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Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	3	<html>
				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">
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	7	</head>
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	f623a08	2005-10-17 01:36:23 +0000	[diff] [blame^]	44	<li><a href="#ViewGraph">Viewing graphs while debugging code</a></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	45	</ul>
				46	</li>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	47	<li><a href="#common">Helpful Hints for Common Operations</a>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	48	<ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	49	<li><a href="#inspection">Basic Inspection and Traversal Routines</a>
				50	<ul>
				51	<li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
				52	in a <tt>Function</tt></a> </li>
				53	<li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
				54	in a <tt>BasicBlock</tt></a> </li>
				55	<li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
				56	in a <tt>Function</tt></a> </li>
				57	<li><a href="#iterate_convert">Turning an iterator into a
				58	class pointer</a> </li>
				59	<li><a href="#iterate_complex">Finding call sites: a more
				60	complex example</a> </li>
				61	<li><a href="#calls_and_invokes">Treating calls and invokes
				62	the same way</a> </li>
				63	<li><a href="#iterate_chains">Iterating over def-use &
				64	use-def chains</a> </li>
				65	</ul>
				66	</li>
				67	<li><a href="#simplechanges">Making simple changes</a>
				68	<ul>
				69	<li><a href="#schanges_creating">Creating and inserting new
				70	<tt>Instruction</tt>s</a> </li>
				71	<li><a href="#schanges_deleting">Deleting <tt>Instruction</tt>s</a> </li>
				72	<li><a href="#schanges_replacing">Replacing an <tt>Instruction</tt>
				73	with another <tt>Value</tt></a> </li>
				74	</ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	75	</li>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	76	<!--
				77	<li>Working with the Control Flow Graph
				78	<ul>
				79	<li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
				80	<li>
				81	<li>
				82	</ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	83	-->
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	84	</ul>
				85	</li>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	86
				87	<li><a href="#advanced">Advanced Topics</a>
				88	<ul>
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	89	<li><a href="#TypeResolve">LLVM Type Resolution</a>
				90	<ul>
				91	<li><a href="#BuildRecType">Basic Recursive Type Construction</a></li>
				92	<li><a href="#refineAbstractTypeTo">The <tt>refineAbstractTypeTo</tt> method</a></li>
				93	<li><a href="#PATypeHolder">The PATypeHolder Class</a></li>
				94	<li><a href="#AbstractTypeUser">The AbstractTypeUser Class</a></li>
				95	</ul></li>
				96
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	97	<li><a href="#SymbolTable">The <tt>SymbolTable</tt> class </a></li>
				98	</ul></li>
				99
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	100	<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	101	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	102	<li><a href="#Value">The <tt>Value</tt> class</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	103	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	104	<li><a href="#User">The <tt>User</tt> class</a>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	105	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	106	<li><a href="#Instruction">The <tt>Instruction</tt> class</a>
				107	<ul>
				108	<li><a href="#GetElementPtrInst">The <tt>GetElementPtrInst</tt> class</a></li>
				109	</ul>
				110	</li>
				111	<li><a href="#Module">The <tt>Module</tt> class</a></li>
				112	<li><a href="#Constant">The <tt>Constant</tt> class</a>
				113	<ul>
				114	<li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
				115	<ul>
				116	<li><a href="#BasicBlock">The <tt>BasicBlock</tt>class</a></li>
				117	<li><a href="#Function">The <tt>Function</tt> class</a></li>
				118	<li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a></li>
				119	</ul>
				120	</li>
				121	</ul>
				122	</li>
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	123	</ul>
				124	</li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	125	<li><a href="#Type">The <tt>Type</tt> class</a> </li>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	126	<li><a href="#Argument">The <tt>Argument</tt> class</a></li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	127	</ul>
				128	</li>
				129	</ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	130	</li>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	131	</ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	132
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	133	<div class="doc_author">
				134	<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
Chris Lattner	94c4359	2004-05-26 16:52:55 +0000	[diff] [blame]	135	<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>,
				136	<a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a>, and
				137	<a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	138	</div>
				139
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	140	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	141	<div class="doc_section">
				142	<a name="introduction">Introduction </a>
				143	</div>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	144	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	145
				146	<div class="doc_text">
				147
				148	<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]	149	interfaces available in the LLVM source-base. This manual is not
				150	intended to explain what LLVM is, how it works, and what LLVM code looks
				151	like. It assumes that you know the basics of LLVM and are interested
				152	in writing transformations or otherwise analyzing or manipulating the
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	153	code.</p>
				154
				155	<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]	156	way in the continuously growing source code that makes up the LLVM
				157	infrastructure. Note that this manual is not intended to serve as a
				158	replacement for reading the source code, so if you think there should be
				159	a method in one of these classes to do something, but it's not listed,
				160	check the source. Links to the <a href="/doxygen/">doxygen</a> sources
				161	are provided to make this as easy as possible.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	162
				163	<p>The first section of this document describes general information that is
				164	useful to know when working in the LLVM infrastructure, and the second describes
				165	the Core LLVM classes. In the future this manual will be extended with
				166	information describing how to use extension libraries, such as dominator
				167	information, CFG traversal routines, and useful utilities like the <tt><a
				168	href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.</p>
				169
				170	</div>
				171
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	172	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	173	<div class="doc_section">
				174	<a name="general">General Information</a>
				175	</div>
				176	<!-- *********************************************************************** -->
				177
				178	<div class="doc_text">
				179
				180	<p>This section contains general information that is useful if you are working
				181	in the LLVM source-base, but that isn't specific to any particular API.</p>
				182
				183	</div>
				184
				185	<!-- ======================================================================= -->
				186	<div class="doc_subsection">
				187	<a name="stl">The C++ Standard Template Library</a>
				188	</div>
				189
				190	<div class="doc_text">
				191
				192	<p>LLVM makes heavy use of the C++ Standard Template Library (STL),
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	193	perhaps much more than you are used to, or have seen before. Because of
				194	this, you might want to do a little background reading in the
				195	techniques used and capabilities of the library. There are many good
				196	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]	197	can get, so it will not be discussed in this document.</p>
				198
				199	<p>Here are some useful links:</p>
				200
				201	<ol>
				202
				203	<li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++ Library
				204	reference</a> - an excellent reference for the STL and other parts of the
				205	standard C++ library.</li>
				206
				207	<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]	208	O'Reilly book in the making. It has a decent
				209	Standard Library
				210	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]	211	published.</li>
				212
				213	<li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
				214	Questions</a></li>
				215
				216	<li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
				217	Contains a useful <a
				218	href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
				219	STL</a>.</li>
				220
				221	<li><a href="http://www.research.att.com/%7Ebs/C++.html">Bjarne Stroustrup's C++
				222	Page</a></li>
				223
Tanya Lattner	79445ba	2004-12-08 18:34:56 +0000	[diff] [blame]	224	<li><a href="http://64.78.49.204/">
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	225	Bruce Eckel's Thinking in C++, 2nd ed. Volume 2 Revision 4.0 (even better, get
				226	the book).</a></li>
				227
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	228	</ol>
				229
				230	<p>You are also encouraged to take a look at the <a
				231	href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
				232	to write maintainable code more than where to put your curly braces.</p>
				233
				234	</div>
				235
				236	<!-- ======================================================================= -->
				237	<div class="doc_subsection">
				238	<a name="stl">Other useful references</a>
				239	</div>
				240
				241	<div class="doc_text">
				242
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	243	<ol>
				244	<li><a href="http://www.psc.edu/%7Esemke/cvs_branches.html">CVS
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	245	Branch and Tag Primer</a></li>
Misha Brukman	a0f71e4	2004-06-18 18:39:00 +0000	[diff] [blame]	246	<li><a href="http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html">Using
				247	static and shared libraries across platforms</a></li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	248	</ol>
				249
				250	</div>
				251
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	252	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	253	<div class="doc_section">
				254	<a name="apis">Important and useful LLVM APIs</a>
				255	</div>
				256	<!-- *********************************************************************** -->
				257
				258	<div class="doc_text">
				259
				260	<p>Here we highlight some LLVM APIs that are generally useful and good to
				261	know about when writing transformations.</p>
				262
				263	</div>
				264
				265	<!-- ======================================================================= -->
				266	<div class="doc_subsection">
				267	<a name="isa">The isa<>, cast<> and dyn_cast<> templates</a>
				268	</div>
				269
				270	<div class="doc_text">
				271
				272	<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]	273	These templates have many similarities to the C++ <tt>dynamic_cast<></tt>
				274	operator, but they don't have some drawbacks (primarily stemming from
				275	the fact that <tt>dynamic_cast<></tt> only works on classes that
				276	have a v-table). Because they are used so often, you must know what they
				277	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]	278	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]	279	file (note that you very rarely have to include this file directly).</p>
				280
				281	<dl>
				282	<dt><tt>isa<></tt>: </dt>
				283
				284	<dd>The <tt>isa<></tt> operator works exactly like the Java
				285	"<tt>instanceof</tt>" operator. It returns true or false depending on whether
				286	a reference or pointer points to an instance of the specified class. This can
				287	be very useful for constraint checking of various sorts (example below).</dd>
				288
				289	<dt><tt>cast<></tt>: </dt>
				290
				291	<dd>The <tt>cast<></tt> operator is a "checked cast" operation. It
				292	converts a pointer or reference from a base class to a derived cast, causing
				293	an assertion failure if it is not really an instance of the right type. This
				294	should be used in cases where you have some information that makes you believe
				295	that something is of the right type. An example of the <tt>isa<></tt>
				296	and <tt>cast<></tt> template is:
				297
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	298	<pre>
				299	static bool isLoopInvariant(const <a href="#Value">Value</a> V, const Loop L) {
				300	if (isa<<a href="#Constant">Constant</a>>(V) \|\| isa<<a href="#Argument">Argument</a>>(V) \|\| isa<<a href="#GlobalValue">GlobalValue</a>>(V))
				301	return true;
				302
Chris Lattner	53f72b3	2005-04-22 04:49:59 +0000	[diff] [blame]	303	<i>// Otherwise, it must be an instruction...</i>
				304	return !L->contains(cast<<a href="#Instruction">Instruction</a>>(V)->getParent());
				305	}
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	306	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	307
				308	<p>Note that you should <b>not</b> use an <tt>isa<></tt> test followed
				309	by a <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt>
				310	operator.</p>
				311
				312	</dd>
				313
				314	<dt><tt>dyn_cast<></tt>:</dt>
				315
				316	<dd>The <tt>dyn_cast<></tt> operator is a "checking cast" operation. It
				317	checks to see if the operand is of the specified type, and if so, returns a
				318	pointer to it (this operator does not work with references). If the operand is
				319	not of the correct type, a null pointer is returned. Thus, this works very
				320	much like the <tt>dynamic_cast</tt> operator in C++, and should be used in the
				321	same circumstances. Typically, the <tt>dyn_cast<></tt> operator is used
				322	in an <tt>if</tt> statement or some other flow control statement like this:
				323
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	324	<pre>
				325	if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a href="#AllocationInst">AllocationInst</a>>(Val)) {
				326	...
				327	}
				328	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	329
				330	<p> This form of the <tt>if</tt> statement effectively combines together a
				331	call to <tt>isa<></tt> and a call to <tt>cast<></tt> into one
				332	statement, which is very convenient.</p>
				333
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	334	<p>Note that the <tt>dyn_cast<></tt> operator, like C++'s
				335	<tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused.
				336	In particular you should not use big chained <tt>if/then/else</tt> blocks to
				337	check for lots of different variants of classes. If you find yourself
				338	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]	339	<tt>InstVisitor</tt> class to dispatch over the instruction type directly.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	340
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	341	</dd>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	342
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	343	<dt><tt>cast_or_null<></tt>: </dt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	344
				345	<dd>The <tt>cast_or_null<></tt> operator works just like the
				346	<tt>cast<></tt> operator, except that it allows for a null pointer as
				347	an argument (which it then propagates). This can sometimes be useful,
				348	allowing you to combine several null checks into one.</dd>
				349
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	350	<dt><tt>dyn_cast_or_null<></tt>: </dt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	351
				352	<dd>The <tt>dyn_cast_or_null<></tt> operator works just like the
				353	<tt>dyn_cast<></tt> operator, except that it allows for a null pointer
				354	as an argument (which it then propagates). This can sometimes be useful,
				355	allowing you to combine several null checks into one.</dd>
				356
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	357	</dl>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	358
				359	<p>These five templates can be used with any classes, whether they have a
				360	v-table or not. To add support for these templates, you simply need to add
				361	<tt>classof</tt> static methods to the class you are interested casting
				362	to. Describing this is currently outside the scope of this document, but there
				363	are lots of examples in the LLVM source base.</p>
				364
				365	</div>
				366
				367	<!-- ======================================================================= -->
				368	<div class="doc_subsection">
				369	<a name="DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> option</a>
				370	</div>
				371
				372	<div class="doc_text">
				373
				374	<p>Often when working on your pass you will put a bunch of debugging printouts
				375	and other code into your pass. After you get it working, you want to remove
				376	it... but you may need it again in the future (to work out new bugs that you run
				377	across).</p>
				378
				379	<p> Naturally, because of this, you don't want to delete the debug printouts,
				380	but you don't want them to always be noisy. A standard compromise is to comment
				381	them out, allowing you to enable them if you need them in the future.</p>
				382
Chris Lattner	695b78b	2005-04-26 22:56:16 +0000	[diff] [blame]	383	<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]	384	file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to
				385	this problem. Basically, you can put arbitrary code into the argument of the
				386	<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other
				387	tool) is run with the '<tt>-debug</tt>' command line argument:</p>
				388
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	389	<pre> ... <br> DEBUG(std::cerr << "I am here!\n");<br> ...<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	390
				391	<p>Then you can run your pass like this:</p>
				392
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	393	<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]	394
				395	<p>Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you
				396	to not have to create "yet another" command line option for the debug output for
				397	your pass. Note that <tt>DEBUG()</tt> macros are disabled for optimized builds,
				398	so they do not cause a performance impact at all (for the same reason, they
				399	should also not contain side-effects!).</p>
				400
				401	<p>One additional nice thing about the <tt>DEBUG()</tt> macro is that you can
				402	enable or disable it directly in gdb. Just use "<tt>set DebugFlag=0</tt>" or
				403	"<tt>set DebugFlag=1</tt>" from the gdb if the program is running. If the
				404	program hasn't been started yet, you can always just run it with
				405	<tt>-debug</tt>.</p>
				406
				407	</div>
				408
				409	<!-- _______________________________________________________________________ -->
				410	<div class="doc_subsubsection">
Chris Lattner	c915108	2005-04-26 22:57:07 +0000	[diff] [blame]	411	<a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt> and
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	412	the <tt>-debug-only</tt> option</a>
				413	</div>
				414
				415	<div class="doc_text">
				416
				417	<p>Sometimes you may find yourself in a situation where enabling <tt>-debug</tt>
				418	just turns on <b>too much</b> information (such as when working on the code
				419	generator). If you want to enable debug information with more fine-grained
				420	control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only
				421	option as follows:</p>
				422
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	423	<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]	424
				425	<p>Then you can run your pass like this:</p>
				426
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	427	<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]	428
				429	<p>Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of
				430	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]	431	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]	432	<tt>#undef</tt>'s). Also, you should use names more meaningful than "foo" and
				433	"bar", because there is no system in place to ensure that names do not
				434	conflict. If two different modules use the same string, they will all be turned
				435	on when the name is specified. This allows, for example, all debug information
				436	for instruction scheduling to be enabled with <tt>-debug-type=InstrSched</tt>,
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	437	even if the source lives in multiple files.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	438
				439	</div>
				440
				441	<!-- ======================================================================= -->
				442	<div class="doc_subsection">
				443	<a name="Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt>
				444	option</a>
				445	</div>
				446
				447	<div class="doc_text">
				448
				449	<p>The "<tt><a
Chris Lattner	695b78b	2005-04-26 22:56:16 +0000	[diff] [blame]	450	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]	451	provides a template named <tt>Statistic</tt> that is used as a unified way to
				452	keep track of what the LLVM compiler is doing and how effective various
				453	optimizations are. It is useful to see what optimizations are contributing to
				454	making a particular program run faster.</p>
				455
				456	<p>Often you may run your pass on some big program, and you're interested to see
				457	how many times it makes a certain transformation. Although you can do this with
				458	hand inspection, or some ad-hoc method, this is a real pain and not very useful
				459	for big programs. Using the <tt>Statistic</tt> template makes it very easy to
				460	keep track of this information, and the calculated information is presented in a
				461	uniform manner with the rest of the passes being executed.</p>
				462
				463	<p>There are many examples of <tt>Statistic</tt> uses, but the basics of using
				464	it are as follows:</p>
				465
				466	<ol>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	467	<li>Define your statistic like this:
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	468	<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]	469
				470	<p>The <tt>Statistic</tt> template can emulate just about any data-type,
				471	but if you do not specify a template argument, it defaults to acting like
				472	an unsigned int counter (this is usually what you want).</p></li>
				473
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	474	<li>Whenever you make a transformation, bump the counter:
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	475	<pre> ++NumXForms; // I did stuff<br></pre>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	476	</li>
				477	</ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	478
				479	<p>That's all you have to do. To get '<tt>opt</tt>' to print out the
				480	statistics gathered, use the '<tt>-stats</tt>' option:</p>
				481
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	482	<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]	483
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	484	<p> When running <tt>gccas</tt> on a C file from the SPEC benchmark
				485	suite, it gives a report that looks like this:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	486
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	487	<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]	488
				489	<p>Obviously, with so many optimizations, having a unified framework for this
				490	stuff is very nice. Making your pass fit well into the framework makes it more
				491	maintainable and useful.</p>
				492
				493	</div>
				494
Chris Lattner	f623a08	2005-10-17 01:36:23 +0000	[diff] [blame^]	495	<!-- ======================================================================= -->
				496	<div class="doc_subsection">
				497	<a name="ViewGraph">Viewing graphs while debugging code</a>
				498	</div>
				499
				500	<div class="doc_text">
				501
				502	<p>Several of the important data structures in LLVM are graphs: for example
				503	CFGs made out of LLVM <a href="#BasicBlock">BasicBlock</a>s, CFGs made out of
				504	LLVM <a href="CodeGenerator.html#machinebasicblock">MachineBasicBlock</a>s, and
				505	<a href="CodeGenerator.html#selectiondag_intro">Instruction Selection
				506	DAGs</a>. In many cases, while debugging various parts of the compiler, it is
				507	nice to instantly visualize these graphs.</p>
				508
				509	<p>LLVM provides several callbacks that are available in a debug build to do
				510	exactly that. If you call the <tt>Function::viewCFG()</tt> method, for example,
				511	the current LLVM tool will pop up a window containing the CFG for the function
				512	where each basic block is a node in the graph, and each node contains the
				513	instructions in the block. Similarly, there also exists
				514	<tt>Function::viewCFGOnly()</tt> (does not include the instructions), the
				515	<tt>MachineFunction::viewCFG()</tt> and <tt>MachineFunction::viewCFGOnly()</tt>,
				516	and the <tt>SelectionDAG::viewGraph()</tt> methods. Within GDB, for example,
				517	you can usually use something like "<tt>call DAG.viewGraph()</tt>" to pop
				518	up a window. Alternatively, you can sprinkle calls to these functions in your
				519	code in places you want to debug.</p>
				520
				521	<p>Getting this to work requires a small amount of configuration. On Unix
				522	systems with X11, install the <a href="http://www.graphviz.org">graphviz</a>
				523	toolkit, and make sure 'dot' and 'gv' are in your path. If you are running on
				524	Mac OS/X, download and install the Mac OS/X <a
				525	href="http://www.pixelglow.com/graphviz/">Graphviz program</a>, and add
				526	<tt>/Applications/Graphviz.app/Contents/MacOS/</tt> (or whereever you install
				527	it) to your path. Once in your system and path are set up, rerun the LLVM
				528	configure script and rebuild LLVM to enable this functionality.</p>
				529
				530	</div>
				531
				532
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	533	<!-- *********************************************************************** -->
				534	<div class="doc_section">
				535	<a name="common">Helpful Hints for Common Operations</a>
				536	</div>
				537	<!-- *********************************************************************** -->
				538
				539	<div class="doc_text">
				540
				541	<p>This section describes how to perform some very simple transformations of
				542	LLVM code. This is meant to give examples of common idioms used, showing the
				543	practical side of LLVM transformations. <p> Because this is a "how-to" section,
				544	you should also read about the main classes that you will be working with. The
				545	<a href="#coreclasses">Core LLVM Class Hierarchy Reference</a> contains details
				546	and descriptions of the main classes that you should know about.</p>
				547
				548	</div>
				549
				550	<!-- NOTE: this section should be heavy on example code -->
				551	<!-- ======================================================================= -->
				552	<div class="doc_subsection">
				553	<a name="inspection">Basic Inspection and Traversal Routines</a>
				554	</div>
				555
				556	<div class="doc_text">
				557
				558	<p>The LLVM compiler infrastructure have many different data structures that may
				559	be traversed. Following the example of the C++ standard template library, the
				560	techniques used to traverse these various data structures are all basically the
				561	same. For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or
				562	method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt>
				563	function returns an iterator pointing to one past the last valid element of the
				564	sequence, and there is some <tt>XXXiterator</tt> data type that is common
				565	between the two operations.</p>
				566
				567	<p>Because the pattern for iteration is common across many different aspects of
				568	the program representation, the standard template library algorithms may be used
				569	on them, and it is easier to remember how to iterate. First we show a few common
				570	examples of the data structures that need to be traversed. Other data
				571	structures are traversed in very similar ways.</p>
				572
				573	</div>
				574
				575	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	576	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	577	<a name="iterate_function">Iterating over the </a><a
				578	href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a
				579	href="#Function"><tt>Function</tt></a>
				580	</div>
				581
				582	<div class="doc_text">
				583
				584	<p>It's quite common to have a <tt>Function</tt> instance that you'd like to
				585	transform in some way; in particular, you'd like to manipulate its
				586	<tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over all of
				587	the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>. The following is
				588	an example that prints the name of a <tt>BasicBlock</tt> and the number of
				589	<tt>Instruction</tt>s it contains:</p>
				590
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	591	<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]	592
				593	<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]	594	invoking member functions of the <tt>Instruction</tt> class. This is
				595	because the indirection operator is overloaded for the iterator
Chris Lattner	7496ec5	2003-08-05 22:54:23 +0000	[diff] [blame]	596	classes. In the above code, the expression <tt>i->size()</tt> is
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	597	exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.</p>
				598
				599	</div>
				600
				601	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	602	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	603	<a name="iterate_basicblock">Iterating over the </a><a
				604	href="#Instruction"><tt>Instruction</tt></a>s in a <a
				605	href="#BasicBlock"><tt>BasicBlock</tt></a>
				606	</div>
				607
				608	<div class="doc_text">
				609
				610	<p>Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, it's
				611	easy to iterate over the individual instructions that make up
				612	<tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in
				613	a <tt>BasicBlock</tt>:</p>
				614
Chris Lattner	55c0461	2005-03-06 06:00:13 +0000	[diff] [blame]	615	<pre>
				616	// blk is a pointer to a BasicBlock instance
				617	for (BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)
				618	// the next statement works since operator<<(ostream&,...)
				619	// is overloaded for Instruction&
				620	std::cerr << *i << "\n";
				621	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	622
				623	<p>However, this isn't really the best way to print out the contents of a
				624	<tt>BasicBlock</tt>! Since the ostream operators are overloaded for virtually
				625	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]	626	basic block itself: <tt>std::cerr << *blk << "\n";</tt>.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	627
				628	</div>
				629
				630	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	631	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	632	<a name="iterate_institer">Iterating over the </a><a
				633	href="#Instruction"><tt>Instruction</tt></a>s in a <a
				634	href="#Function"><tt>Function</tt></a>
				635	</div>
				636
				637	<div class="doc_text">
				638
				639	<p>If you're finding that you commonly iterate over a <tt>Function</tt>'s
				640	<tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s <tt>Instruction</tt>s,
				641	<tt>InstIterator</tt> should be used instead. You'll need to include <a
				642	href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>,
				643	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]	644	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]	645
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	646	<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]	647	Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
				648	worklist with its initial contents. For example, if you wanted to
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	649	initialize a worklist to contain all instructions in a <tt>Function</tt>
				650	F, all you would need to do is something like:
				651	<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]	652
				653	<p>The STL set <tt>worklist</tt> would now contain all instructions in the
				654	<tt>Function</tt> pointed to by F.</p>
				655
				656	</div>
				657
				658	<!-- _______________________________________________________________________ -->
				659	<div class="doc_subsubsection">
				660	<a name="iterate_convert">Turning an iterator into a class pointer (and
				661	vice-versa)</a>
				662	</div>
				663
				664	<div class="doc_text">
				665
				666	<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]	667	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]	668	a reference or a pointer from an iterator is very straight-forward.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	669	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]	670	is a <tt>BasicBlock::const_iterator</tt>:</p>
				671
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	672	<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]	673
				674	<p>However, the iterators you'll be working with in the LLVM framework are
				675	special: they will automatically convert to a ptr-to-instance type whenever they
				676	need to. Instead of dereferencing the iterator and then taking the address of
				677	the result, you can simply assign the iterator to the proper pointer type and
				678	you get the dereference and address-of operation as a result of the assignment
				679	(behind the scenes, this is a result of overloading casting mechanisms). Thus
				680	the last line of the last example,</p>
				681
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	682	<pre>Instruction* pinst = &*i;</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	683
				684	<p>is semantically equivalent to</p>
				685
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	686	<pre>Instruction* pinst = i;</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	687
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	688	<p>It's also possible to turn a class pointer into the corresponding iterator,
				689	and this is a constant time operation (very efficient). The following code
				690	snippet illustrates use of the conversion constructors provided by LLVM
				691	iterators. By using these, you can explicitly grab the iterator of something
				692	without actually obtaining it via iteration over some structure:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	693
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	694	<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]	695
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	696	</div>
				697
				698	<!--_______________________________________________________________________-->
				699	<div class="doc_subsubsection">
				700	<a name="iterate_complex">Finding call sites: a slightly more complex
				701	example</a>
				702	</div>
				703
				704	<div class="doc_text">
				705
				706	<p>Say that you're writing a FunctionPass and would like to count all the
				707	locations in the entire module (that is, across every <tt>Function</tt>) where a
				708	certain function (i.e., some <tt>Function</tt>*) is already in scope. As you'll
				709	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]	710	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]	711	you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this
				712	is what we want to do:</p>
				713
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	714	<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]	715
				716	<p>And the actual code is (remember, since we're writing a
				717	<tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply has to
				718	override the <tt>runOnFunction</tt> method...):</p>
				719
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	720	<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
				721	href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a
				722	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]	723
				724	</div>
				725
Brian Gaeke	f1972c6	2003-11-07 19:25:45 +0000	[diff] [blame]	726	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	727	<div class="doc_subsubsection">
				728	<a name="calls_and_invokes">Treating calls and invokes the same way</a>
				729	</div>
				730
				731	<div class="doc_text">
				732
				733	<p>You may have noticed that the previous example was a bit oversimplified in
				734	that it did not deal with call sites generated by 'invoke' instructions. In
				735	this, and in other situations, you may find that you want to treat
				736	<tt>CallInst</tt>s and <tt>InvokeInst</tt>s the same way, even though their
				737	most-specific common base class is <tt>Instruction</tt>, which includes lots of
				738	less closely-related things. For these cases, LLVM provides a handy wrapper
				739	class called <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	740	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]	741	It is essentially a wrapper around an <tt>Instruction</tt> pointer, with some
				742	methods that provide functionality common to <tt>CallInst</tt>s and
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	743	<tt>InvokeInst</tt>s.</p>
				744
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	745	<p>This class has "value semantics": it should be passed by value, not by
				746	reference and it should not be dynamically allocated or deallocated using
				747	<tt>operator new</tt> or <tt>operator delete</tt>. It is efficiently copyable,
				748	assignable and constructable, with costs equivalents to that of a bare pointer.
				749	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]	750
				751	</div>
				752
Chris Lattner	1a3105b	2002-09-09 05:49:39 +0000	[diff] [blame]	753	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	754	<div class="doc_subsubsection">
				755	<a name="iterate_chains">Iterating over def-use & use-def chains</a>
				756	</div>
				757
				758	<div class="doc_text">
				759
				760	<p>Frequently, we might have an instance of the <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	761	href="/doxygen/structllvm_1_1Value.html">Value Class</a> and we want to
				762	determine which <tt>User</tt>s use the <tt>Value</tt>. The list of all
				763	<tt>User</tt>s of a particular <tt>Value</tt> is called a <i>def-use</i> chain.
				764	For example, let's say we have a <tt>Function*</tt> named <tt>F</tt> to a
				765	particular function <tt>foo</tt>. Finding all of the instructions that
				766	<i>use</i> <tt>foo</tt> is as simple as iterating over the <i>def-use</i> chain
				767	of <tt>F</tt>:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	768
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	769	<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]	770
				771	<p>Alternately, it's common to have an instance of the <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	772	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]	773	<tt>Value</tt>s are used by it. The list of all <tt>Value</tt>s used by a
				774	<tt>User</tt> is known as a <i>use-def</i> chain. Instances of class
				775	<tt>Instruction</tt> are common <tt>User</tt>s, so we might want to iterate over
				776	all of the values that a particular instruction uses (that is, the operands of
				777	the particular <tt>Instruction</tt>):</p>
				778
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	779	<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]	780
Chris Lattner	1a3105b	2002-09-09 05:49:39 +0000	[diff] [blame]	781	<!--
				782	def-use chains ("finding all users of"): Value::use_begin/use_end
				783	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]	784	-->
				785
				786	</div>
				787
				788	<!-- ======================================================================= -->
				789	<div class="doc_subsection">
				790	<a name="simplechanges">Making simple changes</a>
				791	</div>
				792
				793	<div class="doc_text">
				794
				795	<p>There are some primitive transformation operations present in the LLVM
Joel Stanley	753eb71	2002-09-11 22:32:24 +0000	[diff] [blame]	796	infrastructure that are worth knowing about. When performing
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	797	transformations, it's fairly common to manipulate the contents of basic
				798	blocks. This section describes some of the common methods for doing so
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	799	and gives example code.</p>
				800
				801	</div>
				802
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	803	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	804	<div class="doc_subsubsection">
				805	<a name="schanges_creating">Creating and inserting new
				806	<tt>Instruction</tt>s</a>
				807	</div>
				808
				809	<div class="doc_text">
				810
				811	<p><i>Instantiating Instructions</i></p>
				812
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	813	<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]	814	constructor for the kind of instruction to instantiate and provide the necessary
				815	parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> a
				816	(const-ptr-to) <tt>Type</tt>. Thus:</p>
				817
				818	<pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre>
				819
				820	<p>will create an <tt>AllocaInst</tt> instance that represents the allocation of
				821	one integer in the current stack frame, at runtime. Each <tt>Instruction</tt>
				822	subclass is likely to have varying default parameters which change the semantics
				823	of the instruction, so refer to the <a
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	824	href="/doxygen/classllvm_1_1Instruction.html">doxygen documentation for the subclass of
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	825	Instruction</a> that you're interested in instantiating.</p>
				826
				827	<p><i>Naming values</i></p>
				828
				829	<p>It is very useful to name the values of instructions when you're able to, as
				830	this facilitates the debugging of your transformations. If you end up looking
				831	at generated LLVM machine code, you definitely want to have logical names
				832	associated with the results of instructions! By supplying a value for the
				833	<tt>Name</tt> (default) parameter of the <tt>Instruction</tt> constructor, you
				834	associate a logical name with the result of the instruction's execution at
				835	runtime. For example, say that I'm writing a transformation that dynamically
				836	allocates space for an integer on the stack, and that integer is going to be
				837	used as some kind of index by some other code. To accomplish this, I place an
				838	<tt>AllocaInst</tt> at the first point in the first <tt>BasicBlock</tt> of some
				839	<tt>Function</tt>, and I'm intending to use it within the same
				840	<tt>Function</tt>. I might do:</p>
				841
				842	<pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre>
				843
				844	<p>where <tt>indexLoc</tt> is now the logical name of the instruction's
				845	execution value, which is a pointer to an integer on the runtime stack.</p>
				846
				847	<p><i>Inserting instructions</i></p>
				848
				849	<p>There are essentially two ways to insert an <tt>Instruction</tt>
				850	into an existing sequence of instructions that form a <tt>BasicBlock</tt>:</p>
				851
Joel Stanley	9dd1ad6	2002-09-18 03:17:23 +0000	[diff] [blame]	852	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	853	<li>Insertion into an explicit instruction list
				854
				855	<p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> within that
				856	<tt>BasicBlock</tt>, and a newly-created instruction we wish to insert
				857	before <tt>*pi</tt>, we do the following: </p>
				858
Alkis Evlogimenos	9a5dc4f	2004-05-27 00:57:51 +0000	[diff] [blame]	859	<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>
				860
				861	<p>Appending to the end of a <tt>BasicBlock</tt> is so common that
				862	the <tt>Instruction</tt> class and <tt>Instruction</tt>-derived
				863	classes provide constructors which take a pointer to a
				864	<tt>BasicBlock</tt> to be appended to. For example code that
				865	looked like: </p>
				866
				867	<pre> BasicBlock pb = ...;<br> Instruction newInst = new Instruction(...);<br> pb->getInstList().push_back(newInst); // appends newInst to pb<br></pre>
				868
				869	<p>becomes: </p>
				870
				871	<pre> BasicBlock pb = ...;<br> Instruction newInst = new Instruction(..., pb);<br></pre>
				872
				873	<p>which is much cleaner, especially if you are creating
				874	long instruction streams.</p></li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	875
				876	<li>Insertion into an implicit instruction list
				877
				878	<p><tt>Instruction</tt> instances that are already in <tt>BasicBlock</tt>s
				879	are implicitly associated with an existing instruction list: the instruction
				880	list of the enclosing basic block. Thus, we could have accomplished the same
				881	thing as the above code without being given a <tt>BasicBlock</tt> by doing:
				882	</p>
				883
				884	<pre> Instruction pi = ...;<br> Instruction newInst = new Instruction(...);<br> pi->getParent()->getInstList().insert(pi, newInst);<br></pre>
				885
				886	<p>In fact, this sequence of steps occurs so frequently that the
				887	<tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes provide
				888	constructors which take (as a default parameter) a pointer to an
				889	<tt>Instruction</tt> which the newly-created <tt>Instruction</tt> should
				890	precede. That is, <tt>Instruction</tt> constructors are capable of
				891	inserting the newly-created instance into the <tt>BasicBlock</tt> of a
				892	provided instruction, immediately before that instruction. Using an
				893	<tt>Instruction</tt> constructor with a <tt>insertBefore</tt> (default)
				894	parameter, the above code becomes:</p>
				895
				896	<pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre>
				897
				898	<p>which is much cleaner, especially if you're creating a lot of
				899	instructions and adding them to <tt>BasicBlock</tt>s.</p></li>
				900	</ul>
				901
				902	</div>
				903
				904	<!--_______________________________________________________________________-->
				905	<div class="doc_subsubsection">
				906	<a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a>
				907	</div>
				908
				909	<div class="doc_text">
				910
				911	<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]	912	<a href="#BasicBlock"><tt>BasicBlock</tt></a> is very straight-forward. First,
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	913	you must have a pointer to the instruction that you wish to delete. Second, you
				914	need to obtain the pointer to that instruction's basic block. You use the
				915	pointer to the basic block to get its list of instructions and then use the
				916	erase function to remove your instruction. For example:</p>
				917
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	918	<pre> <a href="#Instruction">Instruction</a> *I = .. ;<br> <a
				919	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]	920
				921	</div>
				922
				923	<!--_______________________________________________________________________-->
				924	<div class="doc_subsubsection">
				925	<a name="schanges_replacing">Replacing an <tt>Instruction</tt> with another
				926	<tt>Value</tt></a>
				927	</div>
				928
				929	<div class="doc_text">
				930
				931	<p><i>Replacing individual instructions</i></p>
				932
				933	<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]	934	permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	935	and <tt>ReplaceInstWithInst</tt>.</p>
				936
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	937	<h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	938
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	939	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	940	<li><tt>ReplaceInstWithValue</tt>
				941
				942	<p>This function replaces all uses (within a basic block) of a given
				943	instruction with a value, and then removes the original instruction. The
				944	following example illustrates the replacement of the result of a particular
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	945	<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]	946	pointer to an integer.</p>
				947
				948	<pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,<br> Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre></li>
				949
				950	<li><tt>ReplaceInstWithInst</tt>
				951
				952	<p>This function replaces a particular instruction with another
				953	instruction. The following example illustrates the replacement of one
				954	<tt>AllocaInst</tt> with another.</p>
				955
				956	<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]	957	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	958
				959	<p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p>
				960
				961	<p>You can use <tt>Value::replaceAllUsesWith</tt> and
				962	<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]	963	doxygen documentation for the <a href="/doxygen/structllvm_1_1Value.html">Value Class</a>
				964	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]	965	information.</p>
				966
				967	<!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out:
				968	include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with:
				969	ReplaceInstWithValue, ReplaceInstWithInst -->
				970
				971	</div>
				972
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	973	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	974	<div class="doc_section">
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	975	<a name="advanced">Advanced Topics</a>
				976	</div>
				977	<!-- *********************************************************************** -->
				978
				979	<div class="doc_text">
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	980	<p>
				981	This section describes some of the advanced or obscure API's that most clients
				982	do not need to be aware of. These API's tend manage the inner workings of the
				983	LLVM system, and only need to be accessed in unusual circumstances.
				984	</p>
				985	</div>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	986
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	987	<!-- ======================================================================= -->
				988	<div class="doc_subsection">
				989	<a name="TypeResolve">LLVM Type Resolution</a>
				990	</div>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	991
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	992	<div class="doc_text">
				993
				994	<p>
				995	The LLVM type system has a very simple goal: allow clients to compare types for
				996	structural equality with a simple pointer comparison (aka a shallow compare).
				997	This goal makes clients much simpler and faster, and is used throughout the LLVM
				998	system.
				999	</p>
				1000
				1001	<p>
				1002	Unfortunately achieving this goal is not a simple matter. In particular,
				1003	recursive types and late resolution of opaque types makes the situation very
				1004	difficult to handle. Fortunately, for the most part, our implementation makes
				1005	most clients able to be completely unaware of the nasty internal details. The
				1006	primary case where clients are exposed to the inner workings of it are when
				1007	building a recursive type. In addition to this case, the LLVM bytecode reader,
				1008	assembly parser, and linker also have to be aware of the inner workings of this
				1009	system.
				1010	</p>
				1011
Chris Lattner	0f876db	2005-04-25 15:47:57 +0000	[diff] [blame]	1012	<p>
				1013	For our purposes below, we need three concepts. First, an "Opaque Type" is
				1014	exactly as defined in the <a href="LangRef.html#t_opaque">language
				1015	reference</a>. Second an "Abstract Type" is any type which includes an
				1016	opaque type as part of its type graph (for example "<tt>{ opaque, int }</tt>").
				1017	Third, a concrete type is a type that is not an abstract type (e.g. "<tt>[ int,
				1018	float }</tt>").
				1019	</p>
				1020
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	1021	</div>
				1022
				1023	<!-- ______________________________________________________________________ -->
				1024	<div class="doc_subsubsection">
				1025	<a name="BuildRecType">Basic Recursive Type Construction</a>
				1026	</div>
				1027
				1028	<div class="doc_text">
				1029
				1030	<p>
				1031	Because the most common question is "how do I build a recursive type with LLVM",
				1032	we answer it now and explain it as we go. Here we include enough to cause this
				1033	to be emitted to an output .ll file:
				1034	</p>
				1035
				1036	<pre>
				1037	%mylist = type { %mylist*, int }
				1038	</pre>
				1039
				1040	<p>
				1041	To build this, use the following LLVM APIs:
				1042	</p>
				1043
				1044	<pre>
				1045	//<i> Create the initial outer struct.</i>
				1046	<a href="#PATypeHolder">PATypeHolder</a> StructTy = OpaqueType::get();
				1047	std::vector<const Type*> Elts;
				1048	Elts.push_back(PointerType::get(StructTy));
				1049	Elts.push_back(Type::IntTy);
				1050	StructType *NewSTy = StructType::get(Elts);
				1051
				1052	//<i> At this point, NewSTy = "{ opaque*, int }". Tell VMCore that</i>
				1053	//<i> the struct and the opaque type are actually the same.</i>
				1054	cast<OpaqueType>(StructTy.get())-><a href="#refineAbstractTypeTo">refineAbstractTypeTo</a>(NewSTy);
				1055
				1056	// <i>NewSTy is potentially invalidated, but StructTy (a <a href="#PATypeHolder">PATypeHolder</a>) is</i>
				1057	// <i>kept up-to-date.</i>
				1058	NewSTy = cast<StructType>(StructTy.get());
				1059
				1060	// <i>Add a name for the type to the module symbol table (optional).</i>
				1061	MyModule->addTypeName("mylist", NewSTy);
				1062	</pre>
				1063
				1064	<p>
				1065	This code shows the basic approach used to build recursive types: build a
				1066	non-recursive type using 'opaque', then use type unification to close the cycle.
				1067	The type unification step is performed by the <tt><a
				1068	ref="#refineAbstractTypeTo">refineAbstractTypeTo</a></tt> method, which is
				1069	described next. After that, we describe the <a
				1070	href="#PATypeHolder">PATypeHolder class</a>.
				1071	</p>
				1072
				1073	</div>
				1074
				1075	<!-- ______________________________________________________________________ -->
				1076	<div class="doc_subsubsection">
				1077	<a name="refineAbstractTypeTo">The <tt>refineAbstractTypeTo</tt> method</a>
				1078	</div>
				1079
				1080	<div class="doc_text">
				1081	<p>
				1082	The <tt>refineAbstractTypeTo</tt> method starts the type unification process.
				1083	While this method is actually a member of the DerivedType class, it is most
				1084	often used on OpaqueType instances. Type unification is actually a recursive
				1085	process. After unification, types can become structurally isomorphic to
				1086	existing types, and all duplicates are deleted (to preserve pointer equality).
				1087	</p>
				1088
				1089	<p>
				1090	In the example above, the OpaqueType object is definitely deleted.
				1091	Additionally, if there is an "{ \2*, int}" type already created in the system,
				1092	the pointer and struct type created are <b>also</b> deleted. Obviously whenever
				1093	a type is deleted, any "Type*" pointers in the program are invalidated. As
				1094	such, it is safest to avoid having <i>any</i> "Type*" pointers to abstract types
				1095	live across a call to <tt>refineAbstractTypeTo</tt> (note that non-abstract
				1096	types can never move or be deleted). To deal with this, the <a
				1097	href="#PATypeHolder">PATypeHolder</a> class is used to maintain a stable
				1098	reference to a possibly refined type, and the <a
				1099	href="#AbstractTypeUser">AbstractTypeUser</a> class is used to update more
				1100	complex datastructures.
				1101	</p>
				1102
				1103	</div>
				1104
				1105	<!-- ______________________________________________________________________ -->
				1106	<div class="doc_subsubsection">
				1107	<a name="PATypeHolder">The PATypeHolder Class</a>
				1108	</div>
				1109
				1110	<div class="doc_text">
				1111	<p>
				1112	PATypeHolder is a form of a "smart pointer" for Type objects. When VMCore
				1113	happily goes about nuking types that become isomorphic to existing types, it
				1114	automatically updates all PATypeHolder objects to point to the new type. In the
				1115	example above, this allows the code to maintain a pointer to the resultant
				1116	resolved recursive type, even though the Type*'s are potentially invalidated.
				1117	</p>
				1118
				1119	<p>
				1120	PATypeHolder is an extremely light-weight object that uses a lazy union-find
				1121	implementation to update pointers. For example the pointer from a Value to its
				1122	Type is maintained by PATypeHolder objects.
				1123	</p>
				1124
				1125	</div>
				1126
				1127	<!-- ______________________________________________________________________ -->
				1128	<div class="doc_subsubsection">
				1129	<a name="AbstractTypeUser">The AbstractTypeUser Class</a>
				1130	</div>
				1131
				1132	<div class="doc_text">
				1133
				1134	<p>
				1135	Some data structures need more to perform more complex updates when types get
				1136	resolved. The <a href="#SymbolTable">SymbolTable</a> class, for example, needs
				1137	move and potentially merge type planes in its representation when a pointer
				1138	changes.</p>
				1139
				1140	<p>
				1141	To support this, a class can derive from the AbstractTypeUser class. This class
				1142	allows it to get callbacks when certain types are resolved. To register to get
				1143	callbacks for a particular type, the DerivedType::{add/remove}AbstractTypeUser
Chris Lattner	0f876db	2005-04-25 15:47:57 +0000	[diff] [blame]	1144	methods can be called on a type. Note that these methods only work for <i>
				1145	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]	1146	somewhere) can never be refined.
				1147	</p>
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	1148	</div>
				1149
				1150
				1151	<!-- ======================================================================= -->
				1152	<div class="doc_subsection">
				1153	<a name="SymbolTable">The <tt>SymbolTable</tt> class</a>
				1154	</div>
Chris Lattner	f1b200b	2005-04-23 17:27:36 +0000	[diff] [blame]	1155
Chris Lattner	d9d6e10	2005-04-23 16:10:52 +0000	[diff] [blame]	1156	<div class="doc_text">
				1157	<p>This class provides a symbol table that the <a
				1158	href="#Function"><tt>Function</tt></a> and <a href="#Module">
				1159	<tt>Module</tt></a> classes use for naming definitions. The symbol table can
				1160	provide a name for any <a href="#Value"><tt>Value</tt></a> or <a
				1161	href="#Type"><tt>Type</tt></a>. <tt>SymbolTable</tt> is an abstract data
				1162	type. It hides the data it contains and provides access to it through a
				1163	controlled interface.</p>
				1164
				1165	<p>Note that the symbol table class is should not be directly accessed by most
				1166	clients. It should only be used when iteration over the symbol table names
				1167	themselves are required, which is very special purpose. Note that not all LLVM
				1168	<a href="#Value">Value</a>s have names, and those without names (i.e. they have
				1169	an empty name) do not exist in the symbol table.
				1170	</p>
				1171
				1172	<p>To use the <tt>SymbolTable</tt> well, you need to understand the
				1173	structure of the information it holds. The class contains two
				1174	<tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of
				1175	<tt>Type</tt> to maps of name (<tt>std::string</tt>) to <tt>Value</tt>.
				1176	The second, <tt>tmap</tt>, is a map of names to <tt>Type*</tt>. Thus, Values
				1177	are stored in two-dimensions and accessed by <tt>Type</tt> and name. Types,
				1178	however, are stored in a single dimension and accessed only by name.</p>
				1179
				1180	<p>The interface of this class provides three basic types of operations:
				1181	<ol>
				1182	<li><em>Accessors</em>. Accessors provide read-only access to information
				1183	such as finding a value for a name with the
				1184	<a href="#SymbolTable_lookup">lookup</a> method.</li>
				1185	<li><em>Mutators</em>. Mutators allow the user to add information to the
				1186	<tt>SymbolTable</tt> with methods like
				1187	<a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>
				1188	<li><em>Iterators</em>. Iterators allow the user to traverse the content
				1189	of the symbol table in well defined ways, such as the method
				1190	<a href="#SymbolTable_type_begin"><tt>type_begin</tt></a>.</li>
				1191	</ol>
				1192
				1193	<h3>Accessors</h3>
				1194	<dl>
				1195	<dt><tt>Value* lookup(const Type* Ty, const std::string& name) const</tt>:
				1196	</dt>
				1197	<dd>The <tt>lookup</tt> method searches the type plane given by the
				1198	<tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.
				1199	If a suitable <tt>Value</tt> is not found, null is returned.</dd>
				1200
				1201	<dt><tt>Type* lookupType( const std::string& name) const</tt>:</dt>
				1202	<dd>The <tt>lookupType</tt> method searches through the types for a
				1203	<tt>Type</tt> with the provided <tt>name</tt>. If a suitable <tt>Type</tt>
				1204	is not found, null is returned.</dd>
				1205
				1206	<dt><tt>bool hasTypes() const</tt>:</dt>
				1207	<dd>This function returns true if an entry has been made into the type
				1208	map.</dd>
				1209
				1210	<dt><tt>bool isEmpty() const</tt>:</dt>
				1211	<dd>This function returns true if both the value and types maps are
				1212	empty</dd>
				1213	</dl>
				1214
				1215	<h3>Mutators</h3>
				1216	<dl>
				1217	<dt><tt>void insert(Value *Val)</tt>:</dt>
				1218	<dd>This method adds the provided value to the symbol table. The Value must
				1219	have both a name and a type which are extracted and used to place the value
				1220	in the correct type plane under the value's name.</dd>
				1221
				1222	<dt><tt>void insert(const std::string& Name, Value *Val)</tt>:</dt>
				1223	<dd> Inserts a constant or type into the symbol table with the specified
				1224	name. There can be a many to one mapping between names and constants
				1225	or types.</dd>
				1226
				1227	<dt><tt>void insert(const std::string& Name, Type *Typ)</tt>:</dt>
				1228	<dd> Inserts a type into the symbol table with the specified name. There
				1229	can be a many-to-one mapping between names and types. This method
				1230	allows a type with an existing entry in the symbol table to get
				1231	a new name.</dd>
				1232
				1233	<dt><tt>void remove(Value* Val)</tt>:</dt>
				1234	<dd> This method removes a named value from the symbol table. The
				1235	type and name of the Value are extracted from \p N and used to
				1236	lookup the Value in the correct type plane. If the Value is
				1237	not in the symbol table, this method silently ignores the
				1238	request.</dd>
				1239
				1240	<dt><tt>void remove(Type* Typ)</tt>:</dt>
				1241	<dd> This method removes a named type from the symbol table. The
				1242	name of the type is extracted from \P T and used to look up
				1243	the Type in the type map. If the Type is not in the symbol
				1244	table, this method silently ignores the request.</dd>
				1245
				1246	<dt><tt>Value* remove(const std::string& Name, Value *Val)</tt>:</dt>
				1247	<dd> Remove a constant or type with the specified name from the
				1248	symbol table.</dd>
				1249
				1250	<dt><tt>Type* remove(const std::string& Name, Type* T)</tt>:</dt>
				1251	<dd> Remove a type with the specified name from the symbol table.
				1252	Returns the removed Type.</dd>
				1253
				1254	<dt><tt>Value *value_remove(const value_iterator& It)</tt>:</dt>
				1255	<dd> Removes a specific value from the symbol table.
				1256	Returns the removed value.</dd>
				1257
				1258	<dt><tt>bool strip()</tt>:</dt>
				1259	<dd> This method will strip the symbol table of its names leaving
				1260	the type and values. </dd>
				1261
				1262	<dt><tt>void clear()</tt>:</dt>
				1263	<dd>Empty the symbol table completely.</dd>
				1264	</dl>
				1265
				1266	<h3>Iteration</h3>
				1267	<p>The following functions describe three types of iterators you can obtain
				1268	the beginning or end of the sequence for both const and non-const. It is
				1269	important to keep track of the different kinds of iterators. There are
				1270	three idioms worth pointing out:</p>
				1271	<table>
				1272	<tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>
				1273	<tr>
				1274	<td align="left">Planes Of name/Value maps</td><td>PI</td>
				1275	<td align="left"><pre><tt>
				1276	for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),
				1277	PE = ST.plane_end(); PI != PE; ++PI ) {
				1278	PI->first // This is the Type* of the plane
				1279	PI->second // This is the SymbolTable::ValueMap of name/Value pairs
				1280	</tt></pre></td>
				1281	</tr>
				1282	<tr>
				1283	<td align="left">All name/Type Pairs</td><td>TI</td>
				1284	<td align="left"><pre><tt>
				1285	for (SymbolTable::type_const_iterator TI = ST.type_begin(),
				1286	TE = ST.type_end(); TI != TE; ++TI )
				1287	TI->first // This is the name of the type
				1288	TI->second // This is the Type* value associated with the name
				1289	</tt></pre></td>
				1290	</tr>
				1291	<tr>
				1292	<td align="left">name/Value pairs in a plane</td><td>VI</td>
				1293	<td align="left"><pre><tt>
				1294	for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),
				1295	VE = ST.value_end(SomeType); VI != VE; ++VI )
				1296	VI->first // This is the name of the Value
				1297	VI->second // This is the Value* value associated with the name
				1298	</tt></pre></td>
				1299	</tr>
				1300	</table>
				1301
				1302	<p>Using the recommended iterator names and idioms will help you avoid
				1303	making mistakes. Of particular note, make sure that whenever you use
				1304	value_begin(SomeType) that you always compare the resulting iterator
				1305	with value_end(SomeType) not value_end(SomeOtherType) or else you
				1306	will loop infinitely.</p>
				1307
				1308	<dl>
				1309
				1310	<dt><tt>plane_iterator plane_begin()</tt>:</dt>
				1311	<dd>Get an iterator that starts at the beginning of the type planes.
				1312	The iterator will iterate over the Type/ValueMap pairs in the
				1313	type planes. </dd>
				1314
				1315	<dt><tt>plane_const_iterator plane_begin() const</tt>:</dt>
				1316	<dd>Get a const_iterator that starts at the beginning of the type
				1317	planes. The iterator will iterate over the Type/ValueMap pairs
				1318	in the type planes. </dd>
				1319
				1320	<dt><tt>plane_iterator plane_end()</tt>:</dt>
				1321	<dd>Get an iterator at the end of the type planes. This serves as
				1322	the marker for end of iteration over the type planes.</dd>
				1323
				1324	<dt><tt>plane_const_iterator plane_end() const</tt>:</dt>
				1325	<dd>Get a const_iterator at the end of the type planes. This serves as
				1326	the marker for end of iteration over the type planes.</dd>
				1327
				1328	<dt><tt>value_iterator value_begin(const Type *Typ)</tt>:</dt>
				1329	<dd>Get an iterator that starts at the beginning of a type plane.
				1330	The iterator will iterate over the name/value pairs in the type plane.
				1331	Note: The type plane must already exist before using this.</dd>
				1332
				1333	<dt><tt>value_const_iterator value_begin(const Type *Typ) const</tt>:</dt>
				1334	<dd>Get a const_iterator that starts at the beginning of a type plane.
				1335	The iterator will iterate over the name/value pairs in the type plane.
				1336	Note: The type plane must already exist before using this.</dd>
				1337
				1338	<dt><tt>value_iterator value_end(const Type *Typ)</tt>:</dt>
				1339	<dd>Get an iterator to the end of a type plane. This serves as the marker
				1340	for end of iteration of the type plane.
				1341	Note: The type plane must already exist before using this.</dd>
				1342
				1343	<dt><tt>value_const_iterator value_end(const Type *Typ) const</tt>:</dt>
				1344	<dd>Get a const_iterator to the end of a type plane. This serves as the
				1345	marker for end of iteration of the type plane.
				1346	Note: the type plane must already exist before using this.</dd>
				1347
				1348	<dt><tt>type_iterator type_begin()</tt>:</dt>
				1349	<dd>Get an iterator to the start of the name/Type map.</dd>
				1350
				1351	<dt><tt>type_const_iterator type_begin() cons</tt>:</dt>
				1352	<dd> Get a const_iterator to the start of the name/Type map.</dd>
				1353
				1354	<dt><tt>type_iterator type_end()</tt>:</dt>
				1355	<dd>Get an iterator to the end of the name/Type map. This serves as the
				1356	marker for end of iteration of the types.</dd>
				1357
				1358	<dt><tt>type_const_iterator type_end() const</tt>:</dt>
				1359	<dd>Get a const-iterator to the end of the name/Type map. This serves
				1360	as the marker for end of iteration of the types.</dd>
				1361
				1362	<dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>
				1363	<dd>This method returns a plane_const_iterator for iteration over
				1364	the type planes starting at a specific plane, given by \p Ty.</dd>
				1365
				1366	<dt><tt>plane_iterator find( const Type* Typ </tt>:</dt>
				1367	<dd>This method returns a plane_iterator for iteration over the
				1368	type planes starting at a specific plane, given by \p Ty.</dd>
				1369
				1370	</dl>
				1371	</div>
				1372
				1373
				1374
				1375	<!-- *********************************************************************** -->
				1376	<div class="doc_section">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1377	<a name="coreclasses">The Core LLVM Class Hierarchy Reference </a>
				1378	</div>
				1379	<!-- *********************************************************************** -->
				1380
				1381	<div class="doc_text">
				1382
				1383	<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]	1384	being inspected or transformed. The core LLVM classes are defined in
				1385	header files in the <tt>include/llvm/</tt> directory, and implemented in
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1386	the <tt>lib/VMCore</tt> directory.</p>
				1387
				1388	</div>
				1389
				1390	<!-- ======================================================================= -->
				1391	<div class="doc_subsection">
				1392	<a name="Value">The <tt>Value</tt> class</a>
				1393	</div>
				1394
				1395	<div>
				1396
				1397	<p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>
				1398	<br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1399	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]	1400
				1401	<p>The <tt>Value</tt> class is the most important class in the LLVM Source
				1402	base. It represents a typed value that may be used (among other things) as an
				1403	operand to an instruction. There are many different types of <tt>Value</tt>s,
				1404	such as <a href="#Constant"><tt>Constant</tt></a>s,<a
				1405	href="#Argument"><tt>Argument</tt></a>s. Even <a
				1406	href="#Instruction"><tt>Instruction</tt></a>s and <a
				1407	href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p>
				1408
				1409	<p>A particular <tt>Value</tt> may be used many times in the LLVM representation
				1410	for a program. For example, an incoming argument to a function (represented
				1411	with an instance of the <a href="#Argument">Argument</a> class) is "used" by
				1412	every instruction in the function that references the argument. To keep track
				1413	of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
				1414	href="#User"><tt>User</tt></a>s that is using it (the <a
				1415	href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
				1416	graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
				1417	def-use information in the program, and is accessible through the <tt>use_</tt>*
				1418	methods, shown below.</p>
				1419
				1420	<p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed,
				1421	and this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
				1422	method. In addition, all LLVM values can be named. The "name" of the
				1423	<tt>Value</tt> is a symbolic string printed in the LLVM code:</p>
				1424
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1425	<pre> %<b>foo</b> = add int 1, 2<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1426
				1427	<p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>
				1428	that the name of any value may be missing (an empty string), so names should
				1429	<b>ONLY</b> be used for debugging (making the source code easier to read,
				1430	debugging printouts), they should not be used to keep track of values or map
				1431	between them. For this purpose, use a <tt>std::map</tt> of pointers to the
				1432	<tt>Value</tt> itself instead.</p>
				1433
				1434	<p>One important aspect of LLVM is that there is no distinction between an SSA
				1435	variable and the operation that produces it. Because of this, any reference to
				1436	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]	1437	argument, for example) is represented as a direct pointer to the instance of
				1438	the class that
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1439	represents this value. Although this may take some getting used to, it
				1440	simplifies the representation and makes it easier to manipulate.</p>
				1441
				1442	</div>
				1443
				1444	<!-- _______________________________________________________________________ -->
				1445	<div class="doc_subsubsection">
				1446	<a name="m_Value">Important Public Members of the <tt>Value</tt> class</a>
				1447	</div>
				1448
				1449	<div class="doc_text">
				1450
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1451	<ul>
				1452	<li><tt>Value::use_iterator</tt> - Typedef for iterator over the
				1453	use-list<br>
				1454	<tt>Value::use_const_iterator</tt> - Typedef for const_iterator over
				1455	the use-list<br>
				1456	<tt>unsigned use_size()</tt> - Returns the number of users of the
				1457	value.<br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1458	<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]	1459	<tt>use_iterator use_begin()</tt> - Get an iterator to the start of
				1460	the use-list.<br>
				1461	<tt>use_iterator use_end()</tt> - Get an iterator to the end of the
				1462	use-list.<br>
				1463	<tt><a href="#User">User</a> *use_back()</tt> - Returns the last
				1464	element in the list.
				1465	<p> These methods are the interface to access the def-use
				1466	information in LLVM. As with all other iterators in LLVM, the naming
				1467	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]	1468	</li>
				1469	<li><tt><a href="#Type">Type</a> *getType() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1470	<p>This method returns the Type of the Value.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1471	</li>
				1472	<li><tt>bool hasName() const</tt><br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1473	<tt>std::string getName() const</tt><br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1474	<tt>void setName(const std::string &Name)</tt>
				1475	<p> This family of methods is used to access and assign a name to a <tt>Value</tt>,
				1476	be aware of the <a href="#nameWarning">precaution above</a>.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1477	</li>
				1478	<li><tt>void replaceAllUsesWith(Value *V)</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1479
				1480	<p>This method traverses the use list of a <tt>Value</tt> changing all <a
				1481	href="#User"><tt>User</tt>s</a> of the current value to refer to
				1482	"<tt>V</tt>" instead. For example, if you detect that an instruction always
				1483	produces a constant value (for example through constant folding), you can
				1484	replace all uses of the instruction with the constant like this:</p>
				1485
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1486	<pre> Inst->replaceAllUsesWith(ConstVal);<br></pre>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1487	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1488
				1489	</div>
				1490
				1491	<!-- ======================================================================= -->
				1492	<div class="doc_subsection">
				1493	<a name="User">The <tt>User</tt> class</a>
				1494	</div>
				1495
				1496	<div class="doc_text">
				1497
				1498	<p>
				1499	<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]	1500	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]	1501	Superclass: <a href="#Value"><tt>Value</tt></a></p>
				1502
				1503	<p>The <tt>User</tt> class is the common base class of all LLVM nodes that may
				1504	refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
				1505	that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
				1506	referring to. The <tt>User</tt> class itself is a subclass of
				1507	<tt>Value</tt>.</p>
				1508
				1509	<p>The operands of a <tt>User</tt> point directly to the LLVM <a
				1510	href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
				1511	Single Assignment (SSA) form, there can only be one definition referred to,
				1512	allowing this direct connection. This connection provides the use-def
				1513	information in LLVM.</p>
				1514
				1515	</div>
				1516
				1517	<!-- _______________________________________________________________________ -->
				1518	<div class="doc_subsubsection">
				1519	<a name="m_User">Important Public Members of the <tt>User</tt> class</a>
				1520	</div>
				1521
				1522	<div class="doc_text">
				1523
				1524	<p>The <tt>User</tt> class exposes the operand list in two ways: through
				1525	an index access interface and through an iterator based interface.</p>
				1526
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1527	<ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1528	<li><tt>Value *getOperand(unsigned i)</tt><br>
				1529	<tt>unsigned getNumOperands()</tt>
				1530	<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]	1531	convenient form for direct access.</p></li>
				1532
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1533	<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand
				1534	list<br>
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	1535	<tt>op_iterator op_begin()</tt> - Get an iterator to the start of
				1536	the operand list.<br>
				1537	<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]	1538	operand list.
				1539	<p> Together, these methods make up the iterator based interface to
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1540	the operands of a <tt>User</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1541	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1542
				1543	</div>
				1544
				1545	<!-- ======================================================================= -->
				1546	<div class="doc_subsection">
				1547	<a name="Instruction">The <tt>Instruction</tt> class</a>
				1548	</div>
				1549
				1550	<div class="doc_text">
				1551
				1552	<p><tt>#include "</tt><tt><a
				1553	href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt><br>
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	1554	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]	1555	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				1556	href="#Value"><tt>Value</tt></a></p>
				1557
				1558	<p>The <tt>Instruction</tt> class is the common base class for all LLVM
				1559	instructions. It provides only a few methods, but is a very commonly used
				1560	class. The primary data tracked by the <tt>Instruction</tt> class itself is the
				1561	opcode (instruction type) and the parent <a
				1562	href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
				1563	into. To represent a specific type of instruction, one of many subclasses of
				1564	<tt>Instruction</tt> are used.</p>
				1565
				1566	<p> Because the <tt>Instruction</tt> class subclasses the <a
				1567	href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
				1568	way as for other <a href="#User"><tt>User</tt></a>s (with the
				1569	<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
				1570	<tt>op_begin()</tt>/<tt>op_end()</tt> methods).</p> <p> An important file for
				1571	the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> file. This
				1572	file contains some meta-data about the various different types of instructions
				1573	in LLVM. It describes the enum values that are used as opcodes (for example
				1574	<tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), as well as the
				1575	concrete sub-classes of <tt>Instruction</tt> that implement the instruction (for
				1576	example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a
				1577	href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, the use of macros in
				1578	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]	1579	<a href="/doxygen/classllvm_1_1Instruction.html">doxygen output</a>.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1580
				1581	</div>
				1582
				1583	<!-- _______________________________________________________________________ -->
				1584	<div class="doc_subsubsection">
				1585	<a name="m_Instruction">Important Public Members of the <tt>Instruction</tt>
				1586	class</a>
				1587	</div>
				1588
				1589	<div class="doc_text">
				1590
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1591	<ul>
				1592	<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1593	<p>Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that
				1594	this <tt>Instruction</tt> is embedded into.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1595	<li><tt>bool mayWriteToMemory()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1596	<p>Returns true if the instruction writes to memory, i.e. it is a
				1597	<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]	1598	<li><tt>unsigned getOpcode()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1599	<p>Returns the opcode for the <tt>Instruction</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1600	<li><tt><a href="#Instruction">Instruction</a> *clone() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1601	<p>Returns another instance of the specified instruction, identical
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1602	in all ways to the original except that the instruction has no parent
				1603	(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]	1604	and it has no name</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1605	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1606
				1607	</div>
				1608
				1609	<!-- ======================================================================= -->
				1610	<div class="doc_subsection">
				1611	<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
				1612	</div>
				1613
				1614	<div class="doc_text">
				1615
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1616	<p><tt>#include "<a
				1617	href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br>
				1618	doxygen info: <a href="/doxygen/structllvm_1_1BasicBlock.html">BasicBlock
				1619	Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1620	Superclass: <a href="#Value"><tt>Value</tt></a></p>
				1621
				1622	<p>This class represents a single entry multiple exit section of the code,
				1623	commonly known as a basic block by the compiler community. The
				1624	<tt>BasicBlock</tt> class maintains a list of <a
				1625	href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block.
				1626	Matching the language definition, the last element of this list of instructions
				1627	is always a terminator instruction (a subclass of the <a
				1628	href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p>
				1629
				1630	<p>In addition to tracking the list of instructions that make up the block, the
				1631	<tt>BasicBlock</tt> class also keeps track of the <a
				1632	href="#Function"><tt>Function</tt></a> that it is embedded into.</p>
				1633
				1634	<p>Note that <tt>BasicBlock</tt>s themselves are <a
				1635	href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
				1636	like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
				1637	<tt>label</tt>.</p>
				1638
				1639	</div>
				1640
				1641	<!-- _______________________________________________________________________ -->
				1642	<div class="doc_subsubsection">
				1643	<a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt>
				1644	class</a>
				1645	</div>
				1646
				1647	<div class="doc_text">
				1648
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1649	<ul>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1650
				1651	<li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1652	href="#Function">Function</a> *Parent = 0)</tt>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1653
				1654	<p>The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
				1655	insertion into a function. The constructor optionally takes a name for the new
				1656	block, and a <a href="#Function"><tt>Function</tt></a> to insert it into. If
				1657	the <tt>Parent</tt> parameter is specified, the new <tt>BasicBlock</tt> is
				1658	automatically inserted at the end of the specified <a
				1659	href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
				1660	manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p></li>
				1661
				1662	<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
				1663	<tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
				1664	<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1665	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1666	STL-style functions for accessing the instruction list.
				1667
				1668	<p>These methods and typedefs are forwarding functions that have the same
				1669	semantics as the standard library methods of the same names. These methods
				1670	expose the underlying instruction list of a basic block in a way that is easy to
				1671	manipulate. To get the full complement of container operations (including
				1672	operations to update the list), you must use the <tt>getInstList()</tt>
				1673	method.</p></li>
				1674
				1675	<li><tt>BasicBlock::InstListType &getInstList()</tt>
				1676
				1677	<p>This method is used to get access to the underlying container that actually
				1678	holds the Instructions. This method must be used when there isn't a forwarding
				1679	function in the <tt>BasicBlock</tt> class for the operation that you would like
				1680	to perform. Because there are no forwarding functions for "updating"
				1681	operations, you need to use this if you want to update the contents of a
				1682	<tt>BasicBlock</tt>.</p></li>
				1683
				1684	<li><tt><a href="#Function">Function</a> *getParent()</tt>
				1685
				1686	<p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
				1687	embedded into, or a null pointer if it is homeless.</p></li>
				1688
				1689	<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt>
				1690
				1691	<p> Returns a pointer to the terminator instruction that appears at the end of
				1692	the <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
				1693	instruction in the block is not a terminator, then a null pointer is
				1694	returned.</p></li>
				1695
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1696	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1697
				1698	</div>
				1699
				1700	<!-- ======================================================================= -->
				1701	<div class="doc_subsection">
				1702	<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
				1703	</div>
				1704
				1705	<div class="doc_text">
				1706
				1707	<p><tt>#include "<a
				1708	href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1709	doxygen info: <a href="/doxygen/classllvm_1_1GlobalValue.html">GlobalValue
				1710	Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1711	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				1712	href="#Value"><tt>Value</tt></a></p>
				1713
				1714	<p>Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
				1715	href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
				1716	visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
				1717	Because they are visible at global scope, they are also subject to linking with
				1718	other globals defined in different translation units. To control the linking
				1719	process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
				1720	<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]	1721	defined by the <tt>LinkageTypes</tt> enumeration.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1722
				1723	<p>If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
				1724	<tt>static</tt> in C), it is not visible to code outside the current translation
				1725	unit, and does not participate in linking. If it has external linkage, it is
				1726	visible to external code, and does participate in linking. In addition to
				1727	linkage information, <tt>GlobalValue</tt>s keep track of which <a
				1728	href="#Module"><tt>Module</tt></a> they are currently part of.</p>
				1729
				1730	<p>Because <tt>GlobalValue</tt>s are memory objects, they are always referred to
				1731	by their <b>address</b>. As such, the <a href="#Type"><tt>Type</tt></a> of a
				1732	global is always a pointer to its contents. It is important to remember this
				1733	when using the <tt>GetElementPtrInst</tt> instruction because this pointer must
				1734	be dereferenced first. For example, if you have a <tt>GlobalVariable</tt> (a
				1735	subclass of <tt>GlobalValue)</tt> that is an array of 24 ints, type <tt>[24 x
				1736	int]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although
				1737	the address of the first element of this array and the value of the
				1738	<tt>GlobalVariable</tt> are the same, they have different types. The
				1739	<tt>GlobalVariable</tt>'s type is <tt>[24 x int]</tt>. The first element's type
				1740	is <tt>int.</tt> Because of this, accessing a global value requires you to
				1741	dereference the pointer with <tt>GetElementPtrInst</tt> first, then its elements
				1742	can be accessed. This is explained in the <a href="LangRef.html#globalvars">LLVM
				1743	Language Reference Manual</a>.</p>
				1744
				1745	</div>
				1746
				1747	<!-- _______________________________________________________________________ -->
				1748	<div class="doc_subsubsection">
				1749	<a name="m_GlobalValue">Important Public Members of the <tt>GlobalValue</tt>
				1750	class</a>
				1751	</div>
				1752
				1753	<div class="doc_text">
				1754
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1755	<ul>
				1756	<li><tt>bool hasInternalLinkage() const</tt><br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1757	<tt>bool hasExternalLinkage() const</tt><br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1758	<tt>void setInternalLinkage(bool HasInternalLinkage)</tt>
				1759	<p> These methods manipulate the linkage characteristics of the <tt>GlobalValue</tt>.</p>
				1760	<p> </p>
				1761	</li>
				1762	<li><tt><a href="#Module">Module</a> *getParent()</tt>
				1763	<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]	1764	GlobalValue is currently embedded into.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1765	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1766
				1767	</div>
				1768
				1769	<!-- ======================================================================= -->
				1770	<div class="doc_subsection">
				1771	<a name="Function">The <tt>Function</tt> class</a>
				1772	</div>
				1773
				1774	<div class="doc_text">
				1775
				1776	<p><tt>#include "<a
				1777	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]	1778	info: <a href="/doxygen/classllvm_1_1Function.html">Function Class</a><br>
				1779	Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1780	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
				1781
				1782	<p>The <tt>Function</tt> class represents a single procedure in LLVM. It is
				1783	actually one of the more complex classes in the LLVM heirarchy because it must
				1784	keep track of a large amount of data. The <tt>Function</tt> class keeps track
				1785	of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
				1786	href="#Argument"><tt>Argument</tt></a>s, and a <a
				1787	href="#SymbolTable"><tt>SymbolTable</tt></a>.</p>
				1788
				1789	<p>The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most
				1790	commonly used part of <tt>Function</tt> objects. The list imposes an implicit
				1791	ordering of the blocks in the function, which indicate how the code will be
				1792	layed out by the backend. Additionally, the first <a
				1793	href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
				1794	<tt>Function</tt>. It is not legal in LLVM to explicitly branch to this initial
				1795	block. There are no implicit exit nodes, and in fact there may be multiple exit
				1796	nodes from a single <tt>Function</tt>. If the <a
				1797	href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
				1798	the <tt>Function</tt> is actually a function declaration: the actual body of the
				1799	function hasn't been linked in yet.</p>
				1800
				1801	<p>In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
				1802	<tt>Function</tt> class also keeps track of the list of formal <a
				1803	href="#Argument"><tt>Argument</tt></a>s that the function receives. This
				1804	container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
				1805	nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
				1806	the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.</p>
				1807
				1808	<p>The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used
				1809	LLVM feature that is only used when you have to look up a value by name. Aside
				1810	from that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used
				1811	internally to make sure that there are not conflicts between the names of <a
				1812	href="#Instruction"><tt>Instruction</tt></a>s, <a
				1813	href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
				1814	href="#Argument"><tt>Argument</tt></a>s in the function body.</p>
				1815
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	1816	<p>Note that <tt>Function</tt> is a <a href="#GlobalValue">GlobalValue</a>
				1817	and therefore also a <a href="#Constant">Constant</a>. The value of the function
				1818	is its address (after linking) which is guaranteed to be constant.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1819	</div>
				1820
				1821	<!-- _______________________________________________________________________ -->
				1822	<div class="doc_subsubsection">
				1823	<a name="m_Function">Important Public Members of the <tt>Function</tt>
				1824	class</a>
				1825	</div>
				1826
				1827	<div class="doc_text">
				1828
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1829	<ul>
				1830	<li><tt>Function(const </tt><tt><a href="#FunctionType">FunctionType</a>
Chris Lattner	ac479e5	2004-08-04 05:10:48 +0000	[diff] [blame]	1831	Ty, LinkageTypes Linkage, const std::string &N = "", Module Parent = 0)</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1832
				1833	<p>Constructor used when you need to create new <tt>Function</tt>s to add
				1834	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]	1835	create and what type of linkage the function should have. The <a
				1836	href="#FunctionType"><tt>FunctionType</tt></a> argument
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1837	specifies the formal arguments and return value for the function. The same
				1838	<a href="#FunctionTypel"><tt>FunctionType</tt></a> value can be used to
				1839	create multiple functions. The <tt>Parent</tt> argument specifies the Module
				1840	in which the function is defined. If this argument is provided, the function
				1841	will automatically be inserted into that module's list of
				1842	functions.</p></li>
				1843
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1844	<li><tt>bool isExternal()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1845
				1846	<p>Return whether or not the <tt>Function</tt> has a body defined. If the
				1847	function is "external", it does not have a body, and thus must be resolved
				1848	by linking with a function defined in a different translation unit.</p></li>
				1849
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1850	<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1851	<tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1852
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1853	<tt>begin()</tt>, <tt>end()</tt>
				1854	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1855
				1856	<p>These are forwarding methods that make it easy to access the contents of
				1857	a <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
				1858	list.</p></li>
				1859
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1860	<li><tt>Function::BasicBlockListType &getBasicBlockList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1861
				1862	<p>Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This
				1863	is necessary to use when you need to update the list or perform a complex
				1864	action that doesn't have a forwarding method.</p></li>
				1865
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1866	<li><tt>Function::arg_iterator</tt> - Typedef for the argument list
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1867	iterator<br>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1868	<tt>Function::const_arg_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1869
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1870	<tt>arg_begin()</tt>, <tt>arg_end()</tt>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1871	<tt>arg_size()</tt>, <tt>arg_empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1872
				1873	<p>These are forwarding methods that make it easy to access the contents of
				1874	a <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a>
				1875	list.</p></li>
				1876
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1877	<li><tt>Function::ArgumentListType &getArgumentList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1878
				1879	<p>Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
				1880	necessary to use when you need to update the list or perform a complex
				1881	action that doesn't have a forwarding method.</p></li>
				1882
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1883	<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryBlock()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1884
				1885	<p>Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
				1886	function. Because the entry block for the function is always the first
				1887	block, this returns the first block of the <tt>Function</tt>.</p></li>
				1888
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1889	<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
				1890	<tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1891
				1892	<p>This traverses the <a href="#Type"><tt>Type</tt></a> of the
				1893	<tt>Function</tt> and returns the return type of the function, or the <a
				1894	href="#FunctionType"><tt>FunctionType</tt></a> of the actual
				1895	function.</p></li>
				1896
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1897	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1898
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1899	<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]	1900	for this <tt>Function</tt>.</p></li>
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
				1903	</div>
				1904
				1905	<!-- ======================================================================= -->
				1906	<div class="doc_subsection">
				1907	<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
				1908	</div>
				1909
				1910	<div class="doc_text">
				1911
				1912	<p><tt>#include "<a
				1913	href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt>
				1914	<br>
Tanya Lattner	a3da777	2004-06-22 08:02:25 +0000	[diff] [blame]	1915	doxygen info: <a href="/doxygen/classllvm_1_1GlobalVariable.html">GlobalVariable
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1916	Class</a><br> Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
				1917	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
				1918
				1919	<p>Global variables are represented with the (suprise suprise)
				1920	<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are also
				1921	subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are
				1922	always referenced by their address (global values must live in memory, so their
				1923	"name" refers to their address). See <a
				1924	href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global variables
				1925	may have an initial value (which must be a <a
				1926	href="#Constant"><tt>Constant</tt></a>), and if they have an initializer, they
				1927	may be marked as "constant" themselves (indicating that their contents never
				1928	change at runtime).</p>
				1929
				1930	</div>
				1931
				1932	<!-- _______________________________________________________________________ -->
				1933	<div class="doc_subsubsection">
				1934	<a name="m_GlobalVariable">Important Public Members of the
				1935	<tt>GlobalVariable</tt> class</a>
				1936	</div>
				1937
				1938	<div class="doc_text">
				1939
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1940	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1941	<li><tt>GlobalVariable(const </tt><tt><a href="#Type">Type</a> *Ty, bool
				1942	isConstant, LinkageTypes& Linkage, <a href="#Constant">Constant</a>
				1943	Initializer = 0, const std::string &Name = "", Module Parent = 0)</tt>
				1944
				1945	<p>Create a new global variable of the specified type. If
				1946	<tt>isConstant</tt> is true then the global variable will be marked as
				1947	unchanging for the program. The Linkage parameter specifies the type of
				1948	linkage (internal, external, weak, linkonce, appending) for the variable. If
				1949	the linkage is InternalLinkage, WeakLinkage, or LinkOnceLinkage,  then
				1950	the resultant global variable will have internal linkage. AppendingLinkage
				1951	concatenates together all instances (in different translation units) of the
				1952	variable into a single variable but is only applicable to arrays.  See
				1953	the <a href="LangRef.html#modulestructure">LLVM Language Reference</a> for
				1954	further details on linkage types. Optionally an initializer, a name, and the
				1955	module to put the variable into may be specified for the global variable as
				1956	well.</p></li>
				1957
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1958	<li><tt>bool isConstant() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1959
				1960	<p>Returns true if this is a global variable that is known not to
				1961	be modified at runtime.</p></li>
				1962
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1963	<li><tt>bool hasInitializer()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1964
				1965	<p>Returns true if this <tt>GlobalVariable</tt> has an intializer.</p></li>
				1966
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1967	<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1968
				1969	<p>Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal
				1970	to call this method if there is no initializer.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1971	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1972
				1973	</div>
				1974
				1975	<!-- ======================================================================= -->
				1976	<div class="doc_subsection">
				1977	<a name="Module">The <tt>Module</tt> class</a>
				1978	</div>
				1979
				1980	<div class="doc_text">
				1981
				1982	<p><tt>#include "<a
				1983	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]	1984	<a href="/doxygen/classllvm_1_1Module.html">Module Class</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1985
				1986	<p>The <tt>Module</tt> class represents the top level structure present in LLVM
				1987	programs. An LLVM module is effectively either a translation unit of the
				1988	original program or a combination of several translation units merged by the
				1989	linker. The <tt>Module</tt> class keeps track of a list of <a
				1990	href="#Function"><tt>Function</tt></a>s, a list of <a
				1991	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
				1992	href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
				1993	helpful member functions that try to make common operations easy.</p>
				1994
				1995	</div>
				1996
				1997	<!-- _______________________________________________________________________ -->
				1998	<div class="doc_subsubsection">
				1999	<a name="m_Module">Important Public Members of the <tt>Module</tt> class</a>
				2000	</div>
				2001
				2002	<div class="doc_text">
				2003
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2004	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2005	<li><tt>Module::Module(std::string name = "")</tt></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2006	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2007
				2008	<p>Constructing a <a href="#Module">Module</a> is easy. You can optionally
				2009	provide a name for it (probably based on the name of the translation unit).</p>
				2010
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2011	<ul>
				2012	<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	2013	<tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2014
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	2015	<tt>begin()</tt>, <tt>end()</tt>
				2016	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2017
				2018	<p>These are forwarding methods that make it easy to access the contents of
				2019	a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
				2020	list.</p></li>
				2021
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2022	<li><tt>Module::FunctionListType &getFunctionList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2023
				2024	<p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
				2025	necessary to use when you need to update the list or perform a complex
				2026	action that doesn't have a forwarding method.</p>
				2027
				2028	<p><!-- Global Variable --></p></li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2029	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2030
				2031	<hr>
				2032
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2033	<ul>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	2034	<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]	2035
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	2036	<tt>Module::const_global_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2037
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	2038	<tt>global_begin()</tt>, <tt>global_end()</tt>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	2039	<tt>global_size()</tt>, <tt>global_empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2040
				2041	<p> These are forwarding methods that make it easy to access the contents of
				2042	a <tt>Module</tt> object's <a
				2043	href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li>
				2044
				2045	<li><tt>Module::GlobalListType &getGlobalList()</tt>
				2046
				2047	<p>Returns the list of <a
				2048	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. This is necessary to
				2049	use when you need to update the list or perform a complex action that
				2050	doesn't have a forwarding method.</p>
				2051
				2052	<p><!-- Symbol table stuff --> </p></li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2053	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2054
				2055	<hr>
				2056
				2057	<ul>
				2058	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
				2059
				2060	<p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
				2061	for this <tt>Module</tt>.</p>
				2062
				2063	<p><!-- Convenience methods --></p></li>
				2064	</ul>
				2065
				2066	<hr>
				2067
				2068	<ul>
				2069	<li><tt><a href="#Function">Function</a> *getFunction(const std::string
				2070	&Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt>
				2071
				2072	<p>Look up the specified function in the <tt>Module</tt> <a
				2073	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
				2074	<tt>null</tt>.</p></li>
				2075
				2076	<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const
				2077	std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt>
				2078
				2079	<p>Look up the specified function in the <tt>Module</tt> <a
				2080	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
				2081	external declaration for the function and return it.</p></li>
				2082
				2083	<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt>
				2084
				2085	<p>If there is at least one entry in the <a
				2086	href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
				2087	href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
				2088	string.</p></li>
				2089
				2090	<li><tt>bool addTypeName(const std::string &Name, const <a
				2091	href="#Type">Type</a> *Ty)</tt>
				2092
				2093	<p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
				2094	mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this
				2095	name, true is returned and the <a
				2096	href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li>
				2097	</ul>
				2098
				2099	</div>
				2100
				2101	<!-- ======================================================================= -->
				2102	<div class="doc_subsection">
				2103	<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
				2104	</div>
				2105
				2106	<div class="doc_text">
				2107
				2108	<p>Constant represents a base class for different types of constants. It
				2109	is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
				2110	ConstantArray etc for representing the various types of Constants.</p>
				2111
				2112	</div>
				2113
				2114	<!-- _______________________________________________________________________ -->
				2115	<div class="doc_subsubsection">
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2116	<a name="m_Constant">Important Public Methods</a>
				2117	</div>
				2118	<div class="doc_text">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2119	</div>
				2120
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2121	<!-- _______________________________________________________________________ -->
				2122	<div class="doc_subsubsection">Important Subclasses of Constant </div>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2123	<div class="doc_text">
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2124	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2125	<li>ConstantSInt : This subclass of Constant represents a signed integer
				2126	constant.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2127	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2128	<li><tt>int64_t getValue() const</tt>: Returns the underlying value of
				2129	this constant. </li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2130	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2131	</li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2132	<li>ConstantUInt : This class represents an unsigned integer.
				2133	<ul>
				2134	<li><tt>uint64_t getValue() const</tt>: Returns the underlying value of
				2135	this constant. </li>
				2136	</ul>
				2137	</li>
				2138	<li>ConstantFP : This class represents a floating point constant.
				2139	<ul>
				2140	<li><tt>double getValue() const</tt>: Returns the underlying value of
				2141	this constant. </li>
				2142	</ul>
				2143	</li>
				2144	<li>ConstantBool : This represents a boolean constant.
				2145	<ul>
				2146	<li><tt>bool getValue() const</tt>: Returns the underlying value of this
				2147	constant. </li>
				2148	</ul>
				2149	</li>
				2150	<li>ConstantArray : This represents a constant array.
				2151	<ul>
				2152	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	2153	a vector of component constants that makeup this array. </li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2154	</ul>
				2155	</li>
				2156	<li>ConstantStruct : This represents a constant struct.
				2157	<ul>
				2158	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	2159	a vector of component constants that makeup this array. </li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	2160	</ul>
				2161	</li>
				2162	<li>GlobalValue : This represents either a global variable or a function. In
				2163	either case, the value is a constant fixed address (after linking).
				2164	</li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2165	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2166	</div>
				2167
				2168	<!-- ======================================================================= -->
				2169	<div class="doc_subsection">
				2170	<a name="Type">The <tt>Type</tt> class and Derived Types</a>
				2171	</div>
				2172
				2173	<div class="doc_text">
				2174
				2175	<p>Type as noted earlier is also a subclass of a Value class. Any primitive
				2176	type (like int, short etc) in LLVM is an instance of Type Class. All other
				2177	types are instances of subclasses of type like FunctionType, ArrayType
				2178	etc. DerivedType is the interface for all such dervied types including
				2179	FunctionType, ArrayType, PointerType, StructType. Types can have names. They can
				2180	be recursive (StructType). There exists exactly one instance of any type
				2181	structure at a time. This allows using pointer equality of Type *s for comparing
				2182	types.</p>
				2183
				2184	</div>
				2185
				2186	<!-- _______________________________________________________________________ -->
				2187	<div class="doc_subsubsection">
				2188	<a name="m_Value">Important Public Methods</a>
				2189	</div>
				2190
				2191	<div class="doc_text">
				2192
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2193	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2194
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2195	<li><tt>bool isSigned() const</tt>: Returns whether an integral numeric type
				2196	is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is
				2197	not true for Float and Double. </li>
				2198
				2199	<li><tt>bool isUnsigned() const</tt>: Returns whether a numeric type is
				2200	unsigned. This is not quite the complement of isSigned... nonnumeric types
				2201	return false as they do with isSigned. This returns true for UByteTy,
				2202	UShortTy, UIntTy, and ULongTy. </li>
				2203
Chris Lattner	4573f1b	2004-07-08 17:49:37 +0000	[diff] [blame]	2204	<li><tt>bool isInteger() const</tt>: Equivalent to isSigned() \|\| isUnsigned().</li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2205
				2206	<li><tt>bool isIntegral() const</tt>: Returns true if this is an integral
				2207	type, which is either Bool type or one of the Integer types.</li>
				2208
				2209	<li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two
				2210	floating point types.</li>
				2211
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2212	<li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if
				2213	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]	2214	example, uint to int or one pointer type to another.</li>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	2215	</ul>
				2216	</div>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2217
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	2218	<!-- _______________________________________________________________________ -->
				2219	<div class="doc_subsubsection">
				2220	<a name="m_Value">Important Derived Types</a>
				2221	</div>
				2222	<div class="doc_text">
				2223	<ul>
				2224	<li>SequentialType : This is subclassed by ArrayType and PointerType
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2225	<ul>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	2226	<li><tt>const Type * getElementType() const</tt>: Returns the type of each
				2227	of the elements in the sequential type. </li>
				2228	</ul>
				2229	</li>
				2230	<li>ArrayType : This is a subclass of SequentialType and defines interface for
				2231	array types.
				2232	<ul>
				2233	<li><tt>unsigned getNumElements() const</tt>: Returns the number of
				2234	elements in the array. </li>
				2235	</ul>
				2236	</li>
				2237	<li>PointerType : Subclass of SequentialType for pointer types. </li>
				2238	<li>StructType : subclass of DerivedTypes for struct types </li>
				2239	<li>FunctionType : subclass of DerivedTypes for function types.
				2240	<ul>
				2241	<li><tt>bool isVarArg() const</tt>: Returns true if its a vararg
				2242	function</li>
				2243	<li><tt> const Type * getReturnType() const</tt>: Returns the
				2244	return type of the function.</li>
				2245	<li><tt>const Type * getParamType (unsigned i)</tt>: Returns
				2246	the type of the ith parameter.</li>
				2247	<li><tt> const unsigned getNumParams() const</tt>: Returns the
				2248	number of formal parameters.</li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2249	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2250	</li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	2251	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2252	</div>
				2253
				2254	<!-- ======================================================================= -->
				2255	<div class="doc_subsection">
				2256	<a name="Argument">The <tt>Argument</tt> class</a>
				2257	</div>
				2258
				2259	<div class="doc_text">
				2260
				2261	<p>This subclass of Value defines the interface for incoming formal
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	2262	arguments to a function. A Function maintains a list of its formal
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2263	arguments. An argument has a pointer to the parent Function.</p>
				2264
				2265	</div>
				2266
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	2267	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2268	<hr>
				2269	<address>
				2270	<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
				2271	src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
				2272	<a href="http://validator.w3.org/check/referer"><img
				2273	src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
				2274
				2275	<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
				2276	<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
				2277	<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
				2278	Last modified: $Date$
				2279	</address>
				2280
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2281	</body>
				2282	</html>