
				109	</li>
				110	<li><a href="#Module">The <tt>Module</tt> class</a></li>
				111	<li><a href="#Constant">The <tt>Constant</tt> class</a>
				112	<ul>
				113	<li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
				114	<ul>
				115	<li><a href="#BasicBlock">The <tt>BasicBlock</tt>class</a></li>
				116	<li><a href="#Function">The <tt>Function</tt> class</a></li>
				117	<li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a></li>
				118	</ul>
				119	</li>
				120	</ul>
				121	</li>
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	122	</ul>
				123	</li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	124	<li><a href="#Type">The <tt>Type</tt> class</a> </li>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	125	<li><a href="#Argument">The <tt>Argument</tt> class</a></li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	126	</ul>
				127	</li>
				128	</ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	129	</li>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	130	</ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	131
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	132	<div class="doc_author">
				133	<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
Chris Lattner	94c4359	2004-05-26 16:52:55 +0000	[diff] [blame]	134	<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>,
				135	<a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a>, and
				136	<a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	137	</div>
				138
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	139	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	140	<div class="doc_section">
				141	<a name="introduction">Introduction </a>
				142	</div>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	143	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	144
				145	<div class="doc_text">
				146
				147	<p>This document is meant to highlight some of the important classes and
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	148	interfaces available in the LLVM source-base. This manual is not
				149	intended to explain what LLVM is, how it works, and what LLVM code looks
				150	like. It assumes that you know the basics of LLVM and are interested
				151	in writing transformations or otherwise analyzing or manipulating the
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	152	code.</p>
				153
				154	<p>This document should get you oriented so that you can find your
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	155	way in the continuously growing source code that makes up the LLVM
				156	infrastructure. Note that this manual is not intended to serve as a
				157	replacement for reading the source code, so if you think there should be
				158	a method in one of these classes to do something, but it's not listed,
				159	check the source. Links to the <a href="/doxygen/">doxygen</a> sources
				160	are provided to make this as easy as possible.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	161
				162	<p>The first section of this document describes general information that is
				163	useful to know when working in the LLVM infrastructure, and the second describes
				164	the Core LLVM classes. In the future this manual will be extended with
				165	information describing how to use extension libraries, such as dominator
				166	information, CFG traversal routines, and useful utilities like the <tt><a
				167	href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.</p>
				168
				169	</div>
				170
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	171	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	172	<div class="doc_section">
				173	<a name="general">General Information</a>
				174	</div>
				175	<!-- *********************************************************************** -->
				176
				177	<div class="doc_text">
				178
				179	<p>This section contains general information that is useful if you are working
				180	in the LLVM source-base, but that isn't specific to any particular API.</p>
				181
				182	</div>
				183
				184	<!-- ======================================================================= -->
				185	<div class="doc_subsection">
				186	<a name="stl">The C++ Standard Template Library</a>
				187	</div>
				188
				189	<div class="doc_text">
				190
				191	<p>LLVM makes heavy use of the C++ Standard Template Library (STL),
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	192	perhaps much more than you are used to, or have seen before. Because of
				193	this, you might want to do a little background reading in the
				194	techniques used and capabilities of the library. There are many good
				195	pages that discuss the STL, and several books on the subject that you
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	196	can get, so it will not be discussed in this document.</p>
				197
				198	<p>Here are some useful links:</p>
				199
				200	<ol>
				201
				202	<li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++ Library
				203	reference</a> - an excellent reference for the STL and other parts of the
				204	standard C++ library.</li>
				205
				206	<li><a href="http://www.tempest-sw.com/cpp/">C++ In a Nutshell</a> - This is an
Tanya Lattner	09cf73c	2004-06-22 04:24:55 +0000	[diff] [blame]	207	O'Reilly book in the making. It has a decent
				208	Standard Library
				209	Reference that rivals Dinkumware's, and is unfortunately no longer free since the book has been
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	210	published.</li>
				211
				212	<li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
				213	Questions</a></li>
				214
				215	<li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
				216	Contains a useful <a
				217	href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
				218	STL</a>.</li>
				219
				220	<li><a href="http://www.research.att.com/%7Ebs/C++.html">Bjarne Stroustrup's C++
				221	Page</a></li>
				222
Tanya Lattner	79445ba	2004-12-08 18:34:56 +0000	[diff] [blame]	223	<li><a href="http://64.78.49.204/">
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	224	Bruce Eckel's Thinking in C++, 2nd ed. Volume 2 Revision 4.0 (even better, get
				225	the book).</a></li>
				226
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	227	</ol>
				228
				229	<p>You are also encouraged to take a look at the <a
				230	href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
				231	to write maintainable code more than where to put your curly braces.</p>
				232
				233	</div>
				234
				235	<!-- ======================================================================= -->
				236	<div class="doc_subsection">
				237	<a name="stl">Other useful references</a>
				238	</div>
				239
				240	<div class="doc_text">
				241
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	242	<ol>
				243	<li><a href="http://www.psc.edu/%7Esemke/cvs_branches.html">CVS
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	244	Branch and Tag Primer</a></li>
Misha Brukman	a0f71e4	2004-06-18 18:39:00 +0000	[diff] [blame]	245	<li><a href="http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html">Using
				246	static and shared libraries across platforms</a></li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	247	</ol>
				248
				249	</div>
				250
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	251	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	252	<div class="doc_section">
				253	<a name="apis">Important and useful LLVM APIs</a>
				254	</div>
				255	<!-- *********************************************************************** -->
				256
				257	<div class="doc_text">
				258
				259	<p>Here we highlight some LLVM APIs that are generally useful and good to
				260	know about when writing transformations.</p>
				261
				262	</div>
				263
				264	<!-- ======================================================================= -->
				265	<div class="doc_subsection">
				266	<a name="isa">The isa<>, cast<> and dyn_cast<> templates</a>
				267	</div>
				268
				269	<div class="doc_text">
				270
				271	<p>The LLVM source-base makes extensive use of a custom form of RTTI.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	272	These templates have many similarities to the C++ <tt>dynamic_cast<></tt>
				273	operator, but they don't have some drawbacks (primarily stemming from
				274	the fact that <tt>dynamic_cast<></tt> only works on classes that
				275	have a v-table). Because they are used so often, you must know what they
				276	do and how they work. All of these templates are defined in the <a
Chris Lattner	695b78b	2005-04-26 22:56:16 +0000	[diff] [blame^]	277	href="/doxygen/Casting_8h-source.html"><tt>llvm/Support/Casting.h</tt></a>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	278	file (note that you very rarely have to include this file directly).</p>
				279
				280	<dl>
				281	<dt><tt>isa<></tt>: </dt>
				282
				283	<dd>The <tt>isa<></tt> operator works exactly like the Java
				284	"<tt>instanceof</tt>" operator. It returns true or false depending on whether
				285	a reference or pointer points to an instance of the specified class. This can
				286	be very useful for constraint checking of various sorts (example below).</dd>
				287
				288	<dt><tt>cast<></tt>: </dt>
				289
				290	<dd>The <tt>cast<></tt> operator is a "checked cast" operation. It
				291	converts a pointer or reference from a base class to a derived cast, causing
				292	an assertion failure if it is not really an instance of the right type. This
				293	should be used in cases where you have some information that makes you believe
				294	that something is of the right type. An example of the <tt>isa<></tt>
				295	and <tt>cast<></tt> template is:
				296
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	297	<pre>
				298	static bool isLoopInvariant(const <a href="#Value">Value</a> V, const Loop L) {
				299	if (isa<<a href="#Constant">Constant</a>>(V) \|\| isa<<a href="#Argument">Argument</a>>(V) \|\| isa<<a href="#GlobalValue">GlobalValue</a>>(V))
				300	return true;
				301
Chris Lattner	53f72b3	2005-04-22 04:49:59 +0000	[diff] [blame]	302	<i>// Otherwise, it must be an instruction...</i>
				303	return !L->contains(cast<<a href="#Instruction">Instruction</a>>(V)->getParent());
				304	}
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	305	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	306
				307	<p>Note that you should <b>not</b> use an <tt>isa<></tt> test followed
				308	by a <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt>
				309	operator.</p>
				310
				311	</dd>
				312
				313	<dt><tt>dyn_cast<></tt>:</dt>
				314
				315	<dd>The <tt>dyn_cast<></tt> operator is a "checking cast" operation. It
				316	checks to see if the operand is of the specified type, and if so, returns a
				317	pointer to it (this operator does not work with references). If the operand is
				318	not of the correct type, a null pointer is returned. Thus, this works very
				319	much like the <tt>dynamic_cast</tt> operator in C++, and should be used in the
				320	same circumstances. Typically, the <tt>dyn_cast<></tt> operator is used
				321	in an <tt>if</tt> statement or some other flow control statement like this:
				322
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	323	<pre>
				324	if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a href="#AllocationInst">AllocationInst</a>>(Val)) {
				325	...
				326	}
				327	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	328
				329	<p> This form of the <tt>if</tt> statement effectively combines together a
				330	call to <tt>isa<></tt> and a call to <tt>cast<></tt> into one
				331	statement, which is very convenient.</p>
				332
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	333	<p>Note that the <tt>dyn_cast<></tt> operator, like C++'s
				334	<tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused.
				335	In particular you should not use big chained <tt>if/then/else</tt> blocks to
				336	check for lots of different variants of classes. If you find yourself
				337	wanting to do this, it is much cleaner and more efficient to use the
Chris Lattner	53f72b3	2005-04-22 04:49:59 +0000	[diff] [blame]	338	<tt>InstVisitor</tt> class to dispatch over the instruction type directly.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	339
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	340	</dd>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	341
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	342	<dt><tt>cast_or_null<></tt>: </dt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	343
				344	<dd>The <tt>cast_or_null<></tt> operator works just like the
				345	<tt>cast<></tt> operator, except that it allows for a null pointer as
				346	an argument (which it then propagates). This can sometimes be useful,
				347	allowing you to combine several null checks into one.</dd>
				348
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	349	<dt><tt>dyn_cast_or_null<></tt>: </dt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	350
				351	<dd>The <tt>dyn_cast_or_null<></tt> operator works just like the
				352	<tt>dyn_cast<></tt> operator, except that it allows for a null pointer
				353	as an argument (which it then propagates). This can sometimes be useful,
				354	allowing you to combine several null checks into one.</dd>
				355
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	356	</dl>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	357
				358	<p>These five templates can be used with any classes, whether they have a
				359	v-table or not. To add support for these templates, you simply need to add
				360	<tt>classof</tt> static methods to the class you are interested casting
				361	to. Describing this is currently outside the scope of this document, but there
				362	are lots of examples in the LLVM source base.</p>
				363
				364	</div>
				365
				366	<!-- ======================================================================= -->
				367	<div class="doc_subsection">
				368	<a name="DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> option</a>
				369	</div>
				370
				371	<div class="doc_text">
				372
				373	<p>Often when working on your pass you will put a bunch of debugging printouts
				374	and other code into your pass. After you get it working, you want to remove
				375	it... but you may need it again in the future (to work out new bugs that you run
				376	across).</p>
				377
				378	<p> Naturally, because of this, you don't want to delete the debug printouts,
				379	but you don't want them to always be noisy. A standard compromise is to comment
				380	them out, allowing you to enable them if you need them in the future.</p>
				381
Chris Lattner	695b78b	2005-04-26 22:56:16 +0000	[diff] [blame^]	382	<p>The "<tt><a href="/doxygen/Debug_8h-source.html">llvm/Support/Debug.h</a></tt>"
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	383	file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to
				384	this problem. Basically, you can put arbitrary code into the argument of the
				385	<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other
				386	tool) is run with the '<tt>-debug</tt>' command line argument:</p>
				387
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	388	<pre> ... <br> DEBUG(std::cerr << "I am here!\n");<br> ...<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	389
				390	<p>Then you can run your pass like this:</p>
				391
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	392	<pre> $ opt < a.bc > /dev/null -mypass<br> <no output><br> $ opt < a.bc > /dev/null -mypass -debug<br> I am here!<br> $<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	393
				394	<p>Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you
				395	to not have to create "yet another" command line option for the debug output for
				396	your pass. Note that <tt>DEBUG()</tt> macros are disabled for optimized builds,
				397	so they do not cause a performance impact at all (for the same reason, they
				398	should also not contain side-effects!).</p>
				399
				400	<p>One additional nice thing about the <tt>DEBUG()</tt> macro is that you can
				401	enable or disable it directly in gdb. Just use "<tt>set DebugFlag=0</tt>" or
				402	"<tt>set DebugFlag=1</tt>" from the gdb if the program is running. If the
				403	program hasn't been started yet, you can always just run it with
				404	<tt>-debug</tt>.</p>
				405
				406	</div>
				407
				408	<!-- _______________________________________________________________________ -->
				409	<div class="doc_subsubsection">
				410	<a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE()</tt> and
				411	the <tt>-debug-only</tt> option</a>
				412	</div>
				413
				414	<div class="doc_text">
				415
				416	<p>Sometimes you may find yourself in a situation where enabling <tt>-debug</tt>
				417	just turns on <b>too much</b> information (such as when working on the code
				418	generator). If you want to enable debug information with more fine-grained
				419	control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only
				420	option as follows:</p>
				421
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	422	<pre> ...<br> DEBUG(std::cerr << "No debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE "foo"<br> DEBUG(std::cerr << "'foo' debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE "bar"<br> DEBUG(std::cerr << "'bar' debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE ""<br> DEBUG(std::cerr << "No debug type (2)\n");<br> ...<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	423
				424	<p>Then you can run your pass like this:</p>
				425
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	426	<pre> $ opt < a.bc > /dev/null -mypass<br> <no output><br> $ opt < a.bc > /dev/null -mypass -debug<br> No debug type<br> 'foo' debug type<br> 'bar' debug type<br> No debug type (2)<br> $ opt < a.bc > /dev/null -mypass -debug-only=foo<br> 'foo' debug type<br> $ opt < a.bc > /dev/null -mypass -debug-only=bar<br> 'bar' debug type<br> $<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	427
				428	<p>Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of
				429	a file, to specify the debug type for the entire module (if you do this before
Chris Lattner	695b78b	2005-04-26 22:56:16 +0000	[diff] [blame^]	430	you <tt>#include "llvm/Support/Debug.h"</tt>, you don't have to insert the ugly
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	431	<tt>#undef</tt>'s). Also, you should use names more meaningful than "foo" and
				432	"bar", because there is no system in place to ensure that names do not
				433	conflict. If two different modules use the same string, they will all be turned
				434	on when the name is specified. This allows, for example, all debug information
				435	for instruction scheduling to be enabled with <tt>-debug-type=InstrSched</tt>,
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	436	even if the source lives in multiple files.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	437
				438	</div>
				439
				440	<!-- ======================================================================= -->
				441	<div class="doc_subsection">
				442	<a name="Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt>
				443	option</a>
				444	</div>
				445
				446	<div class="doc_text">
				447
				448	<p>The "<tt><a
Chris Lattner	695b78b	2005-04-26 22:56:16 +0000	[diff] [blame^]	449	href="/doxygen/Statistic_8h-source.html">llvm/ADT/Statistic.h</a></tt>" file
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	450	provides a template named <tt>Statistic</tt> that is used as a unified way to
				451	keep track of what the LLVM compiler is doing and how effective various
				452	optimizations are. It is useful to see what optimizations are contributing to
				453	making a particular program run faster.</p>
				454
				455	<p>Often you may run your pass on some big program, and you're interested to see
				456	how many times it makes a certain transformation. Although you can do this with
				457	hand inspection, or some ad-hoc method, this is a real pain and not very useful
				458	for big programs. Using the <tt>Statistic</tt> template makes it very easy to
				459	keep track of this information, and the calculated information is presented in a
				460	uniform manner with the rest of the passes being executed.</p>
				461
				462	<p>There are many examples of <tt>Statistic</tt> uses, but the basics of using
				463	it are as follows:</p>
				464
				465	<ol>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	466	<li>Define your statistic like this:
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	467	<pre>static Statistic<> NumXForms("mypassname", "The # of times I did stuff");<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	468
				469	<p>The <tt>Statistic</tt> template can emulate just about any data-type,
				470	but if you do not specify a template argument, it defaults to acting like
				471	an unsigned int counter (this is usually what you want).</p></li>
				472
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	473	<li>Whenever you make a transformation, bump the counter:
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	474	<pre> ++NumXForms; // I did stuff<br></pre>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	475	</li>
				476	</ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	477
				478	<p>That's all you have to do. To get '<tt>opt</tt>' to print out the
				479	statistics gathered, use the '<tt>-stats</tt>' option:</p>
				480
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	481	<pre> $ opt -stats -mypassname < program.bc > /dev/null<br> ... statistic output ...<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	482
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	483	<p> When running <tt>gccas</tt> on a C file from the SPEC benchmark
				484	suite, it gives a report that looks like this:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	485
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	486	<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>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	487
				488	<p>Obviously, with so many optimizations, having a unified framework for this
				489	stuff is very nice. Making your pass fit well into the framework makes it more
				490	maintainable and useful.</p>
				491
				492	</div>
				493
				494	<!-- *********************************************************************** -->
				495	<div class="doc_section">
				496	<a name="common">Helpful Hints for Common Operations</a>
				497	</div>
				498	<!-- *********************************************************************** -->
				499
				500	<div class="doc_text">
				501
				502	<p>This section describes how to perform some very simple transformations of
				503	LLVM code. This is meant to give examples of common idioms used, showing the
				504	practical side of LLVM transformations. <p> Because this is a "how-to" section,
				505	you should also read about the main classes that you will be working with. The
				506	<a href="#coreclasses">Core LLVM Class Hierarchy Reference</a> contains details
				507	and descriptions of the main classes that you should know about.</p>
				508
				509	</div>
				510
				511	<!-- NOTE: this section should be heavy on example code -->
				512	<!-- ======================================================================= -->
				513	<div class="doc_subsection">
				514	<a name="inspection">Basic Inspection and Traversal Routines</a>
				515	</div>
				516
				517	<div class="doc_text">
				518
				519	<p>The LLVM compiler infrastructure have many different data structures that may
				520	be traversed. Following the example of the C++ standard template library, the
				521	techniques used to traverse these various data structures are all basically the
				522	same. For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or
				523	method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt>
				524	function returns an iterator pointing to one past the last valid element of the
				525	sequence, and there is some <tt>XXXiterator</tt> data type that is common
				526	between the two operations.</p>
				527
				528	<p>Because the pattern for iteration is common across many different aspects of
				529	the program representation, the standard template library algorithms may be used
				530	on them, and it is easier to remember how to iterate. First we show a few common
				531	examples of the data structures that need to be traversed. Other data
				532	structures are traversed in very similar ways.</p>
				533
				534	</div>
				535
				536	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	537	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	538	<a name="iterate_function">Iterating over the </a><a
				539	href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a
				540	href="#Function"><tt>Function</tt></a>
				541	</div>
				542
				543	<div class="doc_text">
				544
				545	<p>It's quite common to have a <tt>Function</tt> instance that you'd like to
				546	transform in some way; in particular, you'd like to manipulate its
				547	<tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over all of
				548	the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>. The following is
				549	an example that prints the name of a <tt>BasicBlock</tt> and the number of
				550	<tt>Instruction</tt>s it contains:</p>
				551
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	552	<pre> // func is a pointer to a Function instance<br> for (Function::iterator i = func->begin(), e = func->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 << "Basic block (name=" << i->getName() << ") has " <br> << i->size() << " instructions.\n";<br> }<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	553
				554	<p>Note that i can be used as if it were a pointer for the purposes of
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	555	invoking member functions of the <tt>Instruction</tt> class. This is
				556	because the indirection operator is overloaded for the iterator
Chris Lattner	7496ec5	2003-08-05 22:54:23 +0000	[diff] [blame]	557	classes. In the above code, the expression <tt>i->size()</tt> is
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	558	exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.</p>
				559
				560	</div>
				561
				562	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	563	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	564	<a name="iterate_basicblock">Iterating over the </a><a
				565	href="#Instruction"><tt>Instruction</tt></a>s in a <a
				566	href="#BasicBlock"><tt>BasicBlock</tt></a>
				567	</div>
				568
				569	<div class="doc_text">
				570
				571	<p>Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, it's
				572	easy to iterate over the individual instructions that make up
				573	<tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in
				574	a <tt>BasicBlock</tt>:</p>
				575
Chris Lattner	55c0461	2005-03-06 06:00:13 +0000	[diff] [blame]	576	<pre>
				577	// blk is a pointer to a BasicBlock instance
				578	for (BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)
				579	// the next statement works since operator<<(ostream&,...)
				580	// is overloaded for Instruction&
				581	std::cerr << *i << "\n";
				582	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	583
				584	<p>However, this isn't really the best way to print out the contents of a
				585	<tt>BasicBlock</tt>! Since the ostream operators are overloaded for virtually
				586	anything you'll care about, you could have just invoked the print routine on the
Chris Lattner	55c0461	2005-03-06 06:00:13 +0000	[diff] [blame]	587	basic block itself: <tt>std::cerr << *blk << "\n";</tt>.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	588
				589	</div>
				590
				591	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	592	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	593	<a name="iterate_institer">Iterating over the </a><a
				594	href="#Instruction"><tt>Instruction</tt></a>s in a <a
				595	href="#Function"><tt>Function</tt></a>
				596	</div>
				597
				598	<div class="doc_text">
				599
				600	<p>If you're finding that you commonly iterate over a <tt>Function</tt>'s
				601	<tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s <tt>Instruction</tt>s,
				602	<tt>InstIterator</tt> should be used instead. You'll need to include <a
				603	href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>,
				604	and then instantiate <tt>InstIterator</tt>s explicitly in your code. Here's a
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	605	small example that shows how to dump all instructions in a function to the standard error stream:<p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	606
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	607	<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 << *i << "\n";<br></pre>
Joel Stanley	e7be650	2002-09-09 15:50:33 +0000	[diff] [blame]	608	Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
				609	worklist with its initial contents. For example, if you wanted to
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	610	initialize a worklist to contain all instructions in a <tt>Function</tt>
				611	F, all you would need to do is something like:
				612	<pre>std::set<Instruction*> worklist;<br>worklist.insert(inst_begin(F), inst_end(F));<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	613
				614	<p>The STL set <tt>worklist</tt> would now contain all instructions in the
				615	<tt>Function</tt> pointed to by F.</p>
				616
				617	</div>
				618
				619	<!-- _______________________________________________________________________ -->
				620	<div class="doc_subsubsection">
				621	<a name="iterate_convert">Turning an iterator into a class pointer (and
				622	vice-versa)</a>
				623	</div>
				624
				625	<div class="doc_text">
				626
				627	<p>Sometimes, it'll be useful to grab a reference (or pointer) to a class
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	628	instance when all you've got at hand is an iterator. Well, extracting
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	629	a reference or a pointer from an iterator is very straight-forward.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	630	Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and <tt>j</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	631	is a <tt>BasicBlock::const_iterator</tt>:</p>
				632
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	633	<pre> Instruction& inst = i; // grab reference to instruction reference<br> Instruction pinst = &i; // grab pointer to instruction reference<br> const Instruction& inst = j;<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	634
				635	<p>However, the iterators you'll be working with in the LLVM framework are
				636	special: they will automatically convert to a ptr-to-instance type whenever they
				637	need to. Instead of dereferencing the iterator and then taking the address of
				638	the result, you can simply assign the iterator to the proper pointer type and
				639	you get the dereference and address-of operation as a result of the assignment
				640	(behind the scenes, this is a result of overloading casting mechanisms). Thus
				641	the last line of the last example,</p>
				642
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	643	<pre>Instruction* pinst = &*i;</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	644
				645	<p>is semantically equivalent to</p>
				646
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	647	<pre>Instruction* pinst = i;</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	648
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	649	<p>It's also possible to turn a class pointer into the corresponding iterator,
				650	and this is a constant time operation (very efficient). The following code
				651	snippet illustrates use of the conversion constructors provided by LLVM
				652	iterators. By using these, you can explicitly grab the iterator of something
				653	without actually obtaining it via iteration over some structure:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	654
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	655	<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->getParent()->end()) cerr << it << "\n";<br>}<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	656
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	657	</div>
				658
				659	<!--_______________________________________________________________________-->
				660	<div class="doc_subsubsection">
				661	<a name="iterate_complex">Finding call sites: a slightly more complex
				662	example</a>
				663	</div>
				664
				665	<div class="doc_text">
				666
				667	<p>Say that you're writing a FunctionPass and would like to count all the
				668	locations in the entire module (that is, across every <tt>Function</tt>) where a
				669	certain function (i.e., some <tt>Function</tt>*) is already in scope. As you'll
				670	learn later, you may want to use an <tt>InstVisitor</tt> to accomplish this in a
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	671	much more straight-forward manner, but this example will allow us to explore how
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	672	you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this
				673	is what we want to do:</p>
				674
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	675	<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>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	676
				677	<p>And the actual code is (remember, since we're writing a
				678	<tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply has to
				679	override the <tt>runOnFunction</tt> method...):</p>
				680
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	681	<pre>Function* targetFunc = ...;<br><br>class OurFunctionPass : public FunctionPass {<br> public:<br> OurFunctionPass(): callCounter(0) { }<br><br> virtual runOnFunction(Function& F) {<br> for (Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {<br> for (BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {<br> if (<a
				682	href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a
				683	href="#CallInst">CallInst</a>>(&*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->getCalledFunction() == targetFunc)<br> ++callCounter;<br> }<br> }<br> }<br> <br> private:<br> unsigned callCounter;<br>};<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	684
				685	</div>
				686
Brian Gaeke	f1972c6	2003-11-07 19:25:45 +0000	[diff] [blame]	687	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	688	<div class="doc_subsubsection">
				689	<a name="calls_and_invokes">Treating calls and invokes the same way</a>
				690	</div>
				691
				692	<div class="doc_text">
				693
				694	<p>You may have noticed that the previous example was a bit oversimplified in
				695	that it did not deal with call sites generated by 'invoke' instructions. In
				696	this, and in other situations, you may find that you want to treat
				697	<tt>CallInst</tt>s and <tt>InvokeInst</tt>s the same way, even though their
				698	most-specific common base class is <tt>Instruction</tt>, which includes lots of
				699	less closely-related things. For these cases, LLVM provides a handy wrapper
				700	class called <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	701	href="http://llvm.cs.uiuc.edu/doxygen/classllvm_1_1CallSite.html"><tt>CallSite</tt></a>.
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	702	It is essentially a wrapper around an <tt>Instruction</tt> pointer, with some
				703	methods that provide functionality common to <tt>CallInst</tt>s and
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	704	<tt>InvokeInst</tt>s.</p>
				705
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	706	<p>This class has "value semantics": it should be passed by value, not by
				707	reference and it should not be dynamically allocated or deallocated using
				708	<tt>operator new</tt> or <tt>operator delete</tt>. It is efficiently copyable,
				709	assignable and constructable, with costs equivalents to that of a bare pointer.
				710	If you look at its definition, it has only a single pointer member.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	711
				712	</div>
				713
Chris Lattner	1a3105b	2002-09-09 05:49:39 +0000	[diff] [blame]	714	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	715	<div class="doc_subsubsection">
				716	<a name="iterate_chains">Iterating over def-use & use-def chains</a>
				717	</div>
				718
				719	<div class="doc_text">
				720
				721	<p>Frequently, we might have an instance of the <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	722	href="/doxygen/structllvm_1_1Value.html">Value Class</a> and we want to
				723	determine which <tt>User</tt>s use the <tt>Value</tt>. The list of all
				724	<tt>User</tt>s of a particular <tt>Value</tt> is called a <i>def-use</i> chain.
				725	For example, let's say we have a <tt>Function*</tt> named <tt>F</tt> to a
				726	particular function <tt>foo</tt>. Finding all of the instructions that
				727	<i>use</i> <tt>foo</tt> is as simple as iterating over the <i>def-use</i> chain
				728	of <tt>F</tt>:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	729
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	730	<pre>Function* F = ...;<br><br>for (Value::use_iterator i = F->use_begin(), e = F->use_end(); i != e; ++i) {<br> if (Instruction Inst = dyn_cast<Instruction>(i)) {<br> cerr << "F is used in instruction:\n";<br> cerr << *Inst << "\n";<br> }<br>}<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	731
				732	<p>Alternately, it's common to have an instance of the <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	733	href="/doxygen/classllvm_1_1User.html">User Class</a> and need to know what
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	734	<tt>Value</tt>s are used by it. The list of all <tt>Value</tt>s used by a
				735	<tt>User</tt> is known as a <i>use-def</i> chain. Instances of class
				736	<tt>Instruction</tt> are common <tt>User</tt>s, so we might want to iterate over
				737	all of the values that a particular instruction uses (that is, the operands of
				738	the particular <tt>Instruction</tt>):</p>
				739
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	740	<pre>Instruction* pi = ...;<br><br>for (User::op_iterator i = pi->op_begin(), e = pi->op_end(); i != e; ++i) {<br> Value* v = *i;<br> ...<br>}<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	741
Chris Lattner	1a3105b	2002-09-09 05:49:39 +0000	[diff] [blame]	742	<!--
				743	def-use chains ("finding all users of"): Value::use_begin/use_end
				744	use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	745	-->
				746
				747	</div>
				748
				749	<!-- ======================================================================= -->
				750	<div class="doc_subsection">
				751	<a name="simplechanges">Making simple changes</a>
				752	</div>
				753
				754	<div class="doc_text">
				755
				756	<p>There are some primitive transformation operations present in the LLVM
Joel Stanley	753eb71	2002-09-11 22:32:24 +0000	[diff] [blame]	757	infrastructure that are worth knowing about. When performing
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	758	transformations, it's fairly common to manipulate the contents of basic
				759	blocks. This section describes some of the common methods for doing so
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	760	and gives example code.</p>
				761
				762	</div>
				763
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	764	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	765	<div class="doc_subsubsection">
				766	<a name="schanges_creating">Creating and inserting new
				767	<tt>Instruction</tt>s</a>
				768	</div>
				769
				770	<div class="doc_text">
				771
				772	<p><i>Instantiating Instructions</i></p>
				773
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	774	<p>Creation of <tt>Instruction</tt>s is straight-forward: simply call the
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	775	constructor for the kind of instruction to instantiate and provide the necessary
				776	parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> a
				777	(const-ptr-to) <tt>Type</tt>. Thus:</p>
				778
				779	<pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre>
				780
				781	<p>will create an <tt>AllocaInst</tt> instance that represents the allocation of
				782	one integer in the current stack frame, at runtime. Each <tt>Instruction</tt>
				783	subclass is likely to have varying default parameters which change the semantics
				784	of the instruction, so refer to the <a
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	785	href="/doxygen/classllvm_1_1Instruction.html">doxygen documentation for the subclass of
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	786	Instruction</a> that you're interested in instantiating.</p>
				787
				788	<p><i>Naming values</i></p>
				789
				790	<p>It is very useful to name the values of instructions when you're able to, as
				791	this facilitates the debugging of your transformations. If you end up looking
				792	at generated LLVM machine code, you definitely want to have logical names
				793	associated with the results of instructions! By supplying a value for the
				794	<tt>Name</tt> (default) parameter of the <tt>Instruction</tt> constructor, you
				795	associate a logical name with the result of the instruction's execution at
				796	runtime. For example, say that I'm writing a transformation that dynamically
				797	allocates space for an integer on the stack, and that integer is going to be
				798	used as some kind of index by some other code. To accomplish this, I place an
				799	<tt>AllocaInst</tt> at the first point in the first <tt>BasicBlock</tt> of some
				800	<tt>Function</tt>, and I'm intending to use it within the same
				801	<tt>Function</tt>. I might do:</p>
				802
				803	<pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre>
				804
				805	<p>where <tt>indexLoc</tt> is now the logical name of the instruction's
				806	execution value, which is a pointer to an integer on the runtime stack.</p>
				807
				808	<p><i>Inserting instructions</i></p>
				809
				810	<p>There are essentially two ways to insert an <tt>Instruction</tt>
				811	into an existing sequence of instructions that form a <tt>BasicBlock</tt>:</p>
				812
Joel Stanley	9dd1ad6	2002-09-18 03:17:23 +0000	[diff] [blame]	813	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	814	<li>Insertion into an explicit instruction list
				815
				816	<p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> within that
				817	<tt>BasicBlock</tt>, and a newly-created instruction we wish to insert
				818	before <tt>*pi</tt>, we do the following: </p>
				819
Alkis Evlogimenos	9a5dc4f	2004-05-27 00:57:51 +0000	[diff] [blame]	820	<pre> BasicBlock pb = ...;<br> Instruction pi = ...;<br> Instruction *newInst = new Instruction(...);<br> pb->getInstList().insert(pi, newInst); // inserts newInst before pi in pb<br></pre>
				821
				822	<p>Appending to the end of a <tt>BasicBlock</tt> is so common that
				823	the <tt>Instruction</tt> class and <tt>Instruction</tt>-derived
				824	classes provide constructors which take a pointer to a
				825	<tt>BasicBlock</tt> to be appended to. For example code that
				826	looked like: </p>
				827
				828	<pre> BasicBlock pb = ...;<br> Instruction newInst = new Instruction(...);<br> pb->getInstList().push_back(newInst); // appends newInst to pb<br></pre>
				829
				830	<p>becomes: </p>
				831
				832	<pre> BasicBlock pb = ...;<br> Instruction newInst = new Instruction(..., pb);<br></pre>
				833
				834	<p>which is much cleaner, especially if you are creating
				835	long instruction streams.</p></li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	836
				837	<li>Insertion into an implicit instruction list
				838
				839	<p><tt>Instruction</tt> instances that are already in <tt>BasicBlock</tt>s
				840	are implicitly associated with an existing instruction list: the instruction
				841	list of the enclosing basic block. Thus, we could have accomplished the same
				842	thing as the above code without being given a <tt>BasicBlock</tt> by doing:
				843	</p>
				844
				845	<pre> Instruction pi = ...;<br> Instruction newInst = new Instruction(...);<br> pi->getParent()->getInstList().insert(pi, newInst);<br></pre>
				846
				847	<p>In fact, this sequence of steps occurs so frequently that the
				848	<tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes provide
				849	constructors which take (as a default parameter) a pointer to an
				850	<tt>Instruction</tt> which the newly-created <tt>Instruction</tt> should
				851	precede. That is, <tt>Instruction</tt> constructors are capable of
				852	inserting the newly-created instance into the <tt>BasicBlock</tt> of a
				853	provided instruction, immediately before that instruction. Using an
				854	<tt>Instruction</tt> constructor with a <tt>insertBefore</tt> (default)
				855	parameter, the above code becomes:</p>
				856
				857	<pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre>
				858
				859	<p>which is much cleaner, especially if you're creating a lot of
				860	instructions and adding them to <tt>BasicBlock</tt>s.</p></li>
				861	</ul>
				862
				863	</div>
				864
				865	<!--_______________________________________________________________________-->
				866	<div class="doc_subsubsection">
				867	<a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a>
				868	</div>
				869
				870	<div class="doc_text">
				871
				872	<p>Deleting an instruction from an existing sequence of instructions that form a
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	873	<a href="#BasicBlock"><tt>BasicBlock</tt></a> is very straight-forward. First,
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	874	you must have a pointer to the instruction that you wish to delete. Second, you
				875	need to obtain the pointer to that instruction's basic block. You use the
				876	pointer to the basic block to get its list of instructions and then use the
				877	erase function to remove your instruction. For example:</p>
				878
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	879	<pre> <a href="#Instruction">Instruction</a> *I = .. ;<br> <a
				880	href="#BasicBlock">BasicBlock</a> *BB = I->getParent();<br> BB->getInstList().erase(I);<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	881
				882	</div>
				883
				884	<!--_______________________________________________________________________-->
				885	<div class="doc_subsubsection">
				886	<a name="schanges_replacing">Replacing an <tt>Instruction</tt> with another
				887	<tt>Value</tt></a>
				888	</div>
				889
				890	<div class="doc_text">
				891
				892	<p><i>Replacing individual instructions</i></p>
				893
				894	<p>Including "<a href="/doxygen/BasicBlockUtils_8h-source.html">llvm/Transforms/Utils/BasicBlockUtils.h</a>"
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	895	permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	896	and <tt>ReplaceInstWithInst</tt>.</p>
				897
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	898	<h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	899
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	900	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	901	<li><tt>ReplaceInstWithValue</tt>
				902
				903	<p>This function replaces all uses (within a basic block) of a given
				904	instruction with a value, and then removes the original instruction. The
				905	following example illustrates the replacement of the result of a particular
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	906	<tt>AllocaInst</tt> that allocates memory for a single integer with a null
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	907	pointer to an integer.</p>
				908
				909	<pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,<br> Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre></li>
				910
				911	<li><tt>ReplaceInstWithInst</tt>
				912
				913	<p>This function replaces a particular instruction with another
				914	instruction. The following example illustrates the replacement of one
				915	<tt>AllocaInst</tt> with another.</p>
				916
				917	<pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithInst(instToReplace->getParent()->getInstList(), ii,<br> new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt"));<br></pre></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	918	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	919
				920	<p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p>
				921
				922	<p>You can use <tt>Value::replaceAllUsesWith</tt> and
				923	<tt>User::replaceUsesOfWith</tt> to change more than one use at a time. See the
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	924	doxygen documentation for the <a href="/doxygen/structllvm_1_1Value.html">Value Class</a>
				925	and <a href="/doxygen/classllvm_1_1User.html">User Class</a>, respectively, for more
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	926	information.</p>
				927
				928	<!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out:
				929	include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with:
				930	ReplaceInstWithValue, ReplaceInstWithInst -->
				931
				932	</div>
				933
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	934	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	935	<div class="doc_section">
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	936	<a name="advanced">Advanced Topics</a>
				937	</div>
				938	<!-- *********************************************************************** -->
				939
				940	<div class="doc_text">
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	941	<p>
				942	This section describes some of the advanced or obscure API's that most clients
				943	do not need to be aware of. These API's tend manage the inner workings of the
				944	LLVM system, and only need to be accessed in unusual circumstances.
				945	</p>
				946	</div>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	947
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	948	<!-- ======================================================================= -->
				949	<div class="doc_subsection">
				950	<a name="TypeResolve">LLVM Type Resolution</a>
				951	</div>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	952
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	953	<div class="doc_text">
				954
				955	<p>
				956	The LLVM type system has a very simple goal: allow clients to compare types for
				957	structural equality with a simple pointer comparison (aka a shallow compare).
				958	This goal makes clients much simpler and faster, and is used throughout the LLVM
				959	system.
				960	</p>
				961
				962	<p>
				963	Unfortunately achieving this goal is not a simple matter. In particular,
				964	recursive types and late resolution of opaque types makes the situation very
				965	difficult to handle. Fortunately, for the most part, our implementation makes
				966	most clients able to be completely unaware of the nasty internal details. The
				967	primary case where clients are exposed to the inner workings of it are when
				968	building a recursive type. In addition to this case, the LLVM bytecode reader,
				969	assembly parser, and linker also have to be aware of the inner workings of this
				970	system.
				971	</p>
				972
Chris Lattner	0f876db	2005-04-25 15:47:57 +0000	[diff] [blame]	973	<p>
				974	For our purposes below, we need three concepts. First, an "Opaque Type" is
				975	exactly as defined in the <a href="LangRef.html#t_opaque">language
				976	reference</a>. Second an "Abstract Type" is any type which includes an
				977	opaque type as part of its type graph (for example "<tt>{ opaque, int }</tt>").
				978	Third, a concrete type is a type that is not an abstract type (e.g. "<tt>[ int,
				979	float }</tt>").
				980	</p>
				981
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	982	</div>
				983
				984	<!-- ______________________________________________________________________ -->
				985	<div class="doc_subsubsection">
				986	<a name="BuildRecType">Basic Recursive Type Construction</a>
				987	</div>
				988
				989	<div class="doc_text">
				990
				991	<p>
				992	Because the most common question is "how do I build a recursive type with LLVM",
				993	we answer it now and explain it as we go. Here we include enough to cause this
				994	to be emitted to an output .ll file:
				995	</p>
				996
				997	<pre>
				998	%mylist = type { %mylist*, int }
				999	</pre>
				1000
				1001	<p>
				1002	To build this, use the following LLVM APIs:
				1003	</p>
				1004
				1005	<pre>
				1006	//<i> Create the initial outer struct.</i>
				1007	<a href="#PATypeHolder">PATypeHolder</a> StructTy = OpaqueType::get();
				1008	std::vector<const Type*> Elts;
				1009	Elts.push_back(PointerType::get(StructTy));
				1010	Elts.push_back(Type::IntTy);
				1011	StructType *NewSTy = StructType::get(Elts);
				1012
				1013	//<i> At this point, NewSTy = "{ opaque*, int }". Tell VMCore that</i>
				1014	//<i> the struct and the opaque type are actually the same.</i>
				1015	cast<OpaqueType>(StructTy.get())-><a href="#refineAbstractTypeTo">refineAbstractTypeTo</a>(NewSTy);
				1016
				1017	// <i>NewSTy is potentially invalidated, but StructTy (a <a href="#PATypeHolder">PATypeHolder</a>) is</i>
				1018	// <i>kept up-to-date.</i>
				1019	NewSTy = cast<StructType>(StructTy.get());
				1020
				1021	// <i>Add a name for the type to the module symbol table (optional).</i>
				1022	MyModule->addTypeName("mylist", NewSTy);
				1023	</pre>
				1024
				1025	<p>
				1026	This code shows the basic approach used to build recursive types: build a
				1027	non-recursive type using 'opaque', then use type unification to close the cycle.
				1028	The type unification step is performed by the <tt><a
				1029	ref="#refineAbstractTypeTo">refineAbstractTypeTo</a></tt> method, which is
				1030	described next. After that, we describe the <a
				1031	href="#PATypeHolder">PATypeHolder class</a>.
				1032	</p>
				1033
				1034	</div>
				1035
				1036	<!-- ______________________________________________________________________ -->
				1037	<div class="doc_subsubsection">
				1038	<a name="refineAbstractTypeTo">The <tt>refineAbstractTypeTo</tt> method</a>
				1039	</div>
				1040
				1041	<div class="doc_text">
				1042	<p>
				1043	The <tt>refineAbstractTypeTo</tt> method starts the type unification process.
				1044	While this method is actually a member of the DerivedType class, it is most
				1045	often used on OpaqueType instances. Type unification is actually a recursive
				1046	process. After unification, types can become structurally isomorphic to
				1047	existing types, and all duplicates are deleted (to preserve pointer equality).
				1048	</p>
				1049
				1050	<p>
				1051	In the example above, the OpaqueType object is definitely deleted.
				1052	Additionally, if there is an "{ \2*, int}" type already created in the system,
				1053	the pointer and struct type created are <b>also</b> deleted. Obviously whenever
				1054	a type is deleted, any "Type*" pointers in the program are invalidated. As
				1055	such, it is safest to avoid having <i>any</i> "Type*" pointers to abstract types
				1056	live across a call to <tt>refineAbstractTypeTo</tt> (note that non-abstract
				1057	types can never move or be deleted). To deal with this, the <a
				1058	href="#PATypeHolder">PATypeHolder</a> class is used to maintain a stable
				1059	reference to a possibly refined type, and the <a
				1060	href="#AbstractTypeUser">AbstractTypeUser</a> class is used to update more
				1061	complex datastructures.
				1062	</p>
				1063
				1064	</div>
				1065
				1066	<!-- ______________________________________________________________________ -->
				1067	<div class="doc_subsubsection">
				1068	<a name="PATypeHolder">The PATypeHolder Class</a>
				1069	</div>
				1070
				1071	<div class="doc_text">
				1072	<p>
				1073	PATypeHolder is a form of a "smart pointer" for Type objects. When VMCore
				1074	happily goes about nuking types that become isomorphic to existing types, it
				1075	automatically updates all PATypeHolder objects to point to the new type. In the
				1076	example above, this allows the code to maintain a pointer to the resultant
				1077	resolved recursive type, even though the Type*'s are potentially invalidated.
				1078	</p>
				1079
				1080	<p>
				1081	PATypeHolder is an extremely light-weight object that uses a lazy union-find
				1082	implementation to update pointers. For example the pointer from a Value to its
				1083	Type is maintained by PATypeHolder objects.
				1084	</p>
				1085
				1086	</div>
				1087
				1088	<!-- ______________________________________________________________________ -->
				1089	<div class="doc_subsubsection">
				1090	<a name="AbstractTypeUser">The AbstractTypeUser Class</a>
				1091	</div>
				1092
				1093	<div class="doc_text">
				1094
				1095	<p>
				1096	Some data structures need more to perform more complex updates when types get
				1097	resolved. The <a href="#SymbolTable">SymbolTable</a> class, for example, needs
				1098	move and potentially merge type planes in its representation when a pointer
				1099	changes.</p>
				1100
				1101	<p>
				1102	To support this, a class can derive from the AbstractTypeUser class. This class
				1103	allows it to get callbacks when certain types are resolved. To register to get
				1104	callbacks for a particular type, the DerivedType::{add/remove}AbstractTypeUser
Chris Lattner	0f876db	2005-04-25 15:47:57 +0000	[diff] [blame]	1105	methods can be called on a type. Note that these methods only work for <i>
				1106	abstract</i> types. Concrete types (those that do not include an opaque objects
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	1107	somewhere) can never be refined.
				1108	</p>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	1109	</div>
				1110
				1111
				1112	<!-- ======================================================================= -->
				1113	<div class="doc_subsection">
				1114	<a name="SymbolTable">The <tt>SymbolTable</tt> class</a>
				1115	</div>
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	1116
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	1117	<div class="doc_text">
				1118	<p>This class provides a symbol table that the <a
				1119	href="#Function"><tt>Function</tt></a> and <a href="#Module">
				1120	<tt>Module</tt></a> classes use for naming definitions. The symbol table can
				1121	provide a name for any <a href="#Value"><tt>Value</tt></a> or <a
				1122	href="#Type"><tt>Type</tt></a>. <tt>SymbolTable</tt> is an abstract data
				1123	type. It hides the data it contains and provides access to it through a
				1124	controlled interface.</p>
				1125
				1126	<p>Note that the symbol table class is should not be directly accessed by most
				1127	clients. It should only be used when iteration over the symbol table names
				1128	themselves are required, which is very special purpose. Note that not all LLVM
				1129	<a href="#Value">Value</a>s have names, and those without names (i.e. they have
				1130	an empty name) do not exist in the symbol table.
				1131	</p>
				1132
				1133	<p>To use the <tt>SymbolTable</tt> well, you need to understand the
				1134	structure of the information it holds. The class contains two
				1135	<tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of
				1136	<tt>Type</tt> to maps of name (<tt>std::string</tt>) to <tt>Value</tt>.
				1137	The second, <tt>tmap</tt>, is a map of names to <tt>Type*</tt>. Thus, Values
				1138	are stored in two-dimensions and accessed by <tt>Type</tt> and name. Types,
				1139	however, are stored in a single dimension and accessed only by name.</p>
				1140
				1141	<p>The interface of this class provides three basic types of operations:
				1142	<ol>
				1143	<li><em>Accessors</em>. Accessors provide read-only access to information
				1144	such as finding a value for a name with the
				1145	<a href="#SymbolTable_lookup">lookup</a> method.</li>
				1146	<li><em>Mutators</em>. Mutators allow the user to add information to the
				1147	<tt>SymbolTable</tt> with methods like
				1148	<a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>
				1149	<li><em>Iterators</em>. Iterators allow the user to traverse the content
				1150	of the symbol table in well defined ways, such as the method
				1151	<a href="#SymbolTable_type_begin"><tt>type_begin</tt></a>.</li>
				1152	</ol>
				1153
				1154	<h3>Accessors</h3>
				1155	<dl>
				1156	<dt><tt>Value* lookup(const Type* Ty, const std::string& name) const</tt>:
				1157	</dt>
				1158	<dd>The <tt>lookup</tt> method searches the type plane given by the
				1159	<tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.
				1160	If a suitable <tt>Value</tt> is not found, null is returned.</dd>
				1161
				1162	<dt><tt>Type* lookupType( const std::string& name) const</tt>:</dt>
				1163	<dd>The <tt>lookupType</tt> method searches through the types for a
				1164	<tt>Type</tt> with the provided <tt>name</tt>. If a suitable <tt>Type</tt>
				1165	is not found, null is returned.</dd>
				1166
				1167	<dt><tt>bool hasTypes() const</tt>:</dt>
				1168	<dd>This function returns true if an entry has been made into the type
				1169	map.</dd>
				1170
				1171	<dt><tt>bool isEmpty() const</tt>:</dt>
				1172	<dd>This function returns true if both the value and types maps are
				1173	empty</dd>
				1174	</dl>
				1175
				1176	<h3>Mutators</h3>
				1177	<dl>
				1178	<dt><tt>void insert(Value *Val)</tt>:</dt>
				1179	<dd>This method adds the provided value to the symbol table. The Value must
				1180	have both a name and a type which are extracted and used to place the value
				1181	in the correct type plane under the value's name.</dd>
				1182
				1183	<dt><tt>void insert(const std::string& Name, Value *Val)</tt>:</dt>
				1184	<dd> Inserts a constant or type into the symbol table with the specified
				1185	name. There can be a many to one mapping between names and constants
				1186	or types.</dd>
				1187
				1188	<dt><tt>void insert(const std::string& Name, Type *Typ)</tt>:</dt>
				1189	<dd> Inserts a type into the symbol table with the specified name. There
				1190	can be a many-to-one mapping between names and types. This method
				1191	allows a type with an existing entry in the symbol table to get
				1192	a new name.</dd>
				1193
				1194	<dt><tt>void remove(Value* Val)</tt>:</dt>
				1195	<dd> This method removes a named value from the symbol table. The
				1196	type and name of the Value are extracted from \p N and used to
				1197	lookup the Value in the correct type plane. If the Value is
				1198	not in the symbol table, this method silently ignores the
				1199	request.</dd>
				1200
				1201	<dt><tt>void remove(Type* Typ)</tt>:</dt>
				1202	<dd> This method removes a named type from the symbol table. The
				1203	name of the type is extracted from \P T and used to look up
				1204	the Type in the type map. If the Type is not in the symbol
				1205	table, this method silently ignores the request.</dd>
				1206
				1207	<dt><tt>Value* remove(const std::string& Name, Value *Val)</tt>:</dt>
				1208	<dd> Remove a constant or type with the specified name from the
				1209	symbol table.</dd>
				1210
				1211	<dt><tt>Type* remove(const std::string& Name, Type* T)</tt>:</dt>
				1212	<dd> Remove a type with the specified name from the symbol table.
				1213	Returns the removed Type.</dd>
				1214
				1215	<dt><tt>Value *value_remove(const value_iterator& It)</tt>:</dt>
				1216	<dd> Removes a specific value from the symbol table.
				1217	Returns the removed value.</dd>
				1218
				1219	<dt><tt>bool strip()</tt>:</dt>
				1220	<dd> This method will strip the symbol table of its names leaving
				1221	the type and values. </dd>
				1222
				1223	<dt><tt>void clear()</tt>:</dt>
				1224	<dd>Empty the symbol table completely.</dd>
				1225	</dl>
				1226
				1227	<h3>Iteration</h3>
				1228	<p>The following functions describe three types of iterators you can obtain
				1229	the beginning or end of the sequence for both const and non-const. It is
				1230	important to keep track of the different kinds of iterators. There are
				1231	three idioms worth pointing out:</p>
				1232	<table>
				1233	<tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>
				1234	<tr>
				1235	<td align="left">Planes Of name/Value maps</td><td>PI</td>
				1236	<td align="left"><pre><tt>
				1237	for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),
				1238	PE = ST.plane_end(); PI != PE; ++PI ) {
				1239	PI->first // This is the Type* of the plane
				1240	PI->second // This is the SymbolTable::ValueMap of name/Value pairs
				1241	</tt></pre></td>
				1242	</tr>
				1243	<tr>
				1244	<td align="left">All name/Type Pairs</td><td>TI</td>
				1245	<td align="left"><pre><tt>
				1246	for (SymbolTable::type_const_iterator TI = ST.type_begin(),
				1247	TE = ST.type_end(); TI != TE; ++TI )
				1248	TI->first // This is the name of the type
				1249	TI->second // This is the Type* value associated with the name
				1250	</tt></pre></td>
				1251	</tr>
				1252	<tr>
				1253	<td align="left">name/Value pairs in a plane</td><td>VI</td>
				1254	<td align="left"><pre><tt>
				1255	for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),
				1256	VE = ST.value_end(SomeType); VI != VE; ++VI )
				1257	VI->first // This is the name of the Value
				1258	VI->second // This is the Value* value associated with the name
				1259	</tt></pre></td>
				1260	</tr>
				1261	</table>
				1262
				1263	<p>Using the recommended iterator names and idioms will help you avoid
				1264	making mistakes. Of particular note, make sure that whenever you use
				1265	value_begin(SomeType) that you always compare the resulting iterator
				1266	with value_end(SomeType) not value_end(SomeOtherType) or else you
				1267	will loop infinitely.</p>
				1268
				1269	<dl>
				1270
				1271	<dt><tt>plane_iterator plane_begin()</tt>:</dt>
				1272	<dd>Get an iterator that starts at the beginning of the type planes.
				1273	The iterator will iterate over the Type/ValueMap pairs in the
				1274	type planes. </dd>
				1275
				1276	<dt><tt>plane_const_iterator plane_begin() const</tt>:</dt>
				1277	<dd>Get a const_iterator that starts at the beginning of the type
				1278	planes. The iterator will iterate over the Type/ValueMap pairs
				1279	in the type planes. </dd>
				1280
				1281	<dt><tt>plane_iterator plane_end()</tt>:</dt>
				1282	<dd>Get an iterator at the end of the type planes. This serves as
				1283	the marker for end of iteration over the type planes.</dd>
				1284
				1285	<dt><tt>plane_const_iterator plane_end() const</tt>:</dt>
				1286	<dd>Get a const_iterator at the end of the type planes. This serves as
				1287	the marker for end of iteration over the type planes.</dd>
				1288
				1289	<dt><tt>value_iterator value_begin(const Type *Typ)</tt>:</dt>
				1290	<dd>Get an iterator that starts at the beginning of a type plane.
				1291	The iterator will iterate over the name/value pairs in the type plane.
				1292	Note: The type plane must already exist before using this.</dd>
				1293
				1294	<dt><tt>value_const_iterator value_begin(const Type *Typ) const</tt>:</dt>
				1295	<dd>Get a const_iterator that starts at the beginning of a type plane.
				1296	The iterator will iterate over the name/value pairs in the type plane.
				1297	Note: The type plane must already exist before using this.</dd>
				1298
				1299	<dt><tt>value_iterator value_end(const Type *Typ)</tt>:</dt>
				1300	<dd>Get an iterator to the end of a type plane. This serves as the marker
				1301	for end of iteration of the type plane.
				1302	Note: The type plane must already exist before using this.</dd>
				1303
				1304	<dt><tt>value_const_iterator value_end(const Type *Typ) const</tt>:</dt>
				1305	<dd>Get a const_iterator to the end of a type plane. This serves as the
				1306	marker for end of iteration of the type plane.
				1307	Note: the type plane must already exist before using this.</dd>
				1308
				1309	<dt><tt>type_iterator type_begin()</tt>:</dt>
				1310	<dd>Get an iterator to the start of the name/Type map.</dd>
				1311
				1312	<dt><tt>type_const_iterator type_begin() cons</tt>:</dt>
				1313	<dd> Get a const_iterator to the start of the name/Type map.</dd>
				1314
				1315	<dt><tt>type_iterator type_end()</tt>:</dt>
				1316	<dd>Get an iterator to the end of the name/Type map. This serves as the
				1317	marker for end of iteration of the types.</dd>
				1318
				1319	<dt><tt>type_const_iterator type_end() const</tt>:</dt>
				1320	<dd>Get a const-iterator to the end of the name/Type map. This serves
				1321	as the marker for end of iteration of the types.</dd>
				1322
				1323	<dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>
				1324	<dd>This method returns a plane_const_iterator for iteration over
				1325	the type planes starting at a specific plane, given by \p Ty.</dd>
				1326
				1327	<dt><tt>plane_iterator find( const Type* Typ </tt>:</dt>
				1328	<dd>This method returns a plane_iterator for iteration over the
				1329	type planes starting at a specific plane, given by \p Ty.</dd>
				1330
				1331	</dl>
				1332	</div>
				1333
				1334
				1335
				1336	<!-- *********************************************************************** -->
				1337	<div class="doc_section">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1338	<a name="coreclasses">The Core LLVM Class Hierarchy Reference </a>
				1339	</div>
				1340	<!-- *********************************************************************** -->
				1341
				1342	<div class="doc_text">
				1343
				1344	<p>The Core LLVM classes are the primary means of representing the program
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1345	being inspected or transformed. The core LLVM classes are defined in
				1346	header files in the <tt>include/llvm/</tt> directory, and implemented in
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1347	the <tt>lib/VMCore</tt> directory.</p>
				1348
				1349	</div>
				1350
				1351	<!-- ======================================================================= -->
				1352	<div class="doc_subsection">
				1353	<a name="Value">The <tt>Value</tt> class</a>
				1354	</div>
				1355
				1356	<div>
				1357
				1358	<p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>
				1359	<br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1360	doxygen info: <a href="/doxygen/structllvm_1_1Value.html">Value Class</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1361
				1362	<p>The <tt>Value</tt> class is the most important class in the LLVM Source
				1363	base. It represents a typed value that may be used (among other things) as an
				1364	operand to an instruction. There are many different types of <tt>Value</tt>s,
				1365	such as <a href="#Constant"><tt>Constant</tt></a>s,<a
				1366	href="#Argument"><tt>Argument</tt></a>s. Even <a
				1367	href="#Instruction"><tt>Instruction</tt></a>s and <a
				1368	href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p>
				1369
				1370	<p>A particular <tt>Value</tt> may be used many times in the LLVM representation
				1371	for a program. For example, an incoming argument to a function (represented
				1372	with an instance of the <a href="#Argument">Argument</a> class) is "used" by
				1373	every instruction in the function that references the argument. To keep track
				1374	of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
				1375	href="#User"><tt>User</tt></a>s that is using it (the <a
				1376	href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
				1377	graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
				1378	def-use information in the program, and is accessible through the <tt>use_</tt>*
				1379	methods, shown below.</p>
				1380
				1381	<p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed,
				1382	and this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
				1383	method. In addition, all LLVM values can be named. The "name" of the
				1384	<tt>Value</tt> is a symbolic string printed in the LLVM code:</p>
				1385
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1386	<pre> %<b>foo</b> = add int 1, 2<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1387
				1388	<p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>
				1389	that the name of any value may be missing (an empty string), so names should
				1390	<b>ONLY</b> be used for debugging (making the source code easier to read,
				1391	debugging printouts), they should not be used to keep track of values or map
				1392	between them. For this purpose, use a <tt>std::map</tt> of pointers to the
				1393	<tt>Value</tt> itself instead.</p>
				1394
				1395	<p>One important aspect of LLVM is that there is no distinction between an SSA
				1396	variable and the operation that produces it. Because of this, any reference to
				1397	the value produced by an instruction (or the value available as an incoming
Chris Lattner	d5fc4fc	2004-03-18 14:58:55 +0000	[diff] [blame]	1398	argument, for example) is represented as a direct pointer to the instance of
				1399	the class that
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1400	represents this value. Although this may take some getting used to, it
				1401	simplifies the representation and makes it easier to manipulate.</p>
				1402
				1403	</div>
				1404
				1405	<!-- _______________________________________________________________________ -->
				1406	<div class="doc_subsubsection">
				1407	<a name="m_Value">Important Public Members of the <tt>Value</tt> class</a>
				1408	</div>
				1409
				1410	<div class="doc_text">
				1411
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1412	<ul>
				1413	<li><tt>Value::use_iterator</tt> - Typedef for iterator over the
				1414	use-list<br>
				1415	<tt>Value::use_const_iterator</tt> - Typedef for const_iterator over
				1416	the use-list<br>
				1417	<tt>unsigned use_size()</tt> - Returns the number of users of the
				1418	value.<br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1419	<tt>bool use_empty()</tt> - Returns true if there are no users.<br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1420	<tt>use_iterator use_begin()</tt> - Get an iterator to the start of
				1421	the use-list.<br>
				1422	<tt>use_iterator use_end()</tt> - Get an iterator to the end of the
				1423	use-list.<br>
				1424	<tt><a href="#User">User</a> *use_back()</tt> - Returns the last
				1425	element in the list.
				1426	<p> These methods are the interface to access the def-use
				1427	information in LLVM. As with all other iterators in LLVM, the naming
				1428	conventions follow the conventions defined by the <a href="#stl">STL</a>.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1429	</li>
				1430	<li><tt><a href="#Type">Type</a> *getType() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1431	<p>This method returns the Type of the Value.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1432	</li>
				1433	<li><tt>bool hasName() const</tt><br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1434	<tt>std::string getName() const</tt><br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1435	<tt>void setName(const std::string &Name)</tt>
				1436	<p> This family of methods is used to access and assign a name to a <tt>Value</tt>,
				1437	be aware of the <a href="#nameWarning">precaution above</a>.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1438	</li>
				1439	<li><tt>void replaceAllUsesWith(Value *V)</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1440
				1441	<p>This method traverses the use list of a <tt>Value</tt> changing all <a
				1442	href="#User"><tt>User</tt>s</a> of the current value to refer to
				1443	"<tt>V</tt>" instead. For example, if you detect that an instruction always
				1444	produces a constant value (for example through constant folding), you can
				1445	replace all uses of the instruction with the constant like this:</p>
				1446
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1447	<pre> Inst->replaceAllUsesWith(ConstVal);<br></pre>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1448	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1449
				1450	</div>
				1451
				1452	<!-- ======================================================================= -->
				1453	<div class="doc_subsection">
				1454	<a name="User">The <tt>User</tt> class</a>
				1455	</div>
				1456
				1457	<div class="doc_text">
				1458
				1459	<p>
				1460	<tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt><br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1461	doxygen info: <a href="/doxygen/classllvm_1_1User.html">User Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1462	Superclass: <a href="#Value"><tt>Value</tt></a></p>
				1463
				1464	<p>The <tt>User</tt> class is the common base class of all LLVM nodes that may
				1465	refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
				1466	that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
				1467	referring to. The <tt>User</tt> class itself is a subclass of
				1468	<tt>Value</tt>.</p>
				1469
				1470	<p>The operands of a <tt>User</tt> point directly to the LLVM <a
				1471	href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
				1472	Single Assignment (SSA) form, there can only be one definition referred to,
				1473	allowing this direct connection. This connection provides the use-def
				1474	information in LLVM.</p>
				1475
				1476	</div>
				1477
				1478	<!-- _______________________________________________________________________ -->
				1479	<div class="doc_subsubsection">
				1480	<a name="m_User">Important Public Members of the <tt>User</tt> class</a>
				1481	</div>
				1482
				1483	<div class="doc_text">
				1484
				1485	<p>The <tt>User</tt> class exposes the operand list in two ways: through
				1486	an index access interface and through an iterator based interface.</p>
				1487
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1488	<ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1489	<li><tt>Value *getOperand(unsigned i)</tt><br>
				1490	<tt>unsigned getNumOperands()</tt>
				1491	<p> These two methods expose the operands of the <tt>User</tt> in a
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1492	convenient form for direct access.</p></li>
				1493
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1494	<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand
				1495	list<br>
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	1496	<tt>op_iterator op_begin()</tt> - Get an iterator to the start of
				1497	the operand list.<br>
				1498	<tt>op_iterator op_end()</tt> - Get an iterator to the end of the
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1499	operand list.
				1500	<p> Together, these methods make up the iterator based interface to
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1501	the operands of a <tt>User</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1502	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1503
				1504	</div>
				1505
				1506	<!-- ======================================================================= -->
				1507	<div class="doc_subsection">
				1508	<a name="Instruction">The <tt>Instruction</tt> class</a>
				1509	</div>
				1510
				1511	<div class="doc_text">
				1512
				1513	<p><tt>#include "</tt><tt><a
				1514	href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt><br>
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	1515	doxygen info: <a href="/doxygen/classllvm_1_1Instruction.html">Instruction Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1516	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				1517	href="#Value"><tt>Value</tt></a></p>
				1518
				1519	<p>The <tt>Instruction</tt> class is the common base class for all LLVM
				1520	instructions. It provides only a few methods, but is a very commonly used
				1521	class. The primary data tracked by the <tt>Instruction</tt> class itself is the
				1522	opcode (instruction type) and the parent <a
				1523	href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
				1524	into. To represent a specific type of instruction, one of many subclasses of
				1525	<tt>Instruction</tt> are used.</p>
				1526
				1527	<p> Because the <tt>Instruction</tt> class subclasses the <a
				1528	href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
				1529	way as for other <a href="#User"><tt>User</tt></a>s (with the
				1530	<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
				1531	<tt>op_begin()</tt>/<tt>op_end()</tt> methods).</p> <p> An important file for
				1532	the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> file. This
				1533	file contains some meta-data about the various different types of instructions
				1534	in LLVM. It describes the enum values that are used as opcodes (for example
				1535	<tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), as well as the
				1536	concrete sub-classes of <tt>Instruction</tt> that implement the instruction (for
				1537	example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a
				1538	href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, the use of macros in
				1539	this file confuses doxygen, so these enum values don't show up correctly in the
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	1540	<a href="/doxygen/classllvm_1_1Instruction.html">doxygen output</a>.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1541
				1542	</div>
				1543
				1544	<!-- _______________________________________________________________________ -->
				1545	<div class="doc_subsubsection">
				1546	<a name="m_Instruction">Important Public Members of the <tt>Instruction</tt>
				1547	class</a>
				1548	</div>
				1549
				1550	<div class="doc_text">
				1551
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1552	<ul>
				1553	<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1554	<p>Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that
				1555	this <tt>Instruction</tt> is embedded into.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1556	<li><tt>bool mayWriteToMemory()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1557	<p>Returns true if the instruction writes to memory, i.e. it is a
				1558	<tt>call</tt>,<tt>free</tt>,<tt>invoke</tt>, or <tt>store</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1559	<li><tt>unsigned getOpcode()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1560	<p>Returns the opcode for the <tt>Instruction</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1561	<li><tt><a href="#Instruction">Instruction</a> *clone() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1562	<p>Returns another instance of the specified instruction, identical
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1563	in all ways to the original except that the instruction has no parent
				1564	(ie it's not embedded into a <a href="#BasicBlock"><tt>BasicBlock</tt></a>),
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1565	and it has no name</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1566	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1567
				1568	</div>
				1569
				1570	<!-- ======================================================================= -->
				1571	<div class="doc_subsection">
				1572	<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
				1573	</div>
				1574
				1575	<div class="doc_text">
				1576
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1577	<p><tt>#include "<a
				1578	href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br>
				1579	doxygen info: <a href="/doxygen/structllvm_1_1BasicBlock.html">BasicBlock
				1580	Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1581	Superclass: <a href="#Value"><tt>Value</tt></a></p>
				1582
				1583	<p>This class represents a single entry multiple exit section of the code,
				1584	commonly known as a basic block by the compiler community. The
				1585	<tt>BasicBlock</tt> class maintains a list of <a
				1586	href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block.
				1587	Matching the language definition, the last element of this list of instructions
				1588	is always a terminator instruction (a subclass of the <a
				1589	href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p>
				1590
				1591	<p>In addition to tracking the list of instructions that make up the block, the
				1592	<tt>BasicBlock</tt> class also keeps track of the <a
				1593	href="#Function"><tt>Function</tt></a> that it is embedded into.</p>
				1594
				1595	<p>Note that <tt>BasicBlock</tt>s themselves are <a
				1596	href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
				1597	like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
				1598	<tt>label</tt>.</p>
				1599
				1600	</div>
				1601
				1602	<!-- _______________________________________________________________________ -->
				1603	<div class="doc_subsubsection">
				1604	<a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt>
				1605	class</a>
				1606	</div>
				1607
				1608	<div class="doc_text">
				1609
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1610	<ul>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1611
				1612	<li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1613	href="#Function">Function</a> *Parent = 0)</tt>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1614
				1615	<p>The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
				1616	insertion into a function. The constructor optionally takes a name for the new
				1617	block, and a <a href="#Function"><tt>Function</tt></a> to insert it into. If
				1618	the <tt>Parent</tt> parameter is specified, the new <tt>BasicBlock</tt> is
				1619	automatically inserted at the end of the specified <a
				1620	href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
				1621	manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p></li>
				1622
				1623	<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
				1624	<tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
				1625	<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1626	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1627	STL-style functions for accessing the instruction list.
				1628
				1629	<p>These methods and typedefs are forwarding functions that have the same
				1630	semantics as the standard library methods of the same names. These methods
				1631	expose the underlying instruction list of a basic block in a way that is easy to
				1632	manipulate. To get the full complement of container operations (including
				1633	operations to update the list), you must use the <tt>getInstList()</tt>
				1634	method.</p></li>
				1635
				1636	<li><tt>BasicBlock::InstListType &getInstList()</tt>
				1637
				1638	<p>This method is used to get access to the underlying container that actually
				1639	holds the Instructions. This method must be used when there isn't a forwarding
				1640	function in the <tt>BasicBlock</tt> class for the operation that you would like
				1641	to perform. Because there are no forwarding functions for "updating"
				1642	operations, you need to use this if you want to update the contents of a
				1643	<tt>BasicBlock</tt>.</p></li>
				1644
				1645	<li><tt><a href="#Function">Function</a> *getParent()</tt>
				1646
				1647	<p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
				1648	embedded into, or a null pointer if it is homeless.</p></li>
				1649
				1650	<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt>
				1651
				1652	<p> Returns a pointer to the terminator instruction that appears at the end of
				1653	the <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
				1654	instruction in the block is not a terminator, then a null pointer is
				1655	returned.</p></li>
				1656
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1657	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1658
				1659	</div>
				1660
				1661	<!-- ======================================================================= -->
				1662	<div class="doc_subsection">
				1663	<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
				1664	</div>
				1665
				1666	<div class="doc_text">
				1667
				1668	<p><tt>#include "<a
				1669	href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1670	doxygen info: <a href="/doxygen/classllvm_1_1GlobalValue.html">GlobalValue
				1671	Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1672	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				1673	href="#Value"><tt>Value</tt></a></p>
				1674
				1675	<p>Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
				1676	href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
				1677	visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
				1678	Because they are visible at global scope, they are also subject to linking with
				1679	other globals defined in different translation units. To control the linking
				1680	process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
				1681	<tt>GlobalValue</tt>s know whether they have internal or external linkage, as
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	1682	defined by the <tt>LinkageTypes</tt> enumeration.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1683
				1684	<p>If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
				1685	<tt>static</tt> in C), it is not visible to code outside the current translation
				1686	unit, and does not participate in linking. If it has external linkage, it is
				1687	visible to external code, and does participate in linking. In addition to
				1688	linkage information, <tt>GlobalValue</tt>s keep track of which <a
				1689	href="#Module"><tt>Module</tt></a> they are currently part of.</p>
				1690
				1691	<p>Because <tt>GlobalValue</tt>s are memory objects, they are always referred to
				1692	by their <b>address</b>. As such, the <a href="#Type"><tt>Type</tt></a> of a
				1693	global is always a pointer to its contents. It is important to remember this
				1694	when using the <tt>GetElementPtrInst</tt> instruction because this pointer must
				1695	be dereferenced first. For example, if you have a <tt>GlobalVariable</tt> (a
				1696	subclass of <tt>GlobalValue)</tt> that is an array of 24 ints, type <tt>[24 x
				1697	int]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although
				1698	the address of the first element of this array and the value of the
				1699	<tt>GlobalVariable</tt> are the same, they have different types. The
				1700	<tt>GlobalVariable</tt>'s type is <tt>[24 x int]</tt>. The first element's type
				1701	is <tt>int.</tt> Because of this, accessing a global value requires you to
				1702	dereference the pointer with <tt>GetElementPtrInst</tt> first, then its elements
				1703	can be accessed. This is explained in the <a href="LangRef.html#globalvars">LLVM
				1704	Language Reference Manual</a>.</p>
				1705
				1706	</div>
				1707
				1708	<!-- _______________________________________________________________________ -->
				1709	<div class="doc_subsubsection">
				1710	<a name="m_GlobalValue">Important Public Members of the <tt>GlobalValue</tt>
				1711	class</a>
				1712	</div>
				1713
				1714	<div class="doc_text">
				1715
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1716	<ul>
				1717	<li><tt>bool hasInternalLinkage() const</tt><br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1718	<tt>bool hasExternalLinkage() const</tt><br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1719	<tt>void setInternalLinkage(bool HasInternalLinkage)</tt>
				1720	<p> These methods manipulate the linkage characteristics of the <tt>GlobalValue</tt>.</p>
				1721	<p> </p>
				1722	</li>
				1723	<li><tt><a href="#Module">Module</a> *getParent()</tt>
				1724	<p> This returns the <a href="#Module"><tt>Module</tt></a> that the
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1725	GlobalValue is currently embedded into.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1726	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1727
				1728	</div>
				1729
				1730	<!-- ======================================================================= -->
				1731	<div class="doc_subsection">
				1732	<a name="Function">The <tt>Function</tt> class</a>
				1733	</div>
				1734
				1735	<div class="doc_text">
				1736
				1737	<p><tt>#include "<a
				1738	href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt><br> doxygen
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	1739	info: <a href="/doxygen/classllvm_1_1Function.html">Function Class</a><br>
				1740	Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1741	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
				1742
				1743	<p>The <tt>Function</tt> class represents a single procedure in LLVM. It is
				1744	actually one of the more complex classes in the LLVM heirarchy because it must
				1745	keep track of a large amount of data. The <tt>Function</tt> class keeps track
				1746	of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
				1747	href="#Argument"><tt>Argument</tt></a>s, and a <a
				1748	href="#SymbolTable"><tt>SymbolTable</tt></a>.</p>
				1749
				1750	<p>The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most
				1751	commonly used part of <tt>Function</tt> objects. The list imposes an implicit
				1752	ordering of the blocks in the function, which indicate how the code will be
				1753	layed out by the backend. Additionally, the first <a
				1754	href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
				1755	<tt>Function</tt>. It is not legal in LLVM to explicitly branch to this initial
				1756	block. There are no implicit exit nodes, and in fact there may be multiple exit
				1757	nodes from a single <tt>Function</tt>. If the <a
				1758	href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
				1759	the <tt>Function</tt> is actually a function declaration: the actual body of the
				1760	function hasn't been linked in yet.</p>
				1761
				1762	<p>In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
				1763	<tt>Function</tt> class also keeps track of the list of formal <a
				1764	href="#Argument"><tt>Argument</tt></a>s that the function receives. This
				1765	container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
				1766	nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
				1767	the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.</p>
				1768
				1769	<p>The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used
				1770	LLVM feature that is only used when you have to look up a value by name. Aside
				1771	from that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used
				1772	internally to make sure that there are not conflicts between the names of <a
				1773	href="#Instruction"><tt>Instruction</tt></a>s, <a
				1774	href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
				1775	href="#Argument"><tt>Argument</tt></a>s in the function body.</p>
				1776
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	1777	<p>Note that <tt>Function</tt> is a <a href="#GlobalValue">GlobalValue</a>
				1778	and therefore also a <a href="#Constant">Constant</a>. The value of the function
				1779	is its address (after linking) which is guaranteed to be constant.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1780	</div>
				1781
				1782	<!-- _______________________________________________________________________ -->
				1783	<div class="doc_subsubsection">
				1784	<a name="m_Function">Important Public Members of the <tt>Function</tt>
				1785	class</a>
				1786	</div>
				1787
				1788	<div class="doc_text">
				1789
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1790	<ul>
				1791	<li><tt>Function(const </tt><tt><a href="#FunctionType">FunctionType</a>
Chris Lattner	ac479e5	2004-08-04 05:10:48 +0000	[diff] [blame]	1792	Ty, LinkageTypes Linkage, const std::string &N = "", Module Parent = 0)</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1793
				1794	<p>Constructor used when you need to create new <tt>Function</tt>s to add
				1795	the the program. The constructor must specify the type of the function to
Chris Lattner	ac479e5	2004-08-04 05:10:48 +0000	[diff] [blame]	1796	create and what type of linkage the function should have. The <a
				1797	href="#FunctionType"><tt>FunctionType</tt></a> argument
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1798	specifies the formal arguments and return value for the function. The same
				1799	<a href="#FunctionTypel"><tt>FunctionType</tt></a> value can be used to
				1800	create multiple functions. The <tt>Parent</tt> argument specifies the Module
				1801	in which the function is defined. If this argument is provided, the function
				1802	will automatically be inserted into that module's list of
				1803	functions.</p></li>
				1804
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1805	<li><tt>bool isExternal()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1806
				1807	<p>Return whether or not the <tt>Function</tt> has a body defined. If the
				1808	function is "external", it does not have a body, and thus must be resolved
				1809	by linking with a function defined in a different translation unit.</p></li>
				1810
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1811	<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1812	<tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1813
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1814	<tt>begin()</tt>, <tt>end()</tt>
				1815	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1816
				1817	<p>These are forwarding methods that make it easy to access the contents of
				1818	a <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
				1819	list.</p></li>
				1820
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1821	<li><tt>Function::BasicBlockListType &getBasicBlockList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1822
				1823	<p>Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This
				1824	is necessary to use when you need to update the list or perform a complex
				1825	action that doesn't have a forwarding method.</p></li>
				1826
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1827	<li><tt>Function::arg_iterator</tt> - Typedef for the argument list
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1828	iterator<br>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1829	<tt>Function::const_arg_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1830
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1831	<tt>arg_begin()</tt>, <tt>arg_end()</tt>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1832	<tt>arg_size()</tt>, <tt>arg_empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1833
				1834	<p>These are forwarding methods that make it easy to access the contents of
				1835	a <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a>
				1836	list.</p></li>
				1837
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1838	<li><tt>Function::ArgumentListType &getArgumentList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1839
				1840	<p>Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
				1841	necessary to use when you need to update the list or perform a complex
				1842	action that doesn't have a forwarding method.</p></li>
				1843
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1844	<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryBlock()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1845
				1846	<p>Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
				1847	function. Because the entry block for the function is always the first
				1848	block, this returns the first block of the <tt>Function</tt>.</p></li>
				1849
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1850	<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
				1851	<tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1852
				1853	<p>This traverses the <a href="#Type"><tt>Type</tt></a> of the
				1854	<tt>Function</tt> and returns the return type of the function, or the <a
				1855	href="#FunctionType"><tt>FunctionType</tt></a> of the actual
				1856	function.</p></li>
				1857
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1858	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1859
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1860	<p> Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1861	for this <tt>Function</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1862	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1863
				1864	</div>
				1865
				1866	<!-- ======================================================================= -->
				1867	<div class="doc_subsection">
				1868	<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
				1869	</div>
				1870
				1871	<div class="doc_text">
				1872
				1873	<p><tt>#include "<a
				1874	href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt>
				1875	<br>
Tanya Lattner	a3da777	2004-06-22 08:02:25 +0000	[diff] [blame]	1876	doxygen info: <a href="/doxygen/classllvm_1_1GlobalVariable.html">GlobalVariable
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1877	Class</a><br> Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
				1878	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
				1879
				1880	<p>Global variables are represented with the (suprise suprise)
				1881	<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are also
				1882	subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are
				1883	always referenced by their address (global values must live in memory, so their
				1884	"name" refers to their address). See <a
				1885	href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global variables
				1886	may have an initial value (which must be a <a
				1887	href="#Constant"><tt>Constant</tt></a>), and if they have an initializer, they
				1888	may be marked as "constant" themselves (indicating that their contents never
				1889	change at runtime).</p>
				1890
				1891	</div>
				1892
				1893	<!-- _______________________________________________________________________ -->
				1894	<div class="doc_subsubsection">
				1895	<a name="m_GlobalVariable">Important Public Members of the
				1896	<tt>GlobalVariable</tt> class</a>
				1897	</div>
				1898
				1899	<div class="doc_text">
				1900
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1901	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1902	<li><tt>GlobalVariable(const </tt><tt><a href="#Type">Type</a> *Ty, bool
				1903	isConstant, LinkageTypes& Linkage, <a href="#Constant">Constant</a>
				1904	Initializer = 0, const std::string &Name = "", Module Parent = 0)</tt>
				1905
				1906	<p>Create a new global variable of the specified type. If
				1907	<tt>isConstant</tt> is true then the global variable will be marked as
				1908	unchanging for the program. The Linkage parameter specifies the type of
				1909	linkage (internal, external, weak, linkonce, appending) for the variable. If
				1910	the linkage is InternalLinkage, WeakLinkage, or LinkOnceLinkage,  then
				1911	the resultant global variable will have internal linkage. AppendingLinkage
				1912	concatenates together all instances (in different translation units) of the
				1913	variable into a single variable but is only applicable to arrays.  See
				1914	the <a href="LangRef.html#modulestructure">LLVM Language Reference</a> for
				1915	further details on linkage types. Optionally an initializer, a name, and the
				1916	module to put the variable into may be specified for the global variable as
				1917	well.</p></li>
				1918
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1919	<li><tt>bool isConstant() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1920
				1921	<p>Returns true if this is a global variable that is known not to
				1922	be modified at runtime.</p></li>
				1923
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1924	<li><tt>bool hasInitializer()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1925
				1926	<p>Returns true if this <tt>GlobalVariable</tt> has an intializer.</p></li>
				1927
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1928	<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1929
				1930	<p>Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal
				1931	to call this method if there is no initializer.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1932	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1933
				1934	</div>
				1935
				1936	<!-- ======================================================================= -->
				1937	<div class="doc_subsection">
				1938	<a name="Module">The <tt>Module</tt> class</a>
				1939	</div>
				1940
				1941	<div class="doc_text">
				1942
				1943	<p><tt>#include "<a
				1944	href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt><br> doxygen info:
Tanya Lattner	a3da777	2004-06-22 08:02:25 +0000	[diff] [blame]	1945	<a href="/doxygen/classllvm_1_1Module.html">Module Class</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1946
				1947	<p>The <tt>Module</tt> class represents the top level structure present in LLVM
				1948	programs. An LLVM module is effectively either a translation unit of the
				1949	original program or a combination of several translation units merged by the
				1950	linker. The <tt>Module</tt> class keeps track of a list of <a
				1951	href="#Function"><tt>Function</tt></a>s, a list of <a
				1952	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
				1953	href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
				1954	helpful member functions that try to make common operations easy.</p>
				1955
				1956	</div>
				1957
				1958	<!-- _______________________________________________________________________ -->
				1959	<div class="doc_subsubsection">
				1960	<a name="m_Module">Important Public Members of the <tt>Module</tt> class</a>
				1961	</div>
				1962
				1963	<div class="doc_text">
				1964
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1965	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1966	<li><tt>Module::Module(std::string name = "")</tt></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1967	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1968
				1969	<p>Constructing a <a href="#Module">Module</a> is easy. You can optionally
				1970	provide a name for it (probably based on the name of the translation unit).</p>
				1971
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1972	<ul>
				1973	<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	1974	<tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1975
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1976	<tt>begin()</tt>, <tt>end()</tt>
				1977	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1978
				1979	<p>These are forwarding methods that make it easy to access the contents of
				1980	a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
				1981	list.</p></li>
				1982
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1983	<li><tt>Module::FunctionListType &getFunctionList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1984
				1985	<p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
				1986	necessary to use when you need to update the list or perform a complex
				1987	action that doesn't have a forwarding method.</p>
				1988
				1989	<p><!-- Global Variable --></p></li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1990	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1991
				1992	<hr>
				1993
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1994	<ul>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1995	<li><tt>Module::global_iterator</tt> - Typedef for global variable list iterator<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1996
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1997	<tt>Module::const_global_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1998
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1999	<tt>global_begin()</tt>, <tt>global_end()</tt>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	2000	<tt>global_size()</tt>, <tt>global_empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2001
				2002	<p> These are forwarding methods that make it easy to access the contents of
				2003	a <tt>Module</tt> object's <a
				2004	href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li>
				2005
				2006	<li><tt>Module::GlobalListType &getGlobalList()</tt>
				2007
				2008	<p>Returns the list of <a
				2009	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. This is necessary to
				2010	use when you need to update the list or perform a complex action that
				2011	doesn't have a forwarding method.</p>
				2012
				2013	<p><!-- Symbol table stuff --> </p></li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2014	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2015
				2016	<hr>
				2017
				2018	<ul>
				2019	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
				2020
				2021	<p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
				2022	for this <tt>Module</tt>.</p>
				2023
				2024	<p><!-- Convenience methods --></p></li>
				2025	</ul>
				2026
				2027	<hr>
				2028
				2029	<ul>
				2030	<li><tt><a href="#Function">Function</a> *getFunction(const std::string
				2031	&Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt>
				2032
				2033	<p>Look up the specified function in the <tt>Module</tt> <a
				2034	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
				2035	<tt>null</tt>.</p></li>
				2036
				2037	<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const
				2038	std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt>
				2039
				2040	<p>Look up the specified function in the <tt>Module</tt> <a
				2041	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
				2042	external declaration for the function and return it.</p></li>
				2043
				2044	<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt>
				2045
				2046	<p>If there is at least one entry in the <a
				2047	href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
				2048	href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
				2049	string.</p></li>
				2050
				2051	<li><tt>bool addTypeName(const std::string &Name, const <a
				2052	href="#Type">Type</a> *Ty)</tt>
				2053
				2054	<p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
				2055	mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this
				2056	name, true is returned and the <a
				2057	href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li>
				2058	</ul>
				2059
				2060	</div>
				2061
				2062	<!-- ======================================================================= -->
				2063	<div class="doc_subsection">
				2064	<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
				2065	</div>
				2066
				2067	<div class="doc_text">
				2068
				2069	<p>Constant represents a base class for different types of constants. It
				2070	is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
				2071	ConstantArray etc for representing the various types of Constants.</p>
				2072
				2073	</div>
				2074
				2075	<!-- _______________________________________________________________________ -->
				2076	<div class="doc_subsubsection">
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2077	<a name="m_Constant">Important Public Methods</a>
				2078	</div>
				2079	<div class="doc_text">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2080	</div>
				2081
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2082	<!-- _______________________________________________________________________ -->
				2083	<div class="doc_subsubsection">Important Subclasses of Constant </div>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2084	<div class="doc_text">
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2085	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2086	<li>ConstantSInt : This subclass of Constant represents a signed integer
				2087	constant.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2088	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2089	<li><tt>int64_t getValue() const</tt>: Returns the underlying value of
				2090	this constant. </li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2091	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2092	</li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2093	<li>ConstantUInt : This class represents an unsigned integer.
				2094	<ul>
				2095	<li><tt>uint64_t getValue() const</tt>: Returns the underlying value of
				2096	this constant. </li>
				2097	</ul>
				2098	</li>
				2099	<li>ConstantFP : This class represents a floating point constant.
				2100	<ul>
				2101	<li><tt>double getValue() const</tt>: Returns the underlying value of
				2102	this constant. </li>
				2103	</ul>
				2104	</li>
				2105	<li>ConstantBool : This represents a boolean constant.
				2106	<ul>
				2107	<li><tt>bool getValue() const</tt>: Returns the underlying value of this
				2108	constant. </li>
				2109	</ul>
				2110	</li>
				2111	<li>ConstantArray : This represents a constant array.
				2112	<ul>
				2113	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	2114	a vector of component constants that makeup this array. </li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2115	</ul>
				2116	</li>
				2117	<li>ConstantStruct : This represents a constant struct.
				2118	<ul>
				2119	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	2120	a vector of component constants that makeup this array. </li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2121	</ul>
				2122	</li>
				2123	<li>GlobalValue : This represents either a global variable or a function. In
				2124	either case, the value is a constant fixed address (after linking).
				2125	</li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2126	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2127	</div>
				2128
				2129	<!-- ======================================================================= -->
				2130	<div class="doc_subsection">
				2131	<a name="Type">The <tt>Type</tt> class and Derived Types</a>
				2132	</div>
				2133
				2134	<div class="doc_text">
				2135
				2136	<p>Type as noted earlier is also a subclass of a Value class. Any primitive
				2137	type (like int, short etc) in LLVM is an instance of Type Class. All other
				2138	types are instances of subclasses of type like FunctionType, ArrayType
				2139	etc. DerivedType is the interface for all such dervied types including
				2140	FunctionType, ArrayType, PointerType, StructType. Types can have names. They can
				2141	be recursive (StructType). There exists exactly one instance of any type
				2142	structure at a time. This allows using pointer equality of Type *s for comparing
				2143	types.</p>
				2144
				2145	</div>
				2146
				2147	<!-- _______________________________________________________________________ -->
				2148	<div class="doc_subsubsection">
				2149	<a name="m_Value">Important Public Methods</a>
				2150	</div>
				2151
				2152	<div class="doc_text">
				2153
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2154	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2155
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2156	<li><tt>bool isSigned() const</tt>: Returns whether an integral numeric type
				2157	is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is
				2158	not true for Float and Double. </li>
				2159
				2160	<li><tt>bool isUnsigned() const</tt>: Returns whether a numeric type is
				2161	unsigned. This is not quite the complement of isSigned... nonnumeric types
				2162	return false as they do with isSigned. This returns true for UByteTy,
				2163	UShortTy, UIntTy, and ULongTy. </li>
				2164
Chris Lattner	4573f1b	2004-07-08 17:49:37 +0000	[diff] [blame]	2165	<li><tt>bool isInteger() const</tt>: Equivalent to isSigned() \|\| isUnsigned().</li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2166
				2167	<li><tt>bool isIntegral() const</tt>: Returns true if this is an integral
				2168	type, which is either Bool type or one of the Integer types.</li>
				2169
				2170	<li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two
				2171	floating point types.</li>
				2172
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2173	<li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if
				2174	this type can be converted to 'Ty' without any reinterpretation of bits. For
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	2175	example, uint to int or one pointer type to another.</li>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	2176	</ul>
				2177	</div>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2178
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	2179	<!-- _______________________________________________________________________ -->
				2180	<div class="doc_subsubsection">
				2181	<a name="m_Value">Important Derived Types</a>
				2182	</div>
				2183	<div class="doc_text">
				2184	<ul>
				2185	<li>SequentialType : This is subclassed by ArrayType and PointerType
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2186	<ul>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	2187	<li><tt>const Type * getElementType() const</tt>: Returns the type of each
				2188	of the elements in the sequential type. </li>
				2189	</ul>
				2190	</li>
				2191	<li>ArrayType : This is a subclass of SequentialType and defines interface for
				2192	array types.
				2193	<ul>
				2194	<li><tt>unsigned getNumElements() const</tt>: Returns the number of
				2195	elements in the array. </li>
				2196	</ul>
				2197	</li>
				2198	<li>PointerType : Subclass of SequentialType for pointer types. </li>
				2199	<li>StructType : subclass of DerivedTypes for struct types </li>
				2200	<li>FunctionType : subclass of DerivedTypes for function types.
				2201	<ul>
				2202	<li><tt>bool isVarArg() const</tt>: Returns true if its a vararg
				2203	function</li>
				2204	<li><tt> const Type * getReturnType() const</tt>: Returns the
				2205	return type of the function.</li>
				2206	<li><tt>const Type * getParamType (unsigned i)</tt>: Returns
				2207	the type of the ith parameter.</li>
				2208	<li><tt> const unsigned getNumParams() const</tt>: Returns the
				2209	number of formal parameters.</li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2210	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2211	</li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2212	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2213	</div>
				2214
				2215	<!-- ======================================================================= -->
				2216	<div class="doc_subsection">
				2217	<a name="Argument">The <tt>Argument</tt> class</a>
				2218	</div>
				2219
				2220	<div class="doc_text">
				2221
				2222	<p>This subclass of Value defines the interface for incoming formal
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	2223	arguments to a function. A Function maintains a list of its formal
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2224	arguments. An argument has a pointer to the parent Function.</p>
				2225
				2226	</div>
				2227
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	2228	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2229	<hr>
				2230	<address>
				2231	<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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				2234	src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
				2235
				2236	<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
				2237	<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
				2238	<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
				2239	Last modified: $Date$
				2240	</address>
				2241
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2242	</body>
				2243	</html>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	2244	<!-- vim: sw=2 noai
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