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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>
195 <!-- *********************************************************************** -->
196 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
197 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
198 <a name="common">Helpful Hints for Common Operations
199 </b></font></td></tr></table><ul>
200 <!-- *********************************************************************** -->
202 This section describes how to perform some very simple transformations of LLVM
203 code. This is meant to give examples of common idioms used, showing the
204 practical side of LLVM transformations.<p>
206 Because this is a "how-to" section, you should also read about the main classes
207 that you will be working with. The <a href="#coreclasses">Core LLVM Class
208 Hierarchy Reference</a> contains details and descriptions of the main classes
209 that you should know about.<p>
211 <!-- NOTE: this section should be heavy on example code -->
214 <!-- ======================================================================= -->
215 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
216 <tr><td> </td><td width="100%">
217 <font color="#EEEEFF" face="Georgia,Palatino"><b>
218 <a name="inspection">Basic Inspection and Traversal Routines</a>
219 </b></font></td></tr></table><ul>
222 <!-- LLVM has heirarchical representation: Module, Function, BasicBlock,
223 Instruction. Common patterns for all levels. -->
225 <!-- _______________________________________________________________________ -->
226 </ul><h4><a name="iterate_function"><hr size=0>Iterating over the
227 <tt>BasicBlock</tt>s in a <tt>Function</tt> </h4><ul>
229 It's quite common to have a <tt>Function</tt> instance that you'd like
230 to transform in some way; in particular, you'd like to manipulate its
231 <tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over
232 all of the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>.
233 The following is an example that prints the name of a
234 <tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s it
238 // func is a pointer to a Function instance
239 for(Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {
241 // print out the name of the basic block if it has one, and then the
242 // number of instructions that it contains
244 cerr << "Basic block (name=" << i->getName() << ") has "
245 << i->size() << " instructions.\n";
249 Note that i can be used as if it were a pointer for the purposes of
250 invoking member functions of the <tt>Instruction</tt> class. This is
251 because the indirection operator is overloaded for the iterator
252 classes. In the above code, the expression <tt>i->size()</tt> is
253 exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.
255 <!-- _______________________________________________________________________ -->
256 </ul><h4><a name="iterate_basicblock"><hr size=0>Iterating over the
257 <tt>Instruction</tt>s in a <tt>BasicBlock</tt> </h4><ul>
259 Just like when dealing with <tt>BasicBlock</tt>s in
260 <tt>Function</tt>s, it's easy to iterate over the individual
261 instructions that make up <tt>BasicBlock</tt>s. Here's a code snippet
262 that prints out each instruction in a <tt>BasicBlock</tt>:
265 // blk is a pointer to a BasicBlock instance
266 for(BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i) {
267 // the next statement works since operator<<(ostream&,...)
268 // is overloaded for Instruction&
269 cerr << *i << endl;
272 However, this isn't really the best way to print out the contents of a
273 <tt>BasicBlock</tt>! Since the ostream operators are overloaded for
274 virtually anything you'll care about, you could have just invoked the
275 print routine on the basic block itself: <tt>cerr << *blk <<
278 Note that currently operator<< is implemented for <tt>Value*</tt>, so it
279 will print out the contents of the pointer, instead of
280 the pointer value you might expect. This is a deprecated interface that will
281 be removed in the future, so it's best not to depend on it. To print out the
282 pointer value for now, you must cast to <tt>void*</tt>.<p>
284 <!-- _______________________________________________________________________ -->
285 </ul><h4><a name="iterate_institer"><hr size=0>Iterating over the
286 <tt>Instruction</tt>s in a <tt>Function</tt></h4><ul>
288 <!-- Using llvm/Support/InstIterator.h to directly get at the instructions in a
291 Warning: *I returns an Instruction*, not an Instruction&
297 <!-- _______________________________________________________________________ -->
298 </ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
301 Sometimes, it'll be useful to grab a reference (or pointer) to a class
302 instance when all you've got at hand is an iterator. Well, extracting
303 a reference or a pointer from an iterator is very straightforward.
304 Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
305 <tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
308 Instruction& inst = *i; // grab reference to instruction reference
309 Instruction* pinst = &*i; // grab pointer to instruction reference
310 const Instruction& inst = *j;
312 However, the iterators you'll be working with in the LLVM framework
313 are special: they will automatically convert to a ptr-to-instance type
314 whenever they need to. Instead of dereferencing the iterator and then
315 taking the address of the result, you can simply assign the iterator
316 to the proper pointer type and you get the dereference and address-of
317 operation as a result of the assignment (behind the scenes, this is a
318 result of overloading casting mechanisms). Thus the last line of the
321 <pre>Instruction* pinst = &*i;</pre>
323 is semantically equivalent to
325 <pre>Instruction* pinst = i;</pre>
327 <b>Caveat emptor</b>: The above syntax works <i>only</i> when you're
328 <i>not</i> working with <tt>dyn_cast</tt>. The template definition of
329 <tt>dyn_cast</tt> isn't implemented to handle this yet, so you'll
330 still need the following in order for things to work properly:
333 BasicBlock::iterator bbi = ...;
334 BranchInst* b = dyn_cast<BranchInst>(&*bbi);
337 The following code snippet illustrates use of the conversion
338 constructors provided by LLVM iterators. By using these, you can
339 explicitly grab the iterator of something without actually obtaining
340 it via iteration over some structure:
343 void printNextInstruction(Instruction* inst) {
344 BasicBlock::iterator it(inst);
345 ++it; // after this line, it refers to the instruction after *inst.
346 if(it != inst->getParent()->end()) cerr << *it << endl;
349 Of course, this example is strictly pedagogical, because it'd be much
350 better to explicitly grab the next instruction directly from inst.
352 <!-- dereferenced iterator = Class &
353 iterators have converting constructor for 'Class *'
354 iterators automatically convert to 'Class *' except in dyn_cast<> case
357 <!--_______________________________________________________________________-->
358 </ul><h4><a name="iterate_complex"><hr size=0>Finding call sites: a slightly
359 more complex example </h4><ul>
361 Say that you're writing a FunctionPass and would like to count all the
362 locations in the entire module (that is, across every <tt>Function</tt>)
363 where a certain function named foo (that takes an int and returns an
364 int) is called. As you'll learn later, you may want to use an
365 <tt>InstVisitor</tt> to accomplish this in a much more straightforward
366 manner, but this example will allow us to explore how you'd do it if
367 you didn't have <tt>InstVisitor</tt> around. In pseudocode, this is
371 initialize callCounter to zero
372 for each Function f in the Module
373 for each BasicBlock b in f
374 for each Instruction i in b
375 if(i is a CallInst and foo is the function it calls)
376 increment callCounter
379 And the actual code is (remember, since we're writing a
380 <tt>FunctionPass</tt> our <tt>FunctionPass</tt>-derived class simply
381 has to override the <tt>runOnFunction</tt> method...):
385 // Assume callCounter is a private member of the pass class being written,
386 // and has been initialized in the pass class constructor.
388 virtual runOnFunction(Function& F) {
390 // Remember, we assumed that the signature of foo was "int foo(int)";
391 // the first thing we'll do is grab the pointer to that function (as a
392 // Function*) so we can use it later when we're examining the
393 // parameters of a CallInst. All of the code before the call to
394 // Module::getOrInsertFunction() is in preparation to do symbol-table
395 // to find the function pointer.
397 vector<const Type*> params;
398 params.push_back(Type::IntTy);
399 const FunctionType* fooType = FunctionType::get(Type::IntTy, params);
400 Function* foo = F.getParent()->getOrInsertFunction("foo", fooType);
402 // Start iterating and (as per the pseudocode), increment callCounter.
404 for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
405 for(BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {
406 if(CallInst* callInst = dyn_cast<CallInst>(&*inst)) {
407 // we know we've encountered a call instruction, so we
408 // need to determine if it's a call to foo or not
410 if(callInst->getCalledFunction() == foo)
418 We could then print out the value of callCounter (if we wanted to)
419 inside the doFinalization method of our FunctionPass.
422 <!--_______________________________________________________________________-->
423 </ul><h4><a name="iterate_chains"><hr size=0>Iterating over def-use &
424 use-def chains</h4><ul>
428 def-use chains ("finding all users of"): Value::use_begin/use_end
429 use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
432 <!-- ======================================================================= -->
433 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
434 <tr><td> </td><td width="100%">
435 <font color="#EEEEFF" face="Georgia,Palatino"><b>
436 <a name="simplechanges">Making simple changes</a>
437 </b></font></td></tr></table><ul>
439 <!-- Value::replaceAllUsesWith
440 User::replaceUsesOfWith
441 Point out: include/llvm/Transforms/Utils/
442 especially BasicBlockUtils.h with:
443 ReplaceInstWithValue, ReplaceInstWithInst
448 <!-- *********************************************************************** -->
449 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
450 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
451 <a name="coreclasses">The Core LLVM Class Hierarchy Reference
452 </b></font></td></tr></table><ul>
453 <!-- *********************************************************************** -->
455 The Core LLVM classes are the primary means of representing the program being
456 inspected or transformed. The core LLVM classes are defined in header files in
457 the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
461 <!-- ======================================================================= -->
462 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
463 <tr><td> </td><td width="100%">
464 <font color="#EEEEFF" face="Georgia,Palatino"><b>
465 <a name="Value">The <tt>Value</tt> class</a>
466 </b></font></td></tr></table><ul>
468 <tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
469 doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
472 The <tt>Value</tt> class is the most important class in LLVM Source base. It
473 represents a typed value that may be used (among other things) as an operand to
474 an instruction. There are many different types of <tt>Value</tt>s, such as <a
475 href="#Constant"><tt>Constant</tt></a>s, <a
476 href="#Argument"><tt>Argument</tt></a>s, and even <a
477 href="#Instruction"><tt>Instruction</tt></a>s and <a
478 href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
480 A particular <tt>Value</tt> may be used many times in the LLVM representation
481 for a program. For example, an incoming argument to a function (represented
482 with an instance of the <a href="#Argument">Argument</a> class) is "used" by
483 every instruction in the function that references the argument. To keep track
484 of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
485 href="#User"><tt>User</tt></a>s that is using it (the <a
486 href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
487 graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
488 def-use information in the program, and is accessible through the <tt>use_</tt>*
489 methods, shown below.<p>
491 Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
492 this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
493 method. <a name="#nameWarning">In addition, all LLVM values can be named. The
494 "name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
497 %<b>foo</b> = add int 1, 2
500 The name of this instruction is "foo". <b>NOTE</b> that the name of any value
501 may be missing (an empty string), so names should <b>ONLY</b> be used for
502 debugging (making the source code easier to read, debugging printouts), they
503 should not be used to keep track of values or map between them. For this
504 purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
507 One important aspect of LLVM is that there is no distinction between an SSA
508 variable and the operation that produces it. Because of this, any reference to
509 the value produced by an instruction (or the value available as an incoming
510 argument, for example) is represented as a direct pointer to the class that
511 represents this value. Although this may take some getting used to, it
512 simplifies the representation and makes it easier to manipulate.<p>
515 <!-- _______________________________________________________________________ -->
516 </ul><h4><a name="m_Value"><hr size=0>Important Public Members of
517 the <tt>Value</tt> class</h4><ul>
519 <li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
520 <tt>Value::use_const_iterator</tt>
521 - Typedef for const_iterator over the use-list<br>
522 <tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
523 <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
524 <tt>use_iterator use_begin()</tt>
525 - Get an iterator to the start of the use-list.<br>
526 <tt>use_iterator use_end()</tt>
527 - Get an iterator to the end of the use-list.<br>
528 <tt><a href="#User">User</a> *use_back()</tt>
529 - Returns the last element in the list.<p>
531 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>
533 <li><tt><a href="#Type">Type</a> *getType() const</tt><p>
534 This method returns the Type of the Value.
536 <li><tt>bool hasName() const</tt><br>
537 <tt>std::string getName() const</tt><br>
538 <tt>void setName(const std::string &Name)</tt><p>
540 This family of methods is used to access and assign a name to a <tt>Value</tt>,
541 be aware of the <a href="#nameWarning">precaution above</a>.<p>
544 <li><tt>void replaceAllUsesWith(Value *V)</tt><p>
546 This method traverses the use list of a <tt>Value</tt> changing all <a
547 href="#User"><tt>User</tt>'s</a> of the current value to refer to "<tt>V</tt>"
548 instead. For example, if you detect that an instruction always produces a
549 constant value (for example through constant folding), you can replace all uses
550 of the instruction with the constant like this:<p>
553 Inst->replaceAllUsesWith(ConstVal);
558 <!-- ======================================================================= -->
559 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
560 <tr><td> </td><td width="100%">
561 <font color="#EEEEFF" face="Georgia,Palatino"><b>
562 <a name="User">The <tt>User</tt> class</a>
563 </b></font></td></tr></table><ul>
565 <tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
566 doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
567 Superclass: <a href="#Value"><tt>Value</tt></a><p>
570 The <tt>User</tt> class is the common base class of all LLVM nodes that may
571 refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
572 that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
573 referring to. The <tt>User</tt> class itself is a subclass of
576 The operands of a <tt>User</tt> point directly to the LLVM <a
577 href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
578 Single Assignment (SSA) form, there can only be one definition referred to,
579 allowing this direct connection. This connection provides the use-def
580 information in LLVM.<p>
582 <!-- _______________________________________________________________________ -->
583 </ul><h4><a name="m_User"><hr size=0>Important Public Members of
584 the <tt>User</tt> class</h4><ul>
586 The <tt>User</tt> class exposes the operand list in two ways: through an index
587 access interface and through an iterator based interface.<p>
589 <li><tt>Value *getOperand(unsigned i)</tt><br>
590 <tt>unsigned getNumOperands()</tt><p>
592 These two methods expose the operands of the <tt>User</tt> in a convenient form
593 for direct access.<p>
595 <li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
596 <tt>User::op_const_iterator</tt>
597 <tt>use_iterator op_begin()</tt>
598 - Get an iterator to the start of the operand list.<br>
599 <tt>use_iterator op_end()</tt>
600 - Get an iterator to the end of the operand list.<p>
602 Together, these methods make up the iterator based interface to the operands of
607 <!-- ======================================================================= -->
608 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
609 <tr><td> </td><td width="100%">
610 <font color="#EEEEFF" face="Georgia,Palatino"><b>
611 <a name="Instruction">The <tt>Instruction</tt> class</a>
612 </b></font></td></tr></table><ul>
615 href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
616 doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
617 Superclasses: <a href="#User"><tt>User</tt></a>, <a
618 href="#Value"><tt>Value</tt></a><p>
620 The <tt>Instruction</tt> class is the common base class for all LLVM
621 instructions. It provides only a few methods, but is a very commonly used
622 class. The primary data tracked by the <tt>Instruction</tt> class itself is the
623 opcode (instruction type) and the parent <a
624 href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
625 into. To represent a specific type of instruction, one of many subclasses of
626 <tt>Instruction</tt> are used.<p>
628 Because the <tt>Instruction</tt> class subclasses the <a
629 href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
630 way as for other <a href="#User"><tt>User</tt></a>s (with the
631 <tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
632 <tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
635 <!-- _______________________________________________________________________ -->
636 </ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
637 the <tt>Instruction</tt> class</h4><ul>
639 <li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
641 Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
642 <tt>Instruction</tt> is embedded into.<p>
644 <li><tt>bool hasSideEffects()</tt><p>
646 Returns true if the instruction has side effects, i.e. it is a <tt>call</tt>,
647 <tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
649 <li><tt>unsigned getOpcode()</tt><p>
651 Returns the opcode for the <tt>Instruction</tt>.<p>
655 \subsection{Subclasses of Instruction :}
657 <li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
659 <li><tt>bool swapOperands()</tt>: Exchange the two operands to this instruction. If the instruction cannot be reversed (i.e. if it's a Div), it returns true.
661 <li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
663 <li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
664 <li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
665 <li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
668 <li>PHINode : This represents the PHI instructions in the SSA form.
670 <li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
671 <li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
672 <li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
673 <li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
674 <li><tt> void addIncoming(Value *D, BasicBlock *BB)</tt>:
675 Add an incoming value to the end of the PHI list
676 <li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
677 Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
679 <li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
680 <li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
682 <li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
684 <li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
686 <li><tt>Value * getPointerOperand ()</tt>: Returns the Pointer Operand which is typically the 0th operand.
688 <li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
690 <li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
691 <li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
692 <li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
700 <!-- ======================================================================= -->
701 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
702 <tr><td> </td><td width="100%">
703 <font color="#EEEEFF" face="Georgia,Palatino"><b>
704 <a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
705 </b></font></td></tr></table><ul>
708 href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
709 doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
710 Superclass: <a href="#Value"><tt>Value</tt></a><p>
713 This class represents a single entry multiple exit section of the code, commonly
714 known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
715 maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
716 the body of the block. Matching the language definition, the last element of
717 this list of instructions is always a terminator instruction (a subclass of the
718 <a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
720 In addition to tracking the list of instructions that make up the block, the
721 <tt>BasicBlock</tt> class also keeps track of the <a
722 href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
724 Note that <tt>BasicBlock</tt>s themselves are <a
725 href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
726 like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
730 <!-- _______________________________________________________________________ -->
731 </ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
732 the <tt>BasicBlock</tt> class</h4><ul>
734 <li><tt>BasicBlock(const std::string &Name = "", <a
735 href="#Function">Function</a> *Parent = 0)</tt><p>
737 The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
738 insertion into a function. The constructor simply takes a name for the new
739 block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
740 into. If the <tt>Parent</tt> parameter is specified, the new
741 <tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
742 href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
743 manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
745 <li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
746 <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
747 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
748 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
750 These methods and typedefs are forwarding functions that have the same semantics
751 as the standard library methods of the same names. These methods expose the
752 underlying instruction list of a basic block in a way that is easy to
753 manipulate. To get the full complement of container operations (including
754 operations to update the list), you must use the <tt>getInstList()</tt>
757 <li><tt>BasicBlock::InstListType &getInstList()</tt><p>
759 This method is used to get access to the underlying container that actually
760 holds the Instructions. This method must be used when there isn't a forwarding
761 function in the <tt>BasicBlock</tt> class for the operation that you would like
762 to perform. Because there are no forwarding functions for "updating"
763 operations, you need to use this if you want to update the contents of a
764 <tt>BasicBlock</tt>.<p>
766 <li><tt><A href="#Function">Function</a> *getParent()</tt><p>
768 Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
769 embedded into, or a null pointer if it is homeless.<p>
771 <li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
773 Returns a pointer to the terminator instruction that appears at the end of the
774 <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
775 instruction in the block is not a terminator, then a null pointer is
779 <!-- ======================================================================= -->
780 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
781 <tr><td> </td><td width="100%">
782 <font color="#EEEEFF" face="Georgia,Palatino"><b>
783 <a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
784 </b></font></td></tr></table><ul>
787 href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
788 doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
789 Superclasses: <a href="#User"><tt>User</tt></a>, <a
790 href="#Value"><tt>Value</tt></a><p>
792 Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
793 href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
794 visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
795 Because they are visible at global scope, they are also subject to linking with
796 other globals defined in different translation units. To control the linking
797 process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
798 <tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
800 If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
801 <tt>static</tt> in C), it is not visible to code outside the current translation
802 unit, and does not participate in linking. If it has external linkage, it is
803 visible to external code, and does participate in linking. In addition to
804 linkage information, <tt>GlobalValue</tt>s keep track of which <a
805 href="#Module"><tt>Module</tt></a> they are currently part of.<p>
807 Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
808 their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
809 always a pointer to its contents. This is explained in the LLVM Language
813 <!-- _______________________________________________________________________ -->
814 </ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
815 the <tt>GlobalValue</tt> class</h4><ul>
817 <li><tt>bool hasInternalLinkage() const</tt><br>
818 <tt>bool hasExternalLinkage() const</tt><br>
819 <tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
821 These methods manipulate the linkage characteristics of the
822 <tt>GlobalValue</tt>.<p>
824 <li><tt><a href="#Module">Module</a> *getParent()</tt><p>
826 This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
827 currently embedded into.<p>
831 <!-- ======================================================================= -->
832 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
833 <tr><td> </td><td width="100%">
834 <font color="#EEEEFF" face="Georgia,Palatino"><b>
835 <a name="Function">The <tt>Function</tt> class</a>
836 </b></font></td></tr></table><ul>
839 href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
840 doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
841 Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
842 href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
844 The <tt>Function</tt> class represents a single procedure in LLVM. It is
845 actually one of the more complex classes in the LLVM heirarchy because it must
846 keep track of a large amount of data. The <tt>Function</tt> class keeps track
847 of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
848 href="#Argument"><tt>Argument</tt></a>s, and a <a
849 href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
851 The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
852 used part of <tt>Function</tt> objects. The list imposes an implicit ordering
853 of the blocks in the function, which indicate how the code will be layed out by
854 the backend. Additionally, the first <a
855 href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
856 <tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
857 block. There are no implicit exit nodes, and in fact there may be multiple exit
858 nodes from a single <tt>Function</tt>. If the <a
859 href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
860 the <tt>Function</tt> is actually a function declaration: the actual body of the
861 function hasn't been linked in yet.<p>
863 In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
864 <tt>Function</tt> class also keeps track of the list of formal <a
865 href="#Argument"><tt>Argument</tt></a>s that the function receives. This
866 container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
867 nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
868 the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
870 The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
871 feature that is only used when you have to look up a value by name. Aside from
872 that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
873 make sure that there are not conflicts between the names of <a
874 href="#Instruction"><tt>Instruction</tt></a>s, <a
875 href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
876 href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
879 <!-- _______________________________________________________________________ -->
880 </ul><h4><a name="m_Function"><hr size=0>Important Public Members of
881 the <tt>Function</tt> class</h4><ul>
883 <li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &N = "")</tt><p>
885 Constructor used when you need to create new <tt>Function</tt>s to add the the
886 program. The constructor must specify the type of the function to create and
887 whether or not it should start out with internal or external linkage.<p>
889 <li><tt>bool isExternal()</tt><p>
891 Return whether or not the <tt>Function</tt> has a body defined. If the function
892 is "external", it does not have a body, and thus must be resolved by linking
893 with a function defined in a different translation unit.<p>
896 <li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
897 <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
898 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
899 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
901 These are forwarding methods that make it easy to access the contents of a
902 <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
905 <li><tt>Function::BasicBlockListType &getBasicBlockList()</tt><p>
907 Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
908 neccesary to use when you need to update the list or perform a complex action
909 that doesn't have a forwarding method.<p>
912 <li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
913 <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
914 <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
915 <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
917 These are forwarding methods that make it easy to access the contents of a
918 <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
920 <li><tt>Function::ArgumentListType &getArgumentList()</tt><p>
922 Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
923 neccesary to use when you need to update the list or perform a complex action
924 that doesn't have a forwarding method.<p>
928 <li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
930 Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
931 function. Because the entry block for the function is always the first block,
932 this returns the first block of the <tt>Function</tt>.<p>
934 <li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
935 <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
937 This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
938 and returns the return type of the function, or the <a
939 href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
942 <li><tt>bool hasSymbolTable() const</tt><p>
944 Return true if the <tt>Function</tt> has a symbol table allocated to it and if
945 there is at least one entry in it.<p>
947 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
949 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
950 <tt>Function</tt> or a null pointer if one has not been allocated (because there
951 are no named values in the function).<p>
953 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
955 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
956 <tt>Function</tt> or allocate a new <a
957 href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
958 should only be used when adding elements to the <a
959 href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
960 not left laying around.<p>
964 <!-- ======================================================================= -->
965 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
966 <tr><td> </td><td width="100%">
967 <font color="#EEEEFF" face="Georgia,Palatino"><b>
968 <a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
969 </b></font></td></tr></table><ul>
972 href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
973 doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
974 Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
975 href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
977 Global variables are represented with the (suprise suprise)
978 <tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
979 also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
980 are always referenced by their address (global values must live in memory, so
981 their "name" refers to their address). Global variables may have an initial
982 value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
983 have an initializer, they may be marked as "constant" themselves (indicating
984 that their contents never change at runtime).<p>
987 <!-- _______________________________________________________________________ -->
988 </ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
989 <tt>GlobalVariable</tt> class</h4><ul>
991 <li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
992 isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
993 &Name = "")</tt><p>
995 Create a new global variable of the specified type. If <tt>isConstant</tt> is
996 true then the global variable will be marked as unchanging for the program, and
997 if <tt>isInternal</tt> is true the resultant global variable will have internal
998 linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
1001 <li><tt>bool isConstant() const</tt><p>
1003 Returns true if this is a global variable is known not to be modified at
1007 <li><tt>bool hasInitializer()</tt><p>
1009 Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
1012 <li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
1014 Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
1015 this method if there is no initializer.<p>
1018 <!-- ======================================================================= -->
1019 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1020 <tr><td> </td><td width="100%">
1021 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1022 <a name="Module">The <tt>Module</tt> class</a>
1023 </b></font></td></tr></table><ul>
1026 href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
1027 doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
1029 The <tt>Module</tt> class represents the top level structure present in LLVM
1030 programs. An LLVM module is effectively either a translation unit of the
1031 original program or a combination of several translation units merged by the
1032 linker. The <tt>Module</tt> class keeps track of a list of <a
1033 href="#Function"><tt>Function</tt></a>s, a list of <a
1034 href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
1035 href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
1036 helpful member functions that try to make common operations easy.<p>
1039 <!-- _______________________________________________________________________ -->
1040 </ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
1041 <tt>Module</tt> class</h4><ul>
1043 <li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
1044 <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
1045 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1046 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1048 These are forwarding methods that make it easy to access the contents of a
1049 <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
1052 <li><tt>Module::FunctionListType &getFunctionList()</tt><p>
1054 Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
1055 neccesary to use when you need to update the list or perform a complex action
1056 that doesn't have a forwarding method.<p>
1058 <!-- Global Variable -->
1061 <li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
1062 <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
1063 <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
1064 <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
1066 These are forwarding methods that make it easy to access the contents of a
1067 <tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
1070 <li><tt>Module::GlobalListType &getGlobalList()</tt><p>
1072 Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
1073 This is neccesary to use when you need to update the list or perform a complex
1074 action that doesn't have a forwarding method.<p>
1077 <!-- Symbol table stuff -->
1080 <li><tt>bool hasSymbolTable() const</tt><p>
1082 Return true if the <tt>Module</tt> has a symbol table allocated to it and if
1083 there is at least one entry in it.<p>
1085 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1087 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1088 <tt>Module</tt> or a null pointer if one has not been allocated (because there
1089 are no named values in the function).<p>
1091 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
1093 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1094 <tt>Module</tt> or allocate a new <a
1095 href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
1096 should only be used when adding elements to the <a
1097 href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
1098 not left laying around.<p>
1101 <!-- Convenience methods -->
1104 <li><tt><a href="#Function">Function</a> *getFunction(const std::string &Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt><p>
1106 Look up the specified function in the <tt>Module</tt> <a
1107 href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
1111 <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
1112 &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
1114 Look up the specified function in the <tt>Module</tt> <a
1115 href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
1116 external declaration for the function and return it.<p>
1119 <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
1121 If there is at least one entry in the <a
1122 href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
1123 href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
1127 <li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
1130 Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
1131 <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
1132 is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
1136 <!-- ======================================================================= -->
1137 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1138 <tr><td> </td><td width="100%">
1139 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1140 <a name="Constant">The <tt>Constant</tt> class and subclasses</a>
1141 </b></font></td></tr></table><ul>
1143 Constant represents a base class for different types of constants. It is
1144 subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
1145 ConstantArray etc for representing the various types of Constants.<p>
1148 <!-- _______________________________________________________________________ -->
1149 </ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1151 <li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
1156 \subsection{Important Subclasses of Constant}
1158 <li>ConstantSInt : This subclass of Constant represents a signed integer constant.
1160 <li><tt>int64_t getValue () const</tt>: Returns the underlying value of this constant.
1162 <li>ConstantUInt : This class represents an unsigned integer.
1164 <li><tt>uint64_t getValue () const</tt>: Returns the underlying value of this constant.
1166 <li>ConstantFP : This class represents a floating point constant.
1168 <li><tt>double getValue () const</tt>: Returns the underlying value of this constant.
1170 <li>ConstantBool : This represents a boolean constant.
1172 <li><tt>bool getValue () const</tt>: Returns the underlying value of this constant.
1174 <li>ConstantArray : This represents a constant array.
1176 <li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1178 <li>ConstantStruct : This represents a constant struct.
1180 <li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1182 <li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
1184 <li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
1189 <!-- ======================================================================= -->
1190 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1191 <tr><td> </td><td width="100%">
1192 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1193 <a name="Type">The <tt>Type</tt> class and Derived Types</a>
1194 </b></font></td></tr></table><ul>
1196 Type as noted earlier is also a subclass of a Value class. Any primitive
1197 type (like int, short etc) in LLVM is an instance of Type Class. All
1198 other types are instances of subclasses of type like FunctionType,
1199 ArrayType etc. DerivedType is the interface for all such dervied types
1200 including FunctionType, ArrayType, PointerType, StructType. Types can have
1201 names. They can be recursive (StructType). There exists exactly one instance
1202 of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
1204 <!-- _______________________________________________________________________ -->
1205 </ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1207 <li><tt>PrimitiveID getPrimitiveID () const</tt>: Returns the base type of the type.
1208 <li><tt> bool isSigned () const</tt>: Returns whether an integral numeric type is signed. This is true for SByteTy, ShortTy, IntTy, LongTy. Note that this is not true for Float and Double.
1209 <li><tt>bool isUnsigned () const</tt>: Returns whether a numeric type is unsigned. This is not quite the complement of isSigned... nonnumeric types return false as they do with isSigned. This returns true for UByteTy, UShortTy, UIntTy, and ULongTy.
1210 <li><tt> bool isInteger () const</tt>: Equilivent to isSigned() || isUnsigned(), but with only a single virtual function invocation.
1211 <li><tt>bool isIntegral () const</tt>: Returns true if this is an integral type, which is either Bool type or one of the Integer types.
1213 <li><tt>bool isFloatingPoint ()</tt>: Return true if this is one of the two floating point types.
1214 <li><tt>bool isRecursive () const</tt>: Returns rue if the type graph contains a cycle.
1215 <li><tt>isLosslesslyConvertableTo (const Type *Ty) const</tt>: Return true if this type can be converted to 'Ty' without any reinterpretation of bits. For example, uint to int.
1216 <li><tt>bool isPrimitiveType () const</tt>: Returns true if it is a primitive type.
1217 <li><tt>bool isDerivedType () const</tt>: Returns true if it is a derived type.
1218 <li><tt>const Type * getContainedType (unsigned i) const</tt>:
1219 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.
1220 <li><tt>unsigned getNumContainedTypes () const</tt>: Return the number of types in the derived type.
1224 \subsection{Derived Types}
1226 <li>SequentialType : This is subclassed by ArrayType and PointerType
1228 <li><tt>const Type * getElementType () const</tt>: Returns the type of each of the elements in the sequential type.
1230 <li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
1232 <li><tt>unsigned getNumElements () const</tt>: Returns the number of elements in the array.
1234 <li>PointerType : Subclass of SequentialType for pointer types.
1235 <li>StructType : subclass of DerivedTypes for struct types
1236 <li>FunctionType : subclass of DerivedTypes for function types.
1239 <li><tt>bool isVarArg () const</tt>: Returns true if its a vararg function
1240 <li><tt> const Type * getReturnType () const</tt>: Returns the return type of the function.
1241 <li><tt> const ParamTypes &getParamTypes () const</tt>: Returns a vector of parameter types.
1242 <li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
1243 <li><tt> const unsigned getNumParams () const</tt>: Returns the number of formal parameters.
1250 <!-- ======================================================================= -->
1251 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1252 <tr><td> </td><td width="100%">
1253 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1254 <a name="Argument">The <tt>Argument</tt> class</a>
1255 </b></font></td></tr></table><ul>
1257 This subclass of Value defines the interface for incoming formal arguments to a
1258 function. A Function maitanis a list of its formal arguments. An argument has a
1259 pointer to the parent Function.
1264 <!-- *********************************************************************** -->
1266 <!-- *********************************************************************** -->
1269 <address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
1270 <a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1271 <!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
1272 <!-- hhmts start -->
1273 Last modified: Mon Sep 9 00:52:10 CDT 2002
1275 </font></body></html>