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-<tr><td> <font size=+5 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>llvm Assembly Language Reference Manual</b></font></td>
-</tr></table>
-
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+ "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+ <title>LLVM Assembly Language Reference Manual</title>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+ <meta name="author" content="Chris Lattner">
+ <meta name="description"
+ content="LLVM Assembly Language Reference Manual.">
+ <link rel="stylesheet" href="llvm.css" type="text/css">
+</head>
+
+<body>
+
+<div class="doc_title"> LLVM Language Reference Manual </div>
<ol>
- <li><a href="#abstract">Abstract</a>
- <li><a href="#introduction">Introduction</a>
- <li><a href="#identifiers">Identifiers</a>
+ <li><a href="#abstract">Abstract</a></li>
+ <li><a href="#introduction">Introduction</a></li>
+ <li><a href="#identifiers">Identifiers</a></li>
+ <li><a href="#highlevel">High Level Structure</a>
+ <ol>
+ <li><a href="#modulestructure">Module Structure</a></li>
+ <li><a href="#linkage">Linkage Types</a></li>
+ <li><a href="#callingconv">Calling Conventions</a></li>
+ <li><a href="#globalvars">Global Variables</a></li>
+ <li><a href="#functionstructure">Functions</a></li>
+ <li><a href="#paramattrs">Parameter Attributes</a></li>
+ <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
+ <li><a href="#datalayout">Data Layout</a></li>
+ </ol>
+ </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><a href="#t_primitive">Primitive Types</a>
+ <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><a href="#t_function">Function Type</a>
- <li><a href="#t_pointer">Pointer Type</a>
- <li><a href="#t_struct" >Structure Type</a>
- <!-- <li><a href="#t_packed" >Packed Type</a> -->
+ <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_pstruct">Packed Structure Type</a></li>
+ <li><a href="#t_vector">Vector Type</a></li>
+ <li><a href="#t_opaque">Opaque Type</a></li>
</ol>
+ </li>
</ol>
- <li><a href="#highlevel">High Level Structure</a>
+ </li>
+ <li><a href="#constants">Constants</a>
+ <ol>
+ <li><a href="#simpleconstants">Simple Constants</a>
+ <li><a href="#aggregateconstants">Aggregate Constants</a>
+ <li><a href="#globalconstants">Global Variable and Function Addresses</a>
+ <li><a href="#undefvalues">Undefined Values</a>
+ <li><a href="#constantexprs">Constant Expressions</a>
+ </ol>
+ </li>
+ <li><a href="#othervalues">Other Values</a>
<ol>
- <li><a href="#modulestructure">Module Structure</a>
- <li><a href="#globalvars">Global Variables</a>
- <li><a href="#functionstructure">Function Structure</a>
+ <li><a href="#inlineasm">Inline Assembler Expressions</a>
</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><a href="#i_br" >'<tt>br</tt>' Instruction</a>
- <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a>
- <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a>
+ <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>
+ <li><a href="#i_unreachable">'<tt>unreachable</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><a href="#i_sub" >'<tt>sub</tt>' Instruction</a>
- <li><a href="#i_mul" >'<tt>mul</tt>' Instruction</a>
- <li><a href="#i_div" >'<tt>div</tt>' Instruction</a>
- <li><a href="#i_rem" >'<tt>rem</tt>' Instruction</a>
- <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a>
+ <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_udiv">'<tt>udiv</tt>' Instruction</a></li>
+ <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
+ <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
+ <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
+ <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
+ <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
</ol>
+ </li>
<li><a href="#bitwiseops">Bitwise Binary Operations</a>
<ol>
- <li><a href="#i_and">'<tt>and</tt>' Instruction</a>
- <li><a href="#i_or" >'<tt>or</tt>' Instruction</a>
- <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a>
- <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a>
- <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a>
+ <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
+ <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
+ <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
+ <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>
+ </ol>
+ </li>
+ <li><a href="#vectorops">Vector Operations</a>
+ <ol>
+ <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
+ <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
+ <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
+ </ol>
+ </li>
+ <li><a href="#memoryops">Memory Access and Addressing 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><a href="#memoryops">Memory Access Operations</a>
+ </li>
+ <li><a href="#convertops">Conversion Operations</a>
<ol>
- <li><a href="#i_malloc" >'<tt>malloc</tt>' Instruction</a>
- <li><a href="#i_free" >'<tt>free</tt>' Instruction</a>
- <li><a href="#i_alloca" >'<tt>alloca</tt>' Instruction</a>
- <li><a href="#i_load" >'<tt>load</tt>' Instruction</a>
- <li><a href="#i_store" >'<tt>store</tt>' Instruction</a>
- <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
+ <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
+ <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
+ <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
+ <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
+ <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
+ <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
+ <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
+ <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
+ <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
+ <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
+ <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
+ <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
</ol>
<li><a href="#otherops">Other Operations</a>
<ol>
- <li><a href="#i_phi" >'<tt>phi</tt>' Instruction</a>
- <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a>
- <li><a href="#i_call" >'<tt>call</tt>' Instruction</a>
+ <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
+ <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
+ <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
+ <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
+ <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
+ <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
</ol>
+ </li>
</ol>
-<!--
- <li><a href="#related">Related Work</a>
--->
-
- <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>
-
-
+ </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_gc">Accurate Garbage Collection Intrinsics</a>
+ <ol>
+ <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
+ <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
+ <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
+ </ol>
+ </li>
+ <li><a href="#int_codegen">Code Generator Intrinsics</a>
+ <ol>
+ <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
+ <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
+ <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
+ <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
+ <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
+ <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
+ <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</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>
+ <li><a href="#i_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
+ <li><a href="#i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
+ <li><a href="#i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
+ </ol>
+ </li>
+ <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
+ <ol>
+ <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
+ <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
+ <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
+ <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
+ </ol>
+ </li>
+ <li><a href="#int_debugger">Debugger intrinsics</a></li>
+ <li><a href="#int_eh">Exception Handling intrinsics</a></li>
+ </ol>
+ </li>
</ol>
+<div class="doc_author">
+ <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
+ and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
+</div>
<!-- *********************************************************************** -->
-<p><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="abstract">Abstract
-</b></font></td></tr></table><ul>
+<div class="doc_section"> <a name="abstract">Abstract </a></div>
<!-- *********************************************************************** -->
-<blockquote>
- 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.
-</blockquote>
-
-
-
+<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>
<!-- *********************************************************************** -->
-</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="introduction">Introduction
-</b></font></td></tr></table><ul>
+<div class="doc_section"> <a name="introduction">Introduction</a> </div>
<!-- *********************************************************************** -->
-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 dynamic 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>
-
-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 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 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>
<!-- _______________________________________________________________________ -->
-</ul><a name="wellformed"><h4><hr size=0>Well Formedness</h4><ul>
+<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
-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>
+<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
+ %x = <a href="#i_add">add</a> i32 1, %x
</pre>
-...because the definition of %x 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. -->
+<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>
<!-- *********************************************************************** -->
-</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="identifiers">Identifiers
-</b></font></td></tr></table><ul>
+<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
<!-- *********************************************************************** -->
-LLVM uses three different forms of identifiers, for different purposes:<p>
+<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>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>'.
-<li>Unnamed values are represented as an unsigned numeric value with a '%' prefix. For example, %12, %2, %44.
-</ol><p>
+ <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>
+
+ <li>Constants, which are described in a <a href="#constants">section about
+ constants</a>, below.</li>
+</ol>
-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>LLVM requires that 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>
-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>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_bitcast">bitcast</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_primitive">i32</a></tt>', etc...),
+and others. These reserved words cannot conflict with variable names, because
+none of them start with a '%' character.</p>
-Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>'
-by 8:<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>
-The easy way:
<pre>
- %result = <a href="#i_mul">mul</a> uint %X, 8
+ %result = <a href="#i_mul">mul</a> i32 %X, 8
</pre>
-After strength reduction:
+<p>After strength reduction:</p>
+
<pre>
- %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
+ %result = <a href="#i_shl">shl</a> i32 %X, i8 3
</pre>
-And the hard way:
+<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
+ <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
+ <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
+ %result = <a href="#i_add">add</a> i32 %1, %1
</pre>
-This last way of multiplying <tt>%X</tt> by 8 illustrates several important lexical features of LLVM:<p>
+<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>Unnamed temporaries are created when the result of a computation is not
- assigned to a named value.
-<li>Unnamed temporaries are numbered sequentially
-</ol><p>
-...and it also show a convention that we follow in this document. When
+ <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 shows 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>
-
-The one unintuitive 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>
+text.</p>
+</div>
<!-- *********************************************************************** -->
-</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="typesystem">Type System
-</b></font></td></tr></table><ul>
+<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
<!-- *********************************************************************** -->
-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>
+<!-- ======================================================================= -->
+<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
+</div>
+
+<div class="doc_text">
-<!-- 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> -->
+<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 i8 ]</a> c"hello world\0A\00" <i>; [13 x i8 ]*</i>
+<i>; External declaration of the puts function</i>
+<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
+
+<i>; Global variable / Function body section separator</i>
+implementation
+
+<i>; Definition of main function</i>
+define i32 %main() { <i>; i32()* </i>
+ <i>; Convert [13x i8 ]* to i8 *...</i>
+ %cast210 = <a
+ href="#i_getelementptr">getelementptr</a> [13 x i8 ]* %.LC0, i64 0, i64 0 <i>; i8 *</i>
+
+ <i>; Call puts function to write out the string to stdout...</i>
+ <a
+ href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
+ <a
+ href="#i_ret">ret</a> i32 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>
+
+<p>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 <a
+href="#linkage">linkage types</a>.</p>
+
+<p>Due to a limitation in the current LLVM assembly parser (it is limited by
+one-token lookahead), modules are split into two pieces by the "implementation"
+keyword. Global variable prototypes and definitions must occur before the
+keyword, and function definitions must occur after it. Function prototypes may
+occur either before or after it. In the future, the implementation keyword may
+become a noop, if the parser gets smarter.</p>
+
+</div>
<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="t_primitive">Primitive Types
-</b></font></td></tr></table><ul>
-
-The primitive types are the fundemental building blocks of the LLVM system. The
-current set of primitive types are as follows:<p>
-
-<table border=0 align=center><tr><td>
-
-<table border=1 cellspacing=0 cellpadding=4 align=center>
-<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>
-</table>
+<div class="doc_subsection">
+ <a name="linkage">Linkage Types</a>
+</div>
-</td><td valign=top>
+<div class="doc_text">
-<table border=1 cellspacing=0 cellpadding=4 align=center>
-<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>
-</table>
+<p>
+All Global Variables and Functions have one of the following types of linkage:
+</p>
-</td></tr></table><p>
+<dl>
+
+ <dt><tt><b><a name="linkage_internal">internal</a></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.
+ </dd>
+
+ <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
+
+ <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
+ the same name when linkage occurs. This is typically used to implement
+ inline functions, templates, or other code which must be generated in each
+ translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
+ allowed to be discarded.
+ </dd>
+
+ <dt><tt><b><a name="linkage_weak">weak</a></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 for globals that may be emitted in multiple translation units, but that
+ are not guaranteed to be emitted into every translation unit that uses them.
+ One example of this are common globals in C, such as "<tt>int X;</tt>" at
+ global scope.
+ </dd>
+
+ <dt><tt><b><a name="linkage_appending">appending</a></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.
+ </dd>
+
+ <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
+ <dd>The semantics of this linkage follow the ELF model: the symbol is weak
+ until linked, if not linked, the symbol becomes null instead of being an
+ undefined reference.
+ </dd>
+</dl>
+ <dt><tt><b><a name="linkage_external">externally visible</a></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.
+ </dd>
-<!-- _______________________________________________________________________ -->
-</ul><a name="t_classifications"><h4><hr size=0>Type Classifications</h4><ul>
+ <p>
+ The next two types of linkage are targeted for Microsoft Windows platform
+ only. They are designed to support importing (exporting) symbols from (to)
+ DLLs.
+ </p>
-These different primitive types fall into a few useful classifications:<p>
+ <dl>
+ <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
-<table border=1 cellspacing=0 cellpadding=4 align=center>
-<tr><td><a name="t_signed">signed</td> <td><tt>sbyte, short, int, long, float, double</tt></td></tr>
-<tr><td><a name="t_unsigned">unsigned</td><td><tt>ubyte, ushort, uint, ulong</tt></td></tr>
-<tr><td><a name="t_integral">integer</td><td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td></tr>
-<tr><td><a name="t_integral">integral</td><td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td></tr>
-<tr><td><a name="t_floating">floating point</td><td><tt>float, double</tt></td></tr>
-<tr><td><a name="t_firstclass">first class</td><td><tt>bool, ubyte, sbyte, ushort, short,<br> uint, int, ulong, long, float, double, <a href="#t_pointer">pointer</a></tt></td></tr>
-</table><p>
+ <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
+ or variable via a global pointer to a pointer that is set up by the DLL
+ exporting the symbol. On Microsoft Windows targets, the pointer name is
+ formed by combining <code>_imp__</code> and the function or variable name.
+ </dd>
+ <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
+ <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
+ pointer to a pointer in a DLL, so that it can be referenced with the
+ <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
+ name is formed by combining <code>_imp__</code> and the function or variable
+ name.
+ </dd>
+</dl>
+
+<p><a name="linkage_external"></a>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.</p>
+<p>It is illegal for a function <i>declaration</i>
+to have any linkage type other than "externally visible", <tt>dllimport</tt>,
+or <tt>extern_weak</tt>.</p>
+</div>
<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="t_derived">Derived Types
-</b></font></td></tr></table><ul>
+<div class="doc_subsection">
+ <a name="callingconv">Calling Conventions</a>
+</div>
+
+<div class="doc_text">
+
+<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
+and <a href="#i_invoke">invokes</a> can all have an optional calling convention
+specified for the call. The calling convention of any pair of dynamic
+caller/callee must match, or the behavior of the program is undefined. The
+following calling conventions are supported by LLVM, and more may be added in
+the future:</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>
+<dl>
+ <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
+
+ <dd>This calling convention (the default if no other calling convention is
+ specified) matches the target C calling conventions. This calling convention
+ supports varargs function calls and tolerates some mismatch in the declared
+ prototype and implemented declaration of the function (as does normal C).
+ </dd>
+
+ <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
+
+ <dd>This calling convention attempts to make calls as fast as possible
+ (e.g. by passing things in registers). This calling convention allows the
+ target to use whatever tricks it wants to produce fast code for the target,
+ without having to conform to an externally specified ABI. Implementations of
+ this convention should allow arbitrary tail call optimization to be supported.
+ This calling convention does not support varargs and requires the prototype of
+ all callees to exactly match the prototype of the function definition.
+ </dd>
+
+ <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
+
+ <dd>This calling convention attempts to make code in the caller as efficient
+ as possible under the assumption that the call is not commonly executed. As
+ such, these calls often preserve all registers so that the call does not break
+ any live ranges in the caller side. This calling convention does not support
+ varargs and requires the prototype of all callees to exactly match the
+ prototype of the function definition.
+ </dd>
+
+ <dt><b>"<tt>cc <<em>n</em>></tt>" - Numbered convention</b>:</dt>
+
+ <dd>Any calling convention may be specified by number, allowing
+ target-specific calling conventions to be used. Target specific calling
+ conventions start at 64.
+ </dd>
+</dl>
+<p>More calling conventions can be added/defined on an as-needed basis, to
+support pascal conventions or any other well-known target-independent
+convention.</p>
+</div>
-<!-- _______________________________________________________________________ -->
-</ul><a name="t_array"><h4><hr size=0>Array Type</h4><ul>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="visibility">Visibility Styles</a>
+</div>
-<h5>Overview:</h5>
+<div class="doc_text">
-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>
+<p>
+All Global Variables and Functions have one of the following visibility styles:
+</p>
-<h5>Syntax:</h5>
-<pre>
- [<# elements> x <elementtype>]
-</pre>
+<dl>
+ <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
-The number of elements is a constant integer value, elementtype may be any type
-with a size.<p>
+ <dd>On ELF, default visibility means that the declaration is visible to other
+ modules and, in shared libraries, means that the declared entity may be
+ overridden. On Darwin, default visibility means that the declaration is
+ visible to other modules. Default visibility corresponds to "external
+ linkage" in the language.
+ </dd>
-<h5>Examples:</h5>
-<ul>
- <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>
-</ul>
+ <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
-Here are some examples of multidimensional arrays:<p>
-<ul>
-<table border=0 cellpadding=0 cellspacing=0>
-<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>: 2x10 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>
-</table>
-</ul>
+ <dd>Two declarations of an object with hidden visibility refer to the same
+ object if they are in the same shared object. Usually, hidden visibility
+ indicates that the symbol will not be placed into the dynamic symbol table,
+ so no other module (executable or shared library) can reference it
+ directly.
+ </dd>
+</dl>
-<!-- _______________________________________________________________________ -->
-</ul><a name="t_function"><h4><hr size=0>Function Type</h4><ul>
+</div>
-<h5>Overview:</h5>
+<!-- ======================================================================= -->
+<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, may have
+an explicit section to be placed in, and may
+have an optional explicit alignment specified. A
+variable may be defined as a global "constant," which indicates that the
+contents of the variable will <b>never</b> be modified (enabling better
+optimization, allowing the global data to be placed in the read-only section of
+an executable, etc). Note that variables that need runtime initialization
+cannot be marked "constant" as there is a store to the variable.</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 when to build virtual function tables (which are structures of pointers to
-functions), for indirect function calls, and when defining a function.<p>
+<p>
+LLVM explicitly allows <em>declarations</em> of global variables to be marked
+constant, even if the final definition of the global is not. This capability
+can be used to enable slightly better optimization of the program, but requires
+the language definition to guarantee that optimizations based on the
+'constantness' are valid for the translation units that do not include the
+definition.
+</p>
+
+<p>As SSA values, global variables define pointer values that are in
+scope (i.e. they dominate) 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>
+
+<p>LLVM allows an explicit section to be specified for globals. If the target
+supports it, it will emit globals to the section specified.</p>
+
+<p>An explicit alignment may be specified for a global. If not present, or if
+the alignment is set to zero, the alignment of the global is set by the target
+to whatever it feels convenient. If an explicit alignment is specified, the
+global is forced to have at least that much alignment. All alignments must be
+a power of 2.</p>
+
+<p>For example, the following defines a global with an initializer, section,
+ and alignment:</p>
-<h5>Syntax:</h5>
<pre>
- <returntype> (<parameter list>)
+ %G = constant float 1.0, section "foo", align 4
</pre>
-Where '<tt><parameter list></tt>' is a comma seperated 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. Note
-that there currently is no way to define a function in LLVM that takes a
-variable number of arguments, but it is possible to <b>call</b> a function that
-is vararg.<p>
-
-<h5>Examples:</h5>
-<ul>
-<table border=0 cellpadding=0 cellspacing=0>
+</div>
-<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>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="functionstructure">Functions</a>
+</div>
+
+<div class="doc_text">
+
+<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
+an optional <a href="#linkage">linkage type</a>, an optional
+<a href="#visibility">visibility style</a>, an optional
+<a href="#callingconv">calling convention</a>, a return type, an optional
+<a href="#paramattrs">parameter attribute</a> for the return type, a function
+name, a (possibly empty) argument list (each with optional
+<a href="#paramattrs">parameter attributes</a>), an optional section, an
+optional alignment, an opening curly brace, a list of basic blocks, and a
+closing curly brace.
+
+LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
+optional <a href="#linkage">linkage type</a>, an optional
+<a href="#visibility">visibility style</a>, an optional
+<a href="#callingconv">calling convention</a>, a return type, an optional
+<a href="#paramattrs">parameter attribute</a> for the return type, a function
+name, a possibly empty list of arguments, and an optional alignment.</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 a 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>
-<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>
+<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 resolve references to each
+appropriately.</p>
-</table>
-</ul>
+<p>LLVM allows an explicit section to be specified for functions. If the target
+supports it, it will emit functions to the section specified.</p>
+<p>An explicit alignment may be specified for a function. If not present, or if
+the alignment is set to zero, the alignment of the function is set by the target
+to whatever it feels convenient. If an explicit alignment is specified, the
+function is forced to have at least that much alignment. All alignments must be
+a power of 2.</p>
+</div>
-<!-- _______________________________________________________________________ -->
-</ul><a name="t_struct"><h4><hr size=0>Structure Type</h4><ul>
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
+<div class="doc_text">
+ <p>The return type and each parameter of a function type may have a set of
+ <i>parameter attributes</i> associated with them. Parameter attributes are
+ used to communicate additional information about the result or parameters of
+ a function. Parameter attributes are considered to be part of the function
+ type so two functions types that differ only by the parameter attributes
+ are different function types.</p>
+
+ <p>Parameter attributes are simple keywords that follow the type specified. If
+ multiple parameter attributes are needed, they are space separated. For
+ example:</p><pre>
+ %someFunc = i16 (i8 sext %someParam) zext
+ %someFunc = i16 (i8 zext %someParam) zext</pre>
+ <p>Note that the two function types above are unique because the parameter has
+ a different attribute (sext in the first one, zext in the second). Also note
+ that the attribute for the function result (zext) comes immediately after the
+ argument list.</p>
+
+ <p>Currently, only the following parameter attributes are defined:</p>
+ <dl>
+ <dt><tt>zext</tt></dt>
+ <dd>This indicates that the parameter should be zero extended just before
+ a call to this function.</dd>
+ <dt><tt>sext</tt></dt>
+ <dd>This indicates that the parameter should be sign extended just before
+ a call to this function.</dd>
+ <dt><tt>inreg</tt></dt>
+ <dd>This indicates that the parameter should be placed in register (if
+ possible) during assembling function call. Support for this attribute is
+ target-specific</dd>
+ <dt><tt>sret</tt></dt>
+ <dd>This indicates that the parameter specifies the address of a structure
+ that is the return value of the function in the source program.</dd>
+ <dt><tt>noreturn</tt></dt>
+ <dd>This function attribute indicates that the function never returns. This
+ indicates to LLVM that every call to this function should be treated as if
+ an <tt>unreachable</tt> instruction immediately followed the call.</dd>
+ <dt><tt>nounwind</tt></dt>
+ <dd>This function attribute indicates that the function type does not use
+ the unwind instruction and does not allow stack unwinding to propagate
+ through it.</dd>
+ </dl>
+
+</div>
-<h5>Overview:</h5>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="moduleasm">Module-Level Inline Assembly</a>
+</div>
-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>
+<div class="doc_text">
+<p>
+Modules may contain "module-level inline asm" blocks, which corresponds to the
+GCC "file scope inline asm" blocks. These blocks are internally concatenated by
+LLVM and treated as a single unit, but may be separated in the .ll file if
+desired. The syntax is very simple:
+</p>
+
+<div class="doc_code"><pre>
+ module asm "inline asm code goes here"
+ module asm "more can go here"
+</pre></div>
+
+<p>The strings can contain any character by escaping non-printable characters.
+ The escape sequence used is simply "\xx" where "xx" is the two digit hex code
+ for the number.
+</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>
+<p>
+ The inline asm code is simply printed to the machine code .s file when
+ assembly code is generated.
+</p>
+</div>
-<h5>Syntax:</h5>
-<pre>
- { <type list> }
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="datalayout">Data Layout</a>
+</div>
+
+<div class="doc_text">
+<p>A module may specify a target specific data layout string that specifies how
+data is to be laid out in memory. The syntax for the data layout is simply:<br/>
+<pre> target datalayout = "<i>layout specification</i>"
</pre>
+The <i>layout specification</i> consists of a list of specifications separated
+by the minus sign character ('-'). Each specification starts with a letter
+and may include other information after the letter to define some aspect of the
+data layout. The specifications accepted are as follows: </p>
+<dl>
+ <dt><tt>E</tt></dt>
+ <dd>Specifies that the target lays out data in big-endian form. That is, the
+ bits with the most significance have the lowest address location.</dd>
+ <dt><tt>e</tt></dt>
+ <dd>Specifies that hte target lays out data in little-endian form. That is,
+ the bits with the least significance have the lowest address location.</dd>
+ <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
+ <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
+ <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
+ alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
+ too.</dd>
+ <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
+ <dd>This specifies the alignment for an integer type of a given bit
+ <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
+ <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
+ <dd>This specifies the alignment for a vector type of a given bit
+ <i>size</i>.</dd>
+ <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
+ <dd>This specifies the alignment for a floating point type of a given bit
+ <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
+ (double).</dd>
+ <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
+ <dd>This specifies the alignment for an aggregate type of a given bit
+ <i>size</i>.</dd>
+</dl>
+<p>When constructing the data layout for a given target, LLVM starts with a
+default set of specifications which are then (possibly) overriden by the
+specifications in the <tt>datalayout</tt> keyword. The default specifications
+are given in this list:</p>
+<ul>
+ <li><tt>E</tt> - big endian</li>
+ <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
+ <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
+ <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
+ <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
+ <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
+ <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
+ alignment of 64-bits</li>
+ <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
+ <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
+ <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
+ <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
+ <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
+</ul>
+<p>When llvm is determining the alignment for a given type, it uses the
+following rules:
+<ol>
+ <li>If the type sought is an exact match for one of the specifications, that
+ specification is used.</li>
+ <li>If no match is found, and the type sought is an integer type, then the
+ smallest integer type that is larger than the bitwidth of the sought type is
+ used. If none of the specifications are larger than the bitwidth then the the
+ largest integer type is used. For example, given the default specifications
+ above, the i7 type will use the alignment of i8 (next largest) while both
+ i65 and i256 will use the alignment of i64 (largest specified).</li>
+ <li>If no match is found, and the type sought is a vector type, then the
+ largest vector type that is smaller than the sought vector type will be used
+ as a fall back. This happens because <128 x double> can be implemented in
+ terms of 64 <2 x double>, for example.</li>
+</ol>
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section"> <a name="typesystem">Type System</a> </div>
+<!-- *********************************************************************** -->
+<div class="doc_text">
-<h5>Examples:</h5>
-<table border=0 cellpadding=0 cellspacing=0>
+<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>
-<tr><td><tt>{ int, int, int }</tt></td><td>: a triple of three <tt>int</tt>
-values</td></tr>
+</div>
-<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>
+<!-- ======================================================================= -->
+<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
+<div class="doc_text">
+<p>The primitive types are the fundamental building blocks of the LLVM
+system. The current set of primitive types is as follows:</p>
+
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <table>
+ <tbody>
+ <tr><th>Type</th><th>Description</th></tr>
+ <tr><td><tt>void</tt></td><td>No value</td></tr>
+ <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
+ <tr><td><tt>i32</tt></td><td>32-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 class="right">
+ <table>
+ <tbody>
+ <tr><th>Type</th><th>Description</th></tr>
+ <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
+ <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
+ <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
+ <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
+ </tbody>
+ </table>
+ </td>
+ </tr>
+</table>
+</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>
+
+<table border="1" cellspacing="0" cellpadding="4">
+ <tbody>
+ <tr><th>Classification</th><th>Types</th></tr>
+ <tr>
+ <td><a name="t_integer">integer</a></td>
+ <td><tt>i1, i8, i16, i32, i64</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>i1, i8, i16, i32, i64, float, double, <br/>
+ <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
+ </td>
+ </tr>
+ </tbody>
</table>
+<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>
<!-- _______________________________________________________________________ -->
-</ul><a name="t_pointer"><h4><hr size=0>Pointer Type</h4><ul>
+<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
+
+<div class="doc_text">
<h5>Overview:</h5>
-As in many languages, the pointer type represents a pointer or reference to
-another object, which must live in memory.<p>
+<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>
- <type> *
+ [<# elements> x <elementtype>]
</pre>
-<h5>Examples:</h5>
+<p>The number of elements is a constant integer value; elementtype may
+be any type with a size.</p>
-<table border=0 cellpadding=0 cellspacing=0>
+<h5>Examples:</h5>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt>[40 x i32 ]</tt><br/>
+ <tt>[41 x i32 ]</tt><br/>
+ <tt>[40 x i8]</tt><br/>
+ </td>
+ <td class="left">
+ Array of 40 32-bit integer values.<br/>
+ Array of 41 32-bit integer values.<br/>
+ Array of 40 8-bit integer values.<br/>
+ </td>
+ </tr>
+</table>
+<p>Here are some examples of multidimensional arrays:</p>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt>[3 x [4 x i32]]</tt><br/>
+ <tt>[12 x [10 x float]]</tt><br/>
+ <tt>[2 x [3 x [4 x i16]]]</tt><br/>
+ </td>
+ <td class="left">
+ 3x4 array of 32-bit integer values.<br/>
+ 12x10 array of single precision floating point values.<br/>
+ 2x3x4 array of 16-bit integer values.<br/>
+ </td>
+ </tr>
+</table>
-<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>
+<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
+length array. Normally, accesses past the end of an array are undefined in
+LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
+As a special case, however, zero length arrays are recognized to be variable
+length. This allows implementation of 'pascal style arrays' with the LLVM
+type "{ i32, [0 x float]}", for example.</p>
-<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>
+</div>
-</table>
+<!-- _______________________________________________________________________ -->
+<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> <returntype> (<parameter list>)<br></pre>
+<p>...where '<tt><parameter list></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>
+<table class="layout">
+ <tr class="layout">
+ <td class="left"><tt>i32 (i32)</tt></td>
+ <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
+ </td>
+ </tr><tr class="layout">
+ <td class="left"><tt>float (i16 sext, i32 *) *
+ </tt></td>
+ <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
+ an <tt>i16</tt> that should be sign extended and a
+ <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
+ <tt>float</tt>.
+ </td>
+ </tr><tr class="layout">
+ <td class="left"><tt>i32 (i8*, ...)</tt></td>
+ <td class="left">A vararg function that takes at least one
+ <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
+ which returns an integer. This is the signature for <tt>printf</tt> in
+ LLVM.
+ </td>
+ </tr>
+</table>
+</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> { <type list> }<br></pre>
+<h5>Examples:</h5>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt>{ i32, i32, i32 }</tt><br/>
+ <tt>{ float, i32 (i32) * }</tt><br/>
+ </td>
+ <td class="left">
+ a triple of three <tt>i32</tt> values<br/>
+ 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>i32</tt>, returning an <tt>i32</tt>.<br/>
+ </td>
+ </tr>
+</table>
+</div>
<!-- _______________________________________________________________________ -->
-<!--
-</ul><a name="t_packed"><h4><hr size=0>Packed Type</h4><ul>
+<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
+</div>
+<div class="doc_text">
+<h5>Overview:</h5>
+<p>The packed structure type is used to represent a collection of data members
+together in memory. There is no padding between fields. Further, the alignment
+of a packed structure is 1 byte. The elements of a packed 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> < { <type list> } > <br></pre>
+<h5>Examples:</h5>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt> < { i32, i32, i32 } > </tt><br/>
+ <tt> < { float, i32 (i32) * } > </tt><br/>
+ </td>
+ <td class="left">
+ a triple of three <tt>i32</tt> values<br/>
+ 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>i32</tt>, returning an <tt>i32</tt>.<br/>
+ </td>
+ </tr>
+</table>
+</div>
-Mention/decide that packed types work with saturation or not. Maybe have a packed+saturated type in addition to just a packed type.<p>
+<!-- _______________________________________________________________________ -->
+<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> <type> *<br></pre>
+<h5>Examples:</h5>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt>[4x i32]*</tt><br/>
+ <tt>i32 (i32 *) *</tt><br/>
+ </td>
+ <td class="left">
+ A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
+ four <tt>i32</tt> values<br/>
+ A <a href="#t_pointer">pointer</a> to a <a
+ href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
+ <tt>i32</tt>.<br/>
+ </td>
+ </tr>
+</table>
+</div>
-Packed types should be 'nonsaturated' because standard data types are not saturated. Maybe have a saturated packed type?<p>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
+<div class="doc_text">
--->
+<h5>Overview:</h5>
+<p>A vector type is a simple derived type that represents a vector
+of elements. Vector types are used when multiple primitive data
+are operated in parallel using a single instruction (SIMD).
+A vector type requires a size (number of
+elements) and an underlying primitive data type. Vectors must have a power
+of two length (1, 2, 4, 8, 16 ...). Vector types are
+considered <a href="#t_firstclass">first class</a>.</p>
-<!-- *********************************************************************** -->
-</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="highlevel">High Level Structure
-</b></font></td></tr></table><ul>
-<!-- *********************************************************************** -->
+<h5>Syntax:</h5>
+<pre>
+ < <# elements> x <elementtype> >
+</pre>
-<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="modulestructure">Module Structure
-</b></font></td></tr></table><ul>
+<p>The number of elements is a constant integer value; elementtype may
+be any integer or floating point type.</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>
+<h5>Examples:</h5>
-<pre>
-<i>; Declare the string constant as a global constant...</i>
-<a href="#identifiers">%.LC0</a> = <a href="#linkage_decl">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>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt><4 x i32></tt><br/>
+ <tt><8 x float></tt><br/>
+ <tt><2 x i64></tt><br/>
+ </td>
+ <td class="left">
+ Vector of 4 32-bit integer values.<br/>
+ Vector of 8 floating-point values.<br/>
+ Vector of 2 64-bit integer values.<br/>
+ </td>
+ </tr>
+</table>
+</div>
-<i>; Forward declaration of puts</i>
-<a href="#functionstructure">declare</a> int "puts"(sbyte*) <i>; int(sbyte*)* </i>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
+<div class="doc_text">
-<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, uint 0, uint 0 <i>; sbyte*</i>
+<h5>Overview:</h5>
- <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
-}
-</pre>
+<p>Opaque types are used to represent unknown types in the system. This
+corresponds (for example) to the C notion of a foward declared structure type.
+In LLVM, opaque types can eventually be resolved to any type (not just a
+structure type).</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>
+<h5>Syntax:</h5>
-<a name="linkage_decl">
-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 can be either "internal" or externally accessible
-(which corresponds to the static keyword in C, when used at global scope).<p>
+<pre>
+ opaque
+</pre>
-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 "<tt>internal</tt>"
-declarations), they are accessible outside of the current module. It is illegal
-for a function declaration to be "<tt>internal</tt>".<p>
+<h5>Examples:</h5>
+<table class="layout">
+ <tr class="layout">
+ <td class="left">
+ <tt>opaque</tt>
+ </td>
+ <td class="left">
+ An opaque type.<br/>
+ </td>
+ </tr>
+</table>
+</div>
-<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="globalvars">Global Variables
-</b></font></td></tr></table><ul>
-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>
+<!-- *********************************************************************** -->
+<div class="doc_section"> <a name="constants">Constants</a> </div>
+<!-- *********************************************************************** -->
-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 class="doc_text">
+<p>LLVM has several different basic types of constants. This section describes
+them all and their syntax.</p>
+</div>
<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="functionstructure">Function Structure
-</b></font></td></tr></table><ul>
-
-LLVM functions 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>
-
-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>
-
-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).<p>
+<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
+<div class="doc_text">
-<!-- *********************************************************************** -->
-</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="instref">Instruction Reference
-</b></font></td></tr></table><ul>
-<!-- *********************************************************************** -->
-
-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>
+<dl>
+ <dt><b>Boolean constants</b></dt>
+ <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
+ constants of the <tt><a href="#t_primitive">i1</a></tt> type.
+ </dd>
-<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="terminators">Terminator Instructions
-</b></font></td></tr></table><ul>
+ <dt><b>Integer constants</b></dt>
-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>
+ <dd>Standard integers (such as '4') are constants of the <a
+ href="#t_integer">integer</a> type. Negative numbers may be used with
+ integer types.
+ </dd>
-There are four 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, and the '<a
-href="#i_invoke"><tt>invoke</tt></a>' instruction.<p>
+ <dt><b>Floating point constants</b></dt>
+ <dd>Floating point constants use standard decimal notation (e.g. 123.421),
+ exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
+ notation (see below). Floating point constants must have a <a
+ href="#t_floating">floating point</a> type. </dd>
-<!-- _______________________________________________________________________ -->
-</ul><a name="i_ret"><h4><hr size=0>'<tt>ret</tt>' Instruction</h4><ul>
+ <dt><b>Null pointer constants</b></dt>
-<h5>Syntax:</h5>
-<pre>
- ret <type> <value> <i>; Return a value from a non-void function</i>
- ret void <i>; Return from void function</i>
-</pre>
+ <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
+ and must be of <a href="#t_pointer">pointer type</a>.</dd>
-<h5>Overview:</h5>
+</dl>
-The '<tt>ret</tt>' instruction is used to return control flow (and a value) from
-a function, back to the caller.<p>
+<p>The one non-intuitive notation for constants is the optional hexadecimal 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>'. The only time hexadecimal floating point constants are required
+(and the only time that they are generated by the disassembler) is when a
+floating point constant must be emitted but it cannot be represented as a
+decimal floating point number. For example, NaN's, infinities, and other
+special values are represented in their IEEE hexadecimal format so that
+assembly and disassembly do not cause any bits to change in the constants.</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>
+</div>
-<h5>Arguments:</h5>
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
+</div>
-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>
+<div class="doc_text">
+<p>Aggregate constants arise from aggregation of simple constants
+and smaller aggregate constants.</p>
-<h5>Semantics:</h5>
+<dl>
+ <dt><b>Structure constants</b></dt>
+
+ <dd>Structure constants are represented with notation similar to structure
+ type definitions (a comma separated list of elements, surrounded by braces
+ (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
+ where "<tt>%G</tt>" is declared as "<tt>%G = external global i32</tt>". Structure constants
+ must have <a href="#t_struct">structure type</a>, and the number and
+ types of elements must match those specified by the type.
+ </dd>
+
+ <dt><b>Array constants</b></dt>
+
+ <dd>Array constants are represented with notation similar to array type
+ definitions (a comma separated list of elements, surrounded by square brackets
+ (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
+ constants must have <a href="#t_array">array type</a>, and the number and
+ types of elements must match those specified by the type.
+ </dd>
+
+ <dt><b>Vector constants</b></dt>
+
+ <dd>Vector constants are represented with notation similar to vector type
+ definitions (a comma separated list of elements, surrounded by
+ less-than/greater-than's (<tt><></tt>)). For example: "<tt>< i32 42,
+ i32 11, i32 74, i32 100 ></tt>". VEctor constants must have <a
+ href="#t_vector">vector type</a>, and the number and types of elements must
+ match those specified by the type.
+ </dd>
+
+ <dt><b>Zero initialization</b></dt>
+
+ <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
+ value to zero of <em>any</em> type, including scalar and aggregate types.
+ This is often used to avoid having to print large zero initializers (e.g. for
+ large arrays) and is always exactly equivalent to using explicit zero
+ initializers.
+ </dd>
+</dl>
-When the '<tt>ret</tt>' instruction is executed, control flow returns back to
-the calling function's context. If the instruction returns a value, that value
-shall be propogated into the calling function's data space.<p>
+</div>
-<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 class="doc_subsection">
+ <a name="globalconstants">Global Variable and Function Addresses</a>
+</div>
+<div class="doc_text">
-<!-- _______________________________________________________________________ -->
-</ul><a name="i_br"><h4><hr size=0>'<tt>br</tt>' Instruction</h4><ul>
+<p>The addresses of <a href="#globalvars">global variables</a> and <a
+href="#functionstructure">functions</a> are always implicitly valid (link-time)
+constants. These constants are explicitly referenced when the <a
+href="#identifiers">identifier for the global</a> is used and always have <a
+href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
+file:</p>
-<h5>Syntax:</h5>
<pre>
- br bool <cond>, label <iftrue>, label <iffalse>
- br label <dest> <i>; Unconditional branch</i>
+ %X = global i32 17
+ %Y = global i32 42
+ %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
</pre>
-<h5>Overview:</h5>
-
-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>
+</div>
-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>
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
+<div class="doc_text">
+ <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
+ no specific value. Undefined values may be of any type and be used anywhere
+ a constant is permitted.</p>
-<h5>Semantics:</h5>
+ <p>Undefined values indicate to the compiler that the program is well defined
+ no matter what value is used, giving the compiler more freedom to optimize.
+ </p>
+</div>
-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>
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
+</div>
-<h5>Example:</h5>
-<pre>
-Test:
- %cond = <a href="#i_setcc">seteq</a> int %a, %b
- br bool %cond, label %IfEqual, label %IfUnequal
-IfEqual:
- <a href="#i_ret">ret</a> int 1
-IfUnequal:
- <a href="#i_ret">ret</a> int 0
-</pre>
+<div class="doc_text">
+<p>Constant expressions are used to allow expressions involving other constants
+to be used as constants. Constant expressions may be of any <a
+href="#t_firstclass">first class</a> type and may involve any LLVM operation
+that does not have side effects (e.g. load and call are not supported). The
+following is the syntax for constant expressions:</p>
-<!-- _______________________________________________________________________ -->
-</ul><a name="i_switch"><h4><hr size=0>'<tt>switch</tt>' Instruction</h4><ul>
+<dl>
+ <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
+ <dd>Truncate a constant to another type. The bit size of CST must be larger
+ than the bit size of TYPE. Both types must be integers.</dd>
-<h5>Syntax:</h5>
-<pre>
- <i>; Definitions for lookup indirect branch</i>
- %switchtype = type [<anysize> x { uint, label }]
+ <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
+ <dd>Zero extend a constant to another type. The bit size of CST must be
+ smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
- <i>; Lookup indirect branch</i>
- switch uint <value>, label <defaultdest>, %switchtype <switchtable>
+ <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
+ <dd>Sign extend a constant to another type. The bit size of CST must be
+ smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
- <i>; Indexed indirect branch</i>
- switch uint <idxvalue>, label <defaultdest>, [<anysize> x label] <desttable>
-</pre>
+ <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
+ <dd>Truncate a floating point constant to another floating point type. The
+ size of CST must be larger than the size of TYPE. Both types must be
+ floating point.</dd>
-<h5>Overview:</h5>
+ <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
+ <dd>Floating point extend a constant to another type. The size of CST must be
+ smaller or equal to the size of TYPE. Both types must be floating point.</dd>
-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>
+ <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
+ <dd>Convert a floating point constant to the corresponding unsigned integer
+ constant. TYPE must be an integer type. CST must be floating point. If the
+ value won't fit in the integer type, the results are undefined.</dd>
-The '<tt>switch</tt>' statement supports two different styles of indirect
-branching: lookup branching and indexed branching. Lookup branching is
-generally useful if the values to switch on are spread far appart, where index
-branching is useful if the values to switch on are generally dense.<p>
+ <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
+ <dd>Convert a floating point constant to the corresponding signed integer
+ constant. TYPE must be an integer type. CST must be floating point. If the
+ value won't fit in the integer type, the results are undefined.</dd>
-The two different forms of the '<tt>switch</tt>' statement are simple hints to
-the underlying implementation. For example, the compiler may choose to
-implement a small indirect branch table as a series of predicated comparisons:
-if it is faster for the target architecture.<p>
+ <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
+ <dd>Convert an unsigned integer constant to the corresponding floating point
+ constant. TYPE must be floating point. CST must be of integer type. If the
+ value won't fit in the floating point type, the results are undefined.</dd>
-<h5>Arguments:</h5>
+ <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
+ <dd>Convert a signed integer constant to the corresponding floating point
+ constant. TYPE must be floating point. CST must be of integer type. If the
+ value won't fit in the floating point type, the results are undefined.</dd>
-The lookup form of 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. The sized array must be a constant value.<p>
+ <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
+ <dd>Convert a pointer typed constant to the corresponding integer constant
+ TYPE must be an integer type. CST must be of pointer type. The CST value is
+ zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
-The indexed form of the '<tt>switch</tt>' instruction uses three parameters: an
-'<tt>uint</tt>' index value, a default '<tt>label</tt>' and a sized array of
-'<tt>label</tt>'s. The '<tt>dests</tt>' array must be a constant array.
+ <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
+ <dd>Convert a integer constant to a pointer constant. TYPE must be a
+ pointer type. CST must be of integer type. The CST value is zero extended,
+ truncated, or unchanged to make it fit in a pointer size. This one is
+ <i>really</i> dangerous!</dd>
-<h5>Semantics:</h5>
+ <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
+ <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
+ identical (same number of bits). The conversion is done as if the CST value
+ was stored to memory and read back as TYPE. In other words, no bits change
+ with this operator, just the type. This can be used for conversion of
+ vector types to any other type, as long as they have the same bit width. For
+ pointers it is only valid to cast to another pointer type.
+ </dd>
-The lookup style switch statement 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. <p>
+ <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
-The index branch form simply looks up a label element directly in a table and
-branches to it.<p>
+ <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
+ constants. As with the <a href="#i_getelementptr">getelementptr</a>
+ instruction, the index list may have zero or more indexes, which are required
+ to make sense for the type of "CSTPTR".</dd>
-In either case, the compiler knows the static size of the array, because it is
-provided as part of the constant values type.<p>
+ <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
-<h5>Example:</h5>
-<pre>
- <i>; Emulate a conditional br instruction</i>
- %Val = <a href="#i_cast">cast</a> bool %value to uint
- switch uint %Val, label %truedest, [1 x label] [label %falsedest ]
+ <dd>Perform the <a href="#i_select">select operation</a> on
+ constants.</dd>
- <i>; Emulate an unconditional br instruction</i>
- switch uint 0, label %dest, [ 0 x label] [ ]
+ <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
+ <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
- <i>; Implement a jump table:</i>
- switch uint %val, label %otherwise, [3 x label] [ label %onzero,
- label %onone,
- label %ontwo ]
+ <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
+ <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
-</pre>
+ <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
+ <dd>Perform the <a href="#i_extractelement">extractelement
+ operation</a> on constants.
+ <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
-<!-- _______________________________________________________________________ -->
-</ul><a name="i_invoke"><h4><hr size=0>'<tt>invoke</tt>' Instruction</h4><ul>
+ <dd>Perform the <a href="#i_insertelement">insertelement
+ operation</a> on constants.</dd>
-<h5>Syntax:</h5>
-<pre>
- <result> = invoke <ptr to function ty> %<function ptr val>(<function args>)
- to label <normal label> except label <exception label>
-</pre>
-<h5>Overview:</h5>
+ <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
-The '<tt>invoke</tt>' instruction is used to cause control flow to transfer to a
-specified function, with the possibility of control flow transfer to either the
-'<tt>normal label</tt>' label or the '<tt>exception label</tt>'. The '<tt><a
-href="#i_call">call</a></tt>' instruction is closely related, but guarantees
-that control flow either never returns from the called function, or that it
-returns to the instruction following the '<tt><a href="#i_call">call</a></tt>'
-instruction.<p>
+ <dd>Perform the <a href="#i_shufflevector">shufflevector
+ operation</a> on constants.</dd>
-<h5>Arguments:</h5>
+ <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
-This instruction requires several arguments:<p>
-<ol>
+ <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
+ be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
+ binary</a> operations. The constraints on operands are the same as those for
+ the corresponding instruction (e.g. no bitwise operations on floating point
+ values are allowed).</dd>
+</dl>
+</div>
-<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.<p>
+<!-- *********************************************************************** -->
+<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
+<!-- *********************************************************************** -->
-<li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
-function to be invoked.
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+<a name="inlineasm">Inline Assembler Expressions</a>
+</div>
-<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.
+<div class="doc_text">
-<li>'<tt>normal label</tt>': the label reached when the called function executes
-a '<tt><a href="#i_ret">ret</a></tt>' instruction.
+<p>
+LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
+Module-Level Inline Assembly</a>) through the use of a special value. This
+value represents the inline assembler as a string (containing the instructions
+to emit), a list of operand constraints (stored as a string), and a flag that
+indicates whether or not the inline asm expression has side effects. An example
+inline assembler expression is:
+</p>
-<li>'<tt>exception label</tt>': the label reached when an exception is thrown.
-</ol>
+<pre>
+ i32 (i32) asm "bswap $0", "=r,r"
+</pre>
-<h5>Semantics:</h5>
+<p>
+Inline assembler expressions may <b>only</b> be used as the callee operand of
+a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
+</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 associates a label with the function invocation that may
-be accessed via the runtime library provided by the execution environment. 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>
+<pre>
+ %X = call i32 asm "<a href="#i_bswap">bswap</a> $0", "=r,r"(i32 %Y)
+</pre>
-<!-- For a more comprehensive explanation of how this instruction is used, look in the llvm/docs/2001-05-18-ExceptionHandling.txt document.<p> -->
+<p>
+Inline asms with side effects not visible in the constraint list must be marked
+as having side effects. This is done through the use of the
+'<tt>sideeffect</tt>' keyword, like so:
+</p>
-<h5>Example:</h5>
<pre>
- %retval = invoke int %Test(int 15)
- to label %Continue except label %TestCleanup <i>; {int}:retval set</i>
+ call void asm sideeffect "eieio", ""()
</pre>
+<p>TODO: The format of the asm and constraints string still need to be
+documented here. Constraints on what can be done (e.g. duplication, moving, etc
+need to be documented).
+</p>
+</div>
-<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="binaryops">Binary Operations
-</b></font></td></tr></table><ul>
+<!-- *********************************************************************** -->
+<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
+<!-- *********************************************************************** -->
-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 neccesarily the same type as its
-operands.<p>
+<div class="doc_text">
-There are several different binary operators:<p>
+<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="#bitwiseops">bitwise binary instructions</a>, <a
+ href="#memoryops">memory instructions</a>, and <a href="#otherops">other
+instructions</a>.</p>
+</div>
-<!-- _______________________________________________________________________ -->
-</ul><a name="i_add"><h4><hr size=0>'<tt>add</tt>' Instruction</h4><ul>
+<!-- ======================================================================= -->
+<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 six 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, the '<a
+ href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
+ href="#i_unreachable"><tt>unreachable</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>
- <result> = add <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+<pre> ret <type> <value> <i>; Return a value from a non-void function</i>
+ ret void <i>; Return from void function</i>
</pre>
-
<h5>Overview:</h5>
-The '<tt>add</tt>' instruction returns the sum of its two operands.<p>
+<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>' instruction: 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 of the "normal" 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 i32 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 i1 <cond>, label <iftrue>, label <iffalse><br> br label <dest> <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>i1</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>i1</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_icmp">icmp</a> eq, i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
+ href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 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 <intty> <value>, label <defaultdest> [ <intty> <val>, label <dest> ... ]
+</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: an integer
+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. The
+table is not allowed to contain duplicate constant entries.</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, control flow is
+transfered to the corresponding destination; otherwise, control flow is
+transfered to the default destination.</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 in different
+ways. For example, it could be 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_zext">zext</a> i1 %value to i32
+ switch i32 %Val, label %truedest [i32 0, label %falsedest ]
+
+ <i>; Emulate an unconditional br instruction</i>
+ switch i32 0, label %dest [ ]
+
+ <i>; Implement a jump table:</i>
+ switch i32 %val, label %otherwise [ i32 0, label %onzero
+ i32 1, label %onone
+ i32 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>
+ <result> = invoke [<a href="#callingconv">cconv</a>] <ptr to function ty> %<function ptr val>(<function args>)
+ to label <normal label> unwind label <exception label>
+</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>' label or the
+'<tt>exception</tt>' label. 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 "exception" label.</p>
+
+<h5>Arguments:</h5>
+
+<p>This instruction requires several arguments:</p>
+
+<ol>
+ <li>
+ The optional "cconv" marker indicates which <a href="callingconv">calling
+ convention</a> the call should use. If none is specified, the call defaults
+ to using C calling conventions.
+ </li>
+ <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 i32 %Test(i32 15) to label %Continue
+ unwind label %TestCleanup <i>; {i32}:retval set</i>
+ %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
+ unwind label %TestCleanup <i>; {i32}: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
+</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_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
+Instruction</a> </div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ unreachable
+</pre>
+
+<h5>Overview:</h5>
+
+<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
+instruction is used to inform the optimizer that a particular portion of the
+code is not reachable. This can be used to indicate that the code after a
+no-return function cannot be reached, and other facts.</p>
+
+<h5>Semantics:</h5>
+
+<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</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 operands might represent
+multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
+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> <result> = add <ty> <var1>, <var2> <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.
+ This instruction can also take <a href="#t_vector">vector</a> versions of the 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> <result> = add i32 4, %var <i>; yields {i32}: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> <result> = sub <ty> <var1>, <var2> <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.
+This instruction can also take <a href="#t_vector">vector</a> versions of the 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> <result> = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
+ <result> = sub i32 0, %val <i>; yields {i32}: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> <result> = mul <ty> <var1>, <var2> <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.
+This instruction can also take <a href="#t_vector">vector</a> versions of the 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>Because the operands are the same width, the result of an integer
+multiplication is the same whether the operands should be deemed unsigned or
+signed.</p>
+<h5>Example:</h5>
+<pre> <result> = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
+</a></div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = udiv <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
+operands.</p>
+<h5>Arguments:</h5>
+<p>The two arguments to the '<tt>udiv</tt>' instruction must be
+<a href="#t_integer">integer</a> values. Both arguments must have identical
+types. This instruction can also take <a href="#t_vector">vector</a> versions
+of the values in which case the elements must be integers.</p>
+<h5>Semantics:</h5>
+<p>The value produced is the unsigned integer quotient of the two operands. This
+instruction always performs an unsigned division operation, regardless of
+whether the arguments are unsigned or not.</p>
+<h5>Example:</h5>
+<pre> <result> = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
+</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = sdiv <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
+operands.</p>
+<h5>Arguments:</h5>
+<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
+<a href="#t_integer">integer</a> values. Both arguments must have identical
+types. This instruction can also take <a href="#t_vector">vector</a> versions
+of the values in which case the elements must be integers.</p>
+<h5>Semantics:</h5>
+<p>The value produced is the signed integer quotient of the two operands. This
+instruction always performs a signed division operation, regardless of whether
+the arguments are signed or not.</p>
+<h5>Example:</h5>
+<pre> <result> = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = fdiv <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>fdiv</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
+<a href="#t_floating">floating point</a> values. Both arguments must have
+identical types. This instruction can also take <a href="#t_vector">vector</a>
+versions of the values in which case the elements must be floating point.</p>
+<h5>Semantics:</h5>
+<p>The value produced is the floating point quotient of the two operands.</p>
+<h5>Example:</h5>
+<pre> <result> = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = urem <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>urem</tt>' instruction returns the remainder from the
+unsigned division of its two arguments.</p>
+<h5>Arguments:</h5>
+<p>The two arguments to the '<tt>urem</tt>' instruction must be
+<a href="#t_integer">integer</a> values. Both arguments must have identical
+types.</p>
+<h5>Semantics:</h5>
+<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
+This instruction always performs an unsigned division to get the remainder,
+regardless of whether the arguments are unsigned or not.</p>
+<h5>Example:</h5>
+<pre> <result> = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
+</pre>
+
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = srem <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>srem</tt>' instruction returns the remainder from the
+signed division of its two operands.</p>
+<h5>Arguments:</h5>
+<p>The two arguments to the '<tt>srem</tt>' instruction must be
+<a href="#t_integer">integer</a> values. Both arguments must have identical
+types.</p>
+<h5>Semantics:</h5>
+<p>This instruction returns the <i>remainder</i> of a division (where the result
+has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
+operator (where the result has the same sign as the divisor, <tt>var2</tt>) 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>. For a table of how this is implemented in various languages,
+please see <a href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">
+Wikipedia: modulo operation</a>.</p>
+<h5>Example:</h5>
+<pre> <result> = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
+</pre>
+
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = frem <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>frem</tt>' instruction returns the remainder from the
+division of its two operands.</p>
+<h5>Arguments:</h5>
+<p>The two arguments to the '<tt>frem</tt>' instruction must be
+<a href="#t_floating">floating point</a> values. Both arguments must have
+identical types.</p>
+<h5>Semantics:</h5>
+<p>This instruction returns the <i>remainder</i> of a division.</p>
+<h5>Example:</h5>
+<pre> <result> = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</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_shl">'<tt>shl</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = shl <ty> <var1>, <var2> <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>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
+ href="#t_integer">integer</a> type.</p>
+<h5>Semantics:</h5>
+<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
+<h5>Example:</h5><pre>
+ <result> = shl i32 4, %var <i>; yields {i32}: 4 << %var</i>
+ <result> = shl i32 4, 2 <i>; yields {i32}: 16</i>
+ <result> = shl i32 1, 10 <i>; yields {i32}: 1024</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = lshr <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
+operand shifted to the right a specified number of bits.</p>
+
+<h5>Arguments:</h5>
+<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
+<a href="#t_integer">integer</a> type.</p>
+
+<h5>Semantics:</h5>
+<p>This instruction always performs a logical shift right operation. The most
+significant bits of the result will be filled with zero bits after the
+shift.</p>
+
+<h5>Example:</h5>
+<pre>
+ <result> = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
+ <result> = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
+ <result> = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
+ <result> = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre> <result> = ashr <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
+operand shifted to the right a specified number of bits.</p>
+
+<h5>Arguments:</h5>
+<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
+<a href="#t_integer">integer</a> type.</p>
+
+<h5>Semantics:</h5>
+<p>This instruction always performs an arithmetic shift right operation,
+The most significant bits of the result will be filled with the sign bit
+of <tt>var1</tt>.</p>
+
+<h5>Example:</h5>
+<pre>
+ <result> = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
+ <result> = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
+ <result> = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
+ <result> = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = and <ty> <var1>, <var2> <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_integer">integer</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>
+<div style="align: 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>
+</div>
+<h5>Example:</h5>
+<pre> <result> = and i32 4, %var <i>; yields {i32}:result = 4 & %var</i>
+ <result> = and i32 15, 40 <i>; yields {i32}:result = 8</i>
+ <result> = and i32 4, 8 <i>; yields {i32}: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> <result> = or <ty> <var1>, <var2> <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_integer">integer</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>
+<div style="align: 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>
+</div>
+<h5>Example:</h5>
+<pre> <result> = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
+ <result> = or i32 15, 40 <i>; yields {i32}:result = 47</i>
+ <result> = or i32 4, 8 <i>; yields {i32}: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> <result> = xor <ty> <var1>, <var2> <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_integer">integer</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>
+<div style="align: 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>
+</div>
+<p> </p>
+<h5>Example:</h5>
+<pre> <result> = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
+ <result> = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
+ <result> = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
+ <result> = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
+</pre>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="vectorops">Vector Operations</a>
+</div>
+
+<div class="doc_text">
+
+<p>LLVM supports several instructions to represent vector operations in a
+target-independent manner. This instructions cover the element-access and
+vector-specific operations needed to process vectors effectively. While LLVM
+does directly support these vector operations, many sophisticated algorithms
+will want to use target-specific intrinsics to take full advantage of a specific
+target.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+
+<pre>
+ <result> = extractelement <n x <ty>> <val>, i32 <idx> <i>; yields <ty></i>
+</pre>
+
+<h5>Overview:</h5>
+
+<p>
+The '<tt>extractelement</tt>' instruction extracts a single scalar
+element from a vector at a specified index.
+</p>
+
+
+<h5>Arguments:</h5>
+
+<p>
+The first operand of an '<tt>extractelement</tt>' instruction is a
+value of <a href="#t_vector">vector</a> type. The second operand is
+an index indicating the position from which to extract the element.
+The index may be a variable.</p>
+
+<h5>Semantics:</h5>
+
+<p>
+The result is a scalar of the same type as the element type of
+<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
+<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
+results are undefined.
+</p>
+
+<h5>Example:</h5>
+
+<pre>
+ %result = extractelement <4 x i32> %vec, i32 0 <i>; yields i32</i>
+</pre>
+</div>
+
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+
+<pre>
+ <result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> <i>; yields <n x <ty>></i>
+</pre>
+
+<h5>Overview:</h5>
+
+<p>
+The '<tt>insertelement</tt>' instruction inserts a scalar
+element into a vector at a specified index.
+</p>
+
+
+<h5>Arguments:</h5>
+
+<p>
+The first operand of an '<tt>insertelement</tt>' instruction is a
+value of <a href="#t_vector">vector</a> type. The second operand is a
+scalar value whose type must equal the element type of the first
+operand. The third operand is an index indicating the position at
+which to insert the value. The index may be a variable.</p>
+
+<h5>Semantics:</h5>
+
+<p>
+The result is a vector of the same type as <tt>val</tt>. Its
+element values are those of <tt>val</tt> except at position
+<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
+exceeds the length of <tt>val</tt>, the results are undefined.
+</p>
+
+<h5>Example:</h5>
+
+<pre>
+ %result = insertelement <4 x i32> %vec, i32 1, i32 0 <i>; yields <4 x i32></i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+
+<pre>
+ <result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <n x i32> <mask> <i>; yields <n x <ty>></i>
+</pre>
+
+<h5>Overview:</h5>
+
+<p>
+The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
+from two input vectors, returning a vector of the same type.
+</p>
+
+<h5>Arguments:</h5>
+
+<p>
+The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
+with types that match each other and types that match the result of the
+instruction. The third argument is a shuffle mask, which has the same number
+of elements as the other vector type, but whose element type is always 'i32'.
+</p>
+
+<p>
+The shuffle mask operand is required to be a constant vector with either
+constant integer or undef values.
+</p>
+
+<h5>Semantics:</h5>
+
+<p>
+The elements of the two input vectors are numbered from left to right across
+both of the vectors. The shuffle mask operand specifies, for each element of
+the result vector, which element of the two input registers the result element
+gets. The element selector may be undef (meaning "don't care") and the second
+operand may be undef if performing a shuffle from only one vector.
+</p>
+
+<h5>Example:</h5>
+
+<pre>
+ %result = shufflevector <4 x i32> %v1, <4 x i32> %v2,
+ <4 x i32> <i32 0, i32 4, i32 1, i32 5> <i>; yields <4 x i32></i>
+ %result = shufflevector <4 x i32> %v1, <4 x i32> undef,
+ <4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i> - Identity shuffle.
+</pre>
+</div>
+
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="memoryops">Memory Access and Addressing 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>
+ <result> = malloc <type>[, i32 <NumElements>][, align <alignment>] <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 '<tt>malloc</tt>' instruction allocates
+<tt>sizeof(<type>)*NumElements</tt>
+bytes of memory from the operating system and returns a pointer of the
+appropriate type to the program. If "NumElements" is specified, it is the
+number of elements allocated. If an alignment is specified, the value result
+of the allocation is guaranteed to be aligned to at least that boundary. If
+not specified, or if zero, the target can choose to align the allocation on any
+convenient boundary.</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 i8 ] <i>; yields {[%4 x i8]*}:array</i>
+
+ %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
+ %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
+ %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
+ %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
+ %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</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 <type> <value> <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>
+
+<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 no longer defined
+after this instruction executes.</p>
+
+<h5>Example:</h5>
+
+<pre>
+ %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
+ free [4 x i8]* %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>
+ <result> = alloca <type>[, i32 <NumElements>][, align <alignment>] <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 '<tt>alloca</tt>' instruction allocates <tt>sizeof(<type>)*NumElements</tt>
+bytes of memory on the runtime stack, returning a pointer of the
+appropriate type to the program. If "NumElements" is specified, it is the
+number of elements allocated. If an alignment is specified, the value result
+of the allocation is guaranteed to be aligned to at least that boundary. If
+not specified, or if zero, the target can choose to align the allocation on any
+convenient boundary.</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_unwind">unwind</a></tt>
+instructions), the memory is reclaimed.</p>
+
+<h5>Example:</h5>
+
+<pre>
+ %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
+ %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
+ %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
+ %ptr = alloca i32, align 1024 <i>; yields {i32*}: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> <result> = load <ty>* <pointer><br> <result> = volatile load <ty>* <pointer><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 from which to load. 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> i32 <i>; yields {i32*}:ptr</i>
+ <a
+ href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
+ %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i>
+ volatile store <ty> <value>, <ty>* <pointer> <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 in which to store it. The type of the '<tt><pointer></tt>'
+operand must be a pointer to the type of the '<tt><value></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><value></tt>'
+at the location specified by the '<tt><pointer></tt>' operand.</p>
+<h5>Example:</h5>
+<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
+ <a
+ href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
+ %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre>
+ <result> = getelementptr <ty>* <ptrval>{, <ty> <idx>}*
+</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 integer operands that indicate what
+elements of the aggregate object to index to. 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 or to a specific index in an array. When indexing into a
+structure, only <tt>i32</tt> integer constants are allowed. When indexing
+into an array or pointer, only integers of 32 or 64 bits are allowed, and will
+be sign extended to 64-bit values.</p>
+
+<p>For example, let's consider a C code fragment and how it gets
+compiled to LLVM:</p>
+
+<pre>
+ struct RT {
+ char A;
+ i32 B[10][20];
+ char C;
+ };
+ struct ST {
+ i32 X;
+ double Y;
+ struct RT Z;
+ };
+
+ define i32 *foo(struct ST *s) {
+ return &s[1].Z.B[5][13];
+ }
+</pre>
+
+<p>The LLVM code generated by the GCC frontend is:</p>
+
+<pre>
+ %RT = type { i8 , [10 x [20 x i32]], i8 }
+ %ST = type { i32, double, %RT }
+
+ implementation
+
+ define i32* %foo(%ST* %s) {
+ entry:
+ %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
+ ret i32* %reg
+ }
+</pre>
+
+<h5>Semantics:</h5>
+
+<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
+on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
+and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
+<a href="#t_integer">integer</a> type but the value will always be sign extended
+to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</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>{ i32, double, %RT
+}</tt>' type, a structure. The second index indexes into the third element of
+the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
+i8 }</tt>' type, another structure. The third index indexes into the second
+element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
+array. The two dimensions of the array are subscripted into, yielding an
+'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
+to this element, thus computing a value of '<tt>i32*</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>
+ define i32* %foo(%ST* %s) {
+ %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
+ %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
+ %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
+ %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
+ %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
+ ret i32* %t5
+ }
+</pre>
+
+<p>Note that it is undefined to access an array out of bounds: array and
+pointer indexes must always be within the defined bounds of the array type.
+The one exception for this rules is zero length arrays. These arrays are
+defined to be accessible as variable length arrays, which requires access
+beyond the zero'th element.</p>
+
+<p>The getelementptr instruction is often confusing. For some more insight
+into how it works, see <a href="GetElementPtr.html">the getelementptr
+FAQ</a>.</p>
+
+<h5>Example:</h5>
+
+<pre>
+ <i>; yields [12 x i8]*:aptr</i>
+ %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
+</pre>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
+</div>
+<div class="doc_text">
+<p>The instructions in this category are the conversion instructions (casting)
+which all take a single operand and a type. They perform various bit conversions
+on the operand.</p>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = trunc <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>
+The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
+</p>
+
+<h5>Arguments:</h5>
+<p>
+The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
+be an <a href="#t_integer">integer</a> type, and a type that specifies the size
+and type of the result, which must be an <a href="#t_integer">integer</a>
+type. The bit size of <tt>value</tt> must be larger than the bit size of
+<tt>ty2</tt>. Equal sized types are not allowed.</p>
+
+<h5>Semantics:</h5>
+<p>
+The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
+and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
+larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
+It will always truncate bits.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = trunc i32 257 to i8 <i>; yields i8:1</i>
+ %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
+ %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = zext <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>zext</tt>' instruction zero extends its operand to type
+<tt>ty2</tt>.</p>
+
+
+<h5>Arguments:</h5>
+<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
+<a href="#t_integer">integer</a> type, and a type to cast it to, which must
+also be of <a href="#t_integer">integer</a> type. The bit size of the
+<tt>value</tt> must be smaller than the bit size of the destination type,
+<tt>ty2</tt>.</p>
+
+<h5>Semantics:</h5>
+<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
+bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
+the operand and the type are the same size, no bit filling is done and the
+cast is considered a <i>no-op cast</i> because no bits change (only the type
+changes).</p>
+
+<p>When zero extending from i1, the result will always be either 0 or 1.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = zext i32 257 to i64 <i>; yields i64:257</i>
+ %Y = zext i1 true to i32 <i>; yields i32:1</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = sext <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
+
+<h5>Arguments:</h5>
+<p>
+The '<tt>sext</tt>' instruction takes a value to cast, which must be of
+<a href="#t_integer">integer</a> type, and a type to cast it to, which must
+also be of <a href="#t_integer">integer</a> type. The bit size of the
+<tt>value</tt> must be smaller than the bit size of the destination type,
+<tt>ty2</tt>.</p>
+
+<h5>Semantics:</h5>
+<p>
+The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
+bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
+the type <tt>ty2</tt>. When the the operand and the type are the same size,
+no bit filling is done and the cast is considered a <i>no-op cast</i> because
+no bits change (only the type changes).</p>
+
+<p>When sign extending from i1, the extension always results in -1 or 0.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
+ %Y = sext i1 true to i32 <i>; yields i32:-1</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+
+<pre>
+ <result> = fptrunc <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
+<tt>ty2</tt>.</p>
+
+
+<h5>Arguments:</h5>
+<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
+ point</a> value to cast and a <a href="#t_floating">floating point</a> type to
+cast it to. The size of <tt>value</tt> must be larger than the size of
+<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
+<i>no-op cast</i>.</p>
+
+<h5>Semantics:</h5>
+<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
+<a href="#t_floating">floating point</a> type to a smaller
+<a href="#t_floating">floating point</a> type. If the value cannot fit within
+the destination type, <tt>ty2</tt>, then the results are undefined.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
+ %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = fpext <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
+floating point value.</p>
+
+<h5>Arguments:</h5>
+<p>The '<tt>fpext</tt>' instruction takes a
+<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
+and a <a href="#t_floating">floating point</a> type to cast it to. The source
+type must be smaller than the destination type.</p>
+
+<h5>Semantics:</h5>
+<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
+<a href="t_floating">floating point</a> type to a larger
+<a href="t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
+used to make a <i>no-op cast</i> because it always changes bits. Use
+<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
+ %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = fp2uint <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
+unsigned integer equivalent of type <tt>ty2</tt>.
+</p>
+
+<h5>Arguments:</h5>
+<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
+<a href="#t_floating">floating point</a> value, and a type to cast it to, which
+must be an <a href="#t_integer">integer</a> type.</p>
+
+<h5>Semantics:</h5>
+<p> The '<tt>fp2uint</tt>' instruction converts its
+<a href="#t_floating">floating point</a> operand into the nearest (rounding
+towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
+the results are undefined.</p>
+
+<p>When converting to i1, the conversion is done as a comparison against
+zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
+If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
+ %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
+ %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = fptosi <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>fptosi</tt>' instruction converts
+<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
+</p>
+
<h5>Arguments:</h5>
-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>
+<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
+<a href="#t_floating">floating point</a> value, and a type to cast it to, which
+must also be an <a href="#t_integer">integer</a> type.</p>
<h5>Semantics:</h5>
+<p>The '<tt>fptosi</tt>' instruction converts its
+<a href="#t_floating">floating point</a> operand into the nearest (rounding
+towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
+the results are undefined.</p>
-The value produced is the integer or floating point sum of the two operands.<p>
+<p>When converting to i1, the conversion is done as a comparison against
+zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
+If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
<h5>Example:</h5>
<pre>
- <result> = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
+ %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
+ %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
+ %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = uitofp <ty> <value> to <ty2> <i>; yields ty2</i>
</pre>
+<h5>Overview:</h5>
+<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
+integer and converts that value to the <tt>ty2</tt> type.</p>
+
+
+<h5>Arguments:</h5>
+<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be an
+<a href="#t_integer">integer</a> value, and a type to cast it to, which must
+be a <a href="#t_floating">floating point</a> type.</p>
+
+<h5>Semantics:</h5>
+<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
+integer quantity and converts it to the corresponding floating point value. If
+the value cannot fit in the floating point value, the results are undefined.</p>
+
+
+<h5>Example:</h5>
+<pre>
+ %X = uitofp i32 257 to float <i>; yields float:257.0</i>
+ %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
+</pre>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_sub"><h4><hr size=0>'<tt>sub</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = sub <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+ <result> = sitofp <ty> <value> to <ty2> <i>; yields ty2</i>
</pre>
<h5>Overview:</h5>
+<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
+integer and converts that value to the <tt>ty2</tt> type.</p>
+
+<h5>Arguments:</h5>
+<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be an
+<a href="#t_integer">integer</a> value, and a type to cast it to, which must be
+a <a href="#t_floating">floating point</a> type.</p>
+
+<h5>Semantics:</h5>
+<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
+integer quantity and converts it to the corresponding floating point value. If
+the value cannot fit in the floating point value, the results are undefined.</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = sitofp i32 257 to float <i>; yields float:257.0</i>
+ %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
-The '<tt>sub</tt>' instruction returns the difference of its two operands.<p>
+<h5>Syntax:</h5>
+<pre>
+ <result> = ptrtoint <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
-Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
-instruction present in most other intermediate representations.<p>
+<h5>Overview:</h5>
+<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
+the integer type <tt>ty2</tt>.</p>
<h5>Arguments:</h5>
+<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
+must be a <a href="t_pointer">pointer</a> value, and a type to cast it to
+<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
+
+<h5>Semantics:</h5>
+<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
+<tt>ty2</tt> by interpreting the pointer value as an integer and either
+truncating or zero extending that value to the size of the integer type. If
+<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
+<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
+are the same size, then nothing is done (<i>no-op cast</i>).</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
+ %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = inttoptr <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
-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>Overview:</h5>
+<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
+a pointer type, <tt>ty2</tt>.</p>
+
+<h5>Arguments:</h5>
+<p>The '<tt>inttoptr</tt>' instruction takes an <a href="i_integer">integer</a>
+value to cast, and a type to cast it to, which must be a
+<a href="#t_pointer">pointer</a> type.
<h5>Semantics:</h5>
+<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
+<tt>ty2</tt> by applying either a zero extension or a truncation depending on
+the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
+size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
+the size of a pointer then a zero extension is done. If they are the same size,
+nothing is done (<i>no-op cast</i>).</p>
+
+<h5>Example:</h5>
+<pre>
+ %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
+ %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
+ %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <result> = bitcast <ty> <value> to <ty2> <i>; yields ty2</i>
+</pre>
+
+<h5>Overview:</h5>
+<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
+<tt>ty2</tt> without changing any bits.</p>
+
+<h5>Arguments:</h5>
+<p>The '<tt>bitcast</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. The bit sizes of <tt>value</tt>
+and the destination type, <tt>ty2</tt>, must be identical. If the source
+type is a pointer, the destination type must also be a pointer.</p>
-The value produced is the integer or floating point difference of the two
-operands.<p>
+<h5>Semantics:</h5>
+<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
+<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
+this conversion. The conversion is done as if the <tt>value</tt> had been
+stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
+converted to other pointer types with this instruction. To convert pointers to
+other types, use the <a href="#i_inttoptr">inttoptr</a> or
+<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
<h5>Example:</h5>
<pre>
- <result> = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
- <result> = sub int 0, %val <i>; yields {int}:result = -%var</i>
+ %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
+ %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
+ %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
+</pre>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
+<div class="doc_text">
+<p>The instructions in this category are the "miscellaneous"
+instructions, which defy better classification.</p>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = icmp <cond> <ty> <var1>, <var2>
+<i>; yields {i1}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
+of its two integer operands.</p>
+<h5>Arguments:</h5>
+<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
+the condition code which indicates the kind of comparison to perform. It is not
+a value, just a keyword. The possibilities for the condition code are:
+<ol>
+ <li><tt>eq</tt>: equal</li>
+ <li><tt>ne</tt>: not equal </li>
+ <li><tt>ugt</tt>: unsigned greater than</li>
+ <li><tt>uge</tt>: unsigned greater or equal</li>
+ <li><tt>ult</tt>: unsigned less than</li>
+ <li><tt>ule</tt>: unsigned less or equal</li>
+ <li><tt>sgt</tt>: signed greater than</li>
+ <li><tt>sge</tt>: signed greater or equal</li>
+ <li><tt>slt</tt>: signed less than</li>
+ <li><tt>sle</tt>: signed less or equal</li>
+</ol>
+<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
+<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
+<h5>Semantics:</h5>
+<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
+the condition code given as <tt>cond</tt>. The comparison performed always
+yields a <a href="#t_primitive">i1</a> result, as follows:
+<ol>
+ <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
+ <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
+ </li>
+ <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
+ <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
+ <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
+ <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
+ <li><tt>uge</tt>: interprets the operands as unsigned values and yields
+ <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
+ <li><tt>ult</tt>: interprets the operands as unsigned values and yields
+ <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
+ <li><tt>ule</tt>: interprets the operands as unsigned values and yields
+ <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
+ <li><tt>sgt</tt>: interprets the operands as signed values and yields
+ <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
+ <li><tt>sge</tt>: interprets the operands as signed values and yields
+ <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
+ <li><tt>slt</tt>: interprets the operands as signed values and yields
+ <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
+ <li><tt>sle</tt>: interprets the operands as signed values and yields
+ <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
+</ol>
+<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
+values are treated as integers and then compared.</p>
+
+<h5>Example:</h5>
+<pre> <result> = icmp eq i32 4, 5 <i>; yields: result=false</i>
+ <result> = icmp ne float* %X, %X <i>; yields: result=false</i>
+ <result> = icmp ult i16 4, 5 <i>; yields: result=true</i>
+ <result> = icmp sgt i16 4, 5 <i>; yields: result=false</i>
+ <result> = icmp ule i16 -4, 5 <i>; yields: result=false</i>
+ <result> = icmp sge i16 4, 5 <i>; yields: result=false</i>
+</pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
+</div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = fcmp <cond> <ty> <var1>, <var2>
+<i>; yields {i1}:result</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
+of its floating point operands.</p>
+<h5>Arguments:</h5>
+<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
+the condition code which indicates the kind of comparison to perform. It is not
+a value, just a keyword. The possibilities for the condition code are:
+<ol>
+ <li><tt>false</tt>: no comparison, always returns false</li>
+ <li><tt>oeq</tt>: ordered and equal</li>
+ <li><tt>ogt</tt>: ordered and greater than </li>
+ <li><tt>oge</tt>: ordered and greater than or equal</li>
+ <li><tt>olt</tt>: ordered and less than </li>
+ <li><tt>ole</tt>: ordered and less than or equal</li>
+ <li><tt>one</tt>: ordered and not equal</li>
+ <li><tt>ord</tt>: ordered (no nans)</li>
+ <li><tt>ueq</tt>: unordered or equal</li>
+ <li><tt>ugt</tt>: unordered or greater than </li>
+ <li><tt>uge</tt>: unordered or greater than or equal</li>
+ <li><tt>ult</tt>: unordered or less than </li>
+ <li><tt>ule</tt>: unordered or less than or equal</li>
+ <li><tt>une</tt>: unordered or not equal</li>
+ <li><tt>uno</tt>: unordered (either nans)</li>
+ <li><tt>true</tt>: no comparison, always returns true</li>
+</ol>
+<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
+<i>unordered</i> means that either operand may be a QNAN.</p>
+<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
+<a href="#t_floating">floating point</a> typed. They must have identical
+types.</p>
+<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
+<i>unordered</i> means that either operand is a QNAN.</p>
+<h5>Semantics:</h5>
+<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
+the condition code given as <tt>cond</tt>. The comparison performed always
+yields a <a href="#t_primitive">i1</a> result, as follows:
+<ol>
+ <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
+ <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
+ <tt>var1</tt> is equal to <tt>var2</tt>.</li>
+ <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
+ <tt>var1</tt> is greather than <tt>var2</tt>.</li>
+ <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
+ <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
+ <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
+ <tt>var1</tt> is less than <tt>var2</tt>.</li>
+ <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
+ <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
+ <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
+ <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
+ <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
+ <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
+ <tt>var1</tt> is equal to <tt>var2</tt>.</li>
+ <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
+ <tt>var1</tt> is greater than <tt>var2</tt>.</li>
+ <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
+ <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
+ <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
+ <tt>var1</tt> is less than <tt>var2</tt>.</li>
+ <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
+ <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
+ <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
+ <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
+ <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
+ <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
+</ol>
+
+<h5>Example:</h5>
+<pre> <result> = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
+ <result> = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
+ <result> = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
+ <result> = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
</pre>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_mul"><h4><hr size=0>'<tt>mul</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = phi <ty> [ <val0>, <label0>], ...<br></pre>
+<h5>Overview:</h5>
+<p>The '<tt>phi</tt>' instruction is used to implement the φ 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 i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add i32 %indvar, 1<br> br label %Loop<br></pre>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_select">'<tt>select</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
+
<pre>
- <result> = mul <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+ <result> = select i1 <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
</pre>
<h5>Overview:</h5>
-The '<tt>mul</tt>' instruction returns the product of its two operands.<p>
+
+<p>
+The '<tt>select</tt>' instruction is used to choose one value based on a
+condition, without branching.
+</p>
+
<h5>Arguments:</h5>
-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>
+
+<p>
+The '<tt>select</tt>' instruction requires a boolean value indicating the condition, and two values of the same <a href="#t_firstclass">first class</a> type.
+</p>
<h5>Semantics:</h5>
-The value produced is the integer or floating point product of the two
-operands.<p>
+<p>
+If the boolean condition evaluates to true, the instruction returns the first
+value argument; otherwise, it returns the second value argument.
+</p>
+
+<h5>Example:</h5>
+
+<pre>
+ %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</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>
+ <result> = [tail] call [<a href="#callingconv">cconv</a>] <ty>* <fnptrval>(<param list>)
+</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>The optional "tail" marker indicates whether the callee function accesses
+ any allocas or varargs in the caller. If the "tail" marker is present, the
+ function call is eligible for tail call optimization. Note that calls may
+ be marked "tail" even if they do not occur before a <a
+ href="#i_ret"><tt>ret</tt></a> instruction.
+ </li>
+ <li>
+ <p>The optional "cconv" marker indicates which <a href="callingconv">calling
+ convention</a> the call should use. If none is specified, the call defaults
+ to using C calling conventions.
+ </li>
+ <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. This type can be omitted if the function is not varargs and
+ if the function type does not return a pointer to a function.</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 value.</p>
+ </li>
+ <li>
+ <p>'<tt>function args</tt>': argument list whose types match the
+ function signature argument types. All arguments must be of
+ <a href="#t_firstclass">first class</a> type. If the function signature
+ indicates the function accepts a variable number of arguments, the extra
+ arguments can be specified.</p>
+ </li>
+</ol>
-There is no signed vs unsigned multiplication. The appropriate action is taken
-based on the type of the operand. <p>
+<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>
- <result> = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
+ %retval = call i32 %test(i32 %argc)
+ call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
+ %X = tail call i32 %foo()
+ %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
</pre>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_div"><h4><hr size=0>'<tt>div</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
+
<pre>
- <result> = div <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+ <resultval> = va_arg <va_list*> <arglist>, <argty>
</pre>
<h5>Overview:</h5>
-The '<tt>div</tt>' instruction returns the quotient of its two operands.<p>
+<p>The '<tt>va_arg</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>va_list*</tt> value and the type of
+the argument. It returns a value of the specified argument type and
+increments the <tt>va_list</tt> to point to the next argument. Again, the
+actual type of <tt>va_list</tt> is target specific.</p>
+
+<h5>Semantics:</h5>
+
+<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
+type from the specified <tt>va_list</tt> and causes the
+<tt>va_list</tt> to point to the next argument. 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>va_arg</tt> is an LLVM instruction instead of an <a
+href="#intrinsics">intrinsic function</a> because it takes a 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>To learn how to add an intrinsic function, please see the <a
+href="ExtendingLLVM.html">Extending LLVM Guide</a>.
+</p>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="int_varargs">Variable Argument Handling Intrinsics</a>
+</div>
-<h5>Arguments:</h5>
+<div class="doc_text">
-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>
+<p>Variable argument support is defined in LLVM with the <a
+ href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
+intrinsic functions. These functions are related to the similarly
+named macros defined in the <tt><stdarg.h></tt> header file.</p>
-<h5>Semantics:</h5>
+<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>
-The value produced is the integer or floating point quotient of the two
-operands.<p>
+<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
+instruction and the variable argument handling intrinsic functions are
+used.</p>
-<h5>Example:</h5>
<pre>
- <result> = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
-</pre>
+define i32 @test(i32 %X, ...) {
+ ; Initialize variable argument processing
+ %ap = alloca i8 *
+ %ap2 = bitcast i8** %ap to i8*
+ call void @llvm.va_start(i8* %ap2)
+
+ ; Read a single integer argument
+ %tmp = va_arg i8 ** %ap, i32
+
+ ; Demonstrate usage of llvm.va_copy and llvm.va_end
+ %aq = alloca i8 *
+ %aq2 = bitcast i8** %aq to i8*
+ call void @llvm.va_copy(i8 *%aq2, i8* %ap2)
+ call void @llvm.va_end(i8* %aq2)
+
+ ; Stop processing of arguments.
+ call void @llvm.va_end(i8* %ap2)
+ ret i32 %tmp
+}
+declare void @llvm.va_start(i8*)
+declare void @llvm.va_copy(i8*, i8*)
+declare void @llvm.va_end(i8*)
+</pre>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_rem"><h4><hr size=0>'<tt>rem</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
+</div>
-<h5>Syntax:</h5>
-<pre>
- <result> = rem <ty> <var1>, <var2> <i>; yields {ty}:result</i>
-</pre>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> declare void %llvm.va_start(i8* <arglist>)<br></pre>
<h5>Overview:</h5>
-The '<tt>rem</tt>' instruction returns the remainder from the division of its two operands.<p>
+<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
+<tt>*<arglist></tt> for subsequent use by <tt><a
+href="#i_va_arg">va_arg</a></tt>.</p>
<h5>Arguments:</h5>
-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>The argument is a pointer to a <tt>va_list</tt> element to initialize.</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>Semantics:</h5>
-<h5>Example:</h5>
-<pre>
- <result> = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
-</pre>
+<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 the
+<tt>va_list</tt> element the argument points to, so that the next call to
+<tt>va_arg</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>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_setcc"><h4><hr size=0>'<tt>set<i>cc</i></tt>' Instructions</h4><ul>
+<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>
- <result> = seteq <ty> <var1>, <var2> <i>; yields {bool}:result</i>
- <result> = setne <ty> <var1>, <var2> <i>; yields {bool}:result</i>
- <result> = setlt <ty> <var1>, <var2> <i>; yields {bool}:result</i>
- <result> = setgt <ty> <var1>, <var2> <i>; yields {bool}:result</i>
- <result> = setle <ty> <var1>, <var2> <i>; yields {bool}:result</i>
- <result> = setge <ty> <var1>, <var2> <i>; yields {bool}:result</i>
-</pre>
+<pre> declare void @llvm.va_end(i8* <arglist>)<br></pre>
+<h5>Overview:</h5>
-<h5>Overview:</h5> The '<tt>set<i>cc</i></tt>' family of instructions returns a
-boolean value based on a comparison of their two operands.<p>
+<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt><arglist></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> The two arguments to the '<tt>set<i>cc</i></tt>'
-instructions must be of <a href="#t_firstclass">first class</a> or <a
-href="#t_pointer">pointer</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>Arguments:</h5>
-The '<tt>setlt</tt>', '<tt>setgt</tt>', '<tt>setle</tt>', and '<tt>setge</tt>'
-instructions do not operate on '<tt>bool</tt>' typed arguments.<p>
+<p>The argument is a <tt>va_list</tt> to destroy.</p>
<h5>Semantics:</h5>
-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>
+<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>
-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>
+</div>
-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>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
+</div>
-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>
+<div class="doc_text">
-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>Syntax:</h5>
-<h5>Example:</h5>
<pre>
- <result> = seteq int 4, 5 <i>; yields {bool}:result = false</i>
- <result> = setne float 4, 5 <i>; yields {bool}:result = true</i>
- <result> = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
- <result> = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
- <result> = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
- <result> = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
+ declare void @llvm.va_copy(i8* <destarglist>, i8* <srcarglist>)
</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 first argument is a pointer to a <tt>va_list</tt> element to initialize.
+The second argument is a pointer to a <tt>va_list</tt> element to copy from.</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 destination list. This intrinsic is necessary
+because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
+arbitrarily complex and require memory allocation, for example.</p>
+</div>
<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="bitwiseops">Bitwise Binary Operations
-</b></font></td></tr></table><ul>
+<div class="doc_subsection">
+ <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
+</div>
-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 class="doc_text">
+
+<p>
+LLVM support for <a href="GarbageCollection.html">Accurate Garbage
+Collection</a> requires the implementation and generation of these intrinsics.
+These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
+stack</a>, as well as garbage collector implementations that require <a
+href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
+Front-ends for type-safe garbage collected languages should generate these
+intrinsics to make use of the LLVM garbage collectors. For more details, see <a
+href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_and"><h4><hr size=0>'<tt>and</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
+
<pre>
- <result> = and <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+ declare void @llvm.gcroot(<ty>** %ptrloc, <ty2>* %metadata)
</pre>
<h5>Overview:</h5>
-The '<tt>and</tt>' instruction returns the bitwise logical and of its two operands.<p>
-<h5>Arguments:</h5>
+<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
+the code generator, and allows some metadata to be associated with it.</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>Arguments:</h5>
+<p>The first argument specifies the address of a stack object that contains the
+root pointer. The second pointer (which must be either a constant or a global
+value address) contains the meta-data to be associated with the root.</p>
<h5>Semantics:</h5>
-The truth table used for the '<tt>and</tt>' instruction is:<p>
-
-<center><table border=1 cellspacing=0 cellpadding=4>
-<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>
-</table></center><p>
-
-
-<h5>Example:</h5>
-<pre>
- <result> = and int 4, %var <i>; yields {int}:result = 4 & %var</i>
- <result> = and int 15, 40 <i>; yields {int}:result = 8</i>
- <result> = and int 4, 8 <i>; yields {int}:result = 0</i>
-</pre>
+<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
+location. At compile-time, the code generator generates information to allow
+the runtime to find the pointer at GC safe points.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_or"><h4><hr size=0>'<tt>or</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
+
<pre>
- <result> = or <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+ declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
</pre>
-<h5>Overview:</h5> The '<tt>or</tt>' instruction returns the bitwise logical
-inclusive or of its two operands.<p>
+<h5>Overview:</h5>
-<h5>Arguments:</h5>
+<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
+locations, allowing garbage collector implementations that require read
+barriers.</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>Arguments:</h5>
+<p>The second argument is the address to read from, which should be an address
+allocated from the garbage collector. The first object is a pointer to the
+start of the referenced object, if needed by the language runtime (otherwise
+null).</p>
<h5>Semantics:</h5>
-The truth table used for the '<tt>or</tt>' instruction is:<p>
-
-<center><table border=1 cellspacing=0 cellpadding=4>
-<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>
-</table></center><p>
+<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
+instruction, but may be replaced with substantially more complex code by the
+garbage collector runtime, as needed.</p>
-
-<h5>Example:</h5>
-<pre>
- <result> = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
- <result> = or int 15, 40 <i>; yields {int}:result = 47</i>
- <result> = or int 4, 8 <i>; yields {int}:result = 12</i>
-</pre>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_xor"><h4><hr size=0>'<tt>xor</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
+
<pre>
- <result> = xor <ty> <var1>, <var2> <i>; yields {ty}:result</i>
+ declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
</pre>
<h5>Overview:</h5>
-The '<tt>xor</tt>' instruction returns the bitwise logical exclusive or of its
-two operands.<p>
+<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
+locations, allowing garbage collector implementations that require write
+barriers (such as generational or reference counting collectors).</p>
<h5>Arguments:</h5>
-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>
-
+<p>The first argument is the reference to store, the second is the start of the
+object to store it to, and the third is the address of the field of Obj to
+store to. If the runtime does not require a pointer to the object, Obj may be
+null.</p>
<h5>Semantics:</h5>
-The truth table used for the '<tt>xor</tt>' instruction is:<p>
+<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
+instruction, but may be replaced with substantially more complex code by the
+garbage collector runtime, as needed.</p>
-<center><table border=1 cellspacing=0 cellpadding=4>
-<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>
-</table></center><p>
+</div>
-<h5>Example:</h5>
-<pre>
- <result> = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
- <result> = xor int 15, 40 <i>; yields {int}:result = 39</i>
- <result> = xor int 4, 8 <i>; yields {int}:result = 12</i>
-</pre>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="int_codegen">Code Generator Intrinsics</a>
+</div>
+
+<div class="doc_text">
+<p>
+These intrinsics are provided by LLVM to expose special features that may only
+be implemented with code generator support.
+</p>
+
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_shl"><h4><hr size=0>'<tt>shl</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = shl <ty> <var1>, ubyte <var2> <i>; yields {ty}:result</i>
+ declare i8 *@llvm.returnaddress(i32 <level>)
</pre>
<h5>Overview:</h5>
-The '<tt>shl</tt>' instruction returns the first operand shifted to the left a
-specified number of bits.
+<p>
+The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
+target-specific value indicating the return address of the current function
+or one of its callers.
+</p>
<h5>Arguments:</h5>
-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>
+<p>
+The argument to this intrinsic indicates which function to return the address
+for. Zero indicates the calling function, one indicates its caller, etc. The
+argument is <b>required</b> to be a constant integer value.
+</p>
<h5>Semantics:</h5>
-The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.<p>
-
+<p>
+The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
+the return address of the specified call frame, or zero if it cannot be
+identified. The value returned by this intrinsic is likely to be incorrect or 0
+for arguments other than zero, so it should only be used for debugging purposes.
+</p>
-<h5>Example:</h5>
-<pre>
- <result> = shl int 4, ubyte %var <i>; yields {int}:result = 4 << %var</i>
- <result> = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
- <result> = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
-</pre>
+<p>
+Note that calling this intrinsic does not prevent function inlining or other
+aggressive transformations, so the value returned may not be that of the obvious
+source-language caller.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_shr"><h4><hr size=0>'<tt>shr</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
+</div>
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = shr <ty> <var1>, ubyte <var2> <i>; yields {ty}:result</i>
+ declare i8 *@llvm.frameaddress(i32 <level>)
</pre>
<h5>Overview:</h5>
-The '<tt>shr</tt>' instruction returns the first operand shifted to the right a specified number of bits.
+
+<p>
+The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
+target-specific frame pointer value for the specified stack frame.
+</p>
<h5>Arguments:</h5>
-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>
+
+<p>
+The argument to this intrinsic indicates which function to return the frame
+pointer for. Zero indicates the calling function, one indicates its caller,
+etc. The argument is <b>required</b> to be a constant integer value.
+</p>
<h5>Semantics:</h5>
-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>
+<p>
+The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
+the frame address of the specified call frame, or zero if it cannot be
+identified. The value returned by this intrinsic is likely to be incorrect or 0
+for arguments other than zero, so it should only be used for debugging purposes.
+</p>
-<h5>Example:</h5>
-<pre>
- <result> = shr int 4, ubyte %var <i>; yields {int}:result = 4 >> %var</i>
- <result> = shr int 4, ubyte 1 <i>; yields {int}:result = 2</i>
- <result> = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
- <result> = shr int 4, ubyte 3 <i>; yields {int}:result = 0</i>
-</pre>
+<p>
+Note that calling this intrinsic does not prevent function inlining or other
+aggressive transformations, so the value returned may not be that of the obvious
+source-language caller.
+</p>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
+</div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre>
+ declare i8 *@llvm.stacksave()
+</pre>
+<h5>Overview:</h5>
-<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="memoryops">Memory Access Operations
-</b></font></td></tr></table><ul>
+<p>
+The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
+the function stack, for use with <a href="#i_stackrestore">
+<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
+features like scoped automatic variable sized arrays in C99.
+</p>
+
+<h5>Semantics:</h5>
-Accessing memory in SSA form is, well, sticky at best. This section describes how to read, write, allocate and free memory in LLVM.<p>
+<p>
+This intrinsic returns a opaque pointer value that can be passed to <a
+href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
+<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
+<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
+state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
+practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
+that were allocated after the <tt>llvm.stacksave</tt> was executed.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_malloc"><h4><hr size=0>'<tt>malloc</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = malloc <type>, uint <NumElements> <i>; yields {type*}:result</i>
- <result> = malloc <type> <i>; yields {type*}:result</i>
+ declare void @llvm.stackrestore(i8 * %ptr)
</pre>
<h5>Overview:</h5>
-The '<tt>malloc</tt>' instruction allocates memory from the system heap and returns a pointer to it.<p>
-
-<h5>Arguments:</h5>
-
-The the '<tt>malloc</tt>' instruction allocates
-<tt>sizeof(<type>)*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>
-'<tt>type</tt>' must be a sized type<p>
+<p>
+The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
+the function stack to the state it was in when the corresponding <a
+href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
+useful for implementing language features like scoped automatic variable sized
+arrays in C99.
+</p>
<h5>Semantics:</h5>
-Memory is allocated, a pointer is returned.<p>
-<h5>Example:</h5>
-<pre>
- %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
+<p>
+See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
+</p>
- %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>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_free"><h4><hr size=0>'<tt>free</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- free <type> <value> <i>; yields {void}</i>
+ declare void @llvm.prefetch(i8 * <address>,
+ i32 <rw>, i32 <locality>)
</pre>
-
<h5>Overview:</h5>
-The '<tt>free</tt>' instruction returns memory back to the unused memory heap, to be reallocated in the future.<p>
-<h5>Arguments:</h5>
+<p>
+The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
+a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
+no
+effect on the behavior of the program but can change its performance
+characteristics.
+</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>Arguments:</h5>
+<p>
+<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
+determining if the fetch should be for a read (0) or write (1), and
+<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
+locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
+<tt>locality</tt> arguments must be constant integers.
+</p>
<h5>Semantics:</h5>
-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>
+<p>
+This intrinsic does not modify the behavior of the program. In particular,
+prefetches cannot trap and do not produce a value. On targets that support this
+intrinsic, the prefetch can provide hints to the processor cache for better
+performance.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_alloca"><h4><hr size=0>'<tt>alloca</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = alloca <type>, uint <NumElements> <i>; yields {type*}:result</i>
- <result> = alloca <type> <i>; yields {type*}:result</i>
+ declare void @llvm.pcmarker( i32 <id> )
</pre>
<h5>Overview:</h5>
-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 '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
+(PC) in a region of
+code to simulators and other tools. The method is target specific, but it is
+expected that the marker will use exported symbols to transmit the PC of the marker.
+The marker makes no guarantees that it will remain with any specific instruction
+after optimizations. It is possible that the presence of a marker will inhibit
+optimizations. The intended use is to be inserted after optimizations to allow
+correlations of simulation runs.
+</p>
-The the '<tt>alloca</tt>' instruction allocates
-<tt>sizeof(<type>)*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>
+<h5>Arguments:</h5>
-'<tt>type</tt>' may be any sized type.<p>
+<p>
+<tt>id</tt> is a numerical id identifying the marker.
+</p>
<h5>Semantics:</h5>
-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, as well as spilled variables.<p>
-
-<h5>Example:</h5>
-<pre>
- %ptr = alloca int <i>; yields {int*}:ptr</i>
- %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
-</pre>
+<p>
+This intrinsic does not modify the behavior of the program. Backends that do not
+support this intrinisic may ignore it.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_load"><h4><hr size=0>'<tt>load</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = load <ty>* <pointer>
+ declare i64 @llvm.readcyclecounter( )
</pre>
<h5>Overview:</h5>
-The '<tt>load</tt>' instruction is used to read from memory.<p>
-<h5>Arguments:</h5>
-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.<p>
+<p>
+The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
+counter register (or similar low latency, high accuracy clocks) on those targets
+that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
+As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
+should only be used for small timings.
+</p>
<h5>Semantics:</h5>
-The location of memory pointed to is loaded.
+<p>
+When directly supported, reading the cycle counter should not modify any memory.
+Implementations are allowed to either return a application specific value or a
+system wide value. On backends without support, this is lowered to a constant 0.
+</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_subsection">
+ <a name="int_libc">Standard C Library Intrinsics</a>
+</div>
+<div class="doc_text">
+<p>
+LLVM provides intrinsics for a few important standard C library functions.
+These intrinsics allow source-language front-ends to pass information about the
+alignment of the pointer arguments to the code generator, providing opportunity
+for more efficient code generation.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_store"><h4><hr size=0>'<tt>store</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i>
+ declare void @llvm.memcpy.i32(i8 * <dest>, i8 * <src>,
+ i32 <len>, i32 <align>)
+ declare void @llvm.memcpy.i64(i8 * <dest>, i8 * <src>,
+ i64 <len>, i32 <align>)
</pre>
<h5>Overview:</h5>
-The '<tt>store</tt>' instruction is used to write to memory.<p>
-<h5>Arguments:</h5>
+<p>
+The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
+location to the destination location.
+</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><pointer></tt>'
-operand must be a pointer to the type of the '<tt><value></tt>'
-operand.<p>
+<p>
+Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
+intrinsics do not return a value, and takes an extra alignment argument.
+</p>
-<h5>Semantics:</h5> The contents of memory are updated to contain
-'<tt><value></tt>' at the location specified by the
-'<tt><pointer></tt>' operand.<p>
+<h5>Arguments:</h5>
-<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>
+<p>
+The first argument is a pointer to the destination, the second is a pointer to
+the source. The third argument is an 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 both the source and destination pointers are aligned
+to that boundary.
+</p>
+<h5>Semantics:</h5>
+<p>
+The '<tt>llvm.memcpy.*</tt>' intrinsics copy 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>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_getelementptr"><h4><hr size=0>'<tt>getelementptr</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = getelementptr <ty>* <ptrval>{, uint <aidx>|, ubyte <sidx>}*
+ declare void @llvm.memmove.i32(i8 * <dest>, i8 * <src>,
+ i32 <len>, i32 <align>)
+ declare void @llvm.memmove.i64(i8 * <dest>, i8 * <src>,
+ i64 <len>, i32 <align>)
</pre>
<h5>Overview:</h5>
-The '<tt>getelementptr</tt>' instruction is used to get the address of a
-subelement of an aggregate data structure.<p>
-
-<h5>Arguments:</h5>
-
-This instruction takes a list of <tt>uint</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>
-
-For example, lets consider a C code fragment and how it gets compiled to
-LLVM:<p>
-
-<pre>
-struct RT {
- char A;
- int B[10][20];
- char C;
-};
-struct ST {
- int X;
- double Y;
- struct RT Z;
-};
+<p>
+The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
+location to the destination location. It is similar to the
+'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
+</p>
-int *foo(struct ST *s) {
- return &s[1].Z.B[5][13];
-}
-</pre>
+<p>
+Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
+intrinsics do not return a value, and takes an extra alignment argument.
+</p>
-The LLVM code generated by the GCC frontend is:
+<h5>Arguments:</h5>
-<pre>
-%RT = type { sbyte, [10 x [20 x int]], sbyte }
-%ST = type { int, double, %RT }
+<p>
+The first argument is a pointer to the destination, the second is a pointer to
+the source. The third argument is an integer argument
+specifying the number of bytes to copy, and the fourth argument is the alignment
+of the source and destination locations.
+</p>
-int* "foo"(%ST* %s) {
- %reg = getelementptr %ST* %s, uint 1, ubyte 2, ubyte 1, uint 5, uint 13
- ret int* %reg
-}
-</pre>
+<p>
+If the call to this intrinisic has an alignment value that is not 0 or 1, then
+the caller guarantees that the source and destination pointers are aligned to
+that boundary.
+</p>
<h5>Semantics:</h5>
-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>uint</tt>' values, and <a
-href="t_struct">structure</a> types require '<tt>ubyte</tt>'
-<b>constants</b>.<p>
+<p>
+The '<tt>llvm.memmove.*</tt>' intrinsics copy 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>
+
-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>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
+</div>
-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>
+<div class="doc_text">
+<h5>Syntax:</h5>
<pre>
-int* "foo"(%ST* %s) {
- %t1 = getelementptr %ST* %s , uint 1 <i>; yields %ST*:%t1</i>
- %t2 = getelementptr %ST* %t1, uint 0, ubyte 2 <i>; yields %RT*:%t2</i>
- %t3 = getelementptr %RT* %t2, uint 0, ubyte 1 <i>; yields [10 x [20 x int]]*:%t3</i>
- %t4 = getelementptr [10 x [20 x int]]* %t3, uint 0, uint 5 <i>; yields [20 x int]*:%t4</i>
- %t5 = getelementptr [20 x int]* %t4, uint 0, uint 13 <i>; yields int*:%t5</i>
- ret int* %t5
-}
+ declare void @llvm.memset.i32(i8 * <dest>, i8 <val>,
+ i32 <len>, i32 <align>)
+ declare void @llvm.memset.i64(i8 * <dest>, i8 <val>,
+ i64 <len>, i32 <align>)
</pre>
+<h5>Overview:</h5>
+<p>
+The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
+byte value.
+</p>
-<h5>Example:</h5>
-<pre>
- <i>; yields [12 x ubyte]*:aptr</i>
- %aptr = getelementptr {int, [12 x ubyte]}* %sptr, uint 0, ubyte 1
-</pre>
+<p>
+Note that, unlike the standard libc function, the <tt>llvm.memset</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 to fill, the second is the
+byte value to fill it with, the third argument is an integer
+argument specifying the number of bytes to fill, and the fourth argument is the
+known alignment of destination location.
+</p>
-<!-- ======================================================================= -->
-</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
-<tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b>
-<a name="otherops">Other Operations
-</b></font></td></tr></table><ul>
+<p>
+If the call to this intrinisic has an alignment value that is not 0 or 1, then
+the caller guarantees that the destination pointer is aligned to that boundary.
+</p>
+
+<h5>Semantics:</h5>
-The instructions in this catagory are the "miscellaneous" functions, that defy better classification.<p>
+<p>
+The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
+the
+destination location. 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>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_phi"><h4><hr size=0>'<tt>phi</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = phi <ty> [ <val0>, <label0>], ...
+ declare float @llvm.sqrt.f32(float %Val)
+ declare double @llvm.sqrt.f64(double %Val)
</pre>
<h5>Overview:</h5>
-The '<tt>phi</tt>' instruction is used to implement the φ node in the SSA
-graph representing the function.<p>
+<p>
+The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
+returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
+<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
+negative numbers (which allows for better optimization).
+</p>
<h5>Arguments:</h5>
-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.<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>
+<p>
+The argument and return value are floating point numbers of the same type.
+</p>
<h5>Semantics:</h5>
-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...
- %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
- %nextindvar = add uint %indvar, 1
- br label %Loop
-</pre>
-
+<p>
+This function returns the sqrt of the specified operand if it is a positive
+floating point number.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_cast"><h4><hr size=0>'<tt>cast .. to</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = cast <ty> <value> to <ty2> <i>; yields ty2</i>
+ declare float @llvm.powi.f32(float %Val, i32 %power)
+ declare double @llvm.powi.f64(double %Val, i32 %power)
</pre>
<h5>Overview:</h5>
-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>
+<p>
+The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
+specified (positive or negative) power. The order of evaluation of
+multiplications is not defined.
+</p>
<h5>Arguments:</h5>
-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 first class type.<p>
+<p>
+The second argument is an integer power, and the first is a value to raise to
+that power.
+</p>
<h5>Semantics:</h5>
-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>
+This function returns the first value raised to the second power with an
+unspecified sequence of rounding operations.</p>
+</div>
+
-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>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="int_manip">Bit Manipulation Intrinsics</a>
+</div>
+
+<div class="doc_text">
+<p>
+LLVM provides intrinsics for a few important bit manipulation operations.
+These allow efficient code generation for some algorithms.
+</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>
+</div>
-<h5>Example:</h5>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
<pre>
- %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
- %Y = cast int 123 to bool <i>; yields bool:true</i>
+ declare i16 @llvm.bswap.i16(i16 <id>)
+ declare i32 @llvm.bswap.i32(i32 <id>)
+ declare i64 @llvm.bswap.i64(i64 <id>)
</pre>
+<h5>Overview:</h5>
+
+<p>
+The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
+64 bit quantity. These are useful for performing operations on data that is not
+in the target's native byte order.
+</p>
+
+<h5>Semantics:</h5>
+
+<p>
+The <tt>llvm.bswap.16</tt> intrinsic returns an i16 value that has the high
+and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
+intrinsic returns an i32 value that has the four bytes of the input i32
+swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
+i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt>
+intrinsic extends this concept to 64 bits.
+</p>
+</div>
<!-- _______________________________________________________________________ -->
-</ul><a name="i_call"><h4><hr size=0>'<tt>call</tt>' Instruction</h4><ul>
+<div class="doc_subsubsection">
+ <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
+</div>
+
+<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = call <ty>* <fnptrval>(<param list>)
+ declare i8 @llvm.ctpop.i8 (i8 <src>)
+ declare i16 @llvm.ctpop.i16(i16 <src>)
+ declare i32 @llvm.ctpop.i32(i32 <src>)
+ declare i64 @llvm.ctpop.i64(i64 <src>)
</pre>
<h5>Overview:</h5>
-The '<tt>call</tt>' instruction represents a simple function call.<p>
+<p>
+The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
+value.
+</p>
<h5>Arguments:</h5>
-This instruction requires several arguments:<p>
-<ol>
-
-<li>'<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>
+<p>
+The only argument is the value to be counted. The argument may be of any
+integer type. The return type must match the argument type.
+</p>
-<li>'<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>
+<h5>Semantics:</h5>
-<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.
-</ol>
+<p>
+The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
+</p>
+</div>
-<h5>Semantics:</h5>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
+</div>
-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>
+<div class="doc_text">
-<h5>Example:</h5>
+<h5>Syntax:</h5>
<pre>
- %retval = call int %test(int %argc)
- call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
-
+ declare i8 @llvm.ctlz.i8 (i8 <src>)
+ declare i16 @llvm.ctlz.i16(i16 <src>)
+ declare i32 @llvm.ctlz.i32(i32 <src>)
+ declare i64 @llvm.ctlz.i64(i64 <src>)
</pre>
-<!--
+<h5>Overview:</h5>
-<!x- *********************************************************************** -x>
-</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
-<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
-<a name="related">Related Work
-</b></font></td></tr></table><ul>
-<!x- *********************************************************************** -x>
+<p>
+The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
+leading zeros in a variable.
+</p>
+<h5>Arguments:</h5>
-Codesigned virtual machines.<p>
+<p>
+The only argument is the value to be counted. The argument may be of any
+integer type. The return type must match the argument type.
+</p>
-<dl>
-<a name="rw_safetsa">
-<dt>SafeTSA
-<DD>Description here<p>
+<h5>Semantics:</h5>
-<a name="rw_java">
-<dt><a href="http://www.javasoft.com">Java</a>
-<DD>Desciption here<p>
+<p>
+The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
+in a variable. If the src == 0 then the result is the size in bits of the type
+of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
+</p>
+</div>
-<a name="rw_net">
-<dt><a href="http://www.microsoft.com/net">Microsoft .net</a>
-<DD>Desciption here<p>
-<a name="rw_gccrtl">
-<dt><a href="http://www.math.umn.edu/systems_guide/gcc-2.95.1/gcc_15.html">GNU RTL Intermediate Representation</a>
-<DD>Desciption here<p>
-<a name="rw_ia64">
-<dt><a href="http://developer.intel.com/design/ia-64/index.htm">IA64 Architecture & Instruction Set</a>
-<DD>Desciption here<p>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
+</div>
-<a name="rw_mmix">
-<dt><a href="http://www-cs-faculty.stanford.edu/~knuth/mmix-news.html">MMIX Instruction Set</a>
-<DD>Desciption here<p>
+<div class="doc_text">
-<a name="rw_stroustrup">
-<dt><a href="http://www.research.att.com/~bs/devXinterview.html">"Interview With Bjarne Stroustrup"</a>
-<DD>This interview influenced the design and thought process behind LLVM in several ways, most notably the way that derived types are written in text format. See the question that starts with "you defined the C declarator syntax as an experiment that failed".<p>
-</dl>
+<h5>Syntax:</h5>
+<pre>
+ declare i8 @llvm.cttz.i8 (i8 <src>)
+ declare i16 @llvm.cttz.i16(i16 <src>)
+ declare i32 @llvm.cttz.i32(i32 <src>)
+ declare i64 @llvm.cttz.i64(i64 <src>)
+</pre>
-<!x- _______________________________________________________________________ -x>
-</ul><a name="rw_vectorization"><h3><hr size=0>Vectorized Architectures</h3><ul>
+<h5>Overview:</h5>
-<dl>
-<a name="rw_intel_simd">
-<dt>Intel MMX, MMX2, SSE, SSE2
-<DD>Description here<p>
+<p>
+The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
+trailing zeros.
+</p>
-<a name="rw_amd_simd">
-<dt><a href="http://www.nondot.org/~sabre/os/H1ChipFeatures/3DNow!TechnologyManual.pdf">AMD 3Dnow!, 3Dnow! 2</a>
-<DD>Desciption here<p>
+<h5>Arguments:</h5>
-<a name="rw_sun_simd">
-<dt><a href="http://www.nondot.org/~sabre/os/H1ChipFeatures/VISInstructionSetUsersManual.pdf">Sun VIS ISA</a>
-<DD>Desciption here<p>
+<p>
+The only argument is the value to be counted. The argument may be of any
+integer type. The return type must match the argument type.
+</p>
-<a name="rw_powerpc_simd">
-<dt>PowerPC Altivec
-<DD>Desciption here<p>
+<h5>Semantics:</h5>
-</dl>
+<p>
+The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
+in a variable. If the src == 0 then the result is the size in bits of the type
+of src. For example, <tt>llvm.cttz(2) = 1</tt>.
+</p>
+</div>
-more...
+<!-- ======================================================================= -->
+<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>
-<!-- *********************************************************************** -->
-</ul>
-<!-- *********************************************************************** -->
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="int_eh">Exception Handling Intrinsics</a>
+</div>
+<div class="doc_text">
+<p> The LLVM exception handling intrinsics (which all start with
+<tt>llvm.eh.</tt> prefix), are described in the <a
+href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
+Handling</a> document. </p>
+</div>
+
+<!-- *********************************************************************** -->
<hr>
-<font size=-1>
-<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
-<!-- Created: Tue Jan 23 15:19:28 CST 2001 -->
-<!-- hhmts start -->
-Last modified: Tue Sep 17 21:34:30 CDT 2002
-<!-- hhmts end -->
-</font>
-</body></html>
+<address>
+ <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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projects / oota-llvm.git / blobdiff