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2<html><head><title>LLVM Programmer's Manual</title></head>
3
4<body bgcolor=white>
5
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]6<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
7<tr><td>&nbsp; <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>
Chris Lattner1d43fd42002-09-09 05:53:21 +0000[diff] [blame]15 <li><a href="#isa">The <tt>isa&lt;&gt;</tt>, <tt>cast&lt;&gt;</tt> and
16 <tt>dyn_cast&lt;&gt;</tt> templates</a>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]17 </ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]18 <li><a href="#common">Helpful Hints for Common Operations</a>
19 <ul>
20 <li><a href="#inspection">Basic Inspection and Traversal Routines</a>
21 <ul>
22 <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
23 in a <tt>Function</tt></a>
24 <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
25 in a <tt>BasicBlock</tt></a>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]26 <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
27 in a <tt>Function</tt></a>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]28 <li><a href="#iterate_convert">Turning an iterator into a class
29 pointer</a>
Chris Lattnerf1ebdc32002-09-06 22:09:21 +0000[diff] [blame]30 <li><a href="#iterate_complex">Finding call sites: a more complex
31 example</a>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]32 <li><a href="#iterate_chains">Iterating over def-use &amp; use-def
33 chains</a>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]34 </ul>
35 <li><a href="#simplechanges">Making simple changes</a>
36 <ul>
37 <li>Creating and inserting new <tt>Instruction</tt>s
38 <li>Deleting <tt>Instruction</tt>s
39 <li>Replacing an <tt>Instruction</tt> with another <tt>Value</tt>
40 </ul>
41<!--
42 <li>Working with the Control Flow Graph
43 <ul>
44 <li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
45 <li>
46 <li>
47 </ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]48 <li>Useful LLVM APIs
49 <ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]50 <li>The general graph API
51 <li>The <tt>InstVisitor</tt> template
52 <li>The DEBUG() macro
53 <li>The <tt>Statistic</tt> template
54-->
55 </ul>
56<!--
57 <li>Useful related topics
58 <ul>
59 <li>The <tt>-time-passes</tt> option
60 <li>How to use the LLVM Makefile system
61 <li>How to write a regression test
62 <li>
63 </ul>
64-->
65 </ul>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]66 <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]67 <ul>
68 <li><a href="#Value">The <tt>Value</tt> class</a>
69 <ul>
70 <li><a href="#User">The <tt>User</tt> class</a>
71 <ul>
72 <li><a href="#Instruction">The <tt>Instruction</tt> class</a>
73 <ul>
74 <li>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]75 </ul>
76 <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
77 <ul>
78 <li><a href="#BasicBlock">The <tt>BasicBlock</tt> class</a>
79 <li><a href="#Function">The <tt>Function</tt> class</a>
80 <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a>
81 </ul>
82 <li><a href="#Module">The <tt>Module</tt> class</a>
83 <li><a href="#Constant">The <tt>Constant</tt> class</a>
84 <ul>
85 <li>
86 <li>
87 </ul>
88 </ul>
89 <li><a href="#Type">The <tt>Type</tt> class</a>
90 <li><a href="#Argument">The <tt>Argument</tt> class</a>
91 </ul>
92 <li>The <tt>SymbolTable</tt> class
93 <li>The <tt>ilist</tt> and <tt>iplist</tt> classes
94 <ul>
95 <li>Creating, inserting, moving and deleting from LLVM lists
96 </ul>
97 <li>Important iterator invalidation semantics to be aware of
98 </ul>
99
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]100 <p><b>Written by <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>
Chris Lattnerf1ebdc32002-09-06 22:09:21 +0000[diff] [blame]101 <a href="mailto:sabre@nondot.org">Chris Lattner</a>, and
102 <a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b><p>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]103</ol>
104
105
106<!-- *********************************************************************** -->
107<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
108<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
109<a name="introduction">Introduction
110</b></font></td></tr></table><ul>
111<!-- *********************************************************************** -->
112
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]113This document is meant to highlight some of the important classes and interfaces
114available in the LLVM source-base. This manual is not intended to explain what
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]115LLVM is, how it works, and what LLVM code looks like. It assumes that you know
116the basics of LLVM and are interested in writing transformations or otherwise
117analyzing or manipulating the code.<p>
118
119This document should get you oriented so that you can find your way in the
120continuously growing source code that makes up the LLVM infrastructure. Note
121that this manual is not intended to serve as a replacement for reading the
122source code, so if you think there should be a method in one of these classes to
123do something, but it's not listed, check the source. Links to the <a
124href="/doxygen/">doxygen</a> sources are provided to make this as easy as
125possible.<p>
126
127The first section of this document describes general information that is useful
128to know when working in the LLVM infrastructure, and the second describes the
129Core LLVM classes. In the future this manual will be extended with information
130describing how to use extension libraries, such as dominator information, CFG
131traversal routines, and useful utilities like the <tt><a
132href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.<p>
133
134
135<!-- *********************************************************************** -->
136</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
137<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
138<a name="general">General Information
139</b></font></td></tr></table><ul>
140<!-- *********************************************************************** -->
141
142This section contains general information that is useful if you are working in
143the LLVM source-base, but that isn't specific to any particular API.<p>
144
145
146<!-- ======================================================================= -->
147</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
148<tr><td>&nbsp;</td><td width="100%">&nbsp;
149<font color="#EEEEFF" face="Georgia,Palatino"><b>
150<a name="stl">The C++ Standard Template Library</a>
151</b></font></td></tr></table><ul>
152
153LLVM makes heavy use of the C++ Standard Template Library (STL), perhaps much
154more than you are used to, or have seen before. Because of this, you might want
155to do a little background reading in the techniques used and capabilities of the
156library. There are many good pages that discuss the STL, and several books on
157the subject that you can get, so it will not be discussed in this document.<p>
158
159Here are some useful links:<p>
160<ol>
161<li><a href="http://www.dinkumware.com/htm_cpl/index.html">Dinkumware C++
162Library reference</a> - an excellent reference for the STL and other parts of
163the standard C++ library.<br>
164
165<li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
166Questions</a>
167
168<li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
169Contains a useful <a
170href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
171STL</a>.
172
173<li><a href="http://www.research.att.com/~bs/C++.html">Bjarne Stroustrup's C++
174Page</a>
175
176</ol><p>
177
178You are also encouraged to take a look at the <a
179href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
180to write maintainable code more than where to put your curly braces.<p>
181
182
Chris Lattner1d43fd42002-09-09 05:53:21 +0000[diff] [blame]183<!-- ======================================================================= -->
184</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
185<tr><td>&nbsp;</td><td width="100%">&nbsp;
186<font color="#EEEEFF" face="Georgia,Palatino"><b>
187<a name="isa">The isa&lt;&gt;, cast&lt;&gt; and dyn_cast&lt;&gt; templates</a>
188</b></font></td></tr></table><ul>
189
190
191
192
193
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]194
Chris Lattnerb99344f2002-09-06 16:40:10 +0000[diff] [blame]195<!-- *********************************************************************** -->
196</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
197<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
198<a name="common">Helpful Hints for Common Operations
199</b></font></td></tr></table><ul>
200<!-- *********************************************************************** -->
201
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]202This section describes how to perform some very simple transformations of LLVM
203code. This is meant to give examples of common idioms used, showing the
204practical side of LLVM transformations.<p>
205
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]206Because this is a "how-to" section, you should also read about the main classes
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]207that you will be working with. The <a href="#coreclasses">Core LLVM Class
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]208Hierarchy Reference</a> contains details and descriptions of the main classes
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]209that you should know about.<p>
210
211<!-- NOTE: this section should be heavy on example code -->
212
213
214<!-- ======================================================================= -->
215</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
216<tr><td>&nbsp;</td><td width="100%">&nbsp;
217<font color="#EEEEFF" face="Georgia,Palatino"><b>
218<a name="inspection">Basic Inspection and Traversal Routines</a>
219</b></font></td></tr></table><ul>
220
221
222<!-- LLVM has heirarchical representation: Module, Function, BasicBlock,
223Instruction. Common patterns for all levels. -->
224
225<!-- _______________________________________________________________________ -->
226</ul><h4><a name="iterate_function"><hr size=0>Iterating over the
227<tt>BasicBlock</tt>s in a <tt>Function</tt> </h4><ul>
228
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]229It's quite common to have a <tt>Function</tt> instance that you'd like
230to transform in some way; in particular, you'd like to manipulate its
231<tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over
232all of the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>.
233The following is an example that prints the name of a
234<tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s it
235contains:
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]236
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]237<pre>
238 // func is a pointer to a Function instance
239 for(Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {
240
241 // print out the name of the basic block if it has one, and then the
242 // number of instructions that it contains
243
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]244 cerr &lt;&lt "Basic block (name=" &lt;&lt i-&gt;getName() &lt;&lt; ") has "
245 &lt;&lt i-&gt;size() &lt;&lt " instructions.\n";
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]246 }
247</pre>
248
249Note that i can be used as if it were a pointer for the purposes of
250invoking member functions of the <tt>Instruction</tt> class. This is
251because the indirection operator is overloaded for the iterator
252classes. In the above code, the expression <tt>i->size()</tt> is
253exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]254
255<!-- _______________________________________________________________________ -->
256</ul><h4><a name="iterate_basicblock"><hr size=0>Iterating over the
257<tt>Instruction</tt>s in a <tt>BasicBlock</tt> </h4><ul>
258
Joel Stanleyaaeb1c12002-09-06 23:42:40 +0000[diff] [blame]259Just like when dealing with <tt>BasicBlock</tt>s in
260<tt>Function</tt>s, it's easy to iterate over the individual
261instructions that make up <tt>BasicBlock</tt>s. Here's a code snippet
262that prints out each instruction in a <tt>BasicBlock</tt>:
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]263
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]264<pre>
265 // blk is a pointer to a BasicBlock instance
Chris Lattner2b763062002-09-06 22:51:10 +0000[diff] [blame]266 for(BasicBlock::iterator i = blk-&gt;begin(), e = blk-&gt;end(); i != e; ++i) {
267 // the next statement works since operator&lt;&lt;(ostream&amp;,...)
268 // is overloaded for Instruction&amp;
Chris Lattner2b763062002-09-06 22:51:10 +0000[diff] [blame]269 cerr &lt;&lt; *i &lt;&lt; endl;
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]270</pre>
271
272However, this isn't really the best way to print out the contents of a
273<tt>BasicBlock</tt>! Since the ostream operators are overloaded for
274virtually anything you'll care about, you could have just invoked the
Chris Lattner2b763062002-09-06 22:51:10 +0000[diff] [blame]275print routine on the basic block itself: <tt>cerr &lt;&lt; *blk &lt;&lt;
276"\n";</tt>.<p>
277
278Note that currently operator&lt;&lt; is implemented for <tt>Value*</tt>, so it
279will print out the contents of the pointer, instead of
280the pointer value you might expect. This is a deprecated interface that will
281be removed in the future, so it's best not to depend on it. To print out the
282pointer value for now, you must cast to <tt>void*</tt>.<p>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]283
284<!-- _______________________________________________________________________ -->
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]285</ul><h4><a name="iterate_institer"><hr size=0>Iterating over the
286<tt>Instruction</tt>s in a <tt>Function</tt></h4><ul>
287
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]288If you're finding that you commonly iterate over a <tt>Function</tt>'s
289<tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s
290<tt>Instruction</tt>s, <tt>InstIterator</tt> should be used instead.
291You'll need to include <tt>llvm/Support/InstIterator.h</tt>, and then
292instantiate <tt>InstIterator</tt>s explicitly in your code. Here's a
293small example that shows how to dump all instructions in a function to
294stderr (<b>Note:</b> Dereferencing an <tt>InstIterator</tt> yields an
295<tt>Instruction*</tt>, <i>not</i> an <tt>Instruction&amp</tt>!):
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]296
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]297<pre>
298#include "llvm/Support/InstIterator.h"
299...
300// Suppose F is a ptr to a function
301for(inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
302 cerr &lt;&lt **i &lt;&lt "\n";
303</pre>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]304
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]305Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
306worklist with its initial contents. For example, if you wanted to
307initialize a worklist to contain all instructions in a
308<tt>Function</tt> F, all you would need to do is something like:
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]309
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]310<pre>
311std::set&lt;Instruction*&gt worklist;
312worklist.insert(inst_begin(F), inst_end(F));
313</pre>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]314
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]315The STL set <tt>worklist</tt> would now contain all instructions in
316the <tt>Function</tt> pointed to by F.
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]317
318<!-- _______________________________________________________________________ -->
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]319</ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]320pointer (and vice-versa) </h4><ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]321
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]322Sometimes, it'll be useful to grab a reference (or pointer) to a class
323instance when all you've got at hand is an iterator. Well, extracting
324a reference or a pointer from an iterator is very straightforward.
325Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
326<tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
327
328<pre>
Chris Lattner83b5ee02002-09-06 22:12:58 +0000[diff] [blame]329 Instruction&amp; inst = *i; // grab reference to instruction reference
330 Instruction* pinst = &amp;*i; // grab pointer to instruction reference
331 const Instruction&amp; inst = *j;
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]332</pre>
333However, the iterators you'll be working with in the LLVM framework
334are special: they will automatically convert to a ptr-to-instance type
335whenever they need to. Instead of dereferencing the iterator and then
336taking the address of the result, you can simply assign the iterator
337to the proper pointer type and you get the dereference and address-of
338operation as a result of the assignment (behind the scenes, this is a
339result of overloading casting mechanisms). Thus the last line of the
340last example,
341
Chris Lattner83b5ee02002-09-06 22:12:58 +0000[diff] [blame]342<pre>Instruction* pinst = &amp;*i;</pre>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]343
344is semantically equivalent to
345
346<pre>Instruction* pinst = i;</pre>
347
348<b>Caveat emptor</b>: The above syntax works <i>only</i> when you're
349<i>not</i> working with <tt>dyn_cast</tt>. The template definition of
350<tt>dyn_cast</tt> isn't implemented to handle this yet, so you'll
351still need the following in order for things to work properly:
352
353<pre>
354BasicBlock::iterator bbi = ...;
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]355BranchInst* b = dyn_cast&lt;BranchInst&gt;(&amp*bbi);
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]356</pre>
357
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]358It's also possible to turn a class pointer into the corresponding
359iterator. Usually, this conversion is quite inexpensive. The
360following code snippet illustrates use of the conversion constructors
361provided by LLVM iterators. By using these, you can explicitly grab
362the iterator of something without actually obtaining it via iteration
363over some structure:
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]364
365<pre>
366void printNextInstruction(Instruction* inst) {
367 BasicBlock::iterator it(inst);
368 ++it; // after this line, it refers to the instruction after *inst.
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]369 if(it != inst-&gt;getParent()->end()) cerr &lt;&lt *it &lt;&lt endl;
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]370}
371</pre>
Joel Stanleyaaeb1c12002-09-06 23:42:40 +0000[diff] [blame]372Of course, this example is strictly pedagogical, because it'd be much
373better to explicitly grab the next instruction directly from inst.
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]374
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]375<!-- dereferenced iterator = Class &
376 iterators have converting constructor for 'Class *'
377 iterators automatically convert to 'Class *' except in dyn_cast<> case
378 -->
379
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]380<!--_______________________________________________________________________-->
381</ul><h4><a name="iterate_complex"><hr size=0>Finding call sites: a slightly
382more complex example </h4><ul>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]383
384Say that you're writing a FunctionPass and would like to count all the
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]385locations in the entire module (that is, across every
386<tt>Function</tt>) where a certain function (i.e. <tt>Function</tt>*)
387passed into the FunctionPass constructor. As you'll learn later, you
388may want to use an <tt>InstVisitor</tt> to accomplish this in a much
389more straightforward manner, but this example will allow us to explore
390how you'd do it if you didn't have <tt>InstVisitor</tt> around. In
391pseudocode, this is what we want to do:
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]392
393<pre>
394initialize callCounter to zero
395for each Function f in the Module
396 for each BasicBlock b in f
397 for each Instruction i in b
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]398 if(i is a CallInst and calls the given function)
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]399 increment callCounter
400</pre>
401
402And the actual code is (remember, since we're writing a
403<tt>FunctionPass</tt> our <tt>FunctionPass</tt>-derived class simply
404has to override the <tt>runOnFunction</tt> method...):
405
406<pre>
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]407class OurFunctionPass : public FunctionPass {
408 public:
409 OurFunctionPass(Function* func): m_func(func) { }
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]410
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]411 virtual doInitialization(Module&amp M) { callCounter = 0; };
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]412
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]413 virtual runOnFunction(Function&amp F) {
414 for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
415 for(BasicBlock::iterator i = b-&gt;begin(); ie = b-&gt;end(); i != ie; ++i) {
416 if(CallInst* callInst = dyn_cast<CallInst>(&amp;*inst)) {
417 // we know we've encountered a call instruction, so we
418 // need to determine if it's a call to the
419 // function pointed to by m_func or not.
420
421 if(callInst-&gt;getCalledFunction() == m_func)
422 ++callCounter;
423 }
424 }
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]425 }
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]426
427 private:
428 Function* m_func; // we're counting calls to this function.
429 static unsigned callCounter;
430};
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]431</pre>
432
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]433<!--_______________________________________________________________________-->
434</ul><h4><a name="iterate_chains"><hr size=0>Iterating over def-use &amp;
435use-def chains</h4><ul>
436
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]437<!--
438 def-use chains ("finding all users of"): Value::use_begin/use_end
439 use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
440-->
441
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]442<!-- ======================================================================= -->
443</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
444<tr><td>&nbsp;</td><td width="100%">&nbsp;
445<font color="#EEEEFF" face="Georgia,Palatino"><b>
446<a name="simplechanges">Making simple changes</a>
447</b></font></td></tr></table><ul>
448
449<!-- Value::replaceAllUsesWith
450 User::replaceUsesOfWith
451 Point out: include/llvm/Transforms/Utils/
452 especially BasicBlockUtils.h with:
453 ReplaceInstWithValue, ReplaceInstWithInst
454
455-->
Chris Lattnerb99344f2002-09-06 16:40:10 +0000[diff] [blame]456
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]457
458<!-- *********************************************************************** -->
459</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
460<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]461<a name="coreclasses">The Core LLVM Class Hierarchy Reference
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]462</b></font></td></tr></table><ul>
463<!-- *********************************************************************** -->
464
465The Core LLVM classes are the primary means of representing the program being
466inspected or transformed. The core LLVM classes are defined in header files in
467the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
468directory.<p>
469
470
471<!-- ======================================================================= -->
472</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
473<tr><td>&nbsp;</td><td width="100%">&nbsp;
474<font color="#EEEEFF" face="Georgia,Palatino"><b>
475<a name="Value">The <tt>Value</tt> class</a>
476</b></font></td></tr></table><ul>
477
478<tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
479doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
480
481
482The <tt>Value</tt> class is the most important class in LLVM Source base. It
483represents a typed value that may be used (among other things) as an operand to
484an instruction. There are many different types of <tt>Value</tt>s, such as <a
485href="#Constant"><tt>Constant</tt></a>s, <a
486href="#Argument"><tt>Argument</tt></a>s, and even <a
487href="#Instruction"><tt>Instruction</tt></a>s and <a
488href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
489
490A particular <tt>Value</tt> may be used many times in the LLVM representation
491for a program. For example, an incoming argument to a function (represented
492with an instance of the <a href="#Argument">Argument</a> class) is "used" by
493every instruction in the function that references the argument. To keep track
494of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
495href="#User"><tt>User</tt></a>s that is using it (the <a
496href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
497graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]498def-use information in the program, and is accessible through the <tt>use_</tt>*
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]499methods, shown below.<p>
500
501Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
502this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
503method. <a name="#nameWarning">In addition, all LLVM values can be named. The
504"name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
505
506<pre>
507 %<b>foo</b> = add int 1, 2
508</pre>
509
510The name of this instruction is "foo". <b>NOTE</b> that the name of any value
511may be missing (an empty string), so names should <b>ONLY</b> be used for
512debugging (making the source code easier to read, debugging printouts), they
513should not be used to keep track of values or map between them. For this
514purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
515instead.<p>
516
517One important aspect of LLVM is that there is no distinction between an SSA
518variable and the operation that produces it. Because of this, any reference to
519the value produced by an instruction (or the value available as an incoming
520argument, for example) is represented as a direct pointer to the class that
521represents this value. Although this may take some getting used to, it
522simplifies the representation and makes it easier to manipulate.<p>
523
524
525<!-- _______________________________________________________________________ -->
526</ul><h4><a name="m_Value"><hr size=0>Important Public Members of
527the <tt>Value</tt> class</h4><ul>
528
529<li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
530 <tt>Value::use_const_iterator</tt>
531 - Typedef for const_iterator over the use-list<br>
532 <tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
533 <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
534 <tt>use_iterator use_begin()</tt>
535 - Get an iterator to the start of the use-list.<br>
536 <tt>use_iterator use_end()</tt>
537 - Get an iterator to the end of the use-list.<br>
538 <tt><a href="#User">User</a> *use_back()</tt>
539 - Returns the last element in the list.<p>
540
541These 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>
542
543<li><tt><a href="#Type">Type</a> *getType() const</tt><p>
544This method returns the Type of the Value.
545
546<li><tt>bool hasName() const</tt><br>
547 <tt>std::string getName() const</tt><br>
548 <tt>void setName(const std::string &amp;Name)</tt><p>
549
550This family of methods is used to access and assign a name to a <tt>Value</tt>,
551be aware of the <a href="#nameWarning">precaution above</a>.<p>
552
553
554<li><tt>void replaceAllUsesWith(Value *V)</tt><p>
555
556This method traverses the use list of a <tt>Value</tt> changing all <a
557href="#User"><tt>User</tt>'s</a> of the current value to refer to "<tt>V</tt>"
558instead. For example, if you detect that an instruction always produces a
559constant value (for example through constant folding), you can replace all uses
560of the instruction with the constant like this:<p>
561
562<pre>
563 Inst-&gt;replaceAllUsesWith(ConstVal);
564</pre><p>
565
566
567
568<!-- ======================================================================= -->
569</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
570<tr><td>&nbsp;</td><td width="100%">&nbsp;
571<font color="#EEEEFF" face="Georgia,Palatino"><b>
572<a name="User">The <tt>User</tt> class</a>
573</b></font></td></tr></table><ul>
574
575<tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
576doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
577Superclass: <a href="#Value"><tt>Value</tt></a><p>
578
579
580The <tt>User</tt> class is the common base class of all LLVM nodes that may
581refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
582that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
583referring to. The <tt>User</tt> class itself is a subclass of
584<tt>Value</tt>.<p>
585
586The operands of a <tt>User</tt> point directly to the LLVM <a
587href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
588Single Assignment (SSA) form, there can only be one definition referred to,
589allowing this direct connection. This connection provides the use-def
590information in LLVM.<p>
591
592<!-- _______________________________________________________________________ -->
593</ul><h4><a name="m_User"><hr size=0>Important Public Members of
594the <tt>User</tt> class</h4><ul>
595
596The <tt>User</tt> class exposes the operand list in two ways: through an index
597access interface and through an iterator based interface.<p>
598
599<li><tt>Value *getOperand(unsigned i)</tt><br>
600 <tt>unsigned getNumOperands()</tt><p>
601
602These two methods expose the operands of the <tt>User</tt> in a convenient form
603for direct access.<p>
604
605<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
606 <tt>User::op_const_iterator</tt>
607 <tt>use_iterator op_begin()</tt>
608 - Get an iterator to the start of the operand list.<br>
609 <tt>use_iterator op_end()</tt>
610 - Get an iterator to the end of the operand list.<p>
611
612Together, these methods make up the iterator based interface to the operands of
613a <tt>User</tt>.<p>
614
615
616
617<!-- ======================================================================= -->
618</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
619<tr><td>&nbsp;</td><td width="100%">&nbsp;
620<font color="#EEEEFF" face="Georgia,Palatino"><b>
621<a name="Instruction">The <tt>Instruction</tt> class</a>
622</b></font></td></tr></table><ul>
623
624<tt>#include "<a
625href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
626doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
627Superclasses: <a href="#User"><tt>User</tt></a>, <a
628href="#Value"><tt>Value</tt></a><p>
629
630The <tt>Instruction</tt> class is the common base class for all LLVM
631instructions. It provides only a few methods, but is a very commonly used
632class. The primary data tracked by the <tt>Instruction</tt> class itself is the
633opcode (instruction type) and the parent <a
634href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
635into. To represent a specific type of instruction, one of many subclasses of
636<tt>Instruction</tt> are used.<p>
637
638Because the <tt>Instruction</tt> class subclasses the <a
639href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
640way as for other <a href="#User"><tt>User</tt></a>s (with the
641<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
642<tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
643
644
645<!-- _______________________________________________________________________ -->
646</ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
647the <tt>Instruction</tt> class</h4><ul>
648
649<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
650
651Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
652<tt>Instruction</tt> is embedded into.<p>
653
654<li><tt>bool hasSideEffects()</tt><p>
655
656Returns true if the instruction has side effects, i.e. it is a <tt>call</tt>,
657<tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
658
659<li><tt>unsigned getOpcode()</tt><p>
660
661Returns the opcode for the <tt>Instruction</tt>.<p>
662
663<!--
664
665\subsection{Subclasses of Instruction :}
666\begin{itemize}
667<li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
668 \begin{itemize}
669 <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.
670 \end{itemize}
671<li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
672 \begin{itemize}
673 <li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
674 <li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
675 <li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
676 \end{itemize}
677
678<li>PHINode : This represents the PHI instructions in the SSA form.
679 \begin{itemize}
680 <li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
681 <li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
682 <li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
683 <li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
684 <li><tt> void addIncoming(Value *D, BasicBlock *BB)</tt>:
685 Add an incoming value to the end of the PHI list
686 <li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
687 Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
688 \end{itemize}
689<li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
690<li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
691 \begin{itemize}
692 <li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
693 \end{itemize}
694<li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
695 \begin{itemize}
696 <li><tt>Value * getPointerOperand ()</tt>: Returns the Pointer Operand which is typically the 0th operand.
697 \end{itemize}
698<li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
699 \begin{itemize}
700 <li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
701 <li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
702 <li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
703 \end{itemize}
704
705\end{itemize}
706
707-->
708
709
710<!-- ======================================================================= -->
711</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
712<tr><td>&nbsp;</td><td width="100%">&nbsp;
713<font color="#EEEEFF" face="Georgia,Palatino"><b>
714<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
715</b></font></td></tr></table><ul>
716
717<tt>#include "<a
718href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
719doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
720Superclass: <a href="#Value"><tt>Value</tt></a><p>
721
722
723This class represents a single entry multiple exit section of the code, commonly
724known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
725maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
726the body of the block. Matching the language definition, the last element of
727this list of instructions is always a terminator instruction (a subclass of the
728<a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
729
730In addition to tracking the list of instructions that make up the block, the
731<tt>BasicBlock</tt> class also keeps track of the <a
732href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
733
734Note that <tt>BasicBlock</tt>s themselves are <a
735href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
736like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
737<tt>label</tt>.<p>
738
739
740<!-- _______________________________________________________________________ -->
741</ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
742the <tt>BasicBlock</tt> class</h4><ul>
743
744<li><tt>BasicBlock(const std::string &amp;Name = "", <a
745href="#Function">Function</a> *Parent = 0)</tt><p>
746
747The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
748insertion into a function. The constructor simply takes a name for the new
749block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
750into. If the <tt>Parent</tt> parameter is specified, the new
751<tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
752href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
753manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
754
755<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
756 <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
757 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
758 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
759
760These methods and typedefs are forwarding functions that have the same semantics
761as the standard library methods of the same names. These methods expose the
762underlying instruction list of a basic block in a way that is easy to
763manipulate. To get the full complement of container operations (including
764operations to update the list), you must use the <tt>getInstList()</tt>
765method.<p>
766
767<li><tt>BasicBlock::InstListType &amp;getInstList()</tt><p>
768
769This method is used to get access to the underlying container that actually
770holds the Instructions. This method must be used when there isn't a forwarding
771function in the <tt>BasicBlock</tt> class for the operation that you would like
772to perform. Because there are no forwarding functions for "updating"
773operations, you need to use this if you want to update the contents of a
774<tt>BasicBlock</tt>.<p>
775
776<li><tt><A href="#Function">Function</a> *getParent()</tt><p>
777
778Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
779embedded into, or a null pointer if it is homeless.<p>
780
781<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
782
783Returns a pointer to the terminator instruction that appears at the end of the
784<tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
785instruction in the block is not a terminator, then a null pointer is
786returned.<p>
787
788
789<!-- ======================================================================= -->
790</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
791<tr><td>&nbsp;</td><td width="100%">&nbsp;
792<font color="#EEEEFF" face="Georgia,Palatino"><b>
793<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
794</b></font></td></tr></table><ul>
795
796<tt>#include "<a
797href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
798doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
799Superclasses: <a href="#User"><tt>User</tt></a>, <a
800href="#Value"><tt>Value</tt></a><p>
801
802Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
803href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
804visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
805Because they are visible at global scope, they are also subject to linking with
806other globals defined in different translation units. To control the linking
807process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
808<tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
809
810If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
811<tt>static</tt> in C), it is not visible to code outside the current translation
812unit, and does not participate in linking. If it has external linkage, it is
813visible to external code, and does participate in linking. In addition to
814linkage information, <tt>GlobalValue</tt>s keep track of which <a
815href="#Module"><tt>Module</tt></a> they are currently part of.<p>
816
817Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
818their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
819always a pointer to its contents. This is explained in the LLVM Language
820Reference Manual.<p>
821
822
823<!-- _______________________________________________________________________ -->
824</ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
825the <tt>GlobalValue</tt> class</h4><ul>
826
827<li><tt>bool hasInternalLinkage() const</tt><br>
828 <tt>bool hasExternalLinkage() const</tt><br>
829 <tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
830
831These methods manipulate the linkage characteristics of the
832<tt>GlobalValue</tt>.<p>
833
834<li><tt><a href="#Module">Module</a> *getParent()</tt><p>
835
836This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
837currently embedded into.<p>
838
839
840
841<!-- ======================================================================= -->
842</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
843<tr><td>&nbsp;</td><td width="100%">&nbsp;
844<font color="#EEEEFF" face="Georgia,Palatino"><b>
845<a name="Function">The <tt>Function</tt> class</a>
846</b></font></td></tr></table><ul>
847
848<tt>#include "<a
849href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
850doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
851Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
852href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
853
854The <tt>Function</tt> class represents a single procedure in LLVM. It is
855actually one of the more complex classes in the LLVM heirarchy because it must
856keep track of a large amount of data. The <tt>Function</tt> class keeps track
857of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
858href="#Argument"><tt>Argument</tt></a>s, and a <a
859href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
860
861The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
862used part of <tt>Function</tt> objects. The list imposes an implicit ordering
863of the blocks in the function, which indicate how the code will be layed out by
864the backend. Additionally, the first <a
865href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
866<tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
867block. There are no implicit exit nodes, and in fact there may be multiple exit
868nodes from a single <tt>Function</tt>. If the <a
869href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
870the <tt>Function</tt> is actually a function declaration: the actual body of the
871function hasn't been linked in yet.<p>
872
873In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
874<tt>Function</tt> class also keeps track of the list of formal <a
875href="#Argument"><tt>Argument</tt></a>s that the function receives. This
876container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
877nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
878the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
879
880The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
881feature that is only used when you have to look up a value by name. Aside from
882that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
883make sure that there are not conflicts between the names of <a
884href="#Instruction"><tt>Instruction</tt></a>s, <a
885href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
886href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
887
888
889<!-- _______________________________________________________________________ -->
890</ul><h4><a name="m_Function"><hr size=0>Important Public Members of
891the <tt>Function</tt> class</h4><ul>
892
893<li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &amp;N = "")</tt><p>
894
895Constructor used when you need to create new <tt>Function</tt>s to add the the
896program. The constructor must specify the type of the function to create and
897whether or not it should start out with internal or external linkage.<p>
898
899<li><tt>bool isExternal()</tt><p>
900
901Return whether or not the <tt>Function</tt> has a body defined. If the function
902is "external", it does not have a body, and thus must be resolved by linking
903with a function defined in a different translation unit.<p>
904
905
906<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
907 <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
908 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
909 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
910
911These are forwarding methods that make it easy to access the contents of a
912<tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
913list.<p>
914
915<li><tt>Function::BasicBlockListType &amp;getBasicBlockList()</tt><p>
916
917Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
918neccesary to use when you need to update the list or perform a complex action
919that doesn't have a forwarding method.<p>
920
921
922<li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
923 <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
924 <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
925 <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
926
927These are forwarding methods that make it easy to access the contents of a
928<tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
929
930<li><tt>Function::ArgumentListType &amp;getArgumentList()</tt><p>
931
932Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
933neccesary to use when you need to update the list or perform a complex action
934that doesn't have a forwarding method.<p>
935
936
937
938<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
939
940Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
941function. Because the entry block for the function is always the first block,
942this returns the first block of the <tt>Function</tt>.<p>
943
944<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
945 <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
946
947This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
948and returns the return type of the function, or the <a
949href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
950
951
952<li><tt>bool hasSymbolTable() const</tt><p>
953
954Return true if the <tt>Function</tt> has a symbol table allocated to it and if
955there is at least one entry in it.<p>
956
957<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
958
959Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
960<tt>Function</tt> or a null pointer if one has not been allocated (because there
961are no named values in the function).<p>
962
963<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
964
965Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
966<tt>Function</tt> or allocate a new <a
967href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
968should only be used when adding elements to the <a
969href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
970not left laying around.<p>
971
972
973
974<!-- ======================================================================= -->
975</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
976<tr><td>&nbsp;</td><td width="100%">&nbsp;
977<font color="#EEEEFF" face="Georgia,Palatino"><b>
978<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
979</b></font></td></tr></table><ul>
980
981<tt>#include "<a
982href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
983doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
984Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
985href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
986
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]987Global variables are represented with the (suprise suprise)
988<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
989also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
990are always referenced by their address (global values must live in memory, so
991their "name" refers to their address). Global variables may have an initial
992value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
993have an initializer, they may be marked as "constant" themselves (indicating
994that their contents never change at runtime).<p>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]995
996
997<!-- _______________________________________________________________________ -->
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]998</ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
999<tt>GlobalVariable</tt> class</h4><ul>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1000
1001<li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
1002isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
1003&amp;Name = "")</tt><p>
1004
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1005Create a new global variable of the specified type. If <tt>isConstant</tt> is
1006true then the global variable will be marked as unchanging for the program, and
1007if <tt>isInternal</tt> is true the resultant global variable will have internal
1008linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
1009
1010
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1011<li><tt>bool isConstant() const</tt><p>
1012
1013Returns true if this is a global variable is known not to be modified at
1014runtime.<p>
1015
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1016
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1017<li><tt>bool hasInitializer()</tt><p>
1018
1019Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
1020
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1021
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1022<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
1023
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1024Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
1025this method if there is no initializer.<p>
1026
1027
1028<!-- ======================================================================= -->
1029</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1030<tr><td>&nbsp;</td><td width="100%">&nbsp;
1031<font color="#EEEEFF" face="Georgia,Palatino"><b>
1032<a name="Module">The <tt>Module</tt> class</a>
1033</b></font></td></tr></table><ul>
1034
1035<tt>#include "<a
1036href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
1037doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
1038
1039The <tt>Module</tt> class represents the top level structure present in LLVM
1040programs. An LLVM module is effectively either a translation unit of the
1041original program or a combination of several translation units merged by the
1042linker. The <tt>Module</tt> class keeps track of a list of <a
1043href="#Function"><tt>Function</tt></a>s, a list of <a
1044href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
1045href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
1046helpful member functions that try to make common operations easy.<p>
1047
1048
1049<!-- _______________________________________________________________________ -->
1050</ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
1051<tt>Module</tt> class</h4><ul>
1052
1053<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
1054 <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
1055 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1056 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1057
1058These are forwarding methods that make it easy to access the contents of a
1059<tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
1060list.<p>
1061
1062<li><tt>Module::FunctionListType &amp;getFunctionList()</tt><p>
1063
1064Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
1065neccesary to use when you need to update the list or perform a complex action
1066that doesn't have a forwarding method.<p>
1067
1068<!-- Global Variable -->
1069<hr size=0>
1070
1071<li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
1072 <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
1073 <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
1074 <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
1075
1076These are forwarding methods that make it easy to access the contents of a
1077<tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
1078list.<p>
1079
1080<li><tt>Module::GlobalListType &amp;getGlobalList()</tt><p>
1081
1082Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
1083This is neccesary to use when you need to update the list or perform a complex
1084action that doesn't have a forwarding method.<p>
1085
1086
1087<!-- Symbol table stuff -->
1088<hr size=0>
1089
1090<li><tt>bool hasSymbolTable() const</tt><p>
1091
1092Return true if the <tt>Module</tt> has a symbol table allocated to it and if
1093there is at least one entry in it.<p>
1094
1095<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1096
1097Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1098<tt>Module</tt> or a null pointer if one has not been allocated (because there
1099are no named values in the function).<p>
1100
1101<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
1102
1103Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1104<tt>Module</tt> or allocate a new <a
1105href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
1106should only be used when adding elements to the <a
1107href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
1108not left laying around.<p>
1109
1110
1111<!-- Convenience methods -->
1112<hr size=0>
1113
1114<li><tt><a href="#Function">Function</a> *getFunction(const std::string &amp;Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt><p>
1115
1116Look up the specified function in the <tt>Module</tt> <a
1117href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
1118<tt>null</tt>.<p>
1119
1120
1121<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
1122 &amp;Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
1123
1124Look up the specified function in the <tt>Module</tt> <a
1125href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
1126external declaration for the function and return it.<p>
1127
1128
1129<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
1130
1131If there is at least one entry in the <a
1132href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
1133href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
1134string.<p>
1135
1136
1137<li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
1138*Ty)</tt><p>
1139
1140Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
1141<tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
1142is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
1143modified.<p>
1144
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1145
1146<!-- ======================================================================= -->
1147</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1148<tr><td>&nbsp;</td><td width="100%">&nbsp;
1149<font color="#EEEEFF" face="Georgia,Palatino"><b>
1150<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
1151</b></font></td></tr></table><ul>
1152
1153Constant represents a base class for different types of constants. It is
1154subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
1155ConstantArray etc for representing the various types of Constants.<p>
1156
1157
1158<!-- _______________________________________________________________________ -->
1159</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1160
1161<li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
1162
1163
1164
1165
1166\subsection{Important Subclasses of Constant}
1167\begin{itemize}
1168<li>ConstantSInt : This subclass of Constant represents a signed integer constant.
1169 \begin{itemize}
1170 <li><tt>int64_t getValue () const</tt>: Returns the underlying value of this constant.
1171 \end{itemize}
1172<li>ConstantUInt : This class represents an unsigned integer.
1173 \begin{itemize}
1174 <li><tt>uint64_t getValue () const</tt>: Returns the underlying value of this constant.
1175 \end{itemize}
1176<li>ConstantFP : This class represents a floating point constant.
1177 \begin{itemize}
1178 <li><tt>double getValue () const</tt>: Returns the underlying value of this constant.
1179 \end{itemize}
1180<li>ConstantBool : This represents a boolean constant.
1181 \begin{itemize}
1182 <li><tt>bool getValue () const</tt>: Returns the underlying value of this constant.
1183 \end{itemize}
1184<li>ConstantArray : This represents a constant array.
1185 \begin{itemize}
1186 <li><tt>const std::vector<Use> &amp;getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1187 \end{itemize}
1188<li>ConstantStruct : This represents a constant struct.
1189 \begin{itemize}
1190 <li><tt>const std::vector<Use> &amp;getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1191 \end{itemize}
1192<li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
1193 \begin{itemize}
1194<li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
1195 \end{itemize}
1196\end{itemize}
1197
1198
1199<!-- ======================================================================= -->
1200</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1201<tr><td>&nbsp;</td><td width="100%">&nbsp;
1202<font color="#EEEEFF" face="Georgia,Palatino"><b>
1203<a name="Type">The <tt>Type</tt> class and Derived Types</a>
1204</b></font></td></tr></table><ul>
1205
1206Type as noted earlier is also a subclass of a Value class. Any primitive
1207type (like int, short etc) in LLVM is an instance of Type Class. All
1208other types are instances of subclasses of type like FunctionType,
1209ArrayType etc. DerivedType is the interface for all such dervied types
1210including FunctionType, ArrayType, PointerType, StructType. Types can have
1211names. They can be recursive (StructType). There exists exactly one instance
1212of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
1213
1214<!-- _______________________________________________________________________ -->
1215</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1216
1217<li><tt>PrimitiveID getPrimitiveID () const</tt>: Returns the base type of the type.
1218<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.
1219<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.
1220<li><tt> bool isInteger () const</tt>: Equilivent to isSigned() || isUnsigned(), but with only a single virtual function invocation.
1221<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.
1222
1223<li><tt>bool isFloatingPoint ()</tt>: Return true if this is one of the two floating point types.
1224<li><tt>bool isRecursive () const</tt>: Returns rue if the type graph contains a cycle.
1225<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.
1226<li><tt>bool isPrimitiveType () const</tt>: Returns true if it is a primitive type.
1227<li><tt>bool isDerivedType () const</tt>: Returns true if it is a derived type.
1228<li><tt>const Type * getContainedType (unsigned i) const</tt>:
1229This 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.
1230<li><tt>unsigned getNumContainedTypes () const</tt>: Return the number of types in the derived type.
1231
1232
1233
1234\subsection{Derived Types}
1235\begin{itemize}
1236<li>SequentialType : This is subclassed by ArrayType and PointerType
1237 \begin{itemize}
1238 <li><tt>const Type * getElementType () const</tt>: Returns the type of each of the elements in the sequential type.
1239 \end{itemize}
1240<li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
1241 \begin{itemize}
1242 <li><tt>unsigned getNumElements () const</tt>: Returns the number of elements in the array.
1243 \end{itemize}
1244<li>PointerType : Subclass of SequentialType for pointer types.
1245<li>StructType : subclass of DerivedTypes for struct types
1246<li>FunctionType : subclass of DerivedTypes for function types.
1247 \begin{itemize}
1248
1249 <li><tt>bool isVarArg () const</tt>: Returns true if its a vararg function
1250 <li><tt> const Type * getReturnType () const</tt>: Returns the return type of the function.
1251 <li><tt> const ParamTypes &amp;getParamTypes () const</tt>: Returns a vector of parameter types.
1252 <li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
1253 <li><tt> const unsigned getNumParams () const</tt>: Returns the number of formal parameters.
1254 \end{itemize}
1255\end{itemize}
1256
1257
1258
1259
1260<!-- ======================================================================= -->
1261</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1262<tr><td>&nbsp;</td><td width="100%">&nbsp;
1263<font color="#EEEEFF" face="Georgia,Palatino"><b>
1264<a name="Argument">The <tt>Argument</tt> class</a>
1265</b></font></td></tr></table><ul>
1266
1267This subclass of Value defines the interface for incoming formal arguments to a
1268function. A Function maitanis a list of its formal arguments. An argument has a
1269pointer to the parent Function.
1270
1271
1272
1273
1274<!-- *********************************************************************** -->
1275</ul>
1276<!-- *********************************************************************** -->
1277
1278<hr><font size-1>
1279<address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
1280<a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1281<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
1282<!-- hhmts start -->
Joel Stanleye7be6502002-09-09 15:50:33 +0000[diff] [blame^]1283Last modified: Mon Sep 9 10:47:48 CDT 2002
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1284<!-- hhmts end -->
1285</font></body></html>