<ul>
<li><a href="#isa">The <tt>isa<></tt>, <tt>cast<></tt>
and <tt>dyn_cast<></tt> templates</a> </li>
- <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt>
+ <li><a href="#DEBUG">The <tt>DEBUG()</tt> macro and <tt>-debug</tt>
option</a>
<ul>
<li><a href="#DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt>
and the <tt>-debug-only</tt> option</a> </li>
</ul>
</li>
- <li><a href="#Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt>
+ <li><a href="#Statistic">The <tt>Statistic</tt> class & <tt>-stats</tt>
option</a></li>
<!--
<li>The <tt>InstVisitor</tt> template
<li>The general graph API
-->
+ <li><a href="#ViewGraph">Viewing graphs while debugging code</a></li>
</ul>
</li>
<li><a href="#common">Helpful Hints for Common Operations</a>
<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
<ul>
+ <li><a href="#Type">The <tt>Type</tt> class</a> </li>
<li><a href="#Value">The <tt>Value</tt> class</a>
<ul>
<li><a href="#User">The <tt>User</tt> class</a>
</li>
</ul>
</li>
- <li><a href="#Type">The <tt>Type</tt> class</a> </li>
<li><a href="#Argument">The <tt>Argument</tt> class</a></li>
</ul>
</li>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="isa">The isa<>, cast<> and dyn_cast<> templates</a>
+ <a name="isa">The <tt>isa<></tt>, <tt>cast<></tt> and
+ <tt>dyn_cast<></tt> templates</a>
</div>
<div class="doc_text">
<dl>
<dt><tt>isa<></tt>: </dt>
- <dd>The <tt>isa<></tt> operator works exactly like the Java
+ <dd><p>The <tt>isa<></tt> operator works exactly like the Java
"<tt>instanceof</tt>" operator. It returns true or false depending on whether
a reference or pointer points to an instance of the specified class. This can
- be very useful for constraint checking of various sorts (example below).</dd>
+ be very useful for constraint checking of various sorts (example below).</p>
+ </dd>
<dt><tt>cast<></tt>: </dt>
- <dd>The <tt>cast<></tt> operator is a "checked cast" operation. It
+ <dd><p>The <tt>cast<></tt> operator is a "checked cast" operation. It
converts a pointer or reference from a base class to a derived cast, causing
an assertion failure if it is not really an instance of the right type. This
should be used in cases where you have some information that makes you believe
that something is of the right type. An example of the <tt>isa<></tt>
- and <tt>cast<></tt> template is:
+ and <tt>cast<></tt> template is:</p>
- <pre>
- static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const Loop *L) {
- if (isa<<a href="#Constant">Constant</a>>(V) || isa<<a href="#Argument">Argument</a>>(V) || isa<<a href="#GlobalValue">GlobalValue</a>>(V))
- return true;
+<div class="doc_code">
+<pre>
+static bool isLoopInvariant(const <a href="#Value">Value</a> *V, const Loop *L) {
+ if (isa<<a href="#Constant">Constant</a>>(V) || isa<<a href="#Argument">Argument</a>>(V) || isa<<a href="#GlobalValue">GlobalValue</a>>(V))
+ return true;
- <i>// Otherwise, it must be an instruction...</i>
- return !L->contains(cast<<a href="#Instruction">Instruction</a>>(V)->getParent());
- }
- </pre>
+ // <i>Otherwise, it must be an instruction...</i>
+ return !L->contains(cast<<a href="#Instruction">Instruction</a>>(V)->getParent());
+}
+</pre>
+</div>
<p>Note that you should <b>not</b> use an <tt>isa<></tt> test followed
by a <tt>cast<></tt>, for that use the <tt>dyn_cast<></tt>
<dt><tt>dyn_cast<></tt>:</dt>
- <dd>The <tt>dyn_cast<></tt> operator is a "checking cast" operation. It
- checks to see if the operand is of the specified type, and if so, returns a
+ <dd><p>The <tt>dyn_cast<></tt> operator is a "checking cast" operation.
+ It checks to see if the operand is of the specified type, and if so, returns a
pointer to it (this operator does not work with references). If the operand is
not of the correct type, a null pointer is returned. Thus, this works very
- much like the <tt>dynamic_cast</tt> operator in C++, and should be used in the
- same circumstances. Typically, the <tt>dyn_cast<></tt> operator is used
- in an <tt>if</tt> statement or some other flow control statement like this:
-
- <pre>
- if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a href="#AllocationInst">AllocationInst</a>>(Val)) {
- ...
- }
- </pre>
+ much like the <tt>dynamic_cast<></tt> operator in C++, and should be
+ used in the same circumstances. Typically, the <tt>dyn_cast<></tt>
+ operator is used in an <tt>if</tt> statement or some other flow control
+ statement like this:</p>
+
+<div class="doc_code">
+<pre>
+if (<a href="#AllocationInst">AllocationInst</a> *AI = dyn_cast<<a href="#AllocationInst">AllocationInst</a>>(Val)) {
+ // <i>...</i>
+}
+</pre>
+</div>
- <p> This form of the <tt>if</tt> statement effectively combines together a
- call to <tt>isa<></tt> and a call to <tt>cast<></tt> into one
- statement, which is very convenient.</p>
+ <p>This form of the <tt>if</tt> statement effectively combines together a call
+ to <tt>isa<></tt> and a call to <tt>cast<></tt> into one
+ statement, which is very convenient.</p>
-
<p>Note that the <tt>dyn_cast<></tt> operator, like C++'s
- <tt>dynamic_cast</tt> or Java's <tt>instanceof</tt> operator, can be abused.
- In particular you should not use big chained <tt>if/then/else</tt> blocks to
- check for lots of different variants of classes. If you find yourself
- wanting to do this, it is much cleaner and more efficient to use the
- <tt>InstVisitor</tt> class to dispatch over the instruction type directly.</p>
+ <p>Note that the <tt>dyn_cast<></tt> operator, like C++'s
+ <tt>dynamic_cast<></tt> or Java's <tt>instanceof</tt> operator, can be
+ abused. In particular, you should not use big chained <tt>if/then/else</tt>
+ blocks to check for lots of different variants of classes. If you find
+ yourself wanting to do this, it is much cleaner and more efficient to use the
+ <tt>InstVisitor</tt> class to dispatch over the instruction type directly.</p>
- </dd>
+ </dd>
- <dt><tt>cast_or_null<></tt>: </dt>
-
- <dd>The <tt>cast_or_null<></tt> operator works just like the
- <tt>cast<></tt> operator, except that it allows for a null pointer as
- an argument (which it then propagates). This can sometimes be useful,
- allowing you to combine several null checks into one.</dd>
+ <dt><tt>cast_or_null<></tt>: </dt>
+
+ <dd><p>The <tt>cast_or_null<></tt> operator works just like the
+ <tt>cast<></tt> operator, except that it allows for a null pointer as an
+ argument (which it then propagates). This can sometimes be useful, allowing
+ you to combine several null checks into one.</p></dd>
- <dt><tt>dyn_cast_or_null<></tt>: </dt>
+ <dt><tt>dyn_cast_or_null<></tt>: </dt>
- <dd>The <tt>dyn_cast_or_null<></tt> operator works just like the
- <tt>dyn_cast<></tt> operator, except that it allows for a null pointer
- as an argument (which it then propagates). This can sometimes be useful,
- allowing you to combine several null checks into one.</dd>
+ <dd><p>The <tt>dyn_cast_or_null<></tt> operator works just like the
+ <tt>dyn_cast<></tt> operator, except that it allows for a null pointer
+ as an argument (which it then propagates). This can sometimes be useful,
+ allowing you to combine several null checks into one.</p></dd>
- </dl>
+</dl>
<p>These five templates can be used with any classes, whether they have a
v-table or not. To add support for these templates, you simply need to add
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="DEBUG">The <tt>DEBUG()</tt> macro & <tt>-debug</tt> option</a>
+ <a name="DEBUG">The <tt>DEBUG()</tt> macro and <tt>-debug</tt> option</a>
</div>
<div class="doc_text">
<p>Often when working on your pass you will put a bunch of debugging printouts
and other code into your pass. After you get it working, you want to remove
-it... but you may need it again in the future (to work out new bugs that you run
+it, but you may need it again in the future (to work out new bugs that you run
across).</p>
<p> Naturally, because of this, you don't want to delete the debug printouts,
<tt>DEBUG</tt> macro, and it is only executed if '<tt>opt</tt>' (or any other
tool) is run with the '<tt>-debug</tt>' command line argument:</p>
- <pre> ... <br> DEBUG(std::cerr << "I am here!\n");<br> ...<br></pre>
+<div class="doc_code">
+<pre>
+DOUT << "I am here!\n";
+</pre>
+</div>
<p>Then you can run your pass like this:</p>
- <pre> $ opt < a.bc > /dev/null -mypass<br> <no output><br> $ opt < a.bc > /dev/null -mypass -debug<br> I am here!<br> $<br></pre>
+<div class="doc_code">
+<pre>
+$ opt < a.bc > /dev/null -mypass
+<i><no output></i>
+$ opt < a.bc > /dev/null -mypass -debug
+I am here!
+</pre>
+</div>
<p>Using the <tt>DEBUG()</tt> macro instead of a home-brewed solution allows you
to not have to create "yet another" command line option for the debug output for
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE()</tt> and
+ <a name="DEBUG_TYPE">Fine grained debug info with <tt>DEBUG_TYPE</tt> and
the <tt>-debug-only</tt> option</a>
</div>
control, you define the <tt>DEBUG_TYPE</tt> macro and the <tt>-debug</tt> only
option as follows:</p>
- <pre> ...<br> DEBUG(std::cerr << "No debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE "foo"<br> DEBUG(std::cerr << "'foo' debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE "bar"<br> DEBUG(std::cerr << "'bar' debug type\n");<br> #undef DEBUG_TYPE<br> #define DEBUG_TYPE ""<br> DEBUG(std::cerr << "No debug type (2)\n");<br> ...<br></pre>
+<div class="doc_code">
+<pre>
+DOUT << "No debug type\n";
+#undef DEBUG_TYPE
+#define DEBUG_TYPE "foo"
+DOUT << "'foo' debug type\n";
+#undef DEBUG_TYPE
+#define DEBUG_TYPE "bar"
+DOUT << "'bar' debug type\n";
+#undef DEBUG_TYPE
+#define DEBUG_TYPE ""
+DOUT << "No debug type (2)\n";
+</pre>
+</div>
<p>Then you can run your pass like this:</p>
- <pre> $ opt < a.bc > /dev/null -mypass<br> <no output><br> $ opt < a.bc > /dev/null -mypass -debug<br> No debug type<br> 'foo' debug type<br> 'bar' debug type<br> No debug type (2)<br> $ opt < a.bc > /dev/null -mypass -debug-only=foo<br> 'foo' debug type<br> $ opt < a.bc > /dev/null -mypass -debug-only=bar<br> 'bar' debug type<br> $<br></pre>
+<div class="doc_code">
+<pre>
+$ opt < a.bc > /dev/null -mypass
+<i><no output></i>
+$ opt < a.bc > /dev/null -mypass -debug
+No debug type
+'foo' debug type
+'bar' debug type
+No debug type (2)
+$ opt < a.bc > /dev/null -mypass -debug-only=foo
+'foo' debug type
+$ opt < a.bc > /dev/null -mypass -debug-only=bar
+'bar' debug type
+</pre>
+</div>
<p>Of course, in practice, you should only set <tt>DEBUG_TYPE</tt> at the top of
a file, to specify the debug type for the entire module (if you do this before
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="Statistic">The <tt>Statistic</tt> template & <tt>-stats</tt>
+ <a name="Statistic">The <tt>Statistic</tt> class & <tt>-stats</tt>
option</a>
</div>
<p>The "<tt><a
href="/doxygen/Statistic_8h-source.html">llvm/ADT/Statistic.h</a></tt>" file
-provides a template named <tt>Statistic</tt> that is used as a unified way to
+provides a class named <tt>Statistic</tt> that is used as a unified way to
keep track of what the LLVM compiler is doing and how effective various
optimizations are. It is useful to see what optimizations are contributing to
making a particular program run faster.</p>
<p>Often you may run your pass on some big program, and you're interested to see
how many times it makes a certain transformation. Although you can do this with
hand inspection, or some ad-hoc method, this is a real pain and not very useful
-for big programs. Using the <tt>Statistic</tt> template makes it very easy to
+for big programs. Using the <tt>Statistic</tt> class makes it very easy to
keep track of this information, and the calculated information is presented in a
uniform manner with the rest of the passes being executed.</p>
it are as follows:</p>
<ol>
- <li>Define your statistic like this:
- <pre>static Statistic<> NumXForms("mypassname", "The # of times I did stuff");<br></pre>
+ <li><p>Define your statistic like this:</p>
- <p>The <tt>Statistic</tt> template can emulate just about any data-type,
- but if you do not specify a template argument, it defaults to acting like
- an unsigned int counter (this is usually what you want).</p></li>
+<div class="doc_code">
+<pre>
+#define <a href="#DEBUG_TYPE">DEBUG_TYPE</a> "mypassname" <i>// This goes before any #includes.</i>
+STATISTIC(NumXForms, "The # of times I did stuff");
+</pre>
+</div>
+
+ <p>The <tt>STATISTIC</tt> macro defines a static variable, whose name is
+ specified by the first argument. The pass name is taken from the DEBUG_TYPE
+ macro, and the description is taken from the second argument. The variable
+ defined ("NumXForms" in this case) acts like an unsigned integer.</p></li>
+
+ <li><p>Whenever you make a transformation, bump the counter:</p>
+
+<div class="doc_code">
+<pre>
+++NumXForms; // <i>I did stuff!</i>
+</pre>
+</div>
- <li>Whenever you make a transformation, bump the counter:
- <pre> ++NumXForms; // I did stuff<br></pre>
</li>
</ol>
<p>That's all you have to do. To get '<tt>opt</tt>' to print out the
statistics gathered, use the '<tt>-stats</tt>' option:</p>
- <pre> $ opt -stats -mypassname < program.bc > /dev/null<br> ... statistic output ...<br></pre>
+<div class="doc_code">
+<pre>
+$ opt -stats -mypassname < program.bc > /dev/null
+<i>... statistics output ...</i>
+</pre>
+</div>
<p> When running <tt>gccas</tt> on a C file from the SPEC benchmark
suite, it gives a report that looks like this:</p>
- <pre> 7646 bytecodewriter - Number of normal instructions<br> 725 bytecodewriter - Number of oversized instructions<br> 129996 bytecodewriter - Number of bytecode bytes written<br> 2817 raise - Number of insts DCEd or constprop'd<br> 3213 raise - Number of cast-of-self removed<br> 5046 raise - Number of expression trees converted<br> 75 raise - Number of other getelementptr's formed<br> 138 raise - Number of load/store peepholes<br> 42 deadtypeelim - Number of unused typenames removed from symtab<br> 392 funcresolve - Number of varargs functions resolved<br> 27 globaldce - Number of global variables removed<br> 2 adce - Number of basic blocks removed<br> 134 cee - Number of branches revectored<br> 49 cee - Number of setcc instruction eliminated<br> 532 gcse - Number of loads removed<br> 2919 gcse - Number of instructions removed<br> 86 indvars - Number of canonical indvars added<br> 87 indvars - Number of aux indvars removed<br> 25 instcombine - Number of dead inst eliminate<br> 434 instcombine - Number of insts combined<br> 248 licm - Number of load insts hoisted<br> 1298 licm - Number of insts hoisted to a loop pre-header<br> 3 licm - Number of insts hoisted to multiple loop preds (bad, no loop pre-header)<br> 75 mem2reg - Number of alloca's promoted<br> 1444 cfgsimplify - Number of blocks simplified<br></pre>
+<div class="doc_code">
+<pre>
+ 7646 bytecodewriter - Number of normal instructions
+ 725 bytecodewriter - Number of oversized instructions
+ 129996 bytecodewriter - Number of bytecode bytes written
+ 2817 raise - Number of insts DCEd or constprop'd
+ 3213 raise - Number of cast-of-self removed
+ 5046 raise - Number of expression trees converted
+ 75 raise - Number of other getelementptr's formed
+ 138 raise - Number of load/store peepholes
+ 42 deadtypeelim - Number of unused typenames removed from symtab
+ 392 funcresolve - Number of varargs functions resolved
+ 27 globaldce - Number of global variables removed
+ 2 adce - Number of basic blocks removed
+ 134 cee - Number of branches revectored
+ 49 cee - Number of setcc instruction eliminated
+ 532 gcse - Number of loads removed
+ 2919 gcse - Number of instructions removed
+ 86 indvars - Number of canonical indvars added
+ 87 indvars - Number of aux indvars removed
+ 25 instcombine - Number of dead inst eliminate
+ 434 instcombine - Number of insts combined
+ 248 licm - Number of load insts hoisted
+ 1298 licm - Number of insts hoisted to a loop pre-header
+ 3 licm - Number of insts hoisted to multiple loop preds (bad, no loop pre-header)
+ 75 mem2reg - Number of alloca's promoted
+ 1444 cfgsimplify - Number of blocks simplified
+</pre>
+</div>
<p>Obviously, with so many optimizations, having a unified framework for this
stuff is very nice. Making your pass fit well into the framework makes it more
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ViewGraph">Viewing graphs while debugging code</a>
+</div>
+
+<div class="doc_text">
+
+<p>Several of the important data structures in LLVM are graphs: for example
+CFGs made out of LLVM <a href="#BasicBlock">BasicBlock</a>s, CFGs made out of
+LLVM <a href="CodeGenerator.html#machinebasicblock">MachineBasicBlock</a>s, and
+<a href="CodeGenerator.html#selectiondag_intro">Instruction Selection
+DAGs</a>. In many cases, while debugging various parts of the compiler, it is
+nice to instantly visualize these graphs.</p>
+
+<p>LLVM provides several callbacks that are available in a debug build to do
+exactly that. If you call the <tt>Function::viewCFG()</tt> method, for example,
+the current LLVM tool will pop up a window containing the CFG for the function
+where each basic block is a node in the graph, and each node contains the
+instructions in the block. Similarly, there also exists
+<tt>Function::viewCFGOnly()</tt> (does not include the instructions), the
+<tt>MachineFunction::viewCFG()</tt> and <tt>MachineFunction::viewCFGOnly()</tt>,
+and the <tt>SelectionDAG::viewGraph()</tt> methods. Within GDB, for example,
+you can usually use something like <tt>call DAG.viewGraph()</tt> to pop
+up a window. Alternatively, you can sprinkle calls to these functions in your
+code in places you want to debug.</p>
+
+<p>Getting this to work requires a small amount of configuration. On Unix
+systems with X11, install the <a href="http://www.graphviz.org">graphviz</a>
+toolkit, and make sure 'dot' and 'gv' are in your path. If you are running on
+Mac OS/X, download and install the Mac OS/X <a
+href="http://www.pixelglow.com/graphviz/">Graphviz program</a>, and add
+<tt>/Applications/Graphviz.app/Contents/MacOS/</tt> (or whereever you install
+it) to your path. Once in your system and path are set up, rerun the LLVM
+configure script and rebuild LLVM to enable this functionality.</p>
+
+<p><tt>SelectionDAG</tt> has been extended to make it easier to locate
+<i>interesting</i> nodes in large complex graphs. From gdb, if you
+<tt>call DAG.setGraphColor(<i>node</i>, "<i>color</i>")</tt>, then the
+next <tt>call DAG.viewGraph()</tt> would hilight the node in the
+specified color (choices of colors can be found at <a
+href="http://www.graphviz.org/doc/info/colors.html">Colors<a>.) More
+complex node attributes can be provided with <tt>call
+DAG.setGraphAttrs(<i>node</i>, "<i>attributes</i>")</tt> (choices can be
+found at <a href="http://www.graphviz.org/doc/info/attrs.html">Graph
+Attributes</a>.) If you want to restart and clear all the current graph
+attributes, then you can <tt>call DAG.clearGraphAttrs()</tt>. </p>
+
+</div>
+
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="common">Helpful Hints for Common Operations</a>
an example that prints the name of a <tt>BasicBlock</tt> and the number of
<tt>Instruction</tt>s it contains:</p>
- <pre> // func is a pointer to a Function instance<br> for (Function::iterator i = func->begin(), e = func->end(); i != e; ++i) {<br><br> // print out the name of the basic block if it has one, and then the<br> // number of instructions that it contains<br><br> cerr << "Basic block (name=" << i->getName() << ") has " <br> << i->size() << " instructions.\n";<br> }<br></pre>
+<div class="doc_code">
+<pre>
+// <i>func is a pointer to a Function instance</i>
+for (Function::iterator i = func->begin(), e = func->end(); i != e; ++i)
+ // <i>Print out the name of the basic block if it has one, and then the</i>
+ // <i>number of instructions that it contains</i>
+ llvm::cerr << "Basic block (name=" << i->getName() << ") has "
+ << i->size() << " instructions.\n";
+</pre>
+</div>
<p>Note that i can be used as if it were a pointer for the purposes of
invoking member functions of the <tt>Instruction</tt> class. This is
<tt>BasicBlock</tt>s. Here's a code snippet that prints out each instruction in
a <tt>BasicBlock</tt>:</p>
+<div class="doc_code">
<pre>
- // blk is a pointer to a BasicBlock instance
- for (BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)
- // the next statement works since operator<<(ostream&,...)
- // is overloaded for Instruction&
- std::cerr << *i << "\n";
+// <i>blk is a pointer to a BasicBlock instance</i>
+for (BasicBlock::iterator i = blk->begin(), e = blk->end(); i != e; ++i)
+ // <i>The next statement works since operator<<(ostream&,...)</i>
+ // <i>is overloaded for Instruction&</i>
+ llvm::cerr << *i << "\n";
</pre>
+</div>
<p>However, this isn't really the best way to print out the contents of a
<tt>BasicBlock</tt>! Since the ostream operators are overloaded for virtually
anything you'll care about, you could have just invoked the print routine on the
-basic block itself: <tt>std::cerr << *blk << "\n";</tt>.</p>
+basic block itself: <tt>llvm::cerr << *blk << "\n";</tt>.</p>
</div>
and then instantiate <tt>InstIterator</tt>s explicitly in your code. Here's a
small example that shows how to dump all instructions in a function to the standard error stream:<p>
- <pre>#include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"<br>...<br>// Suppose F is a ptr to a function<br>for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)<br> cerr << *i << "\n";<br></pre>
-Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
+<div class="doc_code">
+<pre>
+#include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"
+
+// <i>F is a ptr to a Function instance</i>
+for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
+ llvm::cerr << *i << "\n";
+</pre>
+</div>
+
+<p>Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
worklist with its initial contents. For example, if you wanted to
initialize a worklist to contain all instructions in a <tt>Function</tt>
-F, all you would need to do is something like:
- <pre>std::set<Instruction*> worklist;<br>worklist.insert(inst_begin(F), inst_end(F));<br></pre>
+F, all you would need to do is something like:</p>
+
+<div class="doc_code">
+<pre>
+std::set<Instruction*> worklist;
+worklist.insert(inst_begin(F), inst_end(F));
+</pre>
+</div>
<p>The STL set <tt>worklist</tt> would now contain all instructions in the
<tt>Function</tt> pointed to by F.</p>
Assuming that <tt>i</tt> is a <tt>BasicBlock::iterator</tt> and <tt>j</tt>
is a <tt>BasicBlock::const_iterator</tt>:</p>
- <pre> Instruction& inst = *i; // grab reference to instruction reference<br> Instruction* pinst = &*i; // grab pointer to instruction reference<br> const Instruction& inst = *j;<br></pre>
+<div class="doc_code">
+<pre>
+Instruction& inst = *i; // <i>Grab reference to instruction reference</i>
+Instruction* pinst = &*i; // <i>Grab pointer to instruction reference</i>
+const Instruction& inst = *j;
+</pre>
+</div>
<p>However, the iterators you'll be working with in the LLVM framework are
special: they will automatically convert to a ptr-to-instance type whenever they
(behind the scenes, this is a result of overloading casting mechanisms). Thus
the last line of the last example,</p>
- <pre>Instruction* pinst = &*i;</pre>
+<div class="doc_code">
+<pre>
+Instruction* pinst = &*i;
+</pre>
+</div>
<p>is semantically equivalent to</p>
- <pre>Instruction* pinst = i;</pre>
+<div class="doc_code">
+<pre>
+Instruction* pinst = i;
+</pre>
+</div>
<p>It's also possible to turn a class pointer into the corresponding iterator,
and this is a constant time operation (very efficient). The following code
iterators. By using these, you can explicitly grab the iterator of something
without actually obtaining it via iteration over some structure:</p>
- <pre>void printNextInstruction(Instruction* inst) {<br> BasicBlock::iterator it(inst);<br> ++it; // after this line, it refers to the instruction after *inst.<br> if (it != inst->getParent()->end()) cerr << *it << "\n";<br>}<br></pre>
+<div class="doc_code">
+<pre>
+void printNextInstruction(Instruction* inst) {
+ BasicBlock::iterator it(inst);
+ ++it; // <i>After this line, it refers to the instruction after *inst</i>
+ if (it != inst->getParent()->end()) llvm::cerr << *it << "\n";
+}
+</pre>
+</div>
</div>
you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this
is what we want to do:</p>
- <pre>initialize callCounter to zero<br>for each Function f in the Module<br> for each BasicBlock b in f<br> for each Instruction i in b<br> if (i is a CallInst and calls the given function)<br> increment callCounter<br></pre>
+<div class="doc_code">
+<pre>
+initialize callCounter to zero
+for each Function f in the Module
+ for each BasicBlock b in f
+ for each Instruction i in b
+ if (i is a CallInst and calls the given function)
+ increment callCounter
+</pre>
+</div>
-<p>And the actual code is (remember, since we're writing a
+<p>And the actual code is (remember, because we're writing a
<tt>FunctionPass</tt>, our <tt>FunctionPass</tt>-derived class simply has to
-override the <tt>runOnFunction</tt> method...):</p>
+override the <tt>runOnFunction</tt> method):</p>
- <pre>Function* targetFunc = ...;<br><br>class OurFunctionPass : public FunctionPass {<br> public:<br> OurFunctionPass(): callCounter(0) { }<br><br> virtual runOnFunction(Function& F) {<br> for (Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {<br> for (BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {<br> if (<a
- href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a
- href="#CallInst">CallInst</a>>(&*i)) {<br> // we know we've encountered a call instruction, so we<br> // need to determine if it's a call to the<br> // function pointed to by m_func or not.<br> <br> if (callInst->getCalledFunction() == targetFunc)<br> ++callCounter;<br> }<br> }<br> }<br> <br> private:<br> unsigned callCounter;<br>};<br></pre>
+<div class="doc_code">
+<pre>
+Function* targetFunc = ...;
+
+class OurFunctionPass : public FunctionPass {
+ public:
+ OurFunctionPass(): callCounter(0) { }
+
+ virtual runOnFunction(Function& F) {
+ for (Function::iterator b = F.begin(), be = F.end(); b != be; ++b) {
+ for (BasicBlock::iterator i = b->begin(); ie = b->end(); i != ie; ++i) {
+ if (<a href="#CallInst">CallInst</a>* callInst = <a href="#isa">dyn_cast</a><<a
+ href="#CallInst">CallInst</a>>(&*i)) {
+ // <i>We know we've encountered a call instruction, so we</i>
+ // <i>need to determine if it's a call to the</i>
+ // <i>function pointed to by m_func or not</i>
+
+ if (callInst->getCalledFunction() == targetFunc)
+ ++callCounter;
+ }
+ }
+ }
+ }
+
+ private:
+ unsigned callCounter;
+};
+</pre>
+</div>
</div>
most-specific common base class is <tt>Instruction</tt>, which includes lots of
less closely-related things. For these cases, LLVM provides a handy wrapper
class called <a
-href="http://llvm.cs.uiuc.edu/doxygen/classllvm_1_1CallSite.html"><tt>CallSite</tt></a>.
+href="http://llvm.org/doxygen/classllvm_1_1CallSite.html"><tt>CallSite</tt></a>.
It is essentially a wrapper around an <tt>Instruction</tt> pointer, with some
methods that provide functionality common to <tt>CallInst</tt>s and
<tt>InvokeInst</tt>s.</p>
<div class="doc_text">
<p>Frequently, we might have an instance of the <a
-href="/doxygen/structllvm_1_1Value.html">Value Class</a> and we want to
+href="/doxygen/classllvm_1_1Value.html">Value Class</a> and we want to
determine which <tt>User</tt>s use the <tt>Value</tt>. The list of all
<tt>User</tt>s of a particular <tt>Value</tt> is called a <i>def-use</i> chain.
For example, let's say we have a <tt>Function*</tt> named <tt>F</tt> to a
<i>use</i> <tt>foo</tt> is as simple as iterating over the <i>def-use</i> chain
of <tt>F</tt>:</p>
- <pre>Function* F = ...;<br><br>for (Value::use_iterator i = F->use_begin(), e = F->use_end(); i != e; ++i) {<br> if (Instruction *Inst = dyn_cast<Instruction>(*i)) {<br> cerr << "F is used in instruction:\n";<br> cerr << *Inst << "\n";<br> }<br>}<br></pre>
+<div class="doc_code">
+<pre>
+Function* F = ...;
+
+for (Value::use_iterator i = F->use_begin(), e = F->use_end(); i != e; ++i)
+ if (Instruction *Inst = dyn_cast<Instruction>(*i)) {
+ llvm::cerr << "F is used in instruction:\n";
+ llvm::cerr << *Inst << "\n";
+ }
+</pre>
+</div>
<p>Alternately, it's common to have an instance of the <a
href="/doxygen/classllvm_1_1User.html">User Class</a> and need to know what
all of the values that a particular instruction uses (that is, the operands of
the particular <tt>Instruction</tt>):</p>
- <pre>Instruction* pi = ...;<br><br>for (User::op_iterator i = pi->op_begin(), e = pi->op_end(); i != e; ++i) {<br> Value* v = *i;<br> ...<br>}<br></pre>
+<div class="doc_code">
+<pre>
+Instruction* pi = ...;
+
+for (User::op_iterator i = pi->op_begin(), e = pi->op_end(); i != e; ++i) {
+ Value* v = *i;
+ // <i>...</i>
+}
+</pre>
+</div>
<!--
def-use chains ("finding all users of"): Value::use_begin/use_end
parameters. For example, an <tt>AllocaInst</tt> only <i>requires</i> a
(const-ptr-to) <tt>Type</tt>. Thus:</p>
-<pre>AllocaInst* ai = new AllocaInst(Type::IntTy);</pre>
+<div class="doc_code">
+<pre>
+AllocaInst* ai = new AllocaInst(Type::IntTy);
+</pre>
+</div>
<p>will create an <tt>AllocaInst</tt> instance that represents the allocation of
one integer in the current stack frame, at runtime. Each <tt>Instruction</tt>
<tt>Function</tt>, and I'm intending to use it within the same
<tt>Function</tt>. I might do:</p>
- <pre>AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");</pre>
+<div class="doc_code">
+<pre>
+AllocaInst* pa = new AllocaInst(Type::IntTy, 0, "indexLoc");
+</pre>
+</div>
<p>where <tt>indexLoc</tt> is now the logical name of the instruction's
execution value, which is a pointer to an integer on the runtime stack.</p>
<tt>BasicBlock</tt>, and a newly-created instruction we wish to insert
before <tt>*pi</tt>, we do the following: </p>
- <pre> BasicBlock *pb = ...;<br> Instruction *pi = ...;<br> Instruction *newInst = new Instruction(...);<br> pb->getInstList().insert(pi, newInst); // inserts newInst before pi in pb<br></pre>
+<div class="doc_code">
+<pre>
+BasicBlock *pb = ...;
+Instruction *pi = ...;
+Instruction *newInst = new Instruction(...);
+
+pb->getInstList().insert(pi, newInst); // <i>Inserts newInst before pi in pb</i>
+</pre>
+</div>
<p>Appending to the end of a <tt>BasicBlock</tt> is so common that
the <tt>Instruction</tt> class and <tt>Instruction</tt>-derived
<tt>BasicBlock</tt> to be appended to. For example code that
looked like: </p>
- <pre> BasicBlock *pb = ...;<br> Instruction *newInst = new Instruction(...);<br> pb->getInstList().push_back(newInst); // appends newInst to pb<br></pre>
+<div class="doc_code">
+<pre>
+BasicBlock *pb = ...;
+Instruction *newInst = new Instruction(...);
+
+pb->getInstList().push_back(newInst); // <i>Appends newInst to pb</i>
+</pre>
+</div>
<p>becomes: </p>
- <pre> BasicBlock *pb = ...;<br> Instruction *newInst = new Instruction(..., pb);<br></pre>
+<div class="doc_code">
+<pre>
+BasicBlock *pb = ...;
+Instruction *newInst = new Instruction(..., pb);
+</pre>
+</div>
<p>which is much cleaner, especially if you are creating
long instruction streams.</p></li>
thing as the above code without being given a <tt>BasicBlock</tt> by doing:
</p>
- <pre> Instruction *pi = ...;<br> Instruction *newInst = new Instruction(...);<br> pi->getParent()->getInstList().insert(pi, newInst);<br></pre>
+<div class="doc_code">
+<pre>
+Instruction *pi = ...;
+Instruction *newInst = new Instruction(...);
+
+pi->getParent()->getInstList().insert(pi, newInst);
+</pre>
+</div>
<p>In fact, this sequence of steps occurs so frequently that the
<tt>Instruction</tt> class and <tt>Instruction</tt>-derived classes provide
<tt>Instruction</tt> constructor with a <tt>insertBefore</tt> (default)
parameter, the above code becomes:</p>
- <pre>Instruction* pi = ...;<br>Instruction* newInst = new Instruction(..., pi);<br></pre>
+<div class="doc_code">
+<pre>
+Instruction* pi = ...;
+Instruction* newInst = new Instruction(..., pi);
+</pre>
+</div>
<p>which is much cleaner, especially if you're creating a lot of
-instructions and adding them to <tt>BasicBlock</tt>s.</p></li>
+ instructions and adding them to <tt>BasicBlock</tt>s.</p></li>
</ul>
</div>
pointer to the basic block to get its list of instructions and then use the
erase function to remove your instruction. For example:</p>
- <pre> <a href="#Instruction">Instruction</a> *I = .. ;<br> <a
- href="#BasicBlock">BasicBlock</a> *BB = I->getParent();<br> BB->getInstList().erase(I);<br></pre>
+<div class="doc_code">
+<pre>
+<a href="#Instruction">Instruction</a> *I = .. ;
+<a href="#BasicBlock">BasicBlock</a> *BB = I->getParent();
+
+BB->getInstList().erase(I);
+</pre>
+</div>
</div>
<tt>AllocaInst</tt> that allocates memory for a single integer with a null
pointer to an integer.</p>
- <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,<br> Constant::getNullValue(PointerType::get(Type::IntTy)));<br></pre></li>
+<div class="doc_code">
+<pre>
+AllocaInst* instToReplace = ...;
+BasicBlock::iterator ii(instToReplace);
+
+ReplaceInstWithValue(instToReplace->getParent()->getInstList(), ii,
+ Constant::getNullValue(PointerType::get(Type::IntTy)));
+</pre></div></li>
<li><tt>ReplaceInstWithInst</tt>
instruction. The following example illustrates the replacement of one
<tt>AllocaInst</tt> with another.</p>
- <pre>AllocaInst* instToReplace = ...;<br>BasicBlock::iterator ii(instToReplace);<br>ReplaceInstWithInst(instToReplace->getParent()->getInstList(), ii,<br> new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt"));<br></pre></li>
+<div class="doc_code">
+<pre>
+AllocaInst* instToReplace = ...;
+BasicBlock::iterator ii(instToReplace);
+
+ReplaceInstWithInst(instToReplace->getParent()->getInstList(), ii,
+ new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt"));
+</pre></div></li>
</ul>
<p><i>Replacing multiple uses of <tt>User</tt>s and <tt>Value</tt>s</i></p>
<p>You can use <tt>Value::replaceAllUsesWith</tt> and
<tt>User::replaceUsesOfWith</tt> to change more than one use at a time. See the
-doxygen documentation for the <a href="/doxygen/structllvm_1_1Value.html">Value Class</a>
+doxygen documentation for the <a href="/doxygen/classllvm_1_1Value.html">Value Class</a>
and <a href="/doxygen/classllvm_1_1User.html">User Class</a>, respectively, for more
information.</p>
For our purposes below, we need three concepts. First, an "Opaque Type" is
exactly as defined in the <a href="LangRef.html#t_opaque">language
reference</a>. Second an "Abstract Type" is any type which includes an
-opaque type as part of its type graph (for example "<tt>{ opaque, int }</tt>").
-Third, a concrete type is a type that is not an abstract type (e.g. "<tt>[ int,
+opaque type as part of its type graph (for example "<tt>{ opaque, i32 }</tt>").
+Third, a concrete type is a type that is not an abstract type (e.g. "<tt>{ i32,
float }</tt>").
</p>
to be emitted to an output .ll file:
</p>
+<div class="doc_code">
<pre>
- %mylist = type { %mylist*, int }
+%mylist = type { %mylist*, i32 }
</pre>
+</div>
<p>
To build this, use the following LLVM APIs:
</p>
+<div class="doc_code">
<pre>
- //<i> Create the initial outer struct.</i>
-
<a href="#PATypeHolder">PATypeHolder</a> StructTy = OpaqueType::get();
- std::vector<const Type*> Elts;
- Elts.push_back(PointerType::get(StructTy));
- Elts.push_back(Type::IntTy);
- StructType *NewSTy = StructType::get(Elts);
-
- //<i> At this point, NewSTy = "{ opaque*, int }". Tell VMCore that</i>
- //<i> the struct and the opaque type are actually the same.</i>
-
cast<OpaqueType>(StructTy.get())-><a href="#refineAbstractTypeTo">refineAbstractTypeTo</a>(NewSTy);
-
-
// <i>NewSTy is potentially invalidated, but StructTy (a <a href="#PATypeHolder">PATypeHolder</a>) is</i>
- // <i>kept up-to-date.</i>
- NewSTy = cast<StructType>(StructTy.get());
-
- // <i>Add a name for the type to the module symbol table (optional).</i>
- MyModule->addTypeName("mylist", NewSTy);
+// <i>Create the initial outer struct</i>
+<a href="#PATypeHolder">PATypeHolder</a> StructTy = OpaqueType::get();
+std::vector<const Type*> Elts;
+Elts.push_back(PointerType::get(StructTy));
+Elts.push_back(Type::IntTy);
+StructType *NewSTy = StructType::get(Elts);
+
+// <i>At this point, NewSTy = "{ opaque*, i32 }". Tell VMCore that</i>
+// <i>the struct and the opaque type are actually the same.</i>
+cast<OpaqueType>(StructTy.get())-><a href="#refineAbstractTypeTo">refineAbstractTypeTo</a>(NewSTy);
+
+// <i>NewSTy is potentially invalidated, but StructTy (a <a href="#PATypeHolder">PATypeHolder</a>) is</i>
+// <i>kept up-to-date</i>
+NewSTy = cast<StructType>(StructTy.get());
+
+// <i>Add a name for the type to the module symbol table (optional)</i>
+MyModule->addTypeName("mylist", NewSTy);
</pre>
+</div>
<p>
This code shows the basic approach used to build recursive types: build a
<p>
In the example above, the OpaqueType object is definitely deleted.
-Additionally, if there is an "{ \2*, int}" type already created in the system,
+Additionally, if there is an "{ \2*, i32}" type already created in the system,
the pointer and struct type created are <b>also</b> deleted. Obviously whenever
a type is deleted, any "Type*" pointers in the program are invalidated. As
such, it is safest to avoid having <i>any</i> "Type*" pointers to abstract types
allows it to get callbacks when certain types are resolved. To register to get
callbacks for a particular type, the DerivedType::{add/remove}AbstractTypeUser
methods can be called on a type. Note that these methods only work for <i>
-abstract</i> types. Concrete types (those that do not include an opaque objects
-somewhere) can never be refined.
+ abstract</i> types. Concrete types (those that do not include any opaque
+objects) can never be refined.
</p>
</div>
<p>This class provides a symbol table that the <a
href="#Function"><tt>Function</tt></a> and <a href="#Module">
<tt>Module</tt></a> classes use for naming definitions. The symbol table can
-provide a name for any <a href="#Value"><tt>Value</tt></a> or <a
-href="#Type"><tt>Type</tt></a>. <tt>SymbolTable</tt> is an abstract data
-type. It hides the data it contains and provides access to it through a
-controlled interface.</p>
-
-<p>Note that the symbol table class is should not be directly accessed by most
-clients. It should only be used when iteration over the symbol table names
-themselves are required, which is very special purpose. Note that not all LLVM
+provide a name for any <a href="#Value"><tt>Value</tt></a>.
+<tt>SymbolTable</tt> is an abstract data type. It hides the data it contains
+and provides access to it through a controlled interface.</p>
+
+<p>Note that the <tt>SymbolTable</tt> class should not be directly accessed
+by most clients. It should only be used when iteration over the symbol table
+names themselves are required, which is very special purpose. Note that not
+all LLVM
<a href="#Value">Value</a>s have names, and those without names (i.e. they have
an empty name) do not exist in the symbol table.
</p>
structure of the information it holds. The class contains two
<tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of
<tt>Type*</tt> to maps of name (<tt>std::string</tt>) to <tt>Value*</tt>.
-The second, <tt>tmap</tt>, is a map of names to <tt>Type*</tt>. Thus, Values
-are stored in two-dimensions and accessed by <tt>Type</tt> and name. Types,
-however, are stored in a single dimension and accessed only by name.</p>
+Thus, Values are stored in two-dimensions and accessed by <tt>Type</tt> and
+name.</p>
<p>The interface of this class provides three basic types of operations:
<ol>
<a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>
<li><em>Iterators</em>. Iterators allow the user to traverse the content
of the symbol table in well defined ways, such as the method
- <a href="#SymbolTable_type_begin"><tt>type_begin</tt></a>.</li>
+ <a href="#SymbolTable_plane_begin"><tt>plane_begin</tt></a>.</li>
</ol>
<h3>Accessors</h3>
<tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.
If a suitable <tt>Value</tt> is not found, null is returned.</dd>
- <dt><tt>Type* lookupType( const std::string& name) const</tt>:</dt>
- <dd>The <tt>lookupType</tt> method searches through the types for a
- <tt>Type</tt> with the provided <tt>name</tt>. If a suitable <tt>Type</tt>
- is not found, null is returned.</dd>
-
- <dt><tt>bool hasTypes() const</tt>:</dt>
- <dd>This function returns true if an entry has been made into the type
- map.</dd>
-
<dt><tt>bool isEmpty() const</tt>:</dt>
<dd>This function returns true if both the value and types maps are
empty</dd>
name. There can be a many to one mapping between names and constants
or types.</dd>
- <dt><tt>void insert(const std::string& Name, Type *Typ)</tt>:</dt>
- <dd> Inserts a type into the symbol table with the specified name. There
- can be a many-to-one mapping between names and types. This method
- allows a type with an existing entry in the symbol table to get
- a new name.</dd>
-
<dt><tt>void remove(Value* Val)</tt>:</dt>
<dd> This method removes a named value from the symbol table. The
type and name of the Value are extracted from \p N and used to
not in the symbol table, this method silently ignores the
request.</dd>
- <dt><tt>void remove(Type* Typ)</tt>:</dt>
- <dd> This method removes a named type from the symbol table. The
- name of the type is extracted from \P T and used to look up
- the Type in the type map. If the Type is not in the symbol
- table, this method silently ignores the request.</dd>
-
<dt><tt>Value* remove(const std::string& Name, Value *Val)</tt>:</dt>
<dd> Remove a constant or type with the specified name from the
symbol table.</dd>
- <dt><tt>Type* remove(const std::string& Name, Type* T)</tt>:</dt>
- <dd> Remove a type with the specified name from the symbol table.
- Returns the removed Type.</dd>
-
- <dt><tt>Value *value_remove(const value_iterator& It)</tt>:</dt>
+ <dt><tt>Value *remove(const value_iterator& It)</tt>:</dt>
<dd> Removes a specific value from the symbol table.
Returns the removed value.</dd>
the beginning or end of the sequence for both const and non-const. It is
important to keep track of the different kinds of iterators. There are
three idioms worth pointing out:</p>
+
<table>
<tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>
<tr>
<td align="left"><pre><tt>
for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),
PE = ST.plane_end(); PI != PE; ++PI ) {
- PI->first // This is the Type* of the plane
- PI->second // This is the SymbolTable::ValueMap of name/Value pairs
- </tt></pre></td>
- </tr>
- <tr>
- <td align="left">All name/Type Pairs</td><td>TI</td>
- <td align="left"><pre><tt>
-for (SymbolTable::type_const_iterator TI = ST.type_begin(),
- TE = ST.type_end(); TI != TE; ++TI )
- TI->first // This is the name of the type
- TI->second // This is the Type* value associated with the name
+ PI->first // <i>This is the Type* of the plane</i>
+ PI->second // <i>This is the SymbolTable::ValueMap of name/Value pairs</i>
+}
</tt></pre></td>
</tr>
<tr>
<td align="left">name/Value pairs in a plane</td><td>VI</td>
<td align="left"><pre><tt>
for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),
- VE = ST.value_end(SomeType); VI != VE; ++VI )
- VI->first // This is the name of the Value
- VI->second // This is the Value* value associated with the name
+ VE = ST.value_end(SomeType); VI != VE; ++VI ) {
+ VI->first // <i>This is the name of the Value</i>
+ VI->second // <i>This is the Value* value associated with the name</i>
+}
</tt></pre></td>
</tr>
</table>
marker for end of iteration of the type plane.
Note: the type plane must already exist before using this.</dd>
- <dt><tt>type_iterator type_begin()</tt>:</dt>
- <dd>Get an iterator to the start of the name/Type map.</dd>
-
- <dt><tt>type_const_iterator type_begin() cons</tt>:</dt>
- <dd> Get a const_iterator to the start of the name/Type map.</dd>
-
- <dt><tt>type_iterator type_end()</tt>:</dt>
- <dd>Get an iterator to the end of the name/Type map. This serves as the
- marker for end of iteration of the types.</dd>
-
- <dt><tt>type_const_iterator type_end() const</tt>:</dt>
- <dd>Get a const-iterator to the end of the name/Type map. This serves
- as the marker for end of iteration of the types.</dd>
-
<dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>
<dd>This method returns a plane_const_iterator for iteration over
the type planes starting at a specific plane, given by \p Ty.</dd>
<!-- *********************************************************************** -->
<div class="doc_text">
+<p><tt>#include "<a href="/doxygen/Type_8h-source.html">llvm/Type.h</a>"</tt>
+<br>doxygen info: <a href="/doxygen/classllvm_1_1Type.html">Type Class</a></p>
<p>The Core LLVM classes are the primary means of representing the program
being inspected or transformed. The core LLVM classes are defined in
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="Type">The <tt>Type</tt> class and Derived Types</a>
+</div>
+
+<div class="doc_text">
+
+ <p><tt>Type</tt> is a superclass of all type classes. Every <tt>Value</tt> has
+ a <tt>Type</tt>. <tt>Type</tt> cannot be instantiated directly but only
+ through its subclasses. Certain primitive types (<tt>VoidType</tt>,
+ <tt>LabelType</tt>, <tt>FloatType</tt> and <tt>DoubleType</tt>) have hidden
+ subclasses. They are hidden because they offer no useful functionality beyond
+ what the <tt>Type</tt> class offers except to distinguish themselves from
+ other subclasses of <tt>Type</tt>.</p>
+ <p>All other types are subclasses of <tt>DerivedType</tt>. Types can be
+ named, but this is not a requirement. There exists exactly
+ one instance of a given shape at any one time. This allows type equality to
+ be performed with address equality of the Type Instance. That is, given two
+ <tt>Type*</tt> values, the types are identical if the pointers are identical.
+ </p>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="m_Value">Important Public Methods</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+ <li><tt>bool isInteger() const</tt>: Returns true for any integer type.</li>
+
+ <li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two
+ floating point types.</li>
+
+ <li><tt>bool isAbstract()</tt>: Return true if the type is abstract (contains
+ an OpaqueType anywhere in its definition).</li>
+
+ <li><tt>bool isSized()</tt>: Return true if the type has known size. Things
+ that don't have a size are abstract types, labels and void.</li>
+
+</ul>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="m_Value">Important Derived Types</a>
+</div>
+<div class="doc_text">
+<dl>
+ <dt><tt>IntegerType</tt></dt>
+ <dd>Subclass of DerivedType that represents integer types of any bit width.
+ Any bit width between <tt>IntegerType::MIN_INT_BITS</tt> (1) and
+ <tt>IntegerType::MAX_INT_BITS</tt> (~8 million) can be represented.
+ <ul>
+ <li><tt>static const IntegerType* get(unsigned NumBits)</tt>: get an integer
+ type of a specific bit width.</li>
+ <li><tt>unsigned getBitWidth() const</tt>: Get the bit width of an integer
+ type.</li>
+ </ul>
+ </dd>
+ <dt><tt>SequentialType</tt></dt>
+ <dd>This is subclassed by ArrayType and PointerType
+ <ul>
+ <li><tt>const Type * getElementType() const</tt>: Returns the type of each
+ of the elements in the sequential type. </li>
+ </ul>
+ </dd>
+ <dt><tt>ArrayType</tt></dt>
+ <dd>This is a subclass of SequentialType and defines the interface for array
+ types.
+ <ul>
+ <li><tt>unsigned getNumElements() const</tt>: Returns the number of
+ elements in the array. </li>
+ </ul>
+ </dd>
+ <dt><tt>PointerType</tt></dt>
+ <dd>Subclass of SequentialType for pointer types.</li>
+ <dt><tt>PackedType</tt></dt>
+ <dd>Subclass of SequentialType for packed (vector) types. A
+ packed type is similar to an ArrayType but is distinguished because it is
+ a first class type wherease ArrayType is not. Packed types are used for
+ vector operations and are usually small vectors of of an integer or floating
+ point type.</dd>
+ <dt><tt>StructType</tt></dt>
+ <dd>Subclass of DerivedTypes for struct types.</dd>
+ <dt><tt>FunctionType</tt></dt>
+ <dd>Subclass of DerivedTypes for function types.
+ <ul>
+ <li><tt>bool isVarArg() const</tt>: Returns true if its a vararg
+ function</li>
+ <li><tt> const Type * getReturnType() const</tt>: Returns the
+ return type of the function.</li>
+ <li><tt>const Type * getParamType (unsigned i)</tt>: Returns
+ the type of the ith parameter.</li>
+ <li><tt> const unsigned getNumParams() const</tt>: Returns the
+ number of formal parameters.</li>
+ </ul>
+ </dd>
+ <dt><tt>OpaqueType</tt></dt>
+ <dd>Sublcass of DerivedType for abstract types. This class
+ defines no content and is used as a placeholder for some other type. Note
+ that OpaqueType is used (temporarily) during type resolution for forward
+ references of types. Once the referenced type is resolved, the OpaqueType
+ is replaced with the actual type. OpaqueType can also be used for data
+ abstraction. At link time opaque types can be resolved to actual types
+ of the same name.</dd>
+</dl>
+</div>
+
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="Value">The <tt>Value</tt> class</a>
<p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>
<br>
-doxygen info: <a href="/doxygen/structllvm_1_1Value.html">Value Class</a></p>
+doxygen info: <a href="/doxygen/classllvm_1_1Value.html">Value Class</a></p>
<p>The <tt>Value</tt> class is the most important class in the LLVM Source
base. It represents a typed value that may be used (among other things) as an
method. In addition, all LLVM values can be named. The "name" of the
<tt>Value</tt> is a symbolic string printed in the LLVM code:</p>
- <pre> %<b>foo</b> = add int 1, 2<br></pre>
+<div class="doc_code">
+<pre>
+%<b>foo</b> = add i32 1, 2
+</pre>
+</div>
<p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>
that the name of any value may be missing (an empty string), so names should
produces a constant value (for example through constant folding), you can
replace all uses of the instruction with the constant like this:</p>
- <pre> Inst->replaceAllUsesWith(ConstVal);<br></pre>
+<div class="doc_code">
+<pre>
+Inst->replaceAllUsesWith(ConstVal);
+</pre>
+</div>
+
</ul>
</div>
the <tt>Instruction</tt> class is the <tt>llvm/Instruction.def</tt> file. This
file contains some meta-data about the various different types of instructions
in LLVM. It describes the enum values that are used as opcodes (for example
-<tt>Instruction::Add</tt> and <tt>Instruction::SetLE</tt>), as well as the
+<tt>Instruction::Add</tt> and <tt>Instruction::ICmp</tt>), as well as the
concrete sub-classes of <tt>Instruction</tt> that implement the instruction (for
example <tt><a href="#BinaryOperator">BinaryOperator</a></tt> and <tt><a
-href="#SetCondInst">SetCondInst</a></tt>). Unfortunately, the use of macros in
+href="#CmpInst">CmpInst</a></tt>). Unfortunately, the use of macros in
this file confuses doxygen, so these enum values don't show up correctly in the
<a href="/doxygen/classllvm_1_1Instruction.html">doxygen output</a>.</p>
</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="s_Instruction">Important Subclasses of the <tt>Instruction</tt>
+ class</a>
+</div>
+<div class="doc_text">
+ <ul>
+ <li><tt><a name="BinaryOperator">BinaryOperator</a></tt>
+ <p>This subclasses represents all two operand instructions whose operands
+ must be the same type, except for the comparison instructions.</p></li>
+ <li><tt><a name="CastInst">CastInst</a></tt>
+ <p>This subclass is the parent of the 12 casting instructions. It provides
+ common operations on cast instructions.</p>
+ <li><tt><a name="CmpInst">CmpInst</a></tt>
+ <p>This subclass respresents the two comparison instructions,
+ <a href="LangRef.html#i_icmp">ICmpInst</a> (integer opreands), and
+ <a href="LangRef.html#i_fcmp">FCmpInst</a> (floating point operands).</p>
+ <li><tt><a name="TerminatorInst">TerminatorInst</a></tt>
+ <p>This subclass is the parent of all terminator instructions (those which
+ can terminate a block).</p>
+ </ul>
+ </div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="m_Instruction">Important Public Members of the <tt>Instruction</tt>
href="/doxygen/GlobalValue_8h-source.html">llvm/GlobalValue.h</a>"</tt><br>
doxygen info: <a href="/doxygen/classllvm_1_1GlobalValue.html">GlobalValue
Class</a><br>
-Superclasses: <a href="#User"><tt>User</tt></a>, <a
-href="#Value"><tt>Value</tt></a></p>
+Superclasses: <a href="#Constant"><tt>Constant</tt></a>,
+<a href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
<p>Global values (<a href="#GlobalVariable"><tt>GlobalVariable</tt></a>s or <a
href="#Function"><tt>Function</tt></a>s) are the only LLVM values that are
when using the <tt>GetElementPtrInst</tt> instruction because this pointer must
be dereferenced first. For example, if you have a <tt>GlobalVariable</tt> (a
subclass of <tt>GlobalValue)</tt> that is an array of 24 ints, type <tt>[24 x
-int]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although
+i32]</tt>, then the <tt>GlobalVariable</tt> is a pointer to that array. Although
the address of the first element of this array and the value of the
<tt>GlobalVariable</tt> are the same, they have different types. The
-<tt>GlobalVariable</tt>'s type is <tt>[24 x int]</tt>. The first element's type
-is <tt>int.</tt> Because of this, accessing a global value requires you to
+<tt>GlobalVariable</tt>'s type is <tt>[24 x i32]</tt>. The first element's type
+is <tt>i32.</tt> Because of this, accessing a global value requires you to
dereference the pointer with <tt>GetElementPtrInst</tt> first, then its elements
can be accessed. This is explained in the <a href="LangRef.html#globalvars">LLVM
Language Reference Manual</a>.</p>
<p><tt>#include "<a
href="/doxygen/Function_8h-source.html">llvm/Function.h</a>"</tt><br> doxygen
info: <a href="/doxygen/classllvm_1_1Function.html">Function Class</a><br>
-Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
-href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
+Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>,
+<a href="#Constant"><tt>Constant</tt></a>,
+<a href="#User"><tt>User</tt></a>,
+<a href="#Value"><tt>Value</tt></a></p>
<p>The <tt>Function</tt> class represents a single procedure in LLVM. It is
actually one of the more complex classes in the LLVM heirarchy because it must
keep track of a large amount of data. The <tt>Function</tt> class keeps track
-of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal <a
-href="#Argument"><tt>Argument</tt></a>s, and a <a
-href="#SymbolTable"><tt>SymbolTable</tt></a>.</p>
+of a list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s, a list of formal
+<a href="#Argument"><tt>Argument</tt></a>s, and a
+<a href="#SymbolTable"><tt>SymbolTable</tt></a>.</p>
<p>The list of <a href="#BasicBlock"><tt>BasicBlock</tt></a>s is the most
commonly used part of <tt>Function</tt> objects. The list imposes an implicit
href="/doxygen/GlobalVariable_8h-source.html">llvm/GlobalVariable.h</a>"</tt>
<br>
doxygen info: <a href="/doxygen/classllvm_1_1GlobalVariable.html">GlobalVariable
-Class</a><br> Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>, <a
-href="#User"><tt>User</tt></a>, <a href="#Value"><tt>Value</tt></a></p>
+ Class</a><br>
+Superclasses: <a href="#GlobalValue"><tt>GlobalValue</tt></a>,
+<a href="#Constant"><tt>Constant</tt></a>,
+<a href="#User"><tt>User</tt></a>,
+<a href="#Value"><tt>Value</tt></a></p>
<p>Global variables are represented with the (suprise suprise)
<tt>GlobalVariable</tt> class. Like functions, <tt>GlobalVariable</tt>s are also
subclasses of <a href="#GlobalValue"><tt>GlobalValue</tt></a>, and as such are
always referenced by their address (global values must live in memory, so their
-"name" refers to their address). See <a
-href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global variables
-may have an initial value (which must be a <a
-href="#Constant"><tt>Constant</tt></a>), and if they have an initializer, they
-may be marked as "constant" themselves (indicating that their contents never
-change at runtime).</p>
-
+"name" refers to their constant address). See
+<a href="#GlobalValue"><tt>GlobalValue</tt></a> for more on this. Global
+variables may have an initial value (which must be a
+<a href="#Constant"><tt>Constant</tt></a>), and if they have an initializer,
+they may be marked as "constant" themselves (indicating that their contents
+never change at runtime).</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_text">
<p>Constant represents a base class for different types of constants. It
-is subclassed by ConstantBool, ConstantInt, ConstantSInt, ConstantUInt,
-ConstantArray etc for representing the various types of Constants.</p>
+is subclassed by ConstantInt, ConstantArray, etc. for representing
+the various types of Constants.</p>
</div>
<div class="doc_subsubsection">Important Subclasses of Constant </div>
<div class="doc_text">
<ul>
- <li>ConstantSInt : This subclass of Constant represents a signed integer
- constant.
+ <li>ConstantInt : This subclass of Constant represents an integer constant of
+ any width, including boolean (1 bit integer).
<ul>
- <li><tt>int64_t getValue() const</tt>: Returns the underlying value of
- this constant. </li>
- </ul>
- </li>
- <li>ConstantUInt : This class represents an unsigned integer.
- <ul>
- <li><tt>uint64_t getValue() const</tt>: Returns the underlying value of
- this constant. </li>
+ <li><tt>int64_t getSExtValue() const</tt>: Returns the underlying value of
+ this constant as a sign extended signed integer value.</li>
+ <li><tt>uint64_t getZExtValue() const</tt>: Returns the underlying value
+ of this constant as a zero extended unsigned integer value.</li>
+ <li><tt>static ConstantInt* get(const Type *Ty, uint64_t Val)</tt>:
+ Returns the ConstantInt object that represents the value provided by
+ <tt>Val</tt> for integer type <tt>Ty</tt>.</li>
</ul>
</li>
<li>ConstantFP : This class represents a floating point constant.
this constant. </li>
</ul>
</li>
- <li>ConstantBool : This represents a boolean constant.
<ul>
<li><tt>bool getValue() const</tt>: Returns the underlying value of this
constant. </li>
</li>
</ul>
</div>
-
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="Type">The <tt>Type</tt> class and Derived Types</a>
-</div>
-
-<div class="doc_text">
-
-<p>Type as noted earlier is also a subclass of a Value class. Any primitive
-type (like int, short etc) in LLVM is an instance of Type Class. All other
-types are instances of subclasses of type like FunctionType, ArrayType
-etc. DerivedType is the interface for all such dervied types including
-FunctionType, ArrayType, PointerType, StructType. Types can have names. They can
-be recursive (StructType). There exists exactly one instance of any type
-structure at a time. This allows using pointer equality of Type *s for comparing
-types.</p>
-
-</div>
-
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="m_Value">Important Public Methods</a>
-</div>
-
-<div class="doc_text">
-
-<ul>
-
- <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. </li>
-
- <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. </li>
-
- <li><tt>bool isInteger() const</tt>: Equivalent to isSigned() || isUnsigned().</li>
-
- <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.</li>
-
- <li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two
- floating point types.</li>
-
- <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 or one pointer type to another.</li>
-</ul>
-</div>
-
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="m_Value">Important Derived Types</a>
-</div>
-<div class="doc_text">
-<ul>
- <li>SequentialType : This is subclassed by ArrayType and PointerType
- <ul>
- <li><tt>const Type * getElementType() const</tt>: Returns the type of each
- of the elements in the sequential type. </li>
- </ul>
- </li>
- <li>ArrayType : This is a subclass of SequentialType and defines interface for
- array types.
- <ul>
- <li><tt>unsigned getNumElements() const</tt>: Returns the number of
- elements in the array. </li>
- </ul>
- </li>
- <li>PointerType : Subclass of SequentialType for pointer types. </li>
- <li>StructType : subclass of DerivedTypes for struct types </li>
- <li>FunctionType : subclass of DerivedTypes for function types.
- <ul>
- <li><tt>bool isVarArg() const</tt>: Returns true if its a vararg
- function</li>
- <li><tt> const Type * getReturnType() const</tt>: Returns the
- return type of the function.</li>
- <li><tt>const Type * getParamType (unsigned i)</tt>: Returns
- the type of the ith parameter.</li>
- <li><tt> const unsigned getNumParams() const</tt>: Returns the
- number of formal parameters.</li>
- </ul>
- </li>
-</ul>
-</div>
-
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="Argument">The <tt>Argument</tt> class</a>
<a href="mailto:dhurjati@cs.uiuc.edu">Dinakar Dhurjati</a> and
<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
- <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
</address>
</body>
</html>
-<!-- vim: sw=2 noai
--->
projects / oota-llvm.git / blobdiff