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				2	<html><head><title>LLVM Programmer's Manual</title></head>
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				4	<body bgcolor=white>
				5
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	6	<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
				7	<tr><td>  <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM Programmer's Manual</b></font></td>
				8	</tr></table>
				9
				10	<ol>
				11	<li><a href="#introduction">Introduction</a>
				12	<li><a href="#general">General Information</a>
				13	<ul>
				14	<li><a href="#stl">The C++ Standard Template Library</a>
				15	<li>The isa<>, cast<> and dyn_cast<> templates
				16	</ul>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	17	<li><a href="#common">Helpful Hints for Common Operations</a>
				18	<ul>
				19	<li><a href="#inspection">Basic Inspection and Traversal Routines</a>
				20	<ul>
				21	<li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
				22	in a <tt>Function</tt></a>
				23	<li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
				24	in a <tt>BasicBlock</tt></a>
				25	<li><a href="#iterate_convert">Turning an iterator into a class
				26	pointer</a>
Chris Lattner	f1ebdc3	2002-09-06 22:09:21 +0000	[diff] [blame]	27	<li><a href="#iterate_complex">Finding call sites: a more complex
				28	example</a>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	29	</ul>
				30	<li><a href="#simplechanges">Making simple changes</a>
				31	<ul>
				32	<li>Creating and inserting new <tt>Instruction</tt>s
				33	<li>Deleting <tt>Instruction</tt>s
				34	<li>Replacing an <tt>Instruction</tt> with another <tt>Value</tt>
				35	</ul>
				36	<!--
				37	<li>Working with the Control Flow Graph
				38	<ul>
				39	<li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
				40	<li>
				41	<li>
				42	</ul>
				43	-->
				44	<li>Useful LLVM APIs
				45	<ul>
				46	<li>isa<>, cast<>, and dyn_cast<> templates
				47	<!--
				48	<li>The general graph API
				49	<li>The <tt>InstVisitor</tt> template
				50	<li>The DEBUG() macro
				51	<li>The <tt>Statistic</tt> template
				52	-->
				53	</ul>
				54	<!--
				55	<li>Useful related topics
				56	<ul>
				57	<li>The <tt>-time-passes</tt> option
				58	<li>How to use the LLVM Makefile system
				59	<li>How to write a regression test
				60	<li>
				61	</ul>
				62	-->
				63	</ul>
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	64	<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	65	<ul>
				66	<li><a href="#Value">The <tt>Value</tt> class</a>
				67	<ul>
				68	<li><a href="#User">The <tt>User</tt> class</a>
				69	<ul>
				70	<li><a href="#Instruction">The <tt>Instruction</tt> class</a>
				71	<ul>
				72	<li>
				73	<li>
				74	</ul>
				75	<li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
				76	<ul>
				77	<li><a href="#BasicBlock">The <tt>BasicBlock</tt> class</a>
				78	<li><a href="#Function">The <tt>Function</tt> class</a>
				79	<li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a>
				80	</ul>
				81	<li><a href="#Module">The <tt>Module</tt> class</a>
				82	<li><a href="#Constant">The <tt>Constant</tt> class</a>
				83	<ul>
				84	<li>
				85	<li>
				86	</ul>
				87	</ul>
				88	<li><a href="#Type">The <tt>Type</tt> class</a>
				89	<li><a href="#Argument">The <tt>Argument</tt> class</a>
				90	</ul>
				91	<li>The <tt>SymbolTable</tt> class
				92	<li>The <tt>ilist</tt> and <tt>iplist</tt> classes
				93	<ul>
				94	<li>Creating, inserting, moving and deleting from LLVM lists
				95	</ul>
				96	<li>Important iterator invalidation semantics to be aware of
				97	</ul>
				98
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	99	<p><b>Written by <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>
Chris Lattner	f1ebdc3	2002-09-06 22:09:21 +0000	[diff] [blame]	100	<a href="mailto:sabre@nondot.org">Chris Lattner</a>, and
				101	<a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b><p>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	102	</ol>
				103
				104
				105	<!-- *********************************************************************** -->
				106	<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
				107	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
				108	<a name="introduction">Introduction
				109	</b></font></td></tr></table><ul>
				110	<!-- *********************************************************************** -->
				111
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	112	This document is meant to highlight some of the important classes and interfaces
				113	available in the LLVM source-base. This manual is not intended to explain what
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	114	LLVM is, how it works, and what LLVM code looks like. It assumes that you know
				115	the basics of LLVM and are interested in writing transformations or otherwise
				116	analyzing or manipulating the code.<p>
				117
				118	This document should get you oriented so that you can find your way in the
				119	continuously growing source code that makes up the LLVM infrastructure. Note
				120	that this manual is not intended to serve as a replacement for reading the
				121	source code, so if you think there should be a method in one of these classes to
				122	do something, but it's not listed, check the source. Links to the <a
				123	href="/doxygen/">doxygen</a> sources are provided to make this as easy as
				124	possible.<p>
				125
				126	The first section of this document describes general information that is useful
				127	to know when working in the LLVM infrastructure, and the second describes the
				128	Core LLVM classes. In the future this manual will be extended with information
				129	describing how to use extension libraries, such as dominator information, CFG
				130	traversal routines, and useful utilities like the <tt><a
				131	href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.<p>
				132
				133
				134	<!-- *********************************************************************** -->
				135	</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
				136	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
				137	<a name="general">General Information
				138	</b></font></td></tr></table><ul>
				139	<!-- *********************************************************************** -->
				140
				141	This section contains general information that is useful if you are working in
				142	the LLVM source-base, but that isn't specific to any particular API.<p>
				143
				144
				145	<!-- ======================================================================= -->
				146	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				147	<tr><td> </td><td width="100%">
				148	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				149	<a name="stl">The C++ Standard Template Library</a>
				150	</b></font></td></tr></table><ul>
				151
				152	LLVM makes heavy use of the C++ Standard Template Library (STL), perhaps much
				153	more than you are used to, or have seen before. Because of this, you might want
				154	to do a little background reading in the techniques used and capabilities of the
				155	library. There are many good pages that discuss the STL, and several books on
				156	the subject that you can get, so it will not be discussed in this document.<p>
				157
				158	Here are some useful links:<p>
				159	<ol>
				160	<li><a href="http://www.dinkumware.com/htm_cpl/index.html">Dinkumware C++
				161	Library reference</a> - an excellent reference for the STL and other parts of
				162	the standard C++ library.<br>
				163
				164	<li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
				165	Questions</a>
				166
				167	<li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
				168	Contains a useful <a
				169	href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
				170	STL</a>.
				171
				172	<li><a href="http://www.research.att.com/~bs/C++.html">Bjarne Stroustrup's C++
				173	Page</a>
				174
				175	</ol><p>
				176
				177	You are also encouraged to take a look at the <a
				178	href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
				179	to write maintainable code more than where to put your curly braces.<p>
				180
				181
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	182
Chris Lattner	b99344f	2002-09-06 16:40:10 +0000	[diff] [blame]	183	<!-- *********************************************************************** -->
				184	</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
				185	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
				186	<a name="common">Helpful Hints for Common Operations
				187	</b></font></td></tr></table><ul>
				188	<!-- *********************************************************************** -->
				189
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	190	This section describes how to perform some very simple transformations of LLVM
				191	code. This is meant to give examples of common idioms used, showing the
				192	practical side of LLVM transformations.<p>
				193
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	194	Because this is a "how-to" section, you should also read about the main classes
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	195	that you will be working with. The <a href="#coreclasses">Core LLVM Class
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	196	Hierarchy Reference</a> contains details and descriptions of the main classes
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	197	that you should know about.<p>
				198
				199	<!-- NOTE: this section should be heavy on example code -->
				200
				201
				202	<!-- ======================================================================= -->
				203	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				204	<tr><td> </td><td width="100%">
				205	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				206	<a name="inspection">Basic Inspection and Traversal Routines</a>
				207	</b></font></td></tr></table><ul>
				208
				209
				210	<!-- LLVM has heirarchical representation: Module, Function, BasicBlock,
				211	Instruction. Common patterns for all levels. -->
				212
				213	<!-- _______________________________________________________________________ -->
				214	</ul><h4><a name="iterate_function"><hr size=0>Iterating over the
				215	<tt>BasicBlock</tt>s in a <tt>Function</tt> </h4><ul>
				216
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	217	It's quite common to have a <tt>Function</tt> instance that you'd like
				218	to transform in some way; in particular, you'd like to manipulate its
				219	<tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over
				220	all of the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>.
				221	The following is an example that prints the name of a
				222	<tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s it
				223	contains:
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	224
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	225	<pre>
				226	// func is a pointer to a Function instance
				227	for(Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {
				228
				229	// print out the name of the basic block if it has one, and then the
				230	// number of instructions that it contains
				231
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	232	cerr <&lt "Basic block (name=" <&lt i->getName() << ") has "
				233	<&lt i->size() <&lt " instructions.\n";
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	234	}
				235	</pre>
				236
				237	Note that i can be used as if it were a pointer for the purposes of
				238	invoking member functions of the <tt>Instruction</tt> class. This is
				239	because the indirection operator is overloaded for the iterator
				240	classes. In the above code, the expression <tt>i->size()</tt> is
				241	exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	242
				243	<!-- _______________________________________________________________________ -->
				244	</ul><h4><a name="iterate_basicblock"><hr size=0>Iterating over the
				245	<tt>Instruction</tt>s in a <tt>BasicBlock</tt> </h4><ul>
				246
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	247	Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, it's
				248	easy to iterate over the individual instructions that make up
				249	<tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in
				250	a <tt>BasicBlock</tt>:
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	251
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	252	<pre>
				253	// blk is a pointer to a BasicBlock instance
Chris Lattner	2b76306	2002-09-06 22:51:10 +0000	[diff] [blame]	254	for(BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i) {
				255	// the next statement works since operator<<(ostream&,...)
				256	// is overloaded for Instruction&
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	257
Chris Lattner	2b76306	2002-09-06 22:51:10 +0000	[diff] [blame]	258	cerr << *i << endl;
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	259	}
				260	</pre>
				261
				262	However, this isn't really the best way to print out the contents of a
				263	<tt>BasicBlock</tt>! Since the ostream operators are overloaded for
				264	virtually anything you'll care about, you could have just invoked the
Chris Lattner	2b76306	2002-09-06 22:51:10 +0000	[diff] [blame]	265	print routine on the basic block itself: <tt>cerr << *blk <<
				266	"\n";</tt>.<p>
				267
				268	Note that currently operator<< is implemented for <tt>Value*</tt>, so it
				269	will print out the contents of the pointer, instead of
				270	the pointer value you might expect. This is a deprecated interface that will
				271	be removed in the future, so it's best not to depend on it. To print out the
				272	pointer value for now, you must cast to <tt>void*</tt>.<p>
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	273
				274	<!-- _______________________________________________________________________ -->
				275	</ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
				276	pointer </h4><ul>
				277
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	278	Sometimes, it'll be useful to grab a reference (or pointer) to a class
				279	instance when all you've got at hand is an iterator. Well, extracting
				280	a reference or a pointer from an iterator is very straightforward.
				281	Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
				282	<tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
				283
				284	<pre>
Chris Lattner	83b5ee0	2002-09-06 22:12:58 +0000	[diff] [blame]	285	Instruction& inst = *i; // grab reference to instruction reference
				286	Instruction* pinst = &*i; // grab pointer to instruction reference
				287	const Instruction& inst = *j;
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	288	</pre>
				289	However, the iterators you'll be working with in the LLVM framework
				290	are special: they will automatically convert to a ptr-to-instance type
				291	whenever they need to. Instead of dereferencing the iterator and then
				292	taking the address of the result, you can simply assign the iterator
				293	to the proper pointer type and you get the dereference and address-of
				294	operation as a result of the assignment (behind the scenes, this is a
				295	result of overloading casting mechanisms). Thus the last line of the
				296	last example,
				297
Chris Lattner	83b5ee0	2002-09-06 22:12:58 +0000	[diff] [blame]	298	<pre>Instruction* pinst = &*i;</pre>
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	299
				300	is semantically equivalent to
				301
				302	<pre>Instruction* pinst = i;</pre>
				303
				304	<b>Caveat emptor</b>: The above syntax works <i>only</i> when you're
				305	<i>not</i> working with <tt>dyn_cast</tt>. The template definition of
				306	<tt>dyn_cast</tt> isn't implemented to handle this yet, so you'll
				307	still need the following in order for things to work properly:
				308
				309	<pre>
				310	BasicBlock::iterator bbi = ...;
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	311	BranchInst* b = dyn_cast<BranchInst>(&amp*bbi);
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	312	</pre>
				313
				314	The following code snippet illustrates use of the conversion
				315	constructors provided by LLVM iterators. By using these, you can
				316	explicitly grab the iterator of something without actually obtaining
				317	it via iteration over some structure:
				318
				319	<pre>
				320	void printNextInstruction(Instruction* inst) {
				321	BasicBlock::iterator it(inst);
				322	++it; // after this line, it refers to the instruction after *inst.
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	323	if(it != inst->getParent()->end()) cerr <&lt *it <&lt endl;
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	324	}
				325	</pre>
				326
				327	Of course, this example is strictly pedagogical, because it'd be
				328	better to do something like
				329
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	330	<pre>if(inst->getNext()) cerr <&lt inst->getNext() <&lt endl;</pre>
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	331
				332
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	333	<!-- dereferenced iterator = Class &
				334	iterators have converting constructor for 'Class *'
				335	iterators automatically convert to 'Class *' except in dyn_cast<> case
				336	-->
				337
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	338	<!--
				339	_______________________________________________________________________
				340	--> </ul><h4><a name="iterate_complex"><hr size=0>Finding call sites:
				341	a slightly more complex example
				342	</h4><ul>
				343
				344	Say that you're writing a FunctionPass and would like to count all the
				345	locations in the entire module (that is, across every <tt>Function</tt>)
				346	where a certain function named foo (that takes an int and returns an
				347	int) is called. As you'll learn later, you may want to use an
				348	<tt>InstVisitor</tt> to accomplish this in a much more straightforward
				349	manner, but this example will allow us to explore how you'd do it if
				350	you didn't have <tt>InstVisitor</tt> around. In pseudocode, this is
				351	what we want to do:
				352
				353	<pre>
				354	initialize callCounter to zero
				355	for each Function f in the Module
				356	for each BasicBlock b in f
				357	for each Instruction i in b
				358	if(i is a CallInst and foo is the function it calls)
				359	increment callCounter
				360	</pre>
				361
				362	And the actual code is (remember, since we're writing a
				363	<tt>FunctionPass</tt> our <tt>FunctionPass</tt>-derived class simply
				364	has to override the <tt>runOnFunction</tt> method...):
				365
				366	<pre>
				367
				368	// Assume callCounter is a private member of the pass class being written,
				369	// and has been initialized in the pass class constructor.
				370
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	371	virtual runOnFunction(Function&amp F) {
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	372
				373	// Remember, we assumed that the signature of foo was "int foo(int)";
				374	// the first thing we'll do is grab the pointer to that function (as a
				375	// Function*) so we can use it later when we're examining the
				376	// parameters of a CallInst. All of the code before the call to
				377	// Module::getOrInsertFunction() is in preparation to do symbol-table
				378	// to find the function pointer.
				379
				380	vector<const Type*> params;
				381	params.push_back(Type::IntTy);
				382	const FunctionType* fooType = FunctionType::get(Type::IntTy, params);
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	383	Function* foo = F.getParent()->getOrInsertFunction("foo", fooType);
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	384
				385	// Start iterating and (as per the pseudocode), increment callCounter.
				386
				387	for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	388	for(BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {
				389	if(CallInst* callInst = dyn_cast<CallInst>(&*inst)) {
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	390	// we know we've encountered a call instruction, so we
				391	// need to determine if it's a call to foo or not
				392
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	393	if(callInst->getCalledFunction() == foo)
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	394	++callCounter;
				395	}
				396	}
				397	}
				398	}
				399	</pre>
				400
				401	We could then print out the value of callCounter (if we wanted to)
				402	inside the doFinalization method of our FunctionPass.
Chris Lattner	ae7f759	2002-09-06 18:31:18 +0000	[diff] [blame]	403
				404
				405	<!-- ======================================================================= -->
				406	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				407	<tr><td> </td><td width="100%">
				408	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				409	<a name="simplechanges">Making simple changes</a>
				410	</b></font></td></tr></table><ul>
				411
				412	<!-- Value::replaceAllUsesWith
				413	User::replaceUsesOfWith
				414	Point out: include/llvm/Transforms/Utils/
				415	especially BasicBlockUtils.h with:
				416	ReplaceInstWithValue, ReplaceInstWithInst
				417
				418	-->
Chris Lattner	b99344f	2002-09-06 16:40:10 +0000	[diff] [blame]	419
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	420
				421	<!-- *********************************************************************** -->
				422	</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
				423	<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	424	<a name="coreclasses">The Core LLVM Class Hierarchy Reference
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	425	</b></font></td></tr></table><ul>
				426	<!-- *********************************************************************** -->
				427
				428	The Core LLVM classes are the primary means of representing the program being
				429	inspected or transformed. The core LLVM classes are defined in header files in
				430	the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
				431	directory.<p>
				432
				433
				434	<!-- ======================================================================= -->
				435	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				436	<tr><td> </td><td width="100%">
				437	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				438	<a name="Value">The <tt>Value</tt> class</a>
				439	</b></font></td></tr></table><ul>
				440
				441	<tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
				442	doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
				443
				444
				445	The <tt>Value</tt> class is the most important class in LLVM Source base. It
				446	represents a typed value that may be used (among other things) as an operand to
				447	an instruction. There are many different types of <tt>Value</tt>s, such as <a
				448	href="#Constant"><tt>Constant</tt></a>s, <a
				449	href="#Argument"><tt>Argument</tt></a>s, and even <a
				450	href="#Instruction"><tt>Instruction</tt></a>s and <a
				451	href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
				452
				453	A particular <tt>Value</tt> may be used many times in the LLVM representation
				454	for a program. For example, an incoming argument to a function (represented
				455	with an instance of the <a href="#Argument">Argument</a> class) is "used" by
				456	every instruction in the function that references the argument. To keep track
				457	of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
				458	href="#User"><tt>User</tt></a>s that is using it (the <a
				459	href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
				460	graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
Joel Stanley	9b96c44	2002-09-06 21:55:13 +0000	[diff] [blame]	461	def-use information in the program, and is accessible through the <tt>use_</tt>*
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	462	methods, shown below.<p>
				463
				464	Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
				465	this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
				466	method. <a name="#nameWarning">In addition, all LLVM values can be named. The
				467	"name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
				468
				469	<pre>
				470	%<b>foo</b> = add int 1, 2
				471	</pre>
				472
				473	The name of this instruction is "foo". <b>NOTE</b> that the name of any value
				474	may be missing (an empty string), so names should <b>ONLY</b> be used for
				475	debugging (making the source code easier to read, debugging printouts), they
				476	should not be used to keep track of values or map between them. For this
				477	purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
				478	instead.<p>
				479
				480	One important aspect of LLVM is that there is no distinction between an SSA
				481	variable and the operation that produces it. Because of this, any reference to
				482	the value produced by an instruction (or the value available as an incoming
				483	argument, for example) is represented as a direct pointer to the class that
				484	represents this value. Although this may take some getting used to, it
				485	simplifies the representation and makes it easier to manipulate.<p>
				486
				487
				488	<!-- _______________________________________________________________________ -->
				489	</ul><h4><a name="m_Value"><hr size=0>Important Public Members of
				490	the <tt>Value</tt> class</h4><ul>
				491
				492	<li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
				493	<tt>Value::use_const_iterator</tt>
				494	- Typedef for const_iterator over the use-list<br>
				495	<tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
				496	<tt>bool use_empty()</tt> - Returns true if there are no users.<br>
				497	<tt>use_iterator use_begin()</tt>
				498	- Get an iterator to the start of the use-list.<br>
				499	<tt>use_iterator use_end()</tt>
				500	- Get an iterator to the end of the use-list.<br>
				501	<tt><a href="#User">User</a> *use_back()</tt>
				502	- Returns the last element in the list.<p>
				503
				504	These methods are the interface to access the def-use information in LLVM. As with all other iterators in LLVM, the naming conventions follow the conventions defined by the <a href="#stl">STL</a>.<p>
				505
				506	<li><tt><a href="#Type">Type</a> *getType() const</tt><p>
				507	This method returns the Type of the Value.
				508
				509	<li><tt>bool hasName() const</tt><br>
				510	<tt>std::string getName() const</tt><br>
				511	<tt>void setName(const std::string &Name)</tt><p>
				512
				513	This family of methods is used to access and assign a name to a <tt>Value</tt>,
				514	be aware of the <a href="#nameWarning">precaution above</a>.<p>
				515
				516
				517	<li><tt>void replaceAllUsesWith(Value *V)</tt><p>
				518
				519	This method traverses the use list of a <tt>Value</tt> changing all <a
				520	href="#User"><tt>User</tt>'s</a> of the current value to refer to "<tt>V</tt>"
				521	instead. For example, if you detect that an instruction always produces a
				522	constant value (for example through constant folding), you can replace all uses
				523	of the instruction with the constant like this:<p>
				524
				525	<pre>
				526	Inst->replaceAllUsesWith(ConstVal);
				527	</pre><p>
				528
				529
				530
				531	<!-- ======================================================================= -->
				532	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				533	<tr><td> </td><td width="100%">
				534	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				535	<a name="User">The <tt>User</tt> class</a>
				536	</b></font></td></tr></table><ul>
				537
				538	<tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
				539	doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
				540	Superclass: <a href="#Value"><tt>Value</tt></a><p>
				541
				542
				543	The <tt>User</tt> class is the common base class of all LLVM nodes that may
				544	refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
				545	that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
				546	referring to. The <tt>User</tt> class itself is a subclass of
				547	<tt>Value</tt>.<p>
				548
				549	The operands of a <tt>User</tt> point directly to the LLVM <a
				550	href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
				551	Single Assignment (SSA) form, there can only be one definition referred to,
				552	allowing this direct connection. This connection provides the use-def
				553	information in LLVM.<p>
				554
				555	<!-- _______________________________________________________________________ -->
				556	</ul><h4><a name="m_User"><hr size=0>Important Public Members of
				557	the <tt>User</tt> class</h4><ul>
				558
				559	The <tt>User</tt> class exposes the operand list in two ways: through an index
				560	access interface and through an iterator based interface.<p>
				561
				562	<li><tt>Value *getOperand(unsigned i)</tt><br>
				563	<tt>unsigned getNumOperands()</tt><p>
				564
				565	These two methods expose the operands of the <tt>User</tt> in a convenient form
				566	for direct access.<p>
				567
				568	<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
				569	<tt>User::op_const_iterator</tt>
				570	<tt>use_iterator op_begin()</tt>
				571	- Get an iterator to the start of the operand list.<br>
				572	<tt>use_iterator op_end()</tt>
				573	- Get an iterator to the end of the operand list.<p>
				574
				575	Together, these methods make up the iterator based interface to the operands of
				576	a <tt>User</tt>.<p>
				577
				578
				579
				580	<!-- ======================================================================= -->
				581	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				582	<tr><td> </td><td width="100%">
				583	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				584	<a name="Instruction">The <tt>Instruction</tt> class</a>
				585	</b></font></td></tr></table><ul>
				586
				587	<tt>#include "<a
				588	href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
				589	doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
				590	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				591	href="#Value"><tt>Value</tt></a><p>
				592
				593	The <tt>Instruction</tt> class is the common base class for all LLVM
				594	instructions. It provides only a few methods, but is a very commonly used
				595	class. The primary data tracked by the <tt>Instruction</tt> class itself is the
				596	opcode (instruction type) and the parent <a
				597	href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
				598	into. To represent a specific type of instruction, one of many subclasses of
				599	<tt>Instruction</tt> are used.<p>
				600
				601	Because the <tt>Instruction</tt> class subclasses the <a
				602	href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
				603	way as for other <a href="#User"><tt>User</tt></a>s (with the
				604	<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
				605	<tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
				606
				607
				608	<!-- _______________________________________________________________________ -->
				609	</ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
				610	the <tt>Instruction</tt> class</h4><ul>
				611
				612	<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
				613
				614	Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
				615	<tt>Instruction</tt> is embedded into.<p>
				616
				617	<li><tt>bool hasSideEffects()</tt><p>
				618
				619	Returns true if the instruction has side effects, i.e. it is a <tt>call</tt>,
				620	<tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
				621
				622	<li><tt>unsigned getOpcode()</tt><p>
				623
				624	Returns the opcode for the <tt>Instruction</tt>.<p>
				625
				626	<!--
				627
				628	\subsection{Subclasses of Instruction :}
				629	\begin{itemize}
				630	<li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
				631	\begin{itemize}
				632	<li><tt>bool swapOperands()</tt>: Exchange the two operands to this instruction. If the instruction cannot be reversed (i.e. if it's a Div), it returns true.
				633	\end{itemize}
				634	<li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
				635	\begin{itemize}
				636	<li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
				637	<li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
				638	<li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
				639	\end{itemize}
				640
				641	<li>PHINode : This represents the PHI instructions in the SSA form.
				642	\begin{itemize}
				643	<li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
				644	<li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
				645	<li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
				646	<li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
				647	<li><tt> void addIncoming(Value D, BasicBlock BB)</tt>:
				648	Add an incoming value to the end of the PHI list
				649	<li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
				650	Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
				651	\end{itemize}
				652	<li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
				653	<li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
				654	\begin{itemize}
				655	<li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
				656	\end{itemize}
				657	<li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
				658	\begin{itemize}
				659	<li><tt>Value * getPointerOperand ()</tt>: Returns the Pointer Operand which is typically the 0th operand.
				660	\end{itemize}
				661	<li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
				662	\begin{itemize}
				663	<li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
				664	<li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
				665	<li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
				666	\end{itemize}
				667
				668	\end{itemize}
				669
				670	-->
				671
				672
				673	<!-- ======================================================================= -->
				674	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				675	<tr><td> </td><td width="100%">
				676	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				677	<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
				678	</b></font></td></tr></table><ul>
				679
				680	<tt>#include "<a
				681	href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
				682	doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
				683	Superclass: <a href="#Value"><tt>Value</tt></a><p>
				684
				685
				686	This class represents a single entry multiple exit section of the code, commonly
				687	known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
				688	maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
				689	the body of the block. Matching the language definition, the last element of
				690	this list of instructions is always a terminator instruction (a subclass of the
				691	<a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
				692
				693	In addition to tracking the list of instructions that make up the block, the
				694	<tt>BasicBlock</tt> class also keeps track of the <a
				695	href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
				696
				697	Note that <tt>BasicBlock</tt>s themselves are <a
				698	href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
				699	like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
				700	<tt>label</tt>.<p>
				701
				702
				703	<!-- _______________________________________________________________________ -->
				704	</ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
				705	the <tt>BasicBlock</tt> class</h4><ul>
				706
				707	<li><tt>BasicBlock(const std::string &Name = "", <a
				708	href="#Function">Function</a> *Parent = 0)</tt><p>
				709
				710	The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
				711	insertion into a function. The constructor simply takes a name for the new
				712	block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
				713	into. If the <tt>Parent</tt> parameter is specified, the new
				714	<tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
				715	href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
				716	manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
				717
				718	<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
				719	<tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
				720	<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
				721	<tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
				722
				723	These methods and typedefs are forwarding functions that have the same semantics
				724	as the standard library methods of the same names. These methods expose the
				725	underlying instruction list of a basic block in a way that is easy to
				726	manipulate. To get the full complement of container operations (including
				727	operations to update the list), you must use the <tt>getInstList()</tt>
				728	method.<p>
				729
				730	<li><tt>BasicBlock::InstListType &getInstList()</tt><p>
				731
				732	This method is used to get access to the underlying container that actually
				733	holds the Instructions. This method must be used when there isn't a forwarding
				734	function in the <tt>BasicBlock</tt> class for the operation that you would like
				735	to perform. Because there are no forwarding functions for "updating"
				736	operations, you need to use this if you want to update the contents of a
				737	<tt>BasicBlock</tt>.<p>
				738
				739	<li><tt><A href="#Function">Function</a> *getParent()</tt><p>
				740
				741	Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
				742	embedded into, or a null pointer if it is homeless.<p>
				743
				744	<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
				745
				746	Returns a pointer to the terminator instruction that appears at the end of the
				747	<tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
				748	instruction in the block is not a terminator, then a null pointer is
				749	returned.<p>
				750
				751
				752	<!-- ======================================================================= -->
				753	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				754	<tr><td> </td><td width="100%">
				755	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				756	<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
				757	</b></font></td></tr></table><ul>
				758
				759	<tt>#include "<a
				760	href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
				761	doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
				762	Superclasses: <a href="#User"><tt>User</tt></a>, <a
				763	href="#Value"><tt>Value</tt></a><p>
				764
				765	Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
				766	href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
				767	visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
				768	Because they are visible at global scope, they are also subject to linking with
				769	other globals defined in different translation units. To control the linking
				770	process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
				771	<tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
				772
				773	If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
				774	<tt>static</tt> in C), it is not visible to code outside the current translation
				775	unit, and does not participate in linking. If it has external linkage, it is
				776	visible to external code, and does participate in linking. In addition to
				777	linkage information, <tt>GlobalValue</tt>s keep track of which <a
				778	href="#Module"><tt>Module</tt></a> they are currently part of.<p>
				779
				780	Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
				781	their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
				782	always a pointer to its contents. This is explained in the LLVM Language
				783	Reference Manual.<p>
				784
				785
				786	<!-- _______________________________________________________________________ -->
				787	</ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
				788	the <tt>GlobalValue</tt> class</h4><ul>
				789
				790	<li><tt>bool hasInternalLinkage() const</tt><br>
				791	<tt>bool hasExternalLinkage() const</tt><br>
				792	<tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
				793
				794	These methods manipulate the linkage characteristics of the
				795	<tt>GlobalValue</tt>.<p>
				796
				797	<li><tt><a href="#Module">Module</a> *getParent()</tt><p>
				798
				799	This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
				800	currently embedded into.<p>
				801
				802
				803
				804	<!-- ======================================================================= -->
				805	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				806	<tr><td> </td><td width="100%">
				807	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				808	<a name="Function">The <tt>Function</tt> class</a>
				809	</b></font></td></tr></table><ul>
				810
				811	<tt>#include "<a
				812	href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
				813	doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
				814	Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
				815	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
				816
				817	The <tt>Function</tt> class represents a single procedure in LLVM. It is
				818	actually one of the more complex classes in the LLVM heirarchy because it must
				819	keep track of a large amount of data. The <tt>Function</tt> class keeps track
				820	of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
				821	href="#Argument"><tt>Argument</tt></a>s, and a <a
				822	href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
				823
				824	The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
				825	used part of <tt>Function</tt> objects. The list imposes an implicit ordering
				826	of the blocks in the function, which indicate how the code will be layed out by
				827	the backend. Additionally, the first <a
				828	href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
				829	<tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
				830	block. There are no implicit exit nodes, and in fact there may be multiple exit
				831	nodes from a single <tt>Function</tt>. If the <a
				832	href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
				833	the <tt>Function</tt> is actually a function declaration: the actual body of the
				834	function hasn't been linked in yet.<p>
				835
				836	In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
				837	<tt>Function</tt> class also keeps track of the list of formal <a
				838	href="#Argument"><tt>Argument</tt></a>s that the function receives. This
				839	container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
				840	nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
				841	the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
				842
				843	The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
				844	feature that is only used when you have to look up a value by name. Aside from
				845	that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
				846	make sure that there are not conflicts between the names of <a
				847	href="#Instruction"><tt>Instruction</tt></a>s, <a
				848	href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
				849	href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
				850
				851
				852	<!-- _______________________________________________________________________ -->
				853	</ul><h4><a name="m_Function"><hr size=0>Important Public Members of
				854	the <tt>Function</tt> class</h4><ul>
				855
				856	<li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &N = "")</tt><p>
				857
				858	Constructor used when you need to create new <tt>Function</tt>s to add the the
				859	program. The constructor must specify the type of the function to create and
				860	whether or not it should start out with internal or external linkage.<p>
				861
				862	<li><tt>bool isExternal()</tt><p>
				863
				864	Return whether or not the <tt>Function</tt> has a body defined. If the function
				865	is "external", it does not have a body, and thus must be resolved by linking
				866	with a function defined in a different translation unit.<p>
				867
				868
				869	<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
				870	<tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
				871	<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
				872	<tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
				873
				874	These are forwarding methods that make it easy to access the contents of a
				875	<tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
				876	list.<p>
				877
				878	<li><tt>Function::BasicBlockListType &getBasicBlockList()</tt><p>
				879
				880	Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
				881	neccesary to use when you need to update the list or perform a complex action
				882	that doesn't have a forwarding method.<p>
				883
				884
				885	<li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
				886	<tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
				887	<tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
				888	<tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
				889
				890	These are forwarding methods that make it easy to access the contents of a
				891	<tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
				892
				893	<li><tt>Function::ArgumentListType &getArgumentList()</tt><p>
				894
				895	Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
				896	neccesary to use when you need to update the list or perform a complex action
				897	that doesn't have a forwarding method.<p>
				898
				899
				900
				901	<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
				902
				903	Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
				904	function. Because the entry block for the function is always the first block,
				905	this returns the first block of the <tt>Function</tt>.<p>
				906
				907	<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
				908	<tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
				909
				910	This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
				911	and returns the return type of the function, or the <a
				912	href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
				913
				914
				915	<li><tt>bool hasSymbolTable() const</tt><p>
				916
				917	Return true if the <tt>Function</tt> has a symbol table allocated to it and if
				918	there is at least one entry in it.<p>
				919
				920	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
				921
				922	Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
				923	<tt>Function</tt> or a null pointer if one has not been allocated (because there
				924	are no named values in the function).<p>
				925
				926	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
				927
				928	Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
				929	<tt>Function</tt> or allocate a new <a
				930	href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
				931	should only be used when adding elements to the <a
				932	href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
				933	not left laying around.<p>
				934
				935
				936
				937	<!-- ======================================================================= -->
				938	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				939	<tr><td> </td><td width="100%">
				940	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				941	<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
				942	</b></font></td></tr></table><ul>
				943
				944	<tt>#include "<a
				945	href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
				946	doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
				947	Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
				948	href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
				949
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	950	Global variables are represented with the (suprise suprise)
				951	<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
				952	also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
				953	are always referenced by their address (global values must live in memory, so
				954	their "name" refers to their address). Global variables may have an initial
				955	value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
				956	have an initializer, they may be marked as "constant" themselves (indicating
				957	that their contents never change at runtime).<p>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	958
				959
				960	<!-- _______________________________________________________________________ -->
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	961	</ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
				962	<tt>GlobalVariable</tt> class</h4><ul>
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	963
				964	<li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
				965	isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
				966	&Name = "")</tt><p>
				967
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	968	Create a new global variable of the specified type. If <tt>isConstant</tt> is
				969	true then the global variable will be marked as unchanging for the program, and
				970	if <tt>isInternal</tt> is true the resultant global variable will have internal
				971	linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
				972
				973
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	974	<li><tt>bool isConstant() const</tt><p>
				975
				976	Returns true if this is a global variable is known not to be modified at
				977	runtime.<p>
				978
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	979
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	980	<li><tt>bool hasInitializer()</tt><p>
				981
				982	Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
				983
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	984
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	985	<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
				986
Chris Lattner	0377de4	2002-09-06 14:50:55 +0000	[diff] [blame]	987	Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
				988	this method if there is no initializer.<p>
				989
				990
				991	<!-- ======================================================================= -->
				992	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				993	<tr><td> </td><td width="100%">
				994	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				995	<a name="Module">The <tt>Module</tt> class</a>
				996	</b></font></td></tr></table><ul>
				997
				998	<tt>#include "<a
				999	href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
				1000	doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
				1001
				1002	The <tt>Module</tt> class represents the top level structure present in LLVM
				1003	programs. An LLVM module is effectively either a translation unit of the
				1004	original program or a combination of several translation units merged by the
				1005	linker. The <tt>Module</tt> class keeps track of a list of <a
				1006	href="#Function"><tt>Function</tt></a>s, a list of <a
				1007	href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
				1008	href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
				1009	helpful member functions that try to make common operations easy.<p>
				1010
				1011
				1012	<!-- _______________________________________________________________________ -->
				1013	</ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
				1014	<tt>Module</tt> class</h4><ul>
				1015
				1016	<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
				1017	<tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
				1018	<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
				1019	<tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
				1020
				1021	These are forwarding methods that make it easy to access the contents of a
				1022	<tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
				1023	list.<p>
				1024
				1025	<li><tt>Module::FunctionListType &getFunctionList()</tt><p>
				1026
				1027	Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
				1028	neccesary to use when you need to update the list or perform a complex action
				1029	that doesn't have a forwarding method.<p>
				1030
				1031	<!-- Global Variable -->
				1032	<hr size=0>
				1033
				1034	<li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
				1035	<tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
				1036	<tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
				1037	<tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
				1038
				1039	These are forwarding methods that make it easy to access the contents of a
				1040	<tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
				1041	list.<p>
				1042
				1043	<li><tt>Module::GlobalListType &getGlobalList()</tt><p>
				1044
				1045	Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
				1046	This is neccesary to use when you need to update the list or perform a complex
				1047	action that doesn't have a forwarding method.<p>
				1048
				1049
				1050	<!-- Symbol table stuff -->
				1051	<hr size=0>
				1052
				1053	<li><tt>bool hasSymbolTable() const</tt><p>
				1054
				1055	Return true if the <tt>Module</tt> has a symbol table allocated to it and if
				1056	there is at least one entry in it.<p>
				1057
				1058	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
				1059
				1060	Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
				1061	<tt>Module</tt> or a null pointer if one has not been allocated (because there
				1062	are no named values in the function).<p>
				1063
				1064	<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
				1065
				1066	Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
				1067	<tt>Module</tt> or allocate a new <a
				1068	href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
				1069	should only be used when adding elements to the <a
				1070	href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
				1071	not left laying around.<p>
				1072
				1073
				1074	<!-- Convenience methods -->
				1075	<hr size=0>
				1076
				1077	<li><tt><a href="#Function">Function</a> getFunction(const std::string &Name, const <a href="#FunctionType">FunctionType</a> Ty)</tt><p>
				1078
				1079	Look up the specified function in the <tt>Module</tt> <a
				1080	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
				1081	<tt>null</tt>.<p>
				1082
				1083
				1084	<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
				1085	&Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
				1086
				1087	Look up the specified function in the <tt>Module</tt> <a
				1088	href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
				1089	external declaration for the function and return it.<p>
				1090
				1091
				1092	<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
				1093
				1094	If there is at least one entry in the <a
				1095	href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
				1096	href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
				1097	string.<p>
				1098
				1099
				1100	<li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
				1101	*Ty)</tt><p>
				1102
				1103	Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
				1104	<tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
				1105	is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
				1106	modified.<p>
				1107
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1108
				1109	<!-- ======================================================================= -->
				1110	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				1111	<tr><td> </td><td width="100%">
				1112	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				1113	<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
				1114	</b></font></td></tr></table><ul>
				1115
				1116	Constant represents a base class for different types of constants. It is
				1117	subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
				1118	ConstantArray etc for representing the various types of Constants.<p>
				1119
				1120
				1121	<!-- _______________________________________________________________________ -->
				1122	</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
				1123
				1124	<li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
				1125
				1126
				1127
				1128
				1129	\subsection{Important Subclasses of Constant}
				1130	\begin{itemize}
				1131	<li>ConstantSInt : This subclass of Constant represents a signed integer constant.
				1132	\begin{itemize}
				1133	<li><tt>int64_t getValue () const</tt>: Returns the underlying value of this constant.
				1134	\end{itemize}
				1135	<li>ConstantUInt : This class represents an unsigned integer.
				1136	\begin{itemize}
				1137	<li><tt>uint64_t getValue () const</tt>: Returns the underlying value of this constant.
				1138	\end{itemize}
				1139	<li>ConstantFP : This class represents a floating point constant.
				1140	\begin{itemize}
				1141	<li><tt>double getValue () const</tt>: Returns the underlying value of this constant.
				1142	\end{itemize}
				1143	<li>ConstantBool : This represents a boolean constant.
				1144	\begin{itemize}
				1145	<li><tt>bool getValue () const</tt>: Returns the underlying value of this constant.
				1146	\end{itemize}
				1147	<li>ConstantArray : This represents a constant array.
				1148	\begin{itemize}
				1149	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
				1150	\end{itemize}
				1151	<li>ConstantStruct : This represents a constant struct.
				1152	\begin{itemize}
				1153	<li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
				1154	\end{itemize}
				1155	<li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
				1156	\begin{itemize}
				1157	<li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
				1158	\end{itemize}
				1159	\end{itemize}
				1160
				1161
				1162	<!-- ======================================================================= -->
				1163	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				1164	<tr><td> </td><td width="100%">
				1165	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				1166	<a name="Type">The <tt>Type</tt> class and Derived Types</a>
				1167	</b></font></td></tr></table><ul>
				1168
				1169	Type as noted earlier is also a subclass of a Value class. Any primitive
				1170	type (like int, short etc) in LLVM is an instance of Type Class. All
				1171	other types are instances of subclasses of type like FunctionType,
				1172	ArrayType etc. DerivedType is the interface for all such dervied types
				1173	including FunctionType, ArrayType, PointerType, StructType. Types can have
				1174	names. They can be recursive (StructType). There exists exactly one instance
				1175	of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
				1176
				1177	<!-- _______________________________________________________________________ -->
				1178	</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
				1179
				1180	<li><tt>PrimitiveID getPrimitiveID () const</tt>: Returns the base type of the type.
				1181	<li><tt> bool isSigned () const</tt>: Returns whether an integral numeric type is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is not true for Float and Double.
				1182	<li><tt>bool isUnsigned () const</tt>: Returns whether a numeric type is unsigned. This is not quite the complement of isSigned... nonnumeric types return false as they do with isSigned. This returns true for UByteTy, UShortTy, UIntTy, and ULongTy.
				1183	<li><tt> bool isInteger () const</tt>: Equilivent to isSigned() \|\| isUnsigned(), but with only a single virtual function invocation.
				1184	<li><tt>bool isIntegral () const</tt>: Returns true if this is an integral type, which is either Bool type or one of the Integer types.
				1185
				1186	<li><tt>bool isFloatingPoint ()</tt>: Return true if this is one of the two floating point types.
				1187	<li><tt>bool isRecursive () const</tt>: Returns rue if the type graph contains a cycle.
				1188	<li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if this type can be converted to 'Ty' without any reinterpretation of bits. For example, uint to int.
				1189	<li><tt>bool isPrimitiveType () const</tt>: Returns true if it is a primitive type.
				1190	<li><tt>bool isDerivedType () const</tt>: Returns true if it is a derived type.
				1191	<li><tt>const Type * getContainedType (unsigned i) const</tt>:
				1192	This method is used to implement the type iterator. For derived types, this returns the types 'contained' in the derived type, returning 0 when 'i' becomes invalid. This allows the user to iterate over the types in a struct, for example, really easily.
				1193	<li><tt>unsigned getNumContainedTypes () const</tt>: Return the number of types in the derived type.
				1194
				1195
				1196
				1197	\subsection{Derived Types}
				1198	\begin{itemize}
				1199	<li>SequentialType : This is subclassed by ArrayType and PointerType
				1200	\begin{itemize}
				1201	<li><tt>const Type * getElementType () const</tt>: Returns the type of each of the elements in the sequential type.
				1202	\end{itemize}
				1203	<li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
				1204	\begin{itemize}
				1205	<li><tt>unsigned getNumElements () const</tt>: Returns the number of elements in the array.
				1206	\end{itemize}
				1207	<li>PointerType : Subclass of SequentialType for pointer types.
				1208	<li>StructType : subclass of DerivedTypes for struct types
				1209	<li>FunctionType : subclass of DerivedTypes for function types.
				1210	\begin{itemize}
				1211
				1212	<li><tt>bool isVarArg () const</tt>: Returns true if its a vararg function
				1213	<li><tt> const Type * getReturnType () const</tt>: Returns the return type of the function.
				1214	<li><tt> const ParamTypes &getParamTypes () const</tt>: Returns a vector of parameter types.
				1215	<li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
				1216	<li><tt> const unsigned getNumParams () const</tt>: Returns the number of formal parameters.
				1217	\end{itemize}
				1218	\end{itemize}
				1219
				1220
				1221
				1222
				1223	<!-- ======================================================================= -->
				1224	</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
				1225	<tr><td> </td><td width="100%">
				1226	<font color="#EEEEFF" face="Georgia,Palatino"><b>
				1227	<a name="Argument">The <tt>Argument</tt> class</a>
				1228	</b></font></td></tr></table><ul>
				1229
				1230	This subclass of Value defines the interface for incoming formal arguments to a
				1231	function. A Function maitanis a list of its formal arguments. An argument has a
				1232	pointer to the parent Function.
				1233
				1234
				1235
				1236
				1237	<!-- *********************************************************************** -->
				1238	</ul>
				1239	<!-- *********************************************************************** -->
				1240
				1241	<hr><font size-1>
				1242	<address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
				1243	<a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
				1244	<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
				1245	<!-- hhmts start -->
Joel Stanley	72ef35e	2002-09-06 23:05:12 +0000	[diff] [blame^]	1246	Last modified: Fri Sep 6 18:03:31 EDT 2002
Chris Lattner	9355b47	2002-09-06 02:50:58 +0000	[diff] [blame]	1247	<!-- hhmts end -->
				1248	</font></body></html>