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6 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
7 <tr><td> <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM Programmer's Manual</b></font></td>
11 <li><a href="#introduction">Introduction</a>
12 <li><a href="#general">General Information</a>
14 <li><a href="#stl">The C++ Standard Template Library</a>
15 <li><a href="#isa">The <tt>isa<></tt>, <tt>cast<></tt> and
16 <tt>dyn_cast<></tt> templates</a>
18 <li><a href="#common">Helpful Hints for Common Operations</a>
20 <li><a href="#inspection">Basic Inspection and Traversal Routines</a>
22 <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
23 in a <tt>Function</tt></a>
24 <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
25 in a <tt>BasicBlock</tt></a>
26 <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
27 in a <tt>Function</tt></a>
28 <li><a href="#iterate_convert">Turning an iterator into a class
30 <li><a href="#iterate_complex">Finding call sites: a more complex
32 <li><a href="#iterate_chains">Iterating over def-use & use-def
35 <li><a href="#simplechanges">Making simple changes</a>
37 <li>Creating and inserting new <tt>Instruction</tt>s
38 <li>Deleting <tt>Instruction</tt>s
39 <li>Replacing an <tt>Instruction</tt> with another <tt>Value</tt>
42 <li>Working with the Control Flow Graph
44 <li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
50 <li>The general graph API
51 <li>The <tt>InstVisitor</tt> template
53 <li>The <tt>Statistic</tt> template
57 <li>Useful related topics
59 <li>The <tt>-time-passes</tt> option
60 <li>How to use the LLVM Makefile system
61 <li>How to write a regression test
66 <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
68 <li><a href="#Value">The <tt>Value</tt> class</a>
70 <li><a href="#User">The <tt>User</tt> class</a>
72 <li><a href="#Instruction">The <tt>Instruction</tt> class</a>
76 <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
78 <li><a href="#BasicBlock">The <tt>BasicBlock</tt> class</a>
79 <li><a href="#Function">The <tt>Function</tt> class</a>
80 <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a>
82 <li><a href="#Module">The <tt>Module</tt> class</a>
83 <li><a href="#Constant">The <tt>Constant</tt> class</a>
89 <li><a href="#Type">The <tt>Type</tt> class</a>
90 <li><a href="#Argument">The <tt>Argument</tt> class</a>
92 <li>The <tt>SymbolTable</tt> class
93 <li>The <tt>ilist</tt> and <tt>iplist</tt> classes
95 <li>Creating, inserting, moving and deleting from LLVM lists
97 <li>Important iterator invalidation semantics to be aware of
100 <p><b>Written by <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>
101 <a href="mailto:sabre@nondot.org">Chris Lattner</a>, and
102 <a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b><p>
106 <!-- *********************************************************************** -->
107 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
108 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
109 <a name="introduction">Introduction
110 </b></font></td></tr></table><ul>
111 <!-- *********************************************************************** -->
113 This document is meant to highlight some of the important classes and interfaces
114 available in the LLVM source-base. This manual is not intended to explain what
115 LLVM is, how it works, and what LLVM code looks like. It assumes that you know
116 the basics of LLVM and are interested in writing transformations or otherwise
117 analyzing or manipulating the code.<p>
119 This document should get you oriented so that you can find your way in the
120 continuously growing source code that makes up the LLVM infrastructure. Note
121 that this manual is not intended to serve as a replacement for reading the
122 source code, so if you think there should be a method in one of these classes to
123 do something, but it's not listed, check the source. Links to the <a
124 href="/doxygen/">doxygen</a> sources are provided to make this as easy as
127 The first section of this document describes general information that is useful
128 to know when working in the LLVM infrastructure, and the second describes the
129 Core LLVM classes. In the future this manual will be extended with information
130 describing how to use extension libraries, such as dominator information, CFG
131 traversal routines, and useful utilities like the <tt><a
132 href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.<p>
135 <!-- *********************************************************************** -->
136 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
137 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
138 <a name="general">General Information
139 </b></font></td></tr></table><ul>
140 <!-- *********************************************************************** -->
142 This section contains general information that is useful if you are working in
143 the LLVM source-base, but that isn't specific to any particular API.<p>
146 <!-- ======================================================================= -->
147 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
148 <tr><td> </td><td width="100%">
149 <font color="#EEEEFF" face="Georgia,Palatino"><b>
150 <a name="stl">The C++ Standard Template Library</a>
151 </b></font></td></tr></table><ul>
153 LLVM makes heavy use of the C++ Standard Template Library (STL), perhaps much
154 more than you are used to, or have seen before. Because of this, you might want
155 to do a little background reading in the techniques used and capabilities of the
156 library. There are many good pages that discuss the STL, and several books on
157 the subject that you can get, so it will not be discussed in this document.<p>
159 Here are some useful links:<p>
161 <li><a href="http://www.dinkumware.com/htm_cpl/index.html">Dinkumware C++
162 Library reference</a> - an excellent reference for the STL and other parts of
163 the standard C++ library.<br>
165 <li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
168 <li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
170 href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
173 <li><a href="http://www.research.att.com/~bs/C++.html">Bjarne Stroustrup's C++
178 You are also encouraged to take a look at the <a
179 href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
180 to write maintainable code more than where to put your curly braces.<p>
183 <!-- ======================================================================= -->
184 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
185 <tr><td> </td><td width="100%">
186 <font color="#EEEEFF" face="Georgia,Palatino"><b>
187 <a name="isa">The isa<>, cast<> and dyn_cast<> templates</a>
188 </b></font></td></tr></table><ul>
190 The LLVM source-base makes extensive use of a custom form of RTTI. These
191 templates have many similarities to the C++ <tt>dynamic_cast<></tt>
192 operator, but they don't have some drawbacks (primarily stemming from the fact
193 that <tt>dynamic_cast<></tt> only works on classes that have a v-table).
194 Because they are used so often, you must know what they do and how they work.
195 All of these templates are defined in the <a
196 href="/doxygen/Casting_8h-source.html"><tt>Support/Casting.h</tt></a> file (note
197 that you very rarely have to include this file directly).<p>
201 <dt><tt>isa<></tt>:
203 <dd>The <tt>isa<></tt> operator works exactly like the Java
204 "<tt>instanceof</tt>" operator. It returns true or false depending on whether a
205 reference or pointer points to an instance of the specified class. This can be
206 very useful for constraint checking of various sorts (example below).<p>
209 <dt><tt>cast<></tt>:
211 <dd>The <tt>cast<></tt> operator is a "checked cast" operation. It
212 converts a pointer or reference from a base class to a derived cast, causing an
213 assertion failure if it is not really an instance of the right type. This
214 should be used in cases where you have some information that makes you believe
215 that something is of the right type. An example of the <tt>isa<></tt> and
216 <tt>cast<></tt> template is:<p>
219 static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const Loop *L) {
220 if (isa<<a href="#Constant">Constant</a>>(V) || isa<<a href="#Argument">Argument</a>>(V) || isa<<a href="#GlobalValue">GlobalValue</a>>(V))
223 <i>// Otherwise, it must be an instruction...</i>
224 return !L->contains(cast<<a href="#Instruction">Instruction</a>>(V)->getParent());
227 Note that you should <b>not</b> use an <tt>isa<></tt> test followed by a
228 <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt> operator.<p>
231 <dt><tt>dyn_cast<></tt>:
233 <dd>The <tt>dyn_cast<></tt> operator is a "checking cast" operation. It
234 checks to see if the operand is of the specified type, and if so, returns a
235 pointer to it (this operator does not work with references). If the operand is
236 not of the correct type, a null pointer is returned. Thus, this works very much
237 like the <tt>dynamic_cast</tt> operator in C++, and should be used in the same
238 circumstances. An example is:<p>
241 <i>// Loop over all of the phi nodes in a basic block</i>
242 BasicBlock::iterator BBI = BB->begin();
243 for (; <a href="#PhiNode">PHINode</a> *PN = dyn_cast<<a href="#PHINode">PHINode</a>>(&*BBI); ++BBI)
247 Note that you should not use the <tt>dyn_cast<></tt> operator in a series
248 of chained if statements, use an visitor instead... FIXME: continue.<p>
256 <!-- *********************************************************************** -->
257 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
258 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
259 <a name="common">Helpful Hints for Common Operations
260 </b></font></td></tr></table><ul>
261 <!-- *********************************************************************** -->
263 This section describes how to perform some very simple transformations of LLVM
264 code. This is meant to give examples of common idioms used, showing the
265 practical side of LLVM transformations.<p>
267 Because this is a "how-to" section, you should also read about the main classes
268 that you will be working with. The <a href="#coreclasses">Core LLVM Class
269 Hierarchy Reference</a> contains details and descriptions of the main classes
270 that you should know about.<p>
272 <!-- NOTE: this section should be heavy on example code -->
275 <!-- ======================================================================= -->
276 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
277 <tr><td> </td><td width="100%">
278 <font color="#EEEEFF" face="Georgia,Palatino"><b>
279 <a name="inspection">Basic Inspection and Traversal Routines</a>
280 </b></font></td></tr></table><ul>
282 The LLVM compiler infrastructure have many different data structures that may be
283 traversed. Following the example of the C++ standard template library, the
284 techniques used to traverse these various data structures are all basically the
285 same. For a enumerable sequence of values, the <tt>XXXbegin()</tt> function (or
286 method) returns an iterator to the start of the sequence, the <tt>XXXend()</tt>
287 function returns an iterator pointing to one past the last valid element of the
288 sequence, and there is some <tt>XXXiterator</tt> data type that is common
289 between the two operations.<p>
291 Because the pattern for iteration is common across many different aspects of the
292 program representation, the standard template library algorithms may be used on
293 them, and it is easier to remember how to iterate. First we show a few common
294 examples of the data structures that need to be traversed. Other data
295 structures are traversed in very similar ways.<p>
298 <!-- _______________________________________________________________________ -->
299 </ul><h4><a name="iterate_function"><hr size=0>Iterating over the <a
300 href="#BasicBlock"><tt>BasicBlock</tt></a>s in a <a
301 href="#Function"><tt>Function</tt></a> </h4><ul>
303 It's quite common to have a <tt>Function</tt> instance that you'd like
304 to transform in some way; in particular, you'd like to manipulate its
305 <tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over
306 all of the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>.
307 The following is an example that prints the name of a
308 <tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s it
312 // func is a pointer to a Function instance
313 for(Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {
315 // print out the name of the basic block if it has one, and then the
316 // number of instructions that it contains
318 cerr << "Basic block (name=" << i->getName() << ") has "
319 << i->size() << " instructions.\n";
323 Note that i can be used as if it were a pointer for the purposes of
324 invoking member functions of the <tt>Instruction</tt> class. This is
325 because the indirection operator is overloaded for the iterator
326 classes. In the above code, the expression <tt>i->size()</tt> is
327 exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.
329 <!-- _______________________________________________________________________ -->
330 </ul><h4><a name="iterate_basicblock"><hr size=0>Iterating over the <a
331 href="#Instruction"><tt>Instruction</tt></a>s in a <a
332 href="#BasicBlock"><tt>BasicBlock</tt></a> </h4><ul>
334 Just like when dealing with <tt>BasicBlock</tt>s in
335 <tt>Function</tt>s, it's easy to iterate over the individual
336 instructions that make up <tt>BasicBlock</tt>s. Here's a code snippet
337 that prints out each instruction in a <tt>BasicBlock</tt>:
340 // blk is a pointer to a BasicBlock instance
341 for(BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)
342 // the next statement works since operator<<(ostream&,...)
343 // is overloaded for Instruction&
344 cerr << *i << "\n";
347 However, this isn't really the best way to print out the contents of a
348 <tt>BasicBlock</tt>! Since the ostream operators are overloaded for
349 virtually anything you'll care about, you could have just invoked the
350 print routine on the basic block itself: <tt>cerr << *blk <<
353 Note that currently operator<< is implemented for <tt>Value*</tt>, so it
354 will print out the contents of the pointer, instead of
355 the pointer value you might expect. This is a deprecated interface that will
356 be removed in the future, so it's best not to depend on it. To print out the
357 pointer value for now, you must cast to <tt>void*</tt>.<p>
360 <!-- _______________________________________________________________________ -->
361 </ul><h4><a name="iterate_institer"><hr size=0>Iterating over the <a
362 href="#Instruction"><tt>Instruction</tt></a>s in a <a
363 href="#Function"><tt>Function</tt></a></h4><ul>
365 If you're finding that you commonly iterate over a <tt>Function</tt>'s
366 <tt>BasicBlock</tt>s and then that <tt>BasicBlock</tt>'s
367 <tt>Instruction</tt>s, <tt>InstIterator</tt> should be used instead.
368 You'll need to include <a href="/doxygen/InstIterator_8h-source.html"><tt>llvm/Support/InstIterator.h</tt></a>, and then
369 instantiate <tt>InstIterator</tt>s explicitly in your code. Here's a
370 small example that shows how to dump all instructions in a function to
371 stderr (<b>Note:</b> Dereferencing an <tt>InstIterator</tt> yields an
372 <tt>Instruction*</tt>, <i>not</i> an <tt>Instruction&</tt>!):
375 #include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"
377 // Suppose F is a ptr to a function
378 for(inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
379 cerr << **i << "\n";
382 Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
383 worklist with its initial contents. For example, if you wanted to
384 initialize a worklist to contain all instructions in a
385 <tt>Function</tt> F, all you would need to do is something like:
388 std::set<Instruction*> worklist;
389 worklist.insert(inst_begin(F), inst_end(F));
392 The STL set <tt>worklist</tt> would now contain all instructions in
393 the <tt>Function</tt> pointed to by F.
395 <!-- _______________________________________________________________________ -->
396 </ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
397 pointer (and vice-versa) </h4><ul>
399 Sometimes, it'll be useful to grab a reference (or pointer) to a class
400 instance when all you've got at hand is an iterator. Well, extracting
401 a reference or a pointer from an iterator is very straightforward.
402 Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
403 <tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
406 Instruction& inst = *i; // grab reference to instruction reference
407 Instruction* pinst = &*i; // grab pointer to instruction reference
408 const Instruction& inst = *j;
410 However, the iterators you'll be working with in the LLVM framework
411 are special: they will automatically convert to a ptr-to-instance type
412 whenever they need to. Instead of dereferencing the iterator and then
413 taking the address of the result, you can simply assign the iterator
414 to the proper pointer type and you get the dereference and address-of
415 operation as a result of the assignment (behind the scenes, this is a
416 result of overloading casting mechanisms). Thus the last line of the
419 <pre>Instruction* pinst = &*i;</pre>
421 is semantically equivalent to
423 <pre>Instruction* pinst = i;</pre>
425 <b>Caveat emptor</b>: The above syntax works <i>only</i> when you're <i>not</i>
426 working with <tt>dyn_cast</tt>. The template definition of <tt><a
427 href="#isa">dyn_cast</a></tt> isn't implemented to handle this yet, so you'll
428 still need the following in order for things to work properly:
431 BasicBlock::iterator bbi = ...;
432 <a href="#BranchInst">BranchInst</a>* b = <a href="#isa">dyn_cast</a><<a href="#BranchInst">BranchInst</a>>(&*bbi);
435 It's also possible to turn a class pointer into the corresponding
436 iterator. Usually, this conversion is quite inexpensive. The
437 following code snippet illustrates use of the conversion constructors
438 provided by LLVM iterators. By using these, you can explicitly grab
439 the iterator of something without actually obtaining it via iteration
443 void printNextInstruction(Instruction* inst) {
444 BasicBlock::iterator it(inst);
445 ++it; // after this line, it refers to the instruction after *inst.
446 if(it != inst->getParent()->end()) cerr << *it << "\n";
449 Of course, this example is strictly pedagogical, because it'd be much
450 better to explicitly grab the next instruction directly from inst.
453 <!--_______________________________________________________________________-->
454 </ul><h4><a name="iterate_complex"><hr size=0>Finding call sites: a slightly
455 more complex example </h4><ul>
457 Say that you're writing a FunctionPass and would like to count all the
458 locations in the entire module (that is, across every
459 <tt>Function</tt>) where a certain function (i.e. some
460 <tt>Function</tt>*) already in scope. As you'll learn later, you may
461 want to use an <tt>InstVisitor</tt> to accomplish this in a much more
462 straightforward manner, but this example will allow us to explore how
463 you'd do it if you didn't have <tt>InstVisitor</tt> around. In
464 pseudocode, this is what we want to do:
467 initialize callCounter to zero
468 for each Function f in the Module
469 for each BasicBlock b in f
470 for each Instruction i in b
471 if(i is a CallInst and calls the given function)
472 increment callCounter
475 And the actual code is (remember, since we're writing a
476 <tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply
477 has to override the <tt>runOnFunction</tt> method...):
480 Function* targetFunc = ...;
482 class OurFunctionPass : public FunctionPass {
484 OurFunctionPass(): callCounter(0) { }
486 virtual runOnFunction(Function& F) {
487 for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
488 for(BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {
489 if (<a href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a href="#CallInst">CallInst</a>>(&*inst)) {
490 // we know we've encountered a call instruction, so we
491 // need to determine if it's a call to the
492 // function pointed to by m_func or not.
494 if(callInst->getCalledFunction() == targetFunc)
501 unsigned callCounter;
505 <!--_______________________________________________________________________-->
506 </ul><h4><a name="iterate_chains"><hr size=0>Iterating over def-use &
507 use-def chains</h4><ul>
510 def-use chains ("finding all users of"): Value::use_begin/use_end
511 use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
514 <!-- ======================================================================= -->
515 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
516 <tr><td> </td><td width="100%">
517 <font color="#EEEEFF" face="Georgia,Palatino"><b>
518 <a name="simplechanges">Making simple changes</a>
519 </b></font></td></tr></table><ul>
521 <!-- Value::replaceAllUsesWith
522 User::replaceUsesOfWith
523 Point out: include/llvm/Transforms/Utils/
524 especially BasicBlockUtils.h with:
525 ReplaceInstWithValue, ReplaceInstWithInst
530 <!-- *********************************************************************** -->
531 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
532 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
533 <a name="coreclasses">The Core LLVM Class Hierarchy Reference
534 </b></font></td></tr></table><ul>
535 <!-- *********************************************************************** -->
537 The Core LLVM classes are the primary means of representing the program being
538 inspected or transformed. The core LLVM classes are defined in header files in
539 the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
543 <!-- ======================================================================= -->
544 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
545 <tr><td> </td><td width="100%">
546 <font color="#EEEEFF" face="Georgia,Palatino"><b>
547 <a name="Value">The <tt>Value</tt> class</a>
548 </b></font></td></tr></table><ul>
550 <tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
551 doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
554 The <tt>Value</tt> class is the most important class in LLVM Source base. It
555 represents a typed value that may be used (among other things) as an operand to
556 an instruction. There are many different types of <tt>Value</tt>s, such as <a
557 href="#Constant"><tt>Constant</tt></a>s, <a
558 href="#Argument"><tt>Argument</tt></a>s, and even <a
559 href="#Instruction"><tt>Instruction</tt></a>s and <a
560 href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
562 A particular <tt>Value</tt> may be used many times in the LLVM representation
563 for a program. For example, an incoming argument to a function (represented
564 with an instance of the <a href="#Argument">Argument</a> class) is "used" by
565 every instruction in the function that references the argument. To keep track
566 of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
567 href="#User"><tt>User</tt></a>s that is using it (the <a
568 href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
569 graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
570 def-use information in the program, and is accessible through the <tt>use_</tt>*
571 methods, shown below.<p>
573 Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
574 this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
575 method. <a name="#nameWarning">In addition, all LLVM values can be named. The
576 "name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
579 %<b>foo</b> = add int 1, 2
582 The name of this instruction is "foo". <b>NOTE</b> that the name of any value
583 may be missing (an empty string), so names should <b>ONLY</b> be used for
584 debugging (making the source code easier to read, debugging printouts), they
585 should not be used to keep track of values or map between them. For this
586 purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
589 One important aspect of LLVM is that there is no distinction between an SSA
590 variable and the operation that produces it. Because of this, any reference to
591 the value produced by an instruction (or the value available as an incoming
592 argument, for example) is represented as a direct pointer to the class that
593 represents this value. Although this may take some getting used to, it
594 simplifies the representation and makes it easier to manipulate.<p>
597 <!-- _______________________________________________________________________ -->
598 </ul><h4><a name="m_Value"><hr size=0>Important Public Members of
599 the <tt>Value</tt> class</h4><ul>
601 <li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
602 <tt>Value::use_const_iterator</tt>
603 - Typedef for const_iterator over the use-list<br>
604 <tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
605 <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
606 <tt>use_iterator use_begin()</tt>
607 - Get an iterator to the start of the use-list.<br>
608 <tt>use_iterator use_end()</tt>
609 - Get an iterator to the end of the use-list.<br>
610 <tt><a href="#User">User</a> *use_back()</tt>
611 - Returns the last element in the list.<p>
613 These methods are the interface to access the def-use information in LLVM. As with all other iterators in LLVM, the naming conventions follow the conventions defined by the <a href="#stl">STL</a>.<p>
615 <li><tt><a href="#Type">Type</a> *getType() const</tt><p>
616 This method returns the Type of the Value.
618 <li><tt>bool hasName() const</tt><br>
619 <tt>std::string getName() const</tt><br>
620 <tt>void setName(const std::string &Name)</tt><p>
622 This family of methods is used to access and assign a name to a <tt>Value</tt>,
623 be aware of the <a href="#nameWarning">precaution above</a>.<p>
626 <li><tt>void replaceAllUsesWith(Value *V)</tt><p>
628 This method traverses the use list of a <tt>Value</tt> changing all <a
629 href="#User"><tt>User</tt>'s</a> of the current value to refer to "<tt>V</tt>"
630 instead. For example, if you detect that an instruction always produces a
631 constant value (for example through constant folding), you can replace all uses
632 of the instruction with the constant like this:<p>
635 Inst->replaceAllUsesWith(ConstVal);
640 <!-- ======================================================================= -->
641 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
642 <tr><td> </td><td width="100%">
643 <font color="#EEEEFF" face="Georgia,Palatino"><b>
644 <a name="User">The <tt>User</tt> class</a>
645 </b></font></td></tr></table><ul>
647 <tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
648 doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
649 Superclass: <a href="#Value"><tt>Value</tt></a><p>
652 The <tt>User</tt> class is the common base class of all LLVM nodes that may
653 refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
654 that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
655 referring to. The <tt>User</tt> class itself is a subclass of
658 The operands of a <tt>User</tt> point directly to the LLVM <a
659 href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
660 Single Assignment (SSA) form, there can only be one definition referred to,
661 allowing this direct connection. This connection provides the use-def
662 information in LLVM.<p>
664 <!-- _______________________________________________________________________ -->
665 </ul><h4><a name="m_User"><hr size=0>Important Public Members of
666 the <tt>User</tt> class</h4><ul>
668 The <tt>User</tt> class exposes the operand list in two ways: through an index
669 access interface and through an iterator based interface.<p>
671 <li><tt>Value *getOperand(unsigned i)</tt><br>
672 <tt>unsigned getNumOperands()</tt><p>
674 These two methods expose the operands of the <tt>User</tt> in a convenient form
675 for direct access.<p>
677 <li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
678 <tt>User::op_const_iterator</tt>
679 <tt>use_iterator op_begin()</tt>
680 - Get an iterator to the start of the operand list.<br>
681 <tt>use_iterator op_end()</tt>
682 - Get an iterator to the end of the operand list.<p>
684 Together, these methods make up the iterator based interface to the operands of
689 <!-- ======================================================================= -->
690 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
691 <tr><td> </td><td width="100%">
692 <font color="#EEEEFF" face="Georgia,Palatino"><b>
693 <a name="Instruction">The <tt>Instruction</tt> class</a>
694 </b></font></td></tr></table><ul>
697 href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
698 doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
699 Superclasses: <a href="#User"><tt>User</tt></a>, <a
700 href="#Value"><tt>Value</tt></a><p>
702 The <tt>Instruction</tt> class is the common base class for all LLVM
703 instructions. It provides only a few methods, but is a very commonly used
704 class. The primary data tracked by the <tt>Instruction</tt> class itself is the
705 opcode (instruction type) and the parent <a
706 href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
707 into. To represent a specific type of instruction, one of many subclasses of
708 <tt>Instruction</tt> are used.<p>
710 Because the <tt>Instruction</tt> class subclasses the <a
711 href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
712 way as for other <a href="#User"><tt>User</tt></a>s (with the
713 <tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
714 <tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
717 <!-- _______________________________________________________________________ -->
718 </ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
719 the <tt>Instruction</tt> class</h4><ul>
721 <li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
723 Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
724 <tt>Instruction</tt> is embedded into.<p>
726 <li><tt>bool hasSideEffects()</tt><p>
728 Returns true if the instruction has side effects, i.e. it is a <tt>call</tt>,
729 <tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
731 <li><tt>unsigned getOpcode()</tt><p>
733 Returns the opcode for the <tt>Instruction</tt>.<p>
737 \subsection{Subclasses of Instruction :}
739 <li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
741 <li><tt>bool swapOperands()</tt>: Exchange the two operands to this instruction. If the instruction cannot be reversed (i.e. if it's a Div), it returns true.
743 <li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
745 <li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
746 <li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
747 <li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
750 <li>PHINode : This represents the PHI instructions in the SSA form.
752 <li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
753 <li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
754 <li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
755 <li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
756 <li><tt> void addIncoming(Value *D, BasicBlock *BB)</tt>:
757 Add an incoming value to the end of the PHI list
758 <li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
759 Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
761 <li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
762 <li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
764 <li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
766 <li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
768 <li><tt>Value * getPointerOperand ()</tt>: Returns the Pointer Operand which is typically the 0th operand.
770 <li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
772 <li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
773 <li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
774 <li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
782 <!-- ======================================================================= -->
783 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
784 <tr><td> </td><td width="100%">
785 <font color="#EEEEFF" face="Georgia,Palatino"><b>
786 <a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
787 </b></font></td></tr></table><ul>
790 href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
791 doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
792 Superclass: <a href="#Value"><tt>Value</tt></a><p>
795 This class represents a single entry multiple exit section of the code, commonly
796 known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
797 maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
798 the body of the block. Matching the language definition, the last element of
799 this list of instructions is always a terminator instruction (a subclass of the
800 <a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
802 In addition to tracking the list of instructions that make up the block, the
803 <tt>BasicBlock</tt> class also keeps track of the <a
804 href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
806 Note that <tt>BasicBlock</tt>s themselves are <a
807 href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
808 like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
812 <!-- _______________________________________________________________________ -->
813 </ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
814 the <tt>BasicBlock</tt> class</h4><ul>
816 <li><tt>BasicBlock(const std::string &Name = "", <a
817 href="#Function">Function</a> *Parent = 0)</tt><p>
819 The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
820 insertion into a function. The constructor simply takes a name for the new
821 block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
822 into. If the <tt>Parent</tt> parameter is specified, the new
823 <tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
824 href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
825 manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
827 <li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
828 <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
829 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
830 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
832 These methods and typedefs are forwarding functions that have the same semantics
833 as the standard library methods of the same names. These methods expose the
834 underlying instruction list of a basic block in a way that is easy to
835 manipulate. To get the full complement of container operations (including
836 operations to update the list), you must use the <tt>getInstList()</tt>
839 <li><tt>BasicBlock::InstListType &getInstList()</tt><p>
841 This method is used to get access to the underlying container that actually
842 holds the Instructions. This method must be used when there isn't a forwarding
843 function in the <tt>BasicBlock</tt> class for the operation that you would like
844 to perform. Because there are no forwarding functions for "updating"
845 operations, you need to use this if you want to update the contents of a
846 <tt>BasicBlock</tt>.<p>
848 <li><tt><A href="#Function">Function</a> *getParent()</tt><p>
850 Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
851 embedded into, or a null pointer if it is homeless.<p>
853 <li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
855 Returns a pointer to the terminator instruction that appears at the end of the
856 <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
857 instruction in the block is not a terminator, then a null pointer is
861 <!-- ======================================================================= -->
862 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
863 <tr><td> </td><td width="100%">
864 <font color="#EEEEFF" face="Georgia,Palatino"><b>
865 <a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
866 </b></font></td></tr></table><ul>
869 href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
870 doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
871 Superclasses: <a href="#User"><tt>User</tt></a>, <a
872 href="#Value"><tt>Value</tt></a><p>
874 Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
875 href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
876 visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
877 Because they are visible at global scope, they are also subject to linking with
878 other globals defined in different translation units. To control the linking
879 process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
880 <tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
882 If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
883 <tt>static</tt> in C), it is not visible to code outside the current translation
884 unit, and does not participate in linking. If it has external linkage, it is
885 visible to external code, and does participate in linking. In addition to
886 linkage information, <tt>GlobalValue</tt>s keep track of which <a
887 href="#Module"><tt>Module</tt></a> they are currently part of.<p>
889 Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
890 their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
891 always a pointer to its contents. This is explained in the LLVM Language
895 <!-- _______________________________________________________________________ -->
896 </ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
897 the <tt>GlobalValue</tt> class</h4><ul>
899 <li><tt>bool hasInternalLinkage() const</tt><br>
900 <tt>bool hasExternalLinkage() const</tt><br>
901 <tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
903 These methods manipulate the linkage characteristics of the
904 <tt>GlobalValue</tt>.<p>
906 <li><tt><a href="#Module">Module</a> *getParent()</tt><p>
908 This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
909 currently embedded into.<p>
913 <!-- ======================================================================= -->
914 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
915 <tr><td> </td><td width="100%">
916 <font color="#EEEEFF" face="Georgia,Palatino"><b>
917 <a name="Function">The <tt>Function</tt> class</a>
918 </b></font></td></tr></table><ul>
921 href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
922 doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
923 Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
924 href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
926 The <tt>Function</tt> class represents a single procedure in LLVM. It is
927 actually one of the more complex classes in the LLVM heirarchy because it must
928 keep track of a large amount of data. The <tt>Function</tt> class keeps track
929 of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
930 href="#Argument"><tt>Argument</tt></a>s, and a <a
931 href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
933 The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
934 used part of <tt>Function</tt> objects. The list imposes an implicit ordering
935 of the blocks in the function, which indicate how the code will be layed out by
936 the backend. Additionally, the first <a
937 href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
938 <tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
939 block. There are no implicit exit nodes, and in fact there may be multiple exit
940 nodes from a single <tt>Function</tt>. If the <a
941 href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
942 the <tt>Function</tt> is actually a function declaration: the actual body of the
943 function hasn't been linked in yet.<p>
945 In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
946 <tt>Function</tt> class also keeps track of the list of formal <a
947 href="#Argument"><tt>Argument</tt></a>s that the function receives. This
948 container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
949 nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
950 the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
952 The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
953 feature that is only used when you have to look up a value by name. Aside from
954 that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
955 make sure that there are not conflicts between the names of <a
956 href="#Instruction"><tt>Instruction</tt></a>s, <a
957 href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
958 href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
961 <!-- _______________________________________________________________________ -->
962 </ul><h4><a name="m_Function"><hr size=0>Important Public Members of
963 the <tt>Function</tt> class</h4><ul>
965 <li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &N = "")</tt><p>
967 Constructor used when you need to create new <tt>Function</tt>s to add the the
968 program. The constructor must specify the type of the function to create and
969 whether or not it should start out with internal or external linkage.<p>
971 <li><tt>bool isExternal()</tt><p>
973 Return whether or not the <tt>Function</tt> has a body defined. If the function
974 is "external", it does not have a body, and thus must be resolved by linking
975 with a function defined in a different translation unit.<p>
978 <li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
979 <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
980 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
981 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
983 These are forwarding methods that make it easy to access the contents of a
984 <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
987 <li><tt>Function::BasicBlockListType &getBasicBlockList()</tt><p>
989 Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
990 neccesary to use when you need to update the list or perform a complex action
991 that doesn't have a forwarding method.<p>
994 <li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
995 <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
996 <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
997 <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
999 These are forwarding methods that make it easy to access the contents of a
1000 <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
1002 <li><tt>Function::ArgumentListType &getArgumentList()</tt><p>
1004 Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
1005 neccesary to use when you need to update the list or perform a complex action
1006 that doesn't have a forwarding method.<p>
1010 <li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
1012 Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
1013 function. Because the entry block for the function is always the first block,
1014 this returns the first block of the <tt>Function</tt>.<p>
1016 <li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
1017 <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
1019 This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
1020 and returns the return type of the function, or the <a
1021 href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
1024 <li><tt>bool hasSymbolTable() const</tt><p>
1026 Return true if the <tt>Function</tt> has a symbol table allocated to it and if
1027 there is at least one entry in it.<p>
1029 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1031 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1032 <tt>Function</tt> or a null pointer if one has not been allocated (because there
1033 are no named values in the function).<p>
1035 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
1037 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1038 <tt>Function</tt> or allocate a new <a
1039 href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
1040 should only be used when adding elements to the <a
1041 href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
1042 not left laying around.<p>
1046 <!-- ======================================================================= -->
1047 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1048 <tr><td> </td><td width="100%">
1049 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1050 <a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
1051 </b></font></td></tr></table><ul>
1054 href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
1055 doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
1056 Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
1057 href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
1059 Global variables are represented with the (suprise suprise)
1060 <tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
1061 also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
1062 are always referenced by their address (global values must live in memory, so
1063 their "name" refers to their address). Global variables may have an initial
1064 value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
1065 have an initializer, they may be marked as "constant" themselves (indicating
1066 that their contents never change at runtime).<p>
1069 <!-- _______________________________________________________________________ -->
1070 </ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
1071 <tt>GlobalVariable</tt> class</h4><ul>
1073 <li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
1074 isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
1075 &Name = "")</tt><p>
1077 Create a new global variable of the specified type. If <tt>isConstant</tt> is
1078 true then the global variable will be marked as unchanging for the program, and
1079 if <tt>isInternal</tt> is true the resultant global variable will have internal
1080 linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
1083 <li><tt>bool isConstant() const</tt><p>
1085 Returns true if this is a global variable is known not to be modified at
1089 <li><tt>bool hasInitializer()</tt><p>
1091 Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
1094 <li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
1096 Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
1097 this method if there is no initializer.<p>
1100 <!-- ======================================================================= -->
1101 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1102 <tr><td> </td><td width="100%">
1103 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1104 <a name="Module">The <tt>Module</tt> class</a>
1105 </b></font></td></tr></table><ul>
1108 href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
1109 doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
1111 The <tt>Module</tt> class represents the top level structure present in LLVM
1112 programs. An LLVM module is effectively either a translation unit of the
1113 original program or a combination of several translation units merged by the
1114 linker. The <tt>Module</tt> class keeps track of a list of <a
1115 href="#Function"><tt>Function</tt></a>s, a list of <a
1116 href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
1117 href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
1118 helpful member functions that try to make common operations easy.<p>
1121 <!-- _______________________________________________________________________ -->
1122 </ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
1123 <tt>Module</tt> class</h4><ul>
1125 <li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
1126 <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
1127 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1128 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1130 These are forwarding methods that make it easy to access the contents of a
1131 <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
1134 <li><tt>Module::FunctionListType &getFunctionList()</tt><p>
1136 Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
1137 neccesary to use when you need to update the list or perform a complex action
1138 that doesn't have a forwarding method.<p>
1140 <!-- Global Variable -->
1143 <li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
1144 <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
1145 <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
1146 <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
1148 These are forwarding methods that make it easy to access the contents of a
1149 <tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
1152 <li><tt>Module::GlobalListType &getGlobalList()</tt><p>
1154 Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
1155 This is neccesary to use when you need to update the list or perform a complex
1156 action that doesn't have a forwarding method.<p>
1159 <!-- Symbol table stuff -->
1162 <li><tt>bool hasSymbolTable() const</tt><p>
1164 Return true if the <tt>Module</tt> has a symbol table allocated to it and if
1165 there is at least one entry in it.<p>
1167 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1169 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1170 <tt>Module</tt> or a null pointer if one has not been allocated (because there
1171 are no named values in the function).<p>
1173 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
1175 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1176 <tt>Module</tt> or allocate a new <a
1177 href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
1178 should only be used when adding elements to the <a
1179 href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
1180 not left laying around.<p>
1183 <!-- Convenience methods -->
1186 <li><tt><a href="#Function">Function</a> *getFunction(const std::string &Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt><p>
1188 Look up the specified function in the <tt>Module</tt> <a
1189 href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
1193 <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
1194 &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
1196 Look up the specified function in the <tt>Module</tt> <a
1197 href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
1198 external declaration for the function and return it.<p>
1201 <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
1203 If there is at least one entry in the <a
1204 href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
1205 href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
1209 <li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
1212 Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
1213 <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
1214 is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
1218 <!-- ======================================================================= -->
1219 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1220 <tr><td> </td><td width="100%">
1221 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1222 <a name="Constant">The <tt>Constant</tt> class and subclasses</a>
1223 </b></font></td></tr></table><ul>
1225 Constant represents a base class for different types of constants. It is
1226 subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
1227 ConstantArray etc for representing the various types of Constants.<p>
1230 <!-- _______________________________________________________________________ -->
1231 </ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1233 <li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
1238 \subsection{Important Subclasses of Constant}
1240 <li>ConstantSInt : This subclass of Constant represents a signed integer constant.
1242 <li><tt>int64_t getValue () const</tt>: Returns the underlying value of this constant.
1244 <li>ConstantUInt : This class represents an unsigned integer.
1246 <li><tt>uint64_t getValue () const</tt>: Returns the underlying value of this constant.
1248 <li>ConstantFP : This class represents a floating point constant.
1250 <li><tt>double getValue () const</tt>: Returns the underlying value of this constant.
1252 <li>ConstantBool : This represents a boolean constant.
1254 <li><tt>bool getValue () const</tt>: Returns the underlying value of this constant.
1256 <li>ConstantArray : This represents a constant array.
1258 <li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1260 <li>ConstantStruct : This represents a constant struct.
1262 <li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1264 <li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
1266 <li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
1271 <!-- ======================================================================= -->
1272 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1273 <tr><td> </td><td width="100%">
1274 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1275 <a name="Type">The <tt>Type</tt> class and Derived Types</a>
1276 </b></font></td></tr></table><ul>
1278 Type as noted earlier is also a subclass of a Value class. Any primitive
1279 type (like int, short etc) in LLVM is an instance of Type Class. All
1280 other types are instances of subclasses of type like FunctionType,
1281 ArrayType etc. DerivedType is the interface for all such dervied types
1282 including FunctionType, ArrayType, PointerType, StructType. Types can have
1283 names. They can be recursive (StructType). There exists exactly one instance
1284 of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
1286 <!-- _______________________________________________________________________ -->
1287 </ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1289 <li><tt>PrimitiveID getPrimitiveID () const</tt>: Returns the base type of the type.
1290 <li><tt> bool isSigned () const</tt>: Returns whether an integral numeric type is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is not true for Float and Double.
1291 <li><tt>bool isUnsigned () const</tt>: Returns whether a numeric type is unsigned. This is not quite the complement of isSigned... nonnumeric types return false as they do with isSigned. This returns true for UByteTy, UShortTy, UIntTy, and ULongTy.
1292 <li><tt> bool isInteger () const</tt>: Equilivent to isSigned() || isUnsigned(), but with only a single virtual function invocation.
1293 <li><tt>bool isIntegral () const</tt>: Returns true if this is an integral type, which is either Bool type or one of the Integer types.
1295 <li><tt>bool isFloatingPoint ()</tt>: Return true if this is one of the two floating point types.
1296 <li><tt>bool isRecursive () const</tt>: Returns rue if the type graph contains a cycle.
1297 <li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if this type can be converted to 'Ty' without any reinterpretation of bits. For example, uint to int.
1298 <li><tt>bool isPrimitiveType () const</tt>: Returns true if it is a primitive type.
1299 <li><tt>bool isDerivedType () const</tt>: Returns true if it is a derived type.
1300 <li><tt>const Type * getContainedType (unsigned i) const</tt>:
1301 This method is used to implement the type iterator. For derived types, this returns the types 'contained' in the derived type, returning 0 when 'i' becomes invalid. This allows the user to iterate over the types in a struct, for example, really easily.
1302 <li><tt>unsigned getNumContainedTypes () const</tt>: Return the number of types in the derived type.
1306 \subsection{Derived Types}
1308 <li>SequentialType : This is subclassed by ArrayType and PointerType
1310 <li><tt>const Type * getElementType () const</tt>: Returns the type of each of the elements in the sequential type.
1312 <li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
1314 <li><tt>unsigned getNumElements () const</tt>: Returns the number of elements in the array.
1316 <li>PointerType : Subclass of SequentialType for pointer types.
1317 <li>StructType : subclass of DerivedTypes for struct types
1318 <li>FunctionType : subclass of DerivedTypes for function types.
1321 <li><tt>bool isVarArg () const</tt>: Returns true if its a vararg function
1322 <li><tt> const Type * getReturnType () const</tt>: Returns the return type of the function.
1323 <li><tt> const ParamTypes &getParamTypes () const</tt>: Returns a vector of parameter types.
1324 <li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
1325 <li><tt> const unsigned getNumParams () const</tt>: Returns the number of formal parameters.
1332 <!-- ======================================================================= -->
1333 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1334 <tr><td> </td><td width="100%">
1335 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1336 <a name="Argument">The <tt>Argument</tt> class</a>
1337 </b></font></td></tr></table><ul>
1339 This subclass of Value defines the interface for incoming formal arguments to a
1340 function. A Function maitanis a list of its formal arguments. An argument has a
1341 pointer to the parent Function.
1346 <!-- *********************************************************************** -->
1348 <!-- *********************************************************************** -->
1351 <address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
1352 <a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1353 <!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
1354 <!-- hhmts start -->
1355 Last modified: Mon Sep 9 19:38:23 CDT 2002
1357 </font></body></html>