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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
288<!-- Using llvm/Support/InstIterator.h to directly get at the instructions in a
289function.
290
291Warning: *I returns an Instruction*, not an Instruction&
292
293 -->
294
295
296
297<!-- _______________________________________________________________________ -->
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]298</ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
299pointer </h4><ul>
300
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]301Sometimes, it'll be useful to grab a reference (or pointer) to a class
302instance when all you've got at hand is an iterator. Well, extracting
303a reference or a pointer from an iterator is very straightforward.
304Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
305<tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
306
307<pre>
Chris Lattner83b5ee02002-09-06 22:12:58 +0000[diff] [blame]308 Instruction&amp; inst = *i; // grab reference to instruction reference
309 Instruction* pinst = &amp;*i; // grab pointer to instruction reference
310 const Instruction&amp; inst = *j;
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]311</pre>
312However, the iterators you'll be working with in the LLVM framework
313are special: they will automatically convert to a ptr-to-instance type
314whenever they need to. Instead of dereferencing the iterator and then
315taking the address of the result, you can simply assign the iterator
316to the proper pointer type and you get the dereference and address-of
317operation as a result of the assignment (behind the scenes, this is a
318result of overloading casting mechanisms). Thus the last line of the
319last example,
320
Chris Lattner83b5ee02002-09-06 22:12:58 +0000[diff] [blame]321<pre>Instruction* pinst = &amp;*i;</pre>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]322
323is semantically equivalent to
324
325<pre>Instruction* pinst = i;</pre>
326
327<b>Caveat emptor</b>: The above syntax works <i>only</i> when you're
328<i>not</i> working with <tt>dyn_cast</tt>. The template definition of
329<tt>dyn_cast</tt> isn't implemented to handle this yet, so you'll
330still need the following in order for things to work properly:
331
332<pre>
333BasicBlock::iterator bbi = ...;
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]334BranchInst* b = dyn_cast&lt;BranchInst&gt;(&amp*bbi);
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]335</pre>
336
337The following code snippet illustrates use of the conversion
338constructors provided by LLVM iterators. By using these, you can
339explicitly grab the iterator of something without actually obtaining
340it via iteration over some structure:
341
342<pre>
343void printNextInstruction(Instruction* inst) {
344 BasicBlock::iterator it(inst);
345 ++it; // after this line, it refers to the instruction after *inst.
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]346 if(it != inst-&gt;getParent()->end()) cerr &lt;&lt *it &lt;&lt endl;
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]347}
348</pre>
Joel Stanleyaaeb1c12002-09-06 23:42:40 +0000[diff] [blame]349Of course, this example is strictly pedagogical, because it'd be much
350better to explicitly grab the next instruction directly from inst.
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]351
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]352<!-- dereferenced iterator = Class &
353 iterators have converting constructor for 'Class *'
354 iterators automatically convert to 'Class *' except in dyn_cast<> case
355 -->
356
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]357<!--_______________________________________________________________________-->
358</ul><h4><a name="iterate_complex"><hr size=0>Finding call sites: a slightly
359more complex example </h4><ul>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]360
361Say that you're writing a FunctionPass and would like to count all the
362locations in the entire module (that is, across every <tt>Function</tt>)
363where a certain function named foo (that takes an int and returns an
364int) is called. As you'll learn later, you may want to use an
365<tt>InstVisitor</tt> to accomplish this in a much more straightforward
366manner, but this example will allow us to explore how you'd do it if
367you didn't have <tt>InstVisitor</tt> around. In pseudocode, this is
368what we want to do:
369
370<pre>
371initialize callCounter to zero
372for each Function f in the Module
373 for each BasicBlock b in f
374 for each Instruction i in b
375 if(i is a CallInst and foo is the function it calls)
376 increment callCounter
377</pre>
378
379And the actual code is (remember, since we're writing a
380<tt>FunctionPass</tt> our <tt>FunctionPass</tt>-derived class simply
381has to override the <tt>runOnFunction</tt> method...):
382
383<pre>
384
385// Assume callCounter is a private member of the pass class being written,
386// and has been initialized in the pass class constructor.
387
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]388virtual runOnFunction(Function&amp F) {
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]389
390 // Remember, we assumed that the signature of foo was "int foo(int)";
391 // the first thing we'll do is grab the pointer to that function (as a
392 // Function*) so we can use it later when we're examining the
393 // parameters of a CallInst. All of the code before the call to
394 // Module::getOrInsertFunction() is in preparation to do symbol-table
395 // to find the function pointer.
396
397 vector<const Type*> params;
398 params.push_back(Type::IntTy);
399 const FunctionType* fooType = FunctionType::get(Type::IntTy, params);
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]400 Function* foo = F.getParent()-&gt;getOrInsertFunction("foo", fooType);
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]401
402 // Start iterating and (as per the pseudocode), increment callCounter.
403
404 for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]405 for(BasicBlock::iterator i = b-&gt;begin(); ie = b-&gt;end(); i != ie; ++i) {
406 if(CallInst* callInst = dyn_cast<CallInst>(&amp;*inst)) {
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]407 // we know we've encountered a call instruction, so we
408 // need to determine if it's a call to foo or not
409
Joel Stanley72ef35e2002-09-06 23:05:12 +0000[diff] [blame]410 if(callInst-&gt;getCalledFunction() == foo)
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]411 ++callCounter;
412 }
413 }
414 }
415}
416</pre>
417
418We could then print out the value of callCounter (if we wanted to)
419inside the doFinalization method of our FunctionPass.
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]420
Chris Lattner1a3105b2002-09-09 05:49:39 +0000[diff] [blame]421
422<!--_______________________________________________________________________-->
423</ul><h4><a name="iterate_chains"><hr size=0>Iterating over def-use &amp;
424use-def chains</h4><ul>
425
426
427<!--
428 def-use chains ("finding all users of"): Value::use_begin/use_end
429 use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
430-->
431
Chris Lattnerae7f7592002-09-06 18:31:18 +0000[diff] [blame]432<!-- ======================================================================= -->
433</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
434<tr><td>&nbsp;</td><td width="100%">&nbsp;
435<font color="#EEEEFF" face="Georgia,Palatino"><b>
436<a name="simplechanges">Making simple changes</a>
437</b></font></td></tr></table><ul>
438
439<!-- Value::replaceAllUsesWith
440 User::replaceUsesOfWith
441 Point out: include/llvm/Transforms/Utils/
442 especially BasicBlockUtils.h with:
443 ReplaceInstWithValue, ReplaceInstWithInst
444
445-->
Chris Lattnerb99344f2002-09-06 16:40:10 +0000[diff] [blame]446
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]447
448<!-- *********************************************************************** -->
449</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
450<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Joel Stanley9b96c442002-09-06 21:55:13 +0000[diff] [blame]451<a name="coreclasses">The Core LLVM Class Hierarchy Reference
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]452</b></font></td></tr></table><ul>
453<!-- *********************************************************************** -->
454
455The Core LLVM classes are the primary means of representing the program being
456inspected or transformed. The core LLVM classes are defined in header files in
457the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
458directory.<p>
459
460
461<!-- ======================================================================= -->
462</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
463<tr><td>&nbsp;</td><td width="100%">&nbsp;
464<font color="#EEEEFF" face="Georgia,Palatino"><b>
465<a name="Value">The <tt>Value</tt> class</a>
466</b></font></td></tr></table><ul>
467
468<tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
469doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
470
471
472The <tt>Value</tt> class is the most important class in LLVM Source base. It
473represents a typed value that may be used (among other things) as an operand to
474an instruction. There are many different types of <tt>Value</tt>s, such as <a
475href="#Constant"><tt>Constant</tt></a>s, <a
476href="#Argument"><tt>Argument</tt></a>s, and even <a
477href="#Instruction"><tt>Instruction</tt></a>s and <a
478href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
479
480A particular <tt>Value</tt> may be used many times in the LLVM representation
481for a program. For example, an incoming argument to a function (represented
482with an instance of the <a href="#Argument">Argument</a> class) is "used" by
483every instruction in the function that references the argument. To keep track
484of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
485href="#User"><tt>User</tt></a>s that is using it (the <a
486href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
487graph 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]488def-use information in the program, and is accessible through the <tt>use_</tt>*
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]489methods, shown below.<p>
490
491Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
492this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
493method. <a name="#nameWarning">In addition, all LLVM values can be named. The
494"name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
495
496<pre>
497 %<b>foo</b> = add int 1, 2
498</pre>
499
500The name of this instruction is "foo". <b>NOTE</b> that the name of any value
501may be missing (an empty string), so names should <b>ONLY</b> be used for
502debugging (making the source code easier to read, debugging printouts), they
503should not be used to keep track of values or map between them. For this
504purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
505instead.<p>
506
507One important aspect of LLVM is that there is no distinction between an SSA
508variable and the operation that produces it. Because of this, any reference to
509the value produced by an instruction (or the value available as an incoming
510argument, for example) is represented as a direct pointer to the class that
511represents this value. Although this may take some getting used to, it
512simplifies the representation and makes it easier to manipulate.<p>
513
514
515<!-- _______________________________________________________________________ -->
516</ul><h4><a name="m_Value"><hr size=0>Important Public Members of
517the <tt>Value</tt> class</h4><ul>
518
519<li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
520 <tt>Value::use_const_iterator</tt>
521 - Typedef for const_iterator over the use-list<br>
522 <tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
523 <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
524 <tt>use_iterator use_begin()</tt>
525 - Get an iterator to the start of the use-list.<br>
526 <tt>use_iterator use_end()</tt>
527 - Get an iterator to the end of the use-list.<br>
528 <tt><a href="#User">User</a> *use_back()</tt>
529 - Returns the last element in the list.<p>
530
531These 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>
532
533<li><tt><a href="#Type">Type</a> *getType() const</tt><p>
534This method returns the Type of the Value.
535
536<li><tt>bool hasName() const</tt><br>
537 <tt>std::string getName() const</tt><br>
538 <tt>void setName(const std::string &amp;Name)</tt><p>
539
540This family of methods is used to access and assign a name to a <tt>Value</tt>,
541be aware of the <a href="#nameWarning">precaution above</a>.<p>
542
543
544<li><tt>void replaceAllUsesWith(Value *V)</tt><p>
545
546This method traverses the use list of a <tt>Value</tt> changing all <a
547href="#User"><tt>User</tt>'s</a> of the current value to refer to "<tt>V</tt>"
548instead. For example, if you detect that an instruction always produces a
549constant value (for example through constant folding), you can replace all uses
550of the instruction with the constant like this:<p>
551
552<pre>
553 Inst-&gt;replaceAllUsesWith(ConstVal);
554</pre><p>
555
556
557
558<!-- ======================================================================= -->
559</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
560<tr><td>&nbsp;</td><td width="100%">&nbsp;
561<font color="#EEEEFF" face="Georgia,Palatino"><b>
562<a name="User">The <tt>User</tt> class</a>
563</b></font></td></tr></table><ul>
564
565<tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
566doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
567Superclass: <a href="#Value"><tt>Value</tt></a><p>
568
569
570The <tt>User</tt> class is the common base class of all LLVM nodes that may
571refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
572that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
573referring to. The <tt>User</tt> class itself is a subclass of
574<tt>Value</tt>.<p>
575
576The operands of a <tt>User</tt> point directly to the LLVM <a
577href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
578Single Assignment (SSA) form, there can only be one definition referred to,
579allowing this direct connection. This connection provides the use-def
580information in LLVM.<p>
581
582<!-- _______________________________________________________________________ -->
583</ul><h4><a name="m_User"><hr size=0>Important Public Members of
584the <tt>User</tt> class</h4><ul>
585
586The <tt>User</tt> class exposes the operand list in two ways: through an index
587access interface and through an iterator based interface.<p>
588
589<li><tt>Value *getOperand(unsigned i)</tt><br>
590 <tt>unsigned getNumOperands()</tt><p>
591
592These two methods expose the operands of the <tt>User</tt> in a convenient form
593for direct access.<p>
594
595<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
596 <tt>User::op_const_iterator</tt>
597 <tt>use_iterator op_begin()</tt>
598 - Get an iterator to the start of the operand list.<br>
599 <tt>use_iterator op_end()</tt>
600 - Get an iterator to the end of the operand list.<p>
601
602Together, these methods make up the iterator based interface to the operands of
603a <tt>User</tt>.<p>
604
605
606
607<!-- ======================================================================= -->
608</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
609<tr><td>&nbsp;</td><td width="100%">&nbsp;
610<font color="#EEEEFF" face="Georgia,Palatino"><b>
611<a name="Instruction">The <tt>Instruction</tt> class</a>
612</b></font></td></tr></table><ul>
613
614<tt>#include "<a
615href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
616doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
617Superclasses: <a href="#User"><tt>User</tt></a>, <a
618href="#Value"><tt>Value</tt></a><p>
619
620The <tt>Instruction</tt> class is the common base class for all LLVM
621instructions. It provides only a few methods, but is a very commonly used
622class. The primary data tracked by the <tt>Instruction</tt> class itself is the
623opcode (instruction type) and the parent <a
624href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
625into. To represent a specific type of instruction, one of many subclasses of
626<tt>Instruction</tt> are used.<p>
627
628Because the <tt>Instruction</tt> class subclasses the <a
629href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
630way as for other <a href="#User"><tt>User</tt></a>s (with the
631<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
632<tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
633
634
635<!-- _______________________________________________________________________ -->
636</ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
637the <tt>Instruction</tt> class</h4><ul>
638
639<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
640
641Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
642<tt>Instruction</tt> is embedded into.<p>
643
644<li><tt>bool hasSideEffects()</tt><p>
645
646Returns true if the instruction has side effects, i.e. it is a <tt>call</tt>,
647<tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
648
649<li><tt>unsigned getOpcode()</tt><p>
650
651Returns the opcode for the <tt>Instruction</tt>.<p>
652
653<!--
654
655\subsection{Subclasses of Instruction :}
656\begin{itemize}
657<li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
658 \begin{itemize}
659 <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.
660 \end{itemize}
661<li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
662 \begin{itemize}
663 <li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
664 <li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
665 <li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
666 \end{itemize}
667
668<li>PHINode : This represents the PHI instructions in the SSA form.
669 \begin{itemize}
670 <li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
671 <li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
672 <li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
673 <li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
674 <li><tt> void addIncoming(Value *D, BasicBlock *BB)</tt>:
675 Add an incoming value to the end of the PHI list
676 <li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
677 Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
678 \end{itemize}
679<li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
680<li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
681 \begin{itemize}
682 <li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
683 \end{itemize}
684<li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
685 \begin{itemize}
686 <li><tt>Value * getPointerOperand ()</tt>: Returns the Pointer Operand which is typically the 0th operand.
687 \end{itemize}
688<li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
689 \begin{itemize}
690 <li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
691 <li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
692 <li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
693 \end{itemize}
694
695\end{itemize}
696
697-->
698
699
700<!-- ======================================================================= -->
701</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
702<tr><td>&nbsp;</td><td width="100%">&nbsp;
703<font color="#EEEEFF" face="Georgia,Palatino"><b>
704<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
705</b></font></td></tr></table><ul>
706
707<tt>#include "<a
708href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
709doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
710Superclass: <a href="#Value"><tt>Value</tt></a><p>
711
712
713This class represents a single entry multiple exit section of the code, commonly
714known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
715maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
716the body of the block. Matching the language definition, the last element of
717this list of instructions is always a terminator instruction (a subclass of the
718<a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
719
720In addition to tracking the list of instructions that make up the block, the
721<tt>BasicBlock</tt> class also keeps track of the <a
722href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
723
724Note that <tt>BasicBlock</tt>s themselves are <a
725href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
726like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
727<tt>label</tt>.<p>
728
729
730<!-- _______________________________________________________________________ -->
731</ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
732the <tt>BasicBlock</tt> class</h4><ul>
733
734<li><tt>BasicBlock(const std::string &amp;Name = "", <a
735href="#Function">Function</a> *Parent = 0)</tt><p>
736
737The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
738insertion into a function. The constructor simply takes a name for the new
739block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
740into. If the <tt>Parent</tt> parameter is specified, the new
741<tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
742href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
743manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
744
745<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
746 <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
747 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
748 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
749
750These methods and typedefs are forwarding functions that have the same semantics
751as the standard library methods of the same names. These methods expose the
752underlying instruction list of a basic block in a way that is easy to
753manipulate. To get the full complement of container operations (including
754operations to update the list), you must use the <tt>getInstList()</tt>
755method.<p>
756
757<li><tt>BasicBlock::InstListType &amp;getInstList()</tt><p>
758
759This method is used to get access to the underlying container that actually
760holds the Instructions. This method must be used when there isn't a forwarding
761function in the <tt>BasicBlock</tt> class for the operation that you would like
762to perform. Because there are no forwarding functions for "updating"
763operations, you need to use this if you want to update the contents of a
764<tt>BasicBlock</tt>.<p>
765
766<li><tt><A href="#Function">Function</a> *getParent()</tt><p>
767
768Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
769embedded into, or a null pointer if it is homeless.<p>
770
771<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
772
773Returns a pointer to the terminator instruction that appears at the end of the
774<tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
775instruction in the block is not a terminator, then a null pointer is
776returned.<p>
777
778
779<!-- ======================================================================= -->
780</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
781<tr><td>&nbsp;</td><td width="100%">&nbsp;
782<font color="#EEEEFF" face="Georgia,Palatino"><b>
783<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
784</b></font></td></tr></table><ul>
785
786<tt>#include "<a
787href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
788doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
789Superclasses: <a href="#User"><tt>User</tt></a>, <a
790href="#Value"><tt>Value</tt></a><p>
791
792Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
793href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
794visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
795Because they are visible at global scope, they are also subject to linking with
796other globals defined in different translation units. To control the linking
797process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
798<tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
799
800If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
801<tt>static</tt> in C), it is not visible to code outside the current translation
802unit, and does not participate in linking. If it has external linkage, it is
803visible to external code, and does participate in linking. In addition to
804linkage information, <tt>GlobalValue</tt>s keep track of which <a
805href="#Module"><tt>Module</tt></a> they are currently part of.<p>
806
807Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
808their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
809always a pointer to its contents. This is explained in the LLVM Language
810Reference Manual.<p>
811
812
813<!-- _______________________________________________________________________ -->
814</ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
815the <tt>GlobalValue</tt> class</h4><ul>
816
817<li><tt>bool hasInternalLinkage() const</tt><br>
818 <tt>bool hasExternalLinkage() const</tt><br>
819 <tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
820
821These methods manipulate the linkage characteristics of the
822<tt>GlobalValue</tt>.<p>
823
824<li><tt><a href="#Module">Module</a> *getParent()</tt><p>
825
826This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
827currently embedded into.<p>
828
829
830
831<!-- ======================================================================= -->
832</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
833<tr><td>&nbsp;</td><td width="100%">&nbsp;
834<font color="#EEEEFF" face="Georgia,Palatino"><b>
835<a name="Function">The <tt>Function</tt> class</a>
836</b></font></td></tr></table><ul>
837
838<tt>#include "<a
839href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
840doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
841Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
842href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
843
844The <tt>Function</tt> class represents a single procedure in LLVM. It is
845actually one of the more complex classes in the LLVM heirarchy because it must
846keep track of a large amount of data. The <tt>Function</tt> class keeps track
847of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
848href="#Argument"><tt>Argument</tt></a>s, and a <a
849href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
850
851The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
852used part of <tt>Function</tt> objects. The list imposes an implicit ordering
853of the blocks in the function, which indicate how the code will be layed out by
854the backend. Additionally, the first <a
855href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
856<tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
857block. There are no implicit exit nodes, and in fact there may be multiple exit
858nodes from a single <tt>Function</tt>. If the <a
859href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
860the <tt>Function</tt> is actually a function declaration: the actual body of the
861function hasn't been linked in yet.<p>
862
863In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
864<tt>Function</tt> class also keeps track of the list of formal <a
865href="#Argument"><tt>Argument</tt></a>s that the function receives. This
866container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
867nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
868the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
869
870The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
871feature that is only used when you have to look up a value by name. Aside from
872that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
873make sure that there are not conflicts between the names of <a
874href="#Instruction"><tt>Instruction</tt></a>s, <a
875href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
876href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
877
878
879<!-- _______________________________________________________________________ -->
880</ul><h4><a name="m_Function"><hr size=0>Important Public Members of
881the <tt>Function</tt> class</h4><ul>
882
883<li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &amp;N = "")</tt><p>
884
885Constructor used when you need to create new <tt>Function</tt>s to add the the
886program. The constructor must specify the type of the function to create and
887whether or not it should start out with internal or external linkage.<p>
888
889<li><tt>bool isExternal()</tt><p>
890
891Return whether or not the <tt>Function</tt> has a body defined. If the function
892is "external", it does not have a body, and thus must be resolved by linking
893with a function defined in a different translation unit.<p>
894
895
896<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
897 <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
898 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
899 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
900
901These are forwarding methods that make it easy to access the contents of a
902<tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
903list.<p>
904
905<li><tt>Function::BasicBlockListType &amp;getBasicBlockList()</tt><p>
906
907Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
908neccesary to use when you need to update the list or perform a complex action
909that doesn't have a forwarding method.<p>
910
911
912<li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
913 <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
914 <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
915 <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
916
917These are forwarding methods that make it easy to access the contents of a
918<tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
919
920<li><tt>Function::ArgumentListType &amp;getArgumentList()</tt><p>
921
922Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
923neccesary to use when you need to update the list or perform a complex action
924that doesn't have a forwarding method.<p>
925
926
927
928<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
929
930Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
931function. Because the entry block for the function is always the first block,
932this returns the first block of the <tt>Function</tt>.<p>
933
934<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
935 <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
936
937This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
938and returns the return type of the function, or the <a
939href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
940
941
942<li><tt>bool hasSymbolTable() const</tt><p>
943
944Return true if the <tt>Function</tt> has a symbol table allocated to it and if
945there is at least one entry in it.<p>
946
947<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
948
949Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
950<tt>Function</tt> or a null pointer if one has not been allocated (because there
951are no named values in the function).<p>
952
953<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
954
955Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
956<tt>Function</tt> or allocate a new <a
957href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
958should only be used when adding elements to the <a
959href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
960not left laying around.<p>
961
962
963
964<!-- ======================================================================= -->
965</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
966<tr><td>&nbsp;</td><td width="100%">&nbsp;
967<font color="#EEEEFF" face="Georgia,Palatino"><b>
968<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
969</b></font></td></tr></table><ul>
970
971<tt>#include "<a
972href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
973doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
974Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
975href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
976
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]977Global variables are represented with the (suprise suprise)
978<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
979also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
980are always referenced by their address (global values must live in memory, so
981their "name" refers to their address). Global variables may have an initial
982value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
983have an initializer, they may be marked as "constant" themselves (indicating
984that their contents never change at runtime).<p>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]985
986
987<!-- _______________________________________________________________________ -->
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]988</ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
989<tt>GlobalVariable</tt> class</h4><ul>
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]990
991<li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
992isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
993&amp;Name = "")</tt><p>
994
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]995Create a new global variable of the specified type. If <tt>isConstant</tt> is
996true then the global variable will be marked as unchanging for the program, and
997if <tt>isInternal</tt> is true the resultant global variable will have internal
998linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
999
1000
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1001<li><tt>bool isConstant() const</tt><p>
1002
1003Returns true if this is a global variable is known not to be modified at
1004runtime.<p>
1005
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1006
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1007<li><tt>bool hasInitializer()</tt><p>
1008
1009Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
1010
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1011
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1012<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
1013
Chris Lattner0377de42002-09-06 14:50:55 +0000[diff] [blame]1014Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
1015this method if there is no initializer.<p>
1016
1017
1018<!-- ======================================================================= -->
1019</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1020<tr><td>&nbsp;</td><td width="100%">&nbsp;
1021<font color="#EEEEFF" face="Georgia,Palatino"><b>
1022<a name="Module">The <tt>Module</tt> class</a>
1023</b></font></td></tr></table><ul>
1024
1025<tt>#include "<a
1026href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
1027doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
1028
1029The <tt>Module</tt> class represents the top level structure present in LLVM
1030programs. An LLVM module is effectively either a translation unit of the
1031original program or a combination of several translation units merged by the
1032linker. The <tt>Module</tt> class keeps track of a list of <a
1033href="#Function"><tt>Function</tt></a>s, a list of <a
1034href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
1035href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
1036helpful member functions that try to make common operations easy.<p>
1037
1038
1039<!-- _______________________________________________________________________ -->
1040</ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
1041<tt>Module</tt> class</h4><ul>
1042
1043<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
1044 <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
1045 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1046 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1047
1048These are forwarding methods that make it easy to access the contents of a
1049<tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
1050list.<p>
1051
1052<li><tt>Module::FunctionListType &amp;getFunctionList()</tt><p>
1053
1054Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
1055neccesary to use when you need to update the list or perform a complex action
1056that doesn't have a forwarding method.<p>
1057
1058<!-- Global Variable -->
1059<hr size=0>
1060
1061<li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
1062 <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
1063 <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
1064 <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
1065
1066These are forwarding methods that make it easy to access the contents of a
1067<tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
1068list.<p>
1069
1070<li><tt>Module::GlobalListType &amp;getGlobalList()</tt><p>
1071
1072Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
1073This is neccesary to use when you need to update the list or perform a complex
1074action that doesn't have a forwarding method.<p>
1075
1076
1077<!-- Symbol table stuff -->
1078<hr size=0>
1079
1080<li><tt>bool hasSymbolTable() const</tt><p>
1081
1082Return true if the <tt>Module</tt> has a symbol table allocated to it and if
1083there is at least one entry in it.<p>
1084
1085<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1086
1087Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1088<tt>Module</tt> or a null pointer if one has not been allocated (because there
1089are no named values in the function).<p>
1090
1091<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
1092
1093Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1094<tt>Module</tt> or allocate a new <a
1095href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
1096should only be used when adding elements to the <a
1097href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
1098not left laying around.<p>
1099
1100
1101<!-- Convenience methods -->
1102<hr size=0>
1103
1104<li><tt><a href="#Function">Function</a> *getFunction(const std::string &amp;Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt><p>
1105
1106Look up the specified function in the <tt>Module</tt> <a
1107href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
1108<tt>null</tt>.<p>
1109
1110
1111<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
1112 &amp;Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
1113
1114Look up the specified function in the <tt>Module</tt> <a
1115href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
1116external declaration for the function and return it.<p>
1117
1118
1119<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
1120
1121If there is at least one entry in the <a
1122href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
1123href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
1124string.<p>
1125
1126
1127<li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
1128*Ty)</tt><p>
1129
1130Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
1131<tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
1132is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
1133modified.<p>
1134
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1135
1136<!-- ======================================================================= -->
1137</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1138<tr><td>&nbsp;</td><td width="100%">&nbsp;
1139<font color="#EEEEFF" face="Georgia,Palatino"><b>
1140<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
1141</b></font></td></tr></table><ul>
1142
1143Constant represents a base class for different types of constants. It is
1144subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
1145ConstantArray etc for representing the various types of Constants.<p>
1146
1147
1148<!-- _______________________________________________________________________ -->
1149</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1150
1151<li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
1152
1153
1154
1155
1156\subsection{Important Subclasses of Constant}
1157\begin{itemize}
1158<li>ConstantSInt : This subclass of Constant represents a signed integer constant.
1159 \begin{itemize}
1160 <li><tt>int64_t getValue () const</tt>: Returns the underlying value of this constant.
1161 \end{itemize}
1162<li>ConstantUInt : This class represents an unsigned integer.
1163 \begin{itemize}
1164 <li><tt>uint64_t getValue () const</tt>: Returns the underlying value of this constant.
1165 \end{itemize}
1166<li>ConstantFP : This class represents a floating point constant.
1167 \begin{itemize}
1168 <li><tt>double getValue () const</tt>: Returns the underlying value of this constant.
1169 \end{itemize}
1170<li>ConstantBool : This represents a boolean constant.
1171 \begin{itemize}
1172 <li><tt>bool getValue () const</tt>: Returns the underlying value of this constant.
1173 \end{itemize}
1174<li>ConstantArray : This represents a constant array.
1175 \begin{itemize}
1176 <li><tt>const std::vector<Use> &amp;getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1177 \end{itemize}
1178<li>ConstantStruct : This represents a constant struct.
1179 \begin{itemize}
1180 <li><tt>const std::vector<Use> &amp;getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1181 \end{itemize}
1182<li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
1183 \begin{itemize}
1184<li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
1185 \end{itemize}
1186\end{itemize}
1187
1188
1189<!-- ======================================================================= -->
1190</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1191<tr><td>&nbsp;</td><td width="100%">&nbsp;
1192<font color="#EEEEFF" face="Georgia,Palatino"><b>
1193<a name="Type">The <tt>Type</tt> class and Derived Types</a>
1194</b></font></td></tr></table><ul>
1195
1196Type as noted earlier is also a subclass of a Value class. Any primitive
1197type (like int, short etc) in LLVM is an instance of Type Class. All
1198other types are instances of subclasses of type like FunctionType,
1199ArrayType etc. DerivedType is the interface for all such dervied types
1200including FunctionType, ArrayType, PointerType, StructType. Types can have
1201names. They can be recursive (StructType). There exists exactly one instance
1202of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
1203
1204<!-- _______________________________________________________________________ -->
1205</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1206
1207<li><tt>PrimitiveID getPrimitiveID () const</tt>: Returns the base type of the type.
1208<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.
1209<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.
1210<li><tt> bool isInteger () const</tt>: Equilivent to isSigned() || isUnsigned(), but with only a single virtual function invocation.
1211<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.
1212
1213<li><tt>bool isFloatingPoint ()</tt>: Return true if this is one of the two floating point types.
1214<li><tt>bool isRecursive () const</tt>: Returns rue if the type graph contains a cycle.
1215<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.
1216<li><tt>bool isPrimitiveType () const</tt>: Returns true if it is a primitive type.
1217<li><tt>bool isDerivedType () const</tt>: Returns true if it is a derived type.
1218<li><tt>const Type * getContainedType (unsigned i) const</tt>:
1219This 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.
1220<li><tt>unsigned getNumContainedTypes () const</tt>: Return the number of types in the derived type.
1221
1222
1223
1224\subsection{Derived Types}
1225\begin{itemize}
1226<li>SequentialType : This is subclassed by ArrayType and PointerType
1227 \begin{itemize}
1228 <li><tt>const Type * getElementType () const</tt>: Returns the type of each of the elements in the sequential type.
1229 \end{itemize}
1230<li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
1231 \begin{itemize}
1232 <li><tt>unsigned getNumElements () const</tt>: Returns the number of elements in the array.
1233 \end{itemize}
1234<li>PointerType : Subclass of SequentialType for pointer types.
1235<li>StructType : subclass of DerivedTypes for struct types
1236<li>FunctionType : subclass of DerivedTypes for function types.
1237 \begin{itemize}
1238
1239 <li><tt>bool isVarArg () const</tt>: Returns true if its a vararg function
1240 <li><tt> const Type * getReturnType () const</tt>: Returns the return type of the function.
1241 <li><tt> const ParamTypes &amp;getParamTypes () const</tt>: Returns a vector of parameter types.
1242 <li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
1243 <li><tt> const unsigned getNumParams () const</tt>: Returns the number of formal parameters.
1244 \end{itemize}
1245\end{itemize}
1246
1247
1248
1249
1250<!-- ======================================================================= -->
1251</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1252<tr><td>&nbsp;</td><td width="100%">&nbsp;
1253<font color="#EEEEFF" face="Georgia,Palatino"><b>
1254<a name="Argument">The <tt>Argument</tt> class</a>
1255</b></font></td></tr></table><ul>
1256
1257This subclass of Value defines the interface for incoming formal arguments to a
1258function. A Function maitanis a list of its formal arguments. An argument has a
1259pointer to the parent Function.
1260
1261
1262
1263
1264<!-- *********************************************************************** -->
1265</ul>
1266<!-- *********************************************************************** -->
1267
1268<hr><font size-1>
1269<address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
1270<a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1271<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
1272<!-- hhmts start -->
Chris Lattner1d43fd42002-09-09 05:53:21 +0000[diff] [blame]1273Last modified: Mon Sep 9 00:52:10 CDT 2002
Chris Lattner9355b472002-09-06 02:50:58 +0000[diff] [blame]1274<!-- hhmts end -->
1275</font></body></html>