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 <div class="doc_title"> LLVM Language Reference Manual </div>
 <ol>
   <li><a href="#abstract">Abstract</a></li>
   <li><a href="#introduction">Introduction</a></li>
   <li><a href="#identifiers">Identifiers</a></li>
   <li><a href="#typesystem">Type System</a>
     <ol>
       <li><a href="#t_primitive">Primitive Types</a>
         <ol>
           <li><a href="#t_classifications">Type Classifications</a></li>
         </ol>
       </li>
       <li><a href="#t_derived">Derived Types</a>
         <ol>
           <li><a href="#t_array">Array Type</a></li>
           <li><a href="#t_function">Function Type</a></li>
           <li><a href="#t_pointer">Pointer Type</a></li>
           <li><a href="#t_struct">Structure Type</a></li>
 <!-- <li><a href="#t_packed" >Packed Type</a> -->
         </ol>
       </li>
     </ol>
   </li>
   <li><a href="#highlevel">High Level Structure</a>
     <ol>
       <li><a href="#modulestructure">Module Structure</a></li>
       <li><a href="#globalvars">Global Variables</a></li>
       <li><a href="#functionstructure">Function Structure</a></li>
     </ol>
   </li>
   <li><a href="#instref">Instruction Reference</a>
     <ol>
       <li><a href="#terminators">Terminator Instructions</a>
         <ol>
           <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
           <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
           <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
           <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
           <li><a href="#i_unwind">'<tt>unwind</tt>'  Instruction</a></li>
         </ol>
       </li>
       <li><a href="#binaryops">Binary Operations</a>
         <ol>
           <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
           <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
           <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
           <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
           <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
           <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
         </ol>
       </li>
       <li><a href="#bitwiseops">Bitwise Binary Operations</a>
         <ol>
           <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
           <li><a href="#i_or">'<tt>or</tt>'  Instruction</a></li>
           <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
           <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
           <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
         </ol>
       </li>
       <li><a href="#memoryops">Memory Access Operations</a>
         <ol>
           <li><a href="#i_malloc">'<tt>malloc</tt>'   Instruction</a></li>
           <li><a href="#i_free">'<tt>free</tt>'     Instruction</a></li>
           <li><a href="#i_alloca">'<tt>alloca</tt>'   Instruction</a></li>
 	 <li><a href="#i_load">'<tt>load</tt>'     Instruction</a></li>
 	 <li><a href="#i_store">'<tt>store</tt>'    Instruction</a></li>
 	 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
         </ol>
       </li>
       <li><a href="#otherops">Other Operations</a>
         <ol>
           <li><a href="#i_phi">'<tt>phi</tt>'   Instruction</a></li>
           <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
           <li><a href="#i_call">'<tt>call</tt>'  Instruction</a></li>
           <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
           <li><a href="#i_vaarg">'<tt>vaarg</tt>'  Instruction</a></li>
         </ol>
       </li>
     </ol>
   </li>
   <li><a href="#intrinsics">Intrinsic Functions</a>
     <ol>
       <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
         <ol>
           <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
           <li><a href="#i_va_end">'<tt>llvm.va_end</tt>'   Intrinsic</a></li>
           <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>'  Intrinsic</a></li>
         </ol>
       </li>
       <li><a href="#int_libc">Standard C Library Intrinsics</a>
         <ol>
           <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
           <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
         </ol>
       </li>
       <li><a href="#int_debugger">Debugger intrinsics</a>
     </ol>
   </li>
 </ol>
 <div class="doc_text">
 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></b></p>
 <p> </p>
 </div>
 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="abstract">Abstract </a></div>
 <!-- *********************************************************************** -->
 <div class="doc_text">
 <p>This document is a reference manual for the LLVM assembly language.
 LLVM is an SSA based representation that provides type safety,
 low-level operations, flexibility, and the capability of representing
 'all' high-level languages cleanly.  It is the common code
 representation used throughout all phases of the LLVM compilation
 strategy.</p>
 </div>
 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="introduction">Introduction</a> </div>
 <!-- *********************************************************************** -->
 <div class="doc_text">
 <p>The LLVM code representation is designed to be used in three
 different forms: as an in-memory compiler IR, as an on-disk bytecode
 representation (suitable for fast loading by a Just-In-Time compiler),
 and as a human readable assembly language representation.  This allows
 LLVM to provide a powerful intermediate representation for efficient
 compiler transformations and analysis, while providing a natural means
 to debug and visualize the transformations.  The three different forms
 of LLVM are all equivalent.  This document describes the human readable
 representation and notation.</p>
 <p>The LLVM representation aims to be a light-weight and low-level
 while being expressive, typed, and extensible at the same time.  It
 aims to be a "universal IR" of sorts, by being at a low enough level
 that high-level ideas may be cleanly mapped to it (similar to how
 microprocessors are "universal IR's", allowing many source languages to
 be mapped to them).  By providing type information, LLVM can be used as
 the target of optimizations: for example, through pointer analysis, it
 can be proven that a C automatic variable is never accessed outside of
 the current function... allowing it to be promoted to a simple SSA
 value instead of a memory location.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
 <div class="doc_text">
 <p>It is important to note that this document describes 'well formed'
 LLVM assembly language.  There is a difference between what the parser
 accepts and what is considered 'well formed'.  For example, the
 following instruction is syntactically okay, but not well formed:</p>
 <pre>  %x = <a href="#i_add">add</a> int 1, %x<br></pre>
 <p>...because the definition of <tt>%x</tt> does not dominate all of
 its uses. The LLVM infrastructure provides a verification pass that may
 be used to verify that an LLVM module is well formed.  This pass is
 automatically run by the parser after parsing input assembly, and by
 the optimizer before it outputs bytecode.  The violations pointed out
 by the verifier pass indicate bugs in transformation passes or input to
 the parser.</p>
 <!-- Describe the typesetting conventions here. --> </div>
 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
 <!-- *********************************************************************** -->
 <div class="doc_text">
 <p>LLVM uses three different forms of identifiers, for different
 purposes:</p>
 <ol>
   <li>Numeric constants are represented as you would expect: 12, -3
 123.421,   etc.  Floating point constants have an optional hexidecimal
 notation.</li>
   <li>Named values are represented as a string of characters with a '%'
 prefix.   For example, %foo, %DivisionByZero,
 %a.really.long.identifier.  The actual   regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
 Identifiers which require other characters in their names can be
 surrounded   with quotes.  In this way, anything except a <tt>"</tt>
 character can be used   in a name.</li>
   <li>Unnamed values are represented as an unsigned numeric value with
 a '%'   prefix.  For example, %12, %2, %44.</li>
 </ol>
 <p>LLVM requires the values start with a '%' sign for two reasons:
 Compilers don't need to worry about name clashes with reserved words,
 and the set of reserved words may be expanded in the future without
 penalty.  Additionally, unnamed identifiers allow a compiler to quickly
 come up with a temporary variable without having to avoid symbol table
 conflicts.</p>
 <p>Reserved words in LLVM are very similar to reserved words in other
 languages. There are keywords for different opcodes ('<tt><a
  href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
  href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
  href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>',
 etc...), and others.  These reserved words cannot conflict with
 variable names, because none of them start with a '%' character.</p>
 <p>Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>'
 by 8:</p>
 <p>The easy way:</p>
 <pre>  %result = <a href="#i_mul">mul</a> uint %X, 8<br></pre>
 <p>After strength reduction:</p>
 <pre>  %result = <a href="#i_shl">shl</a> uint %X, ubyte 3<br></pre>
 <p>And the hard way:</p>
 <pre>  <a href="#i_add">add</a> uint %X, %X           <i>; yields {uint}:%0</i>
   <a
  href="#i_add">add</a> uint %0, %0           <i>; yields {uint}:%1</i>
   %result = <a
  href="#i_add">add</a> uint %1, %1<br></pre>
 <p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
 important lexical features of LLVM:</p>
 <ol>
   <li>Comments are delimited with a '<tt>;</tt>' and go until the end
 of   line.</li>
   <li>Unnamed temporaries are created when the result of a computation
 is not   assigned to a named value.</li>
   <li>Unnamed temporaries are numbered sequentially</li>
 </ol>
 <p>...and it also show a convention that we follow in this document.
 When demonstrating instructions, we will follow an instruction with a
 comment that defines the type and name of value produced.  Comments are
 shown in italic text.</p>
 <p>The one non-intuitive notation for constants is the optional
 hexidecimal form of floating point constants.  For example, the form '<tt>double
 0x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
 4.5e+15</tt>' which is also supported by the parser.  The only time
 hexadecimal floating point constants are useful (and the only time that
 they are generated by the disassembler) is when an FP constant has to
 be emitted that is not representable as a decimal floating point number
 exactly.  For example, NaN's, infinities, and other special cases are
 represented in their IEEE hexadecimal format so that assembly and
 disassembly do not cause any bits to change in the constants.</p>
 </div>
 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="typesystem">Type System</a> </div>
 <!-- *********************************************************************** -->
 <div class="doc_text">
 <p>The LLVM type system is one of the most important features of the
 intermediate representation.  Being typed enables a number of
 optimizations to be performed on the IR directly, without having to do
 extra analyses on the side before the transformation.  A strong type
 system makes it easier to read the generated code and enables novel
 analyses and transformations that are not feasible to perform on normal
 three address code representations.</p>
 <!-- The written form for the type system was heavily influenced by the
 syntactic problems with types in the C language<sup><a
 href="#rw_stroustrup">1</a></sup>.<p> --> </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
 <div class="doc_text">
 <p>The primitive types are the fundemental building blocks of the LLVM
 system. The current set of primitive types are as follows:</p>
 <p>
 <table border="0" align="center">
   <tbody>
     <tr>
       <td>
       <table border="1" cellspacing="0" cellpadding="4" align="center">
         <tbody>
           <tr>
             <td><tt>void</tt></td>
             <td>No value</td>
           </tr>
           <tr>
             <td><tt>ubyte</tt></td>
             <td>Unsigned 8 bit value</td>
           </tr>
           <tr>
             <td><tt>ushort</tt></td>
             <td>Unsigned 16 bit value</td>
           </tr>
           <tr>
             <td><tt>uint</tt></td>
             <td>Unsigned 32 bit value</td>
           </tr>
           <tr>
             <td><tt>ulong</tt></td>
             <td>Unsigned 64 bit value</td>
           </tr>
           <tr>
             <td><tt>float</tt></td>
             <td>32 bit floating point value</td>
           </tr>
           <tr>
             <td><tt>label</tt></td>
             <td>Branch destination</td>
           </tr>
         </tbody>
       </table>
       </td>
       <td valign="top">
       <table border="1" cellspacing="0" cellpadding="4" align="center&quot;">
         <tbody>
           <tr>
             <td><tt>bool</tt></td>
             <td>True or False value</td>
           </tr>
           <tr>
             <td><tt>sbyte</tt></td>
             <td>Signed 8 bit value</td>
           </tr>
           <tr>
             <td><tt>short</tt></td>
             <td>Signed 16 bit value</td>
           </tr>
           <tr>
             <td><tt>int</tt></td>
             <td>Signed 32 bit value</td>
           </tr>
           <tr>
             <td><tt>long</tt></td>
             <td>Signed 64 bit value</td>
           </tr>
           <tr>
             <td><tt>double</tt></td>
             <td>64 bit floating point value</td>
           </tr>
         </tbody>
       </table>
       </td>
     </tr>
   </tbody>
 </table>
 </p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="t_classifications">Type
 Classifications</a> </div>
 <div class="doc_text">
 <p>These different primitive types fall into a few useful
 classifications:</p>
 <p>
 <table border="1" cellspacing="0" cellpadding="4" align="center">
   <tbody>
     <tr>
       <td><a name="t_signed">signed</a></td>
       <td><tt>sbyte, short, int, long, float, double</tt></td>
     </tr>
     <tr>
       <td><a name="t_unsigned">unsigned</a></td>
       <td><tt>ubyte, ushort, uint, ulong</tt></td>
     </tr>
     <tr>
       <td><a name="t_integer">integer</a></td>
       <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
     </tr>
     <tr>
       <td><a name="t_integral">integral</a></td>
       <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
     </tr>
     <tr>
       <td><a name="t_floating">floating point</a></td>
       <td><tt>float, double</tt></td>
     </tr>
     <tr>
       <td><a name="t_firstclass">first class</a></td>
       <td><tt>bool, ubyte, sbyte, ushort, short,<br>
 uint, int, ulong, long, float, double, <a href="#t_pointer">pointer</a></tt></td>
     </tr>
   </tbody>
 </table>
 </p>
 <p>The <a href="#t_firstclass">first class</a> types are perhaps the
 most important.  Values of these types are the only ones which can be
 produced by instructions, passed as arguments, or used as operands to
 instructions.  This means that all structures and arrays must be
 manipulated either by pointer or by component.</p>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
 <div class="doc_text">
 <p>The real power in LLVM comes from the derived types in the system.
 This is what allows a programmer to represent arrays, functions,
 pointers, and other useful types.  Note that these derived types may be
 recursive: For example, it is possible to have a two dimensional array.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
 <div class="doc_text">
 <h5>Overview:</h5>
 <p>The array type is a very simple derived type that arranges elements
 sequentially in memory.  The array type requires a size (number of
 elements) and an underlying data type.</p>
 <h5>Syntax:</h5>
 <pre>  [&lt;# elements&gt; x &lt;elementtype&gt;]<br></pre>
 <p>The number of elements is a constant integer value, elementtype may
 be any type with a size.</p>
 <h5>Examples:</h5>
 <p> <tt>[40 x int ]</tt>: Array of 40 integer values.<br>
 <tt>[41 x int ]</tt>: Array of 41 integer values.<br>
 <tt>[40 x uint]</tt>: Array of 40 unsigned integer values.</p>
 <p> </p>
 <p>Here are some examples of multidimensional arrays:</p>
 <p>
 <table border="0" cellpadding="0" cellspacing="0">
   <tbody>
     <tr>
       <td><tt>[3 x [4 x int]]</tt></td>
       <td>: 3x4 array integer values.</td>
     </tr>
     <tr>
       <td><tt>[12 x [10 x float]]</tt></td>
       <td>: 12x10 array of single precision floating point values.</td>
     </tr>
     <tr>
       <td><tt>[2 x [3 x [4 x uint]]]</tt></td>
       <td>: 2x3x4 array of unsigned integer values.</td>
     </tr>
   </tbody>
 </table>
 </p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
 <div class="doc_text">
 <h5>Overview:</h5>
 <p>The function type can be thought of as a function signature.  It
 consists of a return type and a list of formal parameter types.
 Function types are usually used to build virtual function tables
 (which are structures of pointers to functions), for indirect function
 calls, and when defining a function.</p>
 <p>
 The return type of a function type cannot be an aggregate type.
 </p>
 <h5>Syntax:</h5>
 <pre>  &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
 <p>Where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of
 type specifiers.  Optionally, the parameter list may include a type <tt>...</tt>,
 which indicates that the function takes a variable number of arguments.
 Variable argument functions can access their arguments with the <a
  href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
 <h5>Examples:</h5>
 <p>
 <table border="0" cellpadding="0" cellspacing="0">
   <tbody>
     <tr>
       <td><tt>int (int)</tt></td>
       <td>: function taking an <tt>int</tt>, returning an <tt>int</tt></td>
     </tr>
     <tr>
       <td><tt>float (int, int *) *</tt></td>
       <td>: <a href="#t_pointer">Pointer</a> to a function that takes
 an <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
 returning <tt>float</tt>.</td>
     </tr>
     <tr>
       <td><tt>int (sbyte *, ...)</tt></td>
       <td>: A vararg function that takes at least one <a
  href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C),
 which       returns an integer.  This is the signature for <tt>printf</tt>
 in LLVM.</td>
     </tr>
   </tbody>
 </table>
 </p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
 <div class="doc_text">
 <h5>Overview:</h5>
 <p>The structure type is used to represent a collection of data members
 together in memory.  The packing of the field types is defined to match
 the ABI of the underlying processor.  The elements of a structure may
 be any type that has a size.</p>
 <p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
 and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
 field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
 instruction.</p>
 <h5>Syntax:</h5>
 <pre>  { &lt;type list&gt; }<br></pre>
 <h5>Examples:</h5>
 <p>
 <table border="0" cellpadding="0" cellspacing="0">
   <tbody>
     <tr>
       <td><tt>{ int, int, int }</tt></td>
       <td>: a triple of three <tt>int</tt> values</td>
     </tr>
     <tr>
       <td><tt>{ float, int (int) * }</tt></td>
       <td>: A pair, where the first element is a <tt>float</tt> and the
 second       element is a <a href="#t_pointer">pointer</a> to a <a
  href="t_function">function</a> that takes an <tt>int</tt>, returning
 an <tt>int</tt>.</td>
     </tr>
   </tbody>
 </table>
 </p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
 <div class="doc_text">
 <h5>Overview:</h5>
 <p>As in many languages, the pointer type represents a pointer or
 reference to another object, which must live in memory.</p>
 <h5>Syntax:</h5>
 <pre>  &lt;type&gt; *<br></pre>
 <h5>Examples:</h5>
 <p>
 <table border="0" cellpadding="0" cellspacing="0">
   <tbody>
     <tr>
       <td><tt>[4x int]*</tt></td>
       <td>: <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a>
 of four <tt>int</tt> values</td>
     </tr>
     <tr>
       <td><tt>int (int *) *</tt></td>
       <td>: A <a href="#t_pointer">pointer</a> to a <a
  href="t_function">function</a> that takes an <tt>int</tt>, returning
 an <tt>int</tt>.</td>
     </tr>
   </tbody>
 </table>
 </p>
 </div>
 <!-- _______________________________________________________________________ --><!--
 <div class="doc_subsubsection">
   <a name="t_packed">Packed Type</a>
 </div>

 <div class="doc_text">

 Mention/decide that packed types work with saturation or not. Maybe have a packed+saturated type in addition to just a packed type.<p>

 Packed types should be 'nonsaturated' because standard data types are not saturated.  Maybe have a saturated packed type?<p>

 </div>

 --><!-- *********************************************************************** -->
 <div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
 <!-- *********************************************************************** --><!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="modulestructure">Module Structure</a> </div>
 <div class="doc_text">
 <p>LLVM programs are composed of "Module"s, each of which is a
 translation unit of the input programs.  Each module consists of
 functions, global variables, and symbol table entries.  Modules may be
 combined together with the LLVM linker, which merges function (and
 global variable) definitions, resolves forward declarations, and merges
 symbol table entries. Here is an example of the "hello world" module:</p>
 <pre><i>; Declare the string constant as a global constant...</i>
 <a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
  href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00"          <i>; [13 x sbyte]*</i>

 <i>; External declaration of the puts function</i>
 <a href="#functionstructure">declare</a> int %puts(sbyte*)                                            <i>; int(sbyte*)* </i>

 <i>; Definition of main function</i>
 int %main() {                                                        <i>; int()* </i>
         <i>; Convert [13x sbyte]* to sbyte *...</i>
         %cast210 = <a
  href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>

         <i>; Call puts function to write out the string to stdout...</i>
         <a
  href="#i_call">call</a> int %puts(sbyte* %cast210)                              <i>; int</i>
         <a
  href="#i_ret">ret</a> int 0<br>}<br></pre>
 <p>This example is made up of a <a href="#globalvars">global variable</a>
 named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
 function, and a <a href="#functionstructure">function definition</a>
 for "<tt>main</tt>".</p>
 <a name="linkage"> In general, a module is made up of a list of global
 values, where both functions and global variables are global values.
 Global values are represented by a pointer to a memory location (in
 this case, a pointer to an array of char, and a pointer to a function),
 and have one of the following linkage types:</a>
 <p> </p>
 <dl>
   <a name="linkage_internal"> <dt><tt><b>internal</b></tt> </dt>
   <dd>Global values with internal linkage are only directly accessible
 by objects in the current module.  In particular, linking code into a
 module with an internal global value may cause the internal to be
 renamed as necessary to avoid collisions.  Because the symbol is
 internal to the module, all references can be updated.  This
 corresponds to the notion of the '<tt>static</tt>' keyword in C, or the
 idea of "anonymous namespaces" in C++.
     <p> </p>
   </dd>
   </a><a name="linkage_linkonce"> <dt><tt><b>linkonce</b></tt>: </dt>
   <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt>
 linkage, with the twist that linking together two modules defining the
 same <tt>linkonce</tt> globals will cause one of the globals to be
 discarded.  This is typically used to implement inline functions.
 Unreferenced <tt>linkonce</tt> globals are allowed to be discarded.
     <p> </p>
   </dd>
   </a><a name="linkage_weak"> <dt><tt><b>weak</b></tt>: </dt>
   <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt>
 linkage, except that unreferenced <tt>weak</tt> globals may not be
 discarded.  This is used to implement constructs in C such as "<tt>int
 X;</tt>" at global scope.
     <p> </p>
   </dd>
   </a><a name="linkage_appending"> <dt><tt><b>appending</b></tt>: </dt>
   <dd>"<tt>appending</tt>" linkage may only be applied to global
 variables of pointer to array type.  When two global variables with
 appending linkage are linked together, the two global arrays are
 appended together.  This is the LLVM, typesafe, equivalent of having
 the system linker append together "sections" with identical names when
 .o files are linked.
     <p> </p>
   </dd>
   </a><a name="linkage_external"> <dt><tt><b>externally visible</b></tt>:</dt>
   <dd>If none of the above identifiers are used, the global is
 externally visible, meaning that it participates in linkage and can be
 used to resolve external symbol references.
     <p> </p>
   </dd>
   </a>
 </dl>
 <p> </p>
 <p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
 variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
 variable and was linked with this one, one of the two would be renamed,
 preventing a collision.  Since "<tt>main</tt>" and "<tt>puts</tt>" are
 external (i.e., lacking any linkage declarations), they are accessible
 outside of the current module.  It is illegal for a function <i>declaration</i>
 to have any linkage type other than "externally visible".</a></p>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="globalvars">Global Variables</a> </div>
 <div class="doc_text">
 <p>Global variables define regions of memory allocated at compilation
 time instead of run-time.  Global variables may optionally be
 initialized.  A variable may be defined as a global "constant", which
 indicates that the contents of the variable will never be modified
 (opening options for optimization).  Constants must always have an
 initial value.</p>
 <p>As SSA values, global variables define pointer values that are in
 scope (i.e. they dominate) for all basic blocks in the program.  Global
 variables always define a pointer to their "content" type because they
 describe a region of memory, and all memory objects in LLVM are
 accessed through pointers.</p>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="functionstructure">Functions</a> </div>
 <div class="doc_text">
 <p>LLVM function definitions are composed of a (possibly empty)
 argument list, an opening curly brace, a list of basic blocks, and a
 closing curly brace.  LLVM function declarations are defined with the "<tt>declare</tt>"
 keyword, a function name, and a function signature.</p>
 <p>A function definition contains a list of basic blocks, forming the
 CFG for the function.  Each basic block may optionally start with a
 label (giving the basic block a symbol table entry), contains a list of
 instructions, and ends with a <a href="#terminators">terminator</a>
 instruction (such as a branch or function return).</p>
 <p>The first basic block in program is special in two ways: it is
 immediately executed on entrance to the function, and it is not allowed
 to have predecessor basic blocks (i.e. there can not be any branches to
 the entry block of a function).  Because the block can have no
 predecessors, it also cannot have any <a href="#i_phi">PHI nodes</a>.</p>
 <p>
 LLVM functions are identified by their name and type signature.  Hence, two
 functions with the same name but different parameter lists or return values
 are considered different functions, and LLVM will resolves references to each
 appropriately.
 </p>
 </div>
 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
 <!-- *********************************************************************** -->
 <div class="doc_text">
 <p>The LLVM instruction set consists of several different
 classifications of instructions: <a href="#terminators">terminator
 instructions</a>, <a href="#binaryops">binary instructions</a>, <a
  href="#memoryops">memory instructions</a>, and <a href="#otherops">other
 instructions</a>.</p>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="terminators">Terminator
 Instructions</a> </div>
 <div class="doc_text">
 <p>As mentioned <a href="#functionstructure">previously</a>, every
 basic block in a program ends with a "Terminator" instruction, which
 indicates which block should be executed after the current block is
 finished. These terminator instructions typically yield a '<tt>void</tt>'
 value: they produce control flow, not values (the one exception being
 the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
 <p>There are five different terminator instructions: the '<a
  href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
 instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
 the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, and the '<a
  href="#i_unwind"><tt>unwind</tt></a>' instruction.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  ret &lt;type&gt; &lt;value&gt;       <i>; Return a value from a non-void function</i>
   ret void                 <i>; Return from void function</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>ret</tt>' instruction is used to return control flow (and a
 value) from a function, back to the caller.</p>
 <p>There are two forms of the '<tt>ret</tt>' instructruction: one that
 returns a value and then causes control flow, and one that just causes
 control flow to occur.</p>
 <h5>Arguments:</h5>
 <p>The '<tt>ret</tt>' instruction may return any '<a
  href="#t_firstclass">first class</a>' type.  Notice that a function is
 not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
 instruction inside of the function that returns a value that does not
 match the return type of the function.</p>
 <h5>Semantics:</h5>
 <p>When the '<tt>ret</tt>' instruction is executed, control flow
 returns back to the calling function's context.  If the caller is a "<a
  href="#i_call"><tt>call</tt></a> instruction, execution continues at
 the instruction after the call.  If the caller was an "<a
  href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
 at the beginning "normal" of the destination block.  If the instruction
 returns a value, that value shall set the call or invoke instruction's
 return value.</p>
 <h5>Example:</h5>
 <pre>  ret int 5                       <i>; Return an integer value of 5</i>
   ret void                        <i>; Return from a void function</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  br bool &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br>  br label &lt;dest&gt;          <i>; Unconditional branch</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>br</tt>' instruction is used to cause control flow to
 transfer to a different basic block in the current function.  There are
 two forms of this instruction, corresponding to a conditional branch
 and an unconditional branch.</p>
 <h5>Arguments:</h5>
 <p>The conditional branch form of the '<tt>br</tt>' instruction takes a
 single '<tt>bool</tt>' value and two '<tt>label</tt>' values.  The
 unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
 value as a target.</p>
 <h5>Semantics:</h5>
 <p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
 argument is evaluated.  If the value is <tt>true</tt>, control flows
 to the '<tt>iftrue</tt>' <tt>label</tt> argument.  If "cond" is <tt>false</tt>,
 control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
 <h5>Example:</h5>
 <pre>Test:<br>  %cond = <a href="#i_setcc">seteq</a> int %a, %b<br>  br bool %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br>  <a
  href="#i_ret">ret</a> int 1<br>IfUnequal:<br>  <a href="#i_ret">ret</a> int 0<br></pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_switch">'<tt>switch</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  switch uint &lt;value&gt;, label &lt;defaultdest&gt; [ int &lt;val&gt;, label &amp;dest&gt;, ... ]<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>switch</tt>' instruction is used to transfer control flow
 to one of several different places.  It is a generalization of the '<tt>br</tt>'
 instruction, allowing a branch to occur to one of many possible
 destinations.</p>
 <h5>Arguments:</h5>
 <p>The '<tt>switch</tt>' instruction uses three parameters: a '<tt>uint</tt>'
 comparison value '<tt>value</tt>', a default '<tt>label</tt>'
 destination, and an array of pairs of comparison value constants and '<tt>label</tt>'s.</p>
 <h5>Semantics:</h5>
 <p>The <tt>switch</tt> instruction specifies a table of values and
 destinations. When the '<tt>switch</tt>' instruction is executed, this
 table is searched for the given value.  If the value is found, the
 corresponding destination is branched to, otherwise the default value
 it transfered to.</p>
 <h5>Implementation:</h5>
 <p>Depending on properties of the target machine and the particular <tt>switch</tt>
 instruction, this instruction may be code generated as a series of
 chained conditional branches, or with a lookup table.</p>
 <h5>Example:</h5>
 <pre>  <i>; Emulate a conditional br instruction</i>
   %Val = <a
  href="#i_cast">cast</a> bool %value to uint<br>  switch uint %Val, label %truedest [int 0, label %falsedest ]<br><br>  <i>; Emulate an unconditional br instruction</i>
   switch uint 0, label %dest [ ]

   <i>; Implement a jump table:</i>
   switch uint %val, label %otherwise [ int 0, label %onzero,
                                        int 1, label %onone,
                                        int 2, label %ontwo ]
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_invoke">'<tt>invoke</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = invoke &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)<br>                 to label &lt;normal label&gt; except label &lt;exception label&gt;<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>invoke</tt>' instruction causes control to transfer to a
 specified function, with the possibility of control flow transfer to
 either the '<tt>normal</tt>' <tt>label</tt> label or the '<tt>exception</tt>'<tt>label</tt>.
 If the callee function returns with the "<tt><a href="#i_ret">ret</a></tt>"
 instruction, control flow will return to the "normal" label.  If the
 callee (or any indirect callees) returns with the "<a href="#i_unwind"><tt>unwind</tt></a>"
 instruction, control is interrupted, and continued at the dynamically
 nearest "except" label.</p>
 <h5>Arguments:</h5>
 <p>This instruction requires several arguments:</p>
 <ol>
   <li>'<tt>ptr to function ty</tt>': shall be the signature of the
 pointer to function value being invoked.  In most cases, this is a
 direct function invocation, but indirect <tt>invoke</tt>s are just as
 possible, branching off an arbitrary pointer to function value. </li>
   <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer
 to a function to be invoked. </li>
   <li>'<tt>function args</tt>': argument list whose types match the
 function signature argument types.  If the function signature indicates
 the function accepts a variable number of arguments, the extra
 arguments can be specified. </li>
   <li>'<tt>normal label</tt>': the label reached when the called
 function executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
   <li>'<tt>exception label</tt>': the label reached when a callee
 returns with the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
 </ol>
 <h5>Semantics:</h5>
 <p>This instruction is designed to operate as a standard '<tt><a
  href="#i_call">call</a></tt>' instruction in most regards.  The
 primary difference is that it establishes an association with a label,
 which is used by the runtime library to unwind the stack.</p>
 <p>This instruction is used in languages with destructors to ensure
 that proper cleanup is performed in the case of either a <tt>longjmp</tt>
 or a thrown exception.  Additionally, this is important for
 implementation of '<tt>catch</tt>' clauses in high-level languages that
 support them.</p>
 <h5>Example:</h5>
 <pre>  %retval = invoke int %Test(int 15)<br>              to label %Continue<br>              except label %TestCleanup     <i>; {int}:retval set</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  unwind<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing
 control flow at the first callee in the dynamic call stack which used
 an <a href="#i_invoke"><tt>invoke</tt></a> instruction to perform the
 call.  This is primarily used to implement exception handling.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>unwind</tt>' intrinsic causes execution of the current
 function to immediately halt.  The dynamic call stack is then searched
 for the first <a href="#i_invoke"><tt>invoke</tt></a> instruction on
 the call stack.  Once found, execution continues at the "exceptional"
 destination block specified by the <tt>invoke</tt> instruction.  If
 there is no <tt>invoke</tt> instruction in the dynamic call chain,
 undefined behavior results.</p>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
 <div class="doc_text">
 <p>Binary operators are used to do most of the computation in a
 program.  They require two operands, execute an operation on them, and
 produce a single value. The result value of a binary operator is not
 necessarily the same type as its operands.</p>
 <p>There are several different binary operators:</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>add</tt>' instruction must be either <a
  href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
 values. Both arguments must have identical types.</p>
 <h5>Semantics:</h5>
 <p>The value produced is the integer or floating point sum of the two
 operands.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = add int 4, %var          <i>; yields {int}:result = 4 + %var</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>sub</tt>' instruction returns the difference of its two
 operands.</p>
 <p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
 instruction present in most other intermediate representations.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
  href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
 values. Both arguments must have identical types.</p>
 <h5>Semantics:</h5>
 <p>The value produced is the integer or floating point difference of
 the two operands.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = sub int 4, %var          <i>; yields {int}:result = 4 - %var</i>
   &lt;result&gt; = sub int 0, %val          <i>; yields {int}:result = -%var</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The  '<tt>mul</tt>' instruction returns the product of its two
 operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
  href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
 values. Both arguments must have identical types.</p>
 <h5>Semantics:</h5>
 <p>The value produced is the integer or floating point product of the
 two operands.</p>
 <p>There is no signed vs unsigned multiplication.  The appropriate
 action is taken based on the type of the operand.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = mul int 4, %var          <i>; yields {int}:result = 4 * %var</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>div</tt>' instruction returns the quotient of its two
 operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>div</tt>' instruction must be either <a
  href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
 values. Both arguments must have identical types.</p>
 <h5>Semantics:</h5>
 <p>The value produced is the integer or floating point quotient of the
 two operands.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = div int 4, %var          <i>; yields {int}:result = 4 / %var</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>rem</tt>' instruction returns the remainder from the
 division of its two operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
  href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
 values. Both arguments must have identical types.</p>
 <h5>Semantics:</h5>
 <p>This returns the <i>remainder</i> of a division (where the result
 has the same sign as the divisor), not the <i>modulus</i> (where the
 result has the same sign as the dividend) of a value.  For more
 information about the difference, see: <a
  href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
 Math Forum</a>.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = rem int 4, %var          <i>; yields {int}:result = 4 % %var</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
 Instructions</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {bool}:result</i>
   &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {bool}:result</i>
   &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {bool}:result</i>
   &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {bool}:result</i>
   &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {bool}:result</i>
   &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {bool}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
 value based on a comparison of their two operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
 be of <a href="#t_firstclass">first class</a> type (it is not possible
 to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
 or '<tt>void</tt>' values, etc...).  Both arguments must have identical
 types.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
 value if both operands are equal.<br>
 The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
 value if both operands are unequal.<br>
 The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
 value if the first operand is less than the second operand.<br>
 The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
 value if the first operand is greater than the second operand.<br>
 The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
 value if the first operand is less than or equal to the second operand.<br>
 The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
 value if the first operand is greater than or equal to the second
 operand.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = seteq int   4, 5        <i>; yields {bool}:result = false</i>
   &lt;result&gt; = setne float 4, 5        <i>; yields {bool}:result = true</i>
   &lt;result&gt; = setlt uint  4, 5        <i>; yields {bool}:result = true</i>
   &lt;result&gt; = setgt sbyte 4, 5        <i>; yields {bool}:result = false</i>
   &lt;result&gt; = setle sbyte 4, 5        <i>; yields {bool}:result = true</i>
   &lt;result&gt; = setge sbyte 4, 5        <i>; yields {bool}:result = false</i>
 </pre>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
 Operations</a> </div>
 <div class="doc_text">
 <p>Bitwise binary operators are used to do various forms of
 bit-twiddling in a program.  They are generally very efficient
 instructions, and can commonly be strength reduced from other
 instructions.  They require two operands, execute an operation on them,
 and produce a single value.  The resulting value of the bitwise binary
 operators is always the same type as its first operand.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>and</tt>' instruction returns the bitwise logical and of
 its two operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>and</tt>' instruction must be <a
  href="#t_integral">integral</a> values.  Both arguments must have
 identical types.</p>
 <h5>Semantics:</h5>
 <p>The truth table used for the '<tt>and</tt>' instruction is:</p>
 <p> </p>
 <center>
 <table border="1" cellspacing="0" cellpadding="4">
   <tbody>
     <tr>
       <td>In0</td>
       <td>In1</td>
       <td>Out</td>
     </tr>
     <tr>
       <td>0</td>
       <td>0</td>
       <td>0</td>
     </tr>
     <tr>
       <td>0</td>
       <td>1</td>
       <td>0</td>
     </tr>
     <tr>
       <td>1</td>
       <td>0</td>
       <td>0</td>
     </tr>
     <tr>
       <td>1</td>
       <td>1</td>
       <td>1</td>
     </tr>
   </tbody>
 </table>
 </center>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = and int 4, %var         <i>; yields {int}:result = 4 &amp; %var</i>
   &lt;result&gt; = and int 15, 40          <i>; yields {int}:result = 8</i>
   &lt;result&gt; = and int 4, 8            <i>; yields {int}:result = 0</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
 or of its two operands.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>or</tt>' instruction must be <a
  href="#t_integral">integral</a> values.  Both arguments must have
 identical types.</p>
 <h5>Semantics:</h5>
 <p>The truth table used for the '<tt>or</tt>' instruction is:</p>
 <p> </p>
 <center>
 <table border="1" cellspacing="0" cellpadding="4">
   <tbody>
     <tr>
       <td>In0</td>
       <td>In1</td>
       <td>Out</td>
     </tr>
     <tr>
       <td>0</td>
       <td>0</td>
       <td>0</td>
     </tr>
     <tr>
       <td>0</td>
       <td>1</td>
       <td>1</td>
     </tr>
     <tr>
       <td>1</td>
       <td>0</td>
       <td>1</td>
     </tr>
     <tr>
       <td>1</td>
       <td>1</td>
       <td>1</td>
     </tr>
   </tbody>
 </table>
 </center>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = or int 4, %var         <i>; yields {int}:result = 4 | %var</i>
   &lt;result&gt; = or int 15, 40          <i>; yields {int}:result = 47</i>
   &lt;result&gt; = or int 4, 8            <i>; yields {int}:result = 12</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
 or of its two operands.  The <tt>xor</tt> is used to implement the
 "one's complement" operation, which is the "~" operator in C.</p>
 <h5>Arguments:</h5>
 <p>The two arguments to the '<tt>xor</tt>' instruction must be <a
  href="#t_integral">integral</a> values.  Both arguments must have
 identical types.</p>
 <h5>Semantics:</h5>
 <p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
 <p> </p>
 <center>
 <table border="1" cellspacing="0" cellpadding="4">
   <tbody>
     <tr>
       <td>In0</td>
       <td>In1</td>
       <td>Out</td>
     </tr>
     <tr>
       <td>0</td>
       <td>0</td>
       <td>0</td>
     </tr>
     <tr>
       <td>0</td>
       <td>1</td>
       <td>1</td>
     </tr>
     <tr>
       <td>1</td>
       <td>0</td>
       <td>1</td>
     </tr>
     <tr>
       <td>1</td>
       <td>1</td>
       <td>0</td>
     </tr>
   </tbody>
 </table>
 </center>
 <p> </p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = xor int 4, %var         <i>; yields {int}:result = 4 ^ %var</i>
   &lt;result&gt; = xor int 15, 40          <i>; yields {int}:result = 39</i>
   &lt;result&gt; = xor int 4, 8            <i>; yields {int}:result = 12</i>
   &lt;result&gt; = xor int %V, -1          <i>; yields {int}:result = ~%V</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>shl</tt>' instruction returns the first operand shifted to
 the left a specified number of bits.</p>
 <h5>Arguments:</h5>
 <p>The first argument to the '<tt>shl</tt>' instruction must be an <a
  href="#t_integer">integer</a> type.  The second argument must be an '<tt>ubyte</tt>'
 type.</p>
 <h5>Semantics:</h5>
 <p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = shl int 4, ubyte %var   <i>; yields {int}:result = 4 &lt;&lt; %var</i>
   &lt;result&gt; = shl int 4, ubyte 2      <i>; yields {int}:result = 16</i>
   &lt;result&gt; = shl int 1, ubyte 10     <i>; yields {int}:result = 1024</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt;   <i>; yields {ty}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>shr</tt>' instruction returns the first operand shifted to
 the right a specified number of bits.</p>
 <h5>Arguments:</h5>
 <p>The first argument to the '<tt>shr</tt>' instruction must be an <a
  href="#t_integer">integer</a> type.  The second argument must be an '<tt>ubyte</tt>'
 type.</p>
 <h5>Semantics:</h5>
 <p>If the first argument is a <a href="#t_signed">signed</a> type, the
 most significant bit is duplicated in the newly free'd bit positions.
 If the first argument is unsigned, zero bits shall fill the empty
 positions.</p>
 <h5>Example:</h5>
 <pre>  &lt;result&gt; = shr int 4, ubyte %var   <i>; yields {int}:result = 4 &gt;&gt; %var</i>
   &lt;result&gt; = shr uint 4, ubyte 1     <i>; yields {uint}:result = 2</i>
   &lt;result&gt; = shr int 4, ubyte 2      <i>; yields {int}:result = 1</i>
   &lt;result&gt; = shr sbyte 4, ubyte 3    <i>; yields {sbyte}:result = 0</i>
   &lt;result&gt; = shr sbyte -2, ubyte 1   <i>; yields {sbyte}:result = -1</i>
 </pre>
 </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="memoryops">Memory Access
 Operations</a></div>
 <div class="doc_text">
 <p>A key design point of an SSA-based representation is how it
 represents memory.  In LLVM, no memory locations are in SSA form, which
 makes things very simple.  This section describes how to read, write,
 allocate and free memory in LLVM.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt;     <i>; yields {type*}:result</i>
   &lt;result&gt; = malloc &lt;type&gt;                         <i>; yields {type*}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>malloc</tt>' instruction allocates memory from the system
 heap and returns a pointer to it.</p>
 <h5>Arguments:</h5>
 <p>The the '<tt>malloc</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
 bytes of memory from the operating system, and returns a pointer of the
 appropriate type to the program.  The second form of the instruction is
 a shorter version of the first instruction that defaults to allocating
 one element.</p>
 <p>'<tt>type</tt>' must be a sized type.</p>
 <h5>Semantics:</h5>
 <p>Memory is allocated using the system "<tt>malloc</tt>" function, and
 a pointer is returned.</p>
 <h5>Example:</h5>
 <pre>  %array  = malloc [4 x ubyte ]                    <i>; yields {[%4 x ubyte]*}:array</i>

   %size   = <a
  href="#i_add">add</a> uint 2, 2                          <i>; yields {uint}:size = uint 4</i>
   %array1 = malloc ubyte, uint 4                   <i>; yields {ubyte*}:array1</i>
   %array2 = malloc [12 x ubyte], uint %size        <i>; yields {[12 x ubyte]*}:array2</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_free">'<tt>free</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  free &lt;type&gt; &lt;value&gt;                              <i>; yields {void}</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>free</tt>' instruction returns memory back to the unused
 memory heap, to be reallocated in the future.</p>
 <p> </p>
 <h5>Arguments:</h5>
 <p>'<tt>value</tt>' shall be a pointer value that points to a value
 that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
 instruction.</p>
 <h5>Semantics:</h5>
 <p>Access to the memory pointed to by the pointer is not longer defined
 after this instruction executes.</p>
 <h5>Example:</h5>
 <pre>  %array  = <a href="#i_malloc">malloc</a> [4 x ubyte]                    <i>; yields {[4 x ubyte]*}:array</i>
             free   [4 x ubyte]* %array
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt;  <i>; yields {type*}:result</i>
   &lt;result&gt; = alloca &lt;type&gt;                      <i>; yields {type*}:result</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>alloca</tt>' instruction allocates memory on the current
 stack frame of the procedure that is live until the current function
 returns to its caller.</p>
 <h5>Arguments:</h5>
 <p>The the '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
 bytes of memory on the runtime stack, returning a pointer of the
 appropriate type to the program.  The second form of the instruction is
 a shorter version of the first that defaults to allocating one element.</p>
 <p>'<tt>type</tt>' may be any sized type.</p>
 <h5>Semantics:</h5>
 <p>Memory is allocated, a pointer is returned.  '<tt>alloca</tt>'d
 memory is automatically released when the function returns.  The '<tt>alloca</tt>'
 instruction is commonly used to represent automatic variables that must
 have an address available.  When the function returns (either with the <tt><a
  href="#i_ret">ret</a></tt> or <tt><a href="#i_invoke">invoke</a></tt>
 instructions), the memory is reclaimed.</p>
 <h5>Example:</h5>
 <pre>  %ptr = alloca int                              <i>; yields {int*}:ptr</i>
   %ptr = alloca int, uint 4                      <i>; yields {int*}:ptr</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;<br>  &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>load</tt>' instruction is used to read from memory.</p>
 <h5>Arguments:</h5>
 <p>The argument to the '<tt>load</tt>' instruction specifies the memory
 address to load from.  The pointer must point to a <a
  href="t_firstclass">first class</a> type.  If the <tt>load</tt> is
 marked as <tt>volatile</tt> then the optimizer is not allowed to modify
 the number or order of execution of this <tt>load</tt> with other
 volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
 instructions. </p>
 <h5>Semantics:</h5>
 <p>The location of memory pointed to is loaded.</p>
 <h5>Examples:</h5>
 <pre>  %ptr = <a href="#i_alloca">alloca</a> int                               <i>; yields {int*}:ptr</i>
   <a
  href="#i_store">store</a> int 3, int* %ptr                          <i>; yields {void}</i>
   %val = load int* %ptr                           <i>; yields {int}:val = int 3</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
 Instruction</a> </div>
 <h5>Syntax:</h5>
 <pre>  store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;                   <i>; yields {void}</i>
   volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;                   <i>; yields {void}</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>store</tt>' instruction is used to write to memory.</p>
 <h5>Arguments:</h5>
 <p>There are two arguments to the '<tt>store</tt>' instruction: a value
 to store and an address to store it into.  The type of the '<tt>&lt;pointer&gt;</tt>'
 operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
 operand. If the <tt>store</tt> is marked as <tt>volatile</tt> then the
 optimizer is not allowed to modify the number or order of execution of
 this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
  href="#i_store">store</a></tt> instructions.</p>
 <h5>Semantics:</h5>
 <p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
 at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
 <h5>Example:</h5>
 <pre>  %ptr = <a href="#i_alloca">alloca</a> int                               <i>; yields {int*}:ptr</i>
   <a
  href="#i_store">store</a> int 3, int* %ptr                          <i>; yields {void}</i>
   %val = load int* %ptr                           <i>; yields {int}:val = int 3</i>
 </pre>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_getelementptr">'<tt>getelementptr</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, long &lt;aidx&gt;|, ubyte &lt;sidx&gt;}*<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>getelementptr</tt>' instruction is used to get the address
 of a subelement of an aggregate data structure.</p>
 <h5>Arguments:</h5>
 <p>This instruction takes a list of <tt>long</tt> values and <tt>ubyte</tt>
 constants that indicate what form of addressing to perform.  The actual
 types of the arguments provided depend on the type of the first pointer
 argument.  The '<tt>getelementptr</tt>' instruction is used to index
 down through the type levels of a structure.</p>
 <p>For example, let's consider a C code fragment and how it gets
 compiled to LLVM:</p>
 <pre>struct RT {<br>  char A;<br>  int B[10][20];<br>  char C;<br>};<br>struct ST {<br>  int X;<br>  double Y;<br>  struct RT Z;<br>};<br><br>int *foo(struct ST *s) {<br>  return &amp;s[1].Z.B[5][13];<br>}<br></pre>
 <p>The LLVM code generated by the GCC frontend is:</p>
 <pre>%RT = type { sbyte, [10 x [20 x int]], sbyte }<br>%ST = type { int, double, %RT }<br><br>int* "foo"(%ST* %s) {<br>  %reg = getelementptr %ST* %s, long 1, ubyte 2, ubyte 1, long 5, long 13<br>  ret int* %reg<br>}<br></pre>
 <h5>Semantics:</h5>
 <p>The index types specified for the '<tt>getelementptr</tt>'
 instruction depend on the pointer type that is being index into. <a
  href="t_pointer">Pointer</a> and <a href="t_array">array</a> types
 require '<tt>long</tt>' values, and <a href="t_struct">structure</a>
 types require '<tt>ubyte</tt>' <b>constants</b>.</p>
 <p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
 type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int,
 double, %RT }</tt>' type, a structure.  The second index indexes into
 the third element of the structure, yielding a '<tt>%RT</tt>' = '<tt>{
 sbyte, [10 x [20 x int]], sbyte }</tt>' type, another structure.  The
 third index indexes into the second element of the structure, yielding
 a '<tt>[10 x [20 x int]]</tt>' type, an array.  The two dimensions of
 the array are subscripted into, yielding an '<tt>int</tt>' type.  The '<tt>getelementptr</tt>'
 instruction return a pointer to this element, thus yielding a '<tt>int*</tt>'
 type.</p>
 <p>Note that it is perfectly legal to index partially through a
 structure, returning a pointer to an inner element.  Because of this,
 the LLVM code for the given testcase is equivalent to:</p>
 <pre>int* "foo"(%ST* %s) {<br>  %t1 = getelementptr %ST* %s , long 1                        <i>; yields %ST*:%t1</i>
   %t2 = getelementptr %ST* %t1, long 0, ubyte 2               <i>; yields %RT*:%t2</i>
   %t3 = getelementptr %RT* %t2, long 0, ubyte 1               <i>; yields [10 x [20 x int]]*:%t3</i>
   %t4 = getelementptr [10 x [20 x int]]* %t3, long 0, long 5  <i>; yields [20 x int]*:%t4</i>
   %t5 = getelementptr [20 x int]* %t4, long 0, long 13        <i>; yields int*:%t5</i>
   ret int* %t5
 }
 </pre>
 <h5>Example:</h5>
 <pre>  <i>; yields [12 x ubyte]*:aptr</i>
   %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, ubyte 1<br></pre>
 <h5>&nbsp;Note To The Novice:</h5>
 When using indexing into global arrays with the  '<tt>getelementptr</tt>'
 instruction, you must remember that the&nbsp; </div>
 <!-- ======================================================================= -->
 <div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
 <div class="doc_text">
 <p>The instructions in this catagory are the "miscellaneous"
 instructions, which defy better classification.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
 the SSA graph representing the function.</p>
 <h5>Arguments:</h5>
 <p>The type of the incoming values are specified with the first type
 field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
 as arguments, with one pair for each predecessor basic block of the
 current block.  Only values of <a href="#t_firstclass">first class</a>
 type may be used as the value arguments to the PHI node.  Only labels
 may be used as the label arguments.</p>
 <p>There must be no non-phi instructions between the start of a basic
 block and the PHI instructions: i.e. PHI instructions must be first in
 a basic block.</p>
 <h5>Semantics:</h5>
 <p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
 value specified by the parameter, depending on which basic block we
 came from in the last <a href="#terminators">terminator</a> instruction.</p>
 <h5>Example:</h5>
 <pre>Loop:       ; Infinite loop that counts from 0 on up...<br>  %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br>  %nextindvar = add uint %indvar, 1<br>  br label %Loop<br></pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_cast">'<tt>cast .. to</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
 </pre>
 <h5>Overview:</h5>
 <p>The '<tt>cast</tt>' instruction is used as the primitive means to
 convert integers to floating point, change data type sizes, and break
 type safety (by casting pointers).</p>
 <h5>Arguments:</h5>
 <p>The '<tt>cast</tt>' instruction takes a value to cast, which must be
 a first class value, and a type to cast it to, which must also be a <a
  href="#t_firstclass">first class</a> type.</p>
 <h5>Semantics:</h5>
 <p>This instruction follows the C rules for explicit casts when
 determining how the data being cast must change to fit in its new
 container.</p>
 <p>When casting to bool, any value that would be considered true in the
 context of a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>'
 values, all else are '<tt>false</tt>'.</p>
 <p>When extending an integral value from a type of one signness to
 another (for example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value
 is sign-extended if the <b>source</b> value is signed, and
 zero-extended if the source value is unsigned. <tt>bool</tt> values
 are always zero extended into either zero or one.</p>
 <h5>Example:</h5>
 <pre>  %X = cast int 257 to ubyte              <i>; yields ubyte:1</i>
   %Y = cast int 123 to bool               <i>; yields bool:true</i>
 </pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>call</tt>' instruction represents a simple function call.</p>
 <h5>Arguments:</h5>
 <p>This instruction requires several arguments:</p>
 <ol>
   <li>
     <p>'<tt>ty</tt>': shall be the signature of the pointer to function
 value   being invoked.  The argument types must match the types implied
 by this   signature.</p>
   </li>
   <li>
     <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a
 function   to be invoked. In most cases, this is a direct function
 invocation, but   indirect <tt>call</tt>s are just as possible,
 calling an arbitrary pointer to   function values.</p>
   </li>
   <li>
     <p>'<tt>function args</tt>': argument list whose types match the
 function   signature argument types.  If the function signature
 indicates the function   accepts a variable number of arguments, the
 extra arguments can be   specified.</p>
   </li>
 </ol>
 <h5>Semantics:</h5>
 <p>The '<tt>call</tt>' instruction is used to cause control flow to
 transfer to a specified function, with its incoming arguments bound to
 the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
 instruction in the called function, control flow continues with the
 instruction after the function call, and the return value of the
 function is bound to the result argument.  This is a simpler case of
 the <a href="#i_invoke">invoke</a> instruction.</p>
 <h5>Example:</h5>
 <pre>  %retval = call int %test(int %argc)<br>  call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<br></pre>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_vanext">'<tt>vanext</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>vanext</tt>' instruction is used to access arguments passed
 through the "variable argument" area of a function call.  It is used to
 implement the <tt>va_arg</tt> macro in C.</p>
 <h5>Arguments:</h5>
 <p>This instruction takes a <tt>valist</tt> value and the type of the
 argument. It returns another <tt>valist</tt>.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>vanext</tt>' instruction advances the specified <tt>valist</tt>
 past an argument of the specified type.  In conjunction with the <a
  href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement
 the <tt>va_arg</tt> macro available in C.  For more information, see
 the variable argument handling <a href="#int_varargs">Intrinsic
 Functions</a>.</p>
 <p>It is legal for this instruction to be called in a function which
 does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
 function.</p>
 <p><tt>vanext</tt> is an LLVM instruction instead of an <a
  href="#intrinsics">intrinsic function</a> because it takes an type as
 an argument.</p>
 <h5>Example:</h5>
 <p>See the <a href="#int_varargs">variable argument processing</a>
 section.</p>
 </div>
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection"> <a name="i_vaarg">'<tt>vaarg</tt>'
 Instruction</a> </div>
 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  &lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>vaarg</tt>' instruction is used to access arguments passed
 through the "variable argument" area of a function call.  It is used to
 implement the <tt>va_arg</tt> macro in C.</p>
 <h5>Arguments:</h5>
 <p>This instruction takes a <tt>valist</tt> value and the type of the
 argument. It returns a value of the specified argument type.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>vaarg</tt>' instruction loads an argument of the specified
 type from the specified <tt>va_list</tt>.  In conjunction with the <a
  href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to
 implement the <tt>va_arg</tt> macro available in C.  For more
 information, see the variable argument handling <a href="#int_varargs">Intrinsic
 Functions</a>.</p>
 <p>It is legal for this instruction to be called in a function which
 does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
 function.</p>
 <p><tt>vaarg</tt> is an LLVM instruction instead of an <a
  href="#intrinsics">intrinsic function</a> because it takes an type as
 an argument.</p>
 <h5>Example:</h5>
 <p>See the <a href="#int_varargs">variable argument processing</a>
 section.</p>
 </div>

 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
 <!-- *********************************************************************** -->

 <div class="doc_text">

 <p>LLVM supports the notion of an "intrinsic function".  These functions have
 well known names and semantics, and are required to follow certain
 restrictions. Overall, these instructions represent an extension mechanism for
 the LLVM language that does not require changing all of the transformations in
 LLVM to add to the language (or the bytecode reader/writer, the parser,
 etc...).</p>

 <p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix, this
 prefix is reserved in LLVM for intrinsic names, thus functions may not be named
 this.  Intrinsic functions must always be external functions: you cannot define
 the body of intrinsic functions.  Intrinsic functions may only be used in call
 or invoke instructions: it is illegal to take the address of an intrinsic
 function.  Additionally, because intrinsic functions are part of the LLVM
 language, it is required that they all be documented here if any are added.</p>


 <p>
 Adding an intrinsic to LLVM is straight-forward if it is possible to express the
 concept in LLVM directly (ie, code generator support is not _required_).  To do
 this, extend the default implementation of the IntrinsicLowering class to handle
 the intrinsic.  Code generators use this class to lower intrinsics they do not
 understand to raw LLVM instructions that they do.
 </p>

 </div>

 <!-- ======================================================================= -->
 <div class="doc_subsection">
   <a name="int_varargs">Variable Argument Handling Intrinsics</a>
 </div>

 <div class="doc_text">
 <p>Variable argument support is defined in LLVM with the <a
  href="#i_vanext"><tt>vanext</tt></a> instruction and these three
 intrinsic functions.  These functions are related to the similarly
 named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
 <p>All of these functions operate on arguments that use a
 target-specific value type "<tt>va_list</tt>".  The LLVM assembly
 language reference manual does not define what this type is, so all
 transformations should be prepared to handle intrinsics with any type
 used.</p>
 <p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
 instruction and the variable argument handling intrinsic functions are
 used.</p>
 <pre>
 int %test(int %X, ...) {
   ; Initialize variable argument processing
   %ap = call sbyte* %<a href="#i_va_start">llvm.va_start</a>()

   ; Read a single integer argument
   %tmp = vaarg sbyte* %ap, int

   ; Advance to the next argument
   %ap2 = vanext sbyte* %ap, int

   ; Demonstrate usage of llvm.va_copy and llvm.va_end
   %aq = call sbyte* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)
   call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq)

   ; Stop processing of arguments.
   call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)
   ret int %tmp
 }
 </pre>
 </div>

 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
   <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
 </div>


 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  call va_list ()* %llvm.va_start()<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
 for subsequent use by the variable argument intrinsics.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
 macro available in C.  In a target-dependent way, it initializes and
 returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt>
 will produce the first variable argument passed to the function.  Unlike
 the C <tt>va_start</tt> macro, this intrinsic does not need to know the
 last argument of the function, the compiler can figure that out.</p>
 <p>Note that this intrinsic function is only legal to be called from
 within the body of a variable argument function.</p>
 </div>

 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
  <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
 </div>

 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  call void (va_list)* %llvm.va_end(va_list &lt;arglist&gt;)<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
 which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
 or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
 <h5>Arguments:</h5>
 <p>The argument is a <tt>va_list</tt> to destroy.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
 macro available in C.  In a target-dependent way, it destroys the <tt>va_list</tt>.
 Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
  href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
 with calls to <tt>llvm.va_end</tt>.</p>
 </div>

 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
   <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
 </div>

 <div class="doc_text">
 <h5>Syntax:</h5>
 <pre>  call va_list (va_list)* %llvm.va_copy(va_list &lt;destarglist&gt;)<br></pre>
 <h5>Overview:</h5>
 <p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument
 position from the source argument list to the destination argument list.</p>
 <h5>Arguments:</h5>
 <p>The argument is the <tt>va_list</tt> to copy.</p>
 <h5>Semantics:</h5>
 <p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
 macro available in C.  In a target-dependent way, it copies the source <tt>va_list</tt>
 element into the returned list.  This intrinsic is necessary because the <tt><a
  href="i_va_start">llvm.va_start</a></tt> intrinsic may be arbitrarily
 complex and require memory allocation, for example.</p>
 </div>

 <!-- ======================================================================= -->
 <div class="doc_subsection">
   <a name="int_libc">Standard C Library Intrinsics</a>
 </div>

 <div class="doc_text">
 <p>

 </p>

 </div>

 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
   <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
 </div>

 <div class="doc_text">

 <h5>Syntax:</h5>
 <pre>
   call void (sbyte*, sbyte*, uint, uint)* %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
                                                        uint &lt;len&gt;, uint &lt;align&gt;)
 </pre>

 <h5>Overview:</h5>

 <p>
 The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
 location to the destination location.
 </p>

 <p>
 Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
 does not return a value, and takes an extra alignment argument.
 </p>

 <h5>Arguments:</h5>

 <p>
 The first argument is a pointer to the destination, the second is a pointer to
 the source.  The third argument is an (arbitrarily sized) integer argument
 specifying the number of bytes to copy, and the fourth argument is the alignment
 of the source and destination locations.
 </p>

 <p>
 If the call to this intrinisic has an alignment value that is not 0 or 1, then
 the caller guarantees that the size of the copy is a multiple of the alignment
 and that both the source and destination pointers are aligned to that boundary.
 </p>

 <h5>Semantics:</h5>

 <p>
 The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
 location to the destination location, which are not allowed to overlap.  It
 copies "len" bytes of memory over.  If the argument is known to be aligned to
 some boundary, this can be specified as the fourth argument, otherwise it should
 be set to 0 or 1.
 </p>
 </div>


 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
   <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
 </div>

 <div class="doc_text">

 <h5>Syntax:</h5>
 <pre>
   call void (sbyte*, sbyte*, uint, uint)* %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
                                                        uint &lt;len&gt;, uint &lt;align&gt;)
 </pre>

 <h5>Overview:</h5>

 <p>
 The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
 location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
 intrinsic but allows the two memory locations to overlap.
 </p>

 <p>
 Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
 does not return a value, and takes an extra alignment argument.
 </p>

 <h5>Arguments:</h5>

 <p>
 The first argument is a pointer to the destination, the second is a pointer to
 the source.  The third argument is an (arbitrarily sized) integer argument
 specifying the number of bytes to copy, and the fourth argument is the alignment
 of the source and destination locations.
 </p>

 <p>
 If the call to this intrinisic has an alignment value that is not 0 or 1, then
 the caller guarantees that the size of the copy is a multiple of the alignment
 and that both the source and destination pointers are aligned to that boundary.
 </p>

 <h5>Semantics:</h5>

 <p>
 The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
 location to the destination location, which may overlap.  It
 copies "len" bytes of memory over.  If the argument is known to be aligned to
 some boundary, this can be specified as the fourth argument, otherwise it should
 be set to 0 or 1.
 </p>
 </div>


 <!-- ======================================================================= -->
 <div class="doc_subsection">
   <a name="int_debugger">Debugger Intrinsics</a>
 </div>

 <div class="doc_text">
 <p>
 The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
 are described in the <a
 href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
 Debugging</a> document.
 </p>
 </div>


 <!-- *********************************************************************** -->
 <hr>
 <div class="doc_footer">
 <address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> <br>
 Last modified: $Date$ </div>
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