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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>The isa<>, cast<> and dyn_cast<> templates
17 <li><a href="#common">Helpful Hints for Common Operations</a>
19 <li><a href="#inspection">Basic Inspection and Traversal Routines</a>
21 <li><a href="#iterate_function">Iterating over the <tt>BasicBlock</tt>s
22 in a <tt>Function</tt></a>
23 <li><a href="#iterate_basicblock">Iterating over the <tt>Instruction</tt>s
24 in a <tt>BasicBlock</tt></a>
25 <li><a href="#iterate_institer">Iterating over the <tt>Instruction</tt>s
26 in a <tt>Function</tt></a>
27 <li><a href="#iterate_convert">Turning an iterator into a class
29 <li><a href="#iterate_complex">Finding call sites: a more complex
31 <li><a href="#iterate_chains">Iterating over def-use & use-def
34 <li><a href="#simplechanges">Making simple changes</a>
36 <li>Creating and inserting new <tt>Instruction</tt>s
37 <li>Deleting <tt>Instruction</tt>s
38 <li>Replacing an <tt>Instruction</tt> with another <tt>Value</tt>
41 <li>Working with the Control Flow Graph
43 <li>Accessing predecessors and successors of a <tt>BasicBlock</tt>
50 <li>isa<>, cast<>, and dyn_cast<> templates
52 <li>The general graph API
53 <li>The <tt>InstVisitor</tt> template
55 <li>The <tt>Statistic</tt> template
59 <li>Useful related topics
61 <li>The <tt>-time-passes</tt> option
62 <li>How to use the LLVM Makefile system
63 <li>How to write a regression test
68 <li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
70 <li><a href="#Value">The <tt>Value</tt> class</a>
72 <li><a href="#User">The <tt>User</tt> class</a>
74 <li><a href="#Instruction">The <tt>Instruction</tt> class</a>
78 <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
80 <li><a href="#BasicBlock">The <tt>BasicBlock</tt> class</a>
81 <li><a href="#Function">The <tt>Function</tt> class</a>
82 <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a>
84 <li><a href="#Module">The <tt>Module</tt> class</a>
85 <li><a href="#Constant">The <tt>Constant</tt> class</a>
91 <li><a href="#Type">The <tt>Type</tt> class</a>
92 <li><a href="#Argument">The <tt>Argument</tt> class</a>
94 <li>The <tt>SymbolTable</tt> class
95 <li>The <tt>ilist</tt> and <tt>iplist</tt> classes
97 <li>Creating, inserting, moving and deleting from LLVM lists
99 <li>Important iterator invalidation semantics to be aware of
102 <p><b>Written by <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a>
103 <a href="mailto:sabre@nondot.org">Chris Lattner</a>, and
104 <a href="mailto:jstanley@cs.uiuc.edu">Joel Stanley</a></b><p>
108 <!-- *********************************************************************** -->
109 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
110 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
111 <a name="introduction">Introduction
112 </b></font></td></tr></table><ul>
113 <!-- *********************************************************************** -->
115 This document is meant to highlight some of the important classes and interfaces
116 available in the LLVM source-base. This manual is not intended to explain what
117 LLVM is, how it works, and what LLVM code looks like. It assumes that you know
118 the basics of LLVM and are interested in writing transformations or otherwise
119 analyzing or manipulating the code.<p>
121 This document should get you oriented so that you can find your way in the
122 continuously growing source code that makes up the LLVM infrastructure. Note
123 that this manual is not intended to serve as a replacement for reading the
124 source code, so if you think there should be a method in one of these classes to
125 do something, but it's not listed, check the source. Links to the <a
126 href="/doxygen/">doxygen</a> sources are provided to make this as easy as
129 The first section of this document describes general information that is useful
130 to know when working in the LLVM infrastructure, and the second describes the
131 Core LLVM classes. In the future this manual will be extended with information
132 describing how to use extension libraries, such as dominator information, CFG
133 traversal routines, and useful utilities like the <tt><a
134 href="/doxygen/InstVisitor_8h-source.html">InstVisitor</a></tt> template.<p>
137 <!-- *********************************************************************** -->
138 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
139 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
140 <a name="general">General Information
141 </b></font></td></tr></table><ul>
142 <!-- *********************************************************************** -->
144 This section contains general information that is useful if you are working in
145 the LLVM source-base, but that isn't specific to any particular API.<p>
148 <!-- ======================================================================= -->
149 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
150 <tr><td> </td><td width="100%">
151 <font color="#EEEEFF" face="Georgia,Palatino"><b>
152 <a name="stl">The C++ Standard Template Library</a>
153 </b></font></td></tr></table><ul>
155 LLVM makes heavy use of the C++ Standard Template Library (STL), perhaps much
156 more than you are used to, or have seen before. Because of this, you might want
157 to do a little background reading in the techniques used and capabilities of the
158 library. There are many good pages that discuss the STL, and several books on
159 the subject that you can get, so it will not be discussed in this document.<p>
161 Here are some useful links:<p>
163 <li><a href="http://www.dinkumware.com/htm_cpl/index.html">Dinkumware C++
164 Library reference</a> - an excellent reference for the STL and other parts of
165 the standard C++ library.<br>
167 <li><a href="http://www.parashift.com/c++-faq-lite/">C++ Frequently Asked
170 <li><a href="http://www.sgi.com/tech/stl/">SGI's STL Programmer's Guide</a> -
172 href="http://www.sgi.com/tech/stl/stl_introduction.html">Introduction to the
175 <li><a href="http://www.research.att.com/~bs/C++.html">Bjarne Stroustrup's C++
180 You are also encouraged to take a look at the <a
181 href="CodingStandards.html">LLVM Coding Standards</a> guide which focuses on how
182 to write maintainable code more than where to put your curly braces.<p>
186 <!-- *********************************************************************** -->
187 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
188 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
189 <a name="common">Helpful Hints for Common Operations
190 </b></font></td></tr></table><ul>
191 <!-- *********************************************************************** -->
193 This section describes how to perform some very simple transformations of LLVM
194 code. This is meant to give examples of common idioms used, showing the
195 practical side of LLVM transformations.<p>
197 Because this is a "how-to" section, you should also read about the main classes
198 that you will be working with. The <a href="#coreclasses">Core LLVM Class
199 Hierarchy Reference</a> contains details and descriptions of the main classes
200 that you should know about.<p>
202 <!-- NOTE: this section should be heavy on example code -->
205 <!-- ======================================================================= -->
206 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
207 <tr><td> </td><td width="100%">
208 <font color="#EEEEFF" face="Georgia,Palatino"><b>
209 <a name="inspection">Basic Inspection and Traversal Routines</a>
210 </b></font></td></tr></table><ul>
213 <!-- LLVM has heirarchical representation: Module, Function, BasicBlock,
214 Instruction. Common patterns for all levels. -->
216 <!-- _______________________________________________________________________ -->
217 </ul><h4><a name="iterate_function"><hr size=0>Iterating over the
218 <tt>BasicBlock</tt>s in a <tt>Function</tt> </h4><ul>
220 It's quite common to have a <tt>Function</tt> instance that you'd like
221 to transform in some way; in particular, you'd like to manipulate its
222 <tt>BasicBlock</tt>s. To facilitate this, you'll need to iterate over
223 all of the <tt>BasicBlock</tt>s that constitute the <tt>Function</tt>.
224 The following is an example that prints the name of a
225 <tt>BasicBlock</tt> and the number of <tt>Instruction</tt>s it
229 // func is a pointer to a Function instance
230 for(Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {
232 // print out the name of the basic block if it has one, and then the
233 // number of instructions that it contains
235 cerr << "Basic block (name=" << i->getName() << ") has "
236 << i->size() << " instructions.\n";
240 Note that i can be used as if it were a pointer for the purposes of
241 invoking member functions of the <tt>Instruction</tt> class. This is
242 because the indirection operator is overloaded for the iterator
243 classes. In the above code, the expression <tt>i->size()</tt> is
244 exactly equivalent to <tt>(*i).size()</tt> just like you'd expect.
246 <!-- _______________________________________________________________________ -->
247 </ul><h4><a name="iterate_basicblock"><hr size=0>Iterating over the
248 <tt>Instruction</tt>s in a <tt>BasicBlock</tt> </h4><ul>
250 Just like when dealing with <tt>BasicBlock</tt>s in
251 <tt>Function</tt>s, it's easy to iterate over the individual
252 instructions that make up <tt>BasicBlock</tt>s. Here's a code snippet
253 that prints out each instruction in a <tt>BasicBlock</tt>:
256 // blk is a pointer to a BasicBlock instance
257 for(BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i) {
258 // the next statement works since operator<<(ostream&,...)
259 // is overloaded for Instruction&
260 cerr << *i << endl;
263 However, this isn't really the best way to print out the contents of a
264 <tt>BasicBlock</tt>! Since the ostream operators are overloaded for
265 virtually anything you'll care about, you could have just invoked the
266 print routine on the basic block itself: <tt>cerr << *blk <<
269 Note that currently operator<< is implemented for <tt>Value*</tt>, so it
270 will print out the contents of the pointer, instead of
271 the pointer value you might expect. This is a deprecated interface that will
272 be removed in the future, so it's best not to depend on it. To print out the
273 pointer value for now, you must cast to <tt>void*</tt>.<p>
275 <!-- _______________________________________________________________________ -->
276 </ul><h4><a name="iterate_institer"><hr size=0>Iterating over the
277 <tt>Instruction</tt>s in a <tt>Function</tt></h4><ul>
279 <!-- Using llvm/Support/InstIterator.h to directly get at the instructions in a
282 Warning: *I returns an Instruction*, not an Instruction&
288 <!-- _______________________________________________________________________ -->
289 </ul><h4><a name="iterate_convert"><hr size=0>Turning an iterator into a class
292 Sometimes, it'll be useful to grab a reference (or pointer) to a class
293 instance when all you've got at hand is an iterator. Well, extracting
294 a reference or a pointer from an iterator is very straightforward.
295 Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and
296 <tt>j</tt> is a <tt>BasicBlock::const_iterator</tt>:
299 Instruction& inst = *i; // grab reference to instruction reference
300 Instruction* pinst = &*i; // grab pointer to instruction reference
301 const Instruction& inst = *j;
303 However, the iterators you'll be working with in the LLVM framework
304 are special: they will automatically convert to a ptr-to-instance type
305 whenever they need to. Instead of dereferencing the iterator and then
306 taking the address of the result, you can simply assign the iterator
307 to the proper pointer type and you get the dereference and address-of
308 operation as a result of the assignment (behind the scenes, this is a
309 result of overloading casting mechanisms). Thus the last line of the
312 <pre>Instruction* pinst = &*i;</pre>
314 is semantically equivalent to
316 <pre>Instruction* pinst = i;</pre>
318 <b>Caveat emptor</b>: The above syntax works <i>only</i> when you're
319 <i>not</i> working with <tt>dyn_cast</tt>. The template definition of
320 <tt>dyn_cast</tt> isn't implemented to handle this yet, so you'll
321 still need the following in order for things to work properly:
324 BasicBlock::iterator bbi = ...;
325 BranchInst* b = dyn_cast<BranchInst>(&*bbi);
328 The following code snippet illustrates use of the conversion
329 constructors provided by LLVM iterators. By using these, you can
330 explicitly grab the iterator of something without actually obtaining
331 it via iteration over some structure:
334 void printNextInstruction(Instruction* inst) {
335 BasicBlock::iterator it(inst);
336 ++it; // after this line, it refers to the instruction after *inst.
337 if(it != inst->getParent()->end()) cerr << *it << endl;
340 Of course, this example is strictly pedagogical, because it'd be much
341 better to explicitly grab the next instruction directly from inst.
343 <!-- dereferenced iterator = Class &
344 iterators have converting constructor for 'Class *'
345 iterators automatically convert to 'Class *' except in dyn_cast<> case
348 <!--_______________________________________________________________________-->
349 </ul><h4><a name="iterate_complex"><hr size=0>Finding call sites: a slightly
350 more complex example </h4><ul>
352 Say that you're writing a FunctionPass and would like to count all the
353 locations in the entire module (that is, across every <tt>Function</tt>)
354 where a certain function named foo (that takes an int and returns an
355 int) is called. As you'll learn later, you may want to use an
356 <tt>InstVisitor</tt> to accomplish this in a much more straightforward
357 manner, but this example will allow us to explore how you'd do it if
358 you didn't have <tt>InstVisitor</tt> around. In pseudocode, this is
362 initialize callCounter to zero
363 for each Function f in the Module
364 for each BasicBlock b in f
365 for each Instruction i in b
366 if(i is a CallInst and foo is the function it calls)
367 increment callCounter
370 And the actual code is (remember, since we're writing a
371 <tt>FunctionPass</tt> our <tt>FunctionPass</tt>-derived class simply
372 has to override the <tt>runOnFunction</tt> method...):
376 // Assume callCounter is a private member of the pass class being written,
377 // and has been initialized in the pass class constructor.
379 virtual runOnFunction(Function& F) {
381 // Remember, we assumed that the signature of foo was "int foo(int)";
382 // the first thing we'll do is grab the pointer to that function (as a
383 // Function*) so we can use it later when we're examining the
384 // parameters of a CallInst. All of the code before the call to
385 // Module::getOrInsertFunction() is in preparation to do symbol-table
386 // to find the function pointer.
388 vector<const Type*> params;
389 params.push_back(Type::IntTy);
390 const FunctionType* fooType = FunctionType::get(Type::IntTy, params);
391 Function* foo = F.getParent()->getOrInsertFunction("foo", fooType);
393 // Start iterating and (as per the pseudocode), increment callCounter.
395 for(Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
396 for(BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {
397 if(CallInst* callInst = dyn_cast<CallInst>(&*inst)) {
398 // we know we've encountered a call instruction, so we
399 // need to determine if it's a call to foo or not
401 if(callInst->getCalledFunction() == foo)
409 We could then print out the value of callCounter (if we wanted to)
410 inside the doFinalization method of our FunctionPass.
413 <!--_______________________________________________________________________-->
414 </ul><h4><a name="iterate_chains"><hr size=0>Iterating over def-use &
415 use-def chains</h4><ul>
419 def-use chains ("finding all users of"): Value::use_begin/use_end
420 use-def chains ("finding all values used"): User::op_begin/op_end [op=operand]
423 <!-- ======================================================================= -->
424 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
425 <tr><td> </td><td width="100%">
426 <font color="#EEEEFF" face="Georgia,Palatino"><b>
427 <a name="simplechanges">Making simple changes</a>
428 </b></font></td></tr></table><ul>
430 <!-- Value::replaceAllUsesWith
431 User::replaceUsesOfWith
432 Point out: include/llvm/Transforms/Utils/
433 especially BasicBlockUtils.h with:
434 ReplaceInstWithValue, ReplaceInstWithInst
439 <!-- *********************************************************************** -->
440 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
441 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
442 <a name="coreclasses">The Core LLVM Class Hierarchy Reference
443 </b></font></td></tr></table><ul>
444 <!-- *********************************************************************** -->
446 The Core LLVM classes are the primary means of representing the program being
447 inspected or transformed. The core LLVM classes are defined in header files in
448 the <tt>include/llvm/</tt> directory, and implemented in the <tt>lib/VMCore</tt>
452 <!-- ======================================================================= -->
453 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
454 <tr><td> </td><td width="100%">
455 <font color="#EEEEFF" face="Georgia,Palatino"><b>
456 <a name="Value">The <tt>Value</tt> class</a>
457 </b></font></td></tr></table><ul>
459 <tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt></b><br>
460 doxygen info: <a href="/doxygen/classValue.html">Value Class</a><p>
463 The <tt>Value</tt> class is the most important class in LLVM Source base. It
464 represents a typed value that may be used (among other things) as an operand to
465 an instruction. There are many different types of <tt>Value</tt>s, such as <a
466 href="#Constant"><tt>Constant</tt></a>s, <a
467 href="#Argument"><tt>Argument</tt></a>s, and even <a
468 href="#Instruction"><tt>Instruction</tt></a>s and <a
469 href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.<p>
471 A particular <tt>Value</tt> may be used many times in the LLVM representation
472 for a program. For example, an incoming argument to a function (represented
473 with an instance of the <a href="#Argument">Argument</a> class) is "used" by
474 every instruction in the function that references the argument. To keep track
475 of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
476 href="#User"><tt>User</tt></a>s that is using it (the <a
477 href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
478 graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
479 def-use information in the program, and is accessible through the <tt>use_</tt>*
480 methods, shown below.<p>
482 Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed, and
483 this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
484 method. <a name="#nameWarning">In addition, all LLVM values can be named. The
485 "name" of the <tt>Value</tt> is symbolic string printed in the LLVM code:<p>
488 %<b>foo</b> = add int 1, 2
491 The name of this instruction is "foo". <b>NOTE</b> that the name of any value
492 may be missing (an empty string), so names should <b>ONLY</b> be used for
493 debugging (making the source code easier to read, debugging printouts), they
494 should not be used to keep track of values or map between them. For this
495 purpose, use a <tt>std::map</tt> of pointers to the <tt>Value</tt> itself
498 One important aspect of LLVM is that there is no distinction between an SSA
499 variable and the operation that produces it. Because of this, any reference to
500 the value produced by an instruction (or the value available as an incoming
501 argument, for example) is represented as a direct pointer to the class that
502 represents this value. Although this may take some getting used to, it
503 simplifies the representation and makes it easier to manipulate.<p>
506 <!-- _______________________________________________________________________ -->
507 </ul><h4><a name="m_Value"><hr size=0>Important Public Members of
508 the <tt>Value</tt> class</h4><ul>
510 <li><tt>Value::use_iterator</tt> - Typedef for iterator over the use-list<br>
511 <tt>Value::use_const_iterator</tt>
512 - Typedef for const_iterator over the use-list<br>
513 <tt>unsigned use_size()</tt> - Returns the number of users of the value.<br>
514 <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
515 <tt>use_iterator use_begin()</tt>
516 - Get an iterator to the start of the use-list.<br>
517 <tt>use_iterator use_end()</tt>
518 - Get an iterator to the end of the use-list.<br>
519 <tt><a href="#User">User</a> *use_back()</tt>
520 - Returns the last element in the list.<p>
522 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>
524 <li><tt><a href="#Type">Type</a> *getType() const</tt><p>
525 This method returns the Type of the Value.
527 <li><tt>bool hasName() const</tt><br>
528 <tt>std::string getName() const</tt><br>
529 <tt>void setName(const std::string &Name)</tt><p>
531 This family of methods is used to access and assign a name to a <tt>Value</tt>,
532 be aware of the <a href="#nameWarning">precaution above</a>.<p>
535 <li><tt>void replaceAllUsesWith(Value *V)</tt><p>
537 This method traverses the use list of a <tt>Value</tt> changing all <a
538 href="#User"><tt>User</tt>'s</a> of the current value to refer to "<tt>V</tt>"
539 instead. For example, if you detect that an instruction always produces a
540 constant value (for example through constant folding), you can replace all uses
541 of the instruction with the constant like this:<p>
544 Inst->replaceAllUsesWith(ConstVal);
549 <!-- ======================================================================= -->
550 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
551 <tr><td> </td><td width="100%">
552 <font color="#EEEEFF" face="Georgia,Palatino"><b>
553 <a name="User">The <tt>User</tt> class</a>
554 </b></font></td></tr></table><ul>
556 <tt>#include "<a href="/doxygen/User_8h-source.html">llvm/User.h</a>"</tt></b><br>
557 doxygen info: <a href="/doxygen/classUser.html">User Class</a><br>
558 Superclass: <a href="#Value"><tt>Value</tt></a><p>
561 The <tt>User</tt> class is the common base class of all LLVM nodes that may
562 refer to <a href="#Value"><tt>Value</tt></a>s. It exposes a list of "Operands"
563 that are all of the <a href="#Value"><tt>Value</tt></a>s that the User is
564 referring to. The <tt>User</tt> class itself is a subclass of
567 The operands of a <tt>User</tt> point directly to the LLVM <a
568 href="#Value"><tt>Value</tt></a> that it refers to. Because LLVM uses Static
569 Single Assignment (SSA) form, there can only be one definition referred to,
570 allowing this direct connection. This connection provides the use-def
571 information in LLVM.<p>
573 <!-- _______________________________________________________________________ -->
574 </ul><h4><a name="m_User"><hr size=0>Important Public Members of
575 the <tt>User</tt> class</h4><ul>
577 The <tt>User</tt> class exposes the operand list in two ways: through an index
578 access interface and through an iterator based interface.<p>
580 <li><tt>Value *getOperand(unsigned i)</tt><br>
581 <tt>unsigned getNumOperands()</tt><p>
583 These two methods expose the operands of the <tt>User</tt> in a convenient form
584 for direct access.<p>
586 <li><tt>User::op_iterator</tt> - Typedef for iterator over the operand list<br>
587 <tt>User::op_const_iterator</tt>
588 <tt>use_iterator op_begin()</tt>
589 - Get an iterator to the start of the operand list.<br>
590 <tt>use_iterator op_end()</tt>
591 - Get an iterator to the end of the operand list.<p>
593 Together, these methods make up the iterator based interface to the operands of
598 <!-- ======================================================================= -->
599 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
600 <tr><td> </td><td width="100%">
601 <font color="#EEEEFF" face="Georgia,Palatino"><b>
602 <a name="Instruction">The <tt>Instruction</tt> class</a>
603 </b></font></td></tr></table><ul>
606 href="/doxygen/Instruction_8h-source.html">llvm/Instruction.h</a>"</tt></b><br>
607 doxygen info: <a href="/doxygen/classInstruction.html">Instruction Class</a><br>
608 Superclasses: <a href="#User"><tt>User</tt></a>, <a
609 href="#Value"><tt>Value</tt></a><p>
611 The <tt>Instruction</tt> class is the common base class for all LLVM
612 instructions. It provides only a few methods, but is a very commonly used
613 class. The primary data tracked by the <tt>Instruction</tt> class itself is the
614 opcode (instruction type) and the parent <a
615 href="#BasicBlock"><tt>BasicBlock</tt></a> the <tt>Instruction</tt> is embedded
616 into. To represent a specific type of instruction, one of many subclasses of
617 <tt>Instruction</tt> are used.<p>
619 Because the <tt>Instruction</tt> class subclasses the <a
620 href="#User"><tt>User</tt></a> class, its operands can be accessed in the same
621 way as for other <a href="#User"><tt>User</tt></a>s (with the
622 <tt>getOperand()</tt>/<tt>getNumOperands()</tt> and
623 <tt>op_begin()</tt>/<tt>op_end()</tt> methods).<p>
626 <!-- _______________________________________________________________________ -->
627 </ul><h4><a name="m_Instruction"><hr size=0>Important Public Members of
628 the <tt>Instruction</tt> class</h4><ul>
630 <li><tt><a href="#BasicBlock">BasicBlock</a> *getParent()</tt><p>
632 Returns the <a href="#BasicBlock"><tt>BasicBlock</tt></a> that this
633 <tt>Instruction</tt> is embedded into.<p>
635 <li><tt>bool hasSideEffects()</tt><p>
637 Returns true if the instruction has side effects, i.e. it is a <tt>call</tt>,
638 <tt>free</tt>, <tt>invoke</tt>, or <tt>store</tt>.<p>
640 <li><tt>unsigned getOpcode()</tt><p>
642 Returns the opcode for the <tt>Instruction</tt>.<p>
646 \subsection{Subclasses of Instruction :}
648 <li>BinaryOperator : This subclass of Instruction defines a general interface to the all the instructions involvong binary operators in LLVM.
650 <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.
652 <li>TerminatorInst : This subclass of Instructions defines an interface for all instructions that can terminate a BasicBlock.
654 <li> <tt>unsigned getNumSuccessors()</tt>: Returns the number of successors for this terminator instruction.
655 <li><tt>BasicBlock *getSuccessor(unsigned i)</tt>: As the name suggests returns the ith successor BasicBlock.
656 <li><tt>void setSuccessor(unsigned i, BasicBlock *B)</tt>: sets BasicBlock B as the ith succesor to this terminator instruction.
659 <li>PHINode : This represents the PHI instructions in the SSA form.
661 <li><tt> unsigned getNumIncomingValues()</tt>: Returns the number of incoming edges to this PHI node.
662 <li><tt> Value *getIncomingValue(unsigned i)</tt>: Returns the ith incoming Value.
663 <li><tt>void setIncomingValue(unsigned i, Value *V)</tt>: Sets the ith incoming Value as V
664 <li><tt>BasicBlock *getIncomingBlock(unsigned i)</tt>: Returns the Basic Block corresponding to the ith incoming Value.
665 <li><tt> void addIncoming(Value *D, BasicBlock *BB)</tt>:
666 Add an incoming value to the end of the PHI list
667 <li><tt> int getBasicBlockIndex(const BasicBlock *BB) const</tt>:
668 Returns the first index of the specified basic block in the value list for this PHI. Returns -1 if no instance.
670 <li>CastInst : In LLVM all casts have to be done through explicit cast instructions. CastInst defines the interface to the cast instructions.
671 <li>CallInst : This defines an interface to the call instruction in LLVM. ARguments to the function are nothing but operands of the instruction.
673 <li>: <tt>Function *getCalledFunction()</tt>: Returns a handle to the function that is being called by this Function.
675 <li>LoadInst, StoreInst, GetElemPtrInst : These subclasses represent load, store and getelementptr instructions in LLVM.
677 <li><tt>Value * getPointerOperand ()</tt>: Returns the Pointer Operand which is typically the 0th operand.
679 <li>BranchInst : This is a subclass of TerminatorInst and defines the interface for conditional and unconditional branches in LLVM.
681 <li><tt>bool isConditional()</tt>: Returns true if the branch is a conditional branch else returns false
682 <li> <tt>Value *getCondition()</tt>: Returns the condition if it is a conditional branch else returns null.
683 <li> <tt>void setUnconditionalDest(BasicBlock *Dest)</tt>: Changes the current branch to an unconditional one targetting the specified block.
691 <!-- ======================================================================= -->
692 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
693 <tr><td> </td><td width="100%">
694 <font color="#EEEEFF" face="Georgia,Palatino"><b>
695 <a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
696 </b></font></td></tr></table><ul>
699 href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt></b><br>
700 doxygen info: <a href="/doxygen/classBasicBlock.html">BasicBlock Class</a><br>
701 Superclass: <a href="#Value"><tt>Value</tt></a><p>
704 This class represents a single entry multiple exit section of the code, commonly
705 known as a basic block by the compiler community. The <tt>BasicBlock</tt> class
706 maintains a list of <a href="#Instruction"><tt>Instruction</tt></a>s, which form
707 the body of the block. Matching the language definition, the last element of
708 this list of instructions is always a terminator instruction (a subclass of the
709 <a href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).<p>
711 In addition to tracking the list of instructions that make up the block, the
712 <tt>BasicBlock</tt> class also keeps track of the <a
713 href="#Function"><tt>Function</tt></a> that it is embedded into.<p>
715 Note that <tt>BasicBlock</tt>s themselves are <a
716 href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
717 like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
721 <!-- _______________________________________________________________________ -->
722 </ul><h4><a name="m_BasicBlock"><hr size=0>Important Public Members of
723 the <tt>BasicBlock</tt> class</h4><ul>
725 <li><tt>BasicBlock(const std::string &Name = "", <a
726 href="#Function">Function</a> *Parent = 0)</tt><p>
728 The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
729 insertion into a function. The constructor simply takes a name for the new
730 block, and optionally a <a href="#Function"><tt>Function</tt></a> to insert it
731 into. If the <tt>Parent</tt> parameter is specified, the new
732 <tt>BasicBlock</tt> is automatically inserted at the end of the specified <a
733 href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
734 manually inserted into the <a href="#Function"><tt>Function</tt></a>.<p>
736 <li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
737 <tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
738 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
739 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
741 These methods and typedefs are forwarding functions that have the same semantics
742 as the standard library methods of the same names. These methods expose the
743 underlying instruction list of a basic block in a way that is easy to
744 manipulate. To get the full complement of container operations (including
745 operations to update the list), you must use the <tt>getInstList()</tt>
748 <li><tt>BasicBlock::InstListType &getInstList()</tt><p>
750 This method is used to get access to the underlying container that actually
751 holds the Instructions. This method must be used when there isn't a forwarding
752 function in the <tt>BasicBlock</tt> class for the operation that you would like
753 to perform. Because there are no forwarding functions for "updating"
754 operations, you need to use this if you want to update the contents of a
755 <tt>BasicBlock</tt>.<p>
757 <li><tt><A href="#Function">Function</a> *getParent()</tt><p>
759 Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
760 embedded into, or a null pointer if it is homeless.<p>
762 <li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt><p>
764 Returns a pointer to the terminator instruction that appears at the end of the
765 <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
766 instruction in the block is not a terminator, then a null pointer is
770 <!-- ======================================================================= -->
771 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
772 <tr><td> </td><td width="100%">
773 <font color="#EEEEFF" face="Georgia,Palatino"><b>
774 <a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
775 </b></font></td></tr></table><ul>
778 href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt></b><br>
779 doxygen info: <a href="/doxygen/classGlobalValue.html">GlobalValue Class</a><br>
780 Superclasses: <a href="#User"><tt>User</tt></a>, <a
781 href="#Value"><tt>Value</tt></a><p>
783 Global values (<A href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
784 href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
785 visible in the bodies of all <a href="#Function"><tt>Function</tt></a>s.
786 Because they are visible at global scope, they are also subject to linking with
787 other globals defined in different translation units. To control the linking
788 process, <tt>GlobalValue</tt>s know their linkage rules. Specifically,
789 <tt>GlobalValue</tt>s know whether they have internal or external linkage.<p>
791 If a <tt>GlobalValue</tt> has internal linkage (equivalent to being
792 <tt>static</tt> in C), it is not visible to code outside the current translation
793 unit, and does not participate in linking. If it has external linkage, it is
794 visible to external code, and does participate in linking. In addition to
795 linkage information, <tt>GlobalValue</tt>s keep track of which <a
796 href="#Module"><tt>Module</tt></a> they are currently part of.<p>
798 Because <tt>GlobalValue</tt>s are memory objects, they are always referred to by
799 their address. As such, the <a href="#Type"><tt>Type</tt></a> of a global is
800 always a pointer to its contents. This is explained in the LLVM Language
804 <!-- _______________________________________________________________________ -->
805 </ul><h4><a name="m_GlobalValue"><hr size=0>Important Public Members of
806 the <tt>GlobalValue</tt> class</h4><ul>
808 <li><tt>bool hasInternalLinkage() const</tt><br>
809 <tt>bool hasExternalLinkage() const</tt><br>
810 <tt>void setInternalLinkage(bool HasInternalLinkage)</tt><p>
812 These methods manipulate the linkage characteristics of the
813 <tt>GlobalValue</tt>.<p>
815 <li><tt><a href="#Module">Module</a> *getParent()</tt><p>
817 This returns the <a href="#Module"><tt>Module</tt></a> that the GlobalValue is
818 currently embedded into.<p>
822 <!-- ======================================================================= -->
823 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
824 <tr><td> </td><td width="100%">
825 <font color="#EEEEFF" face="Georgia,Palatino"><b>
826 <a name="Function">The <tt>Function</tt> class</a>
827 </b></font></td></tr></table><ul>
830 href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt></b><br>
831 doxygen info: <a href="/doxygen/classFunction.html">Function Class</a><br>
832 Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
833 href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
835 The <tt>Function</tt> class represents a single procedure in LLVM. It is
836 actually one of the more complex classes in the LLVM heirarchy because it must
837 keep track of a large amount of data. The <tt>Function</tt> class keeps track
838 of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
839 href="#Argument"><tt>Argument</tt></a>s, and a <a
840 href="#SymbolTable"><tt>SymbolTable</tt></a>.<p>
842 The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most commonly
843 used part of <tt>Function</tt> objects. The list imposes an implicit ordering
844 of the blocks in the function, which indicate how the code will be layed out by
845 the backend. Additionally, the first <a
846 href="#BasicBlock"><tt>BasicBlock</tt></a> is the implicit entry node for the
847 <tt>Function</tt>. It is not legal in LLVM explicitly branch to this initial
848 block. There are no implicit exit nodes, and in fact there may be multiple exit
849 nodes from a single <tt>Function</tt>. If the <a
850 href="#BasicBlock"><tt>BasicBlock</tt></a> list is empty, this indicates that
851 the <tt>Function</tt> is actually a function declaration: the actual body of the
852 function hasn't been linked in yet.<p>
854 In addition to a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, the
855 <tt>Function</tt> class also keeps track of the list of formal <a
856 href="#Argument"><tt>Argument</tt></a>s that the function receives. This
857 container manages the lifetime of the <a href="#Argument"><tt>Argument</tt></a>
858 nodes, just like the <a href="#BasicBlock"><tt>BasicBlock</tt></a> list does for
859 the <a href="#BasicBlock"><tt>BasicBlock</tt></a>s.<p>
861 The <a href="#SymbolTable"><tt>SymbolTable</tt></a> is a very rarely used LLVM
862 feature that is only used when you have to look up a value by name. Aside from
863 that, the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is used internally to
864 make sure that there are not conflicts between the names of <a
865 href="#Instruction"><tt>Instruction</tt></a>s, <a
866 href="#BasicBlock"><tt>BasicBlock</tt></a>s, or <a
867 href="#Argument"><tt>Argument</tt></a>s in the function body.<p>
870 <!-- _______________________________________________________________________ -->
871 </ul><h4><a name="m_Function"><hr size=0>Important Public Members of
872 the <tt>Function</tt> class</h4><ul>
874 <li><tt>Function(const <a href="#FunctionType">FunctionType</a> *Ty, bool isInternal, const std::string &N = "")</tt><p>
876 Constructor used when you need to create new <tt>Function</tt>s to add the the
877 program. The constructor must specify the type of the function to create and
878 whether or not it should start out with internal or external linkage.<p>
880 <li><tt>bool isExternal()</tt><p>
882 Return whether or not the <tt>Function</tt> has a body defined. If the function
883 is "external", it does not have a body, and thus must be resolved by linking
884 with a function defined in a different translation unit.<p>
887 <li><tt>Function::iterator</tt> - Typedef for basic block list iterator<br>
888 <tt>Function::const_iterator</tt> - Typedef for const_iterator.<br>
889 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
890 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
892 These are forwarding methods that make it easy to access the contents of a
893 <tt>Function</tt> object's <a href="#BasicBlock"><tt>BasicBlock</tt></a>
896 <li><tt>Function::BasicBlockListType &getBasicBlockList()</tt><p>
898 Returns the list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s. This is
899 neccesary to use when you need to update the list or perform a complex action
900 that doesn't have a forwarding method.<p>
903 <li><tt>Function::aiterator</tt> - Typedef for the argument list iterator<br>
904 <tt>Function::const_aiterator</tt> - Typedef for const_iterator.<br>
905 <tt>abegin()</tt>, <tt>aend()</tt>, <tt>afront()</tt>, <tt>aback()</tt>,
906 <tt>asize()</tt>, <tt>aempty()</tt>, <tt>arbegin()</tt>, <tt>arend()</tt><p>
908 These are forwarding methods that make it easy to access the contents of a
909 <tt>Function</tt> object's <a href="#Argument"><tt>Argument</tt></a> list.<p>
911 <li><tt>Function::ArgumentListType &getArgumentList()</tt><p>
913 Returns the list of <a href="#Argument"><tt>Argument</tt></a>s. This is
914 neccesary to use when you need to update the list or perform a complex action
915 that doesn't have a forwarding method.<p>
919 <li><tt><a href="#BasicBlock">BasicBlock</a> &getEntryNode()</tt><p>
921 Returns the entry <a href="#BasicBlock"><tt>BasicBlock</tt></a> for the
922 function. Because the entry block for the function is always the first block,
923 this returns the first block of the <tt>Function</tt>.<p>
925 <li><tt><a href="#Type">Type</a> *getReturnType()</tt><br>
926 <tt><a href="#FunctionType">FunctionType</a> *getFunctionType()</tt><p>
928 This traverses the <a href="#Type"><tt>Type</tt></a> of the <tt>Function</tt>
929 and returns the return type of the function, or the <a
930 href="#FunctionType"><tt>FunctionType</tt></a> of the actual function.<p>
933 <li><tt>bool hasSymbolTable() const</tt><p>
935 Return true if the <tt>Function</tt> has a symbol table allocated to it and if
936 there is at least one entry in it.<p>
938 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
940 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
941 <tt>Function</tt> or a null pointer if one has not been allocated (because there
942 are no named values in the function).<p>
944 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
946 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
947 <tt>Function</tt> or allocate a new <a
948 href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
949 should only be used when adding elements to the <a
950 href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
951 not left laying around.<p>
955 <!-- ======================================================================= -->
956 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
957 <tr><td> </td><td width="100%">
958 <font color="#EEEEFF" face="Georgia,Palatino"><b>
959 <a name="GlobalVariable">The <tt>GlobalVariable</tt> class</a>
960 </b></font></td></tr></table><ul>
963 href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt></b><br>
964 doxygen info: <a href="/doxygen/classGlobalVariable.html">GlobalVariable Class</a><br>
965 Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
966 href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a><p>
968 Global variables are represented with the (suprise suprise)
969 <tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are
970 also subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such
971 are always referenced by their address (global values must live in memory, so
972 their "name" refers to their address). Global variables may have an initial
973 value (which must be a <a href="#Constant"><tt>Constant</tt></a>), and if they
974 have an initializer, they may be marked as "constant" themselves (indicating
975 that their contents never change at runtime).<p>
978 <!-- _______________________________________________________________________ -->
979 </ul><h4><a name="m_GlobalVariable"><hr size=0>Important Public Members of the
980 <tt>GlobalVariable</tt> class</h4><ul>
982 <li><tt>GlobalVariable(const <a href="#Type">Type</a> *Ty, bool isConstant, bool
983 isInternal, <a href="#Constant">Constant</a> *Initializer = 0, const std::string
984 &Name = "")</tt><p>
986 Create a new global variable of the specified type. If <tt>isConstant</tt> is
987 true then the global variable will be marked as unchanging for the program, and
988 if <tt>isInternal</tt> is true the resultant global variable will have internal
989 linkage. Optionally an initializer and name may be specified for the global variable as well.<p>
992 <li><tt>bool isConstant() const</tt><p>
994 Returns true if this is a global variable is known not to be modified at
998 <li><tt>bool hasInitializer()</tt><p>
1000 Returns true if this <tt>GlobalVariable</tt> has an intializer.<p>
1003 <li><tt><a href="#Constant">Constant</a> *getInitializer()</tt><p>
1005 Returns the intial value for a <tt>GlobalVariable</tt>. It is not legal to call
1006 this method if there is no initializer.<p>
1009 <!-- ======================================================================= -->
1010 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1011 <tr><td> </td><td width="100%">
1012 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1013 <a name="Module">The <tt>Module</tt> class</a>
1014 </b></font></td></tr></table><ul>
1017 href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt></b><br>
1018 doxygen info: <a href="/doxygen/classModule.html">Module Class</a><p>
1020 The <tt>Module</tt> class represents the top level structure present in LLVM
1021 programs. An LLVM module is effectively either a translation unit of the
1022 original program or a combination of several translation units merged by the
1023 linker. The <tt>Module</tt> class keeps track of a list of <a
1024 href="#Function"><tt>Function</tt></a>s, a list of <a
1025 href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
1026 href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
1027 helpful member functions that try to make common operations easy.<p>
1030 <!-- _______________________________________________________________________ -->
1031 </ul><h4><a name="m_Module"><hr size=0>Important Public Members of the
1032 <tt>Module</tt> class</h4><ul>
1034 <li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
1035 <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
1036 <tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
1037 <tt>size()</tt>, <tt>empty()</tt>, <tt>rbegin()</tt>, <tt>rend()</tt><p>
1039 These are forwarding methods that make it easy to access the contents of a
1040 <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
1043 <li><tt>Module::FunctionListType &getFunctionList()</tt><p>
1045 Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
1046 neccesary to use when you need to update the list or perform a complex action
1047 that doesn't have a forwarding method.<p>
1049 <!-- Global Variable -->
1052 <li><tt>Module::giterator</tt> - Typedef for global variable list iterator<br>
1053 <tt>Module::const_giterator</tt> - Typedef for const_iterator.<br>
1054 <tt>gbegin()</tt>, <tt>gend()</tt>, <tt>gfront()</tt>, <tt>gback()</tt>,
1055 <tt>gsize()</tt>, <tt>gempty()</tt>, <tt>grbegin()</tt>, <tt>grend()</tt><p>
1057 These are forwarding methods that make it easy to access the contents of a
1058 <tt>Module</tt> object's <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>
1061 <li><tt>Module::GlobalListType &getGlobalList()</tt><p>
1063 Returns the list of <a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s.
1064 This is neccesary to use when you need to update the list or perform a complex
1065 action that doesn't have a forwarding method.<p>
1068 <!-- Symbol table stuff -->
1071 <li><tt>bool hasSymbolTable() const</tt><p>
1073 Return true if the <tt>Module</tt> has a symbol table allocated to it and if
1074 there is at least one entry in it.<p>
1076 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt><p>
1078 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1079 <tt>Module</tt> or a null pointer if one has not been allocated (because there
1080 are no named values in the function).<p>
1082 <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTableSure()</tt><p>
1084 Return a pointer to the <a href="#SymbolTable"><tt>SymbolTable</tt></a> for this
1085 <tt>Module</tt> or allocate a new <a
1086 href="#SymbolTable"><tt>SymbolTable</tt></a> if one is not already around. This
1087 should only be used when adding elements to the <a
1088 href="#SymbolTable"><tt>SymbolTable</tt></a>, so that empty symbol tables are
1089 not left laying around.<p>
1092 <!-- Convenience methods -->
1095 <li><tt><a href="#Function">Function</a> *getFunction(const std::string &Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt><p>
1097 Look up the specified function in the <tt>Module</tt> <a
1098 href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
1102 <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const std::string
1103 &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt><p>
1105 Look up the specified function in the <tt>Module</tt> <a
1106 href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
1107 external declaration for the function and return it.<p>
1110 <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt><p>
1112 If there is at least one entry in the <a
1113 href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
1114 href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
1118 <li><tt>bool addTypeName(const std::string &Name, const <a href="#Type">Type</a>
1121 Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a> mapping
1122 <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this name, true
1123 is returned and the <a href="#SymbolTable"><tt>SymbolTable</tt></a> is not
1127 <!-- ======================================================================= -->
1128 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1129 <tr><td> </td><td width="100%">
1130 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1131 <a name="Constant">The <tt>Constant</tt> class and subclasses</a>
1132 </b></font></td></tr></table><ul>
1134 Constant represents a base class for different types of constants. It is
1135 subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
1136 ConstantArray etc for representing the various types of Constants.<p>
1139 <!-- _______________________________________________________________________ -->
1140 </ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1142 <li><tt>bool isConstantExpr()</tt>: Returns true if it is a ConstantExpr
1147 \subsection{Important Subclasses of Constant}
1149 <li>ConstantSInt : This subclass of Constant represents a signed integer constant.
1151 <li><tt>int64_t getValue () const</tt>: Returns the underlying value of this constant.
1153 <li>ConstantUInt : This class represents an unsigned integer.
1155 <li><tt>uint64_t getValue () const</tt>: Returns the underlying value of this constant.
1157 <li>ConstantFP : This class represents a floating point constant.
1159 <li><tt>double getValue () const</tt>: Returns the underlying value of this constant.
1161 <li>ConstantBool : This represents a boolean constant.
1163 <li><tt>bool getValue () const</tt>: Returns the underlying value of this constant.
1165 <li>ConstantArray : This represents a constant array.
1167 <li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1169 <li>ConstantStruct : This represents a constant struct.
1171 <li><tt>const std::vector<Use> &getValues() const</tt>: Returns a Vecotr of component constants that makeup this array.
1173 <li>ConstantPointerRef : This represents a constant pointer value that is initialized to point to a global value, which lies at a constant fixed address.
1175 <li><tt>GlobalValue *getValue()</tt>: Returns the global value to which this pointer is pointing to.
1180 <!-- ======================================================================= -->
1181 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1182 <tr><td> </td><td width="100%">
1183 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1184 <a name="Type">The <tt>Type</tt> class and Derived Types</a>
1185 </b></font></td></tr></table><ul>
1187 Type as noted earlier is also a subclass of a Value class. Any primitive
1188 type (like int, short etc) in LLVM is an instance of Type Class. All
1189 other types are instances of subclasses of type like FunctionType,
1190 ArrayType etc. DerivedType is the interface for all such dervied types
1191 including FunctionType, ArrayType, PointerType, StructType. Types can have
1192 names. They can be recursive (StructType). There exists exactly one instance
1193 of any type structure at a time. This allows using pointer equality of Type *s for comparing types.
1195 <!-- _______________________________________________________________________ -->
1196 </ul><h4><a name="m_Value"><hr size=0>Important Public Methods</h4><ul>
1198 <li><tt>PrimitiveID getPrimitiveID () const</tt>: Returns the base type of the type.
1199 <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.
1200 <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.
1201 <li><tt> bool isInteger () const</tt>: Equilivent to isSigned() || isUnsigned(), but with only a single virtual function invocation.
1202 <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.
1204 <li><tt>bool isFloatingPoint ()</tt>: Return true if this is one of the two floating point types.
1205 <li><tt>bool isRecursive () const</tt>: Returns rue if the type graph contains a cycle.
1206 <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.
1207 <li><tt>bool isPrimitiveType () const</tt>: Returns true if it is a primitive type.
1208 <li><tt>bool isDerivedType () const</tt>: Returns true if it is a derived type.
1209 <li><tt>const Type * getContainedType (unsigned i) const</tt>:
1210 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.
1211 <li><tt>unsigned getNumContainedTypes () const</tt>: Return the number of types in the derived type.
1215 \subsection{Derived Types}
1217 <li>SequentialType : This is subclassed by ArrayType and PointerType
1219 <li><tt>const Type * getElementType () const</tt>: Returns the type of each of the elements in the sequential type.
1221 <li>ArrayType : This is a subclass of SequentialType and defines interface for array types.
1223 <li><tt>unsigned getNumElements () const</tt>: Returns the number of elements in the array.
1225 <li>PointerType : Subclass of SequentialType for pointer types.
1226 <li>StructType : subclass of DerivedTypes for struct types
1227 <li>FunctionType : subclass of DerivedTypes for function types.
1230 <li><tt>bool isVarArg () const</tt>: Returns true if its a vararg function
1231 <li><tt> const Type * getReturnType () const</tt>: Returns the return type of the function.
1232 <li><tt> const ParamTypes &getParamTypes () const</tt>: Returns a vector of parameter types.
1233 <li><tt>const Type * getParamType (unsigned i)</tt>: Returns the type of the ith parameter.
1234 <li><tt> const unsigned getNumParams () const</tt>: Returns the number of formal parameters.
1241 <!-- ======================================================================= -->
1242 </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1243 <tr><td> </td><td width="100%">
1244 <font color="#EEEEFF" face="Georgia,Palatino"><b>
1245 <a name="Argument">The <tt>Argument</tt> class</a>
1246 </b></font></td></tr></table><ul>
1248 This subclass of Value defines the interface for incoming formal arguments to a
1249 function. A Function maitanis a list of its formal arguments. An argument has a
1250 pointer to the parent Function.
1255 <!-- *********************************************************************** -->
1257 <!-- *********************************************************************** -->
1260 <address>By: <a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
1261 <a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1262 <!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
1263 <!-- hhmts start -->
1264 Last modified: Mon Sep 9 00:48:53 CDT 2002
1266 </font></body></html>