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Chris Lattner9355b472002-09-06 02:50:58 +00006<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 Lattner986e0c92002-09-22 19:38:40 +000015<!--
16 <li>The <tt>-time-passes</tt> option
17 <li>How to use the LLVM Makefile system
18 <li>How to write a regression test
19-->
20 </ul>
21 <li><a href="#apis">Important and useful LLVM APIs</a>
22 <ul>
Chris Lattner1d43fd42002-09-09 05:53:21 +000023 <li><a href="#isa">The <tt>isa&lt;&gt;</tt>, <tt>cast&lt;&gt;</tt> and
24 <tt>dyn_cast&lt;&gt;</tt> templates</a>
Chris Lattner986e0c92002-09-22 19:38:40 +000025 <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro &amp;
26 <tt>-debug</tt> option</a>
27 <li><a href="#Statistic">The <tt>Statistic</tt> template &amp;
28 <tt>-stats</tt> option</a>
29<!--
30 <li>The <tt>InstVisitor</tt> template
31 <li>The general graph API
32-->
Chris Lattner9355b472002-09-06 02:50:58 +000033 </ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +000034 <li><a href="#common">Helpful Hints for Common Operations</a>
35 <ul>
36 <li><a href="#inspection">Basic Inspection and Traversal Routines</a>
37 <ul>
38 <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
39 in a <tt>Function</tt></a>
40 <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
41 in a <tt>BasicBlock</tt></a>
Chris Lattner1a3105b2002-09-09 05:49:39 +000042 <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
43 in a <tt>Function</tt></a>
Chris Lattnerae7f7592002-09-06 18:31:18 +000044 <li><a href="#iterate_convert">Turning an iterator into a class
45 pointer</a>
Chris Lattnerf1ebdc32002-09-06 22:09:21 +000046 <li><a href="#iterate_complex">Finding call sites: a more complex
47 example</a>
Chris Lattner1a3105b2002-09-09 05:49:39 +000048 <li><a href="#iterate_chains">Iterating over def-use &amp; use-def
49 chains</a>
Chris Lattnerae7f7592002-09-06 18:31:18 +000050 </ul>
51 <li><a href="#simplechanges">Making simple changes</a>
52 <ul>
Joel Stanley753eb712002-09-11 22:32:24 +000053 <li><a href="#schanges_creating">Creating and inserting new
54 <tt>Instruction</tt>s</a>
55 <li><a href="#schanges_deleting">Deleting
56 <tt>Instruction</tt>s</a>
57 <li><a href="#schanges_replacing">Replacing an
58 <tt>Instruction</tt> with another <tt>Value</tt></a>
Chris Lattnerae7f7592002-09-06 18:31:18 +000059 </ul>
60<!--
61 <li>Working with the Control Flow Graph
62 <ul>
63 <li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
64 <li>
65 <li>
66 </ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +000067-->
68 </ul>
Joel Stanley9b96c442002-09-06 21:55:13 +000069 <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
Chris Lattner9355b472002-09-06 02:50:58 +000070 <ul>
71 <li><a href="#Value">The <tt>Value</tt> class</a>
72 <ul>
73 <li><a href="#User">The <tt>User</tt> class</a>
74 <ul>
75 <li><a href="#Instruction">The <tt>Instruction</tt> class</a>
76 <ul>
77 <li>
Chris Lattner9355b472002-09-06 02:50:58 +000078 </ul>
79 <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
80 <ul>
81 <li><a href="#BasicBlock">The <tt>BasicBlock</tt> class</a>
82 <li><a href="#Function">The <tt>Function</tt> class</a>
83 <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a>
84 </ul>
85 <li><a href="#Module">The <tt>Module</tt> class</a>
86 <li><a href="#Constant">The <tt>Constant</tt> class</a>
87 <ul>
88 <li>
89 <li>
90 </ul>
91 </ul>
92 <li><a href="#Type">The <tt>Type</tt> class</a>
93 <li><a href="#Argument">The <tt>Argument</tt> class</a>
94 </ul>
95 <li>The <tt>SymbolTable</tt> class
96 <li>The <tt>ilist</tt> and <tt>iplist</tt> classes
97 <ul>
98 <li>Creating, inserting, moving and deleting from LLVM lists
99 </ul>
100 <li>Important iterator invalidation semantics to be aware of
101 </ul>
102
Chris Lattner6b121f12002-09-10 15:20:46 +0000103 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
104 <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>, and
Chris Lattnerf1ebdc32002-09-06 22:09:21 +0000105 <a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b><p>
Chris Lattner9355b472002-09-06 02:50:58 +0000106</ol>
107
108
109<!-- *********************************************************************** -->
110<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
111<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
112<a name="introduction">Introduction
113</b></font></td></tr></table><ul>
114<!-- *********************************************************************** -->
115
Joel Stanley9b96c442002-09-06 21:55:13 +0000116This document is meant to highlight some of the important classes and interfaces
117available in the LLVM source-base. This manual is not intended to explain what
Chris Lattner9355b472002-09-06 02:50:58 +0000118LLVM is, how it works, and what LLVM code looks like. It assumes that you know
119the basics of LLVM and are interested in writing transformations or otherwise
120analyzing or manipulating the code.<p>
121
122This document should get you oriented so that you can find your way in the
123continuously growing source code that makes up the LLVM infrastructure. Note
124that this manual is not intended to serve as a replacement for reading the
125source code, so if you think there should be a method in one of these classes to
126do something, but it's not listed, check the source. Links to the <a
127href="/doxygen/">doxygen</a> sources are provided to make this as easy as
128possible.<p>
129
130The first section of this document describes general information that is useful
131to know when working in the LLVM infrastructure, and the second describes the
132Core LLVM classes. In the future this manual will be extended with information
133describing how to use extension libraries, such as dominator information, CFG
134traversal routines, and useful utilities like the <tt><a
135href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.<p>
136
137
138<!-- *********************************************************************** -->
139</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
140<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
141<a name="general">General Information
142</b></font></td></tr></table><ul>
143<!-- *********************************************************************** -->
144
145This section contains general information that is useful if you are working in
146the LLVM source-base, but that isn't specific to any particular API.<p>
147
148
149<!-- ======================================================================= -->
150</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
151<tr><td>&nbsp;</td><td width="100%">&nbsp;
152<font color="#EEEEFF" face="Georgia,Palatino"><b>
153<a name="stl">The C++ Standard Template Library</a>
154</b></font></td></tr></table><ul>
155
156LLVM makes heavy use of the C++ Standard Template Library (STL), perhaps much
157more than you are used to, or have seen before. Because of this, you might want
158to do a little background reading in the techniques used and capabilities of the
159library. There are many good pages that discuss the STL, and several books on
160the subject that you can get, so it will not be discussed in this document.<p>
161
162Here are some useful links:<p>
163<ol>
Chris Lattnerab0577b2002-09-22 21:25:12 +0000164<li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++
Chris Lattner9355b472002-09-06 02:50:58 +0000165Library reference</a> - an excellent reference for the STL and other parts of
Chris Lattnere9ddc7f2002-10-21 02:38:02 +0000166the standard C++ library.
167
168<li><a href="http://www.tempest-sw.com/cpp/">C++ In a Nutshell</a> - This is an
169O'Reilly book in the making. It has a decent <a
170href="http://www.tempest-sw.com/cpp/ch13-libref.html">Standard Library
171Reference</a> that rivals Dinkumware's, and is actually free until the book is
172published.
Chris Lattner9355b472002-09-06 02:50:58 +0000173
174<li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
175Questions</a>
176
177<li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
178Contains a useful <a
179href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
180STL</a>.
181
182<li><a href="http://www.research.att.com/~bs/C++.html">Bjarne Stroustrup's C++
183Page</a>
184
185</ol><p>
186
187You are also encouraged to take a look at the <a
188href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
189to write maintainable code more than where to put your curly braces.<p>
190
191
Chris Lattner986e0c92002-09-22 19:38:40 +0000192<!-- *********************************************************************** -->
193</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
194<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
195<a name="apis">Important and useful LLVM APIs
196</b></font></td></tr></table><ul>
197<!-- *********************************************************************** -->
198
199Here we highlight some LLVM APIs that are generally useful and good to know
200about when writing transformations.<p>
201
Chris Lattner1d43fd42002-09-09 05:53:21 +0000202<!-- ======================================================================= -->
203</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
204<tr><td>&nbsp;</td><td width="100%">&nbsp;
205<font color="#EEEEFF" face="Georgia,Palatino"><b>
206<a name="isa">The isa&lt;&gt;, cast&lt;&gt; and dyn_cast&lt;&gt; templates</a>
207</b></font></td></tr></table><ul>
208
Chris Lattner979d9b72002-09-10 00:39:05 +0000209The LLVM source-base makes extensive use of a custom form of RTTI. These
210templates have many similarities to the C++ <tt>dynamic_cast&lt;&gt;</tt>
211operator, but they don't have some drawbacks (primarily stemming from the fact
212that <tt>dynamic_cast&lt;&gt;</tt> only works on classes that have a v-table).
213Because they are used so often, you must know what they do and how they work.
214All of these templates are defined in the <a
215href="/doxygen/Casting_8h-source.html"><tt>Support/Casting.h</tt></a> file (note
216that you very rarely have to include this file directly).<p>
Chris Lattner1d43fd42002-09-09 05:53:21 +0000217
Chris Lattner979d9b72002-09-10 00:39:05 +0000218<dl>
219
220<dt><tt>isa&lt;&gt;</tt>:
221
222<dd>The <tt>isa&lt;&gt;</tt> operator works exactly like the Java
223"<tt>instanceof</tt>" operator. It returns true or false depending on whether a
224reference or pointer points to an instance of the specified class. This can be
225very useful for constraint checking of various sorts (example below).<p>
226
227
228<dt><tt>cast&lt;&gt;</tt>:
229
230<dd>The <tt>cast&lt;&gt;</tt> operator is a "checked cast" operation. It
231converts a pointer or reference from a base class to a derived cast, causing an
232assertion failure if it is not really an instance of the right type. This
233should be used in cases where you have some information that makes you believe
234that something is of the right type. An example of the <tt>isa&lt;&gt;</tt> and
235<tt>cast&lt;&gt;</tt> template is:<p>
236
237<pre>
238static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const Loop *L) {
239 if (isa&lt;<a href="#Constant">Constant</a>&gt;(V) || isa&lt;<a href="#Argument">Argument</a>&gt;(V) || isa&lt;<a href="#GlobalValue">GlobalValue</a>&gt;(V))
240 return true;
241
242 <i>// Otherwise, it must be an instruction...</i>
243 return !L->contains(cast&lt;<a href="#Instruction">Instruction</a>&gt;(V)->getParent());
244</pre><p>
245
246Note that you should <b>not</b> use an <tt>isa&lt;&gt;</tt> test followed by a
247<tt>cast&lt;&gt;</tt>, for that use the <tt>dyn_cast&lt;&gt;</tt> operator.<p>
248
249
250<dt><tt>dyn_cast&lt;&gt;</tt>:
251
252<dd>The <tt>dyn_cast&lt;&gt;</tt> operator is a "checking cast" operation. It
253checks to see if the operand is of the specified type, and if so, returns a
254pointer to it (this operator does not work with references). If the operand is
255not of the correct type, a null pointer is returned. Thus, this works very much
256like the <tt>dynamic_cast</tt> operator in C++, and should be used in the same
Chris Lattner6b121f12002-09-10 15:20:46 +0000257circumstances. Typically, the <tt>dyn_cast&lt;&gt;</tt> operator is used in an
258<tt>if</tt> statement or some other flow control statement like this:<p>
259
260<pre>
261 if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast&lt;<a href="#AllocationInst">AllocationInst</a>&gt;(Val)) {
262 ...
263 }
264</pre><p>
265
266This form of the <tt>if</tt> statement effectively combines together a call to
267<tt>isa&lt;&gt;</tt> and a call to <tt>cast&lt;&gt;</tt> into one statement,
268which is very convenient.<p>
269
270Another common example is:<p>
Chris Lattner979d9b72002-09-10 00:39:05 +0000271
272<pre>
273 <i>// Loop over all of the phi nodes in a basic block</i>
274 BasicBlock::iterator BBI = BB->begin();
275 for (; <a href="#PhiNode">PHINode</a> *PN = dyn_cast&lt;<a href="#PHINode">PHINode</a>&gt;(&amp;*BBI); ++BBI)
276 cerr &lt;&lt; *PN;
277</pre><p>
278
Chris Lattner6b121f12002-09-10 15:20:46 +0000279Note that the <tt>dyn_cast&lt;&gt;</tt> operator, like C++'s
280<tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused. In
281particular you should not use big chained <tt>if/then/else</tt> blocks to check
282for lots of different variants of classes. If you find yourself wanting to do
283this, it is much cleaner and more efficient to use the InstVisitor class to
284dispatch over the instruction type directly.<p>
Chris Lattner979d9b72002-09-10 00:39:05 +0000285
286
Chris Lattner6b121f12002-09-10 15:20:46 +0000287<dt><tt>cast_or_null&lt;&gt;</tt>:
288
289<dd>The <tt>cast_or_null&lt;&gt;</tt> operator works just like the
290<tt>cast&lt;&gt;</tt> operator, except that it allows for a null pointer as an
Joel Stanley753eb712002-09-11 22:32:24 +0000291argument (which it then propagates). This can sometimes be useful, allowing you
Chris Lattner6b121f12002-09-10 15:20:46 +0000292to combine several null checks into one.<p>
293
294
295<dt><tt>dyn_cast_or_null&lt;&gt;</tt>:
296
297<dd>The <tt>dyn_cast_or_null&lt;&gt;</tt> operator works just like the
298<tt>dyn_cast&lt;&gt;</tt> operator, except that it allows for a null pointer as
Joel Stanley753eb712002-09-11 22:32:24 +0000299an argument (which it then propagates). This can sometimes be useful, allowing
Chris Lattner6b121f12002-09-10 15:20:46 +0000300you to combine several null checks into one.<p>
301
Chris Lattner979d9b72002-09-10 00:39:05 +0000302</dl>
Chris Lattner1d43fd42002-09-09 05:53:21 +0000303
Chris Lattner6b121f12002-09-10 15:20:46 +0000304These five templates can be used with any classes, whether they have a v-table
305or not. To add support for these templates, you simply need to add
306<tt>classof</tt> static methods to the class you are interested casting to.
307Describing this is currently outside the scope of this document, but there are
Joel Stanley753eb712002-09-11 22:32:24 +0000308lots of examples in the LLVM source base.<p>
Chris Lattner1d43fd42002-09-09 05:53:21 +0000309
310
Chris Lattner986e0c92002-09-22 19:38:40 +0000311<!-- ======================================================================= -->
312</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
313<tr><td>&nbsp;</td><td width="100%">&nbsp;
314<font color="#EEEEFF" face="Georgia,Palatino"><b>
315<a name="DEBUG">The <tt>DEBUG()</tt> macro &amp; <tt>-debug</tt> option</a>
316</b></font></td></tr></table><ul>
317
318Often when working on your pass you will put a bunch of debugging printouts and
319other code into your pass. After you get it working, you want to remove
320it... but you may need it again in the future (to work out new bugs that you run
321across).<p>
322
323Naturally, because of this, you don't want to delete the debug printouts, but
324you don't want them to always be noisy. A standard compromise is to comment
325them out, allowing you to enable them if you need them in the future.<p>
326
327The "<tt><a
Chris Lattner8328f1d2002-10-01 22:39:41 +0000328href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>"
Chris Lattner986e0c92002-09-22 19:38:40 +0000329file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to
330this problem. Basically, you can put arbitrary code into the argument of the
331<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' is run with the
332'<tt>-debug</tt>' command line argument:
333
334<pre>
335 ...
336 DEBUG(std::cerr &lt;&lt; "I am here!\n");
337 ...
338</pre><p>
339
340Then you can run your pass like this:<p>
341
342<pre>
343 $ opt &lt; a.bc &gt; /dev/null -mypass
344 &lt;no output&gt;
345 $ opt &lt; a.bc &gt; /dev/null -mypass -debug
346 I am here!
347 $
348</pre><p>
349
350Using the <tt>DEBUG()</tt> macro instead of a home brewed solution allows you to
351now have to create "yet another" command line option for the debug output for
Chris Lattnera4e7c4e2002-11-08 06:50:02 +0000352your pass. Note that <tt>DEBUG()</tt> macros are disabled for optimized builds,
353so they do not cause a performance impact at all (for the same reason, they
354should also not contain side-effects!).<p>
355
356One additional nice thing about the <tt>DEBUG()</tt> macro is that you can
357enable or disable it directly in gdb. Just use "<tt>set DebugFlag=0</tt>" or
358"<tt>set DebugFlag=1</tt>" from the gdb if the program is running. If the
359program hasn't been started yet, you can always just run it with
360<tt>-debug</tt>.<p>
Chris Lattner986e0c92002-09-22 19:38:40 +0000361
362
363<!-- ======================================================================= -->
364</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
365<tr><td>&nbsp;</td><td width="100%">&nbsp;
366<font color="#EEEEFF" face="Georgia,Palatino"><b>
367<a name="Statistic">The <tt>Statistic</tt> template &amp; <tt>-stats</tt>
368option</a>
369</b></font></td></tr></table><ul>
370
371The "<tt><a
Chris Lattner8328f1d2002-10-01 22:39:41 +0000372href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>"
Chris Lattner986e0c92002-09-22 19:38:40 +0000373file provides a template named <tt>Statistic</tt> that is used as a unified way
374to keeping track of what the LLVM compiler is doing and how effective various
375optimizations are. It is useful to see what optimizations are contributing to
376making a particular program run faster.<p>
377
378Often you may run your pass on some big program, and you're interested to see
379how many times it makes a certain transformation. Although you can do this with
380hand inspection, or some ad-hoc method, this is a real pain and not very useful
381for big programs. Using the <tt>Statistic</tt> template makes it very easy to
382keep track of this information, and the calculated information is presented in a
383uniform manner with the rest of the passes being executed.<p>
384
385There are many examples of <tt>Statistic</tt> users, but this basics of using it
386are as follows:<p>
387
388<ol>
389<li>Define your statistic like this:<p>
390
391<pre>
Chris Lattner8328f1d2002-10-01 22:39:41 +0000392static Statistic&lt;&gt; NumXForms("mypassname", "The # of times I did stuff");
Chris Lattner986e0c92002-09-22 19:38:40 +0000393</pre><p>
394
395The <tt>Statistic</tt> template can emulate just about any data-type, but if you
396do not specify a template argument, it defaults to acting like an unsigned int
397counter (this is usually what you want).<p>
398
399<li>Whenever you make a transformation, bump the counter:<p>
400
401<pre>
402 ++NumXForms; // I did stuff
403</pre><p>
404
405</ol><p>
406
407That's all you have to do. To get '<tt>opt</tt>' to print out the statistics
408gathered, use the '<tt>-stats</tt>' option:<p>
409
410<pre>
411 $ opt -stats -mypassname &lt; program.bc &gt; /dev/null
412 ... statistic output ...
413</pre><p>
414
415When running <tt>gccas</tt> on a C file from the SPEC benchmark suite, it gives
416a report that looks like this:<p>
417
418<pre>
419 7646 bytecodewriter - Number of normal instructions
420 725 bytecodewriter - Number of oversized instructions
421 129996 bytecodewriter - Number of bytecode bytes written
422 2817 raise - Number of insts DCEd or constprop'd
423 3213 raise - Number of cast-of-self removed
424 5046 raise - Number of expression trees converted
425 75 raise - Number of other getelementptr's formed
426 138 raise - Number of load/store peepholes
427 42 deadtypeelim - Number of unused typenames removed from symtab
428 392 funcresolve - Number of varargs functions resolved
429 27 globaldce - Number of global variables removed
430 2 adce - Number of basic blocks removed
431 134 cee - Number of branches revectored
432 49 cee - Number of setcc instruction eliminated
433 532 gcse - Number of loads removed
434 2919 gcse - Number of instructions removed
435 86 indvars - Number of cannonical indvars added
436 87 indvars - Number of aux indvars removed
437 25 instcombine - Number of dead inst eliminate
438 434 instcombine - Number of insts combined
439 248 licm - Number of load insts hoisted
440 1298 licm - Number of insts hoisted to a loop pre-header
441 3 licm - Number of insts hoisted to multiple loop preds (bad, no loop pre-header)
442 75 mem2reg - Number of alloca's promoted
443 1444 cfgsimplify - Number of blocks simplified
444</pre><p>
445
446Obviously, with so many optimizations, having a unified framework for this stuff
447is very nice. Making your pass fit well into the framework makes it more
448maintainable and useful.<p>
449
Chris Lattnerae7f7592002-09-06 18:31:18 +0000450
Chris Lattnerb99344f2002-09-06 16:40:10 +0000451<!-- *********************************************************************** -->
452</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
453<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
454<a name="common">Helpful Hints for Common Operations
Chris Lattner986e0c92002-09-22 19:38:40 +0000455</b></font></td></tr></table><ul> <!--
456*********************************************************************** -->
Chris Lattnerb99344f2002-09-06 16:40:10 +0000457
Chris Lattnerae7f7592002-09-06 18:31:18 +0000458This section describes how to perform some very simple transformations of LLVM
459code. This is meant to give examples of common idioms used, showing the
460practical side of LLVM transformations.<p>
461
Joel Stanley9b96c442002-09-06 21:55:13 +0000462Because this is a "how-to" section, you should also read about the main classes
Chris Lattnerae7f7592002-09-06 18:31:18 +0000463that you will be working with. The <a href="#coreclasses">Core LLVM Class
Joel Stanley9b96c442002-09-06 21:55:13 +0000464Hierarchy Reference</a> contains details and descriptions of the main classes
Chris Lattnerae7f7592002-09-06 18:31:18 +0000465that you should know about.<p>
466
467<!-- NOTE: this section should be heavy on example code -->
468
469
470<!-- ======================================================================= -->
471</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
472<tr><td>&nbsp;</td><td width="100%">&nbsp;
473<font color="#EEEEFF" face="Georgia,Palatino"><b>
474<a name="inspection">Basic Inspection and Traversal Routines</a>
475</b></font></td></tr></table><ul>
476
Chris Lattnercaa5d132002-09-09 19:58:18 +0000477The LLVM compiler infrastructure have many different data structures that may be
478traversed. Following the example of the C++ standard template library, the
479techniques used to traverse these various data structures are all basically the
480same. For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or
481method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt>
482function returns an iterator pointing to one past the last valid element of the
483sequence, and there is some <tt>XXXiterator</tt> data type that is common
484between the two operations.<p>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000485
Chris Lattnercaa5d132002-09-09 19:58:18 +0000486Because the pattern for iteration is common across many different aspects of the
487program representation, the standard template library algorithms may be used on
488them, and it is easier to remember how to iterate. First we show a few common
489examples of the data structures that need to be traversed. Other data
490structures are traversed in very similar ways.<p>
491
Chris Lattnerae7f7592002-09-06 18:31:18 +0000492
493<!-- _______________________________________________________________________ -->
Chris Lattnercaa5d132002-09-09 19:58:18 +0000494</ul><h4><a name="iterate_function"><hr size=0>Iterating over the <a
495href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a
496href="#Function"><tt>Function</tt></a> </h4><ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000497
Joel Stanley9b96c442002-09-06 21:55:13 +0000498It's quite common to have a <tt>Function</tt> instance that you'd like
499to transform in some way; in particular, you'd like to manipulate its
500<tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over
501all of the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>.
502The following is an example that prints the name of a
503<tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s it
504contains:
Chris Lattnerae7f7592002-09-06 18:31:18 +0000505
Joel Stanley9b96c442002-09-06 21:55:13 +0000506<pre>
507 // func is a pointer to a Function instance
508 for(Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {
509
510 // print out the name of the basic block if it has one, and then the
511 // number of instructions that it contains
512
Joel Stanley72ef35e2002-09-06 23:05:12 +0000513 cerr &lt;&lt "Basic block (name=" &lt;&lt i-&gt;getName() &lt;&lt; ") has "
514 &lt;&lt i-&gt;size() &lt;&lt " instructions.\n";
Joel Stanley9b96c442002-09-06 21:55:13 +0000515 }
516</pre>
517
518Note that i can be used as if it were a pointer for the purposes of
519invoking member functions of the <tt>Instruction</tt> class. This is
520because the indirection operator is overloaded for the iterator
521classes. In the above code, the expression <tt>i->size()</tt> is
522exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.
Chris Lattnerae7f7592002-09-06 18:31:18 +0000523
524<!-- _______________________________________________________________________ -->
Chris Lattnercaa5d132002-09-09 19:58:18 +0000525</ul><h4><a name="iterate_basicblock"><hr size=0>Iterating over the <a
526href="#Instruction"><tt>Instruction</tt></a>s in a <a
527href="#BasicBlock"><tt>BasicBlock</tt></a> </h4><ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000528
Joel Stanleyaaeb1c12002-09-06 23:42:40 +0000529Just like when dealing with <tt>BasicBlock</tt>s in
530<tt>Function</tt>s, it's easy to iterate over the individual
531instructions that make up <tt>BasicBlock</tt>s. Here's a code snippet
532that prints out each instruction in a <tt>BasicBlock</tt>:
Chris Lattnerae7f7592002-09-06 18:31:18 +0000533
Joel Stanley9b96c442002-09-06 21:55:13 +0000534<pre>
535 // blk is a pointer to a BasicBlock instance
Chris Lattnercaa5d132002-09-09 19:58:18 +0000536 for(BasicBlock::iterator i = blk-&gt;begin(), e = blk-&gt;end(); i != e; ++i)
Chris Lattner2b763062002-09-06 22:51:10 +0000537 // the next statement works since operator&lt;&lt;(ostream&amp;,...)
538 // is overloaded for Instruction&amp;
Chris Lattnercaa5d132002-09-09 19:58:18 +0000539 cerr &lt;&lt; *i &lt;&lt; "\n";
Joel Stanley9b96c442002-09-06 21:55:13 +0000540</pre>
541
542However, this isn't really the best way to print out the contents of a
543<tt>BasicBlock</tt>! Since the ostream operators are overloaded for
544virtually anything you'll care about, you could have just invoked the
Chris Lattner2b763062002-09-06 22:51:10 +0000545print routine on the basic block itself: <tt>cerr &lt;&lt; *blk &lt;&lt;
546"\n";</tt>.<p>
547
548Note that currently operator&lt;&lt; is implemented for <tt>Value*</tt>, so it
549will print out the contents of the pointer, instead of
550the pointer value you might expect. This is a deprecated interface that will
551be removed in the future, so it's best not to depend on it. To print out the
552pointer value for now, you must cast to <tt>void*</tt>.<p>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000553
Chris Lattnercaa5d132002-09-09 19:58:18 +0000554
Chris Lattnerae7f7592002-09-06 18:31:18 +0000555<!-- _______________________________________________________________________ -->
Chris Lattnercaa5d132002-09-09 19:58:18 +0000556</ul><h4><a name="iterate_institer"><hr size=0>Iterating over the <a
557href="#Instruction"><tt>Instruction</tt></a>s in a <a
558href="#Function"><tt>Function</tt></a></h4><ul>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000559
Joel Stanleye7be6502002-09-09 15:50:33 +0000560If you're finding that you commonly iterate over a <tt>Function</tt>'s
561<tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s
562<tt>Instruction</tt>s, <tt>InstIterator</tt> should be used instead.
Chris Lattnercaa5d132002-09-09 19:58:18 +0000563You'll need to include <a href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>, and then
Joel Stanleye7be6502002-09-09 15:50:33 +0000564instantiate <tt>InstIterator</tt>s explicitly in your code. Here's a
565small example that shows how to dump all instructions in a function to
566stderr (<b>Note:</b> Dereferencing an <tt>InstIterator</tt> yields an
567<tt>Instruction*</tt>, <i>not</i> an <tt>Instruction&amp</tt>!):
Chris Lattner1a3105b2002-09-09 05:49:39 +0000568
Joel Stanleye7be6502002-09-09 15:50:33 +0000569<pre>
Chris Lattnercaa5d132002-09-09 19:58:18 +0000570#include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"
Joel Stanleye7be6502002-09-09 15:50:33 +0000571...
572// Suppose F is a ptr to a function
573for(inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
574 cerr &lt;&lt **i &lt;&lt "\n";
575</pre>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000576
Joel Stanleye7be6502002-09-09 15:50:33 +0000577Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
578worklist with its initial contents. For example, if you wanted to
579initialize a worklist to contain all instructions in a
580<tt>Function</tt> F, all you would need to do is something like:
Chris Lattner1a3105b2002-09-09 05:49:39 +0000581
Joel Stanleye7be6502002-09-09 15:50:33 +0000582<pre>
583std::set&lt;Instruction*&gt worklist;
584worklist.insert(inst_begin(F), inst_end(F));
585</pre>
Chris Lattner1a3105b2002-09-09 05:49:39 +0000586
Joel Stanleye7be6502002-09-09 15:50:33 +0000587The STL set <tt>worklist</tt> would now contain all instructions in
588the <tt>Function</tt> pointed to by F.
Chris Lattner1a3105b2002-09-09 05:49:39 +0000589
590<!-- _______________________________________________________________________ -->
Chris Lattnerae7f7592002-09-06 18:31:18 +0000591</ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
Joel Stanleye7be6502002-09-09 15:50:33 +0000592pointer (and vice-versa) </h4><ul>
Chris Lattnerae7f7592002-09-06 18:31:18 +0000593
Joel Stanley9b96c442002-09-06 21:55:13 +0000594Sometimes, it'll be useful to grab a reference (or pointer) to a class
595instance when all you've got at hand is an iterator. Well, extracting
596a reference or a pointer from an iterator is very straightforward.
597Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
598<tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
599
600<pre>
Chris Lattner83b5ee02002-09-06 22:12:58 +0000601 Instruction&amp; inst = *i; // grab reference to instruction reference
602 Instruction* pinst = &amp;*i; // grab pointer to instruction reference
603 const Instruction&amp; inst = *j;
Joel Stanley9b96c442002-09-06 21:55:13 +0000604</pre>
605However, the iterators you'll be working with in the LLVM framework
606are special: they will automatically convert to a ptr-to-instance type
607whenever they need to. Instead of dereferencing the iterator and then
608taking the address of the result, you can simply assign the iterator
609to the proper pointer type and you get the dereference and address-of
610operation as a result of the assignment (behind the scenes, this is a
611result of overloading casting mechanisms). Thus the last line of the
612last example,
613
Chris Lattner83b5ee02002-09-06 22:12:58 +0000614<pre>Instruction* pinst = &amp;*i;</pre>
Joel Stanley9b96c442002-09-06 21:55:13 +0000615
616is semantically equivalent to
617
618<pre>Instruction* pinst = i;</pre>
619
Chris Lattner979d9b72002-09-10 00:39:05 +0000620<b>Caveat emptor</b>: The above syntax works <i>only</i> when you're <i>not</i>
621working with <tt>dyn_cast</tt>. The template definition of <tt><a
622href="#isa">dyn_cast</a></tt> isn't implemented to handle this yet, so you'll
Joel Stanley9b96c442002-09-06 21:55:13 +0000623still need the following in order for things to work properly:
624
625<pre>
626BasicBlock::iterator bbi = ...;
Chris Lattnercaa5d132002-09-09 19:58:18 +0000627<a href="#BranchInst">BranchInst</a>* b = <a href="#isa">dyn_cast</a>&lt;<a href="#BranchInst">BranchInst</a>&gt;(&amp;*bbi);
Joel Stanley9b96c442002-09-06 21:55:13 +0000628</pre>
629
Joel Stanleye7be6502002-09-09 15:50:33 +0000630It's also possible to turn a class pointer into the corresponding
631iterator. Usually, this conversion is quite inexpensive. The
632following code snippet illustrates use of the conversion constructors
633provided by LLVM iterators. By using these, you can explicitly grab
634the iterator of something without actually obtaining it via iteration
635over some structure:
Joel Stanley9b96c442002-09-06 21:55:13 +0000636
637<pre>
638void printNextInstruction(Instruction* inst) {
639 BasicBlock::iterator it(inst);
640 ++it; // after this line, it refers to the instruction after *inst.
Chris Lattnercaa5d132002-09-09 19:58:18 +0000641 if(it != inst-&gt;getParent()->end()) cerr &lt;&lt; *it &lt;&lt; "\n";
Joel Stanley9b96c442002-09-06 21:55:13 +0000642}
643</pre>
Joel Stanleyaaeb1c12002-09-06 23:42:40 +0000644Of course, this example is strictly pedagogical, because it'd be much
645better to explicitly grab the next instruction directly from inst.
Joel Stanley9b96c442002-09-06 21:55:13 +0000646
Chris Lattnerae7f7592002-09-06 18:31:18 +0000647
Chris Lattner1a3105b2002-09-09 05:49:39 +0000648<!--_______________________________________________________________________-->
649</ul><h4><a name="iterate_complex"><hr size=0>Finding call sites: a slightly
650more complex example </h4><ul>
Joel Stanley9b96c442002-09-06 21:55:13 +0000651
652Say that you're writing a FunctionPass and would like to count all the
Joel Stanleye7be6502002-09-09 15:50:33 +0000653locations in the entire module (that is, across every
Joel Stanleyd8aabb22002-09-09 16:29:58 +0000654<tt>Function</tt>) where a certain function (i.e. some
655<tt>Function</tt>*) already in scope. As you'll learn later, you may
656want to use an <tt>InstVisitor</tt> to accomplish this in a much more
657straightforward manner, but this example will allow us to explore how
658you'd do it if you didn't have <tt>InstVisitor</tt> around. In
Joel Stanleye7be6502002-09-09 15:50:33 +0000659pseudocode, this is what we want to do:
Joel Stanley9b96c442002-09-06 21:55:13 +0000660
661<pre>
662initialize callCounter to zero
663for each Function f in the Module
664 for each BasicBlock b in f
665 for each Instruction i in b
Joel Stanleye7be6502002-09-09 15:50:33 +0000666 if(i is a CallInst and calls the given function)
Joel Stanley9b96c442002-09-06 21:55:13 +0000667 increment callCounter
668</pre>
669
670And the actual code is (remember, since we're writing a
Joel Stanleyd8aabb22002-09-09 16:29:58 +0000671<tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply
Joel Stanley9b96c442002-09-06 21:55:13 +0000672has to override the <tt>runOnFunction</tt> method...):
673
674<pre>
Joel Stanleyd8aabb22002-09-09 16:29:58 +0000675Function* targetFunc = ...;
676
Joel Stanleye7be6502002-09-09 15:50:33 +0000677class OurFunctionPass : public FunctionPass {
678 public:
Joel Stanleyd8aabb22002-09-09 16:29:58 +0000679 OurFunctionPass(): callCounter(0) { }
Joel Stanley9b96c442002-09-06 21:55:13 +0000680
Chris Lattnercaa5d132002-09-09 19:58:18 +0000681 virtual runOnFunction(Function&amp; F) {
Joel Stanleye7be6502002-09-09 15:50:33 +0000682 for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
683 for(BasicBlock::iterator i = b-&gt;begin(); ie = b-&gt;end(); i != ie; ++i) {
Chris Lattnera9030cb2002-09-16 22:08:07 +0000684 if (<a href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a>&lt;<a href="#CallInst">CallInst</a>&gt;(&amp;*i)) {
Joel Stanleye7be6502002-09-09 15:50:33 +0000685 // we know we've encountered a call instruction, so we
686 // need to determine if it's a call to the
687 // function pointed to by m_func or not.
688
Joel Stanleyd8aabb22002-09-09 16:29:58 +0000689 if(callInst-&gt;getCalledFunction() == targetFunc)
Joel Stanleye7be6502002-09-09 15:50:33 +0000690 ++callCounter;
691 }
692 }
Joel Stanley9b96c442002-09-06 21:55:13 +0000693 }
Joel Stanleye7be6502002-09-09 15:50:33 +0000694
695 private:
Joel Stanleyd8aabb22002-09-09 16:29:58 +0000696 unsigned callCounter;
Joel Stanleye7be6502002-09-09 15:50:33 +0000697};
Joel Stanley9b96c442002-09-06 21:55:13 +0000698</pre>
699
Chris Lattner1a3105b2002-09-09 05:49:39 +0000700<!--_______________________________________________________________________-->
701</ul><h4><a name="iterate_chains"><hr size=0>Iterating over def-use &amp;
702use-def chains</h4><ul>
703
Joel Stanley01040b22002-09-11 20:50:04 +0000704Frequently, we might have an instance of the <a
705href="/doxygen/classValue.html">Value Class</a> and we want to
706determine which <tt>User</tt>s use the <tt>Value</tt>. The list of
707all <tt>User</tt>s of a particular <tt>Value</tt> is called a
708<i>def-use</i> chain. For example, let's say we have a
709<tt>Function*</tt> named <tt>F</tt> to a particular function
710<tt>foo</tt>. Finding all of the instructions that <i>use</i>
711<tt>foo</tt> is as simple as iterating over the <i>def-use</i> chain of
712<tt>F</tt>:
713
714<pre>
715Function* F = ...;
716
717for(Value::use_iterator i = F-&gt;use_begin(), e = F-&gt;use_end(); i != e; ++i) {
Chris Lattner24b70922002-09-17 22:43:00 +0000718 if(Instruction* Inst = dyn_cast&lt;Instruction&gt;(*i)) {
719 cerr &lt;&lt; "F is used in instruction:\n";
720 cerr &lt;&lt; *Inst &lt;&lt; "\n";
Joel Stanley01040b22002-09-11 20:50:04 +0000721 }
722}
723</pre>
724
725Alternately, it's common to have an instance of the <a
726href="/doxygen/classUser.html">User Class</a> and need to know what
727<tt>Value</tt>s are used by it. The list of all <tt>Value</tt>s used
728by a <tt>User</tt> is known as a <i>use-def</i> chain. Instances of
729class <tt>Instruction</tt> are common <tt>User</tt>s, so we might want
730to iterate over all of the values that a particular instruction uses
731(that is, the operands of the particular <tt>Instruction</tt>):
732
733<pre>
734Instruction* pi = ...;
735
736for(User::op_iterator i = pi-&gt;op_begin(), e = pi-&gt;op_end(); i != e; ++i) {
Joel Stanley753eb712002-09-11 22:32:24 +0000737 Value* v = *i;
Joel Stanley01040b22002-09-11 20:50:04 +0000738 ...
739}
740</pre>
741
742
Chris Lattner1a3105b2002-09-09 05:49:39 +0000743<!--
744 def-use chains ("finding all users of"): Value::use_begin/use_end
745 use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
746-->
747
Chris Lattnerae7f7592002-09-06 18:31:18 +0000748<!-- ======================================================================= -->
749</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
750<tr><td>&nbsp;</td><td width="100%">&nbsp;
751<font color="#EEEEFF" face="Georgia,Palatino"><b>
752<a name="simplechanges">Making simple changes</a>
753</b></font></td></tr></table><ul>
754
Joel Stanley753eb712002-09-11 22:32:24 +0000755There are some primitive transformation operations present in the LLVM
756infrastructure that are worth knowing about. When performing
757transformations, it's fairly common to manipulate the contents of
758basic blocks. This section describes some of the common methods for
759doing so and gives example code.
760
761<!--_______________________________________________________________________-->
762</ul><h4><a name="schanges_creating"><hr size=0>Creating and inserting
763 new <tt>Instruction</tt>s</h4><ul>
764
765<i>Instantiating Instructions</i>
766
767<p>Creation of <tt>Instruction</tt>s is straightforward: simply call the
768constructor for the kind of instruction to instantiate and provide the
769necessary parameters. For example, an <tt>AllocaInst</tt> only
770<i>requires</i> a (const-ptr-to) <tt>Type</tt>. Thus:
771
772<pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre>
773
774will create an <tt>AllocaInst</tt> instance that represents the
775allocation of one integer in the current stack frame, at runtime.
776Each <tt>Instruction</tt> subclass is likely to have varying default
777parameters which change the semantics of the instruction, so refer to
Chris Lattner4e1f96b2002-09-12 19:06:51 +0000778the <a href="/doxygen/classInstruction.html">doxygen documentation for
Joel Stanley753eb712002-09-11 22:32:24 +0000779the subclass of Instruction</a> that you're interested in
780instantiating.</p>
781
782<p><i>Naming values</i></p>
783
784<p>
785It is very useful to name the values of instructions when you're able
786to, as this facilitates the debugging of your transformations. If you
787end up looking at generated LLVM machine code, you definitely want to
788have logical names associated with the results of instructions! By
789supplying a value for the <tt>Name</tt> (default) parameter of the
790<tt>Instruction</tt> constructor, you associate a logical name with
791the result of the instruction's execution at runtime. For example,
792say that I'm writing a transformation that dynamically allocates space
793for an integer on the stack, and that integer is going to be used as
794some kind of index by some other code. To accomplish this, I place an
795<tt>AllocaInst</tt> at the first point in the first
796<tt>BasicBlock</tt> of some <tt>Function</tt>, and I'm intending to
797use it within the same <tt>Function</tt>. I might do:
798
799<pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre>
800
801where <tt>indexLoc</tt> is now the logical name of the instruction's
802execution value, which is a pointer to an integer on the runtime
803stack.
804</p>
805
806<p><i>Inserting instructions</i></p>
807
808<p>
809There are essentially two ways to insert an <tt>Instruction</tt> into
810an existing sequence of instructions that form a <tt>BasicBlock</tt>:
811<ul>
812<li>Insertion into an explicit instruction list
813
814<p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> within
815that <tt>BasicBlock</tt>, and a newly-created instruction
816we wish to insert before <tt>*pi</tt>, we do the following:
817
818<pre>
819BasicBlock* pb = ...;
820Instruction* pi = ...;
821Instruction* newInst = new Instruction(...);
822pb->getInstList().insert(pi, newInst); // inserts newInst before pi in pb
823</pre>
824</p>
825
826<li>Insertion into an implicit instruction list
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000827<p><tt>Instruction</tt> instances that are already in
Joel Stanley753eb712002-09-11 22:32:24 +0000828<tt>BasicBlock</tt>s are implicitly associated with an existing
829instruction list: the instruction list of the enclosing basic block.
830Thus, we could have accomplished the same thing as the above code
831without being given a <tt>BasicBlock</tt> by doing:
832<pre>
833Instruction* pi = ...;
834Instruction* newInst = new Instruction(...);
835pi->getParent()->getInstList().insert(pi, newInst);
836</pre>
837In fact, this sequence of steps occurs so frequently that the
838<tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes
839provide constructors which take (as a default parameter) a pointer to
840an <tt>Instruction</tt> which the newly-created <tt>Instruction</tt>
841should precede. That is, <tt>Instruction</tt> constructors are
842capable of inserting the newly-created instance into the
843<tt>BasicBlock</tt> of a provided instruction, immediately before that
844instruction. Using an <tt>Instruction</tt> constructor with a
845<tt>insertBefore</tt> (default) parameter, the above code becomes:
846<pre>
847Instruction* pi = ...;
848Instruction* newInst = new Instruction(..., pi);
849</pre>
850which is much cleaner, especially if you're creating a lot of
851instructions and adding them to <tt>BasicBlock</tt>s.
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000852 </p>
Joel Stanley753eb712002-09-11 22:32:24 +0000853</p>
Chris Lattner9ebf5162002-09-12 19:08:16 +0000854</ul>
Joel Stanley753eb712002-09-11 22:32:24 +0000855
856<!--_______________________________________________________________________-->
857</ul><h4><a name="schanges_deleting"><hr size=0>Deleting
Chris Lattner4e1f96b2002-09-12 19:06:51 +0000858<tt>Instruction</tt>s</h4><ul>
859
860Deleting an instruction from an existing sequence of instructions that form a <a
861href="#BasicBlock"><tt>BasicBlock</tt></a> is very straightforward. First, you
862must have a pointer to the instruction that you wish to delete. Second, you
863need to obtain the pointer to that instruction's basic block. You use the
864pointer to the basic block to get its list of instructions and then use the
865erase function to remove your instruction.<p>
866
867For example:<p>
868
869<pre>
870 <a href="#Instruction">Instruction</a> *I = .. ;
Chris Lattner7dbf6832002-09-18 05:14:25 +0000871 <a href="#BasicBlock">BasicBlock</a> *BB = I-&gt;getParent();
872 BB-&gt;getInstList().erase(I);
Chris Lattner4e1f96b2002-09-12 19:06:51 +0000873</pre><p>
874
Joel Stanley753eb712002-09-11 22:32:24 +0000875<!--_______________________________________________________________________-->
876</ul><h4><a name="schanges_replacing"><hr size=0>Replacing an
877 <tt>Instruction</tt> with another <tt>Value</tt></h4><ul>
878
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000879<p><i>Replacing individual instructions</i></p>
880<p>
881Including "<a
Chris Lattner7dbf6832002-09-18 05:14:25 +0000882href="/doxygen/BasicBlockUtils_8h-source.html">llvm/Transforms/Utils/BasicBlockUtils.h
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000883</a>" permits use of two very useful replace functions:
884<tt>ReplaceInstWithValue</tt> and <tt>ReplaceInstWithInst</tt>.
Chris Lattnerae7f7592002-09-06 18:31:18 +0000885
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000886<ul>
887
Chris Lattner7dbf6832002-09-18 05:14:25 +0000888<li><tt>ReplaceInstWithValue</tt>
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000889
890<p>This function replaces all uses (within a basic block) of a given
891instruction with a value, and then removes the original instruction.
892The following example illustrates the replacement of the result of a
893particular <tt>AllocaInst</tt> that allocates memory for a single
894integer with an null pointer to an integer.</p>
895
896<pre>
897AllocaInst* instToReplace = ...;
Joel Stanley4b287932002-09-29 17:31:54 +0000898BasicBlock::iterator ii(instToReplace);
899ReplaceInstWithValue(instToReplace-&gt;getParent()-&gt;getInstList(), ii,
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000900 Constant::getNullValue(PointerType::get(Type::IntTy)));
901</pre>
902
Chris Lattner7dbf6832002-09-18 05:14:25 +0000903<li><tt>ReplaceInstWithInst</tt>
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000904
905<p>This function replaces a particular instruction with another
906instruction. The following example illustrates the replacement of one
907<tt>AllocaInst</tt> with another.<p>
908
909<pre>
910AllocaInst* instToReplace = ...;
Joel Stanley4b287932002-09-29 17:31:54 +0000911BasicBlock::iterator ii(instToReplace);
912ReplaceInstWithInst(instToReplace-&gt;getParent()-&gt;getInstList(), ii,
Joel Stanley9dd1ad62002-09-18 03:17:23 +0000913 new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt");
914</pre>
915
916</ul>
917<p><i>Replacing multiple uses of <tt>User</tt>s and
918 <tt>Value</tt>s</i></p>
919
920You can use <tt>Value::replaceAllUsesWith</tt> and
921<tt>User::replaceUsesOfWith</tt> to change more than one use at a
922time. See the doxygen documentation for the <a
923href="/doxygen/classValue.html">Value Class</a> and <a
924href="/doxygen/classUser.html">User Class</a>, respectively, for more
925information.
926
927<!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out:
928include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with:
929ReplaceInstWithValue, ReplaceInstWithInst
Chris Lattnerae7f7592002-09-06 18:31:18 +0000930-->
Chris Lattnerb99344f2002-09-06 16:40:10 +0000931
Chris Lattner9355b472002-09-06 02:50:58 +0000932<!-- *********************************************************************** -->
933</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
934<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Joel Stanley9b96c442002-09-06 21:55:13 +0000935<a name="coreclasses">The Core LLVM Class Hierarchy Reference
Chris Lattner9355b472002-09-06 02:50:58 +0000936</b></font></td></tr></table><ul>
937<!-- *********************************************************************** -->
938
939The Core LLVM classes are the primary means of representing the program being
940inspected or transformed. The core LLVM classes are defined in header files in
941the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
942directory.<p>
943
944
945<!-- ======================================================================= -->
946</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
947<tr><td>&nbsp;</td><td width="100%">&nbsp;
948<font color="#EEEEFF" face="Georgia,Palatino"><b>
949<a name="Value">The <tt>Value</tt> class</a>
950</b></font></td></tr></table><ul>
951
952<tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
953doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
954
955
956The <tt>Value</tt> class is the most important class in LLVM Source base. It
957represents a typed value that may be used (among other things) as an operand to
958an instruction. There are many different types of <tt>Value</tt>s, such as <a
959href="#Constant"><tt>Constant</tt></a>s, <a
960href="#Argument"><tt>Argument</tt></a>s, and even <a
961href="#Instruction"><tt>Instruction</tt></a>s and <a
962href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
963
964A particular <tt>Value</tt> may be used many times in the LLVM representation
965for a program. For example, an incoming argument to a function (represented
966with an instance of the <a href="#Argument">Argument</a> class) is "used" by
967every instruction in the function that references the argument. To keep track
968of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
969href="#User"><tt>User</tt></a>s that is using it (the <a
970href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
971graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
Joel Stanley9b96c442002-09-06 21:55:13 +0000972def-use information in the program, and is accessible through the <tt>use_</tt>*
Chris Lattner9355b472002-09-06 02:50:58 +0000973methods, shown below.<p>
974
975Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
976this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
977method. <a name="#nameWarning">In addition, all LLVM values can be named. The
978"name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
979
980<pre>
981 %<b>foo</b> = add int 1, 2
982</pre>
983
984The name of this instruction is "foo". <b>NOTE</b> that the name of any value
985may be missing (an empty string), so names should <b>ONLY</b> be used for
986debugging (making the source code easier to read, debugging printouts), they
987should not be used to keep track of values or map between them. For this
988purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
989instead.<p>
990
991One important aspect of LLVM is that there is no distinction between an SSA
992variable and the operation that produces it. Because of this, any reference to
993the value produced by an instruction (or the value available as an incoming
994argument, for example) is represented as a direct pointer to the class that
995represents this value. Although this may take some getting used to, it
996simplifies the representation and makes it easier to manipulate.<p>
997
998
999<!-- _______________________________________________________________________ -->
1000</ul><h4><a name="m_Value"><hr size=0>Important Public Members of
1001the <tt>Value</tt> class</h4><ul>
1002
1003<li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
1004 <tt>Value::use_const_iterator</tt>
1005 - Typedef for const_iterator over the use-list<br>
1006 <tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
1007 <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
1008 <tt>use_iterator use_begin()</tt>
1009 - Get an iterator to the start of the use-list.<br>
1010 <tt>use_iterator use_end()</tt>
1011 - Get an iterator to the end of the use-list.<br>
1012 <tt><a href="#User">User</a> *use_back()</tt>
1013 - Returns the last element in the list.<p>
1014
1015These 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>
1016
1017<li><tt><a href="#Type">Type</a> *getType() const</tt><p>
1018This method returns the Type of the Value.
1019
1020<li><tt>bool hasName() const</tt><br>
1021 <tt>std::string getName() const</tt><br>
1022 <tt>void setName(const std::string &amp;Name)</tt><p>
1023
1024This family of methods is used to access and assign a name to a <tt>Value</tt>,
1025be aware of the <a href="#nameWarning">precaution above</a>.<p>
1026
1027
1028<li><tt>void replaceAllUsesWith(Value *V)</tt><p>
1029
1030This method traverses the use list of a <tt>Value</tt> changing all <a
Misha Brukmanc4f5bb02002-09-18 02:21:57 +00001031href="#User"><tt>User</tt>s</a> of the current value to refer to "<tt>V</tt>"
Chris Lattner9355b472002-09-06 02:50:58 +00001032instead. For example, if you detect that an instruction always produces a
1033constant value (for example through constant folding), you can replace all uses
1034of the instruction with the constant like this:<p>
1035
1036<pre>
1037 Inst-&gt;replaceAllUsesWith(ConstVal);
1038</pre><p>
1039
1040
1041
1042<!-- ======================================================================= -->
1043</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1044<tr><td>&nbsp;</td><td width="100%">&nbsp;
1045<font color="#EEEEFF" face="Georgia,Palatino"><b>
1046<a name="User">The <tt>User</tt> class</a>
1047</b></font></td></tr></table><ul>
1048
1049<tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
1050doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
1051Superclass: <a href="#Value"><tt>Value</tt></a><p>
1052
1053
1054The <tt>User</tt> class is the common base class of all LLVM nodes that may
1055refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
1056that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
1057referring to. The <tt>User</tt> class itself is a subclass of
1058<tt>Value</tt>.<p>
1059
1060The operands of a <tt>User</tt> point directly to the LLVM <a
1061href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
1062Single Assignment (SSA) form, there can only be one definition referred to,
1063allowing this direct connection. This connection provides the use-def
1064information in LLVM.<p>
1065
1066<!-- _______________________________________________________________________ -->
1067</ul><h4><a name="m_User"><hr size=0>Important Public Members of
1068the <tt>User</tt> class</h4><ul>
1069
1070The <tt>User</tt> class exposes the operand list in two ways: through an index
1071access interface and through an iterator based interface.<p>
1072
1073<li><tt>Value *getOperand(unsigned i)</tt><br>
1074 <tt>unsigned getNumOperands()</tt><p>
1075
1076These two methods expose the operands of the <tt>User</tt> in a convenient form
1077for direct access.<p>
1078
1079<li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
1080 <tt>User::op_const_iterator</tt>
1081 <tt>use_iterator op_begin()</tt>
1082 - Get an iterator to the start of the operand list.<br>
1083 <tt>use_iterator op_end()</tt>
1084 - Get an iterator to the end of the operand list.<p>
1085
1086Together, these methods make up the iterator based interface to the operands of
1087a <tt>User</tt>.<p>
1088
1089
1090
1091<!-- ======================================================================= -->
1092</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1093<tr><td>&nbsp;</td><td width="100%">&nbsp;
1094<font color="#EEEEFF" face="Georgia,Palatino"><b>
1095<a name="Instruction">The <tt>Instruction</tt> class</a>
1096</b></font></td></tr></table><ul>
1097
1098<tt>#include "<a
1099href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
1100doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
1101Superclasses: <a href="#User"><tt>User</tt></a>, <a
1102href="#Value"><tt>Value</tt></a><p>
1103
1104The <tt>Instruction</tt> class is the common base class for all LLVM
1105instructions. It provides only a few methods, but is a very commonly used
1106class. The primary data tracked by the <tt>Instruction</tt> class itself is the
1107opcode (instruction type) and the parent <a
1108href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
1109into. To represent a specific type of instruction, one of many subclasses of
1110<tt>Instruction</tt> are used.<p>
1111
1112Because the <tt>Instruction</tt> class subclasses the <a
1113href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
1114way as for other <a href="#User"><tt>User</tt></a>s (with the
1115<tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
1116<tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
1117
Chris Lattner17635252002-09-12 17:18:46 +00001118An important file for the <tt>Instruction</tt> class is the
1119<tt>llvm/Instruction.def</tt> file. This file contains some meta-data about the
1120various different types of instructions in LLVM. It describes the enum values
1121that are used as opcodes (for example <tt>Instruction::Add</tt> and
1122<tt>Instruction::SetLE</tt>), as well as the concrete sub-classes of
1123<tt>Instruction</tt> that implement the instruction (for example <tt><a
1124href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a
1125href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, the use of macros in
1126this file confused doxygen, so these enum values don't show up correctly in the
1127<a href="/doxygen/classInstruction.html">doxygen output</a>.<p>
1128
Chris Lattner9355b472002-09-06 02:50:58 +00001129
1130<!-- _______________________________________________________________________ -->
1131</ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
1132the <tt>Instruction</tt> class</h4><ul>
1133
1134<li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
1135
1136Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
1137<tt>Instruction</tt> is embedded into.<p>
1138
Chris Lattnerc3dc2122003-02-26 16:38:15 +00001139<li><tt>bool mayWriteToMemory()</tt><p>
Chris Lattner9355b472002-09-06 02:50:58 +00001140
Chris Lattnerc3dc2122003-02-26 16:38:15 +00001141Returns true if the instruction writes to memory, i.e. it is a <tt>call</tt>,
Chris Lattner9355b472002-09-06 02:50:58 +00001142<tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
1143
1144<li><tt>unsigned getOpcode()</tt><p>
1145
1146Returns the opcode for the <tt>Instruction</tt>.<p>
1147
Chris Lattner17635252002-09-12 17:18:46 +00001148<li><tt><a href="#Instruction">Instruction</a> *clone() const</tt><p>
1149
1150Returns another instance of the specified instruction, identical in all ways to
1151the original except that the instruction has no parent (ie it's not embedded
1152into a <a href="#BasicBlock"><tt>BasicBlock</tt></a>), and it has no name.<p>
1153
1154
1155
Chris Lattner9355b472002-09-06 02:50:58 +00001156<!--
1157
1158\subsection{Subclasses of Instruction :}
1159\begin{itemize}
1160<li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
1161 \begin{itemize}
1162 <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.
1163 \end{itemize}
1164<li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
1165 \begin{itemize}
1166 <li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
1167 <li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
1168 <li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
1169 \end{itemize}
1170
1171<li>PHINode : This represents the PHI instructions in the SSA form.
1172 \begin{itemize}
1173 <li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
1174 <li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
1175 <li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
1176 <li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
1177 <li><tt> void addIncoming(Value *D, BasicBlock *BB)</tt>:
1178 Add an incoming value to the end of the PHI list
1179 <li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
1180 Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
1181 \end{itemize}
1182<li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
1183<li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
1184 \begin{itemize}
1185 <li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
1186 \end{itemize}
1187<li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
1188 \begin{itemize}
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001189 <li><tt>Value * getPointerOperand()</tt>: Returns the Pointer Operand which is typically the 0th operand.
Chris Lattner9355b472002-09-06 02:50:58 +00001190 \end{itemize}
1191<li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
1192 \begin{itemize}
1193 <li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
1194 <li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
1195 <li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
1196 \end{itemize}
1197
1198\end{itemize}
1199
1200-->
1201
1202
1203<!-- ======================================================================= -->
1204</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1205<tr><td>&nbsp;</td><td width="100%">&nbsp;
1206<font color="#EEEEFF" face="Georgia,Palatino"><b>
1207<a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
1208</b></font></td></tr></table><ul>
1209
1210<tt>#include "<a
1211href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
1212doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
1213Superclass: <a href="#Value"><tt>Value</tt></a><p>
1214
1215
1216This class represents a single entry multiple exit section of the code, commonly
1217known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
1218maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
1219the body of the block. Matching the language definition, the last element of
1220this list of instructions is always a terminator instruction (a subclass of the
1221<a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
1222
1223In addition to tracking the list of instructions that make up the block, the
1224<tt>BasicBlock</tt> class also keeps track of the <a
1225href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
1226
1227Note that <tt>BasicBlock</tt>s themselves are <a
1228href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
1229like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
1230<tt>label</tt>.<p>
1231
1232
1233<!-- _______________________________________________________________________ -->
1234</ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
1235the <tt>BasicBlock</tt> class</h4><ul>
1236
1237<li><tt>BasicBlock(const std::string &amp;Name = "", <a
1238href="#Function">Function</a> *Parent = 0)</tt><p>
1239
1240The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
1241insertion into a function. The constructor simply takes a name for the new
1242block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
1243into. If the <tt>Parent</tt> parameter is specified, the new
1244<tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
1245href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
1246manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
1247
1248<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
1249 <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
1250 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1251 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1252
1253These methods and typedefs are forwarding functions that have the same semantics
1254as the standard library methods of the same names. These methods expose the
1255underlying instruction list of a basic block in a way that is easy to
1256manipulate. To get the full complement of container operations (including
1257operations to update the list), you must use the <tt>getInstList()</tt>
1258method.<p>
1259
1260<li><tt>BasicBlock::InstListType &amp;getInstList()</tt><p>
1261
1262This method is used to get access to the underlying container that actually
1263holds the Instructions. This method must be used when there isn't a forwarding
1264function in the <tt>BasicBlock</tt> class for the operation that you would like
1265to perform. Because there are no forwarding functions for "updating"
1266operations, you need to use this if you want to update the contents of a
1267<tt>BasicBlock</tt>.<p>
1268
1269<li><tt><A href="#Function">Function</a> *getParent()</tt><p>
1270
1271Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
1272embedded into, or a null pointer if it is homeless.<p>
1273
1274<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
1275
1276Returns a pointer to the terminator instruction that appears at the end of the
1277<tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
1278instruction in the block is not a terminator, then a null pointer is
1279returned.<p>
1280
1281
1282<!-- ======================================================================= -->
1283</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1284<tr><td>&nbsp;</td><td width="100%">&nbsp;
1285<font color="#EEEEFF" face="Georgia,Palatino"><b>
1286<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
1287</b></font></td></tr></table><ul>
1288
1289<tt>#include "<a
1290href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
1291doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
1292Superclasses: <a href="#User"><tt>User</tt></a>, <a
1293href="#Value"><tt>Value</tt></a><p>
1294
1295Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
1296href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
1297visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
1298Because they are visible at global scope, they are also subject to linking with
1299other globals defined in different translation units. To control the linking
1300process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
1301<tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
1302
1303If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
1304<tt>static</tt> in C), it is not visible to code outside the current translation
1305unit, and does not participate in linking. If it has external linkage, it is
1306visible to external code, and does participate in linking. In addition to
1307linkage information, <tt>GlobalValue</tt>s keep track of which <a
1308href="#Module"><tt>Module</tt></a> they are currently part of.<p>
1309
1310Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
1311their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
1312always a pointer to its contents. This is explained in the LLVM Language
1313Reference Manual.<p>
1314
1315
1316<!-- _______________________________________________________________________ -->
1317</ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
1318the <tt>GlobalValue</tt> class</h4><ul>
1319
1320<li><tt>bool hasInternalLinkage() const</tt><br>
1321 <tt>bool hasExternalLinkage() const</tt><br>
1322 <tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
1323
1324These methods manipulate the linkage characteristics of the
1325<tt>GlobalValue</tt>.<p>
1326
1327<li><tt><a href="#Module">Module</a> *getParent()</tt><p>
1328
1329This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
1330currently embedded into.<p>
1331
1332
1333
1334<!-- ======================================================================= -->
1335</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1336<tr><td>&nbsp;</td><td width="100%">&nbsp;
1337<font color="#EEEEFF" face="Georgia,Palatino"><b>
1338<a name="Function">The <tt>Function</tt> class</a>
1339</b></font></td></tr></table><ul>
1340
1341<tt>#include "<a
1342href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
1343doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
1344Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
1345href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
1346
1347The <tt>Function</tt> class represents a single procedure in LLVM. It is
1348actually one of the more complex classes in the LLVM heirarchy because it must
1349keep track of a large amount of data. The <tt>Function</tt> class keeps track
1350of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
1351href="#Argument"><tt>Argument</tt></a>s, and a <a
1352href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
1353
1354The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
1355used part of <tt>Function</tt> objects. The list imposes an implicit ordering
1356of the blocks in the function, which indicate how the code will be layed out by
1357the backend. Additionally, the first <a
1358href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
1359<tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
1360block. There are no implicit exit nodes, and in fact there may be multiple exit
1361nodes from a single <tt>Function</tt>. If the <a
1362href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
1363the <tt>Function</tt> is actually a function declaration: the actual body of the
1364function hasn't been linked in yet.<p>
1365
1366In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
1367<tt>Function</tt> class also keeps track of the list of formal <a
1368href="#Argument"><tt>Argument</tt></a>s that the function receives. This
1369container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
1370nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
1371the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
1372
1373The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
1374feature that is only used when you have to look up a value by name. Aside from
1375that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
1376make sure that there are not conflicts between the names of <a
1377href="#Instruction"><tt>Instruction</tt></a>s, <a
1378href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
1379href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
1380
1381
1382<!-- _______________________________________________________________________ -->
1383</ul><h4><a name="m_Function"><hr size=0>Important Public Members of
1384the <tt>Function</tt> class</h4><ul>
1385
1386<li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &amp;N = "")</tt><p>
1387
1388Constructor used when you need to create new <tt>Function</tt>s to add the the
1389program. The constructor must specify the type of the function to create and
1390whether or not it should start out with internal or external linkage.<p>
1391
1392<li><tt>bool isExternal()</tt><p>
1393
1394Return whether or not the <tt>Function</tt> has a body defined. If the function
1395is "external", it does not have a body, and thus must be resolved by linking
1396with a function defined in a different translation unit.<p>
1397
1398
1399<li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
1400 <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
1401 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1402 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1403
1404These are forwarding methods that make it easy to access the contents of a
1405<tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
1406list.<p>
1407
1408<li><tt>Function::BasicBlockListType &amp;getBasicBlockList()</tt><p>
1409
1410Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
1411neccesary to use when you need to update the list or perform a complex action
1412that doesn't have a forwarding method.<p>
1413
1414
1415<li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
1416 <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
1417 <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
1418 <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
1419
1420These are forwarding methods that make it easy to access the contents of a
1421<tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
1422
1423<li><tt>Function::ArgumentListType &amp;getArgumentList()</tt><p>
1424
1425Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
1426neccesary to use when you need to update the list or perform a complex action
1427that doesn't have a forwarding method.<p>
1428
1429
1430
1431<li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
1432
1433Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
1434function. Because the entry block for the function is always the first block,
1435this returns the first block of the <tt>Function</tt>.<p>
1436
1437<li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
1438 <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
1439
1440This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
1441and returns the return type of the function, or the <a
1442href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
1443
Chris Lattner9355b472002-09-06 02:50:58 +00001444<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1445
1446Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
Chris Lattner6e6026b2002-11-20 18:36:02 +00001447<tt>Function</tt>.<p>
Chris Lattner9355b472002-09-06 02:50:58 +00001448
1449
1450
1451<!-- ======================================================================= -->
1452</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1453<tr><td>&nbsp;</td><td width="100%">&nbsp;
1454<font color="#EEEEFF" face="Georgia,Palatino"><b>
1455<a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
1456</b></font></td></tr></table><ul>
1457
1458<tt>#include "<a
1459href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
1460doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
1461Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
1462href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
1463
Chris Lattner0377de42002-09-06 14:50:55 +00001464Global variables are represented with the (suprise suprise)
1465<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
1466also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
1467are always referenced by their address (global values must live in memory, so
1468their "name" refers to their address). Global variables may have an initial
1469value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
1470have an initializer, they may be marked as "constant" themselves (indicating
1471that their contents never change at runtime).<p>
Chris Lattner9355b472002-09-06 02:50:58 +00001472
1473
1474<!-- _______________________________________________________________________ -->
Chris Lattner0377de42002-09-06 14:50:55 +00001475</ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
1476<tt>GlobalVariable</tt> class</h4><ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001477
1478<li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
1479isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
1480&amp;Name = "")</tt><p>
1481
Chris Lattner0377de42002-09-06 14:50:55 +00001482Create a new global variable of the specified type. If <tt>isConstant</tt> is
1483true then the global variable will be marked as unchanging for the program, and
1484if <tt>isInternal</tt> is true the resultant global variable will have internal
1485linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
1486
1487
Chris Lattner9355b472002-09-06 02:50:58 +00001488<li><tt>bool isConstant() const</tt><p>
1489
1490Returns true if this is a global variable is known not to be modified at
1491runtime.<p>
1492
Chris Lattner0377de42002-09-06 14:50:55 +00001493
Chris Lattner9355b472002-09-06 02:50:58 +00001494<li><tt>bool hasInitializer()</tt><p>
1495
1496Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
1497
Chris Lattner0377de42002-09-06 14:50:55 +00001498
Chris Lattner9355b472002-09-06 02:50:58 +00001499<li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
1500
Chris Lattner0377de42002-09-06 14:50:55 +00001501Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
1502this method if there is no initializer.<p>
1503
1504
1505<!-- ======================================================================= -->
1506</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1507<tr><td>&nbsp;</td><td width="100%">&nbsp;
1508<font color="#EEEEFF" face="Georgia,Palatino"><b>
1509<a name="Module">The <tt>Module</tt> class</a>
1510</b></font></td></tr></table><ul>
1511
1512<tt>#include "<a
1513href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
1514doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
1515
1516The <tt>Module</tt> class represents the top level structure present in LLVM
1517programs. An LLVM module is effectively either a translation unit of the
1518original program or a combination of several translation units merged by the
1519linker. The <tt>Module</tt> class keeps track of a list of <a
1520href="#Function"><tt>Function</tt></a>s, a list of <a
1521href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
1522href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
1523helpful member functions that try to make common operations easy.<p>
1524
1525
1526<!-- _______________________________________________________________________ -->
1527</ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
1528<tt>Module</tt> class</h4><ul>
1529
1530<li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
1531 <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
1532 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1533 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1534
1535These are forwarding methods that make it easy to access the contents of a
1536<tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
1537list.<p>
1538
1539<li><tt>Module::FunctionListType &amp;getFunctionList()</tt><p>
1540
1541Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
1542neccesary to use when you need to update the list or perform a complex action
1543that doesn't have a forwarding method.<p>
1544
1545<!-- Global Variable -->
1546<hr size=0>
1547
1548<li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
1549 <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
1550 <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
1551 <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
1552
1553These are forwarding methods that make it easy to access the contents of a
1554<tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
1555list.<p>
1556
1557<li><tt>Module::GlobalListType &amp;getGlobalList()</tt><p>
1558
1559Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
1560This is neccesary to use when you need to update the list or perform a complex
1561action that doesn't have a forwarding method.<p>
1562
1563
1564<!-- Symbol table stuff -->
1565<hr size=0>
1566
Chris Lattner0377de42002-09-06 14:50:55 +00001567<li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1568
Chris Lattner6e6026b2002-11-20 18:36:02 +00001569Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for
1570this <tt>Module</tt>.<p>
Chris Lattner0377de42002-09-06 14:50:55 +00001571
1572
1573<!-- Convenience methods -->
1574<hr size=0>
1575
1576<li><tt><a href="#Function">Function</a> *getFunction(const std::string &amp;Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt><p>
1577
1578Look up the specified function in the <tt>Module</tt> <a
1579href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
1580<tt>null</tt>.<p>
1581
1582
1583<li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
1584 &amp;Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
1585
1586Look up the specified function in the <tt>Module</tt> <a
1587href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
1588external declaration for the function and return it.<p>
1589
1590
1591<li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
1592
1593If there is at least one entry in the <a
1594href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
1595href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
1596string.<p>
1597
1598
1599<li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
1600*Ty)</tt><p>
1601
1602Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
1603<tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
1604is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
1605modified.<p>
1606
Chris Lattner9355b472002-09-06 02:50:58 +00001607
1608<!-- ======================================================================= -->
1609</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1610<tr><td>&nbsp;</td><td width="100%">&nbsp;
1611<font color="#EEEEFF" face="Georgia,Palatino"><b>
1612<a name="Constant">The <tt>Constant</tt> class and subclasses</a>
1613</b></font></td></tr></table><ul>
1614
1615Constant represents a base class for different types of constants. It is
1616subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
1617ConstantArray etc for representing the various types of Constants.<p>
1618
1619
1620<!-- _______________________________________________________________________ -->
1621</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1622
1623<li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
1624
1625
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001626<hr>
1627Important Subclasses of Constant<p>
Chris Lattner9355b472002-09-06 02:50:58 +00001628
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001629<ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001630<li>ConstantSInt : This subclass of Constant represents a signed integer constant.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001631<ul>
1632 <li><tt>int64_t getValue() const</tt>: Returns the underlying value of this constant.
1633</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001634<li>ConstantUInt : This class represents an unsigned integer.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001635<ul>
1636 <li><tt>uint64_t getValue() const</tt>: Returns the underlying value of this constant.
1637</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001638<li>ConstantFP : This class represents a floating point constant.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001639<ul>
1640 <li><tt>double getValue() const</tt>: Returns the underlying value of this constant.
1641</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001642<li>ConstantBool : This represents a boolean constant.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001643<ul>
1644 <li><tt>bool getValue() const</tt>: Returns the underlying value of this constant.
1645</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001646<li>ConstantArray : This represents a constant array.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001647<ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001648 <li><tt>const std::vector<Use> &amp;getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001649</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001650<li>ConstantStruct : This represents a constant struct.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001651<ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001652 <li><tt>const std::vector<Use> &amp;getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001653</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001654<li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001655<ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001656<li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001657</ul>
1658</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001659
1660
1661<!-- ======================================================================= -->
1662</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1663<tr><td>&nbsp;</td><td width="100%">&nbsp;
1664<font color="#EEEEFF" face="Georgia,Palatino"><b>
1665<a name="Type">The <tt>Type</tt> class and Derived Types</a>
1666</b></font></td></tr></table><ul>
1667
1668Type as noted earlier is also a subclass of a Value class. Any primitive
1669type (like int, short etc) in LLVM is an instance of Type Class. All
1670other types are instances of subclasses of type like FunctionType,
1671ArrayType etc. DerivedType is the interface for all such dervied types
1672including FunctionType, ArrayType, PointerType, StructType. Types can have
1673names. They can be recursive (StructType). There exists exactly one instance
1674of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
1675
1676<!-- _______________________________________________________________________ -->
1677</ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1678
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001679<li><tt>PrimitiveID getPrimitiveID() const</tt>: Returns the base type of the type.
1680<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.
1681<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.
1682<li><tt> bool isInteger() const</tt>: Equilivent to isSigned() || isUnsigned(), but with only a single virtual function invocation.
1683<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.
Chris Lattner9355b472002-09-06 02:50:58 +00001684
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001685<li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two floating point types.
1686<li><tt>bool isRecursive() const</tt>: Returns rue if the type graph contains a cycle.
Chris Lattner9355b472002-09-06 02:50:58 +00001687<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.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001688<li><tt>bool isPrimitiveType() const</tt>: Returns true if it is a primitive type.
1689<li><tt>bool isDerivedType() const</tt>: Returns true if it is a derived type.
Chris Lattner9355b472002-09-06 02:50:58 +00001690<li><tt>const Type * getContainedType (unsigned i) const</tt>:
1691This 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.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001692<li><tt>unsigned getNumContainedTypes() const</tt>: Return the number of types in the derived type.
Chris Lattner9355b472002-09-06 02:50:58 +00001693
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001694<p>
Chris Lattner9355b472002-09-06 02:50:58 +00001695
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001696<hr>
1697Derived Types<p>
Chris Lattner9355b472002-09-06 02:50:58 +00001698
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001699<ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001700<li>SequentialType : This is subclassed by ArrayType and PointerType
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001701<ul>
1702 <li><tt>const Type * getElementType() const</tt>: Returns the type of each of the elements in the sequential type.
1703</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001704<li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001705<ul>
1706 <li><tt>unsigned getNumElements() const</tt>: Returns the number of elements in the array.
1707</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001708<li>PointerType : Subclass of SequentialType for pointer types.
1709<li>StructType : subclass of DerivedTypes for struct types
1710<li>FunctionType : subclass of DerivedTypes for function types.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001711
1712<ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001713
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001714 <li><tt>bool isVarArg() const</tt>: Returns true if its a vararg function
1715 <li><tt> const Type * getReturnType() const</tt>: Returns the return type of the function.
1716 <li><tt> const ParamTypes &amp;getParamTypes() const</tt>: Returns a vector of parameter types.
Chris Lattner9355b472002-09-06 02:50:58 +00001717 <li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
Chris Lattnerc75ff9a2002-10-01 23:17:09 +00001718 <li><tt> const unsigned getNumParams() const</tt>: Returns the number of formal parameters.
1719</ul>
1720</ul>
Chris Lattner9355b472002-09-06 02:50:58 +00001721
1722
1723
1724
1725<!-- ======================================================================= -->
1726</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1727<tr><td>&nbsp;</td><td width="100%">&nbsp;
1728<font color="#EEEEFF" face="Georgia,Palatino"><b>
1729<a name="Argument">The <tt>Argument</tt> class</a>
1730</b></font></td></tr></table><ul>
1731
1732This subclass of Value defines the interface for incoming formal arguments to a
1733function. A Function maitanis a list of its formal arguments. An argument has a
1734pointer to the parent Function.
1735
1736
1737
1738
1739<!-- *********************************************************************** -->
1740</ul>
1741<!-- *********************************************************************** -->
1742
1743<hr><font size-1>
1744<address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
1745<a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1746<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
1747<!-- hhmts start -->
Chris Lattnerc3dc2122003-02-26 16:38:15 +00001748Last modified: Mon Feb 24 14:45:19 CST 2003
Chris Lattner9355b472002-09-06 02:50:58 +00001749<!-- hhmts end -->
1750</font></body></html>