Blame - docs/ProgrammersManual.html - fp2-dev/platform/external/llvm

blob: eb3bde98a8bef86e9b88a7507226fcd67af46487 [file] [log] [blame]

Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
				2	"http://www.w3.org/TR/html4/strict.dtd">
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	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	44	</ul>
				45	</li>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	46	<li><a href="#common">Helpful Hints for Common Operations</a>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	47	<ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	48	<li><a href="#inspection">Basic Inspection and Traversal Routines</a>
				49	<ul>
				50	<li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
				51	in a <tt>Function</tt></a> </li>
				52	<li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
				53	in a <tt>BasicBlock</tt></a> </li>
				54	<li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
				55	in a <tt>Function</tt></a> </li>
				56	<li><a href="#iterate_convert">Turning an iterator into a
				57	class pointer</a> </li>
				58	<li><a href="#iterate_complex">Finding call sites: a more
				59	complex example</a> </li>
				60	<li><a href="#calls_and_invokes">Treating calls and invokes
				61	the same way</a> </li>
				62	<li><a href="#iterate_chains">Iterating over def-use &
				63	use-def chains</a> </li>
				64	</ul>
				65	</li>
				66	<li><a href="#simplechanges">Making simple changes</a>
				67	<ul>
				68	<li><a href="#schanges_creating">Creating and inserting new
				69	<tt>Instruction</tt>s</a> </li>
				70	<li><a href="#schanges_deleting">Deleting <tt>Instruction</tt>s</a> </li>
				71	<li><a href="#schanges_replacing">Replacing an <tt>Instruction</tt>
				72	with another <tt>Value</tt></a> </li>
				73	</ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	74	</li>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	75	<!--
				76	<li>Working with the Control Flow Graph
				77	<ul>
				78	<li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
				79	<li>
				80	<li>
				81	</ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	82	-->
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	83	</ul>
				84	</li>
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	85	<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	86	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	87	<li><a href="#Value">The <tt>Value</tt> class</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	88	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	89	<li><a href="#User">The <tt>User</tt> class</a>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	90	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	91	<li><a href="#Instruction">The <tt>Instruction</tt> class</a>
				92	<ul>
				93	<li><a href="#GetElementPtrInst">The <tt>GetElementPtrInst</tt> class</a></li>
				94	</ul>
				95	</li>
				96	<li><a href="#Module">The <tt>Module</tt> class</a></li>
				97	<li><a href="#Constant">The <tt>Constant</tt> class</a>
				98	<ul>
				99	<li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
				100	<ul>
				101	<li><a href="#BasicBlock">The <tt>BasicBlock</tt>class</a></li>
				102	<li><a href="#Function">The <tt>Function</tt> class</a></li>
				103	<li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a></li>
				104	</ul>
				105	</li>
				106	</ul>
				107	</li>
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	108	</ul>
				109	</li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	110	<li><a href="#Type">The <tt>Type</tt> class</a> </li>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	111	<li><a href="#Argument">The <tt>Argument</tt> class</a></li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	112	</ul>
				113	</li>
				114	</ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	115	</li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	116	<li><a href="#SymbolTable">The <tt>SymbolTable</tt> class </a></li>
				117	<li>The <tt>ilist</tt> and <tt>iplist</tt> classes
				118	<ul>
				119	<li>Creating, inserting, moving and deleting from LLVM lists </li>
				120	</ul>
				121	</li>
				122	<li>Important iterator invalidation semantics to be aware of.</li>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	123	</ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	124
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	125	<div class="doc_author">
				126	<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
Chris Lattner	94c4359	2004-05-26 16:52:55 +0000	[diff] [blame]	127	<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>,
				128	<a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a>, and
				129	<a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	130	</div>
				131
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	132	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	133	<div class="doc_section">
				134	<a name="introduction">Introduction </a>
				135	</div>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	136	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	137
				138	<div class="doc_text">
				139
				140	<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]	141	interfaces available in the LLVM source-base. This manual is not
				142	intended to explain what LLVM is, how it works, and what LLVM code looks
				143	like. It assumes that you know the basics of LLVM and are interested
				144	in writing transformations or otherwise analyzing or manipulating the
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	145	code.</p>
				146
				147	<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]	148	way in the continuously growing source code that makes up the LLVM
				149	infrastructure. Note that this manual is not intended to serve as a
				150	replacement for reading the source code, so if you think there should be
				151	a method in one of these classes to do something, but it's not listed,
				152	check the source. Links to the <a href="/doxygen/">doxygen</a> sources
				153	are provided to make this as easy as possible.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	154
				155	<p>The first section of this document describes general information that is
				156	useful to know when working in the LLVM infrastructure, and the second describes
				157	the Core LLVM classes. In the future this manual will be extended with
				158	information describing how to use extension libraries, such as dominator
				159	information, CFG traversal routines, and useful utilities like the <tt><a
				160	href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.</p>
				161
				162	</div>
				163
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	164	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	165	<div class="doc_section">
				166	<a name="general">General Information</a>
				167	</div>
				168	<!-- *********************************************************************** -->
				169
				170	<div class="doc_text">
				171
				172	<p>This section contains general information that is useful if you are working
				173	in the LLVM source-base, but that isn't specific to any particular API.</p>
				174
				175	</div>
				176
				177	<!-- ======================================================================= -->
				178	<div class="doc_subsection">
				179	<a name="stl">The C++ Standard Template Library</a>
				180	</div>
				181
				182	<div class="doc_text">
				183
				184	<p>LLVM makes heavy use of the C++ Standard Template Library (STL),
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	185	perhaps much more than you are used to, or have seen before. Because of
				186	this, you might want to do a little background reading in the
				187	techniques used and capabilities of the library. There are many good
				188	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]	189	can get, so it will not be discussed in this document.</p>
				190
				191	<p>Here are some useful links:</p>
				192
				193	<ol>
				194
				195	<li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++ Library
				196	reference</a> - an excellent reference for the STL and other parts of the
				197	standard C++ library.</li>
				198
				199	<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]	200	O'Reilly book in the making. It has a decent
				201	Standard Library
				202	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]	203	published.</li>
				204
				205	<li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
				206	Questions</a></li>
				207
				208	<li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
				209	Contains a useful <a
				210	href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
				211	STL</a>.</li>
				212
				213	<li><a href="http://www.research.att.com/%7Ebs/C++.html">Bjarne Stroustrup's C++
				214	Page</a></li>
				215
Tanya Lattner	79445ba	2004-12-08 18:34:56 +0000	[diff] [blame]	216	<li><a href="http://64.78.49.204/">
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	217	Bruce Eckel's Thinking in C++, 2nd ed. Volume 2 Revision 4.0 (even better, get
				218	the book).</a></li>
				219
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	220	</ol>
				221
				222	<p>You are also encouraged to take a look at the <a
				223	href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
				224	to write maintainable code more than where to put your curly braces.</p>
				225
				226	</div>
				227
				228	<!-- ======================================================================= -->
				229	<div class="doc_subsection">
				230	<a name="stl">Other useful references</a>
				231	</div>
				232
				233	<div class="doc_text">
				234
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	235	<ol>
				236	<li><a href="http://www.psc.edu/%7Esemke/cvs_branches.html">CVS
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	237	Branch and Tag Primer</a></li>
Misha Brukman	a0f71e4	2004-06-18 18:39:00 +0000	[diff] [blame]	238	<li><a href="http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html">Using
				239	static and shared libraries across platforms</a></li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	240	</ol>
				241
				242	</div>
				243
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	244	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	245	<div class="doc_section">
				246	<a name="apis">Important and useful LLVM APIs</a>
				247	</div>
				248	<!-- *********************************************************************** -->
				249
				250	<div class="doc_text">
				251
				252	<p>Here we highlight some LLVM APIs that are generally useful and good to
				253	know about when writing transformations.</p>
				254
				255	</div>
				256
				257	<!-- ======================================================================= -->
				258	<div class="doc_subsection">
				259	<a name="isa">The isa<>, cast<> and dyn_cast<> templates</a>
				260	</div>
				261
				262	<div class="doc_text">
				263
				264	<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]	265	These templates have many similarities to the C++ <tt>dynamic_cast<></tt>
				266	operator, but they don't have some drawbacks (primarily stemming from
				267	the fact that <tt>dynamic_cast<></tt> only works on classes that
				268	have a v-table). Because they are used so often, you must know what they
				269	do and how they work. All of these templates are defined in the <a
				270	href="/doxygen/Casting_8h-source.html"><tt>Support/Casting.h</tt></a>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	271	file (note that you very rarely have to include this file directly).</p>
				272
				273	<dl>
				274	<dt><tt>isa<></tt>: </dt>
				275
				276	<dd>The <tt>isa<></tt> operator works exactly like the Java
				277	"<tt>instanceof</tt>" operator. It returns true or false depending on whether
				278	a reference or pointer points to an instance of the specified class. This can
				279	be very useful for constraint checking of various sorts (example below).</dd>
				280
				281	<dt><tt>cast<></tt>: </dt>
				282
				283	<dd>The <tt>cast<></tt> operator is a "checked cast" operation. It
				284	converts a pointer or reference from a base class to a derived cast, causing
				285	an assertion failure if it is not really an instance of the right type. This
				286	should be used in cases where you have some information that makes you believe
				287	that something is of the right type. An example of the <tt>isa<></tt>
				288	and <tt>cast<></tt> template is:
				289
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	290	<pre>
				291	static bool isLoopInvariant(const <a href="#Value">Value</a> V, const Loop L) {
				292	if (isa<<a href="#Constant">Constant</a>>(V) \|\| isa<<a href="#Argument">Argument</a>>(V) \|\| isa<<a href="#GlobalValue">GlobalValue</a>>(V))
				293	return true;
				294
Chris Lattner	53f72b3	2005-04-22 04:49:59 +0000	[diff] [blame^]	295	<i>// Otherwise, it must be an instruction...</i>
				296	return !L->contains(cast<<a href="#Instruction">Instruction</a>>(V)->getParent());
				297	}
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	298	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	299
				300	<p>Note that you should <b>not</b> use an <tt>isa<></tt> test followed
				301	by a <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt>
				302	operator.</p>
				303
				304	</dd>
				305
				306	<dt><tt>dyn_cast<></tt>:</dt>
				307
				308	<dd>The <tt>dyn_cast<></tt> operator is a "checking cast" operation. It
				309	checks to see if the operand is of the specified type, and if so, returns a
				310	pointer to it (this operator does not work with references). If the operand is
				311	not of the correct type, a null pointer is returned. Thus, this works very
				312	much like the <tt>dynamic_cast</tt> operator in C++, and should be used in the
				313	same circumstances. Typically, the <tt>dyn_cast<></tt> operator is used
				314	in an <tt>if</tt> statement or some other flow control statement like this:
				315
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	316	<pre>
				317	if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a href="#AllocationInst">AllocationInst</a>>(Val)) {
				318	...
				319	}
				320	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	321
				322	<p> This form of the <tt>if</tt> statement effectively combines together a
				323	call to <tt>isa<></tt> and a call to <tt>cast<></tt> into one
				324	statement, which is very convenient.</p>
				325
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	326	<p>Note that the <tt>dyn_cast<></tt> operator, like C++'s
				327	<tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused.
				328	In particular you should not use big chained <tt>if/then/else</tt> blocks to
				329	check for lots of different variants of classes. If you find yourself
				330	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^]	331	<tt>InstVisitor</tt> class to dispatch over the instruction type directly.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	332
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	333	</dd>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	334
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	335	<dt><tt>cast_or_null<></tt>: </dt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	336
				337	<dd>The <tt>cast_or_null<></tt> operator works just like the
				338	<tt>cast<></tt> operator, except that it allows for a null pointer as
				339	an argument (which it then propagates). This can sometimes be useful,
				340	allowing you to combine several null checks into one.</dd>
				341
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	342	<dt><tt>dyn_cast_or_null<></tt>: </dt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	343
				344	<dd>The <tt>dyn_cast_or_null<></tt> operator works just like the
				345	<tt>dyn_cast<></tt> operator, except that it allows for a null pointer
				346	as an argument (which it then propagates). This can sometimes be useful,
				347	allowing you to combine several null checks into one.</dd>
				348
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	349	</dl>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	350
				351	<p>These five templates can be used with any classes, whether they have a
				352	v-table or not. To add support for these templates, you simply need to add
				353	<tt>classof</tt> static methods to the class you are interested casting
				354	to. Describing this is currently outside the scope of this document, but there
				355	are lots of examples in the LLVM source base.</p>
				356
				357	</div>
				358
				359	<!-- ======================================================================= -->
				360	<div class="doc_subsection">
				361	<a name="DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> option</a>
				362	</div>
				363
				364	<div class="doc_text">
				365
				366	<p>Often when working on your pass you will put a bunch of debugging printouts
				367	and other code into your pass. After you get it working, you want to remove
				368	it... but you may need it again in the future (to work out new bugs that you run
				369	across).</p>
				370
				371	<p> Naturally, because of this, you don't want to delete the debug printouts,
				372	but you don't want them to always be noisy. A standard compromise is to comment
				373	them out, allowing you to enable them if you need them in the future.</p>
				374
				375	<p>The "<tt><a href="/doxygen/Debug_8h-source.html">Support/Debug.h</a></tt>"
				376	file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to
				377	this problem. Basically, you can put arbitrary code into the argument of the
				378	<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other
				379	tool) is run with the '<tt>-debug</tt>' command line argument:</p>
				380
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	381	<pre> ... <br> DEBUG(std::cerr << "I am here!\n");<br> ...<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	382
				383	<p>Then you can run your pass like this:</p>
				384
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	385	<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]	386
				387	<p>Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you
				388	to not have to create "yet another" command line option for the debug output for
				389	your pass. Note that <tt>DEBUG()</tt> macros are disabled for optimized builds,
				390	so they do not cause a performance impact at all (for the same reason, they
				391	should also not contain side-effects!).</p>
				392
				393	<p>One additional nice thing about the <tt>DEBUG()</tt> macro is that you can
				394	enable or disable it directly in gdb. Just use "<tt>set DebugFlag=0</tt>" or
				395	"<tt>set DebugFlag=1</tt>" from the gdb if the program is running. If the
				396	program hasn't been started yet, you can always just run it with
				397	<tt>-debug</tt>.</p>
				398
				399	</div>
				400
				401	<!-- _______________________________________________________________________ -->
				402	<div class="doc_subsubsection">
				403	<a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE()</tt> and
				404	the <tt>-debug-only</tt> option</a>
				405	</div>
				406
				407	<div class="doc_text">
				408
				409	<p>Sometimes you may find yourself in a situation where enabling <tt>-debug</tt>
				410	just turns on <b>too much</b> information (such as when working on the code
				411	generator). If you want to enable debug information with more fine-grained
				412	control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only
				413	option as follows:</p>
				414
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	415	<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]	416
				417	<p>Then you can run your pass like this:</p>
				418
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	419	<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]	420
				421	<p>Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of
				422	a file, to specify the debug type for the entire module (if you do this before
				423	you <tt>#include "Support/Debug.h"</tt>, you don't have to insert the ugly
				424	<tt>#undef</tt>'s). Also, you should use names more meaningful than "foo" and
				425	"bar", because there is no system in place to ensure that names do not
				426	conflict. If two different modules use the same string, they will all be turned
				427	on when the name is specified. This allows, for example, all debug information
				428	for instruction scheduling to be enabled with <tt>-debug-type=InstrSched</tt>,
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	429	even if the source lives in multiple files.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	430
				431	</div>
				432
				433	<!-- ======================================================================= -->
				434	<div class="doc_subsection">
				435	<a name="Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt>
				436	option</a>
				437	</div>
				438
				439	<div class="doc_text">
				440
				441	<p>The "<tt><a
				442	href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>" file
				443	provides a template named <tt>Statistic</tt> that is used as a unified way to
				444	keep track of what the LLVM compiler is doing and how effective various
				445	optimizations are. It is useful to see what optimizations are contributing to
				446	making a particular program run faster.</p>
				447
				448	<p>Often you may run your pass on some big program, and you're interested to see
				449	how many times it makes a certain transformation. Although you can do this with
				450	hand inspection, or some ad-hoc method, this is a real pain and not very useful
				451	for big programs. Using the <tt>Statistic</tt> template makes it very easy to
				452	keep track of this information, and the calculated information is presented in a
				453	uniform manner with the rest of the passes being executed.</p>
				454
				455	<p>There are many examples of <tt>Statistic</tt> uses, but the basics of using
				456	it are as follows:</p>
				457
				458	<ol>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	459	<li>Define your statistic like this:
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	460	<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]	461
				462	<p>The <tt>Statistic</tt> template can emulate just about any data-type,
				463	but if you do not specify a template argument, it defaults to acting like
				464	an unsigned int counter (this is usually what you want).</p></li>
				465
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	466	<li>Whenever you make a transformation, bump the counter:
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	467	<pre> ++NumXForms; // I did stuff<br></pre>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	468	</li>
				469	</ol>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	470
				471	<p>That's all you have to do. To get '<tt>opt</tt>' to print out the
				472	statistics gathered, use the '<tt>-stats</tt>' option:</p>
				473
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	474	<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]	475
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	476	<p> When running <tt>gccas</tt> on a C file from the SPEC benchmark
				477	suite, it gives a report that looks like this:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	478
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	479	<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]	480
				481	<p>Obviously, with so many optimizations, having a unified framework for this
				482	stuff is very nice. Making your pass fit well into the framework makes it more
				483	maintainable and useful.</p>
				484
				485	</div>
				486
				487	<!-- *********************************************************************** -->
				488	<div class="doc_section">
				489	<a name="common">Helpful Hints for Common Operations</a>
				490	</div>
				491	<!-- *********************************************************************** -->
				492
				493	<div class="doc_text">
				494
				495	<p>This section describes how to perform some very simple transformations of
				496	LLVM code. This is meant to give examples of common idioms used, showing the
				497	practical side of LLVM transformations. <p> Because this is a "how-to" section,
				498	you should also read about the main classes that you will be working with. The
				499	<a href="#coreclasses">Core LLVM Class Hierarchy Reference</a> contains details
				500	and descriptions of the main classes that you should know about.</p>
				501
				502	</div>
				503
				504	<!-- NOTE: this section should be heavy on example code -->
				505	<!-- ======================================================================= -->
				506	<div class="doc_subsection">
				507	<a name="inspection">Basic Inspection and Traversal Routines</a>
				508	</div>
				509
				510	<div class="doc_text">
				511
				512	<p>The LLVM compiler infrastructure have many different data structures that may
				513	be traversed. Following the example of the C++ standard template library, the
				514	techniques used to traverse these various data structures are all basically the
				515	same. For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or
				516	method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt>
				517	function returns an iterator pointing to one past the last valid element of the
				518	sequence, and there is some <tt>XXXiterator</tt> data type that is common
				519	between the two operations.</p>
				520
				521	<p>Because the pattern for iteration is common across many different aspects of
				522	the program representation, the standard template library algorithms may be used
				523	on them, and it is easier to remember how to iterate. First we show a few common
				524	examples of the data structures that need to be traversed. Other data
				525	structures are traversed in very similar ways.</p>
				526
				527	</div>
				528
				529	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	530	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	531	<a name="iterate_function">Iterating over the </a><a
				532	href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a
				533	href="#Function"><tt>Function</tt></a>
				534	</div>
				535
				536	<div class="doc_text">
				537
				538	<p>It's quite common to have a <tt>Function</tt> instance that you'd like to
				539	transform in some way; in particular, you'd like to manipulate its
				540	<tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over all of
				541	the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>. The following is
				542	an example that prints the name of a <tt>BasicBlock</tt> and the number of
				543	<tt>Instruction</tt>s it contains:</p>
				544
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	545	<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]	546
				547	<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]	548	invoking member functions of the <tt>Instruction</tt> class. This is
				549	because the indirection operator is overloaded for the iterator
Chris Lattner	7496ec5	2003-08-05 22:54:23 +0000	[diff] [blame]	550	classes. In the above code, the expression <tt>i->size()</tt> is
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	551	exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.</p>
				552
				553	</div>
				554
				555	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	556	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	557	<a name="iterate_basicblock">Iterating over the </a><a
				558	href="#Instruction"><tt>Instruction</tt></a>s in a <a
				559	href="#BasicBlock"><tt>BasicBlock</tt></a>
				560	</div>
				561
				562	<div class="doc_text">
				563
				564	<p>Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, it's
				565	easy to iterate over the individual instructions that make up
				566	<tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in
				567	a <tt>BasicBlock</tt>:</p>
				568
Chris Lattner	55c0461	2005-03-06 06:00:13 +0000	[diff] [blame]	569	<pre>
				570	// blk is a pointer to a BasicBlock instance
				571	for (BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)
				572	// the next statement works since operator<<(ostream&,...)
				573	// is overloaded for Instruction&
				574	std::cerr << *i << "\n";
				575	</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	576
				577	<p>However, this isn't really the best way to print out the contents of a
				578	<tt>BasicBlock</tt>! Since the ostream operators are overloaded for virtually
				579	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]	580	basic block itself: <tt>std::cerr << *blk << "\n";</tt>.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	581
				582	</div>
				583
				584	<!-- _______________________________________________________________________ -->
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	585	<div class="doc_subsubsection">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	586	<a name="iterate_institer">Iterating over the </a><a
				587	href="#Instruction"><tt>Instruction</tt></a>s in a <a
				588	href="#Function"><tt>Function</tt></a>
				589	</div>
				590
				591	<div class="doc_text">
				592
				593	<p>If you're finding that you commonly iterate over a <tt>Function</tt>'s
				594	<tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s <tt>Instruction</tt>s,
				595	<tt>InstIterator</tt> should be used instead. You'll need to include <a
				596	href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>,
				597	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]	598	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]	599
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	600	<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]	601	Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
				602	worklist with its initial contents. For example, if you wanted to
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	603	initialize a worklist to contain all instructions in a <tt>Function</tt>
				604	F, all you would need to do is something like:
				605	<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]	606
				607	<p>The STL set <tt>worklist</tt> would now contain all instructions in the
				608	<tt>Function</tt> pointed to by F.</p>
				609
				610	</div>
				611
				612	<!-- _______________________________________________________________________ -->
				613	<div class="doc_subsubsection">
				614	<a name="iterate_convert">Turning an iterator into a class pointer (and
				615	vice-versa)</a>
				616	</div>
				617
				618	<div class="doc_text">
				619
				620	<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]	621	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]	622	a reference or a pointer from an iterator is very straight-forward.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	623	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]	624	is a <tt>BasicBlock::const_iterator</tt>:</p>
				625
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	626	<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]	627
				628	<p>However, the iterators you'll be working with in the LLVM framework are
				629	special: they will automatically convert to a ptr-to-instance type whenever they
				630	need to. Instead of dereferencing the iterator and then taking the address of
				631	the result, you can simply assign the iterator to the proper pointer type and
				632	you get the dereference and address-of operation as a result of the assignment
				633	(behind the scenes, this is a result of overloading casting mechanisms). Thus
				634	the last line of the last example,</p>
				635
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	636	<pre>Instruction* pinst = &*i;</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	637
				638	<p>is semantically equivalent to</p>
				639
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	640	<pre>Instruction* pinst = i;</pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	641
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	642	<p>It's also possible to turn a class pointer into the corresponding iterator,
				643	and this is a constant time operation (very efficient). The following code
				644	snippet illustrates use of the conversion constructors provided by LLVM
				645	iterators. By using these, you can explicitly grab the iterator of something
				646	without actually obtaining it via iteration over some structure:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	647
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	648	<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]	649
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	650	</div>
				651
				652	<!--_______________________________________________________________________-->
				653	<div class="doc_subsubsection">
				654	<a name="iterate_complex">Finding call sites: a slightly more complex
				655	example</a>
				656	</div>
				657
				658	<div class="doc_text">
				659
				660	<p>Say that you're writing a FunctionPass and would like to count all the
				661	locations in the entire module (that is, across every <tt>Function</tt>) where a
				662	certain function (i.e., some <tt>Function</tt>*) is already in scope. As you'll
				663	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]	664	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]	665	you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this
				666	is what we want to do:</p>
				667
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	668	<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]	669
				670	<p>And the actual code is (remember, since we're writing a
				671	<tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply has to
				672	override the <tt>runOnFunction</tt> method...):</p>
				673
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	674	<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
				675	href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a
				676	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]	677
				678	</div>
				679
Brian Gaeke	f1972c6	2003-11-07 19:25:45 +0000	[diff] [blame]	680	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	681	<div class="doc_subsubsection">
				682	<a name="calls_and_invokes">Treating calls and invokes the same way</a>
				683	</div>
				684
				685	<div class="doc_text">
				686
				687	<p>You may have noticed that the previous example was a bit oversimplified in
				688	that it did not deal with call sites generated by 'invoke' instructions. In
				689	this, and in other situations, you may find that you want to treat
				690	<tt>CallInst</tt>s and <tt>InvokeInst</tt>s the same way, even though their
				691	most-specific common base class is <tt>Instruction</tt>, which includes lots of
				692	less closely-related things. For these cases, LLVM provides a handy wrapper
				693	class called <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	694	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]	695	It is essentially a wrapper around an <tt>Instruction</tt> pointer, with some
				696	methods that provide functionality common to <tt>CallInst</tt>s and
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	697	<tt>InvokeInst</tt>s.</p>
				698
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	699	<p>This class has "value semantics": it should be passed by value, not by
				700	reference and it should not be dynamically allocated or deallocated using
				701	<tt>operator new</tt> or <tt>operator delete</tt>. It is efficiently copyable,
				702	assignable and constructable, with costs equivalents to that of a bare pointer.
				703	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]	704
				705	</div>
				706
Chris Lattner	1a3105b	2002-09-09 05:49:39 +0000	[diff] [blame]	707	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	708	<div class="doc_subsubsection">
				709	<a name="iterate_chains">Iterating over def-use & use-def chains</a>
				710	</div>
				711
				712	<div class="doc_text">
				713
				714	<p>Frequently, we might have an instance of the <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	715	href="/doxygen/structllvm_1_1Value.html">Value Class</a> and we want to
				716	determine which <tt>User</tt>s use the <tt>Value</tt>. The list of all
				717	<tt>User</tt>s of a particular <tt>Value</tt> is called a <i>def-use</i> chain.
				718	For example, let's say we have a <tt>Function*</tt> named <tt>F</tt> to a
				719	particular function <tt>foo</tt>. Finding all of the instructions that
				720	<i>use</i> <tt>foo</tt> is as simple as iterating over the <i>def-use</i> chain
				721	of <tt>F</tt>:</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	722
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	723	<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]	724
				725	<p>Alternately, it's common to have an instance of the <a
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	726	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]	727	<tt>Value</tt>s are used by it. The list of all <tt>Value</tt>s used by a
				728	<tt>User</tt> is known as a <i>use-def</i> chain. Instances of class
				729	<tt>Instruction</tt> are common <tt>User</tt>s, so we might want to iterate over
				730	all of the values that a particular instruction uses (that is, the operands of
				731	the particular <tt>Instruction</tt>):</p>
				732
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	733	<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]	734
Chris Lattner	1a3105b	2002-09-09 05:49:39 +0000	[diff] [blame]	735	<!--
				736	def-use chains ("finding all users of"): Value::use_begin/use_end
				737	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]	738	-->
				739
				740	</div>
				741
				742	<!-- ======================================================================= -->
				743	<div class="doc_subsection">
				744	<a name="simplechanges">Making simple changes</a>
				745	</div>
				746
				747	<div class="doc_text">
				748
				749	<p>There are some primitive transformation operations present in the LLVM
Joel Stanley	753eb71	2002-09-11 22:32:24 +0000	[diff] [blame]	750	infrastructure that are worth knowing about. When performing
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	751	transformations, it's fairly common to manipulate the contents of basic
				752	blocks. This section describes some of the common methods for doing so
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	753	and gives example code.</p>
				754
				755	</div>
				756
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	757	<!--_______________________________________________________________________-->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	758	<div class="doc_subsubsection">
				759	<a name="schanges_creating">Creating and inserting new
				760	<tt>Instruction</tt>s</a>
				761	</div>
				762
				763	<div class="doc_text">
				764
				765	<p><i>Instantiating Instructions</i></p>
				766
Chris Lattner	69bf8a9	2004-05-23 21:06:58 +0000	[diff] [blame]	767	<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]	768	constructor for the kind of instruction to instantiate and provide the necessary
				769	parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> a
				770	(const-ptr-to) <tt>Type</tt>. Thus:</p>
				771
				772	<pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre>
				773
				774	<p>will create an <tt>AllocaInst</tt> instance that represents the allocation of
				775	one integer in the current stack frame, at runtime. Each <tt>Instruction</tt>
				776	subclass is likely to have varying default parameters which change the semantics
				777	of the instruction, so refer to the <a
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	778	href="/doxygen/classllvm_1_1Instruction.html">doxygen documentation for the subclass of
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	779	Instruction</a> that you're interested in instantiating.</p>
				780
				781	<p><i>Naming values</i></p>
				782
				783	<p>It is very useful to name the values of instructions when you're able to, as
				784	this facilitates the debugging of your transformations. If you end up looking
				785	at generated LLVM machine code, you definitely want to have logical names
				786	associated with the results of instructions! By supplying a value for the
				787	<tt>Name</tt> (default) parameter of the <tt>Instruction</tt> constructor, you
				788	associate a logical name with the result of the instruction's execution at
				789	runtime. For example, say that I'm writing a transformation that dynamically
				790	allocates space for an integer on the stack, and that integer is going to be
				791	used as some kind of index by some other code. To accomplish this, I place an
				792	<tt>AllocaInst</tt> at the first point in the first <tt>BasicBlock</tt> of some
				793	<tt>Function</tt>, and I'm intending to use it within the same
				794	<tt>Function</tt>. I might do:</p>
				795
				796	<pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre>
				797
				798	<p>where <tt>indexLoc</tt> is now the logical name of the instruction's
				799	execution value, which is a pointer to an integer on the runtime stack.</p>
				800
				801	<p><i>Inserting instructions</i></p>
				802
				803	<p>There are essentially two ways to insert an <tt>Instruction</tt>
				804	into an existing sequence of instructions that form a <tt>BasicBlock</tt>:</p>
				805
Joel Stanley	9dd1ad6	2002-09-18 03:17:23 +0000	[diff] [blame]	806	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	807	<li>Insertion into an explicit instruction list
				808
				809	<p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> within that
				810	<tt>BasicBlock</tt>, and a newly-created instruction we wish to insert
				811	before <tt>*pi</tt>, we do the following: </p>
				812
Alkis Evlogimenos	9a5dc4f	2004-05-27 00:57:51 +0000	[diff] [blame]	813	<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>
				814
				815	<p>Appending to the end of a <tt>BasicBlock</tt> is so common that
				816	the <tt>Instruction</tt> class and <tt>Instruction</tt>-derived
				817	classes provide constructors which take a pointer to a
				818	<tt>BasicBlock</tt> to be appended to. For example code that
				819	looked like: </p>
				820
				821	<pre> BasicBlock pb = ...;<br> Instruction newInst = new Instruction(...);<br> pb->getInstList().push_back(newInst); // appends newInst to pb<br></pre>
				822
				823	<p>becomes: </p>
				824
				825	<pre> BasicBlock pb = ...;<br> Instruction newInst = new Instruction(..., pb);<br></pre>
				826
				827	<p>which is much cleaner, especially if you are creating
				828	long instruction streams.</p></li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	829
				830	<li>Insertion into an implicit instruction list
				831
				832	<p><tt>Instruction</tt> instances that are already in <tt>BasicBlock</tt>s
				833	are implicitly associated with an existing instruction list: the instruction
				834	list of the enclosing basic block. Thus, we could have accomplished the same
				835	thing as the above code without being given a <tt>BasicBlock</tt> by doing:
				836	</p>
				837
				838	<pre> Instruction pi = ...;<br> Instruction newInst = new Instruction(...);<br> pi->getParent()->getInstList().insert(pi, newInst);<br></pre>
				839
				840	<p>In fact, this sequence of steps occurs so frequently that the
				841	<tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes provide
				842	constructors which take (as a default parameter) a pointer to an
				843	<tt>Instruction</tt> which the newly-created <tt>Instruction</tt> should
				844	precede. That is, <tt>Instruction</tt> constructors are capable of
				845	inserting the newly-created instance into the <tt>BasicBlock</tt> of a
				846	provided instruction, immediately before that instruction. Using an
				847	<tt>Instruction</tt> constructor with a <tt>insertBefore</tt> (default)
				848	parameter, the above code becomes:</p>
				849
				850	<pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre>
				851
				852	<p>which is much cleaner, especially if you're creating a lot of
				853	instructions and adding them to <tt>BasicBlock</tt>s.</p></li>
				854	</ul>
				855
				856	</div>
				857
				858	<!--_______________________________________________________________________-->
				859	<div class="doc_subsubsection">
				860	<a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a>
				861	</div>
				862
				863	<div class="doc_text">
				864
				865	<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]	866	<a href="#BasicBlock"><tt>BasicBlock</tt></a> is very straight-forward. First,
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	867	you must have a pointer to the instruction that you wish to delete. Second, you
				868	need to obtain the pointer to that instruction's basic block. You use the
				869	pointer to the basic block to get its list of instructions and then use the
				870	erase function to remove your instruction. For example:</p>
				871
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	872	<pre> <a href="#Instruction">Instruction</a> *I = .. ;<br> <a
				873	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]	874
				875	</div>
				876
				877	<!--_______________________________________________________________________-->
				878	<div class="doc_subsubsection">
				879	<a name="schanges_replacing">Replacing an <tt>Instruction</tt> with another
				880	<tt>Value</tt></a>
				881	</div>
				882
				883	<div class="doc_text">
				884
				885	<p><i>Replacing individual instructions</i></p>
				886
				887	<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]	888	permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	889	and <tt>ReplaceInstWithInst</tt>.</p>
				890
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	891	<h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	892
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	893	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	894	<li><tt>ReplaceInstWithValue</tt>
				895
				896	<p>This function replaces all uses (within a basic block) of a given
				897	instruction with a value, and then removes the original instruction. The
				898	following example illustrates the replacement of the result of a particular
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	899	<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]	900	pointer to an integer.</p>
				901
				902	<pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,<br> Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre></li>
				903
				904	<li><tt>ReplaceInstWithInst</tt>
				905
				906	<p>This function replaces a particular instruction with another
				907	instruction. The following example illustrates the replacement of one
				908	<tt>AllocaInst</tt> with another.</p>
				909
				910	<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]	911	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	912
				913	<p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p>
				914
				915	<p>You can use <tt>Value::replaceAllUsesWith</tt> and
				916	<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]	917	doxygen documentation for the <a href="/doxygen/structllvm_1_1Value.html">Value Class</a>
				918	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]	919	information.</p>
				920
				921	<!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out:
				922	include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with:
				923	ReplaceInstWithValue, ReplaceInstWithInst -->
				924
				925	</div>
				926
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	927	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	928	<div class="doc_section">
				929	<a name="coreclasses">The Core LLVM Class Hierarchy Reference </a>
				930	</div>
				931	<!-- *********************************************************************** -->
				932
				933	<div class="doc_text">
				934
				935	<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]	936	being inspected or transformed. The core LLVM classes are defined in
				937	header files in the <tt>include/llvm/</tt> directory, and implemented in
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	938	the <tt>lib/VMCore</tt> directory.</p>
				939
				940	</div>
				941
				942	<!-- ======================================================================= -->
				943	<div class="doc_subsection">
				944	<a name="Value">The <tt>Value</tt> class</a>
				945	</div>
				946
				947	<div>
				948
				949	<p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>
				950	<br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	951	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]	952
				953	<p>The <tt>Value</tt> class is the most important class in the LLVM Source
				954	base. It represents a typed value that may be used (among other things) as an
				955	operand to an instruction. There are many different types of <tt>Value</tt>s,
				956	such as <a href="#Constant"><tt>Constant</tt></a>s,<a
				957	href="#Argument"><tt>Argument</tt></a>s. Even <a
				958	href="#Instruction"><tt>Instruction</tt></a>s and <a
				959	href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p>
				960
				961	<p>A particular <tt>Value</tt> may be used many times in the LLVM representation
				962	for a program. For example, an incoming argument to a function (represented
				963	with an instance of the <a href="#Argument">Argument</a> class) is "used" by
				964	every instruction in the function that references the argument. To keep track
				965	of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
				966	href="#User"><tt>User</tt></a>s that is using it (the <a
				967	href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
				968	graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
				969	def-use information in the program, and is accessible through the <tt>use_</tt>*
				970	methods, shown below.</p>
				971
				972	<p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed,
				973	and this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
				974	method. In addition, all LLVM values can be named. The "name" of the
				975	<tt>Value</tt> is a symbolic string printed in the LLVM code:</p>
				976
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	977	<pre> %<b>foo</b> = add int 1, 2<br></pre>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	978
				979	<p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>
				980	that the name of any value may be missing (an empty string), so names should
				981	<b>ONLY</b> be used for debugging (making the source code easier to read,
				982	debugging printouts), they should not be used to keep track of values or map
				983	between them. For this purpose, use a <tt>std::map</tt> of pointers to the
				984	<tt>Value</tt> itself instead.</p>
				985
				986	<p>One important aspect of LLVM is that there is no distinction between an SSA
				987	variable and the operation that produces it. Because of this, any reference to
				988	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]	989	argument, for example) is represented as a direct pointer to the instance of
				990	the class that
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	991	represents this value. Although this may take some getting used to, it
				992	simplifies the representation and makes it easier to manipulate.</p>
				993
				994	</div>
				995
				996	<!-- _______________________________________________________________________ -->
				997	<div class="doc_subsubsection">
				998	<a name="m_Value">Important Public Members of the <tt>Value</tt> class</a>
				999	</div>
				1000
				1001	<div class="doc_text">
				1002
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1003	<ul>
				1004	<li><tt>Value::use_iterator</tt> - Typedef for iterator over the
				1005	use-list<br>
				1006	<tt>Value::use_const_iterator</tt> - Typedef for const_iterator over
				1007	the use-list<br>
				1008	<tt>unsigned use_size()</tt> - Returns the number of users of the
				1009	value.<br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1010	<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]	1011	<tt>use_iterator use_begin()</tt> - Get an iterator to the start of
				1012	the use-list.<br>
				1013	<tt>use_iterator use_end()</tt> - Get an iterator to the end of the
				1014	use-list.<br>
				1015	<tt><a href="#User">User</a> *use_back()</tt> - Returns the last
				1016	element in the list.
				1017	<p> These methods are the interface to access the def-use
				1018	information in LLVM. As with all other iterators in LLVM, the naming
				1019	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]	1020	</li>
				1021	<li><tt><a href="#Type">Type</a> *getType() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1022	<p>This method returns the Type of the Value.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1023	</li>
				1024	<li><tt>bool hasName() const</tt><br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1025	<tt>std::string getName() const</tt><br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1026	<tt>void setName(const std::string &Name)</tt>
				1027	<p> This family of methods is used to access and assign a name to a <tt>Value</tt>,
				1028	be aware of the <a href="#nameWarning">precaution above</a>.</p>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1029	</li>
				1030	<li><tt>void replaceAllUsesWith(Value *V)</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1031
				1032	<p>This method traverses the use list of a <tt>Value</tt> changing all <a
				1033	href="#User"><tt>User</tt>s</a> of the current value to refer to
				1034	"<tt>V</tt>" instead. For example, if you detect that an instruction always
				1035	produces a constant value (for example through constant folding), you can
				1036	replace all uses of the instruction with the constant like this:</p>
				1037
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1038	<pre> Inst->replaceAllUsesWith(ConstVal);<br></pre>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1039	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1040
				1041	</div>
				1042
				1043	<!-- ======================================================================= -->
				1044	<div class="doc_subsection">
				1045	<a name="User">The <tt>User</tt> class</a>
				1046	</div>
				1047
				1048	<div class="doc_text">
				1049
				1050	<p>
				1051	<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]	1052	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]	1053	Superclass: <a href="#Value"><tt>Value</tt></a></p>
				1054
				1055	<p>The <tt>User</tt> class is the common base class of all LLVM nodes that may
				1056	refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
				1057	that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
				1058	referring to. The <tt>User</tt> class itself is a subclass of
				1059	<tt>Value</tt>.</p>
				1060
				1061	<p>The operands of a <tt>User</tt> point directly to the LLVM <a
				1062	href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
				1063	Single Assignment (SSA) form, there can only be one definition referred to,
				1064	allowing this direct connection. This connection provides the use-def
				1065	information in LLVM.</p>
				1066
				1067	</div>
				1068
				1069	<!-- _______________________________________________________________________ -->
				1070	<div class="doc_subsubsection">
				1071	<a name="m_User">Important Public Members of the <tt>User</tt> class</a>
				1072	</div>
				1073
				1074	<div class="doc_text">
				1075
				1076	<p>The <tt>User</tt> class exposes the operand list in two ways: through
				1077	an index access interface and through an iterator based interface.</p>
				1078
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1079	<ul>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1080	<li><tt>Value *getOperand(unsigned i)</tt><br>
				1081	<tt>unsigned getNumOperands()</tt>
				1082	<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]	1083	convenient form for direct access.</p></li>
				1084
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1085	<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand
				1086	list<br>
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	1087	<tt>op_iterator op_begin()</tt> - Get an iterator to the start of
				1088	the operand list.<br>
				1089	<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]	1090	operand list.
				1091	<p> Together, these methods make up the iterator based interface to
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1092	the operands of a <tt>User</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1093	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1094
				1095	</div>
				1096
				1097	<!-- ======================================================================= -->
				1098	<div class="doc_subsection">
				1099	<a name="Instruction">The <tt>Instruction</tt> class</a>
				1100	</div>
				1101
				1102	<div class="doc_text">
				1103
				1104	<p><tt>#include "</tt><tt><a
				1105	href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt><br>
Misha Brukman	31ca1de	2004-06-03 23:35:54 +0000	[diff] [blame]	1106	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]	1107	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				1108	href="#Value"><tt>Value</tt></a></p>
				1109
				1110	<p>The <tt>Instruction</tt> class is the common base class for all LLVM
				1111	instructions. It provides only a few methods, but is a very commonly used
				1112	class. The primary data tracked by the <tt>Instruction</tt> class itself is the
				1113	opcode (instruction type) and the parent <a
				1114	href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
				1115	into. To represent a specific type of instruction, one of many subclasses of
				1116	<tt>Instruction</tt> are used.</p>
				1117
				1118	<p> Because the <tt>Instruction</tt> class subclasses the <a
				1119	href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
				1120	way as for other <a href="#User"><tt>User</tt></a>s (with the
				1121	<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
				1122	<tt>op_begin()</tt>/<tt>op_end()</tt> methods).</p> <p> An important file for
				1123	the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> file. This
				1124	file contains some meta-data about the various different types of instructions
				1125	in LLVM. It describes the enum values that are used as opcodes (for example
				1126	<tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), as well as the
				1127	concrete sub-classes of <tt>Instruction</tt> that implement the instruction (for
				1128	example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a
				1129	href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, the use of macros in
				1130	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]	1131	<a href="/doxygen/classllvm_1_1Instruction.html">doxygen output</a>.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1132
				1133	</div>
				1134
				1135	<!-- _______________________________________________________________________ -->
				1136	<div class="doc_subsubsection">
				1137	<a name="m_Instruction">Important Public Members of the <tt>Instruction</tt>
				1138	class</a>
				1139	</div>
				1140
				1141	<div class="doc_text">
				1142
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1143	<ul>
				1144	<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1145	<p>Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that
				1146	this <tt>Instruction</tt> is embedded into.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1147	<li><tt>bool mayWriteToMemory()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1148	<p>Returns true if the instruction writes to memory, i.e. it is a
				1149	<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]	1150	<li><tt>unsigned getOpcode()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1151	<p>Returns the opcode for the <tt>Instruction</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1152	<li><tt><a href="#Instruction">Instruction</a> *clone() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1153	<p>Returns another instance of the specified instruction, identical
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1154	in all ways to the original except that the instruction has no parent
				1155	(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]	1156	and it has no name</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1157	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1158
				1159	</div>
				1160
				1161	<!-- ======================================================================= -->
				1162	<div class="doc_subsection">
				1163	<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
				1164	</div>
				1165
				1166	<div class="doc_text">
				1167
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1168	<p><tt>#include "<a
				1169	href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br>
				1170	doxygen info: <a href="/doxygen/structllvm_1_1BasicBlock.html">BasicBlock
				1171	Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1172	Superclass: <a href="#Value"><tt>Value</tt></a></p>
				1173
				1174	<p>This class represents a single entry multiple exit section of the code,
				1175	commonly known as a basic block by the compiler community. The
				1176	<tt>BasicBlock</tt> class maintains a list of <a
				1177	href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block.
				1178	Matching the language definition, the last element of this list of instructions
				1179	is always a terminator instruction (a subclass of the <a
				1180	href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p>
				1181
				1182	<p>In addition to tracking the list of instructions that make up the block, the
				1183	<tt>BasicBlock</tt> class also keeps track of the <a
				1184	href="#Function"><tt>Function</tt></a> that it is embedded into.</p>
				1185
				1186	<p>Note that <tt>BasicBlock</tt>s themselves are <a
				1187	href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
				1188	like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
				1189	<tt>label</tt>.</p>
				1190
				1191	</div>
				1192
				1193	<!-- _______________________________________________________________________ -->
				1194	<div class="doc_subsubsection">
				1195	<a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt>
				1196	class</a>
				1197	</div>
				1198
				1199	<div class="doc_text">
				1200
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1201	<ul>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1202
				1203	<li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1204	href="#Function">Function</a> *Parent = 0)</tt>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1205
				1206	<p>The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
				1207	insertion into a function. The constructor optionally takes a name for the new
				1208	block, and a <a href="#Function"><tt>Function</tt></a> to insert it into. If
				1209	the <tt>Parent</tt> parameter is specified, the new <tt>BasicBlock</tt> is
				1210	automatically inserted at the end of the specified <a
				1211	href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
				1212	manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p></li>
				1213
				1214	<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
				1215	<tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
				1216	<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1217	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	b0e7e45	2004-10-29 04:33:19 +0000	[diff] [blame]	1218	STL-style functions for accessing the instruction list.
				1219
				1220	<p>These methods and typedefs are forwarding functions that have the same
				1221	semantics as the standard library methods of the same names. These methods
				1222	expose the underlying instruction list of a basic block in a way that is easy to
				1223	manipulate. To get the full complement of container operations (including
				1224	operations to update the list), you must use the <tt>getInstList()</tt>
				1225	method.</p></li>
				1226
				1227	<li><tt>BasicBlock::InstListType &getInstList()</tt>
				1228
				1229	<p>This method is used to get access to the underlying container that actually
				1230	holds the Instructions. This method must be used when there isn't a forwarding
				1231	function in the <tt>BasicBlock</tt> class for the operation that you would like
				1232	to perform. Because there are no forwarding functions for "updating"
				1233	operations, you need to use this if you want to update the contents of a
				1234	<tt>BasicBlock</tt>.</p></li>
				1235
				1236	<li><tt><a href="#Function">Function</a> *getParent()</tt>
				1237
				1238	<p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
				1239	embedded into, or a null pointer if it is homeless.</p></li>
				1240
				1241	<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt>
				1242
				1243	<p> Returns a pointer to the terminator instruction that appears at the end of
				1244	the <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
				1245	instruction in the block is not a terminator, then a null pointer is
				1246	returned.</p></li>
				1247
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1248	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1249
				1250	</div>
				1251
				1252	<!-- ======================================================================= -->
				1253	<div class="doc_subsection">
				1254	<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
				1255	</div>
				1256
				1257	<div class="doc_text">
				1258
				1259	<p><tt>#include "<a
				1260	href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br>
Misha Brukman	384047f	2004-06-03 23:29:12 +0000	[diff] [blame]	1261	doxygen info: <a href="/doxygen/classllvm_1_1GlobalValue.html">GlobalValue
				1262	Class</a><br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1263	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				1264	href="#Value"><tt>Value</tt></a></p>
				1265
				1266	<p>Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
				1267	href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
				1268	visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
				1269	Because they are visible at global scope, they are also subject to linking with
				1270	other globals defined in different translation units. To control the linking
				1271	process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
				1272	<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]	1273	defined by the <tt>LinkageTypes</tt> enumeration.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1274
				1275	<p>If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
				1276	<tt>static</tt> in C), it is not visible to code outside the current translation
				1277	unit, and does not participate in linking. If it has external linkage, it is
				1278	visible to external code, and does participate in linking. In addition to
				1279	linkage information, <tt>GlobalValue</tt>s keep track of which <a
				1280	href="#Module"><tt>Module</tt></a> they are currently part of.</p>
				1281
				1282	<p>Because <tt>GlobalValue</tt>s are memory objects, they are always referred to
				1283	by their <b>address</b>. As such, the <a href="#Type"><tt>Type</tt></a> of a
				1284	global is always a pointer to its contents. It is important to remember this
				1285	when using the <tt>GetElementPtrInst</tt> instruction because this pointer must
				1286	be dereferenced first. For example, if you have a <tt>GlobalVariable</tt> (a
				1287	subclass of <tt>GlobalValue)</tt> that is an array of 24 ints, type <tt>[24 x
				1288	int]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although
				1289	the address of the first element of this array and the value of the
				1290	<tt>GlobalVariable</tt> are the same, they have different types. The
				1291	<tt>GlobalVariable</tt>'s type is <tt>[24 x int]</tt>. The first element's type
				1292	is <tt>int.</tt> Because of this, accessing a global value requires you to
				1293	dereference the pointer with <tt>GetElementPtrInst</tt> first, then its elements
				1294	can be accessed. This is explained in the <a href="LangRef.html#globalvars">LLVM
				1295	Language Reference Manual</a>.</p>
				1296
				1297	</div>
				1298
				1299	<!-- _______________________________________________________________________ -->
				1300	<div class="doc_subsubsection">
				1301	<a name="m_GlobalValue">Important Public Members of the <tt>GlobalValue</tt>
				1302	class</a>
				1303	</div>
				1304
				1305	<div class="doc_text">
				1306
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1307	<ul>
				1308	<li><tt>bool hasInternalLinkage() const</tt><br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1309	<tt>bool hasExternalLinkage() const</tt><br>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1310	<tt>void setInternalLinkage(bool HasInternalLinkage)</tt>
				1311	<p> These methods manipulate the linkage characteristics of the <tt>GlobalValue</tt>.</p>
				1312	<p> </p>
				1313	</li>
				1314	<li><tt><a href="#Module">Module</a> *getParent()</tt>
				1315	<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]	1316	GlobalValue is currently embedded into.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1317	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1318
				1319	</div>
				1320
				1321	<!-- ======================================================================= -->
				1322	<div class="doc_subsection">
				1323	<a name="Function">The <tt>Function</tt> class</a>
				1324	</div>
				1325
				1326	<div class="doc_text">
				1327
				1328	<p><tt>#include "<a
				1329	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]	1330	info: <a href="/doxygen/classllvm_1_1Function.html">Function Class</a><br>
				1331	Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1332	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
				1333
				1334	<p>The <tt>Function</tt> class represents a single procedure in LLVM. It is
				1335	actually one of the more complex classes in the LLVM heirarchy because it must
				1336	keep track of a large amount of data. The <tt>Function</tt> class keeps track
				1337	of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
				1338	href="#Argument"><tt>Argument</tt></a>s, and a <a
				1339	href="#SymbolTable"><tt>SymbolTable</tt></a>.</p>
				1340
				1341	<p>The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most
				1342	commonly used part of <tt>Function</tt> objects. The list imposes an implicit
				1343	ordering of the blocks in the function, which indicate how the code will be
				1344	layed out by the backend. Additionally, the first <a
				1345	href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
				1346	<tt>Function</tt>. It is not legal in LLVM to explicitly branch to this initial
				1347	block. There are no implicit exit nodes, and in fact there may be multiple exit
				1348	nodes from a single <tt>Function</tt>. If the <a
				1349	href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
				1350	the <tt>Function</tt> is actually a function declaration: the actual body of the
				1351	function hasn't been linked in yet.</p>
				1352
				1353	<p>In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
				1354	<tt>Function</tt> class also keeps track of the list of formal <a
				1355	href="#Argument"><tt>Argument</tt></a>s that the function receives. This
				1356	container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
				1357	nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
				1358	the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.</p>
				1359
				1360	<p>The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used
				1361	LLVM feature that is only used when you have to look up a value by name. Aside
				1362	from that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used
				1363	internally to make sure that there are not conflicts between the names of <a
				1364	href="#Instruction"><tt>Instruction</tt></a>s, <a
				1365	href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
				1366	href="#Argument"><tt>Argument</tt></a>s in the function body.</p>
				1367
Reid Spencer	8b2da7a	2004-07-18 13:10:31 +0000	[diff] [blame]	1368	<p>Note that <tt>Function</tt> is a <a href="#GlobalValue">GlobalValue</a>
				1369	and therefore also a <a href="#Constant">Constant</a>. The value of the function
				1370	is its address (after linking) which is guaranteed to be constant.</p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1371	</div>
				1372
				1373	<!-- _______________________________________________________________________ -->
				1374	<div class="doc_subsubsection">
				1375	<a name="m_Function">Important Public Members of the <tt>Function</tt>
				1376	class</a>
				1377	</div>
				1378
				1379	<div class="doc_text">
				1380
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1381	<ul>
				1382	<li><tt>Function(const </tt><tt><a href="#FunctionType">FunctionType</a>
Chris Lattner	ac479e5	2004-08-04 05:10:48 +0000	[diff] [blame]	1383	Ty, LinkageTypes Linkage, const std::string &N = "", Module Parent = 0)</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1384
				1385	<p>Constructor used when you need to create new <tt>Function</tt>s to add
				1386	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]	1387	create and what type of linkage the function should have. The <a
				1388	href="#FunctionType"><tt>FunctionType</tt></a> argument
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1389	specifies the formal arguments and return value for the function. The same
				1390	<a href="#FunctionTypel"><tt>FunctionType</tt></a> value can be used to
				1391	create multiple functions. The <tt>Parent</tt> argument specifies the Module
				1392	in which the function is defined. If this argument is provided, the function
				1393	will automatically be inserted into that module's list of
				1394	functions.</p></li>
				1395
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1396	<li><tt>bool isExternal()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1397
				1398	<p>Return whether or not the <tt>Function</tt> has a body defined. If the
				1399	function is "external", it does not have a body, and thus must be resolved
				1400	by linking with a function defined in a different translation unit.</p></li>
				1401
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1402	<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1403	<tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1404
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1405	<tt>begin()</tt>, <tt>end()</tt>
				1406	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1407
				1408	<p>These are forwarding methods that make it easy to access the contents of
				1409	a <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
				1410	list.</p></li>
				1411
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1412	<li><tt>Function::BasicBlockListType &getBasicBlockList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1413
				1414	<p>Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This
				1415	is necessary to use when you need to update the list or perform a complex
				1416	action that doesn't have a forwarding method.</p></li>
				1417
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1418	<li><tt>Function::arg_iterator</tt> - Typedef for the argument list
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1419	iterator<br>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1420	<tt>Function::const_arg_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1421
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1422	<tt>arg_begin()</tt>, <tt>arg_end()</tt>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1423	<tt>arg_size()</tt>, <tt>arg_empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1424
				1425	<p>These are forwarding methods that make it easy to access the contents of
				1426	a <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a>
				1427	list.</p></li>
				1428
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1429	<li><tt>Function::ArgumentListType &getArgumentList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1430
				1431	<p>Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
				1432	necessary to use when you need to update the list or perform a complex
				1433	action that doesn't have a forwarding method.</p></li>
				1434
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1435	<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryBlock()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1436
				1437	<p>Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
				1438	function. Because the entry block for the function is always the first
				1439	block, this returns the first block of the <tt>Function</tt>.</p></li>
				1440
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1441	<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
				1442	<tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1443
				1444	<p>This traverses the <a href="#Type"><tt>Type</tt></a> of the
				1445	<tt>Function</tt> and returns the return type of the function, or the <a
				1446	href="#FunctionType"><tt>FunctionType</tt></a> of the actual
				1447	function.</p></li>
				1448
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1449	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1450
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1451	<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]	1452	for this <tt>Function</tt>.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1453	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1454
				1455	</div>
				1456
				1457	<!-- ======================================================================= -->
				1458	<div class="doc_subsection">
				1459	<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
				1460	</div>
				1461
				1462	<div class="doc_text">
				1463
				1464	<p><tt>#include "<a
				1465	href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt>
				1466	<br>
Tanya Lattner	a3da777	2004-06-22 08:02:25 +0000	[diff] [blame]	1467	doxygen info: <a href="/doxygen/classllvm_1_1GlobalVariable.html">GlobalVariable
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1468	Class</a><br> Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
				1469	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
				1470
				1471	<p>Global variables are represented with the (suprise suprise)
				1472	<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are also
				1473	subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are
				1474	always referenced by their address (global values must live in memory, so their
				1475	"name" refers to their address). See <a
				1476	href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global variables
				1477	may have an initial value (which must be a <a
				1478	href="#Constant"><tt>Constant</tt></a>), and if they have an initializer, they
				1479	may be marked as "constant" themselves (indicating that their contents never
				1480	change at runtime).</p>
				1481
				1482	</div>
				1483
				1484	<!-- _______________________________________________________________________ -->
				1485	<div class="doc_subsubsection">
				1486	<a name="m_GlobalVariable">Important Public Members of the
				1487	<tt>GlobalVariable</tt> class</a>
				1488	</div>
				1489
				1490	<div class="doc_text">
				1491
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1492	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1493	<li><tt>GlobalVariable(const </tt><tt><a href="#Type">Type</a> *Ty, bool
				1494	isConstant, LinkageTypes& Linkage, <a href="#Constant">Constant</a>
				1495	Initializer = 0, const std::string &Name = "", Module Parent = 0)</tt>
				1496
				1497	<p>Create a new global variable of the specified type. If
				1498	<tt>isConstant</tt> is true then the global variable will be marked as
				1499	unchanging for the program. The Linkage parameter specifies the type of
				1500	linkage (internal, external, weak, linkonce, appending) for the variable. If
				1501	the linkage is InternalLinkage, WeakLinkage, or LinkOnceLinkage,  then
				1502	the resultant global variable will have internal linkage. AppendingLinkage
				1503	concatenates together all instances (in different translation units) of the
				1504	variable into a single variable but is only applicable to arrays.  See
				1505	the <a href="LangRef.html#modulestructure">LLVM Language Reference</a> for
				1506	further details on linkage types. Optionally an initializer, a name, and the
				1507	module to put the variable into may be specified for the global variable as
				1508	well.</p></li>
				1509
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1510	<li><tt>bool isConstant() const</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1511
				1512	<p>Returns true if this is a global variable that is known not to
				1513	be modified at runtime.</p></li>
				1514
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1515	<li><tt>bool hasInitializer()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1516
				1517	<p>Returns true if this <tt>GlobalVariable</tt> has an intializer.</p></li>
				1518
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1519	<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1520
				1521	<p>Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal
				1522	to call this method if there is no initializer.</p></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1523	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1524
				1525	</div>
				1526
				1527	<!-- ======================================================================= -->
				1528	<div class="doc_subsection">
				1529	<a name="Module">The <tt>Module</tt> class</a>
				1530	</div>
				1531
				1532	<div class="doc_text">
				1533
				1534	<p><tt>#include "<a
				1535	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]	1536	<a href="/doxygen/classllvm_1_1Module.html">Module Class</a></p>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1537
				1538	<p>The <tt>Module</tt> class represents the top level structure present in LLVM
				1539	programs. An LLVM module is effectively either a translation unit of the
				1540	original program or a combination of several translation units merged by the
				1541	linker. The <tt>Module</tt> class keeps track of a list of <a
				1542	href="#Function"><tt>Function</tt></a>s, a list of <a
				1543	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
				1544	href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
				1545	helpful member functions that try to make common operations easy.</p>
				1546
				1547	</div>
				1548
				1549	<!-- _______________________________________________________________________ -->
				1550	<div class="doc_subsubsection">
				1551	<a name="m_Module">Important Public Members of the <tt>Module</tt> class</a>
				1552	</div>
				1553
				1554	<div class="doc_text">
				1555
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1556	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1557	<li><tt>Module::Module(std::string name = "")</tt></li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1558	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1559
				1560	<p>Constructing a <a href="#Module">Module</a> is easy. You can optionally
				1561	provide a name for it (probably based on the name of the translation unit).</p>
				1562
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1563	<ul>
				1564	<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	1565	<tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1566
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1567	<tt>begin()</tt>, <tt>end()</tt>
				1568	<tt>size()</tt>, <tt>empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1569
				1570	<p>These are forwarding methods that make it easy to access the contents of
				1571	a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
				1572	list.</p></li>
				1573
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1574	<li><tt>Module::FunctionListType &getFunctionList()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1575
				1576	<p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
				1577	necessary to use when you need to update the list or perform a complex
				1578	action that doesn't have a forwarding method.</p>
				1579
				1580	<p><!-- Global Variable --></p></li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1581	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1582
				1583	<hr>
				1584
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1585	<ul>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1586	<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]	1587
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1588	<tt>Module::const_global_iterator</tt> - Typedef for const_iterator.<br>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1589
Chris Lattner	77d6924	2005-03-15 05:19:20 +0000	[diff] [blame]	1590	<tt>global_begin()</tt>, <tt>global_end()</tt>
Chris Lattner	89cc265	2005-03-15 04:48:32 +0000	[diff] [blame]	1591	<tt>global_size()</tt>, <tt>global_empty()</tt>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1592
				1593	<p> These are forwarding methods that make it easy to access the contents of
				1594	a <tt>Module</tt> object's <a
				1595	href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li>
				1596
				1597	<li><tt>Module::GlobalListType &getGlobalList()</tt>
				1598
				1599	<p>Returns the list of <a
				1600	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. This is necessary to
				1601	use when you need to update the list or perform a complex action that
				1602	doesn't have a forwarding method.</p>
				1603
				1604	<p><!-- Symbol table stuff --> </p></li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1605	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1606
				1607	<hr>
				1608
				1609	<ul>
				1610	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
				1611
				1612	<p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
				1613	for this <tt>Module</tt>.</p>
				1614
				1615	<p><!-- Convenience methods --></p></li>
				1616	</ul>
				1617
				1618	<hr>
				1619
				1620	<ul>
				1621	<li><tt><a href="#Function">Function</a> *getFunction(const std::string
				1622	&Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt>
				1623
				1624	<p>Look up the specified function in the <tt>Module</tt> <a
				1625	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
				1626	<tt>null</tt>.</p></li>
				1627
				1628	<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const
				1629	std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt>
				1630
				1631	<p>Look up the specified function in the <tt>Module</tt> <a
				1632	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
				1633	external declaration for the function and return it.</p></li>
				1634
				1635	<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt>
				1636
				1637	<p>If there is at least one entry in the <a
				1638	href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
				1639	href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
				1640	string.</p></li>
				1641
				1642	<li><tt>bool addTypeName(const std::string &Name, const <a
				1643	href="#Type">Type</a> *Ty)</tt>
				1644
				1645	<p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
				1646	mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this
				1647	name, true is returned and the <a
				1648	href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li>
				1649	</ul>
				1650
				1651	</div>
				1652
				1653	<!-- ======================================================================= -->
				1654	<div class="doc_subsection">
				1655	<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
				1656	</div>
				1657
				1658	<div class="doc_text">
				1659
				1660	<p>Constant represents a base class for different types of constants. It
				1661	is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
				1662	ConstantArray etc for representing the various types of Constants.</p>
				1663
				1664	</div>
				1665
				1666	<!-- _______________________________________________________________________ -->
				1667	<div class="doc_subsubsection">
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1668	<a name="m_Constant">Important Public Methods</a>
				1669	</div>
				1670	<div class="doc_text">
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1671	</div>
				1672
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1673	<!-- _______________________________________________________________________ -->
				1674	<div class="doc_subsubsection">Important Subclasses of Constant </div>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1675	<div class="doc_text">
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1676	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1677	<li>ConstantSInt : This subclass of Constant represents a signed integer
				1678	constant.
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1679	<ul>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1680	<li><tt>int64_t getValue() const</tt>: Returns the underlying value of
				1681	this constant. </li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1682	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1683	</li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1684	<li>ConstantUInt : This class represents an unsigned integer.
				1685	<ul>
				1686	<li><tt>uint64_t getValue() const</tt>: Returns the underlying value of
				1687	this constant. </li>
				1688	</ul>
				1689	</li>
				1690	<li>ConstantFP : This class represents a floating point constant.
				1691	<ul>
				1692	<li><tt>double getValue() const</tt>: Returns the underlying value of
				1693	this constant. </li>
				1694	</ul>
				1695	</li>
				1696	<li>ConstantBool : This represents a boolean constant.
				1697	<ul>
				1698	<li><tt>bool getValue() const</tt>: Returns the underlying value of this
				1699	constant. </li>
				1700	</ul>
				1701	</li>
				1702	<li>ConstantArray : This represents a constant array.
				1703	<ul>
				1704	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	1705	a vector of component constants that makeup this array. </li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1706	</ul>
				1707	</li>
				1708	<li>ConstantStruct : This represents a constant struct.
				1709	<ul>
				1710	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	1711	a vector of component constants that makeup this array. </li>
Reid Spencer	fe8f4ff	2004-11-01 09:02:53 +0000	[diff] [blame]	1712	</ul>
				1713	</li>
				1714	<li>GlobalValue : This represents either a global variable or a function. In
				1715	either case, the value is a constant fixed address (after linking).
				1716	</li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1717	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1718	</div>
				1719
				1720	<!-- ======================================================================= -->
				1721	<div class="doc_subsection">
				1722	<a name="Type">The <tt>Type</tt> class and Derived Types</a>
				1723	</div>
				1724
				1725	<div class="doc_text">
				1726
				1727	<p>Type as noted earlier is also a subclass of a Value class. Any primitive
				1728	type (like int, short etc) in LLVM is an instance of Type Class. All other
				1729	types are instances of subclasses of type like FunctionType, ArrayType
				1730	etc. DerivedType is the interface for all such dervied types including
				1731	FunctionType, ArrayType, PointerType, StructType. Types can have names. They can
				1732	be recursive (StructType). There exists exactly one instance of any type
				1733	structure at a time. This allows using pointer equality of Type *s for comparing
				1734	types.</p>
				1735
				1736	</div>
				1737
				1738	<!-- _______________________________________________________________________ -->
				1739	<div class="doc_subsubsection">
				1740	<a name="m_Value">Important Public Methods</a>
				1741	</div>
				1742
				1743	<div class="doc_text">
				1744
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1745	<ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1746
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1747	<li><tt>bool isSigned() const</tt>: Returns whether an integral numeric type
				1748	is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is
				1749	not true for Float and Double. </li>
				1750
				1751	<li><tt>bool isUnsigned() const</tt>: Returns whether a numeric type is
				1752	unsigned. This is not quite the complement of isSigned... nonnumeric types
				1753	return false as they do with isSigned. This returns true for UByteTy,
				1754	UShortTy, UIntTy, and ULongTy. </li>
				1755
Chris Lattner	4573f1b	2004-07-08 17:49:37 +0000	[diff] [blame]	1756	<li><tt>bool isInteger() const</tt>: Equivalent to isSigned() \|\| isUnsigned().</li>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1757
				1758	<li><tt>bool isIntegral() const</tt>: Returns true if this is an integral
				1759	type, which is either Bool type or one of the Integer types.</li>
				1760
				1761	<li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two
				1762	floating point types.</li>
				1763
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1764	<li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if
				1765	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]	1766	example, uint to int or one pointer type to another.</li>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1767	</ul>
				1768	</div>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1769
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1770	<!-- _______________________________________________________________________ -->
				1771	<div class="doc_subsubsection">
				1772	<a name="m_Value">Important Derived Types</a>
				1773	</div>
				1774	<div class="doc_text">
				1775	<ul>
				1776	<li>SequentialType : This is subclassed by ArrayType and PointerType
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1777	<ul>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1778	<li><tt>const Type * getElementType() const</tt>: Returns the type of each
				1779	of the elements in the sequential type. </li>
				1780	</ul>
				1781	</li>
				1782	<li>ArrayType : This is a subclass of SequentialType and defines interface for
				1783	array types.
				1784	<ul>
				1785	<li><tt>unsigned getNumElements() const</tt>: Returns the number of
				1786	elements in the array. </li>
				1787	</ul>
				1788	</li>
				1789	<li>PointerType : Subclass of SequentialType for pointer types. </li>
				1790	<li>StructType : subclass of DerivedTypes for struct types </li>
				1791	<li>FunctionType : subclass of DerivedTypes for function types.
				1792	<ul>
				1793	<li><tt>bool isVarArg() const</tt>: Returns true if its a vararg
				1794	function</li>
				1795	<li><tt> const Type * getReturnType() const</tt>: Returns the
				1796	return type of the function.</li>
				1797	<li><tt>const Type * getParamType (unsigned i)</tt>: Returns
				1798	the type of the ith parameter.</li>
				1799	<li><tt> const unsigned getNumParams() const</tt>: Returns the
				1800	number of formal parameters.</li>
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	1801	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1802	</li>
Chris Lattner	c75ff9a	2002-10-01 23:17:09 +0000	[diff] [blame]	1803	</ul>
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1804	</div>
				1805
				1806	<!-- ======================================================================= -->
				1807	<div class="doc_subsection">
				1808	<a name="Argument">The <tt>Argument</tt> class</a>
				1809	</div>
				1810
				1811	<div class="doc_text">
				1812
				1813	<p>This subclass of Value defines the interface for incoming formal
Chris Lattner	5836082	2005-01-17 00:12:04 +0000	[diff] [blame]	1814	arguments to a function. A Function maintains a list of its formal
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	1815	arguments. An argument has a pointer to the parent Function.</p>
				1816
				1817	</div>
				1818
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1819	<!-- ======================================================================= -->
				1820	<div class="doc_subsection">
				1821	<a name="SymbolTable">The <tt>SymbolTable</tt> class</a>
				1822	</div>
				1823	<div class="doc_text">
				1824	<p>This class provides a symbol table that the
				1825	<a href="#Function"><tt>Function</tt></a> and <a href="#Module">
				1826	<tt>Module</tt></a> classes use for naming definitions. The symbol table can
				1827	provide a name for any <a href="#Value"><tt>Value</tt></a> or
				1828	<a href="#Type"><tt>Type</tt></a>. <tt>SymbolTable</tt> is an abstract data
				1829	type. It hides the data it contains and provides access to it through a
				1830	controlled interface.</p>
				1831
				1832	<p>To use the <tt>SymbolTable</tt> well, you need to understand the
				1833	structure of the information it holds. The class contains two
				1834	<tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of
				1835	<tt>Type</tt> to maps of name (<tt>std::string</tt>) to <tt>Value</tt>.
				1836	The second, <tt>tmap</tt>, is a map of names to <tt>Type*</tt>. Thus, Values
				1837	are stored in two-dimensions and accessed by <tt>Type</tt> and name. Types,
				1838	however, are stored in a single dimension and accessed only by name.</p>
				1839
				1840	<p>The interface of this class provides three basic types of operations:
				1841	<ol>
				1842	<li><em>Accessors</em>. Accessors provide read-only access to information
				1843	such as finding a value for a name with the
				1844	<a href="#SymbolTable_lookup">lookup</a> method.</li>
				1845	<li><em>Mutators</em>. Mutators allow the user to add information to the
				1846	<tt>SymbolTable</tt> with methods like
				1847	<a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>
				1848	<li><em>Iterators</em>. Iterators allow the user to traverse the content
				1849	of the symbol table in well defined ways, such as the method
				1850	<a href="#SymbolTable_type_begin"><tt>type_begin</tt></a>.</li>
				1851	</ol>
				1852
				1853	<h3>Accessors</h3>
				1854	<dl>
				1855	<dt><tt>Value* lookup(const Type* Ty, const std::string& name) const</tt>:
				1856	</dt>
				1857	<dd>The <tt>lookup</tt> method searches the type plane given by the
				1858	<tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.
				1859	If a suitable <tt>Value</tt> is not found, null is returned.</dd>
				1860
				1861	<dt><tt>Type* lookupType( const std::string& name) const</tt>:</dt>
				1862	<dd>The <tt>lookupType</tt> method searches through the types for a
				1863	<tt>Type</tt> with the provided <tt>name</tt>. If a suitable <tt>Type</tt>
				1864	is not found, null is returned.</dd>
				1865
				1866	<dt><tt>bool hasTypes() const</tt>:</dt>
				1867	<dd>This function returns true if an entry has been made into the type
				1868	map.</dd>
				1869
				1870	<dt><tt>bool isEmpty() const</tt>:</dt>
				1871	<dd>This function returns true if both the value and types maps are
				1872	empty</dd>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1873	</dl>
				1874
				1875	<h3>Mutators</h3>
				1876	<dl>
				1877	<dt><tt>void insert(Value *Val)</tt>:</dt>
				1878	<dd>This method adds the provided value to the symbol table. The Value must
				1879	have both a name and a type which are extracted and used to place the value
				1880	in the correct type plane under the value's name.</dd>
				1881
				1882	<dt><tt>void insert(const std::string& Name, Value *Val)</tt>:</dt>
				1883	<dd> Inserts a constant or type into the symbol table with the specified
				1884	name. There can be a many to one mapping between names and constants
				1885	or types.</dd>
				1886
				1887	<dt><tt>void insert(const std::string& Name, Type *Typ)</tt>:</dt>
				1888	<dd> Inserts a type into the symbol table with the specified name. There
				1889	can be a many-to-one mapping between names and types. This method
				1890	allows a type with an existing entry in the symbol table to get
				1891	a new name.</dd>
				1892
				1893	<dt><tt>void remove(Value* Val)</tt>:</dt>
				1894	<dd> This method removes a named value from the symbol table. The
				1895	type and name of the Value are extracted from \p N and used to
				1896	lookup the Value in the correct type plane. If the Value is
				1897	not in the symbol table, this method silently ignores the
				1898	request.</dd>
				1899
				1900	<dt><tt>void remove(Type* Typ)</tt>:</dt>
				1901	<dd> This method removes a named type from the symbol table. The
				1902	name of the type is extracted from \P T and used to look up
				1903	the Type in the type map. If the Type is not in the symbol
				1904	table, this method silently ignores the request.</dd>
				1905
				1906	<dt><tt>Value* remove(const std::string& Name, Value *Val)</tt>:</dt>
				1907	<dd> Remove a constant or type with the specified name from the
				1908	symbol table.</dd>
				1909
				1910	<dt><tt>Type* remove(const std::string& Name, Type* T)</tt>:</dt>
				1911	<dd> Remove a type with the specified name from the symbol table.
				1912	Returns the removed Type.</dd>
				1913
				1914	<dt><tt>Value *value_remove(const value_iterator& It)</tt>:</dt>
				1915	<dd> Removes a specific value from the symbol table.
				1916	Returns the removed value.</dd>
				1917
				1918	<dt><tt>bool strip()</tt>:</dt>
				1919	<dd> This method will strip the symbol table of its names leaving
				1920	the type and values. </dd>
				1921
				1922	<dt><tt>void clear()</tt>:</dt>
				1923	<dd>Empty the symbol table completely.</dd>
				1924	</dl>
				1925
				1926	<h3>Iteration</h3>
				1927	<p>The following functions describe three types of iterators you can obtain
				1928	the beginning or end of the sequence for both const and non-const. It is
				1929	important to keep track of the different kinds of iterators. There are
				1930	three idioms worth pointing out:</p>
Reid Spencer	d3f876c	2004-11-01 08:19:36 +0000	[diff] [blame]	1931	<table>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1932	<tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>
				1933	<tr>
Reid Spencer	d3f876c	2004-11-01 08:19:36 +0000	[diff] [blame]	1934	<td align="left">Planes Of name/Value maps</td><td>PI</td>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1935	<td align="left"><pre><tt>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1936	for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),
Reid Spencer	d3f876c	2004-11-01 08:19:36 +0000	[diff] [blame]	1937	PE = ST.plane_end(); PI != PE; ++PI ) {
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1938	PI->first // This is the Type* of the plane
				1939	PI->second // This is the SymbolTable::ValueMap of name/Value pairs
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1940	</tt></pre></td>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1941	</tr>
				1942	<tr>
Reid Spencer	d3f876c	2004-11-01 08:19:36 +0000	[diff] [blame]	1943	<td align="left">All name/Type Pairs</td><td>TI</td>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1944	<td align="left"><pre><tt>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1945	for (SymbolTable::type_const_iterator TI = ST.type_begin(),
				1946	TE = ST.type_end(); TI != TE; ++TI )
				1947	TI->first // This is the name of the type
				1948	TI->second // This is the Type* value associated with the name
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1949	</tt></pre></td>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1950	</tr>
				1951	<tr>
Reid Spencer	d3f876c	2004-11-01 08:19:36 +0000	[diff] [blame]	1952	<td align="left">name/Value pairs in a plane</td><td>VI</td>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1953	<td align="left"><pre><tt>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1954	for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),
				1955	VE = ST.value_end(SomeType); VI != VE; ++VI )
				1956	VI->first // This is the name of the Value
				1957	VI->second // This is the Value* value associated with the name
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1958	</tt></pre></td>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1959	</tr>
				1960	</table>
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	1961
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	1962	<p>Using the recommended iterator names and idioms will help you avoid
				1963	making mistakes. Of particular note, make sure that whenever you use
				1964	value_begin(SomeType) that you always compare the resulting iterator
				1965	with value_end(SomeType) not value_end(SomeOtherType) or else you
				1966	will loop infinitely.</p>
				1967
				1968	<dl>
				1969
				1970	<dt><tt>plane_iterator plane_begin()</tt>:</dt>
				1971	<dd>Get an iterator that starts at the beginning of the type planes.
				1972	The iterator will iterate over the Type/ValueMap pairs in the
				1973	type planes. </dd>
				1974
				1975	<dt><tt>plane_const_iterator plane_begin() const</tt>:</dt>
				1976	<dd>Get a const_iterator that starts at the beginning of the type
				1977	planes. The iterator will iterate over the Type/ValueMap pairs
				1978	in the type planes. </dd>
				1979
				1980	<dt><tt>plane_iterator plane_end()</tt>:</dt>
				1981	<dd>Get an iterator at the end of the type planes. This serves as
				1982	the marker for end of iteration over the type planes.</dd>
				1983
				1984	<dt><tt>plane_const_iterator plane_end() const</tt>:</dt>
				1985	<dd>Get a const_iterator at the end of the type planes. This serves as
				1986	the marker for end of iteration over the type planes.</dd>
				1987
				1988	<dt><tt>value_iterator value_begin(const Type *Typ)</tt>:</dt>
				1989	<dd>Get an iterator that starts at the beginning of a type plane.
				1990	The iterator will iterate over the name/value pairs in the type plane.
				1991	Note: The type plane must already exist before using this.</dd>
				1992
				1993	<dt><tt>value_const_iterator value_begin(const Type *Typ) const</tt>:</dt>
				1994	<dd>Get a const_iterator that starts at the beginning of a type plane.
				1995	The iterator will iterate over the name/value pairs in the type plane.
				1996	Note: The type plane must already exist before using this.</dd>
				1997
				1998	<dt><tt>value_iterator value_end(const Type *Typ)</tt>:</dt>
				1999	<dd>Get an iterator to the end of a type plane. This serves as the marker
				2000	for end of iteration of the type plane.
				2001	Note: The type plane must already exist before using this.</dd>
				2002
				2003	<dt><tt>value_const_iterator value_end(const Type *Typ) const</tt>:</dt>
				2004	<dd>Get a const_iterator to the end of a type plane. This serves as the
				2005	marker for end of iteration of the type plane.
				2006	Note: the type plane must already exist before using this.</dd>
				2007
				2008	<dt><tt>type_iterator type_begin()</tt>:</dt>
				2009	<dd>Get an iterator to the start of the name/Type map.</dd>
				2010
				2011	<dt><tt>type_const_iterator type_begin() cons</tt>:</dt>
				2012	<dd> Get a const_iterator to the start of the name/Type map.</dd>
				2013
				2014	<dt><tt>type_iterator type_end()</tt>:</dt>
				2015	<dd>Get an iterator to the end of the name/Type map. This serves as the
				2016	marker for end of iteration of the types.</dd>
				2017
				2018	<dt><tt>type_const_iterator type_end() const</tt>:</dt>
				2019	<dd>Get a const-iterator to the end of the name/Type map. This serves
				2020	as the marker for end of iteration of the types.</dd>
				2021
				2022	<dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>
				2023	<dd>This method returns a plane_const_iterator for iteration over
				2024	the type planes starting at a specific plane, given by \p Ty.</dd>
				2025
				2026	<dt><tt>plane_iterator find( const Type* Typ </tt>:</dt>
				2027	<dd>This method returns a plane_iterator for iteration over the
				2028	type planes starting at a specific plane, given by \p Ty.</dd>
				2029
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	2030	</dl>
				2031	</div>
				2032
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	2033	<!-- *********************************************************************** -->
Misha Brukman	13fd15c	2004-01-15 00:14:41 +0000	[diff] [blame]	2034	<hr>
				2035	<address>
				2036	<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
				2037	src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
				2038	<a href="http://validator.w3.org/check/referer"><img
				2039	src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
				2040
				2041	<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
				2042	<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
				2043	<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
				2044	Last modified: $Date$
				2045	</address>
				2046
Chris Lattner	261efe9	2003-11-25 01:02:51 +0000	[diff] [blame]	2047	</body>
				2048	</html>
Reid Spencer	096603a	2004-05-26 08:41:35 +0000	[diff] [blame]	2049	<!-- vim: sw=2 noai
				2050	-->