Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" |
| 2 | "http://www.w3.org/TR/html4/strict.dtd"> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 3 | <html> |
| 4 | <head> |
| 5 | <title>LLVM Programmer's Manual</title> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 6 | <link rel="stylesheet" href="llvm.css" type="text/css"> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 7 | </head> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 8 | <body> |
| 9 | |
| 10 | <div class="doc_title"> |
| 11 | LLVM Programmer's Manual |
| 12 | </div> |
| 13 | |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 14 | <ol> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 15 | <li><a href="#introduction">Introduction</a></li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 16 | <li><a href="#general">General Information</a> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 17 | <ul> |
| 18 | <li><a href="#stl">The C++ Standard Template Library</a><!-- |
Chris Lattner | 986e0c9 | 2002-09-22 19:38:40 +0000 | [diff] [blame] | 19 | <li>The <tt>-time-passes</tt> option |
| 20 | <li>How to use the LLVM Makefile system |
| 21 | <li>How to write a regression test |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 22 | --> </li> |
Chris Lattner | 84b7f8d | 2003-08-01 22:20:59 +0000 | [diff] [blame] | 23 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 24 | </li> |
| 25 | <li><a href="#apis">Important and useful LLVM APIs</a> |
| 26 | <ul> |
| 27 | <li><a href="#isa">The <tt>isa<></tt>, <tt>cast<></tt> |
| 28 | and <tt>dyn_cast<></tt> templates</a> </li> |
| 29 | <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> |
| 30 | option</a> |
| 31 | <ul> |
| 32 | <li><a href="#DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt> |
| 33 | and the <tt>-debug-only</tt> option</a> </li> |
| 34 | </ul> |
| 35 | </li> |
| 36 | <li><a href="#Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt> |
| 37 | option</a><!-- |
Chris Lattner | 986e0c9 | 2002-09-22 19:38:40 +0000 | [diff] [blame] | 38 | <li>The <tt>InstVisitor</tt> template |
| 39 | <li>The general graph API |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 40 | --> </li> |
| 41 | </ul> |
| 42 | </li> |
Chris Lattner | ae7f759 | 2002-09-06 18:31:18 +0000 | [diff] [blame] | 43 | <li><a href="#common">Helpful Hints for Common Operations</a> |
Chris Lattner | ae7f759 | 2002-09-06 18:31:18 +0000 | [diff] [blame] | 44 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 45 | <li><a href="#inspection">Basic Inspection and Traversal Routines</a> |
| 46 | <ul> |
| 47 | <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s |
| 48 | in a <tt>Function</tt></a> </li> |
| 49 | <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s |
| 50 | in a <tt>BasicBlock</tt></a> </li> |
| 51 | <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s |
| 52 | in a <tt>Function</tt></a> </li> |
| 53 | <li><a href="#iterate_convert">Turning an iterator into a |
| 54 | class pointer</a> </li> |
| 55 | <li><a href="#iterate_complex">Finding call sites: a more |
| 56 | complex example</a> </li> |
| 57 | <li><a href="#calls_and_invokes">Treating calls and invokes |
| 58 | the same way</a> </li> |
| 59 | <li><a href="#iterate_chains">Iterating over def-use & |
| 60 | use-def chains</a> </li> |
| 61 | </ul> |
| 62 | </li> |
| 63 | <li><a href="#simplechanges">Making simple changes</a> |
| 64 | <ul> |
| 65 | <li><a href="#schanges_creating">Creating and inserting new |
| 66 | <tt>Instruction</tt>s</a> </li> |
| 67 | <li><a href="#schanges_deleting">Deleting <tt>Instruction</tt>s</a> </li> |
| 68 | <li><a href="#schanges_replacing">Replacing an <tt>Instruction</tt> |
| 69 | with another <tt>Value</tt></a> </li> |
| 70 | </ul> |
Chris Lattner | ae7f759 | 2002-09-06 18:31:18 +0000 | [diff] [blame] | 71 | <!-- |
| 72 | <li>Working with the Control Flow Graph |
| 73 | <ul> |
| 74 | <li>Accessing predecessors and successors of a <tt>BasicBlock</tt> |
| 75 | <li> |
| 76 | <li> |
| 77 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 78 | --> </li> |
| 79 | </ul> |
| 80 | </li> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 81 | <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 82 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 83 | <li><a href="#Value">The <tt>Value</tt> class</a> |
| 84 | <ul> |
| 85 | <li><a href="#User">The <tt>User</tt> class</a> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 86 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 87 | <li><a href="#Instruction">The <tt>Instruction</tt> class</a> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 88 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 89 | <li><a href="#GetElementPtrInst">The <tt>GetElementPtrInst</tt> |
| 90 | class</a></li> |
| 91 | </ul></li> |
| 92 | <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a> |
| 93 | <ul> |
| 94 | <li><a href="#BasicBlock">The <tt>BasicBlock</tt>class</a></li> |
| 95 | <li><a href="#Function">The <tt>Function</tt> class</a></li> |
| 96 | <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> |
| 97 | class</a></li> |
| 98 | </ul></li> |
| 99 | <li><a href="#Module">The <tt>Module</tt> class</a></li> |
| 100 | <li><a href="#Constant">The <tt>Constant</tt> class</a> |
| 101 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 102 | <li> <br> |
| 103 | </li> |
| 104 | <li> <br> |
| 105 | </li> |
| 106 | </ul> |
| 107 | </li> |
| 108 | </ul> |
| 109 | </li> |
| 110 | <li><a href="#Type">The <tt>Type</tt> class</a> </li> |
| 111 | <li><a href="#Argument">The <tt>Argument</tt> class</a> </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 112 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 113 | </li> |
| 114 | <li>The <tt>SymbolTable</tt> class </li> |
| 115 | <li>The <tt>ilist</tt> and <tt>iplist</tt> classes |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 116 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 117 | <li>Creating, inserting, moving and deleting from LLVM lists </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 118 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 119 | </li> |
| 120 | <li>Important iterator invalidation semantics to be aware of </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 121 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 122 | </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 123 | </ol> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 124 | |
| 125 | <div class="doc_text"> |
| 126 | <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>, |
| 127 | <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>, and <a |
| 128 | href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b></p> |
| 129 | </div> |
| 130 | |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 131 | <!-- *********************************************************************** --> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 132 | <div class="doc_section"> |
| 133 | <a name="introduction">Introduction </a> |
| 134 | </div> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 135 | <!-- *********************************************************************** --> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 136 | |
| 137 | <div class="doc_text"> |
| 138 | |
| 139 | <p>This document is meant to highlight some of the important classes and |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 140 | interfaces available in the LLVM source-base. This manual is not |
| 141 | intended to explain what LLVM is, how it works, and what LLVM code looks |
| 142 | like. It assumes that you know the basics of LLVM and are interested |
| 143 | in writing transformations or otherwise analyzing or manipulating the |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 144 | code.</p> |
| 145 | |
| 146 | <p>This document should get you oriented so that you can find your |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 147 | way in the continuously growing source code that makes up the LLVM |
| 148 | infrastructure. Note that this manual is not intended to serve as a |
| 149 | replacement for reading the source code, so if you think there should be |
| 150 | a method in one of these classes to do something, but it's not listed, |
| 151 | check the source. Links to the <a href="/doxygen/">doxygen</a> sources |
| 152 | are provided to make this as easy as possible.</p> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 153 | |
| 154 | <p>The first section of this document describes general information that is |
| 155 | useful to know when working in the LLVM infrastructure, and the second describes |
| 156 | the Core LLVM classes. In the future this manual will be extended with |
| 157 | information describing how to use extension libraries, such as dominator |
| 158 | information, CFG traversal routines, and useful utilities like the <tt><a |
| 159 | href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.</p> |
| 160 | |
| 161 | </div> |
| 162 | |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 163 | <!-- *********************************************************************** --> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 164 | <div class="doc_section"> |
| 165 | <a name="general">General Information</a> |
| 166 | </div> |
| 167 | <!-- *********************************************************************** --> |
| 168 | |
| 169 | <div class="doc_text"> |
| 170 | |
| 171 | <p>This section contains general information that is useful if you are working |
| 172 | in the LLVM source-base, but that isn't specific to any particular API.</p> |
| 173 | |
| 174 | </div> |
| 175 | |
| 176 | <!-- ======================================================================= --> |
| 177 | <div class="doc_subsection"> |
| 178 | <a name="stl">The C++ Standard Template Library</a> |
| 179 | </div> |
| 180 | |
| 181 | <div class="doc_text"> |
| 182 | |
| 183 | <p>LLVM makes heavy use of the C++ Standard Template Library (STL), |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 184 | perhaps much more than you are used to, or have seen before. Because of |
| 185 | this, you might want to do a little background reading in the |
| 186 | techniques used and capabilities of the library. There are many good |
| 187 | pages that discuss the STL, and several books on the subject that you |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 188 | can get, so it will not be discussed in this document.</p> |
| 189 | |
| 190 | <p>Here are some useful links:</p> |
| 191 | |
| 192 | <ol> |
| 193 | |
| 194 | <li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++ Library |
| 195 | reference</a> - an excellent reference for the STL and other parts of the |
| 196 | standard C++ library.</li> |
| 197 | |
| 198 | <li><a href="http://www.tempest-sw.com/cpp/">C++ In a Nutshell</a> - This is an |
| 199 | O'Reilly book in the making. It has a decent <a |
| 200 | href="http://www.tempest-sw.com/cpp/ch13-libref.html">Standard Library |
| 201 | Reference</a> that rivals Dinkumware's, and is actually free until the book is |
| 202 | published.</li> |
| 203 | |
| 204 | <li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked |
| 205 | Questions</a></li> |
| 206 | |
| 207 | <li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> - |
| 208 | Contains a useful <a |
| 209 | href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the |
| 210 | STL</a>.</li> |
| 211 | |
| 212 | <li><a href="http://www.research.att.com/%7Ebs/C++.html">Bjarne Stroustrup's C++ |
| 213 | Page</a></li> |
| 214 | |
| 215 | </ol> |
| 216 | |
| 217 | <p>You are also encouraged to take a look at the <a |
| 218 | href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how |
| 219 | to write maintainable code more than where to put your curly braces.</p> |
| 220 | |
| 221 | </div> |
| 222 | |
| 223 | <!-- ======================================================================= --> |
| 224 | <div class="doc_subsection"> |
| 225 | <a name="stl">Other useful references</a> |
| 226 | </div> |
| 227 | |
| 228 | <div class="doc_text"> |
| 229 | |
| 230 | <p>LLVM is currently using CVS as its source versioning system. You may find |
| 231 | this reference handy:</p> |
| 232 | |
| 233 | <ol> |
| 234 | <li><a href="http://www.psc.edu/%7Esemke/cvs_branches.html">CVS |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 235 | Branch and Tag Primer</a></li> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 236 | </ol> |
| 237 | |
| 238 | </div> |
| 239 | |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 240 | <!-- *********************************************************************** --> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 241 | <div class="doc_section"> |
| 242 | <a name="apis">Important and useful LLVM APIs</a> |
| 243 | </div> |
| 244 | <!-- *********************************************************************** --> |
| 245 | |
| 246 | <div class="doc_text"> |
| 247 | |
| 248 | <p>Here we highlight some LLVM APIs that are generally useful and good to |
| 249 | know about when writing transformations.</p> |
| 250 | |
| 251 | </div> |
| 252 | |
| 253 | <!-- ======================================================================= --> |
| 254 | <div class="doc_subsection"> |
| 255 | <a name="isa">The isa<>, cast<> and dyn_cast<> templates</a> |
| 256 | </div> |
| 257 | |
| 258 | <div class="doc_text"> |
| 259 | |
| 260 | <p>The LLVM source-base makes extensive use of a custom form of RTTI. |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 261 | These templates have many similarities to the C++ <tt>dynamic_cast<></tt> |
| 262 | operator, but they don't have some drawbacks (primarily stemming from |
| 263 | the fact that <tt>dynamic_cast<></tt> only works on classes that |
| 264 | have a v-table). Because they are used so often, you must know what they |
| 265 | do and how they work. All of these templates are defined in the <a |
| 266 | href="/doxygen/Casting_8h-source.html"><tt>Support/Casting.h</tt></a> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 267 | file (note that you very rarely have to include this file directly).</p> |
| 268 | |
| 269 | <dl> |
| 270 | <dt><tt>isa<></tt>: </dt> |
| 271 | |
| 272 | <dd>The <tt>isa<></tt> operator works exactly like the Java |
| 273 | "<tt>instanceof</tt>" operator. It returns true or false depending on whether |
| 274 | a reference or pointer points to an instance of the specified class. This can |
| 275 | be very useful for constraint checking of various sorts (example below).</dd> |
| 276 | |
| 277 | <dt><tt>cast<></tt>: </dt> |
| 278 | |
| 279 | <dd>The <tt>cast<></tt> operator is a "checked cast" operation. It |
| 280 | converts a pointer or reference from a base class to a derived cast, causing |
| 281 | an assertion failure if it is not really an instance of the right type. This |
| 282 | should be used in cases where you have some information that makes you believe |
| 283 | that something is of the right type. An example of the <tt>isa<></tt> |
| 284 | and <tt>cast<></tt> template is: |
| 285 | |
| 286 | <pre>static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const |
| 287 | Loop *L) {<br> if (isa<<a href="#Constant">Constant</a>>(V) || isa<<a |
| 288 | href="#Argument">Argument</a>>(V) || isa<<a |
| 289 | href="#GlobalValue">GlobalValue</a>>(V))<br> return true;<br><br> <i>// |
| 290 | Otherwise, it must be an instruction...</i><br> return |
| 291 | !L->contains(cast<<a |
| 292 | href="#Instruction">Instruction</a>>(V)->getParent());<br></pre> |
| 293 | |
| 294 | <p>Note that you should <b>not</b> use an <tt>isa<></tt> test followed |
| 295 | by a <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt> |
| 296 | operator.</p> |
| 297 | |
| 298 | </dd> |
| 299 | |
| 300 | <dt><tt>dyn_cast<></tt>:</dt> |
| 301 | |
| 302 | <dd>The <tt>dyn_cast<></tt> operator is a "checking cast" operation. It |
| 303 | checks to see if the operand is of the specified type, and if so, returns a |
| 304 | pointer to it (this operator does not work with references). If the operand is |
| 305 | not of the correct type, a null pointer is returned. Thus, this works very |
| 306 | much like the <tt>dynamic_cast</tt> operator in C++, and should be used in the |
| 307 | same circumstances. Typically, the <tt>dyn_cast<></tt> operator is used |
| 308 | in an <tt>if</tt> statement or some other flow control statement like this: |
| 309 | |
| 310 | <pre> if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a |
| 311 | href="#AllocationInst">AllocationInst</a>>(Val)) {<br> ...<br> }<br></pre> |
| 312 | |
| 313 | <p> This form of the <tt>if</tt> statement effectively combines together a |
| 314 | call to <tt>isa<></tt> and a call to <tt>cast<></tt> into one |
| 315 | statement, which is very convenient.</p> |
| 316 | |
| 317 | <p> Another common example is:</p> |
| 318 | |
| 319 | <pre> <i>// Loop over all of the phi nodes in a basic block</i><br> |
| 320 | BasicBlock::iterator BBI = BB->begin();<br> for (; <a |
| 321 | href="#PhiNode">PHINode</a> *PN = dyn_cast<<a |
| 322 | href="#PHINode">PHINode</a>>(BBI); ++BBI)<br> cerr << *PN;<br></pre> |
| 323 | |
| 324 | <p>Note that the <tt>dyn_cast<></tt> operator, like C++'s |
| 325 | <tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused. |
| 326 | In particular you should not use big chained <tt>if/then/else</tt> blocks to |
| 327 | check for lots of different variants of classes. If you find yourself |
| 328 | wanting to do this, it is much cleaner and more efficient to use the |
| 329 | InstVisitor class to dispatch over the instruction type directly.</p> |
| 330 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 331 | </dd> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 332 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 333 | <dt><tt>cast_or_null<></tt>: </dt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 334 | |
| 335 | <dd>The <tt>cast_or_null<></tt> operator works just like the |
| 336 | <tt>cast<></tt> operator, except that it allows for a null pointer as |
| 337 | an argument (which it then propagates). This can sometimes be useful, |
| 338 | allowing you to combine several null checks into one.</dd> |
| 339 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 340 | <dt><tt>dyn_cast_or_null<></tt>: </dt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 341 | |
| 342 | <dd>The <tt>dyn_cast_or_null<></tt> operator works just like the |
| 343 | <tt>dyn_cast<></tt> operator, except that it allows for a null pointer |
| 344 | as an argument (which it then propagates). This can sometimes be useful, |
| 345 | allowing you to combine several null checks into one.</dd> |
| 346 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 347 | </dl> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 348 | |
| 349 | <p>These five templates can be used with any classes, whether they have a |
| 350 | v-table or not. To add support for these templates, you simply need to add |
| 351 | <tt>classof</tt> static methods to the class you are interested casting |
| 352 | to. Describing this is currently outside the scope of this document, but there |
| 353 | are lots of examples in the LLVM source base.</p> |
| 354 | |
| 355 | </div> |
| 356 | |
| 357 | <!-- ======================================================================= --> |
| 358 | <div class="doc_subsection"> |
| 359 | <a name="DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> option</a> |
| 360 | </div> |
| 361 | |
| 362 | <div class="doc_text"> |
| 363 | |
| 364 | <p>Often when working on your pass you will put a bunch of debugging printouts |
| 365 | and other code into your pass. After you get it working, you want to remove |
| 366 | it... but you may need it again in the future (to work out new bugs that you run |
| 367 | across).</p> |
| 368 | |
| 369 | <p> Naturally, because of this, you don't want to delete the debug printouts, |
| 370 | but you don't want them to always be noisy. A standard compromise is to comment |
| 371 | them out, allowing you to enable them if you need them in the future.</p> |
| 372 | |
| 373 | <p>The "<tt><a href="/doxygen/Debug_8h-source.html">Support/Debug.h</a></tt>" |
| 374 | file provides a macro named <tt>DEBUG()</tt> that is a much nicer solution to |
| 375 | this problem. Basically, you can put arbitrary code into the argument of the |
| 376 | <tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other |
| 377 | tool) is run with the '<tt>-debug</tt>' command line argument:</p> |
| 378 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 379 | <pre> ... <br> DEBUG(std::cerr << "I am here!\n");<br> ...<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 380 | |
| 381 | <p>Then you can run your pass like this:</p> |
| 382 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 383 | <pre> $ opt < a.bc > /dev/null -mypass<br> <no output><br> $ opt < a.bc > /dev/null -mypass -debug<br> I am here!<br> $<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 384 | |
| 385 | <p>Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you |
| 386 | to not have to create "yet another" command line option for the debug output for |
| 387 | your pass. Note that <tt>DEBUG()</tt> macros are disabled for optimized builds, |
| 388 | so they do not cause a performance impact at all (for the same reason, they |
| 389 | should also not contain side-effects!).</p> |
| 390 | |
| 391 | <p>One additional nice thing about the <tt>DEBUG()</tt> macro is that you can |
| 392 | enable or disable it directly in gdb. Just use "<tt>set DebugFlag=0</tt>" or |
| 393 | "<tt>set DebugFlag=1</tt>" from the gdb if the program is running. If the |
| 394 | program hasn't been started yet, you can always just run it with |
| 395 | <tt>-debug</tt>.</p> |
| 396 | |
| 397 | </div> |
| 398 | |
| 399 | <!-- _______________________________________________________________________ --> |
| 400 | <div class="doc_subsubsection"> |
| 401 | <a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE()</tt> and |
| 402 | the <tt>-debug-only</tt> option</a> |
| 403 | </div> |
| 404 | |
| 405 | <div class="doc_text"> |
| 406 | |
| 407 | <p>Sometimes you may find yourself in a situation where enabling <tt>-debug</tt> |
| 408 | just turns on <b>too much</b> information (such as when working on the code |
| 409 | generator). If you want to enable debug information with more fine-grained |
| 410 | control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only |
| 411 | option as follows:</p> |
| 412 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 413 | <pre> ...<br> DEBUG(std::cerr << "No debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE "foo"<br> DEBUG(std::cerr << "'foo' debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE "bar"<br> DEBUG(std::cerr << "'bar' debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE ""<br> DEBUG(std::cerr << "No debug type (2)\n");<br> ...<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 414 | |
| 415 | <p>Then you can run your pass like this:</p> |
| 416 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 417 | <pre> $ opt < a.bc > /dev/null -mypass<br> <no output><br> $ opt < a.bc > /dev/null -mypass -debug<br> No debug type<br> 'foo' debug type<br> 'bar' debug type<br> No debug type (2)<br> $ opt < a.bc > /dev/null -mypass -debug-only=foo<br> 'foo' debug type<br> $ opt < a.bc > /dev/null -mypass -debug-only=bar<br> 'bar' debug type<br> $<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 418 | |
| 419 | <p>Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of |
| 420 | a file, to specify the debug type for the entire module (if you do this before |
| 421 | you <tt>#include "Support/Debug.h"</tt>, you don't have to insert the ugly |
| 422 | <tt>#undef</tt>'s). Also, you should use names more meaningful than "foo" and |
| 423 | "bar", because there is no system in place to ensure that names do not |
| 424 | conflict. If two different modules use the same string, they will all be turned |
| 425 | on when the name is specified. This allows, for example, all debug information |
| 426 | for instruction scheduling to be enabled with <tt>-debug-type=InstrSched</tt>, |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 427 | even if the source lives in multiple files.</p> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 428 | |
| 429 | </div> |
| 430 | |
| 431 | <!-- ======================================================================= --> |
| 432 | <div class="doc_subsection"> |
| 433 | <a name="Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt> |
| 434 | option</a> |
| 435 | </div> |
| 436 | |
| 437 | <div class="doc_text"> |
| 438 | |
| 439 | <p>The "<tt><a |
| 440 | href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>" file |
| 441 | provides a template named <tt>Statistic</tt> that is used as a unified way to |
| 442 | keep track of what the LLVM compiler is doing and how effective various |
| 443 | optimizations are. It is useful to see what optimizations are contributing to |
| 444 | making a particular program run faster.</p> |
| 445 | |
| 446 | <p>Often you may run your pass on some big program, and you're interested to see |
| 447 | how many times it makes a certain transformation. Although you can do this with |
| 448 | hand inspection, or some ad-hoc method, this is a real pain and not very useful |
| 449 | for big programs. Using the <tt>Statistic</tt> template makes it very easy to |
| 450 | keep track of this information, and the calculated information is presented in a |
| 451 | uniform manner with the rest of the passes being executed.</p> |
| 452 | |
| 453 | <p>There are many examples of <tt>Statistic</tt> uses, but the basics of using |
| 454 | it are as follows:</p> |
| 455 | |
| 456 | <ol> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 457 | <li>Define your statistic like this: |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 458 | <pre>static Statistic<> NumXForms("mypassname", "The # of times I did stuff");<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 459 | |
| 460 | <p>The <tt>Statistic</tt> template can emulate just about any data-type, |
| 461 | but if you do not specify a template argument, it defaults to acting like |
| 462 | an unsigned int counter (this is usually what you want).</p></li> |
| 463 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 464 | <li>Whenever you make a transformation, bump the counter: |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 465 | <pre> ++NumXForms; // I did stuff<br></pre> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 466 | </li> |
| 467 | </ol> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 468 | |
| 469 | <p>That's all you have to do. To get '<tt>opt</tt>' to print out the |
| 470 | statistics gathered, use the '<tt>-stats</tt>' option:</p> |
| 471 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 472 | <pre> $ opt -stats -mypassname < program.bc > /dev/null<br> ... statistic output ...<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 473 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 474 | <p> When running <tt>gccas</tt> on a C file from the SPEC benchmark |
| 475 | suite, it gives a report that looks like this:</p> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 476 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 477 | <pre> 7646 bytecodewriter - Number of normal instructions<br> 725 bytecodewriter - Number of oversized instructions<br> 129996 bytecodewriter - Number of bytecode bytes written<br> 2817 raise - Number of insts DCEd or constprop'd<br> 3213 raise - Number of cast-of-self removed<br> 5046 raise - Number of expression trees converted<br> 75 raise - Number of other getelementptr's formed<br> 138 raise - Number of load/store peepholes<br> 42 deadtypeelim - Number of unused typenames removed from symtab<br> 392 funcresolve - Number of varargs functions resolved<br> 27 globaldce - Number of global variables removed<br> 2 adce - Number of basic blocks removed<br> 134 cee - Number of branches revectored<br> 49 cee - Number of setcc instruction eliminated<br> 532 gcse - Number of loads removed<br> 2919 gcse - Number of instructions removed<br> 86 indvars - Number of canonical indvars added<br> 87 indvars - Number of aux indvars removed<br> 25 instcombine - Number of dead inst eliminate<br> 434 instcombine - Number of insts combined<br> 248 licm - Number of load insts hoisted<br> 1298 licm - Number of insts hoisted to a loop pre-header<br> 3 licm - Number of insts hoisted to multiple loop preds (bad, no loop pre-header)<br> 75 mem2reg - Number of alloca's promoted<br> 1444 cfgsimplify - Number of blocks simplified<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 478 | |
| 479 | <p>Obviously, with so many optimizations, having a unified framework for this |
| 480 | stuff is very nice. Making your pass fit well into the framework makes it more |
| 481 | maintainable and useful.</p> |
| 482 | |
| 483 | </div> |
| 484 | |
| 485 | <!-- *********************************************************************** --> |
| 486 | <div class="doc_section"> |
| 487 | <a name="common">Helpful Hints for Common Operations</a> |
| 488 | </div> |
| 489 | <!-- *********************************************************************** --> |
| 490 | |
| 491 | <div class="doc_text"> |
| 492 | |
| 493 | <p>This section describes how to perform some very simple transformations of |
| 494 | LLVM code. This is meant to give examples of common idioms used, showing the |
| 495 | practical side of LLVM transformations. <p> Because this is a "how-to" section, |
| 496 | you should also read about the main classes that you will be working with. The |
| 497 | <a href="#coreclasses">Core LLVM Class Hierarchy Reference</a> contains details |
| 498 | and descriptions of the main classes that you should know about.</p> |
| 499 | |
| 500 | </div> |
| 501 | |
| 502 | <!-- NOTE: this section should be heavy on example code --> |
| 503 | <!-- ======================================================================= --> |
| 504 | <div class="doc_subsection"> |
| 505 | <a name="inspection">Basic Inspection and Traversal Routines</a> |
| 506 | </div> |
| 507 | |
| 508 | <div class="doc_text"> |
| 509 | |
| 510 | <p>The LLVM compiler infrastructure have many different data structures that may |
| 511 | be traversed. Following the example of the C++ standard template library, the |
| 512 | techniques used to traverse these various data structures are all basically the |
| 513 | same. For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or |
| 514 | method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt> |
| 515 | function returns an iterator pointing to one past the last valid element of the |
| 516 | sequence, and there is some <tt>XXXiterator</tt> data type that is common |
| 517 | between the two operations.</p> |
| 518 | |
| 519 | <p>Because the pattern for iteration is common across many different aspects of |
| 520 | the program representation, the standard template library algorithms may be used |
| 521 | on them, and it is easier to remember how to iterate. First we show a few common |
| 522 | examples of the data structures that need to be traversed. Other data |
| 523 | structures are traversed in very similar ways.</p> |
| 524 | |
| 525 | </div> |
| 526 | |
| 527 | <!-- _______________________________________________________________________ --> |
| 528 | <div class="subsubsection"> |
| 529 | <a name="iterate_function">Iterating over the </a><a |
| 530 | href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a |
| 531 | href="#Function"><tt>Function</tt></a> |
| 532 | </div> |
| 533 | |
| 534 | <div class="doc_text"> |
| 535 | |
| 536 | <p>It's quite common to have a <tt>Function</tt> instance that you'd like to |
| 537 | transform in some way; in particular, you'd like to manipulate its |
| 538 | <tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over all of |
| 539 | the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>. The following is |
| 540 | an example that prints the name of a <tt>BasicBlock</tt> and the number of |
| 541 | <tt>Instruction</tt>s it contains:</p> |
| 542 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 543 | <pre> // func is a pointer to a Function instance<br> for (Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {<br><br> // print out the name of the basic block if it has one, and then the<br> // number of instructions that it contains<br><br> cerr << "Basic block (name=" << i->getName() << ") has " <br> << i->size() << " instructions.\n";<br> }<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 544 | |
| 545 | <p>Note that i can be used as if it were a pointer for the purposes of |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 546 | invoking member functions of the <tt>Instruction</tt> class. This is |
| 547 | because the indirection operator is overloaded for the iterator |
Chris Lattner | 7496ec5 | 2003-08-05 22:54:23 +0000 | [diff] [blame] | 548 | classes. In the above code, the expression <tt>i->size()</tt> is |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 549 | exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.</p> |
| 550 | |
| 551 | </div> |
| 552 | |
| 553 | <!-- _______________________________________________________________________ --> |
| 554 | <div class="subsubsection"> |
| 555 | <a name="iterate_basicblock">Iterating over the </a><a |
| 556 | href="#Instruction"><tt>Instruction</tt></a>s in a <a |
| 557 | href="#BasicBlock"><tt>BasicBlock</tt></a> |
| 558 | </div> |
| 559 | |
| 560 | <div class="doc_text"> |
| 561 | |
| 562 | <p>Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, it's |
| 563 | easy to iterate over the individual instructions that make up |
| 564 | <tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in |
| 565 | a <tt>BasicBlock</tt>:</p> |
| 566 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 567 | <pre> // blk is a pointer to a BasicBlock instance<br> for (BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)<br> // the next statement works since operator<<(ostream&,...) <br> // is overloaded for Instruction&<br> cerr << *i << "\n";<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 568 | |
| 569 | <p>However, this isn't really the best way to print out the contents of a |
| 570 | <tt>BasicBlock</tt>! Since the ostream operators are overloaded for virtually |
| 571 | anything you'll care about, you could have just invoked the print routine on the |
| 572 | basic block itself: <tt>cerr << *blk << "\n";</tt>.</p> |
| 573 | |
| 574 | <p>Note that currently operator<< is implemented for <tt>Value*</tt>, so |
| 575 | it will print out the contents of the pointer, instead of the pointer value you |
| 576 | might expect. This is a deprecated interface that will be removed in the |
| 577 | future, so it's best not to depend on it. To print out the pointer value for |
| 578 | now, you must cast to <tt>void*</tt>.</p> |
| 579 | |
| 580 | </div> |
| 581 | |
| 582 | <!-- _______________________________________________________________________ --> |
| 583 | <div class="subsubsection"> |
| 584 | <a name="iterate_institer">Iterating over the </a><a |
| 585 | href="#Instruction"><tt>Instruction</tt></a>s in a <a |
| 586 | href="#Function"><tt>Function</tt></a> |
| 587 | </div> |
| 588 | |
| 589 | <div class="doc_text"> |
| 590 | |
| 591 | <p>If you're finding that you commonly iterate over a <tt>Function</tt>'s |
| 592 | <tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s <tt>Instruction</tt>s, |
| 593 | <tt>InstIterator</tt> should be used instead. You'll need to include <a |
| 594 | href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>, |
| 595 | and then instantiate <tt>InstIterator</tt>s explicitly in your code. Here's a |
| 596 | small example that shows how to dump all instructions in a function to stderr |
| 597 | (<b>Note:</b> Dereferencing an <tt>InstIterator</tt> yields an |
| 598 | <tt>Instruction*</tt>, <i>not</i> an <tt>Instruction&</tt>!):</p> |
| 599 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 600 | <pre>#include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"<br>...<br>// Suppose F is a ptr to a function<br>for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)<br> cerr << **i << "\n";<br></pre> |
Joel Stanley | e7be650 | 2002-09-09 15:50:33 +0000 | [diff] [blame] | 601 | Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a |
| 602 | worklist with its initial contents. For example, if you wanted to |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 603 | initialize a worklist to contain all instructions in a <tt>Function</tt> |
| 604 | F, all you would need to do is something like: |
| 605 | <pre>std::set<Instruction*> worklist;<br>worklist.insert(inst_begin(F), inst_end(F));<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 606 | |
| 607 | <p>The STL set <tt>worklist</tt> would now contain all instructions in the |
| 608 | <tt>Function</tt> pointed to by F.</p> |
| 609 | |
| 610 | </div> |
| 611 | |
| 612 | <!-- _______________________________________________________________________ --> |
| 613 | <div class="doc_subsubsection"> |
| 614 | <a name="iterate_convert">Turning an iterator into a class pointer (and |
| 615 | vice-versa)</a> |
| 616 | </div> |
| 617 | |
| 618 | <div class="doc_text"> |
| 619 | |
| 620 | <p>Sometimes, it'll be useful to grab a reference (or pointer) to a class |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 621 | instance when all you've got at hand is an iterator. Well, extracting |
| 622 | a reference or a pointer from an iterator is very straightforward. |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 623 | Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and <tt>j</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 624 | is a <tt>BasicBlock::const_iterator</tt>:</p> |
| 625 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 626 | <pre> Instruction& inst = *i; // grab reference to instruction reference<br> Instruction* pinst = &*i; // grab pointer to instruction reference<br> const Instruction& inst = *j;<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 627 | |
| 628 | <p>However, the iterators you'll be working with in the LLVM framework are |
| 629 | special: they will automatically convert to a ptr-to-instance type whenever they |
| 630 | need to. Instead of dereferencing the iterator and then taking the address of |
| 631 | the result, you can simply assign the iterator to the proper pointer type and |
| 632 | you get the dereference and address-of operation as a result of the assignment |
| 633 | (behind the scenes, this is a result of overloading casting mechanisms). Thus |
| 634 | the last line of the last example,</p> |
| 635 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 636 | <pre>Instruction* pinst = &*i;</pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 637 | |
| 638 | <p>is semantically equivalent to</p> |
| 639 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 640 | <pre>Instruction* pinst = i;</pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 641 | |
| 642 | <p>It's also possible to turn a class pointer into the corresponding iterator. |
| 643 | Usually, this conversion is quite inexpensive. The following code snippet |
| 644 | illustrates use of the conversion constructors provided by LLVM iterators. By |
| 645 | using these, you can explicitly grab the iterator of something without actually |
| 646 | obtaining it via iteration over some structure:</p> |
| 647 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 648 | <pre>void printNextInstruction(Instruction* inst) {<br> BasicBlock::iterator it(inst);<br> ++it; // after this line, it refers to the instruction after *inst.<br> if (it != inst->getParent()->end()) cerr << *it << "\n";<br>}<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 649 | |
| 650 | <p>Of course, this example is strictly pedagogical, because it'd be much |
| 651 | better to explicitly grab the next instruction directly from inst.</p> |
| 652 | |
| 653 | </div> |
| 654 | |
| 655 | <!--_______________________________________________________________________--> |
| 656 | <div class="doc_subsubsection"> |
| 657 | <a name="iterate_complex">Finding call sites: a slightly more complex |
| 658 | example</a> |
| 659 | </div> |
| 660 | |
| 661 | <div class="doc_text"> |
| 662 | |
| 663 | <p>Say that you're writing a FunctionPass and would like to count all the |
| 664 | locations in the entire module (that is, across every <tt>Function</tt>) where a |
| 665 | certain function (i.e., some <tt>Function</tt>*) is already in scope. As you'll |
| 666 | learn later, you may want to use an <tt>InstVisitor</tt> to accomplish this in a |
| 667 | much more straightforward manner, but this example will allow us to explore how |
| 668 | you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this |
| 669 | is what we want to do:</p> |
| 670 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 671 | <pre>initialize callCounter to zero<br>for each Function f in the Module<br> for each BasicBlock b in f<br> for each Instruction i in b<br> if (i is a CallInst and calls the given function)<br> increment callCounter<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 672 | |
| 673 | <p>And the actual code is (remember, since we're writing a |
| 674 | <tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply has to |
| 675 | override the <tt>runOnFunction</tt> method...):</p> |
| 676 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 677 | <pre>Function* targetFunc = ...;<br><br>class OurFunctionPass : public FunctionPass {<br> public:<br> OurFunctionPass(): callCounter(0) { }<br><br> virtual runOnFunction(Function& F) {<br> for (Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {<br> for (BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {<br> if (<a |
| 678 | href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a |
| 679 | href="#CallInst">CallInst</a>>(&*i)) {<br> // we know we've encountered a call instruction, so we<br> // need to determine if it's a call to the<br> // function pointed to by m_func or not.<br> <br> if (callInst->getCalledFunction() == targetFunc)<br> ++callCounter;<br> }<br> }<br> }<br> <br> private:<br> unsigned callCounter;<br>};<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 680 | |
| 681 | </div> |
| 682 | |
Brian Gaeke | f1972c6 | 2003-11-07 19:25:45 +0000 | [diff] [blame] | 683 | <!--_______________________________________________________________________--> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 684 | <div class="doc_subsubsection"> |
| 685 | <a name="calls_and_invokes">Treating calls and invokes the same way</a> |
| 686 | </div> |
| 687 | |
| 688 | <div class="doc_text"> |
| 689 | |
| 690 | <p>You may have noticed that the previous example was a bit oversimplified in |
| 691 | that it did not deal with call sites generated by 'invoke' instructions. In |
| 692 | this, and in other situations, you may find that you want to treat |
| 693 | <tt>CallInst</tt>s and <tt>InvokeInst</tt>s the same way, even though their |
| 694 | most-specific common base class is <tt>Instruction</tt>, which includes lots of |
| 695 | less closely-related things. For these cases, LLVM provides a handy wrapper |
| 696 | class called <a |
| 697 | href="http://llvm.cs.uiuc.edu/doxygen/classCallSite.html"><tt>CallSite |
| 698 | </tt></a>. It is essentially a wrapper around an <tt>Instruction</tt> pointer, |
| 699 | with some methods that provide functionality common to <tt>CallInst</tt>s and |
| 700 | <tt>InvokeInst</tt>s.</p> |
| 701 | |
| 702 | <p>This class is supposed to have "value semantics". So it should be passed by |
| 703 | value, not by reference; it should not be dynamically allocated or deallocated |
| 704 | using <tt>operator new</tt> or <tt>operator delete</tt>. It is efficiently |
| 705 | copyable, assignable and constructable, with costs equivalents to that of a bare |
| 706 | pointer. (You will notice, if you look at its definition, that it has only a |
| 707 | single data member.)</p> |
| 708 | |
| 709 | </div> |
| 710 | |
Chris Lattner | 1a3105b | 2002-09-09 05:49:39 +0000 | [diff] [blame] | 711 | <!--_______________________________________________________________________--> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 712 | <div class="doc_subsubsection"> |
| 713 | <a name="iterate_chains">Iterating over def-use & use-def chains</a> |
| 714 | </div> |
| 715 | |
| 716 | <div class="doc_text"> |
| 717 | |
| 718 | <p>Frequently, we might have an instance of the <a |
| 719 | href="/doxygen/classValue.html">Value Class</a> and we want to determine which |
| 720 | <tt>User</tt>s use the <tt>Value</tt>. The list of all <tt>User</tt>s of a |
| 721 | particular <tt>Value</tt> is called a <i>def-use</i> chain. For example, let's |
| 722 | say we have a <tt>Function*</tt> named <tt>F</tt> to a particular function |
| 723 | <tt>foo</tt>. Finding all of the instructions that <i>use</i> <tt>foo</tt> is as |
| 724 | simple as iterating over the <i>def-use</i> chain of <tt>F</tt>:</p> |
| 725 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 726 | <pre>Function* F = ...;<br><br>for (Value::use_iterator i = F->use_begin(), e = F->use_end(); i != e; ++i) {<br> if (Instruction *Inst = dyn_cast<Instruction>(*i)) {<br> cerr << "F is used in instruction:\n";<br> cerr << *Inst << "\n";<br> }<br>}<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 727 | |
| 728 | <p>Alternately, it's common to have an instance of the <a |
| 729 | href="/doxygen/classUser.html">User Class</a> and need to know what |
| 730 | <tt>Value</tt>s are used by it. The list of all <tt>Value</tt>s used by a |
| 731 | <tt>User</tt> is known as a <i>use-def</i> chain. Instances of class |
| 732 | <tt>Instruction</tt> are common <tt>User</tt>s, so we might want to iterate over |
| 733 | all of the values that a particular instruction uses (that is, the operands of |
| 734 | the particular <tt>Instruction</tt>):</p> |
| 735 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 736 | <pre>Instruction* pi = ...;<br><br>for (User::op_iterator i = pi->op_begin(), e = pi->op_end(); i != e; ++i) {<br> Value* v = *i;<br> ...<br>}<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 737 | |
Chris Lattner | 1a3105b | 2002-09-09 05:49:39 +0000 | [diff] [blame] | 738 | <!-- |
| 739 | def-use chains ("finding all users of"): Value::use_begin/use_end |
| 740 | use-def chains ("finding all values used"): User::op_begin/op_end [op=operand] |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 741 | --> |
| 742 | |
| 743 | </div> |
| 744 | |
| 745 | <!-- ======================================================================= --> |
| 746 | <div class="doc_subsection"> |
| 747 | <a name="simplechanges">Making simple changes</a> |
| 748 | </div> |
| 749 | |
| 750 | <div class="doc_text"> |
| 751 | |
| 752 | <p>There are some primitive transformation operations present in the LLVM |
Joel Stanley | 753eb71 | 2002-09-11 22:32:24 +0000 | [diff] [blame] | 753 | infrastructure that are worth knowing about. When performing |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 754 | transformations, it's fairly common to manipulate the contents of basic |
| 755 | blocks. This section describes some of the common methods for doing so |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 756 | and gives example code.</p> |
| 757 | |
| 758 | </div> |
| 759 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 760 | <!--_______________________________________________________________________--> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 761 | <div class="doc_subsubsection"> |
| 762 | <a name="schanges_creating">Creating and inserting new |
| 763 | <tt>Instruction</tt>s</a> |
| 764 | </div> |
| 765 | |
| 766 | <div class="doc_text"> |
| 767 | |
| 768 | <p><i>Instantiating Instructions</i></p> |
| 769 | |
| 770 | <p>Creation of <tt>Instruction</tt>s is straightforward: simply call the |
| 771 | constructor for the kind of instruction to instantiate and provide the necessary |
| 772 | parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> a |
| 773 | (const-ptr-to) <tt>Type</tt>. Thus:</p> |
| 774 | |
| 775 | <pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre> |
| 776 | |
| 777 | <p>will create an <tt>AllocaInst</tt> instance that represents the allocation of |
| 778 | one integer in the current stack frame, at runtime. Each <tt>Instruction</tt> |
| 779 | subclass is likely to have varying default parameters which change the semantics |
| 780 | of the instruction, so refer to the <a |
| 781 | href="/doxygen/classInstruction.html">doxygen documentation for the subclass of |
| 782 | Instruction</a> that you're interested in instantiating.</p> |
| 783 | |
| 784 | <p><i>Naming values</i></p> |
| 785 | |
| 786 | <p>It is very useful to name the values of instructions when you're able to, as |
| 787 | this facilitates the debugging of your transformations. If you end up looking |
| 788 | at generated LLVM machine code, you definitely want to have logical names |
| 789 | associated with the results of instructions! By supplying a value for the |
| 790 | <tt>Name</tt> (default) parameter of the <tt>Instruction</tt> constructor, you |
| 791 | associate a logical name with the result of the instruction's execution at |
| 792 | runtime. For example, say that I'm writing a transformation that dynamically |
| 793 | allocates space for an integer on the stack, and that integer is going to be |
| 794 | used as some kind of index by some other code. To accomplish this, I place an |
| 795 | <tt>AllocaInst</tt> at the first point in the first <tt>BasicBlock</tt> of some |
| 796 | <tt>Function</tt>, and I'm intending to use it within the same |
| 797 | <tt>Function</tt>. I might do:</p> |
| 798 | |
| 799 | <pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre> |
| 800 | |
| 801 | <p>where <tt>indexLoc</tt> is now the logical name of the instruction's |
| 802 | execution value, which is a pointer to an integer on the runtime stack.</p> |
| 803 | |
| 804 | <p><i>Inserting instructions</i></p> |
| 805 | |
| 806 | <p>There are essentially two ways to insert an <tt>Instruction</tt> |
| 807 | into an existing sequence of instructions that form a <tt>BasicBlock</tt>:</p> |
| 808 | |
Joel Stanley | 9dd1ad6 | 2002-09-18 03:17:23 +0000 | [diff] [blame] | 809 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 810 | <li>Insertion into an explicit instruction list |
| 811 | |
| 812 | <p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> within that |
| 813 | <tt>BasicBlock</tt>, and a newly-created instruction we wish to insert |
| 814 | before <tt>*pi</tt>, we do the following: </p> |
| 815 | |
| 816 | <pre> BasicBlock *pb = ...;<br> Instruction *pi = ...;<br> Instruction *newInst = new Instruction(...);<br> pb->getInstList().insert(pi, newInst); // inserts newInst before pi in pb<br></pre></li> |
| 817 | |
| 818 | <li>Insertion into an implicit instruction list |
| 819 | |
| 820 | <p><tt>Instruction</tt> instances that are already in <tt>BasicBlock</tt>s |
| 821 | are implicitly associated with an existing instruction list: the instruction |
| 822 | list of the enclosing basic block. Thus, we could have accomplished the same |
| 823 | thing as the above code without being given a <tt>BasicBlock</tt> by doing: |
| 824 | </p> |
| 825 | |
| 826 | <pre> Instruction *pi = ...;<br> Instruction *newInst = new Instruction(...);<br> pi->getParent()->getInstList().insert(pi, newInst);<br></pre> |
| 827 | |
| 828 | <p>In fact, this sequence of steps occurs so frequently that the |
| 829 | <tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes provide |
| 830 | constructors which take (as a default parameter) a pointer to an |
| 831 | <tt>Instruction</tt> which the newly-created <tt>Instruction</tt> should |
| 832 | precede. That is, <tt>Instruction</tt> constructors are capable of |
| 833 | inserting the newly-created instance into the <tt>BasicBlock</tt> of a |
| 834 | provided instruction, immediately before that instruction. Using an |
| 835 | <tt>Instruction</tt> constructor with a <tt>insertBefore</tt> (default) |
| 836 | parameter, the above code becomes:</p> |
| 837 | |
| 838 | <pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre> |
| 839 | |
| 840 | <p>which is much cleaner, especially if you're creating a lot of |
| 841 | instructions and adding them to <tt>BasicBlock</tt>s.</p></li> |
| 842 | </ul> |
| 843 | |
| 844 | </div> |
| 845 | |
| 846 | <!--_______________________________________________________________________--> |
| 847 | <div class="doc_subsubsection"> |
| 848 | <a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a> |
| 849 | </div> |
| 850 | |
| 851 | <div class="doc_text"> |
| 852 | |
| 853 | <p>Deleting an instruction from an existing sequence of instructions that form a |
| 854 | <a href="#BasicBlock"><tt>BasicBlock</tt></a> is very straightforward. First, |
| 855 | you must have a pointer to the instruction that you wish to delete. Second, you |
| 856 | need to obtain the pointer to that instruction's basic block. You use the |
| 857 | pointer to the basic block to get its list of instructions and then use the |
| 858 | erase function to remove your instruction. For example:</p> |
| 859 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 860 | <pre> <a href="#Instruction">Instruction</a> *I = .. ;<br> <a |
| 861 | href="#BasicBlock">BasicBlock</a> *BB = I->getParent();<br> BB->getInstList().erase(I);<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 862 | |
| 863 | </div> |
| 864 | |
| 865 | <!--_______________________________________________________________________--> |
| 866 | <div class="doc_subsubsection"> |
| 867 | <a name="schanges_replacing">Replacing an <tt>Instruction</tt> with another |
| 868 | <tt>Value</tt></a> |
| 869 | </div> |
| 870 | |
| 871 | <div class="doc_text"> |
| 872 | |
| 873 | <p><i>Replacing individual instructions</i></p> |
| 874 | |
| 875 | <p>Including "<a href="/doxygen/BasicBlockUtils_8h-source.html">llvm/Transforms/Utils/BasicBlockUtils.h</a>" |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 876 | permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 877 | and <tt>ReplaceInstWithInst</tt>.</p> |
| 878 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 879 | <h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 880 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 881 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 882 | <li><tt>ReplaceInstWithValue</tt> |
| 883 | |
| 884 | <p>This function replaces all uses (within a basic block) of a given |
| 885 | instruction with a value, and then removes the original instruction. The |
| 886 | following example illustrates the replacement of the result of a particular |
| 887 | <tt>AllocaInst</tt> that allocates memory for a single integer with an null |
| 888 | pointer to an integer.</p> |
| 889 | |
| 890 | <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,<br> Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre></li> |
| 891 | |
| 892 | <li><tt>ReplaceInstWithInst</tt> |
| 893 | |
| 894 | <p>This function replaces a particular instruction with another |
| 895 | instruction. The following example illustrates the replacement of one |
| 896 | <tt>AllocaInst</tt> with another.</p> |
| 897 | |
| 898 | <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithInst(instToReplace->getParent()->getInstList(), ii,<br> new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt"));<br></pre></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 899 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 900 | |
| 901 | <p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p> |
| 902 | |
| 903 | <p>You can use <tt>Value::replaceAllUsesWith</tt> and |
| 904 | <tt>User::replaceUsesOfWith</tt> to change more than one use at a time. See the |
| 905 | doxygen documentation for the <a href="/doxygen/classValue.html">Value Class</a> |
| 906 | and <a href="/doxygen/classUser.html">User Class</a>, respectively, for more |
| 907 | information.</p> |
| 908 | |
| 909 | <!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out: |
| 910 | include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with: |
| 911 | ReplaceInstWithValue, ReplaceInstWithInst --> |
| 912 | |
| 913 | </div> |
| 914 | |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 915 | <!-- *********************************************************************** --> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 916 | <div class="doc_section"> |
| 917 | <a name="coreclasses">The Core LLVM Class Hierarchy Reference </a> |
| 918 | </div> |
| 919 | <!-- *********************************************************************** --> |
| 920 | |
| 921 | <div class="doc_text"> |
| 922 | |
| 923 | <p>The Core LLVM classes are the primary means of representing the program |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 924 | being inspected or transformed. The core LLVM classes are defined in |
| 925 | header files in the <tt>include/llvm/</tt> directory, and implemented in |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 926 | the <tt>lib/VMCore</tt> directory.</p> |
| 927 | |
| 928 | </div> |
| 929 | |
| 930 | <!-- ======================================================================= --> |
| 931 | <div class="doc_subsection"> |
| 932 | <a name="Value">The <tt>Value</tt> class</a> |
| 933 | </div> |
| 934 | |
| 935 | <div> |
| 936 | |
| 937 | <p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt> |
| 938 | <br> |
| 939 | doxygen info: <a href="/doxygen/classValue.html">Value Class</a></p> |
| 940 | |
| 941 | <p>The <tt>Value</tt> class is the most important class in the LLVM Source |
| 942 | base. It represents a typed value that may be used (among other things) as an |
| 943 | operand to an instruction. There are many different types of <tt>Value</tt>s, |
| 944 | such as <a href="#Constant"><tt>Constant</tt></a>s,<a |
| 945 | href="#Argument"><tt>Argument</tt></a>s. Even <a |
| 946 | href="#Instruction"><tt>Instruction</tt></a>s and <a |
| 947 | href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p> |
| 948 | |
| 949 | <p>A particular <tt>Value</tt> may be used many times in the LLVM representation |
| 950 | for a program. For example, an incoming argument to a function (represented |
| 951 | with an instance of the <a href="#Argument">Argument</a> class) is "used" by |
| 952 | every instruction in the function that references the argument. To keep track |
| 953 | of this relationship, the <tt>Value</tt> class keeps a list of all of the <a |
| 954 | href="#User"><tt>User</tt></a>s that is using it (the <a |
| 955 | href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM |
| 956 | graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents |
| 957 | def-use information in the program, and is accessible through the <tt>use_</tt>* |
| 958 | methods, shown below.</p> |
| 959 | |
| 960 | <p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, |
| 961 | and this <a href="#Type">Type</a> is available through the <tt>getType()</tt> |
| 962 | method. In addition, all LLVM values can be named. The "name" of the |
| 963 | <tt>Value</tt> is a symbolic string printed in the LLVM code:</p> |
| 964 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 965 | <pre> %<b>foo</b> = add int 1, 2<br></pre> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 966 | |
| 967 | <p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b> |
| 968 | that the name of any value may be missing (an empty string), so names should |
| 969 | <b>ONLY</b> be used for debugging (making the source code easier to read, |
| 970 | debugging printouts), they should not be used to keep track of values or map |
| 971 | between them. For this purpose, use a <tt>std::map</tt> of pointers to the |
| 972 | <tt>Value</tt> itself instead.</p> |
| 973 | |
| 974 | <p>One important aspect of LLVM is that there is no distinction between an SSA |
| 975 | variable and the operation that produces it. Because of this, any reference to |
| 976 | the value produced by an instruction (or the value available as an incoming |
| 977 | argument, for example) is represented as a direct pointer to the class that |
| 978 | represents this value. Although this may take some getting used to, it |
| 979 | simplifies the representation and makes it easier to manipulate.</p> |
| 980 | |
| 981 | </div> |
| 982 | |
| 983 | <!-- _______________________________________________________________________ --> |
| 984 | <div class="doc_subsubsection"> |
| 985 | <a name="m_Value">Important Public Members of the <tt>Value</tt> class</a> |
| 986 | </div> |
| 987 | |
| 988 | <div class="doc_text"> |
| 989 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 990 | <ul> |
| 991 | <li><tt>Value::use_iterator</tt> - Typedef for iterator over the |
| 992 | use-list<br> |
| 993 | <tt>Value::use_const_iterator</tt> - Typedef for const_iterator over |
| 994 | the use-list<br> |
| 995 | <tt>unsigned use_size()</tt> - Returns the number of users of the |
| 996 | value.<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 997 | <tt>bool use_empty()</tt> - Returns true if there are no users.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 998 | <tt>use_iterator use_begin()</tt> - Get an iterator to the start of |
| 999 | the use-list.<br> |
| 1000 | <tt>use_iterator use_end()</tt> - Get an iterator to the end of the |
| 1001 | use-list.<br> |
| 1002 | <tt><a href="#User">User</a> *use_back()</tt> - Returns the last |
| 1003 | element in the list. |
| 1004 | <p> These methods are the interface to access the def-use |
| 1005 | information in LLVM. As with all other iterators in LLVM, the naming |
| 1006 | conventions follow the conventions defined by the <a href="#stl">STL</a>.</p> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1007 | </li> |
| 1008 | <li><tt><a href="#Type">Type</a> *getType() const</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1009 | <p>This method returns the Type of the Value.</p> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1010 | </li> |
| 1011 | <li><tt>bool hasName() const</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1012 | <tt>std::string getName() const</tt><br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1013 | <tt>void setName(const std::string &Name)</tt> |
| 1014 | <p> This family of methods is used to access and assign a name to a <tt>Value</tt>, |
| 1015 | be aware of the <a href="#nameWarning">precaution above</a>.</p> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1016 | </li> |
| 1017 | <li><tt>void replaceAllUsesWith(Value *V)</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1018 | |
| 1019 | <p>This method traverses the use list of a <tt>Value</tt> changing all <a |
| 1020 | href="#User"><tt>User</tt>s</a> of the current value to refer to |
| 1021 | "<tt>V</tt>" instead. For example, if you detect that an instruction always |
| 1022 | produces a constant value (for example through constant folding), you can |
| 1023 | replace all uses of the instruction with the constant like this:</p> |
| 1024 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1025 | <pre> Inst->replaceAllUsesWith(ConstVal);<br></pre> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1026 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1027 | |
| 1028 | </div> |
| 1029 | |
| 1030 | <!-- ======================================================================= --> |
| 1031 | <div class="doc_subsection"> |
| 1032 | <a name="User">The <tt>User</tt> class</a> |
| 1033 | </div> |
| 1034 | |
| 1035 | <div class="doc_text"> |
| 1036 | |
| 1037 | <p> |
| 1038 | <tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1039 | doxygen info: <a href="/doxygen/classUser.html">User Class</a><br> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1040 | Superclass: <a href="#Value"><tt>Value</tt></a></p> |
| 1041 | |
| 1042 | <p>The <tt>User</tt> class is the common base class of all LLVM nodes that may |
| 1043 | refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands" |
| 1044 | that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is |
| 1045 | referring to. The <tt>User</tt> class itself is a subclass of |
| 1046 | <tt>Value</tt>.</p> |
| 1047 | |
| 1048 | <p>The operands of a <tt>User</tt> point directly to the LLVM <a |
| 1049 | href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static |
| 1050 | Single Assignment (SSA) form, there can only be one definition referred to, |
| 1051 | allowing this direct connection. This connection provides the use-def |
| 1052 | information in LLVM.</p> |
| 1053 | |
| 1054 | </div> |
| 1055 | |
| 1056 | <!-- _______________________________________________________________________ --> |
| 1057 | <div class="doc_subsubsection"> |
| 1058 | <a name="m_User">Important Public Members of the <tt>User</tt> class</a> |
| 1059 | </div> |
| 1060 | |
| 1061 | <div class="doc_text"> |
| 1062 | |
| 1063 | <p>The <tt>User</tt> class exposes the operand list in two ways: through |
| 1064 | an index access interface and through an iterator based interface.</p> |
| 1065 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1066 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1067 | <li><tt>Value *getOperand(unsigned i)</tt><br> |
| 1068 | <tt>unsigned getNumOperands()</tt> |
| 1069 | <p> These two methods expose the operands of the <tt>User</tt> in a |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1070 | convenient form for direct access.</p></li> |
| 1071 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1072 | <li><tt>User::op_iterator</tt> - Typedef for iterator over the operand |
| 1073 | list<br> |
| 1074 | <tt>User::op_const_iterator</tt> <tt>use_iterator op_begin()</tt> - |
| 1075 | Get an iterator to the start of the operand list.<br> |
| 1076 | <tt>use_iterator op_end()</tt> - Get an iterator to the end of the |
| 1077 | operand list. |
| 1078 | <p> Together, these methods make up the iterator based interface to |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1079 | the operands of a <tt>User</tt>.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1080 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1081 | |
| 1082 | </div> |
| 1083 | |
| 1084 | <!-- ======================================================================= --> |
| 1085 | <div class="doc_subsection"> |
| 1086 | <a name="Instruction">The <tt>Instruction</tt> class</a> |
| 1087 | </div> |
| 1088 | |
| 1089 | <div class="doc_text"> |
| 1090 | |
| 1091 | <p><tt>#include "</tt><tt><a |
| 1092 | href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt><br> |
| 1093 | doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br> |
| 1094 | Superclasses: <a href="#User"><tt>User</tt></a>, <a |
| 1095 | href="#Value"><tt>Value</tt></a></p> |
| 1096 | |
| 1097 | <p>The <tt>Instruction</tt> class is the common base class for all LLVM |
| 1098 | instructions. It provides only a few methods, but is a very commonly used |
| 1099 | class. The primary data tracked by the <tt>Instruction</tt> class itself is the |
| 1100 | opcode (instruction type) and the parent <a |
| 1101 | href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded |
| 1102 | into. To represent a specific type of instruction, one of many subclasses of |
| 1103 | <tt>Instruction</tt> are used.</p> |
| 1104 | |
| 1105 | <p> Because the <tt>Instruction</tt> class subclasses the <a |
| 1106 | href="#User"><tt>User</tt></a> class, its operands can be accessed in the same |
| 1107 | way as for other <a href="#User"><tt>User</tt></a>s (with the |
| 1108 | <tt>getOperand()</tt>/<tt>getNumOperands()</tt> and |
| 1109 | <tt>op_begin()</tt>/<tt>op_end()</tt> methods).</p> <p> An important file for |
| 1110 | the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> file. This |
| 1111 | file contains some meta-data about the various different types of instructions |
| 1112 | in LLVM. It describes the enum values that are used as opcodes (for example |
| 1113 | <tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), as well as the |
| 1114 | concrete sub-classes of <tt>Instruction</tt> that implement the instruction (for |
| 1115 | example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a |
| 1116 | href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, the use of macros in |
| 1117 | this file confuses doxygen, so these enum values don't show up correctly in the |
| 1118 | <a href="/doxygen/classInstruction.html">doxygen output</a>.</p> |
| 1119 | |
| 1120 | </div> |
| 1121 | |
| 1122 | <!-- _______________________________________________________________________ --> |
| 1123 | <div class="doc_subsubsection"> |
| 1124 | <a name="m_Instruction">Important Public Members of the <tt>Instruction</tt> |
| 1125 | class</a> |
| 1126 | </div> |
| 1127 | |
| 1128 | <div class="doc_text"> |
| 1129 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1130 | <ul> |
| 1131 | <li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1132 | <p>Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that |
| 1133 | this <tt>Instruction</tt> is embedded into.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1134 | <li><tt>bool mayWriteToMemory()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1135 | <p>Returns true if the instruction writes to memory, i.e. it is a |
| 1136 | <tt>call</tt>,<tt>free</tt>,<tt>invoke</tt>, or <tt>store</tt>.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1137 | <li><tt>unsigned getOpcode()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1138 | <p>Returns the opcode for the <tt>Instruction</tt>.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1139 | <li><tt><a href="#Instruction">Instruction</a> *clone() const</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1140 | <p>Returns another instance of the specified instruction, identical |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1141 | in all ways to the original except that the instruction has no parent |
| 1142 | (ie it's not embedded into a <a href="#BasicBlock"><tt>BasicBlock</tt></a>), |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1143 | and it has no name</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1144 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1145 | |
| 1146 | </div> |
| 1147 | |
| 1148 | <!-- ======================================================================= --> |
| 1149 | <div class="doc_subsection"> |
| 1150 | <a name="BasicBlock">The <tt>BasicBlock</tt> class</a> |
| 1151 | </div> |
| 1152 | |
| 1153 | <div class="doc_text"> |
| 1154 | |
| 1155 | <p><tt>#include "<a href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1156 | doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1157 | Superclass: <a href="#Value"><tt>Value</tt></a></p> |
| 1158 | |
| 1159 | <p>This class represents a single entry multiple exit section of the code, |
| 1160 | commonly known as a basic block by the compiler community. The |
| 1161 | <tt>BasicBlock</tt> class maintains a list of <a |
| 1162 | href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block. |
| 1163 | Matching the language definition, the last element of this list of instructions |
| 1164 | is always a terminator instruction (a subclass of the <a |
| 1165 | href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p> |
| 1166 | |
| 1167 | <p>In addition to tracking the list of instructions that make up the block, the |
| 1168 | <tt>BasicBlock</tt> class also keeps track of the <a |
| 1169 | href="#Function"><tt>Function</tt></a> that it is embedded into.</p> |
| 1170 | |
| 1171 | <p>Note that <tt>BasicBlock</tt>s themselves are <a |
| 1172 | href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions |
| 1173 | like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type |
| 1174 | <tt>label</tt>.</p> |
| 1175 | |
| 1176 | </div> |
| 1177 | |
| 1178 | <!-- _______________________________________________________________________ --> |
| 1179 | <div class="doc_subsubsection"> |
| 1180 | <a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt> |
| 1181 | class</a> |
| 1182 | </div> |
| 1183 | |
| 1184 | <div class="doc_text"> |
| 1185 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1186 | <ul> |
| 1187 | <li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a |
| 1188 | href="#Function">Function</a> *Parent = 0)</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1189 | <p>The <tt>BasicBlock</tt> constructor is used to create new basic |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1190 | blocks for insertion into a function. The constructor optionally takes |
| 1191 | a name for the new block, and a <a href="#Function"><tt>Function</tt></a> |
| 1192 | to insert it into. If the <tt>Parent</tt> parameter is specified, the |
| 1193 | new <tt>BasicBlock</tt> is automatically inserted at the end of the |
| 1194 | specified <a href="#Function"><tt>Function</tt></a>, if not specified, |
| 1195 | the BasicBlock must be manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1196 | </li> |
| 1197 | <li><tt>BasicBlock::iterator</tt> - Typedef for instruction list |
| 1198 | iterator<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1199 | <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1200 | <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,<tt>size()</tt>,<tt>empty()</tt>,<tt>rbegin()</tt>,<tt>rend() |
| 1201 | - </tt>STL style functions for accessing the instruction list. |
| 1202 | <p> These methods and typedefs are forwarding functions that have |
| 1203 | the same semantics as the standard library methods of the same names. |
| 1204 | These methods expose the underlying instruction list of a basic block in |
| 1205 | a way that is easy to manipulate. To get the full complement of |
| 1206 | container operations (including operations to update the list), you must |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1207 | use the <tt>getInstList()</tt> method.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1208 | <li><tt>BasicBlock::InstListType &getInstList()</tt> |
| 1209 | <p> This method is used to get access to the underlying container |
| 1210 | that actually holds the Instructions. This method must be used when |
| 1211 | there isn't a forwarding function in the <tt>BasicBlock</tt> class for |
| 1212 | the operation that you would like to perform. Because there are no |
| 1213 | forwarding functions for "updating" operations, you need to use this if |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1214 | you want to update the contents of a <tt>BasicBlock</tt>.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1215 | <li><tt><a href="#Function">Function</a> *getParent()</tt> |
| 1216 | <p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1217 | the block is embedded into, or a null pointer if it is homeless.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1218 | <li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt> |
| 1219 | <p> Returns a pointer to the terminator instruction that appears at |
| 1220 | the end of the <tt>BasicBlock</tt>. If there is no terminator |
| 1221 | instruction, or if the last instruction in the block is not a |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1222 | terminator, then a null pointer is returned.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1223 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1224 | |
| 1225 | </div> |
| 1226 | |
| 1227 | <!-- ======================================================================= --> |
| 1228 | <div class="doc_subsection"> |
| 1229 | <a name="GlobalValue">The <tt>GlobalValue</tt> class</a> |
| 1230 | </div> |
| 1231 | |
| 1232 | <div class="doc_text"> |
| 1233 | |
| 1234 | <p><tt>#include "<a |
| 1235 | href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br> |
| 1236 | doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br> |
| 1237 | Superclasses: <a href="#User"><tt>User</tt></a>, <a |
| 1238 | href="#Value"><tt>Value</tt></a></p> |
| 1239 | |
| 1240 | <p>Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a |
| 1241 | href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are |
| 1242 | visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s. |
| 1243 | Because they are visible at global scope, they are also subject to linking with |
| 1244 | other globals defined in different translation units. To control the linking |
| 1245 | process, <tt>GlobalValue</tt>s know their linkage rules. Specifically, |
| 1246 | <tt>GlobalValue</tt>s know whether they have internal or external linkage, as |
| 1247 | defined by the <tt>LinkageTypes</tt> enumerator.</p> |
| 1248 | |
| 1249 | <p>If a <tt>GlobalValue</tt> has internal linkage (equivalent to being |
| 1250 | <tt>static</tt> in C), it is not visible to code outside the current translation |
| 1251 | unit, and does not participate in linking. If it has external linkage, it is |
| 1252 | visible to external code, and does participate in linking. In addition to |
| 1253 | linkage information, <tt>GlobalValue</tt>s keep track of which <a |
| 1254 | href="#Module"><tt>Module</tt></a> they are currently part of.</p> |
| 1255 | |
| 1256 | <p>Because <tt>GlobalValue</tt>s are memory objects, they are always referred to |
| 1257 | by their <b>address</b>. As such, the <a href="#Type"><tt>Type</tt></a> of a |
| 1258 | global is always a pointer to its contents. It is important to remember this |
| 1259 | when using the <tt>GetElementPtrInst</tt> instruction because this pointer must |
| 1260 | be dereferenced first. For example, if you have a <tt>GlobalVariable</tt> (a |
| 1261 | subclass of <tt>GlobalValue)</tt> that is an array of 24 ints, type <tt>[24 x |
| 1262 | int]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although |
| 1263 | the address of the first element of this array and the value of the |
| 1264 | <tt>GlobalVariable</tt> are the same, they have different types. The |
| 1265 | <tt>GlobalVariable</tt>'s type is <tt>[24 x int]</tt>. The first element's type |
| 1266 | is <tt>int.</tt> Because of this, accessing a global value requires you to |
| 1267 | dereference the pointer with <tt>GetElementPtrInst</tt> first, then its elements |
| 1268 | can be accessed. This is explained in the <a href="LangRef.html#globalvars">LLVM |
| 1269 | Language Reference Manual</a>.</p> |
| 1270 | |
| 1271 | </div> |
| 1272 | |
| 1273 | <!-- _______________________________________________________________________ --> |
| 1274 | <div class="doc_subsubsection"> |
| 1275 | <a name="m_GlobalValue">Important Public Members of the <tt>GlobalValue</tt> |
| 1276 | class</a> |
| 1277 | </div> |
| 1278 | |
| 1279 | <div class="doc_text"> |
| 1280 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1281 | <ul> |
| 1282 | <li><tt>bool hasInternalLinkage() const</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1283 | <tt>bool hasExternalLinkage() const</tt><br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1284 | <tt>void setInternalLinkage(bool HasInternalLinkage)</tt> |
| 1285 | <p> These methods manipulate the linkage characteristics of the <tt>GlobalValue</tt>.</p> |
| 1286 | <p> </p> |
| 1287 | </li> |
| 1288 | <li><tt><a href="#Module">Module</a> *getParent()</tt> |
| 1289 | <p> This returns the <a href="#Module"><tt>Module</tt></a> that the |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1290 | GlobalValue is currently embedded into.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1291 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1292 | |
| 1293 | </div> |
| 1294 | |
| 1295 | <!-- ======================================================================= --> |
| 1296 | <div class="doc_subsection"> |
| 1297 | <a name="Function">The <tt>Function</tt> class</a> |
| 1298 | </div> |
| 1299 | |
| 1300 | <div class="doc_text"> |
| 1301 | |
| 1302 | <p><tt>#include "<a |
| 1303 | href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt><br> doxygen |
| 1304 | info: <a href="/doxygen/classFunction.html">Function Class</a><br> Superclasses: |
| 1305 | <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a |
| 1306 | href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p> |
| 1307 | |
| 1308 | <p>The <tt>Function</tt> class represents a single procedure in LLVM. It is |
| 1309 | actually one of the more complex classes in the LLVM heirarchy because it must |
| 1310 | keep track of a large amount of data. The <tt>Function</tt> class keeps track |
| 1311 | of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a |
| 1312 | href="#Argument"><tt>Argument</tt></a>s, and a <a |
| 1313 | href="#SymbolTable"><tt>SymbolTable</tt></a>.</p> |
| 1314 | |
| 1315 | <p>The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most |
| 1316 | commonly used part of <tt>Function</tt> objects. The list imposes an implicit |
| 1317 | ordering of the blocks in the function, which indicate how the code will be |
| 1318 | layed out by the backend. Additionally, the first <a |
| 1319 | href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the |
| 1320 | <tt>Function</tt>. It is not legal in LLVM to explicitly branch to this initial |
| 1321 | block. There are no implicit exit nodes, and in fact there may be multiple exit |
| 1322 | nodes from a single <tt>Function</tt>. If the <a |
| 1323 | href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that |
| 1324 | the <tt>Function</tt> is actually a function declaration: the actual body of the |
| 1325 | function hasn't been linked in yet.</p> |
| 1326 | |
| 1327 | <p>In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the |
| 1328 | <tt>Function</tt> class also keeps track of the list of formal <a |
| 1329 | href="#Argument"><tt>Argument</tt></a>s that the function receives. This |
| 1330 | container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a> |
| 1331 | nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for |
| 1332 | the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.</p> |
| 1333 | |
| 1334 | <p>The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used |
| 1335 | LLVM feature that is only used when you have to look up a value by name. Aside |
| 1336 | from that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used |
| 1337 | internally to make sure that there are not conflicts between the names of <a |
| 1338 | href="#Instruction"><tt>Instruction</tt></a>s, <a |
| 1339 | href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a |
| 1340 | href="#Argument"><tt>Argument</tt></a>s in the function body.</p> |
| 1341 | |
| 1342 | </div> |
| 1343 | |
| 1344 | <!-- _______________________________________________________________________ --> |
| 1345 | <div class="doc_subsubsection"> |
| 1346 | <a name="m_Function">Important Public Members of the <tt>Function</tt> |
| 1347 | class</a> |
| 1348 | </div> |
| 1349 | |
| 1350 | <div class="doc_text"> |
| 1351 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1352 | <ul> |
| 1353 | <li><tt>Function(const </tt><tt><a href="#FunctionType">FunctionType</a> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1354 | *Ty, bool isInternal, const std::string &N = "", Module* Parent = 0)</tt> |
| 1355 | |
| 1356 | <p>Constructor used when you need to create new <tt>Function</tt>s to add |
| 1357 | the the program. The constructor must specify the type of the function to |
| 1358 | create and whether or not it should start out with internal or external |
| 1359 | linkage. The <a href="#FunctionType"><tt>FunctionType</tt></a> argument |
| 1360 | specifies the formal arguments and return value for the function. The same |
| 1361 | <a href="#FunctionTypel"><tt>FunctionType</tt></a> value can be used to |
| 1362 | create multiple functions. The <tt>Parent</tt> argument specifies the Module |
| 1363 | in which the function is defined. If this argument is provided, the function |
| 1364 | will automatically be inserted into that module's list of |
| 1365 | functions.</p></li> |
| 1366 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1367 | <li><tt>bool isExternal()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1368 | |
| 1369 | <p>Return whether or not the <tt>Function</tt> has a body defined. If the |
| 1370 | function is "external", it does not have a body, and thus must be resolved |
| 1371 | by linking with a function defined in a different translation unit.</p></li> |
| 1372 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1373 | <li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1374 | <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1375 | |
| 1376 | <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>, |
| 1377 | <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt> |
| 1378 | |
| 1379 | <p>These are forwarding methods that make it easy to access the contents of |
| 1380 | a <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a> |
| 1381 | list.</p></li> |
| 1382 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1383 | <li><tt>Function::BasicBlockListType &getBasicBlockList()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1384 | |
| 1385 | <p>Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This |
| 1386 | is necessary to use when you need to update the list or perform a complex |
| 1387 | action that doesn't have a forwarding method.</p></li> |
| 1388 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1389 | <li><tt>Function::aiterator</tt> - Typedef for the argument list |
| 1390 | iterator<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1391 | <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1392 | |
| 1393 | <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>, |
| 1394 | <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt> |
| 1395 | |
| 1396 | <p>These are forwarding methods that make it easy to access the contents of |
| 1397 | a <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> |
| 1398 | list.</p></li> |
| 1399 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1400 | <li><tt>Function::ArgumentListType &getArgumentList()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1401 | |
| 1402 | <p>Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is |
| 1403 | necessary to use when you need to update the list or perform a complex |
| 1404 | action that doesn't have a forwarding method.</p></li> |
| 1405 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1406 | <li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryBlock()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1407 | |
| 1408 | <p>Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the |
| 1409 | function. Because the entry block for the function is always the first |
| 1410 | block, this returns the first block of the <tt>Function</tt>.</p></li> |
| 1411 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1412 | <li><tt><a href="#Type">Type</a> *getReturnType()</tt><br> |
| 1413 | <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1414 | |
| 1415 | <p>This traverses the <a href="#Type"><tt>Type</tt></a> of the |
| 1416 | <tt>Function</tt> and returns the return type of the function, or the <a |
| 1417 | href="#FunctionType"><tt>FunctionType</tt></a> of the actual |
| 1418 | function.</p></li> |
| 1419 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1420 | <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1421 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1422 | <p> Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1423 | for this <tt>Function</tt>.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1424 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1425 | |
| 1426 | </div> |
| 1427 | |
| 1428 | <!-- ======================================================================= --> |
| 1429 | <div class="doc_subsection"> |
| 1430 | <a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a> |
| 1431 | </div> |
| 1432 | |
| 1433 | <div class="doc_text"> |
| 1434 | |
| 1435 | <p><tt>#include "<a |
| 1436 | href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt> |
| 1437 | <br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1438 | doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1439 | Class</a><br> Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a |
| 1440 | href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p> |
| 1441 | |
| 1442 | <p>Global variables are represented with the (suprise suprise) |
| 1443 | <tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are also |
| 1444 | subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are |
| 1445 | always referenced by their address (global values must live in memory, so their |
| 1446 | "name" refers to their address). See <a |
| 1447 | href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global variables |
| 1448 | may have an initial value (which must be a <a |
| 1449 | href="#Constant"><tt>Constant</tt></a>), and if they have an initializer, they |
| 1450 | may be marked as "constant" themselves (indicating that their contents never |
| 1451 | change at runtime).</p> |
| 1452 | |
| 1453 | </div> |
| 1454 | |
| 1455 | <!-- _______________________________________________________________________ --> |
| 1456 | <div class="doc_subsubsection"> |
| 1457 | <a name="m_GlobalVariable">Important Public Members of the |
| 1458 | <tt>GlobalVariable</tt> class</a> |
| 1459 | </div> |
| 1460 | |
| 1461 | <div class="doc_text"> |
| 1462 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1463 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1464 | <li><tt>GlobalVariable(const </tt><tt><a href="#Type">Type</a> *Ty, bool |
| 1465 | isConstant, LinkageTypes& Linkage, <a href="#Constant">Constant</a> |
| 1466 | *Initializer = 0, const std::string &Name = "", Module* Parent = 0)</tt> |
| 1467 | |
| 1468 | <p>Create a new global variable of the specified type. If |
| 1469 | <tt>isConstant</tt> is true then the global variable will be marked as |
| 1470 | unchanging for the program. The Linkage parameter specifies the type of |
| 1471 | linkage (internal, external, weak, linkonce, appending) for the variable. If |
| 1472 | the linkage is InternalLinkage, WeakLinkage, or LinkOnceLinkage, then |
| 1473 | the resultant global variable will have internal linkage. AppendingLinkage |
| 1474 | concatenates together all instances (in different translation units) of the |
| 1475 | variable into a single variable but is only applicable to arrays. See |
| 1476 | the <a href="LangRef.html#modulestructure">LLVM Language Reference</a> for |
| 1477 | further details on linkage types. Optionally an initializer, a name, and the |
| 1478 | module to put the variable into may be specified for the global variable as |
| 1479 | well.</p></li> |
| 1480 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1481 | <li><tt>bool isConstant() const</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1482 | |
| 1483 | <p>Returns true if this is a global variable that is known not to |
| 1484 | be modified at runtime.</p></li> |
| 1485 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1486 | <li><tt>bool hasInitializer()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1487 | |
| 1488 | <p>Returns true if this <tt>GlobalVariable</tt> has an intializer.</p></li> |
| 1489 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1490 | <li><tt><a href="#Constant">Constant</a> *getInitializer()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1491 | |
| 1492 | <p>Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal |
| 1493 | to call this method if there is no initializer.</p></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1494 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1495 | |
| 1496 | </div> |
| 1497 | |
| 1498 | <!-- ======================================================================= --> |
| 1499 | <div class="doc_subsection"> |
| 1500 | <a name="Module">The <tt>Module</tt> class</a> |
| 1501 | </div> |
| 1502 | |
| 1503 | <div class="doc_text"> |
| 1504 | |
| 1505 | <p><tt>#include "<a |
| 1506 | href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt><br> doxygen info: |
| 1507 | <a href="/doxygen/classModule.html">Module Class</a></p> |
| 1508 | |
| 1509 | <p>The <tt>Module</tt> class represents the top level structure present in LLVM |
| 1510 | programs. An LLVM module is effectively either a translation unit of the |
| 1511 | original program or a combination of several translation units merged by the |
| 1512 | linker. The <tt>Module</tt> class keeps track of a list of <a |
| 1513 | href="#Function"><tt>Function</tt></a>s, a list of <a |
| 1514 | href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a |
| 1515 | href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few |
| 1516 | helpful member functions that try to make common operations easy.</p> |
| 1517 | |
| 1518 | </div> |
| 1519 | |
| 1520 | <!-- _______________________________________________________________________ --> |
| 1521 | <div class="doc_subsubsection"> |
| 1522 | <a name="m_Module">Important Public Members of the <tt>Module</tt> class</a> |
| 1523 | </div> |
| 1524 | |
| 1525 | <div class="doc_text"> |
| 1526 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1527 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1528 | <li><tt>Module::Module(std::string name = "")</tt></li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1529 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1530 | |
| 1531 | <p>Constructing a <a href="#Module">Module</a> is easy. You can optionally |
| 1532 | provide a name for it (probably based on the name of the translation unit).</p> |
| 1533 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1534 | <ul> |
| 1535 | <li><tt>Module::iterator</tt> - Typedef for function list iterator<br> |
Chris Lattner | 0377de4 | 2002-09-06 14:50:55 +0000 | [diff] [blame] | 1536 | <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1537 | |
| 1538 | <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>, |
| 1539 | <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt> |
| 1540 | |
| 1541 | <p>These are forwarding methods that make it easy to access the contents of |
| 1542 | a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a> |
| 1543 | list.</p></li> |
| 1544 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1545 | <li><tt>Module::FunctionListType &getFunctionList()</tt> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1546 | |
| 1547 | <p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is |
| 1548 | necessary to use when you need to update the list or perform a complex |
| 1549 | action that doesn't have a forwarding method.</p> |
| 1550 | |
| 1551 | <p><!-- Global Variable --></p></li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1552 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1553 | |
| 1554 | <hr> |
| 1555 | |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1556 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1557 | <li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br> |
| 1558 | |
| 1559 | <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br> |
| 1560 | |
| 1561 | <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>, |
| 1562 | <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt> |
| 1563 | |
| 1564 | <p> These are forwarding methods that make it easy to access the contents of |
| 1565 | a <tt>Module</tt> object's <a |
| 1566 | href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li> |
| 1567 | |
| 1568 | <li><tt>Module::GlobalListType &getGlobalList()</tt> |
| 1569 | |
| 1570 | <p>Returns the list of <a |
| 1571 | href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. This is necessary to |
| 1572 | use when you need to update the list or perform a complex action that |
| 1573 | doesn't have a forwarding method.</p> |
| 1574 | |
| 1575 | <p><!-- Symbol table stuff --> </p></li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1576 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1577 | |
| 1578 | <hr> |
| 1579 | |
| 1580 | <ul> |
| 1581 | <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt> |
| 1582 | |
| 1583 | <p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1584 | for this <tt>Module</tt>.</p> |
| 1585 | |
| 1586 | <p><!-- Convenience methods --></p></li> |
| 1587 | </ul> |
| 1588 | |
| 1589 | <hr> |
| 1590 | |
| 1591 | <ul> |
| 1592 | <li><tt><a href="#Function">Function</a> *getFunction(const std::string |
| 1593 | &Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt> |
| 1594 | |
| 1595 | <p>Look up the specified function in the <tt>Module</tt> <a |
| 1596 | href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return |
| 1597 | <tt>null</tt>.</p></li> |
| 1598 | |
| 1599 | <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const |
| 1600 | std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt> |
| 1601 | |
| 1602 | <p>Look up the specified function in the <tt>Module</tt> <a |
| 1603 | href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an |
| 1604 | external declaration for the function and return it.</p></li> |
| 1605 | |
| 1606 | <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt> |
| 1607 | |
| 1608 | <p>If there is at least one entry in the <a |
| 1609 | href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a |
| 1610 | href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty |
| 1611 | string.</p></li> |
| 1612 | |
| 1613 | <li><tt>bool addTypeName(const std::string &Name, const <a |
| 1614 | href="#Type">Type</a> *Ty)</tt> |
| 1615 | |
| 1616 | <p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1617 | mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this |
| 1618 | name, true is returned and the <a |
| 1619 | href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li> |
| 1620 | </ul> |
| 1621 | |
| 1622 | </div> |
| 1623 | |
| 1624 | <!-- ======================================================================= --> |
| 1625 | <div class="doc_subsection"> |
| 1626 | <a name="Constant">The <tt>Constant</tt> class and subclasses</a> |
| 1627 | </div> |
| 1628 | |
| 1629 | <div class="doc_text"> |
| 1630 | |
| 1631 | <p>Constant represents a base class for different types of constants. It |
| 1632 | is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt, |
| 1633 | ConstantArray etc for representing the various types of Constants.</p> |
| 1634 | |
| 1635 | </div> |
| 1636 | |
| 1637 | <!-- _______________________________________________________________________ --> |
| 1638 | <div class="doc_subsubsection"> |
| 1639 | <a name="m_Value">Important Public Methods</a> |
| 1640 | </div> |
| 1641 | |
| 1642 | <div class="doc_text"> |
| 1643 | |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1644 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1645 | <li><tt>bool isConstantExpr()</tt>: Returns true if it is a |
| 1646 | ConstantExpr |
| 1647 | <hr> Important Subclasses of Constant |
| 1648 | <p> </p> |
| 1649 | <ul> |
| 1650 | <li>ConstantSInt : This subclass of Constant represents a signed |
| 1651 | integer constant. |
| 1652 | <ul> |
| 1653 | <li><tt>int64_t getValue() const</tt>: Returns the underlying value of |
| 1654 | this constant. </li> |
| 1655 | </ul> |
| 1656 | </li> |
| 1657 | <li>ConstantUInt : This class represents an unsigned integer. |
| 1658 | <ul> |
| 1659 | <li><tt>uint64_t getValue() const</tt>: Returns the underlying value |
| 1660 | of this constant. </li> |
| 1661 | </ul> |
| 1662 | </li> |
| 1663 | <li>ConstantFP : This class represents a floating point constant. |
| 1664 | <ul> |
| 1665 | <li><tt>double getValue() const</tt>: Returns the underlying value of |
| 1666 | this constant. </li> |
| 1667 | </ul> |
| 1668 | </li> |
| 1669 | <li>ConstantBool : This represents a boolean constant. |
| 1670 | <ul> |
| 1671 | <li><tt>bool getValue() const</tt>: Returns the underlying value of |
| 1672 | this constant. </li> |
| 1673 | </ul> |
| 1674 | </li> |
| 1675 | <li>ConstantArray : This represents a constant array. |
| 1676 | <ul> |
| 1677 | <li><tt>const std::vector<Use> &getValues() const</tt>: |
| 1678 | Returns a Vecotr of component constants that makeup this array. </li> |
| 1679 | </ul> |
| 1680 | </li> |
| 1681 | <li>ConstantStruct : This represents a constant struct. |
| 1682 | <ul> |
| 1683 | <li><tt>const std::vector<Use> &getValues() const</tt>: |
| 1684 | Returns a Vecotr of component constants that makeup this array. </li> |
| 1685 | </ul> |
| 1686 | </li> |
| 1687 | <li>ConstantPointerRef : This represents a constant pointer value |
| 1688 | that is initialized to point to a global value, which lies at a |
| 1689 | constant fixed address. |
| 1690 | <ul> |
| 1691 | <li><tt>GlobalValue *getValue()</tt>: Returns the global |
| 1692 | value to which this pointer is pointing to. </li> |
| 1693 | </ul> |
| 1694 | </li> |
| 1695 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1696 | </li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1697 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1698 | |
| 1699 | </div> |
| 1700 | |
| 1701 | <!-- ======================================================================= --> |
| 1702 | <div class="doc_subsection"> |
| 1703 | <a name="Type">The <tt>Type</tt> class and Derived Types</a> |
| 1704 | </div> |
| 1705 | |
| 1706 | <div class="doc_text"> |
| 1707 | |
| 1708 | <p>Type as noted earlier is also a subclass of a Value class. Any primitive |
| 1709 | type (like int, short etc) in LLVM is an instance of Type Class. All other |
| 1710 | types are instances of subclasses of type like FunctionType, ArrayType |
| 1711 | etc. DerivedType is the interface for all such dervied types including |
| 1712 | FunctionType, ArrayType, PointerType, StructType. Types can have names. They can |
| 1713 | be recursive (StructType). There exists exactly one instance of any type |
| 1714 | structure at a time. This allows using pointer equality of Type *s for comparing |
| 1715 | types.</p> |
| 1716 | |
| 1717 | </div> |
| 1718 | |
| 1719 | <!-- _______________________________________________________________________ --> |
| 1720 | <div class="doc_subsubsection"> |
| 1721 | <a name="m_Value">Important Public Methods</a> |
| 1722 | </div> |
| 1723 | |
| 1724 | <div class="doc_text"> |
| 1725 | |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1726 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1727 | |
| 1728 | <li><tt>PrimitiveID getPrimitiveID() const</tt>: Returns the base type of the |
| 1729 | type.</li> |
| 1730 | |
| 1731 | <li><tt>bool isSigned() const</tt>: Returns whether an integral numeric type |
| 1732 | is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is |
| 1733 | not true for Float and Double. </li> |
| 1734 | |
| 1735 | <li><tt>bool isUnsigned() const</tt>: Returns whether a numeric type is |
| 1736 | unsigned. This is not quite the complement of isSigned... nonnumeric types |
| 1737 | return false as they do with isSigned. This returns true for UByteTy, |
| 1738 | UShortTy, UIntTy, and ULongTy. </li> |
| 1739 | |
| 1740 | <li><tt>bool isInteger() const</tt>: Equilivent to isSigned() || isUnsigned(), |
| 1741 | but with only a single virtual function invocation.</li> |
| 1742 | |
| 1743 | <li><tt>bool isIntegral() const</tt>: Returns true if this is an integral |
| 1744 | type, which is either Bool type or one of the Integer types.</li> |
| 1745 | |
| 1746 | <li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two |
| 1747 | floating point types.</li> |
| 1748 | |
| 1749 | <li><tt>bool isRecursive() const</tt>: Returns rue if the type graph contains |
| 1750 | a cycle.</li> |
| 1751 | |
| 1752 | <li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if |
| 1753 | this type can be converted to 'Ty' without any reinterpretation of bits. For |
| 1754 | example, uint to int.</li> |
| 1755 | |
| 1756 | <li><tt>bool isPrimitiveType() const</tt>: Returns true if it is a primitive |
| 1757 | type.</li> |
| 1758 | |
| 1759 | <li><tt>bool isDerivedType() const</tt>: Returns true if it is a derived |
| 1760 | type.</li> |
| 1761 | |
| 1762 | <li><tt>const Type * getContainedType (unsigned i) const</tt>: This method is |
| 1763 | used to implement the type iterator. For derived types, this returns the types |
| 1764 | 'contained' in the derived type, returning 0 when 'i' becomes invalid. This |
| 1765 | allows the user to iterate over the types in a struct, for example, really |
| 1766 | easily.</li> |
| 1767 | |
| 1768 | <li><tt>unsigned getNumContainedTypes() const</tt>: Return the number of types |
| 1769 | in the derived type. |
| 1770 | |
| 1771 | <hr> |
| 1772 | <p>Derived Types</p> |
| 1773 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1774 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1775 | <li>SequentialType : This is subclassed by ArrayType and PointerType |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1776 | <ul> |
| 1777 | <li><tt>const Type * getElementType() const</tt>: Returns the type of |
| 1778 | each of the elements in the sequential type. </li> |
| 1779 | </ul> |
| 1780 | </li> |
| 1781 | <li>ArrayType : This is a subclass of SequentialType and defines |
| 1782 | interface for array types. |
| 1783 | <ul> |
| 1784 | <li><tt>unsigned getNumElements() const</tt>: Returns the number of |
| 1785 | elements in the array. </li> |
| 1786 | </ul> |
| 1787 | </li> |
| 1788 | <li>PointerType : Subclass of SequentialType for pointer types. </li> |
| 1789 | <li>StructType : subclass of DerivedTypes for struct types </li> |
| 1790 | <li>FunctionType : subclass of DerivedTypes for function types. |
| 1791 | <ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1792 | <li><tt>bool isVarArg() const</tt>: Returns true if its a vararg |
| 1793 | function</li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1794 | <li><tt> const Type * getReturnType() const</tt>: Returns the |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1795 | return type of the function.</li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1796 | <li><tt> const ParamTypes &getParamTypes() const</tt>: |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1797 | Returns a vector of parameter types.</li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1798 | <li><tt>const Type * getParamType (unsigned i)</tt>: Returns |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1799 | the type of the ith parameter.</li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1800 | <li><tt> const unsigned getNumParams() const</tt>: Returns the |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1801 | number of formal parameters.</li> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1802 | </ul> |
| 1803 | </li> |
| 1804 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1805 | </li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1806 | </ul> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1807 | |
| 1808 | </div> |
| 1809 | |
| 1810 | <!-- ======================================================================= --> |
| 1811 | <div class="doc_subsection"> |
| 1812 | <a name="Argument">The <tt>Argument</tt> class</a> |
| 1813 | </div> |
| 1814 | |
| 1815 | <div class="doc_text"> |
| 1816 | |
| 1817 | <p>This subclass of Value defines the interface for incoming formal |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1818 | arguments to a function. A Function maitanis a list of its formal |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1819 | arguments. An argument has a pointer to the parent Function.</p> |
| 1820 | |
| 1821 | </div> |
| 1822 | |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1823 | <!-- *********************************************************************** --> |
Misha Brukman | 13fd15c | 2004-01-15 00:14:41 +0000 | [diff] [blame^] | 1824 | <hr> |
| 1825 | <address> |
| 1826 | <a href="http://jigsaw.w3.org/css-validator/check/referer"><img |
| 1827 | src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a> |
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| 1830 | |
| 1831 | <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and |
| 1832 | <a href="mailto:sabre@nondot.org">Chris Lattner</a><br> |
| 1833 | <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br> |
| 1834 | Last modified: $Date$ |
| 1835 | </address> |
| 1836 | |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1837 | </body> |
| 1838 | </html> |