Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 2 | <html> |
| 3 | <head> |
| 4 | <title>LLVM Programmer's Manual</title> |
| 5 | </head> |
| 6 | <body style="background-color: white;"> |
| 7 | <table width="100%" bgcolor="#330077" border="0" cellpadding="4" |
| 8 | cellspacing="0"> |
| 9 | <tbody> |
| 10 | <tr> |
| 11 | <td> <font size="+3" color="#eeeeff" |
| 12 | face="Georgia,Palatino,Times,Roman"><b>LLVM Programmer's Manual</b></font></td> |
| 13 | </tr> |
| 14 | </tbody> |
| 15 | </table> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 16 | <ol> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 17 | <li><a href="#introduction">Introduction</a> </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 18 | <li><a href="#general">General Information</a> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 19 | <ul> |
| 20 | <li><a href="#stl">The C++ Standard Template Library</a><!-- |
Chris Lattner | 986e0c9 | 2002-09-22 19:38:40 +0000 | [diff] [blame] | 21 | <li>The <tt>-time-passes</tt> option |
| 22 | <li>How to use the LLVM Makefile system |
| 23 | <li>How to write a regression test |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 24 | --> </li> |
Chris Lattner | 84b7f8d | 2003-08-01 22:20:59 +0000 | [diff] [blame] | 25 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 26 | </li> |
| 27 | <li><a href="#apis">Important and useful LLVM APIs</a> |
| 28 | <ul> |
| 29 | <li><a href="#isa">The <tt>isa<></tt>, <tt>cast<></tt> |
| 30 | and <tt>dyn_cast<></tt> templates</a> </li> |
| 31 | <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> |
| 32 | option</a> |
| 33 | <ul> |
| 34 | <li><a href="#DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt> |
| 35 | and the <tt>-debug-only</tt> option</a> </li> |
| 36 | </ul> |
| 37 | </li> |
| 38 | <li><a href="#Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt> |
| 39 | option</a><!-- |
Chris Lattner | 986e0c9 | 2002-09-22 19:38:40 +0000 | [diff] [blame] | 40 | <li>The <tt>InstVisitor</tt> template |
| 41 | <li>The general graph API |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 42 | --> </li> |
| 43 | </ul> |
| 44 | </li> |
Chris Lattner | ae7f759 | 2002-09-06 18:31:18 +0000 | [diff] [blame] | 45 | <li><a href="#common">Helpful Hints for Common Operations</a> |
Chris Lattner | ae7f759 | 2002-09-06 18:31:18 +0000 | [diff] [blame] | 46 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 47 | <li><a href="#inspection">Basic Inspection and Traversal Routines</a> |
| 48 | <ul> |
| 49 | <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s |
| 50 | in a <tt>Function</tt></a> </li> |
| 51 | <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s |
| 52 | in a <tt>BasicBlock</tt></a> </li> |
| 53 | <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s |
| 54 | in a <tt>Function</tt></a> </li> |
| 55 | <li><a href="#iterate_convert">Turning an iterator into a |
| 56 | class pointer</a> </li> |
| 57 | <li><a href="#iterate_complex">Finding call sites: a more |
| 58 | complex example</a> </li> |
| 59 | <li><a href="#calls_and_invokes">Treating calls and invokes |
| 60 | the same way</a> </li> |
| 61 | <li><a href="#iterate_chains">Iterating over def-use & |
| 62 | use-def chains</a> </li> |
| 63 | </ul> |
| 64 | </li> |
| 65 | <li><a href="#simplechanges">Making simple changes</a> |
| 66 | <ul> |
| 67 | <li><a href="#schanges_creating">Creating and inserting new |
| 68 | <tt>Instruction</tt>s</a> </li> |
| 69 | <li><a href="#schanges_deleting">Deleting <tt>Instruction</tt>s</a> </li> |
| 70 | <li><a href="#schanges_replacing">Replacing an <tt>Instruction</tt> |
| 71 | with another <tt>Value</tt></a> </li> |
| 72 | </ul> |
Chris Lattner | ae7f759 | 2002-09-06 18:31:18 +0000 | [diff] [blame] | 73 | <!-- |
| 74 | <li>Working with the Control Flow Graph |
| 75 | <ul> |
| 76 | <li>Accessing predecessors and successors of a <tt>BasicBlock</tt> |
| 77 | <li> |
| 78 | <li> |
| 79 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 80 | --> </li> |
| 81 | </ul> |
| 82 | </li> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 83 | <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 84 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 85 | <li><a href="#Value">The <tt>Value</tt> class</a> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 86 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 87 | <li><a href="#User">The <tt>User</tt> class</a> |
| 88 | <ul> |
| 89 | <li><a href="#Instruction">The <tt>Instruction</tt> class</a> |
| 90 | <ul> |
| 91 | <li> <a href="#GetElementPtrInst">The <span |
| 92 | style="font-family: monospace;">GetElementPtrInst</span> class</a><br> |
| 93 | </li> |
| 94 | </ul> |
| 95 | </li> |
| 96 | <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a> |
| 97 | <ul> |
| 98 | <li><a href="#BasicBlock">The <tt>BasicBlock</tt> |
| 99 | class</a> </li> |
| 100 | <li><a href="#Function">The <tt>Function</tt> class</a> </li> |
| 101 | <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> |
| 102 | class</a> </li> |
| 103 | </ul> |
| 104 | </li> |
| 105 | <li><a href="#Module">The <tt>Module</tt> class</a> </li> |
| 106 | <li><a href="#Constant">The <tt>Constant</tt> class</a> |
| 107 | <ul> |
| 108 | <li> <br> |
| 109 | </li> |
| 110 | <li> <br> |
| 111 | </li> |
| 112 | </ul> |
| 113 | </li> |
| 114 | </ul> |
| 115 | </li> |
| 116 | <li><a href="#Type">The <tt>Type</tt> class</a> </li> |
| 117 | <li><a href="#Argument">The <tt>Argument</tt> class</a> </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>The <tt>SymbolTable</tt> class </li> |
| 121 | <li>The <tt>ilist</tt> and <tt>iplist</tt> classes |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 122 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 123 | <li>Creating, inserting, moving and deleting from LLVM lists </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 124 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 125 | </li> |
| 126 | <li>Important iterator invalidation semantics to be aware of </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 127 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 128 | <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>,<a |
| 129 | href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>, and <a |
| 130 | href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b></p> |
| 131 | <p> </p> |
| 132 | </li> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 133 | </ol> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 134 | <!-- *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 135 | <table width="100%" bgcolor="#330077" border="0" cellpadding="4" |
| 136 | cellspacing="0"> |
| 137 | <tbody> |
| 138 | <tr> |
| 139 | <td align="center"><font color="#eeeeff" size="+2" |
| 140 | face="Georgia,Palatino"><b> <a name="introduction">Introduction </a></b></font></td> |
| 141 | </tr> |
| 142 | </tbody> |
| 143 | </table> |
| 144 | <ul> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 145 | <!-- *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 146 | This document is meant to highlight some of the important classes and |
| 147 | interfaces available in the LLVM source-base. This manual is not |
| 148 | intended to explain what LLVM is, how it works, and what LLVM code looks |
| 149 | like. It assumes that you know the basics of LLVM and are interested |
| 150 | in writing transformations or otherwise analyzing or manipulating the |
| 151 | code. |
| 152 | <p> This document should get you oriented so that you can find your |
| 153 | way in the continuously growing source code that makes up the LLVM |
| 154 | infrastructure. Note that this manual is not intended to serve as a |
| 155 | replacement for reading the source code, so if you think there should be |
| 156 | a method in one of these classes to do something, but it's not listed, |
| 157 | check the source. Links to the <a href="/doxygen/">doxygen</a> sources |
| 158 | are provided to make this as easy as possible.</p> |
| 159 | <p> The first section of this document describes general information |
| 160 | that is useful to know when working in the LLVM infrastructure, and the |
| 161 | second describes the Core LLVM classes. In the future this manual will |
| 162 | be extended with information describing how to use extension libraries, |
| 163 | such as dominator information, CFG traversal routines, and useful |
| 164 | utilities like the <tt><a href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> |
| 165 | template.</p> |
| 166 | <p><!-- *********************************************************************** --> </p> |
| 167 | </ul> |
| 168 | <table width="100%" bgcolor="#330077" border="0" cellpadding="4" |
| 169 | cellspacing="0"> |
| 170 | <tbody> |
| 171 | <tr> |
| 172 | <td align="center"><font color="#eeeeff" size="+2" |
| 173 | face="Georgia,Palatino"><b> <a name="general">General Information </a></b></font></td> |
| 174 | </tr> |
| 175 | </tbody> |
| 176 | </table> |
| 177 | <ul> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 178 | <!-- *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 179 | This section contains general information that is useful if you are |
| 180 | working in the LLVM source-base, but that isn't specific to any |
| 181 | particular API. |
| 182 | <p><!-- ======================================================================= --> </p> |
| 183 | </ul> |
| 184 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 185 | cellspacing="0"> |
| 186 | <tbody> |
| 187 | <tr> |
| 188 | <td> </td> |
| 189 | <td width="100%"> <font color="#eeeeff" |
| 190 | face="Georgia,Palatino"><b> <a name="stl">The C++ Standard Template |
| 191 | Library</a> </b></font></td> |
| 192 | </tr> |
| 193 | </tbody> |
| 194 | </table> |
| 195 | <ul> |
| 196 | LLVM makes heavy use of the C++ Standard Template Library (STL), |
| 197 | perhaps much more than you are used to, or have seen before. Because of |
| 198 | this, you might want to do a little background reading in the |
| 199 | techniques used and capabilities of the library. There are many good |
| 200 | pages that discuss the STL, and several books on the subject that you |
| 201 | can get, so it will not be discussed in this document. |
| 202 | <p> Here are some useful links:</p> |
| 203 | <p> </p> |
| 204 | <ol> |
| 205 | <li><a href="http://www.dinkumware.com/refxcpp.html">Dinkumware C++ |
| 206 | Library reference</a> - an excellent reference for the STL and other |
| 207 | parts of the standard C++ library. </li> |
| 208 | <li><a href="http://www.tempest-sw.com/cpp/">C++ In a Nutshell</a> - |
| 209 | This is an O'Reilly book in the making. It has a decent <a |
| 210 | href="http://www.tempest-sw.com/cpp/ch13-libref.html">Standard Library |
| 211 | Reference</a> that rivals Dinkumware's, and is actually free until the |
| 212 | book is published. </li> |
| 213 | <li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently |
| 214 | Asked Questions</a> </li> |
| 215 | <li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's |
| 216 | Guide</a> - Contains a useful <a |
| 217 | href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction |
| 218 | to the STL</a>. </li> |
| 219 | <li><a href="http://www.research.att.com/%7Ebs/C++.html">Bjarne |
| 220 | Stroustrup's C++ Page</a> </li> |
| 221 | </ol> |
| 222 | <p> You are also encouraged to take a look at the <a |
| 223 | href="CodingStandards.html">LLVM Coding Standards</a> guide which |
| 224 | focuses on how to write maintainable code more than where to put your |
| 225 | curly braces.</p> |
| 226 | <p><!-- ======================================================================= --> </p> |
| 227 | </ul> |
| 228 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 229 | cellspacing="0"> |
| 230 | <tbody> |
| 231 | <tr> |
| 232 | <td> </td> |
| 233 | <td width="100%"> <font color="#eeeeff" |
| 234 | face="Georgia,Palatino"><b> <a name="stl">Other useful references</a> </b></font></td> |
| 235 | </tr> |
| 236 | </tbody> |
| 237 | </table> |
| 238 | <ul> |
| 239 | LLVM is currently using CVS as its source versioning system. You may |
| 240 | find this reference handy: |
| 241 | <p> </p> |
| 242 | <ol> |
| 243 | <li><a href="http://www.psc.edu/%7Esemke/cvs_branches.html">CVS |
| 244 | Branch and Tag Primer</a></li> |
| 245 | </ol> |
| 246 | <p><!-- *********************************************************************** --> </p> |
| 247 | </ul> |
| 248 | <table width="100%" bgcolor="#330077" border="0" cellpadding="4" |
| 249 | cellspacing="0"> |
| 250 | <tbody> |
| 251 | <tr> |
| 252 | <td align="center"><font color="#eeeeff" size="+2" |
| 253 | face="Georgia,Palatino"><b> <a name="apis">Important and useful LLVM |
| 254 | APIs </a></b></font></td> |
| 255 | </tr> |
| 256 | </tbody> |
| 257 | </table> |
| 258 | <ul> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 259 | <!-- *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 260 | Here we highlight some LLVM APIs that are generally useful and good to |
| 261 | know about when writing transformations. |
| 262 | <p><!-- ======================================================================= --> </p> |
| 263 | </ul> |
| 264 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 265 | cellspacing="0"> |
| 266 | <tbody> |
| 267 | <tr> |
| 268 | <td> </td> |
| 269 | <td width="100%"> <font color="#eeeeff" |
| 270 | face="Georgia,Palatino"><b> <a name="isa">The isa<>, |
| 271 | cast<> and dyn_cast<> templates</a> </b></font></td> |
| 272 | </tr> |
| 273 | </tbody> |
| 274 | </table> |
| 275 | <ul> |
| 276 | The LLVM source-base makes extensive use of a custom form of RTTI. |
| 277 | These templates have many similarities to the C++ <tt>dynamic_cast<></tt> |
| 278 | operator, but they don't have some drawbacks (primarily stemming from |
| 279 | the fact that <tt>dynamic_cast<></tt> only works on classes that |
| 280 | have a v-table). Because they are used so often, you must know what they |
| 281 | do and how they work. All of these templates are defined in the <a |
| 282 | href="/doxygen/Casting_8h-source.html"><tt>Support/Casting.h</tt></a> |
| 283 | file (note that you very rarely have to include this file directly). |
| 284 | <p> </p> |
| 285 | <dl> |
| 286 | <dt><tt>isa<></tt>: </dt> |
| 287 | <dd>The <tt>isa<></tt> operator works exactly like the Java "<tt>instanceof</tt>" |
| 288 | operator. It returns true or false depending on whether a reference or |
| 289 | pointer points to an instance of the specified class. This can be very |
| 290 | useful for constraint checking of various sorts (example below). |
| 291 | <p> </p> |
| 292 | </dd> |
| 293 | <dt><tt>cast<></tt>: </dt> |
| 294 | <dd>The <tt>cast<></tt> operator is a "checked cast" |
| 295 | operation. It converts a pointer or reference from a base class to a |
| 296 | derived cast, causing an assertion failure if it is not really an |
| 297 | instance of the right type. This should be used in cases where you have |
| 298 | some information that makes you believe that something is of the right |
| 299 | type. An example of the <tt>isa<></tt> and <tt>cast<></tt> |
| 300 | template is: |
| 301 | <p> </p> |
| 302 | <pre>static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const Loop *L) {<br> if (isa<<a |
| 303 | href="#Constant">Constant</a>>(V) || isa<<a href="#Argument">Argument</a>>(V) || isa<<a |
| 304 | href="#GlobalValue">GlobalValue</a>>(V))<br> return true;<br><br> <i>// Otherwise, it must be an instruction...</i><br> return !L->contains(cast<<a |
| 305 | href="#Instruction">Instruction</a>>(V)->getParent());<br></pre> |
| 306 | <p> Note that you should <b>not</b> use an <tt>isa<></tt> |
| 307 | test followed by a <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt> |
| 308 | operator.</p> |
| 309 | <p> </p> |
| 310 | </dd> |
| 311 | <dt><tt>dyn_cast<></tt>: </dt> |
| 312 | <dd>The <tt>dyn_cast<></tt> operator is a "checking cast" |
| 313 | operation. It checks to see if the operand is of the specified type, and |
| 314 | if so, returns a pointer to it (this operator does not work with |
| 315 | references). If the operand is not of the correct type, a null pointer |
| 316 | is returned. Thus, this works very much like the <tt>dynamic_cast</tt> |
| 317 | operator in C++, and should be used in the same circumstances. |
| 318 | Typically, the <tt>dyn_cast<></tt> operator is used in an <tt>if</tt> |
| 319 | statement or some other flow control statement like this: |
| 320 | <p> </p> |
| 321 | <pre> if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a |
| 322 | href="#AllocationInst">AllocationInst</a>>(Val)) {<br> ...<br> }<br></pre> |
| 323 | <p> This form of the <tt>if</tt> statement effectively combines |
| 324 | together a call to <tt>isa<></tt> and a call to <tt>cast<></tt> |
| 325 | into one statement, which is very convenient.</p> |
| 326 | <p> Another common example is:</p> |
| 327 | <p> </p> |
| 328 | <pre> <i>// Loop over all of the phi nodes in a basic block</i><br> BasicBlock::iterator BBI = BB->begin();<br> for (; <a |
| 329 | href="#PhiNode">PHINode</a> *PN = dyn_cast<<a href="#PHINode">PHINode</a>>(BBI); ++BBI)<br> cerr << *PN;<br></pre> |
| 330 | <p> Note that the <tt>dyn_cast<></tt> operator, like C++'s <tt>dynamic_cast</tt> |
| 331 | or Java's <tt>instanceof</tt> operator, can be abused. In particular |
| 332 | you should not use big chained <tt>if/then/else</tt> blocks to check for |
| 333 | lots of different variants of classes. If you find yourself wanting to |
| 334 | do this, it is much cleaner and more efficient to use the InstVisitor |
| 335 | class to dispatch over the instruction type directly.</p> |
| 336 | <p> </p> |
| 337 | </dd> |
| 338 | <dt><tt>cast_or_null<></tt>: </dt> |
| 339 | <dd>The <tt>cast_or_null<></tt> operator works just like the <tt>cast<></tt> |
| 340 | operator, except that it allows for a null pointer as an argument (which |
| 341 | it then propagates). This can sometimes be useful, allowing you to |
| 342 | combine several null checks into one. |
| 343 | <p> </p> |
| 344 | </dd> |
| 345 | <dt><tt>dyn_cast_or_null<></tt>: </dt> |
| 346 | <dd>The <tt>dyn_cast_or_null<></tt> operator works just like |
| 347 | the <tt>dyn_cast<></tt> operator, except that it allows for a null |
| 348 | pointer as an argument (which it then propagates). This can sometimes |
| 349 | be useful, allowing you to combine several null checks into one. |
| 350 | <p> </p> |
| 351 | </dd> |
| 352 | </dl> |
| 353 | These five templates can be used with any classes, whether they have a |
| 354 | v-table or not. To add support for these templates, you simply need to |
| 355 | add <tt>classof</tt> static methods to the class you are interested |
| 356 | casting to. Describing this is currently outside the scope of this |
| 357 | document, but there are lots of examples in the LLVM source base. |
| 358 | <p><!-- ======================================================================= --> </p> |
| 359 | </ul> |
| 360 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 361 | cellspacing="0"> |
| 362 | <tbody> |
| 363 | <tr> |
| 364 | <td> </td> |
| 365 | <td width="100%"> <font color="#eeeeff" |
| 366 | face="Georgia,Palatino"><b> <a name="DEBUG">The <tt>DEBUG()</tt> macro |
| 367 | & <tt>-debug</tt> option</a> </b></font></td> |
| 368 | </tr> |
| 369 | </tbody> |
| 370 | </table> |
| 371 | <ul> |
| 372 | Often when working on your pass you will put a bunch of debugging |
| 373 | printouts and other code into your pass. After you get it working, you |
| 374 | want to remove it... but you may need it again in the future (to work |
| 375 | out new bugs that you run across). |
| 376 | <p> Naturally, because of this, you don't want to delete the debug |
| 377 | printouts, but you don't want them to always be noisy. A standard |
| 378 | compromise is to comment them out, allowing you to enable them if you |
| 379 | need them in the future.</p> |
| 380 | <p> The "<tt><a href="/doxygen/Debug_8h-source.html">Support/Debug.h</a></tt>" |
| 381 | file provides a macro named <tt>DEBUG()</tt> that is a much nicer |
| 382 | solution to this problem. Basically, you can put arbitrary code into |
| 383 | the argument of the <tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' |
| 384 | (or any other tool) is run with the '<tt>-debug</tt>' command line |
| 385 | argument: </p> |
| 386 | <pre> ... <br> DEBUG(std::cerr << "I am here!\n");<br> ...<br></pre> |
| 387 | <p> Then you can run your pass like this:</p> |
| 388 | <p> </p> |
| 389 | <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> |
| 390 | <p> Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution |
Chris Lattner | d8db4eb | 2003-11-27 21:17:48 +0000 | [diff] [blame] | 391 | allows you to not have to create "yet another" command line option for |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 392 | the debug output for your pass. Note that <tt>DEBUG()</tt> macros are |
| 393 | disabled for optimized builds, so they do not cause a performance impact |
| 394 | at all (for the same reason, they should also not contain |
| 395 | side-effects!).</p> |
| 396 | <p> One additional nice thing about the <tt>DEBUG()</tt> macro is that |
| 397 | you can enable or disable it directly in gdb. Just use "<tt>set |
| 398 | DebugFlag=0</tt>" or "<tt>set DebugFlag=1</tt>" from the gdb if the |
| 399 | program is running. If the program hasn't been started yet, you can |
| 400 | always just run it with <tt>-debug</tt>.</p> |
| 401 | <p><!-- _______________________________________________________________________ --> </p> |
| 402 | </ul> |
| 403 | <h4><a name="DEBUG_TYPE"> |
| 404 | <hr size="1">Fine grained debug info with <tt>DEBUG_TYPE()</tt> and the <tt>-debug-only</tt> |
| 405 | option</a> </h4> |
| 406 | <ul> |
Chris Lattner | 84b7f8d | 2003-08-01 22:20:59 +0000 | [diff] [blame] | 407 | Sometimes you may find yourself in a situation where enabling <tt>-debug</tt> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 408 | just turns on <b>too much</b> information (such as when working on the |
| 409 | code generator). If you want to enable debug information with more |
| 410 | fine-grained control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> |
| 411 | only option as follows: |
| 412 | <p> </p> |
| 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> |
| 414 | <p> Then you can run your pass like this:</p> |
| 415 | <p> </p> |
| 416 | <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> |
| 417 | <p> Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at |
| 418 | the top of a file, to specify the debug type for the entire module (if |
| 419 | you do this before you <tt>#include "Support/Debug.h"</tt>, you don't |
| 420 | have to insert the ugly <tt>#undef</tt>'s). Also, you should use names |
| 421 | more meaningful than "foo" and "bar", because there is no system in |
| 422 | place to ensure that names do not conflict. If two different modules |
| 423 | use the same string, they will all be turned on when the name is |
| 424 | specified. This allows, for example, all debug information for |
| 425 | instruction scheduling to be enabled with <tt>-debug-type=InstrSched</tt>, |
| 426 | even if the source lives in multiple files.</p> |
| 427 | <p><!-- ======================================================================= --> </p> |
| 428 | </ul> |
| 429 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 430 | cellspacing="0"> |
| 431 | <tbody> |
| 432 | <tr> |
| 433 | <td> </td> |
| 434 | <td width="100%"> <font color="#eeeeff" |
| 435 | face="Georgia,Palatino"><b> <a name="Statistic">The <tt>Statistic</tt> |
| 436 | template & <tt>-stats</tt> option</a> </b></font></td> |
| 437 | </tr> |
| 438 | </tbody> |
| 439 | </table> |
| 440 | <ul> |
| 441 | The "<tt><a href="/doxygen/Statistic_8h-source.html">Support/Statistic.h</a></tt>" |
| 442 | file provides a template named <tt>Statistic</tt> that is used as a |
| 443 | unified way to keep track of what the LLVM compiler is doing and how |
| 444 | effective various optimizations are. It is useful to see what |
| 445 | optimizations are contributing to making a particular program run |
| 446 | faster. |
| 447 | <p> Often you may run your pass on some big program, and you're |
| 448 | interested to see how many times it makes a certain transformation. |
| 449 | Although you can do this with hand inspection, or some ad-hoc method, |
| 450 | this is a real pain and not very useful for big programs. Using the <tt>Statistic</tt> |
| 451 | template makes it very easy to keep track of this information, and the |
| 452 | calculated information is presented in a uniform manner with the rest of |
| 453 | the passes being executed.</p> |
| 454 | <p> There are many examples of <tt>Statistic</tt> uses, but the basics |
| 455 | of using it are as follows:</p> |
| 456 | <p> </p> |
| 457 | <ol> |
| 458 | <li>Define your statistic like this: |
| 459 | <p> </p> |
| 460 | <pre>static Statistic<> NumXForms("mypassname", "The # of times I did stuff");<br></pre> |
| 461 | <p> The <tt>Statistic</tt> template can emulate just about any |
| 462 | data-type, but if you do not specify a template argument, it defaults to |
| 463 | acting like an unsigned int counter (this is usually what you want).</p> |
| 464 | <p> </p> |
| 465 | </li> |
| 466 | <li>Whenever you make a transformation, bump the counter: |
| 467 | <p> </p> |
| 468 | <pre> ++NumXForms; // I did stuff<br></pre> |
| 469 | <p> </p> |
| 470 | </li> |
| 471 | </ol> |
| 472 | <p> That's all you have to do. To get '<tt>opt</tt>' to print out the |
| 473 | statistics gathered, use the '<tt>-stats</tt>' option:</p> |
| 474 | <p> </p> |
| 475 | <pre> $ opt -stats -mypassname < program.bc > /dev/null<br> ... statistic output ...<br></pre> |
| 476 | <p> When running <tt>gccas</tt> on a C file from the SPEC benchmark |
| 477 | suite, it gives a report that looks like this:</p> |
| 478 | <p> </p> |
| 479 | <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> |
| 480 | <p> Obviously, with so many optimizations, having a unified framework |
| 481 | for this stuff is very nice. Making your pass fit well into the |
| 482 | framework makes it more maintainable and useful.</p> |
| 483 | <p><!-- *********************************************************************** --> </p> |
| 484 | </ul> |
| 485 | <table width="100%" bgcolor="#330077" border="0" cellpadding="4" |
| 486 | cellspacing="0"> |
| 487 | <tbody> |
| 488 | <tr> |
| 489 | <td align="center"><font color="#eeeeff" size="+2" |
| 490 | face="Georgia,Palatino"><b> <a name="common">Helpful Hints for Common |
| 491 | Operations </a></b></font></td> |
| 492 | </tr> |
| 493 | </tbody> |
| 494 | </table> |
| 495 | <ul> |
| 496 | <!-- |
Chris Lattner | 986e0c9 | 2002-09-22 19:38:40 +0000 | [diff] [blame] | 497 | *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 498 | This section describes how to perform some very simple transformations |
| 499 | of LLVM code. This is meant to give examples of common idioms used, |
| 500 | showing the practical side of LLVM transformations. |
| 501 | <p> Because this is a "how-to" section, you should also read about the |
| 502 | main classes that you will be working with. The <a href="#coreclasses">Core |
| 503 | LLVM Class Hierarchy Reference</a> contains details and descriptions of |
| 504 | the main classes that you should know about.</p> |
| 505 | <p><!-- NOTE: this section should be heavy on example code --><!-- ======================================================================= --> </p> |
| 506 | </ul> |
| 507 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 508 | cellspacing="0"> |
| 509 | <tbody> |
| 510 | <tr> |
| 511 | <td> </td> |
| 512 | <td width="100%"> <font color="#eeeeff" |
| 513 | face="Georgia,Palatino"><b> <a name="inspection">Basic Inspection and |
| 514 | Traversal Routines</a> </b></font></td> |
| 515 | </tr> |
| 516 | </tbody> |
| 517 | </table> |
| 518 | <ul> |
| 519 | The LLVM compiler infrastructure have many different data structures |
| 520 | that may be traversed. Following the example of the C++ standard |
| 521 | template library, the techniques used to traverse these various data |
| 522 | structures are all basically the same. For a enumerable sequence of |
| 523 | values, the <tt>XXXbegin()</tt> function (or method) returns an iterator |
| 524 | to the start of the sequence, the <tt>XXXend()</tt> function returns an |
| 525 | iterator pointing to one past the last valid element of the sequence, |
| 526 | and there is some <tt>XXXiterator</tt> data type that is common between |
| 527 | the two operations. |
| 528 | <p> Because the pattern for iteration is common across many different |
| 529 | aspects of the program representation, the standard template library |
| 530 | algorithms may be used on them, and it is easier to remember how to |
| 531 | iterate. First we show a few common examples of the data structures that |
| 532 | need to be traversed. Other data structures are traversed in very |
| 533 | similar ways.</p> |
| 534 | <p><!-- _______________________________________________________________________ --> </p> |
| 535 | </ul> |
| 536 | <h4> |
| 537 | <hr size="1"><a name="iterate_function">Iterating over the </a><a |
| 538 | href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a href="#Function"><tt>Function</tt></a> </h4> |
| 539 | <ul> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 540 | It's quite common to have a <tt>Function</tt> instance that you'd like |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 541 | to transform in some way; in particular, you'd like to manipulate its <tt>BasicBlock</tt>s. |
| 542 | To facilitate this, you'll need to iterate over all of the <tt>BasicBlock</tt>s |
| 543 | that constitute the <tt>Function</tt>. The following is an example |
| 544 | that prints the name of a <tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s |
| 545 | it contains: |
| 546 | <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> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 547 | Note that i can be used as if it were a pointer for the purposes of |
| 548 | invoking member functions of the <tt>Instruction</tt> class. This is |
| 549 | because the indirection operator is overloaded for the iterator |
Chris Lattner | 7496ec5 | 2003-08-05 22:54:23 +0000 | [diff] [blame] | 550 | classes. In the above code, the expression <tt>i->size()</tt> is |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 551 | exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.<!-- _______________________________________________________________________ --> |
| 552 | </ul> |
| 553 | <h4> |
| 554 | <hr size="1"><a name="iterate_basicblock">Iterating over the </a><a |
| 555 | href="#Instruction"><tt>Instruction</tt></a>s in a <a |
| 556 | href="#BasicBlock"><tt>BasicBlock</tt></a> </h4> |
| 557 | <ul> |
| 558 | Just like when dealing with <tt>BasicBlock</tt>s in <tt>Function</tt>s, |
| 559 | it's easy to iterate over the individual instructions that make up <tt>BasicBlock</tt>s. |
| 560 | Here's a code snippet that prints out each instruction in a <tt>BasicBlock</tt>: |
| 561 | <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> |
| 562 | However, this isn't really the best way to print out the contents of a <tt>BasicBlock</tt>! |
| 563 | Since the ostream operators are overloaded for virtually anything |
| 564 | you'll care about, you could have just invoked the print routine on the |
| 565 | basic block itself: <tt>cerr << *blk << "\n";</tt>. |
| 566 | <p> Note that currently operator<< is implemented for <tt>Value*</tt>, |
| 567 | so it will print out the contents of the pointer, instead of the |
| 568 | pointer value you might expect. This is a deprecated interface that |
| 569 | will be removed in the future, so it's best not to depend on it. To |
| 570 | print out the pointer value for now, you must cast to <tt>void*</tt>.</p> |
| 571 | <p><!-- _______________________________________________________________________ --> </p> |
| 572 | </ul> |
| 573 | <h4> |
| 574 | <hr size="1"><a name="iterate_institer">Iterating over the </a><a |
| 575 | href="#Instruction"><tt>Instruction</tt></a>s in a <a href="#Function"><tt>Function</tt></a></h4> |
| 576 | <ul> |
| 577 | If you're finding that you commonly iterate over a <tt>Function</tt>'s <tt>BasicBlock</tt>s |
| 578 | and then that <tt>BasicBlock</tt>'s <tt>Instruction</tt>s, <tt>InstIterator</tt> |
| 579 | should be used instead. You'll need to include <a |
| 580 | href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>, |
| 581 | and then instantiate <tt>InstIterator</tt>s explicitly in your code. |
| 582 | Here's a small example that shows how to dump all instructions in a |
| 583 | function to stderr (<b>Note:</b> Dereferencing an <tt>InstIterator</tt> |
| 584 | yields an <tt>Instruction*</tt>, <i>not</i> an <tt>Instruction&</tt>!): |
| 585 | <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] | 586 | Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a |
| 587 | worklist with its initial contents. For example, if you wanted to |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 588 | initialize a worklist to contain all instructions in a <tt>Function</tt> |
| 589 | F, all you would need to do is something like: |
| 590 | <pre>std::set<Instruction*> worklist;<br>worklist.insert(inst_begin(F), inst_end(F));<br></pre> |
| 591 | The STL set <tt>worklist</tt> would now contain all instructions in the <tt>Function</tt> |
| 592 | pointed to by F.<!-- _______________________________________________________________________ --> |
| 593 | </ul> |
| 594 | <h4> |
| 595 | <hr size="1"><a name="iterate_convert">Turning an iterator into a class |
| 596 | pointer (and vice-versa) </a></h4> |
| 597 | <ul> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 598 | Sometimes, it'll be useful to grab a reference (or pointer) to a class |
| 599 | instance when all you've got at hand is an iterator. Well, extracting |
| 600 | a reference or a pointer from an iterator is very straightforward. |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 601 | Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and <tt>j</tt> |
| 602 | is a <tt>BasicBlock::const_iterator</tt>: |
| 603 | <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> |
| 604 | However, the iterators you'll be working with in the LLVM framework are |
| 605 | special: they will automatically convert to a ptr-to-instance type |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 606 | whenever they need to. Instead of dereferencing the iterator and then |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 607 | taking the address of the result, you can simply assign the iterator to |
| 608 | the proper pointer type and you get the dereference and address-of |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 609 | operation as a result of the assignment (behind the scenes, this is a |
| 610 | result of overloading casting mechanisms). Thus the last line of the |
| 611 | last example, |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 612 | <pre>Instruction* pinst = &*i;</pre> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 613 | is semantically equivalent to |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 614 | <pre>Instruction* pinst = i;</pre> |
Joel Stanley | e7be650 | 2002-09-09 15:50:33 +0000 | [diff] [blame] | 615 | It's also possible to turn a class pointer into the corresponding |
| 616 | iterator. Usually, this conversion is quite inexpensive. The |
| 617 | following code snippet illustrates use of the conversion constructors |
| 618 | provided by LLVM iterators. By using these, you can explicitly grab |
| 619 | the iterator of something without actually obtaining it via iteration |
| 620 | over some structure: |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 621 | <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> |
Joel Stanley | aaeb1c1 | 2002-09-06 23:42:40 +0000 | [diff] [blame] | 622 | Of course, this example is strictly pedagogical, because it'd be much |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 623 | better to explicitly grab the next instruction directly from inst.<!--_______________________________________________________________________--> |
| 624 | </ul> |
| 625 | <h4> |
| 626 | <hr size="1"><a name="iterate_complex">Finding call sites: a slightly |
| 627 | more complex example </a></h4> |
| 628 | <ul> |
Joel Stanley | 9b96c44 | 2002-09-06 21:55:13 +0000 | [diff] [blame] | 629 | Say that you're writing a FunctionPass and would like to count all the |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 630 | locations in the entire module (that is, across every <tt>Function</tt>) |
| 631 | where a certain function (i.e., some <tt>Function</tt>*) is already in |
| 632 | scope. As you'll learn later, you may want to use an <tt>InstVisitor</tt> |
| 633 | to accomplish this in a much more straightforward manner, but this |
| 634 | example will allow us to explore how you'd do it if you didn't have <tt>InstVisitor</tt> |
| 635 | around. In pseudocode, this is what we want to do: |
| 636 | <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> |
| 637 | And the actual code is (remember, since we're writing a <tt>FunctionPass</tt>, |
| 638 | our <tt>FunctionPass</tt>-derived class simply has to override the <tt>runOnFunction</tt> |
| 639 | method...): |
| 640 | <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 |
| 641 | href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a |
| 642 | 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> |
Brian Gaeke | f1972c6 | 2003-11-07 19:25:45 +0000 | [diff] [blame] | 643 | <!--_______________________________________________________________________--> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 644 | </ul> |
| 645 | <h4> |
| 646 | <hr size="1"><a name="calls_and_invokes">Treating calls and invokes the |
| 647 | same way</a></h4> |
| 648 | <ul> |
| 649 | <p>You may have noticed that the previous example was a bit |
Brian Gaeke | f1972c6 | 2003-11-07 19:25:45 +0000 | [diff] [blame] | 650 | oversimplified in that it did not deal with call sites generated by |
| 651 | 'invoke' instructions. In this, and in other situations, you may find |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 652 | that you want to treat <tt>CallInst</tt>s and <tt>InvokeInst</tt>s |
| 653 | the same way, even though their most-specific common base class is <tt>Instruction</tt>, |
| 654 | which includes lots of less closely-related things. For these cases, |
| 655 | LLVM provides a handy wrapper class called <a |
| 656 | href="http://llvm.cs.uiuc.edu/doxygen/classCallSite.html"><tt>CallSite </tt></a>. |
| 657 | It is essentially a wrapper around an <tt>Instruction</tt> pointer, |
| 658 | with some methods that provide functionality common to <tt>CallInst</tt>s |
| 659 | and <tt>InvokeInst</tt>s.</p> |
| 660 | <p>This class is supposed to have "value semantics". So it should be |
Brian Gaeke | f1972c6 | 2003-11-07 19:25:45 +0000 | [diff] [blame] | 661 | passed by value, not by reference; it should not be dynamically |
| 662 | allocated or deallocated using <tt>operator new</tt> or <tt>operator |
| 663 | delete</tt>. It is efficiently copyable, assignable and constructable, |
| 664 | with costs equivalents to that of a bare pointer. (You will notice, if |
| 665 | you look at its definition, that it has only a single data member.)</p> |
Chris Lattner | 1a3105b | 2002-09-09 05:49:39 +0000 | [diff] [blame] | 666 | <!--_______________________________________________________________________--> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 667 | </ul> |
| 668 | <h4> |
| 669 | <hr size="1"><a name="iterate_chains">Iterating over def-use & |
| 670 | use-def chains</a></h4> |
| 671 | <ul> |
Joel Stanley | 01040b2 | 2002-09-11 20:50:04 +0000 | [diff] [blame] | 672 | Frequently, we might have an instance of the <a |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 673 | href="/doxygen/classValue.html">Value Class</a> and we want to |
Joel Stanley | 01040b2 | 2002-09-11 20:50:04 +0000 | [diff] [blame] | 674 | determine which <tt>User</tt>s use the <tt>Value</tt>. The list of |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 675 | all <tt>User</tt>s of a particular <tt>Value</tt> is called a <i>def-use</i> |
| 676 | chain. For example, let's say we have a <tt>Function*</tt> named <tt>F</tt> |
| 677 | to a particular function <tt>foo</tt>. Finding all of the instructions |
| 678 | that <i>use</i> <tt>foo</tt> is as simple as iterating over the <i>def-use</i> |
| 679 | chain of <tt>F</tt>: |
| 680 | <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> |
Joel Stanley | 01040b2 | 2002-09-11 20:50:04 +0000 | [diff] [blame] | 681 | Alternately, it's common to have an instance of the <a |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 682 | href="/doxygen/classUser.html">User Class</a> and need to know what <tt>Value</tt>s |
| 683 | are used by it. The list of all <tt>Value</tt>s used by a <tt>User</tt> |
| 684 | is known as a <i>use-def</i> chain. Instances of class <tt>Instruction</tt> |
| 685 | are common <tt>User</tt>s, so we might want to iterate over all of the |
| 686 | values that a particular instruction uses (that is, the operands of the |
| 687 | particular <tt>Instruction</tt>): |
| 688 | <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> |
Chris Lattner | 1a3105b | 2002-09-09 05:49:39 +0000 | [diff] [blame] | 689 | <!-- |
| 690 | def-use chains ("finding all users of"): Value::use_begin/use_end |
| 691 | use-def chains ("finding all values used"): User::op_begin/op_end [op=operand] |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 692 | --><!-- ======================================================================= --> |
| 693 | </ul> |
| 694 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 695 | cellspacing="0"> |
| 696 | <tbody> |
| 697 | <tr> |
| 698 | <td> </td> |
| 699 | <td width="100%"> <font color="#eeeeff" |
| 700 | face="Georgia,Palatino"><b> <a name="simplechanges">Making simple |
| 701 | changes</a> </b></font></td> |
| 702 | </tr> |
| 703 | </tbody> |
| 704 | </table> |
| 705 | <ul> |
Joel Stanley | 753eb71 | 2002-09-11 22:32:24 +0000 | [diff] [blame] | 706 | There are some primitive transformation operations present in the LLVM |
| 707 | infrastructure that are worth knowing about. When performing |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 708 | transformations, it's fairly common to manipulate the contents of basic |
| 709 | blocks. This section describes some of the common methods for doing so |
| 710 | and gives example code.<!--_______________________________________________________________________--> |
| 711 | </ul> |
| 712 | <h4> |
| 713 | <hr size="1"><a name="schanges_creating">Creating and inserting new <tt>Instruction</tt>s</a></h4> |
| 714 | <ul> |
| 715 | <i>Instantiating Instructions</i> |
| 716 | <p>Creation of <tt>Instruction</tt>s is straightforward: simply call |
| 717 | the constructor for the kind of instruction to instantiate and provide |
| 718 | the necessary parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> |
| 719 | a (const-ptr-to) <tt>Type</tt>. Thus: </p> |
| 720 | <pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre> |
Joel Stanley | 753eb71 | 2002-09-11 22:32:24 +0000 | [diff] [blame] | 721 | will create an <tt>AllocaInst</tt> instance that represents the |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 722 | allocation of one integer in the current stack frame, at runtime. Each <tt>Instruction</tt> |
| 723 | subclass is likely to have varying default parameters which change the |
| 724 | semantics of the instruction, so refer to the <a |
| 725 | href="/doxygen/classInstruction.html">doxygen documentation for the |
| 726 | subclass of Instruction</a> that you're interested in instantiating. |
| 727 | <p><i>Naming values</i></p> |
| 728 | <p> It is very useful to name the values of instructions when you're |
| 729 | able to, as this facilitates the debugging of your transformations. If |
| 730 | you end up looking at generated LLVM machine code, you definitely want |
| 731 | to have logical names associated with the results of instructions! By |
| 732 | supplying a value for the <tt>Name</tt> (default) parameter of the <tt>Instruction</tt> |
| 733 | constructor, you associate a logical name with the result of the |
| 734 | instruction's execution at runtime. For example, say that I'm writing a |
| 735 | transformation that dynamically allocates space for an integer on the |
| 736 | stack, and that integer is going to be used as some kind of index by |
| 737 | some other code. To accomplish this, I place an <tt>AllocaInst</tt> at |
| 738 | the first point in the first <tt>BasicBlock</tt> of some <tt>Function</tt>, |
| 739 | and I'm intending to use it within the same <tt>Function</tt>. I |
| 740 | might do: </p> |
| 741 | <pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre> |
Joel Stanley | 753eb71 | 2002-09-11 22:32:24 +0000 | [diff] [blame] | 742 | where <tt>indexLoc</tt> is now the logical name of the instruction's |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 743 | execution value, which is a pointer to an integer on the runtime stack. |
| 744 | <p><i>Inserting instructions</i></p> |
| 745 | <p> There are essentially two ways to insert an <tt>Instruction</tt> |
| 746 | into an existing sequence of instructions that form a <tt>BasicBlock</tt>:</p> |
| 747 | <ul> |
| 748 | <li>Insertion into an explicit instruction list |
| 749 | <p>Given a <tt>BasicBlock* pb</tt>, an <tt>Instruction* pi</tt> |
| 750 | within that <tt>BasicBlock</tt>, and a newly-created instruction we |
| 751 | wish to insert before <tt>*pi</tt>, we do the following: </p> |
| 752 | <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> |
| 753 | </li> |
| 754 | <li>Insertion into an implicit instruction list |
| 755 | <p><tt>Instruction</tt> instances that are already in <tt>BasicBlock</tt>s |
| 756 | are implicitly associated with an existing instruction list: the |
| 757 | instruction list of the enclosing basic block. Thus, we could have |
| 758 | accomplished the same thing as the above code without being given a <tt>BasicBlock</tt> |
| 759 | by doing: </p> |
| 760 | <pre> Instruction *pi = ...;<br> Instruction *newInst = new Instruction(...);<br> pi->getParent()->getInstList().insert(pi, newInst);<br></pre> |
| 761 | In fact, this sequence of steps occurs so frequently that the <tt>Instruction</tt> |
| 762 | class and <tt>Instruction</tt>-derived classes provide constructors |
| 763 | which take (as a default parameter) a pointer to an <tt>Instruction</tt> |
| 764 | which the newly-created <tt>Instruction</tt> should precede. That is, <tt>Instruction</tt> |
| 765 | constructors are capable of inserting the newly-created instance into |
| 766 | the <tt>BasicBlock</tt> of a provided instruction, immediately before |
| 767 | that instruction. Using an <tt>Instruction</tt> constructor with a <tt>insertBefore</tt> |
| 768 | (default) parameter, the above code becomes: |
| 769 | <pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre> |
Joel Stanley | 753eb71 | 2002-09-11 22:32:24 +0000 | [diff] [blame] | 770 | which is much cleaner, especially if you're creating a lot of |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 771 | instructions and adding them to <tt>BasicBlock</tt>s. </li> |
| 772 | </ul> |
| 773 | <!--_______________________________________________________________________--> |
Chris Lattner | 9ebf516 | 2002-09-12 19:08:16 +0000 | [diff] [blame] | 774 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 775 | <h4> |
| 776 | <hr size="1"><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4> |
Joel Stanley | 9dd1ad6 | 2002-09-18 03:17:23 +0000 | [diff] [blame] | 777 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 778 | Deleting an instruction from an existing sequence of instructions that |
| 779 | form a <a href="#BasicBlock"><tt>BasicBlock</tt></a> is very |
| 780 | straightforward. First, you must have a pointer to the instruction that |
| 781 | you wish to delete. Second, you need to obtain the pointer to that |
| 782 | instruction's basic block. You use the pointer to the basic block to |
| 783 | get its list of instructions and then use the erase function to remove |
| 784 | your instruction. |
| 785 | <p> For example:</p> |
| 786 | <p> </p> |
| 787 | <pre> <a href="#Instruction">Instruction</a> *I = .. ;<br> <a |
| 788 | href="#BasicBlock">BasicBlock</a> *BB = I->getParent();<br> BB->getInstList().erase(I);<br></pre> |
| 789 | <p><!--_______________________________________________________________________--> </p> |
Joel Stanley | 9dd1ad6 | 2002-09-18 03:17:23 +0000 | [diff] [blame] | 790 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 791 | <h4> |
| 792 | <hr size="1"><a name="schanges_replacing">Replacing an <tt>Instruction</tt> |
| 793 | with another <tt>Value</tt></a></h4> |
| 794 | <ul> |
| 795 | <p><i>Replacing individual instructions</i></p> |
| 796 | <p> Including "<a href="/doxygen/BasicBlockUtils_8h-source.html">llvm/Transforms/Utils/BasicBlockUtils.h</a>" |
| 797 | permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt> |
| 798 | and <tt>ReplaceInstWithInst</tt>. </p> |
| 799 | </ul> |
| 800 | <h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4> |
| 801 | <ul> |
| 802 | <ul> |
| 803 | <li><tt>ReplaceInstWithValue</tt> |
| 804 | <p>This function replaces all uses (within a basic block) of a |
| 805 | given instruction with a value, and then removes the original |
| 806 | instruction. The following example illustrates the replacement of the |
| 807 | result of a particular <tt>AllocaInst</tt> that allocates memory for a |
| 808 | single integer with an null pointer to an integer.</p> |
| 809 | <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,<br> Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre> |
| 810 | </li> |
| 811 | <li><tt>ReplaceInstWithInst</tt> |
| 812 | <p>This function replaces a particular instruction with another |
| 813 | instruction. The following example illustrates the replacement of one <tt>AllocaInst</tt> |
| 814 | with another.</p> |
| 815 | <p> </p> |
| 816 | <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithInst(instToReplace->getParent()->getInstList(), ii,<br> new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt"));<br></pre> |
| 817 | </li> |
| 818 | </ul> |
| 819 | <p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p> |
| 820 | You can use <tt>Value::replaceAllUsesWith</tt> and <tt>User::replaceUsesOfWith</tt> |
| 821 | to change more than one use at a time. See the doxygen documentation |
| 822 | for the <a href="/doxygen/classValue.html">Value Class</a> and <a |
| 823 | href="/doxygen/classUser.html">User Class</a>, respectively, for more |
| 824 | information.<!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out: |
Joel Stanley | 9dd1ad6 | 2002-09-18 03:17:23 +0000 | [diff] [blame] | 825 | include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with: |
| 826 | ReplaceInstWithValue, ReplaceInstWithInst |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 827 | --><!-- *********************************************************************** --> |
| 828 | </ul> |
| 829 | <table width="100%" bgcolor="#330077" border="0" cellpadding="4" |
| 830 | cellspacing="0"> |
| 831 | <tbody> |
| 832 | <tr> |
| 833 | <td align="center"><font color="#eeeeff" size="+2" |
| 834 | face="Georgia,Palatino"><b> <a name="coreclasses">The Core LLVM Class |
| 835 | Hierarchy Reference </a></b></font></td> |
| 836 | </tr> |
| 837 | </tbody> |
| 838 | </table> |
| 839 | <ul> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 840 | <!-- *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 841 | The Core LLVM classes are the primary means of representing the program |
| 842 | being inspected or transformed. The core LLVM classes are defined in |
| 843 | header files in the <tt>include/llvm/</tt> directory, and implemented in |
| 844 | the <tt>lib/VMCore</tt> directory. |
| 845 | <p><!-- ======================================================================= --> </p> |
| 846 | </ul> |
| 847 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 848 | cellspacing="0"> |
| 849 | <tbody> |
| 850 | <tr> |
| 851 | <td> </td> |
| 852 | <td width="100%"> <font color="#eeeeff" |
| 853 | face="Georgia,Palatino"><b> <a name="Value">The <tt>Value</tt> class</a> </b></font></td> |
| 854 | </tr> |
| 855 | </tbody> |
| 856 | </table> |
| 857 | <ul> |
| 858 | <tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt><br> |
| 859 | doxygen info: <a href="/doxygen/classValue.html">Value Class</a> |
| 860 | <p> The <tt>Value</tt> class is the most important class in the LLVM |
| 861 | Source base. It represents a typed value that may be used (among other |
| 862 | things) as an operand to an instruction. There are many different types |
| 863 | of <tt>Value</tt>s, such as <a href="#Constant"><tt>Constant</tt></a>s,<a |
| 864 | href="#Argument"><tt>Argument</tt></a>s. Even <a href="#Instruction"><tt>Instruction</tt></a>s |
| 865 | and <a href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p> |
| 866 | <p> A particular <tt>Value</tt> may be used many times in the LLVM |
| 867 | representation for a program. For example, an incoming argument to a |
| 868 | function (represented with an instance of the <a href="#Argument">Argument</a> |
| 869 | class) is "used" by every instruction in the function that references |
| 870 | the argument. To keep track of this relationship, the <tt>Value</tt> |
| 871 | class keeps a list of all of the <a href="#User"><tt>User</tt></a>s |
| 872 | that is using it (the <a href="#User"><tt>User</tt></a> class is a base |
| 873 | class for all nodes in the LLVM graph that can refer to <tt>Value</tt>s). |
| 874 | This use list is how LLVM represents def-use information in the |
| 875 | program, and is accessible through the <tt>use_</tt>* methods, shown |
| 876 | below.</p> |
| 877 | <p> Because LLVM is a typed representation, every LLVM <tt>Value</tt> |
| 878 | is typed, and this <a href="#Type">Type</a> is available through the <tt>getType()</tt> |
| 879 | method. In addition, all LLVM values can be named. The "name" of the <tt>Value</tt> |
| 880 | is a symbolic string printed in the LLVM code:</p> |
| 881 | <p> </p> |
| 882 | <pre> %<b>foo</b> = add int 1, 2<br></pre> |
| 883 | <a name="#nameWarning">The name of this instruction is "foo". <b>NOTE</b> |
| 884 | that the name of any value may be missing (an empty string), so names |
| 885 | should <b>ONLY</b> be used for debugging (making the source code easier |
| 886 | to read, debugging printouts), they should not be used to keep track of |
| 887 | values or map between them. For this purpose, use a <tt>std::map</tt> |
| 888 | of pointers to the <tt>Value</tt> itself instead.</a> |
| 889 | <p> One important aspect of LLVM is that there is no distinction |
| 890 | between an SSA variable and the operation that produces it. Because of |
| 891 | this, any reference to the value produced by an instruction (or the |
| 892 | value available as an incoming argument, for example) is represented as |
| 893 | a direct pointer to the class that represents this value. Although |
| 894 | this may take some getting used to, it simplifies the representation |
| 895 | and makes it easier to manipulate.</p> |
| 896 | <p><!-- _______________________________________________________________________ --> </p> |
| 897 | </ul> |
| 898 | <h4> |
| 899 | <hr size="1"><a name="m_Value">Important Public Members of the <tt>Value</tt> |
| 900 | class</a></h4> |
| 901 | <ul> |
| 902 | <li><tt>Value::use_iterator</tt> - Typedef for iterator over the |
| 903 | use-list<br> |
| 904 | <tt>Value::use_const_iterator</tt> - Typedef for const_iterator over |
| 905 | the use-list<br> |
| 906 | <tt>unsigned use_size()</tt> - Returns the number of users of the |
| 907 | value.<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 908 | <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] | 909 | <tt>use_iterator use_begin()</tt> - Get an iterator to the start of |
| 910 | the use-list.<br> |
| 911 | <tt>use_iterator use_end()</tt> - Get an iterator to the end of the |
| 912 | use-list.<br> |
| 913 | <tt><a href="#User">User</a> *use_back()</tt> - Returns the last |
| 914 | element in the list. |
| 915 | <p> These methods are the interface to access the def-use |
| 916 | information in LLVM. As with all other iterators in LLVM, the naming |
| 917 | conventions follow the conventions defined by the <a href="#stl">STL</a>.</p> |
| 918 | <p> </p> |
| 919 | </li> |
| 920 | <li><tt><a href="#Type">Type</a> *getType() const</tt> |
| 921 | <p> This method returns the Type of the Value. </p> |
| 922 | </li> |
| 923 | <li><tt>bool hasName() const</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 924 | <tt>std::string getName() const</tt><br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 925 | <tt>void setName(const std::string &Name)</tt> |
| 926 | <p> This family of methods is used to access and assign a name to a <tt>Value</tt>, |
| 927 | be aware of the <a href="#nameWarning">precaution above</a>.</p> |
| 928 | <p> </p> |
| 929 | </li> |
| 930 | <li><tt>void replaceAllUsesWith(Value *V)</tt> |
| 931 | <p> This method traverses the use list of a <tt>Value</tt> changing |
| 932 | all <a href="#User"><tt>User</tt>s</a> of the current value to refer to "<tt>V</tt>" |
| 933 | instead. For example, if you detect that an instruction always |
| 934 | produces a constant value (for example through constant folding), you |
| 935 | can replace all uses of the instruction with the constant like this:</p> |
| 936 | <p> </p> |
| 937 | <pre> Inst->replaceAllUsesWith(ConstVal);<br></pre> |
| 938 | <p><!-- ======================================================================= --> </p> |
| 939 | </li> |
| 940 | </ul> |
| 941 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 942 | cellspacing="0"> |
| 943 | <tbody> |
| 944 | <tr> |
| 945 | <td> </td> |
| 946 | <td width="100%"> <font color="#eeeeff" |
| 947 | face="Georgia,Palatino"><b> <a name="User">The <tt>User</tt> class</a> </b></font></td> |
| 948 | </tr> |
| 949 | </tbody> |
| 950 | </table> |
| 951 | <ul> |
| 952 | <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] | 953 | doxygen info: <a href="/doxygen/classUser.html">User Class</a><br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 954 | Superclass: <a href="#Value"><tt>Value</tt></a> |
| 955 | <p> The <tt>User</tt> class is the common base class of all LLVM nodes |
| 956 | that may refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a |
| 957 | list of "Operands" that are all of the <a href="#Value"><tt>Value</tt></a>s |
| 958 | that the User is referring to. The <tt>User</tt> class itself is a |
| 959 | subclass of <tt>Value</tt>.</p> |
| 960 | <p> The operands of a <tt>User</tt> point directly to the LLVM <a |
| 961 | href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses |
| 962 | Static Single Assignment (SSA) form, there can only be one definition |
| 963 | referred to, allowing this direct connection. This connection provides |
| 964 | the use-def information in LLVM.</p> |
| 965 | <p><!-- _______________________________________________________________________ --> </p> |
| 966 | </ul> |
| 967 | <h4> |
| 968 | <hr size="1"><a name="m_User">Important Public Members of the <tt>User</tt> |
| 969 | class</a></h4> |
| 970 | <ul> |
| 971 | The <tt>User</tt> class exposes the operand list in two ways: through |
| 972 | an index access interface and through an iterator based interface. |
| 973 | <p> </p> |
| 974 | <li><tt>Value *getOperand(unsigned i)</tt><br> |
| 975 | <tt>unsigned getNumOperands()</tt> |
| 976 | <p> These two methods expose the operands of the <tt>User</tt> in a |
| 977 | convenient form for direct access.</p> |
| 978 | <p> </p> |
| 979 | </li> |
| 980 | <li><tt>User::op_iterator</tt> - Typedef for iterator over the operand |
| 981 | list<br> |
| 982 | <tt>User::op_const_iterator</tt> <tt>use_iterator op_begin()</tt> - |
| 983 | Get an iterator to the start of the operand list.<br> |
| 984 | <tt>use_iterator op_end()</tt> - Get an iterator to the end of the |
| 985 | operand list. |
| 986 | <p> Together, these methods make up the iterator based interface to |
| 987 | the operands of a <tt>User</tt>.</p> |
| 988 | <p><!-- ======================================================================= --> </p> |
| 989 | </li> |
| 990 | </ul> |
| 991 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 992 | cellspacing="0"> |
| 993 | <tbody> |
| 994 | <tr> |
| 995 | <td> </td> |
| 996 | <td width="100%"> <font color="#eeeeff" |
| 997 | face="Georgia,Palatino"><b> <a name="Instruction">The <tt>Instruction</tt> |
| 998 | class</a> </b></font></td> |
| 999 | </tr> |
| 1000 | </tbody> |
| 1001 | </table> |
| 1002 | <ul> |
| 1003 | <tt>#include "</tt><tt><a href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt><br> |
| 1004 | doxygen info: <a href="/doxygen/classInstruction.html">Instruction |
| 1005 | Class</a><br> |
| 1006 | Superclasses: <a href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a> |
| 1007 | <p> The <tt>Instruction</tt> class is the common base class for all |
| 1008 | LLVM instructions. It provides only a few methods, but is a very |
| 1009 | commonly used class. The primary data tracked by the <tt>Instruction</tt> |
| 1010 | class itself is the opcode (instruction type) and the parent <a |
| 1011 | href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is |
| 1012 | embedded into. To represent a specific type of instruction, one of many |
| 1013 | subclasses of <tt>Instruction</tt> are used.</p> |
| 1014 | <p> Because the <tt>Instruction</tt> class subclasses the <a |
| 1015 | href="#User"><tt>User</tt></a> class, its operands can be accessed in |
| 1016 | the same way as for other <a href="#User"><tt>User</tt></a>s (with the <tt>getOperand()</tt>/<tt>getNumOperands()</tt> |
| 1017 | and <tt>op_begin()</tt>/<tt>op_end()</tt> methods).</p> |
| 1018 | <p> An important file for the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> |
| 1019 | file. This file contains some meta-data about the various different |
| 1020 | types of instructions in LLVM. It describes the enum values that are |
| 1021 | used as opcodes (for example <tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), |
| 1022 | as well as the concrete sub-classes of <tt>Instruction</tt> that |
| 1023 | implement the instruction (for example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> |
| 1024 | and <tt><a href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, |
| 1025 | the use of macros in this file confuses doxygen, so these enum values |
| 1026 | don't show up correctly in the <a href="/doxygen/classInstruction.html">doxygen |
| 1027 | output</a>.</p> |
| 1028 | <p><!-- _______________________________________________________________________ --> </p> |
| 1029 | </ul> |
| 1030 | <h4> |
| 1031 | <hr size="1"><a name="m_Instruction">Important Public Members of the <tt>Instruction</tt> |
| 1032 | class</a></h4> |
| 1033 | <ul> |
| 1034 | <li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt> |
| 1035 | <p> Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that |
| 1036 | this <tt>Instruction</tt> is embedded into.</p> |
| 1037 | <p> </p> |
| 1038 | </li> |
| 1039 | <li><tt>bool mayWriteToMemory()</tt> |
| 1040 | <p> Returns true if the instruction writes to memory, i.e. it is a <tt>call</tt>,<tt>free</tt>,<tt>invoke</tt>, |
| 1041 | or <tt>store</tt>.</p> |
| 1042 | <p> </p> |
| 1043 | </li> |
| 1044 | <li><tt>unsigned getOpcode()</tt> |
| 1045 | <p> Returns the opcode for the <tt>Instruction</tt>.</p> |
| 1046 | <p> </p> |
| 1047 | </li> |
| 1048 | <li><tt><a href="#Instruction">Instruction</a> *clone() const</tt> |
| 1049 | <p> Returns another instance of the specified instruction, identical |
| 1050 | in all ways to the original except that the instruction has no parent |
| 1051 | (ie it's not embedded into a <a href="#BasicBlock"><tt>BasicBlock</tt></a>), |
| 1052 | and it has no name</p> |
| 1053 | </li> |
| 1054 | </ul> |
| 1055 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1056 | cellspacing="0"> |
| 1057 | <tbody> |
| 1058 | <tr> |
| 1059 | <td> </td> |
| 1060 | <td width="100%"> <font color="#eeeeff" |
| 1061 | face="Georgia,Palatino"><b> <a name="BasicBlock">The <tt>BasicBlock</tt> |
| 1062 | class</a> </b></font></td> |
| 1063 | </tr> |
| 1064 | </tbody> |
| 1065 | </table> |
| 1066 | <ul> |
| 1067 | <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] | 1068 | doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1069 | Superclass: <a href="#Value"><tt>Value</tt></a> |
| 1070 | <p> This class represents a single entry multiple exit section of the |
| 1071 | code, commonly known as a basic block by the compiler community. The <tt>BasicBlock</tt> |
| 1072 | class maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, |
| 1073 | which form the body of the block. Matching the language definition, |
| 1074 | the last element of this list of instructions is always a terminator |
| 1075 | instruction (a subclass of the <a href="#TerminatorInst"><tt>TerminatorInst</tt></a> |
| 1076 | class).</p> |
| 1077 | <p> In addition to tracking the list of instructions that make up the |
| 1078 | block, the <tt>BasicBlock</tt> class also keeps track of the <a |
| 1079 | href="#Function"><tt>Function</tt></a> that it is embedded into.</p> |
| 1080 | <p> Note that <tt>BasicBlock</tt>s themselves are <a href="#Value"><tt>Value</tt></a>s, |
| 1081 | because they are referenced by instructions like branches and can go in |
| 1082 | the switch tables. <tt>BasicBlock</tt>s have type <tt>label</tt>.</p> |
| 1083 | <p><!-- _______________________________________________________________________ --> </p> |
| 1084 | </ul> |
| 1085 | <h4> |
| 1086 | <hr size="1"><a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt> |
| 1087 | class</a></h4> |
| 1088 | <ul> |
| 1089 | <li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a |
| 1090 | href="#Function">Function</a> *Parent = 0)</tt> |
| 1091 | <p> The <tt>BasicBlock</tt> constructor is used to create new basic |
| 1092 | blocks for insertion into a function. The constructor optionally takes |
| 1093 | a name for the new block, and a <a href="#Function"><tt>Function</tt></a> |
| 1094 | to insert it into. If the <tt>Parent</tt> parameter is specified, the |
| 1095 | new <tt>BasicBlock</tt> is automatically inserted at the end of the |
| 1096 | specified <a href="#Function"><tt>Function</tt></a>, if not specified, |
| 1097 | the BasicBlock must be manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p> |
| 1098 | <p> </p> |
| 1099 | </li> |
| 1100 | <li><tt>BasicBlock::iterator</tt> - Typedef for instruction list |
| 1101 | iterator<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1102 | <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1103 | <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,<tt>size()</tt>,<tt>empty()</tt>,<tt>rbegin()</tt>,<tt>rend() |
| 1104 | - </tt>STL style functions for accessing the instruction list. |
| 1105 | <p> These methods and typedefs are forwarding functions that have |
| 1106 | the same semantics as the standard library methods of the same names. |
| 1107 | These methods expose the underlying instruction list of a basic block in |
| 1108 | a way that is easy to manipulate. To get the full complement of |
| 1109 | container operations (including operations to update the list), you must |
| 1110 | use the <tt>getInstList()</tt> method.</p> |
| 1111 | <p> </p> |
| 1112 | </li> |
| 1113 | <li><tt>BasicBlock::InstListType &getInstList()</tt> |
| 1114 | <p> This method is used to get access to the underlying container |
| 1115 | that actually holds the Instructions. This method must be used when |
| 1116 | there isn't a forwarding function in the <tt>BasicBlock</tt> class for |
| 1117 | the operation that you would like to perform. Because there are no |
| 1118 | forwarding functions for "updating" operations, you need to use this if |
| 1119 | you want to update the contents of a <tt>BasicBlock</tt>.</p> |
| 1120 | <p> </p> |
| 1121 | </li> |
| 1122 | <li><tt><a href="#Function">Function</a> *getParent()</tt> |
| 1123 | <p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> |
| 1124 | the block is embedded into, or a null pointer if it is homeless.</p> |
| 1125 | <p> </p> |
| 1126 | </li> |
| 1127 | <li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt> |
| 1128 | <p> Returns a pointer to the terminator instruction that appears at |
| 1129 | the end of the <tt>BasicBlock</tt>. If there is no terminator |
| 1130 | instruction, or if the last instruction in the block is not a |
| 1131 | terminator, then a null pointer is returned.</p> |
| 1132 | <p><!-- ======================================================================= --> </p> |
| 1133 | </li> |
| 1134 | </ul> |
| 1135 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1136 | cellspacing="0"> |
| 1137 | <tbody> |
| 1138 | <tr> |
| 1139 | <td> </td> |
| 1140 | <td width="100%"> <font color="#eeeeff" |
| 1141 | face="Georgia,Palatino"><b> <a name="GlobalValue">The <tt>GlobalValue</tt> |
| 1142 | class</a> </b></font></td> |
| 1143 | </tr> |
| 1144 | </tbody> |
| 1145 | </table> |
| 1146 | <ul> |
| 1147 | <tt>#include "<a href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br> |
| 1148 | doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue |
| 1149 | Class</a><br> |
| 1150 | Superclasses: <a href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a> |
| 1151 | <p> Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s |
| 1152 | or <a href="#Function"><tt>Function</tt></a>s) are the only LLVM |
| 1153 | values that are visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s. |
| 1154 | Because they are visible at global scope, they are also subject to |
| 1155 | linking with other globals defined in different translation units. To |
| 1156 | control the linking process, <tt>GlobalValue</tt>s know their linkage |
| 1157 | rules. Specifically, <tt>GlobalValue</tt>s know whether they have |
| 1158 | internal or external linkage, as defined by the <span |
| 1159 | style="font-family: monospace;">LinkageTypes</span> enumerator.</p> |
| 1160 | <p> If a <tt>GlobalValue</tt> has internal linkage (equivalent to |
| 1161 | being <tt>static</tt> in C), it is not visible to code outside the |
| 1162 | current translation unit, and does not participate in linking. If it |
| 1163 | has external linkage, it is visible to external code, and does |
| 1164 | participate in linking. In addition to linkage information, <tt>GlobalValue</tt>s |
| 1165 | keep track of which <a href="#Module"><tt>Module</tt></a> they are |
| 1166 | currently part of.</p> |
| 1167 | <p> Because <tt>GlobalValue</tt>s are memory objects, they are always |
| 1168 | referred to by their <span style="font-weight: bold;">address</span><span |
| 1169 | style="font-weight: bold;">.</span> As such, the <a href="#Type"><tt>Type</tt></a> |
| 1170 | of a global is always a pointer to its contents. It is important to |
| 1171 | remember this when using the <span style="font-family: monospace;">GetElementPtrInst</span> |
| 1172 | instruction because this pointer must be dereferenced first. For |
| 1173 | example, if you have a <span style="font-family: monospace;">GlobalVariable</span> |
| 1174 | (a subclass of <span style="font-family: monospace;">GlobalValue)</span> |
| 1175 | that is an array of 24 ints, type <span style="font-family: monospace;">[24 |
| 1176 | x int]</span>, then the <span style="font-family: monospace;">GlobalVariable</span> |
| 1177 | is a pointer to that array. Although the address of the first element of |
| 1178 | this array and the value of the <span style="font-family: monospace;">GlobalVariable</span> |
| 1179 | are the same, they have different types. The <span |
| 1180 | style="font-family: monospace;">GlobalVariable</span>'s type is <span |
| 1181 | style="font-family: monospace;">[24 x int]</span>. The first element's |
| 1182 | type is <span style="font-family: monospace;">int.</span> Because of |
| 1183 | this, accessing a global value requires you to dereference the pointer |
| 1184 | with <span style="font-family: monospace;">GetElementPtrInst</span> |
| 1185 | first, then its elements can be accessed. This is explained in |
| 1186 | the <a href="LangRef.html#globalvars">LLVM Language Reference Manual</a>.</p> |
| 1187 | <p><!-- _______________________________________________________________________ --> </p> |
| 1188 | </ul> |
| 1189 | <h4> |
| 1190 | <hr size="1"><a name="m_GlobalValue">Important Public Members of the <tt>GlobalValue</tt> |
| 1191 | class</a></h4> |
| 1192 | <ul> |
| 1193 | <li><tt>bool hasInternalLinkage() const</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1194 | <tt>bool hasExternalLinkage() const</tt><br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1195 | <tt>void setInternalLinkage(bool HasInternalLinkage)</tt> |
| 1196 | <p> These methods manipulate the linkage characteristics of the <tt>GlobalValue</tt>.</p> |
| 1197 | <p> </p> |
| 1198 | </li> |
| 1199 | <li><tt><a href="#Module">Module</a> *getParent()</tt> |
| 1200 | <p> This returns the <a href="#Module"><tt>Module</tt></a> that the |
| 1201 | GlobalValue is currently embedded into.</p> |
| 1202 | <p><!-- ======================================================================= --> </p> |
| 1203 | </li> |
| 1204 | </ul> |
| 1205 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1206 | cellspacing="0"> |
| 1207 | <tbody> |
| 1208 | <tr> |
| 1209 | <td> </td> |
| 1210 | <td width="100%"> <font color="#eeeeff" |
| 1211 | face="Georgia,Palatino"><b> <a name="Function">The <tt>Function</tt> |
| 1212 | class</a> </b></font></td> |
| 1213 | </tr> |
| 1214 | </tbody> |
| 1215 | </table> |
| 1216 | <ul> |
| 1217 | <tt>#include "<a href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1218 | doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br> |
| 1219 | Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1220 | href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a> |
| 1221 | <p> The <tt>Function</tt> class represents a single procedure in LLVM. |
| 1222 | It is actually one of the more complex classes in the LLVM heirarchy |
| 1223 | because it must keep track of a large amount of data. The <tt>Function</tt> |
| 1224 | class keeps track of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, |
| 1225 | a list of formal <a href="#Argument"><tt>Argument</tt></a>s, and a <a |
| 1226 | href="#SymbolTable"><tt>SymbolTable</tt></a>.</p> |
| 1227 | <p> The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the |
| 1228 | most commonly used part of <tt>Function</tt> objects. The list imposes |
| 1229 | an implicit ordering of the blocks in the function, which indicate how |
| 1230 | the code will be layed out by the backend. Additionally, the first <a |
| 1231 | href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node |
| 1232 | for the <tt>Function</tt>. It is not legal in LLVM to explicitly |
| 1233 | branch to this initial block. There are no implicit exit nodes, and in |
| 1234 | fact there may be multiple exit nodes from a single <tt>Function</tt>. |
| 1235 | If the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, |
| 1236 | this indicates that the <tt>Function</tt> is actually a function |
| 1237 | declaration: the actual body of the function hasn't been linked in yet.</p> |
| 1238 | <p> In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, |
| 1239 | the <tt>Function</tt> class also keeps track of the list of formal <a |
| 1240 | href="#Argument"><tt>Argument</tt></a>s that the function receives. |
| 1241 | This container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a> |
| 1242 | nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list |
| 1243 | does for the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.</p> |
| 1244 | <p> The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very |
| 1245 | rarely used LLVM feature that is only used when you have to look up a |
| 1246 | value by name. Aside from that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1247 | is used internally to make sure that there are not conflicts between the |
| 1248 | names of <a href="#Instruction"><tt>Instruction</tt></a>s, <a |
| 1249 | href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a href="#Argument"><tt>Argument</tt></a>s |
| 1250 | in the function body.</p> |
| 1251 | <p><!-- _______________________________________________________________________ --> </p> |
| 1252 | </ul> |
| 1253 | <h4> |
| 1254 | <hr size="1"><a name="m_Function">Important Public Members of the <tt>Function</tt> |
| 1255 | class</a></h4> |
| 1256 | <ul> |
| 1257 | <li><tt>Function(const </tt><tt><a href="#FunctionType">FunctionType</a> |
| 1258 | *Ty, bool isInternal, const std::string &N = "", Module* Parent = 0)</tt> |
| 1259 | <p> Constructor used when you need to create new <tt>Function</tt>s |
| 1260 | to add the the program. The constructor must specify the type of the |
| 1261 | function to create and whether or not it should start out with internal |
| 1262 | or external linkage. The <a href="#FunctionType" |
| 1263 | style="font-family: monospace;">FunctionType</a> argument specifies the |
| 1264 | formal arguments and return value for the function. The same <a |
| 1265 | href="#FunctionTypel" style="font-family: monospace;">FunctionType</a> |
| 1266 | value can be used to create multiple functions. The <span |
| 1267 | style="font-family: monospace;">Parent</span> argument specifies the |
| 1268 | Module in which the function is defined. If this argument is provided, |
| 1269 | the function will automatically be inserted into that module's list of |
| 1270 | functions.</p> |
| 1271 | <p> </p> |
| 1272 | </li> |
| 1273 | <li><tt>bool isExternal()</tt> |
| 1274 | <p> Return whether or not the <tt>Function</tt> has a body defined. |
| 1275 | If the function is "external", it does not have a body, and thus must be |
| 1276 | resolved by linking with a function defined in a different translation |
| 1277 | unit.</p> |
| 1278 | <p> </p> |
| 1279 | </li> |
| 1280 | <li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1281 | <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1282 | <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,<tt>size()</tt>,<tt>empty()</tt>,<tt>rbegin()</tt>,<tt>rend()</tt> |
| 1283 | <p> These are forwarding methods that make it easy to access the |
| 1284 | contents of a <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a> |
| 1285 | list.</p> |
| 1286 | <p> </p> |
| 1287 | </li> |
| 1288 | <li><tt>Function::BasicBlockListType &getBasicBlockList()</tt> |
| 1289 | <p> Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. |
| 1290 | This is necessary to use when you need to update the list or perform a |
| 1291 | complex action that doesn't have a forwarding method.</p> |
| 1292 | <p> </p> |
| 1293 | </li> |
| 1294 | <li><tt>Function::aiterator</tt> - Typedef for the argument list |
| 1295 | iterator<br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1296 | <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1297 | <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,<tt>asize()</tt>,<tt>aempty()</tt>,<tt>arbegin()</tt>,<tt>arend()</tt> |
| 1298 | <p> These are forwarding methods that make it easy to access the |
| 1299 | contents of a <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> |
| 1300 | list.</p> |
| 1301 | <p> </p> |
| 1302 | </li> |
| 1303 | <li><tt>Function::ArgumentListType &getArgumentList()</tt> |
| 1304 | <p> Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. |
| 1305 | This is necessary to use when you need to update the list or perform a |
| 1306 | complex action that doesn't have a forwarding method.</p> |
| 1307 | <p> </p> |
| 1308 | </li> |
| 1309 | <li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryBlock()</tt> |
| 1310 | <p> Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> |
| 1311 | for the function. Because the entry block for the function is always |
| 1312 | the first block, this returns the first block of the <tt>Function</tt>.</p> |
| 1313 | <p> </p> |
| 1314 | </li> |
| 1315 | <li><tt><a href="#Type">Type</a> *getReturnType()</tt><br> |
| 1316 | <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt> |
| 1317 | <p> This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1318 | and returns the return type of the function, or the <a |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1319 | href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.</p> |
| 1320 | <p> </p> |
| 1321 | </li> |
| 1322 | <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt> |
| 1323 | <p> Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1324 | for this <tt>Function</tt>.</p> |
| 1325 | <p><!-- ======================================================================= --> </p> |
| 1326 | </li> |
| 1327 | </ul> |
| 1328 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1329 | cellspacing="0"> |
| 1330 | <tbody> |
| 1331 | <tr> |
| 1332 | <td> </td> |
| 1333 | <td width="100%"> <font color="#eeeeff" |
| 1334 | face="Georgia,Palatino"><b> <a name="GlobalVariable">The <tt>GlobalVariable</tt> |
| 1335 | class</a> </b></font></td> |
| 1336 | </tr> |
| 1337 | </tbody> |
| 1338 | </table> |
| 1339 | <ul> |
| 1340 | <tt>#include "<a href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt><br> |
| 1341 | doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable |
| 1342 | Class</a><br> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1343 | Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1344 | href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a> |
| 1345 | <p> Global variables are represented with the (suprise suprise) <tt>GlobalVariable</tt> |
| 1346 | class. Like functions, <tt>GlobalVariable</tt>s are also subclasses of <a |
| 1347 | href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are always |
| 1348 | referenced by their address (global values must live in memory, so their |
| 1349 | "name" refers to their address). See <a href="#GlobalValue"><span |
| 1350 | style="font-family: monospace;">GlobalValue</span></a> for more on |
| 1351 | this. Global variables may have an initial value (which must be a <a |
| 1352 | href="#Constant"><tt>Constant</tt></a>), and if they have an |
| 1353 | initializer, they may be marked as "constant" themselves (indicating |
| 1354 | that their contents never change at runtime). </p> |
| 1355 | <p><!-- _______________________________________________________________________ --> </p> |
| 1356 | </ul> |
| 1357 | <h4> |
| 1358 | <hr size="1"><a name="m_GlobalVariable">Important Public Members of the <tt>GlobalVariable</tt> |
| 1359 | class</a></h4> |
| 1360 | <ul> |
| 1361 | <li><tt>GlobalVariable(const </tt><tt><a href="#Type">Type</a> *Ty, |
| 1362 | bool isConstant, LinkageTypes& Linkage, <a href="#Constant">Constant</a> |
| 1363 | *Initializer = 0, const std::string &Name = "", Module* Parent = 0)</tt> |
| 1364 | <p> Create a new global variable of the specified type. If <tt>isConstant</tt> |
| 1365 | is true then the global variable will be marked as unchanging for the |
| 1366 | program. The Linkage parameter specifies the type of linkage (internal, |
| 1367 | external, weak, linkonce, appending) for the variable. If the linkage |
| 1368 | is InternalLinkage, WeakLinkage, or LinkOnceLinkage, then the |
| 1369 | resultant global variable will have internal linkage. AppendingLinkage |
| 1370 | concatenates together all instances (in different translation units) of |
| 1371 | the variable into a single variable but is only applicable to arrays. |
| 1372 | See the <a href="LangRef.html#modulestructure">LLVM Language |
| 1373 | Reference</a> for further details on linkage types. Optionally an |
| 1374 | initializer, a name, and the module to put the variable into may be |
| 1375 | specified for the global variable as well.</p> |
| 1376 | <p> </p> |
| 1377 | </li> |
| 1378 | <li><tt>bool isConstant() const</tt> |
| 1379 | <p> Returns true if this is a global variable that is known not to |
| 1380 | be modified at runtime.</p> |
| 1381 | <p> </p> |
| 1382 | </li> |
| 1383 | <li><tt>bool hasInitializer()</tt> |
| 1384 | <p> Returns true if this <tt>GlobalVariable</tt> has an intializer.</p> |
| 1385 | <p> </p> |
| 1386 | </li> |
| 1387 | <li><tt><a href="#Constant">Constant</a> *getInitializer()</tt> |
| 1388 | <p> Returns the intial value for a <tt>GlobalVariable</tt>. It is |
| 1389 | not legal to call this method if there is no initializer.</p> |
| 1390 | <p><!-- ======================================================================= --> </p> |
| 1391 | </li> |
| 1392 | </ul> |
| 1393 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1394 | cellspacing="0"> |
| 1395 | <tbody> |
| 1396 | <tr> |
| 1397 | <td> </td> |
| 1398 | <td width="100%"> <font color="#eeeeff" |
| 1399 | face="Georgia,Palatino"><b> <a name="Module">The <tt>Module</tt> class</a> </b></font></td> |
| 1400 | </tr> |
| 1401 | </tbody> |
| 1402 | </table> |
| 1403 | <ul> |
| 1404 | <tt>#include "<a href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt><br> |
| 1405 | doxygen info: <a href="/doxygen/classModule.html">Module Class</a> |
| 1406 | <p> The <tt>Module</tt> class represents the top level structure |
| 1407 | present in LLVM programs. An LLVM module is effectively either a |
| 1408 | translation unit of the original program or a combination of several |
| 1409 | translation units merged by the linker. The <tt>Module</tt> class keeps |
| 1410 | track of a list of <a href="#Function"><tt>Function</tt></a>s, a list |
| 1411 | of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a |
| 1412 | href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it |
| 1413 | contains a few helpful member functions that try to make common |
| 1414 | operations easy.</p> |
| 1415 | <p><!-- _______________________________________________________________________ --> </p> |
| 1416 | </ul> |
| 1417 | <h4> |
| 1418 | <hr size="1"><a name="m_Module">Important Public Members of the <tt>Module</tt> |
| 1419 | class<span style="font-family: monospace;"></span></a></h4> |
| 1420 | <ul> |
| 1421 | <li><span style="font-family: monospace;">Module::Module( std::string |
| 1422 | name = "" ) </span></li> |
| 1423 | </ul> |
| 1424 | <p style="margin-left: 40px;">Constructing a <a href="#Module">Module</a> |
| 1425 | is easy. You can optionally provide a name for it (probably based on the |
| 1426 | name of the translation unit).</p> |
| 1427 | <ul> |
| 1428 | <li><tt>Module::iterator</tt> - Typedef for function list iterator<br> |
Chris Lattner | 0377de4 | 2002-09-06 14:50:55 +0000 | [diff] [blame] | 1429 | <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1430 | <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,<tt>size()</tt>,<tt>empty()</tt>,<tt>rbegin()</tt>,<tt>rend()</tt> |
| 1431 | <p> These are forwarding methods that make it easy to access the |
| 1432 | contents of a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a> |
| 1433 | list.</p> |
| 1434 | <p> </p> |
| 1435 | </li> |
| 1436 | <li><tt>Module::FunctionListType &getFunctionList()</tt> |
| 1437 | <p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. |
| 1438 | This is necessary to use when you need to update the list or perform a |
| 1439 | complex action that doesn't have a forwarding method.</p> |
| 1440 | <p><!-- Global Variable --> </p> |
| 1441 | <hr size="1"> </li> |
| 1442 | <li><tt>Module::giterator</tt> - Typedef for global variable list |
| 1443 | iterator<br> |
Chris Lattner | 0377de4 | 2002-09-06 14:50:55 +0000 | [diff] [blame] | 1444 | <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1445 | <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,<tt>gsize()</tt>,<tt>gempty()</tt>,<tt>grbegin()</tt>,<tt>grend()</tt> |
| 1446 | <p> These are forwarding methods that make it easy to access the |
| 1447 | contents of a <tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a> |
| 1448 | list.</p> |
| 1449 | <p> </p> |
| 1450 | </li> |
| 1451 | <li><tt>Module::GlobalListType &getGlobalList()</tt> |
| 1452 | <p> Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. |
| 1453 | This is necessary to use when you need to update the list or perform a |
| 1454 | complex action that doesn't have a forwarding method.</p> |
| 1455 | <p><!-- Symbol table stuff --> </p> |
| 1456 | <hr size="1"> </li> |
| 1457 | <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt> |
| 1458 | <p> Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1459 | for this <tt>Module</tt>.</p> |
| 1460 | <p><!-- Convenience methods --> </p> |
| 1461 | <hr size="1"> </li> |
| 1462 | <li><tt><a href="#Function">Function</a> *getFunction(const |
| 1463 | std::string &Name, const <a href="#FunctionType">FunctionType</a> |
| 1464 | *Ty)</tt> |
| 1465 | <p> Look up the specified function in the <tt>Module</tt> <a |
| 1466 | href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, |
| 1467 | return <tt>null</tt>.</p> |
| 1468 | <p> </p> |
| 1469 | </li> |
| 1470 | <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const |
| 1471 | std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt> |
| 1472 | <p> Look up the specified function in the <tt>Module</tt> <a |
| 1473 | href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, |
| 1474 | add an external declaration for the function and return it.</p> |
| 1475 | <p> </p> |
| 1476 | </li> |
| 1477 | <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt> |
| 1478 | <p> If there is at least one entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1479 | for the specified <a href="#Type"><tt>Type</tt></a>, return it. |
| 1480 | Otherwise return the empty string.</p> |
| 1481 | <p> </p> |
| 1482 | </li> |
| 1483 | <li><tt>bool addTypeName(const std::string &Name, const <a |
| 1484 | href="#Type">Type</a> *Ty)</tt> |
| 1485 | <p> Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1486 | mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for |
| 1487 | this name, true is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> |
| 1488 | is not modified.</p> |
| 1489 | <p><!-- ======================================================================= --> </p> |
| 1490 | </li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1491 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1492 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1493 | cellspacing="0"> |
| 1494 | <tbody> |
| 1495 | <tr> |
| 1496 | <td> </td> |
| 1497 | <td width="100%"> <font color="#eeeeff" |
| 1498 | face="Georgia,Palatino"><b> <a name="Constant">The <tt>Constant</tt> |
| 1499 | class and subclasses</a> </b></font></td> |
| 1500 | </tr> |
| 1501 | </tbody> |
| 1502 | </table> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1503 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1504 | Constant represents a base class for different types of constants. It |
| 1505 | is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt, |
| 1506 | ConstantArray etc for representing the various types of Constants. |
| 1507 | <p><!-- _______________________________________________________________________ --> </p> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1508 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1509 | <h4> |
| 1510 | <hr size="1"><a name="m_Value">Important Public Methods</a></h4> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1511 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1512 | <li><tt>bool isConstantExpr()</tt>: Returns true if it is a |
| 1513 | ConstantExpr |
| 1514 | <hr> Important Subclasses of Constant |
| 1515 | <p> </p> |
| 1516 | <ul> |
| 1517 | <li>ConstantSInt : This subclass of Constant represents a signed |
| 1518 | integer constant. |
| 1519 | <ul> |
| 1520 | <li><tt>int64_t getValue() const</tt>: Returns the underlying value of |
| 1521 | this constant. </li> |
| 1522 | </ul> |
| 1523 | </li> |
| 1524 | <li>ConstantUInt : This class represents an unsigned integer. |
| 1525 | <ul> |
| 1526 | <li><tt>uint64_t getValue() const</tt>: Returns the underlying value |
| 1527 | of this constant. </li> |
| 1528 | </ul> |
| 1529 | </li> |
| 1530 | <li>ConstantFP : This class represents a floating point constant. |
| 1531 | <ul> |
| 1532 | <li><tt>double getValue() const</tt>: Returns the underlying value of |
| 1533 | this constant. </li> |
| 1534 | </ul> |
| 1535 | </li> |
| 1536 | <li>ConstantBool : This represents a boolean constant. |
| 1537 | <ul> |
| 1538 | <li><tt>bool getValue() const</tt>: Returns the underlying value of |
| 1539 | this constant. </li> |
| 1540 | </ul> |
| 1541 | </li> |
| 1542 | <li>ConstantArray : This represents a constant array. |
| 1543 | <ul> |
| 1544 | <li><tt>const std::vector<Use> &getValues() const</tt>: |
| 1545 | Returns a Vecotr of component constants that makeup this array. </li> |
| 1546 | </ul> |
| 1547 | </li> |
| 1548 | <li>ConstantStruct : This represents a constant struct. |
| 1549 | <ul> |
| 1550 | <li><tt>const std::vector<Use> &getValues() const</tt>: |
| 1551 | Returns a Vecotr of component constants that makeup this array. </li> |
| 1552 | </ul> |
| 1553 | </li> |
| 1554 | <li>ConstantPointerRef : This represents a constant pointer value |
| 1555 | that is initialized to point to a global value, which lies at a |
| 1556 | constant fixed address. |
| 1557 | <ul> |
| 1558 | <li><tt>GlobalValue *getValue()</tt>: Returns the global |
| 1559 | value to which this pointer is pointing to. </li> |
| 1560 | </ul> |
| 1561 | </li> |
| 1562 | </ul> |
| 1563 | <!-- ======================================================================= --> </li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1564 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1565 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1566 | cellspacing="0"> |
| 1567 | <tbody> |
| 1568 | <tr> |
| 1569 | <td> </td> |
| 1570 | <td width="100%"> <font color="#eeeeff" |
| 1571 | face="Georgia,Palatino"><b> <a name="Type">The <tt>Type</tt> class and |
| 1572 | Derived Types</a> </b></font></td> |
| 1573 | </tr> |
| 1574 | </tbody> |
| 1575 | </table> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1576 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1577 | Type as noted earlier is also a subclass of a Value class. Any |
| 1578 | primitive type (like int, short etc) in LLVM is an instance of Type |
| 1579 | Class. All other types are instances of subclasses of type like |
| 1580 | FunctionType, ArrayType etc. DerivedType is the interface for all such |
| 1581 | dervied types including FunctionType, ArrayType, PointerType, |
| 1582 | StructType. Types can have names. They can be recursive (StructType). |
| 1583 | There exists exactly one instance of any type structure at a time. This |
| 1584 | allows using pointer equality of Type *s for comparing types.<!-- _______________________________________________________________________ --> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1585 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1586 | <h4> |
| 1587 | <hr size="1"><a name="m_Value">Important Public Methods</a></h4> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1588 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1589 | <li><tt>PrimitiveID getPrimitiveID() const</tt>: Returns the base |
| 1590 | type of the type. </li> |
| 1591 | <li><tt> bool isSigned() const</tt>: Returns whether an integral |
| 1592 | numeric type is signed. This is true for SByteTy, ShortTy, IntTy, |
| 1593 | LongTy. Note that this is not true for Float and Double. </li> |
| 1594 | <li><tt>bool isUnsigned() const</tt>: Returns whether a numeric type |
| 1595 | is unsigned. This is not quite the complement of isSigned... nonnumeric |
| 1596 | types return false as they do with isSigned. This returns true for |
| 1597 | UByteTy, UShortTy, UIntTy, and ULongTy. </li> |
| 1598 | <li><tt> bool isInteger() const</tt>: Equilivent to isSigned() || |
| 1599 | isUnsigned(), but with only a single virtual function invocation. </li> |
| 1600 | <li><tt>bool isIntegral() const</tt>: Returns true if this is an |
| 1601 | integral type, which is either Bool type or one of the Integer types. </li> |
| 1602 | <li><tt>bool isFloatingPoint()</tt>: Return true if this is one of |
| 1603 | the two floating point types. </li> |
| 1604 | <li><tt>bool isRecursive() const</tt>: Returns rue if the type graph |
| 1605 | contains a cycle. </li> |
| 1606 | <li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return |
| 1607 | true if this type can be converted to 'Ty' without any reinterpretation |
| 1608 | of bits. For example, uint to int. </li> |
| 1609 | <li><tt>bool isPrimitiveType() const</tt>: Returns true if it is a |
| 1610 | primitive type. </li> |
| 1611 | <li><tt>bool isDerivedType() const</tt>: Returns true if it is a |
| 1612 | derived type. </li> |
| 1613 | <li><tt>const Type * getContainedType (unsigned i) const</tt>: This |
| 1614 | method is used to implement the type iterator. For derived types, this |
| 1615 | returns the types 'contained' in the derived type, returning 0 when 'i' |
| 1616 | becomes invalid. This allows the user to iterate over the types in a |
| 1617 | struct, for example, really easily. </li> |
| 1618 | <li><tt>unsigned getNumContainedTypes() const</tt>: Return the number |
| 1619 | of types in the derived type. |
| 1620 | <p> </p> |
| 1621 | <hr> Derived Types |
| 1622 | <p> </p> |
| 1623 | <ul> |
| 1624 | <li>SequentialType : This is subclassed by ArrayType and |
| 1625 | PointerType |
| 1626 | <ul> |
| 1627 | <li><tt>const Type * getElementType() const</tt>: Returns the type of |
| 1628 | each of the elements in the sequential type. </li> |
| 1629 | </ul> |
| 1630 | </li> |
| 1631 | <li>ArrayType : This is a subclass of SequentialType and defines |
| 1632 | interface for array types. |
| 1633 | <ul> |
| 1634 | <li><tt>unsigned getNumElements() const</tt>: Returns the number of |
| 1635 | elements in the array. </li> |
| 1636 | </ul> |
| 1637 | </li> |
| 1638 | <li>PointerType : Subclass of SequentialType for pointer types. </li> |
| 1639 | <li>StructType : subclass of DerivedTypes for struct types </li> |
| 1640 | <li>FunctionType : subclass of DerivedTypes for function types. |
| 1641 | <ul> |
| 1642 | <li><tt>bool isVarArg() const</tt>: Returns true if its a vararg |
| 1643 | function </li> |
| 1644 | <li><tt> const Type * getReturnType() const</tt>: Returns the |
| 1645 | return type of the function. </li> |
| 1646 | <li><tt> const ParamTypes &getParamTypes() const</tt>: |
| 1647 | Returns a vector of parameter types. </li> |
| 1648 | <li><tt>const Type * getParamType (unsigned i)</tt>: Returns |
| 1649 | the type of the ith parameter. </li> |
| 1650 | <li><tt> const unsigned getNumParams() const</tt>: Returns the |
| 1651 | number of formal parameters. </li> |
| 1652 | </ul> |
| 1653 | </li> |
| 1654 | </ul> |
| 1655 | <!-- ======================================================================= --> </li> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1656 | </ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1657 | <table width="100%" bgcolor="#441188" border="0" cellpadding="4" |
| 1658 | cellspacing="0"> |
| 1659 | <tbody> |
| 1660 | <tr> |
| 1661 | <td> </td> |
| 1662 | <td width="100%"> <font color="#eeeeff" |
| 1663 | face="Georgia,Palatino"><b> <a name="Argument">The <tt>Argument</tt> |
| 1664 | class</a> </b></font></td> |
| 1665 | </tr> |
| 1666 | </tbody> |
| 1667 | </table> |
Chris Lattner | c75ff9a | 2002-10-01 23:17:09 +0000 | [diff] [blame] | 1668 | <ul> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1669 | This subclass of Value defines the interface for incoming formal |
| 1670 | arguments to a function. A Function maitanis a list of its formal |
| 1671 | arguments. An argument has a pointer to the parent Function.<!-- *********************************************************************** --> |
Chris Lattner | 9355b47 | 2002-09-06 02:50:58 +0000 | [diff] [blame] | 1672 | </ul> |
| 1673 | <!-- *********************************************************************** --> |
Chris Lattner | 261efe9 | 2003-11-25 01:02:51 +0000 | [diff] [blame] | 1674 | <hr><font size-1=""> |
| 1675 | <address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> |
| 1676 | and <a href="mailto:sabre@nondot.org">Chris Lattner</a></address> |
| 1677 | </font><font size-1=""><a href="http://llvm.cs.uiuc.edu">The LLVM |
| 1678 | Compiler Infrastructure</a> <br> |
| 1679 | <!-- Created: Tue Aug 6 15:00:33 CDT 2002 --><!-- hhmts start --> Last |
| 1680 | modified: Fri Nov 7 13:24:22 CST 2003<!-- hhmts end --> </font> |
| 1681 | </body> |
| 1682 | </html> |