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| author | Chris Lattner <sabre@nondot.org> | 2003-11-25 01:02:51 +0000 |
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| committer | Chris Lattner <sabre@nondot.org> | 2003-11-25 01:02:51 +0000 |
| commit | 261efe953b14da0446ba5bcafa7f01f247106e9f (patch) | |
| tree | 319cac6bbf006cba69cff2fe107f73f55f5a5c76 /docs/LangRef.html | |
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diff --git a/docs/LangRef.html b/docs/LangRef.html index 0b639c0..05de0bd 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -1,582 +1,508 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" - "http://www.w3.org/TR/html4/strict.dtd"> +<!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> <link rel="stylesheet" href="llvm.css" type="text/css"> </head> <body> - -<div class="doc_title"> - LLVM Language Reference Manual -</div> - +<div class="doc_title"> LLVM Language Reference Manual </div> <ol> <li><a href="#abstract">Abstract</a></li> <li><a href="#introduction">Introduction</a></li> <li><a href="#identifiers">Identifiers</a></li> <li><a href="#typesystem">Type System</a> <ol> - <li><a href="#t_primitive">Primitive Types</a> - <ol> + <li><a href="#t_primitive">Primitive Types</a> + <ol> <li><a href="#t_classifications">Type Classifications</a></li> - </ol></li> + </ol> + </li> <li><a href="#t_derived">Derived Types</a> <ol> - <li><a href="#t_array" >Array Type</a></li> + <li><a href="#t_array">Array Type</a></li> <li><a href="#t_function">Function Type</a></li> <li><a href="#t_pointer">Pointer Type</a></li> - <li><a href="#t_struct" >Structure Type</a></li> - <!-- <li><a href="#t_packed" >Packed Type</a> --> - </ol></li> - </ol></li> + <li><a href="#t_struct">Structure Type</a></li> +<!-- <li><a href="#t_packed" >Packed Type</a> --> + </ol> + </li> + </ol> + </li> <li><a href="#highlevel">High Level Structure</a> <ol> <li><a href="#modulestructure">Module Structure</a></li> <li><a href="#globalvars">Global Variables</a></li> <li><a href="#functionstructure">Function Structure</a></li> - </ol></li> + </ol> + </li> <li><a href="#instref">Instruction Reference</a> <ol> <li><a href="#terminators">Terminator Instructions</a> <ol> - <li><a href="#i_ret" >'<tt>ret</tt>' Instruction</a></li> - <li><a href="#i_br" >'<tt>br</tt>' Instruction</a></li> + <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li> + <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li> <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li> <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li> - <li><a href="#i_unwind" >'<tt>unwind</tt>' Instruction</a></li> - </ol></li> + <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li> + </ol> + </li> <li><a href="#binaryops">Binary Operations</a> <ol> - <li><a href="#i_add" >'<tt>add</tt>' Instruction</a></li> - <li><a href="#i_sub" >'<tt>sub</tt>' Instruction</a></li> - <li><a href="#i_mul" >'<tt>mul</tt>' Instruction</a></li> - <li><a href="#i_div" >'<tt>div</tt>' Instruction</a></li> - <li><a href="#i_rem" >'<tt>rem</tt>' Instruction</a></li> + <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li> + <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li> + <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li> + <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li> + <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li> <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li> - </ol></li> + </ol> + </li> <li><a href="#bitwiseops">Bitwise Binary Operations</a> <ol> <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li> - <li><a href="#i_or" >'<tt>or</tt>' Instruction</a></li> + <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li> <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li> <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li> <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li> - </ol></li> + </ol> + </li> <li><a href="#memoryops">Memory Access Operations</a> <ol> - <li><a href="#i_malloc" >'<tt>malloc</tt>' Instruction</a></li> - <li><a href="#i_free" >'<tt>free</tt>' Instruction</a></li> - <li><a href="#i_alloca" >'<tt>alloca</tt>' Instruction</a></li> - <li><a href="#i_load" >'<tt>load</tt>' Instruction</a></li> - <li><a href="#i_store" >'<tt>store</tt>' Instruction</a></li> - <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li> - </ol></li> + <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li> + <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li> + <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li> + <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li> + <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li> + <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li> + </ol> + </li> <li><a href="#otherops">Other Operations</a> <ol> - <li><a href="#i_phi" >'<tt>phi</tt>' Instruction</a></li> + <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li> <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li> - <li><a href="#i_call" >'<tt>call</tt>' Instruction</a></li> + <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li> <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li> - <li><a href="#i_vaarg" >'<tt>vaarg</tt>' Instruction</a></li> + <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li> </ol> + </li> </ol> + </li> <li><a href="#intrinsics">Intrinsic Functions</a> - <ol> - <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a> <ol> - <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li> - <li><a href="#i_va_end" >'<tt>llvm.va_end</tt>' Intrinsic</a></li> - <li><a href="#i_va_copy" >'<tt>llvm.va_copy</tt>' Intrinsic</a></li> - </ol></li> - </ol></li> - + <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> + </ol> + </li> </ol> - <div class="doc_text"> - <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a> and <A href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></b><p> +<p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a> +and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></b></p> +<p> </p> </div> - <!-- *********************************************************************** --> -<div class="doc_section"> - <a name="abstract">Abstract -</div> +<div class="doc_section"> <a name="abstract">Abstract </a></div> <!-- *********************************************************************** --> - <div class="doc_text"> - -<p>This document is a reference manual for the LLVM assembly language. LLVM is -an SSA based representation that provides type safety, low-level operations, -flexibility, and the capability of representing 'all' high-level languages -cleanly. It is the common code representation used throughout all phases of the -LLVM compilation strategy.</p> - +<p>This document is a reference manual for the LLVM assembly language. +LLVM is an SSA based representation that provides type safety, +low-level operations, flexibility, and the capability of representing +'all' high-level languages cleanly. It is the common code +representation used throughout all phases of the LLVM compilation +strategy.</p> </div> - <!-- *********************************************************************** --> -<div class="doc_section"> - <a name="introduction">Introduction</a> -</div> +<div class="doc_section"> <a name="introduction">Introduction</a> </div> <!-- *********************************************************************** --> - <div class="doc_text"> - -<p>The LLVM code representation is designed to be used in three different forms: -as an in-memory compiler IR, as an on-disk bytecode representation (suitable for -fast loading by a Just-In-Time compiler), and as a human readable assembly -language representation. This allows LLVM to provide a powerful intermediate -representation for efficient compiler transformations and analysis, while -providing a natural means to debug and visualize the transformations. The three -different forms of LLVM are all equivalent. This document describes the human -readable representation and notation.</p> - -<p>The LLVM representation aims to be a light-weight and low-level while being -expressive, typed, and extensible at the same time. It aims to be a "universal -IR" of sorts, by being at a low enough level that high-level ideas may be -cleanly mapped to it (similar to how microprocessors are "universal IR's", -allowing many source languages to be mapped to them). By providing type -information, LLVM can be used as the target of optimizations: for example, -through pointer analysis, it can be proven that a C automatic variable is never -accessed outside of the current function... allowing it to be promoted to a -simple SSA value instead of a memory location.</p> - +<p>The LLVM code representation is designed to be used in three +different forms: as an in-memory compiler IR, as an on-disk bytecode +representation (suitable for fast loading by a Just-In-Time compiler), +and as a human readable assembly language representation. This allows +LLVM to provide a powerful intermediate representation for efficient +compiler transformations and analysis, while providing a natural means +to debug and visualize the transformations. The three different forms +of LLVM are all equivalent. This document describes the human readable +representation and notation.</p> +<p>The LLVM representation aims to be a light-weight and low-level +while being expressive, typed, and extensible at the same time. It +aims to be a "universal IR" of sorts, by being at a low enough level +that high-level ideas may be cleanly mapped to it (similar to how +microprocessors are "universal IR's", allowing many source languages to +be mapped to them). By providing type information, LLVM can be used as +the target of optimizations: for example, through pointer analysis, it +can be proven that a C automatic variable is never accessed outside of +the current function... allowing it to be promoted to a simple SSA +value instead of a memory location.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="wellformed">Well-Formedness</a> -</div> - +<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div> <div class="doc_text"> - -<p>It is important to note that this document describes 'well formed' LLVM -assembly language. There is a difference between what the parser accepts and -what is considered 'well formed'. For example, the following instruction is -syntactically okay, but not well formed:</p> - -<pre> - %x = <a href="#i_add">add</a> int 1, %x -</pre> - -<p>...because the definition of <tt>%x</tt> does not dominate all of its uses. -The LLVM infrastructure provides a verification pass that may be used to verify -that an LLVM module is well formed. This pass is automatically run by the -parser after parsing input assembly, and by the optimizer before it outputs -bytecode. The violations pointed out by the verifier pass indicate bugs in -transformation passes or input to the parser.</p> - -<!-- Describe the typesetting conventions here. --> - -</div> - +<p>It is important to note that this document describes 'well formed' +LLVM assembly language. There is a difference between what the parser +accepts and what is considered 'well formed'. For example, the +following instruction is syntactically okay, but not well formed:</p> +<pre> %x = <a href="#i_add">add</a> int 1, %x<br></pre> +<p>...because the definition of <tt>%x</tt> does not dominate all of +its uses. The LLVM infrastructure provides a verification pass that may +be used to verify that an LLVM module is well formed. This pass is +automatically run by the parser after parsing input assembly, and by +the optimizer before it outputs bytecode. The violations pointed out +by the verifier pass indicate bugs in transformation passes or input to +the parser.</p> +<!-- Describe the typesetting conventions here. --> </div> <!-- *********************************************************************** --> -<div class="doc_section"> - <a name="identifiers">Identifiers</a> -</div> +<div class="doc_section"> <a name="identifiers">Identifiers</a> </div> <!-- *********************************************************************** --> - <div class="doc_text"> - -<p>LLVM uses three different forms of identifiers, for different purposes:</p> - +<p>LLVM uses three different forms of identifiers, for different +purposes:</p> <ol> - - <li>Numeric constants are represented as you would expect: 12, -3 123.421, - etc. Floating point constants have an optional hexidecimal notation.</li> - - <li>Named values are represented as a string of characters with a '%' prefix. - For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual - regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'. - Identifiers which require other characters in their names can be surrounded - with quotes. In this way, anything except a <tt>"</tt> character can be used - in a name.</li> - - <li>Unnamed values are represented as an unsigned numeric value with a '%' - prefix. For example, %12, %2, %44.</li> - + <li>Numeric constants are represented as you would expect: 12, -3 +123.421, etc. Floating point constants have an optional hexidecimal +notation.</li> + <li>Named values are represented as a string of characters with a '%' +prefix. For example, %foo, %DivisionByZero, +%a.really.long.identifier. The actual regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'. +Identifiers which require other characters in their names can be +surrounded with quotes. In this way, anything except a <tt>"</tt> +character can be used in a name.</li> + <li>Unnamed values are represented as an unsigned numeric value with +a '%' prefix. For example, %12, %2, %44.</li> </ol> - -<p>LLVM requires the values start with a '%' sign for two reasons: Compilers -don't need to worry about name clashes with reserved words, and the set of -reserved words may be expanded in the future without penalty. Additionally, -unnamed identifiers allow a compiler to quickly come up with a temporary -variable without having to avoid symbol table conflicts.</p> - -<p>Reserved words in LLVM are very similar to reserved words in other languages. -There are keywords for different opcodes ('<tt><a href="#i_add">add</a></tt>', -'<tt><a href="#i_cast">cast</a></tt>', '<tt><a href="#i_ret">ret</a></tt>', -etc...), for primitive type names ('<tt><a href="#t_void">void</a></tt>', -'<tt><a href="#t_uint">uint</a></tt>', etc...), and others. These reserved -words cannot conflict with variable names, because none of them start with a '%' -character.</p> - -<p>Here is an example of LLVM code to multiply the integer variable -'<tt>%X</tt>' by 8:</p> - +<p>LLVM requires the values start with a '%' sign for two reasons: +Compilers don't need to worry about name clashes with reserved words, +and the set of reserved words may be expanded in the future without +penalty. Additionally, unnamed identifiers allow a compiler to quickly +come up with a temporary variable without having to avoid symbol table +conflicts.</p> +<p>Reserved words in LLVM are very similar to reserved words in other +languages. There are keywords for different opcodes ('<tt><a + href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a + href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a + href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', +etc...), and others. These reserved words cannot conflict with +variable names, because none of them start with a '%' character.</p> +<p>Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>' +by 8:</p> <p>The easy way:</p> - -<pre> - %result = <a href="#i_mul">mul</a> uint %X, 8 -</pre> - +<pre> %result = <a href="#i_mul">mul</a> uint %X, 8<br></pre> <p>After strength reduction:</p> - -<pre> - %result = <a href="#i_shl">shl</a> uint %X, ubyte 3 -</pre> - +<pre> %result = <a href="#i_shl">shl</a> uint %X, ubyte 3<br></pre> <p>And the hard way:</p> - -<pre> - <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i> - <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i> - %result = <a href="#i_add">add</a> uint %1, %1 -</pre> - -<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several important -lexical features of LLVM:</p> - +<pre> <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i> + <a + href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i> + %result = <a + href="#i_add">add</a> uint %1, %1<br></pre> +<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several +important lexical features of LLVM:</p> <ol> - <li>Comments are delimited with a '<tt>;</tt>' and go until the end of - line.</li> - - <li>Unnamed temporaries are created when the result of a computation is not - assigned to a named value.</li> - + <li>Comments are delimited with a '<tt>;</tt>' and go until the end +of line.</li> + <li>Unnamed temporaries are created when the result of a computation +is not assigned to a named value.</li> <li>Unnamed temporaries are numbered sequentially</li> </ol> - -<p>...and it also show a convention that we follow in this document. When -demonstrating instructions, we will follow an instruction with a comment that -defines the type and name of value produced. Comments are shown in italic -text.</p> - -<p>The one non-intuitive notation for constants is the optional hexidecimal form -of floating point constants. For example, the form '<tt>double +<p>...and it also show a convention that we follow in this document. +When demonstrating instructions, we will follow an instruction with a +comment that defines the type and name of value produced. Comments are +shown in italic text.</p> +<p>The one non-intuitive notation for constants is the optional +hexidecimal form of floating point constants. For example, the form '<tt>double 0x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double -4.5e+15</tt>' which is also supported by the parser. The only time hexadecimal -floating point constants are useful (and the only time that they are generated -by the disassembler) is when an FP constant has to be emitted that is not -representable as a decimal floating point number exactly. For example, NaN's, -infinities, and other special cases are represented in their IEEE hexadecimal -format so that assembly and disassembly do not cause any bits to change in the -constants.</p> - +4.5e+15</tt>' which is also supported by the parser. The only time +hexadecimal floating point constants are useful (and the only time that +they are generated by the disassembler) is when an FP constant has to +be emitted that is not representable as a decimal floating point number +exactly. For example, NaN's, infinities, and other special cases are +represented in their IEEE hexadecimal format so that assembly and +disassembly do not cause any bits to change in the constants.</p> </div> - <!-- *********************************************************************** --> -<div class="doc_section"> - <a name="typesystem">Type System</a> -</div> +<div class="doc_section"> <a name="typesystem">Type System</a> </div> <!-- *********************************************************************** --> - <div class="doc_text"> - <p>The LLVM type system is one of the most important features of the -intermediate representation. Being typed enables a number of optimizations to -be performed on the IR directly, without having to do extra analyses on the side -before the transformation. A strong type system makes it easier to read the -generated code and enables novel analyses and transformations that are not -feasible to perform on normal three address code representations.</p> - +intermediate representation. Being typed enables a number of +optimizations to be performed on the IR directly, without having to do +extra analyses on the side before the transformation. A strong type +system makes it easier to read the generated code and enables novel +analyses and transformations that are not feasible to perform on normal +three address code representations.</p> <!-- The written form for the type system was heavily influenced by the syntactic problems with types in the C language<sup><a -href="#rw_stroustrup">1</a></sup>.<p> --> - -</div> - +href="#rw_stroustrup">1</a></sup>.<p> --> </div> <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="t_primitive">Primitive Types</a> -</div> - +<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div> <div class="doc_text"> - -<p>The primitive types are the fundemental building blocks of the LLVM system. -The current set of primitive types are as follows:</p> - +<p>The primitive types are the fundemental building blocks of the LLVM +system. The current set of primitive types are as follows:</p> <p> <table border="0" align="center"> -<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> - -</td><td valign=top> - -<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> - -</td> -</tr> + <tbody> + <tr> + <td> + <table border="1" cellspacing="0" cellpadding="4" align="center"> + <tbody> + <tr> + <td><tt>void</tt></td> + <td>No value</td> + </tr> + <tr> + <td><tt>ubyte</tt></td> + <td>Unsigned 8 bit value</td> + </tr> + <tr> + <td><tt>ushort</tt></td> + <td>Unsigned 16 bit value</td> + </tr> + <tr> + <td><tt>uint</tt></td> + <td>Unsigned 32 bit value</td> + </tr> + <tr> + <td><tt>ulong</tt></td> + <td>Unsigned 64 bit value</td> + </tr> + <tr> + <td><tt>float</tt></td> + <td>32 bit floating point value</td> + </tr> + <tr> + <td><tt>label</tt></td> + <td>Branch destination</td> + </tr> + </tbody> + </table> + </td> + <td valign="top"> + <table border="1" cellspacing="0" cellpadding="4" align="center""> + <tbody> + <tr> + <td><tt>bool</tt></td> + <td>True or False value</td> + </tr> + <tr> + <td><tt>sbyte</tt></td> + <td>Signed 8 bit value</td> + </tr> + <tr> + <td><tt>short</tt></td> + <td>Signed 16 bit value</td> + </tr> + <tr> + <td><tt>int</tt></td> + <td>Signed 32 bit value</td> + </tr> + <tr> + <td><tt>long</tt></td> + <td>Signed 64 bit value</td> + </tr> + <tr> + <td><tt>double</tt></td> + <td>64 bit floating point value</td> + </tr> + </tbody> + </table> + </td> + </tr> + </tbody> </table> </p> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="t_classifications">Type Classifications</a> -</div> - +<div class="doc_subsubsection"> <a name="t_classifications">Type +Classifications</a> </div> <div class="doc_text"> - -<p>These different primitive types fall into a few useful classifications:</p> - +<p>These different primitive types fall into a few useful +classifications:</p> <p> <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_integer">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> + <tbody> + <tr> + <td><a name="t_signed">signed</a></td> + <td><tt>sbyte, short, int, long, float, double</tt></td> + </tr> + <tr> + <td><a name="t_unsigned">unsigned</a></td> + <td><tt>ubyte, ushort, uint, ulong</tt></td> + </tr> + <tr> + <td><a name="t_integer">integer</a></td> + <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td> + </tr> + <tr> + <td><a name="t_integral">integral</a></td> + <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td> + </tr> + <tr> + <td><a name="t_floating">floating point</a></td> + <td><tt>float, double</tt></td> + </tr> + <tr> + <td><a name="t_firstclass">first class</a></td> + <td><tt>bool, ubyte, sbyte, ushort, short,<br> +uint, int, ulong, long, float, double, <a href="#t_pointer">pointer</a></tt></td> + </tr> + </tbody> </table> </p> - -<p>The <a href="#t_firstclass">first class</a> types are perhaps the most -important. Values of these types are the only ones which can be produced by -instructions, passed as arguments, or used as operands to instructions. This -means that all structures and arrays must be manipulated either by pointer or by -component.</p> - +<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_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> - +<p>The real power in LLVM comes from the derived types in the system. +This is what allows a programmer to represent arrays, functions, +pointers, and other useful types. Note that these derived types may be +recursive: For example, it is possible to have a two dimensional array.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="t_array">Array Type</a> -</div> - +<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div> <div class="doc_text"> - <h5>Overview:</h5> - <p>The array type is a very simple derived type that arranges elements -sequentially in memory. The array type requires a size (number of elements) and -an underlying data type.</p> - +sequentially in memory. The array type requires a size (number of +elements) and an underlying data type.</p> <h5>Syntax:</h5> - -<pre> - [<# elements> x <elementtype>] -</pre> - -<p>The number of elements is a constant integer value, elementtype may be any -type with a size.</p> - +<pre> [<# elements> x <elementtype>]<br></pre> +<p>The number of elements is a constant integer value, elementtype may +be any type with a size.</p> <h5>Examples:</h5> - -<p> - <tt>[40 x int ]</tt>: Array of 40 integer values.<br> - <tt>[41 x int ]</tt>: Array of 41 integer values.<br> - <tt>[40 x uint]</tt>: Array of 40 unsigned integer values.<p> -</p> - +<p> <tt>[40 x int ]</tt>: Array of 40 integer values.<br> +<tt>[41 x int ]</tt>: Array of 41 integer values.<br> +<tt>[40 x uint]</tt>: Array of 40 unsigned integer values.</p> +<p> </p> <p>Here are some examples of multidimensional arrays:</p> - <p> <table border="0" cellpadding="0" cellspacing="0"> -<tr> - <td><tt>[3 x [4 x int]]</tt></td> - <td>: 3x4 array integer values.</td> -</tr> -<tr> - <td><tt>[12 x [10 x float]]</tt></td> - <td>: 12x10 array of single precision floating point values.</td> -</tr> -<tr> - <td><tt>[2 x [3 x [4 x uint]]]</tt></td> - <td>: 2x3x4 array of unsigned integer values.</td> -</tr> + <tbody> + <tr> + <td><tt>[3 x [4 x int]]</tt></td> + <td>: 3x4 array integer values.</td> + </tr> + <tr> + <td><tt>[12 x [10 x float]]</tt></td> + <td>: 12x10 array of single precision floating point values.</td> + </tr> + <tr> + <td><tt>[2 x [3 x [4 x uint]]]</tt></td> + <td>: 2x3x4 array of unsigned integer values.</td> + </tr> + </tbody> </table> </p> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="t_function">Function Type</a> -</div> - +<div class="doc_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 when to build virtual function tables (which are structures of pointers to -functions), for indirect function calls, and when defining a function.</p> - +<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> <h5>Syntax:</h5> - -<pre> - <returntype> (<parameter list>) -</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>, +<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> - + href="#int_varargs">variable argument handling intrinsic</a> functions.</p> <h5>Examples:</h5> - <p> <table border="0" cellpadding="0" cellspacing="0"> - -<tr> - <td><tt>int (int)</tt></td> - <td>: function taking an <tt>int</tt>, returning an <tt>int</tt></td> -</tr> -<tr> - <td><tt>float (int, int *) *</tt></td> - <td>: <a href="#t_pointer">Pointer</a> to a function that takes an - <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>, - returning <tt>float</tt>.</td> -</tr> -<tr> - <td><tt>int (sbyte *, ...)</tt></td> - <td>: A vararg function that takes at least one <a - href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C), which - returns an integer. This is the signature for <tt>printf</tt> in - LLVM.</td> -</tr> + <tbody> + <tr> + <td><tt>int (int)</tt></td> + <td>: function taking an <tt>int</tt>, returning an <tt>int</tt></td> + </tr> + <tr> + <td><tt>float (int, int *) *</tt></td> + <td>: <a href="#t_pointer">Pointer</a> to a function that takes +an <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>, +returning <tt>float</tt>.</td> + </tr> + <tr> + <td><tt>int (sbyte *, ...)</tt></td> + <td>: A vararg function that takes at least one <a + href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C), +which returns an integer. This is the signature for <tt>printf</tt> +in LLVM.</td> + </tr> + </tbody> </table> </p> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="t_struct">Structure Type</a> -</div> - +<div class="doc_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> - +<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> } -</pre> - +<pre> { <type list> }<br></pre> <h5>Examples:</h5> - <p> <table border="0" cellpadding="0" cellspacing="0"> -<tr> - <td><tt>{ int, int, int }</tt></td> - <td>: a triple of three <tt>int</tt> values</td> -</tr> -<tr> - <td><tt>{ float, int (int) * }</tt></td> - <td>: A pair, where the first element is a <tt>float</tt> and the second - element is a <a href="#t_pointer">pointer</a> to a <a - href="t_function">function</a> that takes an <tt>int</tt>, returning an - <tt>int</tt>.</td> -</tr> + <tbody> + <tr> + <td><tt>{ int, int, int }</tt></td> + <td>: a triple of three <tt>int</tt> values</td> + </tr> + <tr> + <td><tt>{ float, int (int) * }</tt></td> + <td>: A pair, where the first element is a <tt>float</tt> and the +second element is a <a href="#t_pointer">pointer</a> to a <a + href="t_function">function</a> that takes an <tt>int</tt>, returning +an <tt>int</tt>.</td> + </tr> + </tbody> </table> </p> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="t_pointer">Pointer Type</a> -</div> - +<div class="doc_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> - +<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> * -</pre> - +<pre> <type> *<br></pre> <h5>Examples:</h5> - <p> <table border="0" cellpadding="0" cellspacing="0"> -<tr> - <td><tt>[4x int]*</tt></td> - <td>: <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of four - <tt>int</tt> values</td> -</tr> -<tr> - <td><tt>int (int *) *</tt></td> - <td>: A <a href="#t_pointer">pointer</a> to a <a - href="t_function">function</a> that takes an <tt>int</tt>, returning an - <tt>int</tt>.</td> -</tr> + <tbody> + <tr> + <td><tt>[4x int]*</tt></td> + <td>: <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> +of four <tt>int</tt> values</td> + </tr> + <tr> + <td><tt>int (int *) *</tt></td> + <td>: A <a href="#t_pointer">pointer</a> to a <a + href="t_function">function</a> that takes an <tt>int</tt>, returning +an <tt>int</tt>.</td> + </tr> + </tbody> </table> </p> - </div> - -<!-- _______________________________________________________________________ --> -<!-- +<!-- _______________________________________________________________________ --><!-- <div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div> @@ -589,33 +515,20 @@ Packed types should be 'nonsaturated' because standard data types are not satura </div> ---> - - -<!-- *********************************************************************** --> -<div class="doc_section"> - <a name="highlevel">High Level Structure</a> -</div> -<!-- *********************************************************************** --> - - -<!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="modulestructure">Module Structure</a> -</div> - +--><!-- *********************************************************************** --> +<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div> +<!-- *********************************************************************** --><!-- ======================================================================= --> +<div class="doc_subsection"> <a name="modulestructure">Module Structure</a> </div> <div class="doc_text"> - -<p>LLVM programs are composed of "Module"s, each of which is a translation unit -of the input programs. Each module consists of functions, global variables, and -symbol table entries. Modules may be combined together with the LLVM linker, -which merges function (and global variable) definitions, resolves forward -declarations, and merges symbol table entries. Here is an example of the "hello -world" module:</p> - -<pre> -<i>; Declare the string constant as a global constant...</i> -<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i> +<p>LLVM programs are composed of "Module"s, each of which is a +translation unit of the input programs. Each module consists of +functions, global variables, and symbol table entries. Modules may be +combined together with the LLVM linker, which merges function (and +global variable) definitions, resolves forward declarations, and merges +symbol table entries. Here is an example of the "hello world" module:</p> +<pre><i>; Declare the string constant as a global constant...</i> +<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a + href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i> <i>; External declaration of the puts function</i> <a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i> @@ -623,307 +536,223 @@ world" module:</p> <i>; Definition of main function</i> int %main() { <i>; int()* </i> <i>; Convert [13x sbyte]* to sbyte *...</i> - %cast210 = <a href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i> + %cast210 = <a + href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i> <i>; Call puts function to write out the string to stdout...</i> - <a href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i> - <a href="#i_ret">ret</a> int 0 -} -</pre> - -<p>This example is made up of a <a href="#globalvars">global variable</a> named -"<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>" function, and a -<a href="#functionstructure">function definition</a> for "<tt>main</tt>".</p> - -<a name="linkage"> -In general, a module is made up of a list of global values, where both functions -and global variables are global values. Global values are represented by a -pointer to a memory location (in this case, a pointer to an array of char, and a -pointer to a function), and have one of the following linkage types:<p> - + <a + href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i> + <a + href="#i_ret">ret</a> int 0<br>}<br></pre> +<p>This example is made up of a <a href="#globalvars">global variable</a> +named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>" +function, and a <a href="#functionstructure">function definition</a> +for "<tt>main</tt>".</p> +<a name="linkage"> In general, a module is made up of a list of global +values, where both functions and global variables are global values. +Global values are represented by a pointer to a memory location (in +this case, a pointer to an array of char, and a pointer to a function), +and have one of the following linkage types:</a> +<p> </p> <dl> -<a name="linkage_internal"> -<dt><tt><b>internal</b></tt> - -<dd>Global values with internal linkage are only directly accessible by objects -in the current module. In particular, linking code into a module with an -internal global value may cause the internal to be renamed as necessary to avoid -collisions. Because the symbol is internal to the module, all references can be -updated. This corresponds to the notion of the '<tt>static</tt>' keyword in C, -or the idea of "anonymous namespaces" in C++.<p> - -<a name="linkage_linkonce"> -<dt><tt><b>linkonce</b></tt>: - -<dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with -the twist that linking together two modules defining the same <tt>linkonce</tt> -globals will cause one of the globals to be discarded. This is typically used -to implement inline functions. Unreferenced <tt>linkonce</tt> globals are -allowed to be discarded.<p> - -<a name="linkage_weak"> -<dt><tt><b>weak</b></tt>: - -<dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage, -except that unreferenced <tt>weak</tt> globals may not be discarded. This is -used to implement constructs in C such as "<tt>int X;</tt>" at global scope.<p> - -<a name="linkage_appending"> -<dt><tt><b>appending</b></tt>: - -<dd>"<tt>appending</tt>" linkage may only be applied to global variables of -pointer -to array type. When two global variables with appending linkage are linked -together, the two global arrays are appended together. This is the LLVM, -typesafe, equivalent of having the system linker append together "sections" with -identical names when .o files are linked.<p> - -<a name="linkage_external"> -<dt><tt><b>externally visible</b></tt>: - -<dd>If none of the above identifiers are used, the global is externally visible, -meaning that it participates in linkage and can be used to resolve external -symbol references.<p> - -</dl><p> - -<p>For example, since the "<tt>.LC0</tt>" variable is defined to be internal, if -another module defined a "<tt>.LC0</tt>" variable and was linked with this one, -one of the two would be renamed, preventing a collision. Since "<tt>main</tt>" -and "<tt>puts</tt>" are external (i.e., lacking any linkage declarations), they -are accessible outside of the current module. It is illegal for a function -<i>declaration</i> to have any linkage type other than "externally visible".</p> - + <a name="linkage_internal"> <dt><tt><b>internal</b></tt> </dt> + <dd>Global values with internal linkage are only directly accessible +by objects in the current module. In particular, linking code into a +module with an internal global value may cause the internal to be +renamed as necessary to avoid collisions. Because the symbol is +internal to the module, all references can be updated. This +corresponds to the notion of the '<tt>static</tt>' keyword in C, or the +idea of "anonymous namespaces" in C++. + <p> </p> + </dd> + </a><a name="linkage_linkonce"> <dt><tt><b>linkonce</b></tt>: </dt> + <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> +linkage, with the twist that linking together two modules defining the +same <tt>linkonce</tt> globals will cause one of the globals to be +discarded. This is typically used to implement inline functions. +Unreferenced <tt>linkonce</tt> globals are allowed to be discarded. + <p> </p> + </dd> + </a><a name="linkage_weak"> <dt><tt><b>weak</b></tt>: </dt> + <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> +linkage, except that unreferenced <tt>weak</tt> globals may not be +discarded. This is used to implement constructs in C such as "<tt>int +X;</tt>" at global scope. + <p> </p> + </dd> + </a><a name="linkage_appending"> <dt><tt><b>appending</b></tt>: </dt> + <dd>"<tt>appending</tt>" linkage may only be applied to global +variables of pointer to array type. When two global variables with +appending linkage are linked together, the two global arrays are +appended together. This is the LLVM, typesafe, equivalent of having +the system linker append together "sections" with identical names when +.o files are linked. + <p> </p> + </dd> + </a><a name="linkage_external"> <dt><tt><b>externally visible</b></tt>:</dt> + <dd>If none of the above identifiers are used, the global is +externally visible, meaning that it participates in linkage and can be +used to resolve external symbol references. + <p> </p> + </dd> + </a> +</dl> +<p> </p> +<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>" +variable is defined to be internal, if another module defined a "<tt>.LC0</tt>" +variable and was linked with this one, one of the two would be renamed, +preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are +external (i.e., lacking any linkage declarations), they are accessible +outside of the current module. It is illegal for a function <i>declaration</i> +to have any linkage type other than "externally visible".</a></p> </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="globalvars">Global Variables</a> -</div> - +<div class="doc_subsection"> <a name="globalvars">Global Variables</a> </div> <div class="doc_text"> - -<p>Global variables define regions of memory allocated at compilation time -instead of run-time. Global variables may optionally be initialized. A -variable may be defined as a global "constant", which indicates that the -contents of the variable will never be modified (opening options for -optimization). Constants must always have an initial value.</p> - -<p>As SSA values, global variables define pointer values that are in scope -(i.e. they dominate) for all basic blocks in the program. Global variables -always define a pointer to their "content" type because they describe a region -of memory, and all memory objects in LLVM are accessed through pointers.</p> - +<p>Global variables define regions of memory allocated at compilation +time instead of run-time. Global variables may optionally be +initialized. A variable may be defined as a global "constant", which +indicates that the contents of the variable will never be modified +(opening options for optimization). Constants must always have an +initial value.</p> +<p>As SSA values, global variables define pointer values that are in +scope (i.e. they dominate) for all basic blocks in the program. Global +variables always define a pointer to their "content" type because they +describe a region of memory, and all memory objects in LLVM are +accessed through pointers.</p> </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="functionstructure">Functions</a> -</div> - +<div class="doc_subsection"> <a name="functionstructure">Functions</a> </div> <div class="doc_text"> - -<p>LLVM function definitions are composed of a (possibly empty) argument list, -an opening curly brace, a list of basic blocks, and a closing curly brace. LLVM -function declarations are defined with the "<tt>declare</tt>" keyword, a -function name, and a function signature.</p> - -<p>A function definition contains a list of basic blocks, forming the CFG for -the function. Each basic block may optionally start with a label (giving the -basic block a symbol table entry), contains a list of instructions, and ends -with a <a href="#terminators">terminator</a> instruction (such as a branch or -function return).</p> - -<p>The first basic block in program is special in two ways: it is immediately -executed on entrance to the function, and it is not allowed to have predecessor -basic blocks (i.e. there can not be any branches to the entry block of a -function). Because the block can have no predecessors, it also cannot have any -<a href="#i_phi">PHI nodes</a>.</p> - +<p>LLVM function definitions are composed of a (possibly empty) +argument list, an opening curly brace, a list of basic blocks, and a +closing curly brace. LLVM function declarations are defined with the "<tt>declare</tt>" +keyword, a function name, and a function signature.</p> +<p>A function definition contains a list of basic blocks, forming the +CFG for the function. Each basic block may optionally start with a +label (giving the basic block a symbol table entry), contains a list of +instructions, and ends with a <a href="#terminators">terminator</a> +instruction (such as a branch or function return).</p> +<p>The first basic block in program is special in two ways: it is +immediately executed on entrance to the function, and it is not allowed +to have predecessor basic blocks (i.e. there can not be any branches to +the entry block of a function). Because the block can have no +predecessors, it also cannot have any <a href="#i_phi">PHI nodes</a>.</p> </div> - <!-- *********************************************************************** --> -<div class="doc_section"> - <a name="instref">Instruction Reference</a> -</div> +<div class="doc_section"> <a name="instref">Instruction Reference</a> </div> <!-- *********************************************************************** --> - <div class="doc_text"> - -<p>The LLVM instruction set consists of several different classifications of -instructions: <a href="#terminators">terminator instructions</a>, <a -href="#binaryops">binary instructions</a>, <a href="#memoryops">memory -instructions</a>, and <a href="#otherops">other instructions</a>.</p> - +<p>The LLVM instruction set consists of several different +classifications of instructions: <a href="#terminators">terminator +instructions</a>, <a href="#binaryops">binary instructions</a>, <a + href="#memoryops">memory instructions</a>, and <a href="#otherops">other +instructions</a>.</p> </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="terminators">Terminator Instructions</a> -</div> - +<div class="doc_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>As mentioned <a href="#functionstructure">previously</a>, every +basic block in a program ends with a "Terminator" instruction, which +indicates which block should be executed after the current block is +finished. These terminator instructions typically yield a '<tt>void</tt>' +value: they produce control flow, not values (the one exception being +the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p> <p>There are five different terminator instructions: the '<a -href="#i_ret"><tt>ret</tt></a>' instruction, the '<a -href="#i_br"><tt>br</tt></a>' instruction, the '<a -href="#i_switch"><tt>switch</tt></a>' instruction, the '<a -href="#i_invoke"><tt>invoke</tt></a>' instruction, and the '<a -href="#i_unwind"><tt>unwind</tt></a>' instruction.</p> - + href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>' +instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction, +the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, and the '<a + href="#i_unwind"><tt>unwind</tt></a>' instruction.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_ret">'<tt>ret</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> -<pre> - ret <type> <value> <i>; Return a value from a non-void function</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> - -<p>The '<tt>ret</tt>' instruction is used to return control flow (and a value) -from a function, back to the caller.</p> - -<p>There are two forms of the '<tt>ret</tt>' instructruction: one that returns a -value and then causes control flow, and one that just causes control flow to -occur.</p> - +<p>The '<tt>ret</tt>' instruction is used to return control flow (and a +value) from a function, back to the caller.</p> +<p>There are two forms of the '<tt>ret</tt>' instructruction: one that +returns a value and then causes control flow, and one that just causes +control flow to occur.</p> <h5>Arguments:</h5> - -<p>The '<tt>ret</tt>' instruction may return any '<a href="#t_firstclass">first -class</a>' type. Notice that a function is not <a href="#wellformed">well -formed</a> if there exists a '<tt>ret</tt>' instruction inside of the function -that returns a value that does not match the return type of the function.</p> - +<p>The '<tt>ret</tt>' instruction may return any '<a + href="#t_firstclass">first class</a>' type. Notice that a function is +not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>' +instruction inside of the function that returns a value that does not +match the return type of the function.</p> <h5>Semantics:</h5> - -<p>When the '<tt>ret</tt>' instruction is executed, control flow returns back to -the calling function's context. If the caller is a "<a -href="#i_call"><tt>call</tt></a> instruction, execution continues at the -instruction after the call. If the caller was an "<a -href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues at the -beginning "normal" of the destination block. If the instruction returns a -value, that value shall set the call or invoke instruction's return value.</p> - +<p>When the '<tt>ret</tt>' instruction is executed, control flow +returns back to the calling function's context. If the caller is a "<a + href="#i_call"><tt>call</tt></a> instruction, execution continues at +the instruction after the call. If the caller was an "<a + href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues +at the beginning "normal" of the destination block. If the instruction +returns a value, that value shall set the call or invoke instruction's +return value.</p> <h5>Example:</h5> -<pre> - ret int 5 <i>; Return an integer value of 5</i> +<pre> ret int 5 <i>; Return an integer value of 5</i> ret void <i>; Return from a void function</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_br">'<tt>br</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - br bool <cond>, label <iftrue>, label <iffalse> - br label <dest> <i>; Unconditional branch</i> +<pre> br bool <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> - +<p>The '<tt>br</tt>' instruction is used to cause control flow to +transfer to a different basic block in the current function. There are +two forms of this instruction, corresponding to a conditional branch +and an unconditional branch.</p> <h5>Arguments:</h5> - -<p>The conditional branch form of the '<tt>br</tt>' instruction takes a single -'<tt>bool</tt>' value and two '<tt>label</tt>' values. The unconditional form -of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>' value as a -target.</p> - +<p>The conditional branch form of the '<tt>br</tt>' instruction takes a +single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The +unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>' +value as a target.</p> <h5>Semantics:</h5> - -<p>Upon execution of a conditional '<tt>br</tt>' instruction, the -'<tt>bool</tt>' argument is evaluated. If the value is <tt>true</tt>, control -flows to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is -<tt>false</tt>, control flows to the '<tt>iffalse</tt>' <tt>label</tt> -argument.</p> - +<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>' +argument is evaluated. If the value is <tt>true</tt>, control flows +to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>, +control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p> <h5>Example:</h5> - -<pre> -Test: - %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> - +<pre>Test:<br> %cond = <a href="#i_setcc">seteq</a> int %a, %b<br> br bool %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a + href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_switch">'<tt>switch</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_switch">'<tt>switch</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - switch uint <value>, label <defaultdest> [ int <val>, label &dest>, ... ] -</pre> - +<pre> switch uint <value>, label <defaultdest> [ int <val>, label &dest>, ... ]<br></pre> <h5>Overview:</h5> - -<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of -several different places. It is a generalization of the '<tt>br</tt>' +<p>The '<tt>switch</tt>' instruction is used to transfer control flow +to one of several different places. It is a generalization of the '<tt>br</tt>' instruction, allowing a branch to occur to one of many possible destinations.</p> - <h5>Arguments:</h5> - <p>The '<tt>switch</tt>' instruction uses three parameters: a '<tt>uint</tt>' -comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and -an array of pairs of comparison value constants and '<tt>label</tt>'s.</p> - +comparison value '<tt>value</tt>', a default '<tt>label</tt>' +destination, and an array of pairs of comparison value constants and '<tt>label</tt>'s.</p> <h5>Semantics:</h5> - -<p>The <tt>switch</tt> instruction specifies a table of values and destinations. -When the '<tt>switch</tt>' instruction is executed, this table is searched for -the given value. If the value is found, the corresponding destination is -branched to, otherwise the default value it transfered to.</p> - +<p>The <tt>switch</tt> instruction specifies a table of values and +destinations. When the '<tt>switch</tt>' instruction is executed, this +table is searched for the given value. If the value is found, the +corresponding destination is branched to, otherwise the default value +it transfered to.</p> <h5>Implementation:</h5> - -<p>Depending on properties of the target machine and the particular -<tt>switch</tt> instruction, this instruction may be code generated as a series -of chained conditional branches, or with a lookup table.</p> - +<p>Depending on properties of the target machine and the particular <tt>switch</tt> +instruction, this instruction may be code generated as a series of +chained conditional branches, or with a lookup table.</p> <h5>Example:</h5> - -<pre> - <i>; Emulate a conditional br instruction</i> - %Val = <a href="#i_cast">cast</a> bool %value to uint - switch uint %Val, label %truedest [int 0, label %falsedest ] - - <i>; Emulate an unconditional br instruction</i> +<pre> <i>; Emulate a conditional br instruction</i> + %Val = <a + href="#i_cast">cast</a> bool %value to uint<br> switch uint %Val, label %truedest [int 0, label %falsedest ]<br><br> <i>; Emulate an unconditional br instruction</i> switch uint 0, label %dest [ ] <i>; Implement a jump table:</i> @@ -931,934 +760,647 @@ of chained conditional branches, or with a lookup table.</p> int 1, label %onone, int 2, label %ontwo ] </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_invoke">'<tt>invoke</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_invoke">'<tt>invoke</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = invoke <ptr to function ty> %<function ptr val>(<function args>) - to label <normal label> except label <exception label> -</pre> - +<pre> <result> = invoke <ptr to function ty> %<function ptr val>(<function args>)<br> to label <normal label> except label <exception label><br></pre> <h5>Overview:</h5> - -<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified -function, with the possibility of control flow transfer to either the -'<tt>normal</tt>' <tt>label</tt> label or the '<tt>exception</tt>' -<tt>label</tt>. If the callee function returns with the "<tt><a -href="#i_ret">ret</a></tt>" instruction, control flow will return to the -"normal" label. If the callee (or any indirect callees) returns with the "<a -href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted, and -continued at the dynamically nearest "except" label.</p> - +<p>The '<tt>invoke</tt>' instruction causes control to transfer to a +specified function, with the possibility of control flow transfer to +either the '<tt>normal</tt>' <tt>label</tt> label or the '<tt>exception</tt>'<tt>label</tt>. +If the callee function returns with the "<tt><a href="#i_ret">ret</a></tt>" +instruction, control flow will return to the "normal" label. If the +callee (or any indirect callees) returns with the "<a href="#i_unwind"><tt>unwind</tt></a>" +instruction, control is interrupted, and continued at the dynamically +nearest "except" label.</p> <h5>Arguments:</h5> - <p>This instruction requires several arguments:</p> - <ol> - -<li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to -function value being invoked. In most cases, this is a direct function -invocation, but indirect <tt>invoke</tt>s are just as possible, branching off -an arbitrary pointer to function value. - -<li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a -function to be invoked. - -<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>'<tt>normal label</tt>': the label reached when the called function executes -a '<tt><a href="#i_ret">ret</a></tt>' instruction. - -<li>'<tt>exception label</tt>': the label reached when a callee returns with the -<a href="#i_unwind"><tt>unwind</tt></a> instruction. + <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> - + href="#i_call">call</a></tt>' instruction in most regards. The +primary difference is that it establishes an association with a label, +which is used by the runtime library to unwind the stack.</p> +<p>This instruction is used in languages with destructors to ensure +that proper cleanup is performed in the case of either a <tt>longjmp</tt> +or a thrown exception. Additionally, this is important for +implementation of '<tt>catch</tt>' clauses in high-level languages that +support them.</p> <h5>Example:</h5> - -<pre> - %retval = invoke int %Test(int 15) - to label %Continue - except label %TestCleanup <i>; {int}:retval set</i> +<pre> %retval = invoke int %Test(int 15)<br> to label %Continue<br> except label %TestCleanup <i>; {int}:retval set</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_unwind">'<tt>unwind</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - unwind -</pre> - +<pre> unwind<br></pre> <h5>Overview:</h5> - -<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow -at the first callee in the dynamic call stack which used an <a -href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is -primarily used to implement exception handling.</p> - +<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> - +<p>The '<tt>unwind</tt>' intrinsic causes execution of the current +function to immediately halt. The dynamic call stack is then searched +for the first <a href="#i_invoke"><tt>invoke</tt></a> instruction on +the call stack. Once found, execution continues at the "exceptional" +destination block specified by the <tt>invoke</tt> instruction. If +there is no <tt>invoke</tt> instruction in the dynamic call chain, +undefined behavior results.</p> </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="binaryops">Binary Operations</a> -</div> - +<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div> <div class="doc_text"> - -<p>Binary operators are used to do most of the computation in a program. They -require two operands, execute an operation on them, and produce a single value. -The result value of a binary operator is not necessarily the same type as its -operands.</p> - +<p>Binary operators are used to do most of the computation in a +program. They require two operands, execute an operation on them, and +produce a single value. The result value of a binary operator is not +necessarily the same type as its operands.</p> <p>There are several different binary operators:</p> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_add">'<tt>add</tt>' Instruction</a> -</div> - +<div class="doc_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> <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. Both arguments must have identical types.</p> - + href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> +values. Both arguments must have identical types.</p> <h5>Semantics:</h5> - <p>The value produced is the integer or floating point sum of the two operands.</p> - <h5>Example:</h5> - -<pre> - <result> = add int 4, %var <i>; yields {int}:result = 4 + %var</i> +<pre> <result> = add int 4, %var <i>; yields {int}:result = 4 + %var</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_sub">'<tt>sub</tt>' Instruction</a> -</div> - +<div class="doc_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> <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> - +<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>' +instruction present in most other intermediate representations.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>sub</tt>' instruction must be either <a -href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> -values. Both arguments must have identical types.</p> - + href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> +values. Both arguments must have identical types.</p> <h5>Semantics:</h5> - -<p>The value produced is the integer or floating point difference of the two -operands.</p> - +<p>The value produced is the integer or floating point difference of +the two operands.</p> <h5>Example:</h5> - -<pre> - <result> = sub int 4, %var <i>; yields {int}:result = 4 - %var</i> +<pre> <result> = sub int 4, %var <i>; yields {int}:result = 4 - %var</i> <result> = sub int 0, %val <i>; yields {int}:result = -%var</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_mul">'<tt>mul</tt>' Instruction</a> -</div> - +<div class="doc_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> <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> - +<p>The '<tt>mul</tt>' instruction returns the product of its two +operands.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>mul</tt>' instruction must be either <a -href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> -values. Both arguments must have identical types.</p> - + href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> +values. Both arguments must have identical types.</p> <h5>Semantics:</h5> - -<p>The value produced is the integer or floating point product of the two -operands.</p> - -<p>There is no signed vs unsigned multiplication. The appropriate action is -taken based on the type of the operand.</p> - +<p>The value produced is the integer or floating point product of the +two operands.</p> +<p>There is no signed vs unsigned multiplication. The appropriate +action is taken based on the type of the operand.</p> <h5>Example:</h5> - -<pre> - <result> = mul int 4, %var <i>; yields {int}:result = 4 * %var</i> +<pre> <result> = mul int 4, %var <i>; yields {int}:result = 4 * %var</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_div">'<tt>div</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = div <ty> <var1>, <var2> <i>; yields {ty}:result</i> +<pre> <result> = div <ty> <var1>, <var2> <i>; yields {ty}:result</i> </pre> - <h5>Overview:</h5> - -<p>The '<tt>div</tt>' instruction returns the quotient of its two operands.</p> - +<p>The '<tt>div</tt>' instruction returns the quotient of its two +operands.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>div</tt>' instruction must be either <a -href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> -values. Both arguments must have identical types.</p> - + href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> +values. Both arguments must have identical types.</p> <h5>Semantics:</h5> - -<p>The value produced is the integer or floating point quotient of the two -operands.</p> - +<p>The value produced is the integer or floating point quotient of the +two operands.</p> <h5>Example:</h5> - -<pre> - <result> = div int 4, %var <i>; yields {int}:result = 4 / %var</i> +<pre> <result> = div int 4, %var <i>; yields {int}:result = 4 / %var</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_rem">'<tt>rem</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = rem <ty> <var1>, <var2> <i>; yields {ty}:result</i> +<pre> <result> = rem <ty> <var1>, <var2> <i>; yields {ty}:result</i> </pre> - <h5>Overview:</h5> - -<p>The '<tt>rem</tt>' instruction returns the remainder from the division of its -two operands.</p> - +<p>The '<tt>rem</tt>' instruction returns the remainder from the +division of its two operands.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>rem</tt>' instruction must be either <a -href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> -values. Both arguments must have identical types.</p> - + href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> +values. Both arguments must have identical types.</p> <h5>Semantics:</h5> - -<p>This returns the <i>remainder</i> of a division (where the result has the -same sign as the divisor), not the <i>modulus</i> (where the result has the same -sign as the dividend) of a value. For more information about the difference, -see: <a href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The Math -Forum</a>.</p> - +<p>This returns the <i>remainder</i> of a division (where the result +has the same sign as the divisor), not the <i>modulus</i> (where the +result has the same sign as the dividend) of a value. For more +information about the difference, see: <a + href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The +Math Forum</a>.</p> <h5>Example:</h5> - -<pre> - <result> = rem int 4, %var <i>; yields {int}:result = 4 % %var</i> +<pre> <result> = rem int 4, %var <i>; yields {int}:result = 4 % %var</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a> -</div> - +<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>' +Instructions</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = seteq <ty> <var1>, <var2> <i>; yields {bool}:result</i> +<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> - -<h5>Overview:</h5> - -<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean value -based on a comparison of their two operands.</p> - -<h5>Arguments:</h5> - -<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must be of <a -href="#t_firstclass">first class</a> type (it is not possible to compare -'<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>' or '<tt>void</tt>' -values, etc...). Both arguments must have identical types.</p> - +<h5>Overview:</h5> +<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean +value based on a comparison of their two operands.</p> +<h5>Arguments:</h5> +<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must +be of <a href="#t_firstclass">first class</a> type (it is not possible +to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>' +or '<tt>void</tt>' values, etc...). Both arguments must have identical +types.</p> <h5>Semantics:</h5> - -<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value -if both operands are equal.<br> - -The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if -both operands are unequal.<br> - -The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if -the first operand is less than the second operand.<br> - -The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if -the first operand is greater than the second operand.<br> - -The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if -the first operand is less than or equal to the second operand.<br> - -The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if -the first operand is greater than or equal to the second operand.</p> - +<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' +value if both operands are equal.<br> +The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' +value if both operands are unequal.<br> +The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' +value if the first operand is less than the second operand.<br> +The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' +value if the first operand is greater than the second operand.<br> +The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' +value if the first operand is less than or equal to the second operand.<br> +The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' +value if the first operand is greater than or equal to the second +operand.</p> <h5>Example:</h5> - -<pre> - <result> = seteq int 4, 5 <i>; yields {bool}:result = false</i> +<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> </pre> - </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="bitwiseops">Bitwise Binary Operations</a> -</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> - +<p>Bitwise binary operators are used to do various forms of +bit-twiddling in a program. They are generally very efficient +instructions, and can commonly be strength reduced from other +instructions. They require two operands, execute an operation on them, +and produce a single value. The resulting value of the bitwise binary +operators is always the same type as its first operand.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_and">'<tt>and</tt>' Instruction</a> -</div> - +<div class="doc_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> <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> - +<p>The '<tt>and</tt>' instruction returns the bitwise logical and of +its two operands.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>and</tt>' instruction must be <a -href="#t_integral">integral</a> values. Both arguments must have identical -types.</p> - + href="#t_integral">integral</a> values. Both arguments must have +identical types.</p> <h5>Semantics:</h5> - <p>The truth table used for the '<tt>and</tt>' instruction is:</p> - -<p> +<p> </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> - + <tbody> + <tr> + <td>In0</td> + <td>In1</td> + <td>Out</td> + </tr> + <tr> + <td>0</td> + <td>0</td> + <td>0</td> + </tr> + <tr> + <td>0</td> + <td>1</td> + <td>0</td> + </tr> + <tr> + <td>1</td> + <td>0</td> + <td>0</td> + </tr> + <tr> + <td>1</td> + <td>1</td> + <td>1</td> + </tr> + </tbody> +</table> +</center> <h5>Example:</h5> - -<pre> - <result> = and int 4, %var <i>; yields {int}:result = 4 & %var</i> +<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> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_or">'<tt>or</tt>' Instruction</a> -</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> <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>Overview:</h5> +<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive +or of its two operands.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>or</tt>' instruction must be <a -href="#t_integral">integral</a> values. Both arguments must have identical -types.</p> - + href="#t_integral">integral</a> values. Both arguments must have +identical types.</p> <h5>Semantics:</h5> - <p>The truth table used for the '<tt>or</tt>' instruction is:</p> - -<p> -<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> </p> +<center> +<table border="1" cellspacing="0" cellpadding="4"> + <tbody> + <tr> + <td>In0</td> + <td>In1</td> + <td>Out</td> + </tr> + <tr> + <td>0</td> + <td>0</td> + <td>0</td> + </tr> + <tr> + <td>0</td> + <td>1</td> + <td>1</td> + </tr> + <tr> + <td>1</td> + <td>0</td> + <td>1</td> + </tr> + <tr> + <td>1</td> + <td>1</td> + <td>1</td> + </tr> + </tbody> +</table> +</center> <h5>Example:</h5> - -<pre> - <result> = or int 4, %var <i>; yields {int}:result = 4 | %var</i> +<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> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_xor">'<tt>xor</tt>' Instruction</a> -</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> <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> - +<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive +or of its two operands. The <tt>xor</tt> is used to implement the +"one's complement" operation, which is the "~" operator in C.</p> <h5>Arguments:</h5> - <p>The two arguments to the '<tt>xor</tt>' instruction must be <a -href="#t_integral">integral</a> values. Both arguments must have identical -types.</p> - + href="#t_integral">integral</a> values. Both arguments must have +identical types.</p> <h5>Semantics:</h5> - <p>The truth table used for the '<tt>xor</tt>' instruction is:</p> - -<p> -<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> - +<p> </p> +<center> +<table border="1" cellspacing="0" cellpadding="4"> + <tbody> + <tr> + <td>In0</td> + <td>In1</td> + <td>Out</td> + </tr> + <tr> + <td>0</td> + <td>0</td> + <td>0</td> + </tr> + <tr> + <td>0</td> + <td>1</td> + <td>1</td> + </tr> + <tr> + <td>1</td> + <td>0</td> + <td>1</td> + </tr> + <tr> + <td>1</td> + <td>1</td> + <td>0</td> + </tr> + </tbody> +</table> +</center> +<p> </p> <h5>Example:</h5> - -<pre> - <result> = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i> +<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> <result> = xor int %V, -1 <i>; yields {int}:result = ~%V</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_shl">'<tt>shl</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = shl <ty> <var1>, ubyte <var2> <i>; yields {ty}:result</i> +<pre> <result> = shl <ty> <var1>, ubyte <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> - +<p>The '<tt>shl</tt>' instruction returns the first operand shifted to +the left a specified number of bits.</p> <h5>Arguments:</h5> - <p>The first argument to the '<tt>shl</tt>' instruction must be an <a -href="#t_integer">integer</a> type. The second argument must be an -'<tt>ubyte</tt>' type.</p> - + href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>' +type.</p> <h5>Semantics:</h5> - <p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p> - <h5>Example:</h5> - -<pre> - <result> = shl int 4, ubyte %var <i>; yields {int}:result = 4 << %var</i> +<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> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_shr">'<tt>shr</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = shr <ty> <var1>, ubyte <var2> <i>; yields {ty}:result</i> +<pre> <result> = shr <ty> <var1>, ubyte <var2> <i>; yields {ty}:result</i> </pre> - <h5>Overview:</h5> - -<p>The '<tt>shr</tt>' instruction returns the first operand shifted to the right -a specified number of bits.</p> - +<p>The '<tt>shr</tt>' instruction returns the first operand shifted to +the right a specified number of bits.</p> <h5>Arguments:</h5> - <p>The first argument to the '<tt>shr</tt>' instruction must be an <a -href="#t_integer">integer</a> type. The second argument must be an -'<tt>ubyte</tt>' type.</p> - + href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>' +type.</p> <h5>Semantics:</h5> - -<p>If the first argument is a <a href="#t_signed">signed</a> type, the most -significant bit is duplicated in the newly free'd bit positions. If the first -argument is unsigned, zero bits shall fill the empty positions.</p> - +<p>If the first argument is a <a href="#t_signed">signed</a> type, the +most significant bit is duplicated in the newly free'd bit positions. +If the first argument is unsigned, zero bits shall fill the empty +positions.</p> <h5>Example:</h5> - -<pre> - <result> = shr int 4, ubyte %var <i>; yields {int}:result = 4 >> %var</i> +<pre> <result> = shr int 4, ubyte %var <i>; yields {int}:result = 4 >> %var</i> <result> = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i> <result> = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i> <result> = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i> <result> = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i> </pre> - </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="memoryops">Memory Access Operations</div> -</div> - +<div class="doc_subsection"> <a name="memoryops">Memory Access +Operations</a></div> <div class="doc_text"> - -<p>A key design point of an SSA-based representation is how it represents -memory. In LLVM, no memory locations are in SSA form, which makes things very -simple. This section describes how to read, write, allocate and free memory in -LLVM.</p> - +<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_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = malloc <type>, uint <NumElements> <i>; yields {type*}:result</i> +<pre> <result> = malloc <type>, uint <NumElements> <i>; yields {type*}:result</i> <result> = malloc <type> <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> - +<p>The '<tt>malloc</tt>' instruction allocates memory from the system +heap and returns a pointer to it.</p> <h5>Arguments:</h5> - -<p>The the '<tt>malloc</tt>' instruction allocates -<tt>sizeof(<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> - +<p>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> <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> - +<p>Memory is allocated using the system "<tt>malloc</tt>" function, and +a pointer is returned.</p> <h5>Example:</h5> +<pre> %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i> -<pre> - %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i> - - %size = <a href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i> + %size = <a + href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i> %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i> %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_free">'<tt>free</tt>' Instruction</a> -</div> - +<div class="doc_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> 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> - +<p>The '<tt>free</tt>' instruction returns memory back to the unused +memory heap, to be reallocated in the future.</p> +<p> </p> <h5>Arguments:</h5> - -<p>'<tt>value</tt>' shall be a pointer value that points to a value that was -allocated with the '<tt><a href="#i_malloc">malloc</a></tt>' instruction.</p> - +<p>'<tt>value</tt>' shall be a pointer value that points to a value +that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>' +instruction.</p> <h5>Semantics:</h5> - -<p>Access to the memory pointed to by the pointer is not longer defined after -this instruction executes.</p> - +<p>Access to the memory pointed to by the pointer is not longer defined +after this instruction executes.</p> <h5>Example:</h5> -<pre> - %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i> +<pre> %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i> free [4 x ubyte]* %array </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_alloca">'<tt>alloca</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = alloca <type>, uint <NumElements> <i>; yields {type*}:result</i> +<pre> <result> = alloca <type>, uint <NumElements> <i>; yields {type*}:result</i> <result> = alloca <type> <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> - +<p>The '<tt>alloca</tt>' instruction allocates memory on the current +stack frame of the procedure that is live until the current function +returns to its caller.</p> <h5>Arguments:</h5> - -<p>The the '<tt>alloca</tt>' instruction allocates -<tt>sizeof(<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> - +<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> <p>'<tt>type</tt>' may be any sized type.</p> - <h5>Semantics:</h5> - -<p>Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d memory is -automatically released when the function returns. The '<tt>alloca</tt>' -instruction is commonly used to represent automatic variables that must have an -address available. When the function returns (either with the <tt><a -href="#i_ret">ret</a></tt> or <tt><a href="#i_invoke">invoke</a></tt> +<p>Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d +memory is automatically released when the function returns. The '<tt>alloca</tt>' +instruction is commonly used to represent automatic variables that must +have an address available. When the function returns (either with the <tt><a + href="#i_ret">ret</a></tt> or <tt><a href="#i_invoke">invoke</a></tt> instructions), the memory is reclaimed.</p> - <h5>Example:</h5> - -<pre> - %ptr = alloca int <i>; yields {int*}:ptr</i> +<pre> %ptr = alloca int <i>; yields {int*}:ptr</i> %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_load">'<tt>load</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = load <ty>* <pointer> - <result> = volatile load <ty>* <pointer> -</pre> - +<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 -to load from. The pointer must point to a <a href="t_firstclass">first -class</a> type. If the <tt>load</tt> is marked as <tt>volatile</tt> then the -optimizer is not allowed to modify the number or order of execution of this -<tt>load</tt> with other volatile <tt>load</tt> and <tt><a -href="#i_store">store</a></tt> instructions. </p> - +<p>The argument to the '<tt>load</tt>' instruction specifies the memory +address to load from. The pointer must point to a <a + href="t_firstclass">first class</a> type. If the <tt>load</tt> is +marked as <tt>volatile</tt> then the optimizer is not allowed to modify +the number or order of execution of this <tt>load</tt> with other +volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt> +instructions. </p> <h5>Semantics:</h5> - <p>The location of memory pointed to is loaded.</p> - <h5>Examples:</h5> - -<pre> - %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i> - <a href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i> +<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i> + <a + href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i> %val = load int* %ptr <i>; yields {int}:val = int 3</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_store">'<tt>store</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>' +Instruction</a> </div> <h5>Syntax:</h5> - -<pre> - store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i> +<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 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. -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> - +<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. 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> int <i>; yields {int*}:ptr</i> - <a href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i> +<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i> + <a + href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i> %val = load int* %ptr <i>; yields {int}:val = int 3</i> </pre> - -</div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a> -</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>{, long <aidx>|, ubyte <sidx>}* -</pre> - +<pre> <result> = getelementptr <ty>* <ptrval>{, long <aidx>|, ubyte <sidx>}*<br></pre> <h5>Overview:</h5> - -<p>The '<tt>getelementptr</tt>' instruction is used to get the address of a -subelement of an aggregate data structure.</p> - +<p>The '<tt>getelementptr</tt>' instruction is used to get the address +of a subelement of an aggregate data structure.</p> <h5>Arguments:</h5> - <p>This instruction takes a list of <tt>long</tt> values and <tt>ubyte</tt> -constants that indicate what form of addressing to perform. The actual types of -the arguments provided depend on the type of the first pointer argument. The -'<tt>getelementptr</tt>' instruction is used to index down through the type -levels of a structure.</p> - -<p>For example, let's consider a C code fragment and how it gets compiled to -LLVM:</p> - -<pre> -struct RT { - char A; - int B[10][20]; - char C; -}; -struct ST { - int X; - double Y; - struct RT Z; -}; - -int *foo(struct ST *s) { - return &s[1].Z.B[5][13]; -} -</pre> - +constants that indicate what form of addressing to perform. The actual +types of the arguments provided depend on the type of the first pointer +argument. The '<tt>getelementptr</tt>' instruction is used to index +down through the type levels of a structure.</p> +<p>For example, let's consider a C code fragment and how it gets +compiled to LLVM:</p> +<pre>struct RT {<br> char A;<br> int B[10][20];<br> char C;<br>};<br>struct ST {<br> int X;<br> double Y;<br> struct RT Z;<br>};<br><br>int *foo(struct ST *s) {<br> return &s[1].Z.B[5][13];<br>}<br></pre> <p>The LLVM code generated by the GCC frontend is:</p> - -<pre> -%RT = type { sbyte, [10 x [20 x int]], sbyte } -%ST = type { int, double, %RT } - -int* "foo"(%ST* %s) { - %reg = getelementptr %ST* %s, long 1, ubyte 2, ubyte 1, long 5, long 13 - ret int* %reg -} -</pre> - +<pre>%RT = type { sbyte, [10 x [20 x int]], sbyte }<br>%ST = type { int, double, %RT }<br><br>int* "foo"(%ST* %s) {<br> %reg = getelementptr %ST* %s, long 1, ubyte 2, ubyte 1, long 5, long 13<br> ret int* %reg<br>}<br></pre> <h5>Semantics:</h5> - -<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend -on the pointer type that is being index into. <a href="t_pointer">Pointer</a> -and <a href="t_array">array</a> types require '<tt>long</tt>' values, and <a -href="t_struct">structure</a> types require '<tt>ubyte</tt>' -<b>constants</b>.</p> - +<p>The index types specified for the '<tt>getelementptr</tt>' +instruction depend on the pointer type that is being index into. <a + href="t_pointer">Pointer</a> and <a href="t_array">array</a> types +require '<tt>long</tt>' values, and <a href="t_struct">structure</a> +types require '<tt>ubyte</tt>' <b>constants</b>.</p> <p>In the example above, the first index is indexing into the '<tt>%ST*</tt>' -type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT -}</tt>' type, a structure. The second index indexes into the third element of -the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]], -sbyte }</tt>' type, another structure. The third index indexes into the second -element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an -array. The two dimensions of the array are subscripted into, yielding an -'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction return a pointer -to this element, thus yielding a '<tt>int*</tt>' type.</p> - -<p>Note that it is perfectly legal to index partially through a structure, -returning a pointer to an inner element. Because of this, the LLVM code for the -given testcase is equivalent to:</p> - -<pre> -int* "foo"(%ST* %s) { - %t1 = getelementptr %ST* %s , long 1 <i>; yields %ST*:%t1</i> +type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, +double, %RT }</tt>' type, a structure. The second index indexes into +the third element of the structure, yielding a '<tt>%RT</tt>' = '<tt>{ +sbyte, [10 x [20 x int]], sbyte }</tt>' type, another structure. The +third index indexes into the second element of the structure, yielding +a '<tt>[10 x [20 x int]]</tt>' type, an array. The two dimensions of +the array are subscripted into, yielding an '<tt>int</tt>' type. The '<tt>getelementptr</tt>' +instruction return a pointer to this element, thus yielding a '<tt>int*</tt>' +type.</p> +<p>Note that it is perfectly legal to index partially through a +structure, returning a pointer to an inner element. Because of this, +the LLVM code for the given testcase is equivalent to:</p> +<pre>int* "foo"(%ST* %s) {<br> %t1 = getelementptr %ST* %s , long 1 <i>; yields %ST*:%t1</i> %t2 = getelementptr %ST* %t1, long 0, ubyte 2 <i>; yields %RT*:%t2</i> %t3 = getelementptr %RT* %t2, long 0, ubyte 1 <i>; yields [10 x [20 x int]]*:%t3</i> %t4 = getelementptr [10 x [20 x int]]* %t3, long 0, long 5 <i>; yields [20 x int]*:%t4</i> @@ -1866,450 +1408,281 @@ int* "foo"(%ST* %s) { ret int* %t5 } </pre> - <h5>Example:</h5> - -<pre> - <i>; yields [12 x ubyte]*:aptr</i> - %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, ubyte 1 -</pre> - -</div> - +<pre> <i>; yields [12 x ubyte]*:aptr</i> + %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, ubyte 1<br></pre> +<h5> Note To The Novice:</h5> +When using indexing into global arrays with the '<tt>getelementptr</tt>' +instruction, you must remember that the </div> <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="otherops">Other Operations</a> -</div> - +<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div> <div class="doc_text"> - -<p>The instructions in this catagory are the "miscellaneous" instructions, which -defy better classification.</p> - +<p>The instructions in this catagory are the "miscellaneous" +instructions, which defy better classification.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_phi">'<tt>phi</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = phi <ty> [ <val0>, <label0>], ... -</pre> - +<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> - +<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> - +<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> - +<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... - %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ] - %nextindvar = add uint %indvar, 1 - br label %Loop -</pre> - +<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_cast">'<tt>cast .. to</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = cast <ty> <value> to <ty2> <i>; yields ty2</i> +<pre> <result> = cast <ty> <value> to <ty2> <i>; yields ty2</i> </pre> - <h5>Overview:</h5> - -<p>The '<tt>cast</tt>' instruction is used as the primitive means to convert -integers to floating point, change data type sizes, and break type safety (by -casting pointers).</p> - +<p>The '<tt>cast</tt>' instruction is used as the primitive means to +convert integers to floating point, change data type sizes, and break +type safety (by casting pointers).</p> <h5>Arguments:</h5> - -<p>The '<tt>cast</tt>' instruction takes a value to cast, which must be a first -class value, and a type to cast it to, which must also be a <a -href="#t_firstclass">first class</a> type.</p> - +<p>The '<tt>cast</tt>' instruction takes a value to cast, which must be +a first class value, and a type to cast it to, which must also be a <a + href="#t_firstclass">first class</a> type.</p> <h5>Semantics:</h5> - -<p>This instruction follows the C rules for explicit casts when determining how -the data being cast must change to fit in its new container.</p> - -<p>When casting to bool, any value that would be considered true in the context -of a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' +<p>This instruction follows the C rules for explicit casts when +determining how the data being cast must change to fit in its new +container.</p> +<p>When casting to bool, any value that would be considered true in the +context of a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values, all else are '<tt>false</tt>'.</p> - -<p>When extending an integral value from a type of one signness to another (for -example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the -<b>source</b> value is signed, and zero-extended if the source value is -unsigned. <tt>bool</tt> values are always zero extended into either zero or -one.</p> - +<p>When extending an integral value from a type of one signness to +another (for example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value +is sign-extended if the <b>source</b> value is signed, and +zero-extended if the source value is unsigned. <tt>bool</tt> values +are always zero extended into either zero or one.</p> <h5>Example:</h5> - -<pre> - %X = cast int 257 to ubyte <i>; yields ubyte:1</i> +<pre> %X = cast int 257 to ubyte <i>; yields ubyte:1</i> %Y = cast int 123 to bool <i>; yields bool:true</i> </pre> - </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_call">'<tt>call</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <result> = call <ty>* <fnptrval>(<param list>) -</pre> - +<pre> <result> = call <ty>* <fnptrval>(<param list>)<br></pre> <h5>Overview:</h5> - <p>The '<tt>call</tt>' instruction represents a simple function call.</p> - <h5>Arguments:</h5> - <p>This instruction requires several arguments:</p> - <ol> - - <li><p>'<tt>ty</tt>': shall be the signature of the pointer to function value - being invoked. The argument types must match the types implied by this - signature.</p></li> - - <li><p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function - to be invoked. In most cases, this is a direct function invocation, but - indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer to - function values.</p></li> - - <li><p>'<tt>function args</tt>': argument list whose types match the function - signature argument types. If the function signature indicates the function - accepts a variable number of arguments, the extra arguments can be - specified.</p></li> - + <li> + <p>'<tt>ty</tt>': shall be the signature of the pointer to function +value being invoked. The argument types must match the types implied +by this signature.</p> + </li> + <li> + <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a +function to be invoked. In most cases, this is a direct function +invocation, but indirect <tt>call</tt>s are just as possible, +calling an arbitrary pointer to function values.</p> + </li> + <li> + <p>'<tt>function args</tt>': argument list whose types match the +function signature argument types. If the function signature +indicates the function accepts a variable number of arguments, the +extra arguments can be specified.</p> + </li> </ol> - <h5>Semantics:</h5> - -<p>The '<tt>call</tt>' instruction is used to cause control flow to transfer to -a specified function, with its incoming arguments bound to the specified values. -Upon a '<tt><a href="#i_ret">ret</a></tt>' instruction in the called function, -control flow continues with the instruction after the function call, and the -return value of the function is bound to the result argument. This is a simpler -case of the <a href="#i_invoke">invoke</a> instruction.</p> - +<p>The '<tt>call</tt>' instruction is used to cause control flow to +transfer to a specified function, with its incoming arguments bound to +the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>' +instruction in the called function, control flow continues with the +instruction after the function call, and the return value of the +function is bound to the result argument. This is a simpler case of +the <a href="#i_invoke">invoke</a> instruction.</p> <h5>Example:</h5> - -<pre> - %retval = call int %test(int %argc) - call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42); -</pre> - +<pre> %retval = call int %test(int %argc)<br> call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<br></pre> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_vanext">'<tt>vanext</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_vanext">'<tt>vanext</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <resultarglist> = vanext <va_list> <arglist>, <argty> -</pre> - +<pre> <resultarglist> = vanext <va_list> <arglist>, <argty><br></pre> <h5>Overview:</h5> - -<p>The '<tt>vanext</tt>' instruction is used to access arguments passed through -the "variable argument" area of a function call. It is used to implement the -<tt>va_arg</tt> macro in C.</p> - +<p>The '<tt>vanext</tt>' instruction is used to access arguments passed +through the "variable argument" area of a function call. It is used to +implement the <tt>va_arg</tt> macro in C.</p> <h5>Arguments:</h5> - -<p>This instruction takes a <tt>valist</tt> value and the type of the argument. -It returns another <tt>valist</tt>.</p> - +<p>This instruction takes a <tt>valist</tt> value and the type of the +argument. It returns another <tt>valist</tt>.</p> <h5>Semantics:</h5> - -<p>The '<tt>vanext</tt>' instruction advances the specified <tt>valist</tt> past -an argument of the specified type. In conjunction with the <a -href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement the -<tt>va_arg</tt> macro available in C. For more information, see the variable -argument handling <a href="#int_varargs">Intrinsic Functions</a>.</p> - -<p>It is legal for this instruction to be called in a function which does not -take a variable number of arguments, for example, the <tt>vfprintf</tt> +<p>The '<tt>vanext</tt>' instruction advances the specified <tt>valist</tt> +past an argument of the specified type. In conjunction with the <a + href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement +the <tt>va_arg</tt> macro available in C. For more information, see +the variable argument handling <a href="#int_varargs">Intrinsic +Functions</a>.</p> +<p>It is legal for this instruction to be called in a function which +does not take a variable number of arguments, for example, the <tt>vfprintf</tt> function.</p> - <p><tt>vanext</tt> is an LLVM instruction instead of an <a -href="#intrinsics">intrinsic function</a> because it takes an type as an -argument.</p> - + href="#intrinsics">intrinsic function</a> because it takes an type as +an argument.</p> <h5>Example:</h5> - -<p>See the <a href="#int_varargs">variable argument processing</a> section.</p> - +<p>See the <a href="#int_varargs">variable argument processing</a> +section.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a> -</div> - +<div class="doc_subsubsection"> <a name="i_vaarg">'<tt>vaarg</tt>' +Instruction</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - <resultval> = vaarg <va_list> <arglist>, <argty> -</pre> - +<pre> <resultval> = vaarg <va_list> <arglist>, <argty><br></pre> <h5>Overview:</h5> - -<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed through -the "variable argument" area of a function call. It is used to implement the -<tt>va_arg</tt> macro in C.</p> - +<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed +through the "variable argument" area of a function call. It is used to +implement the <tt>va_arg</tt> macro in C.</p> <h5>Arguments:</h5> - -<p>This instruction takes a <tt>valist</tt> value and the type of the argument. -It returns a value of the specified argument type.</p> - +<p>This instruction takes a <tt>valist</tt> value and the type of the +argument. It returns a value of the specified argument type.</p> <h5>Semantics:</h5> - -<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified type from -the specified <tt>va_list</tt>. In conjunction with the <a -href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to implement the -<tt>va_arg</tt> macro available in C. For more information, see the variable -argument handling <a href="#int_varargs">Intrinsic Functions</a>.</p> - -<p>It is legal for this instruction to be called in a function which does not -take a variable number of arguments, for example, the <tt>vfprintf</tt> +<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified +type from the specified <tt>va_list</tt>. In conjunction with the <a + href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to +implement the <tt>va_arg</tt> macro available in C. For more +information, see the variable argument handling <a href="#int_varargs">Intrinsic +Functions</a>.</p> +<p>It is legal for this instruction to be called in a function which +does not take a variable number of arguments, for example, the <tt>vfprintf</tt> function.</p> - <p><tt>vaarg</tt> is an LLVM instruction instead of an <a -href="#intrinsics">intrinsic function</a> because it takes an type as an -argument.</p> - + href="#intrinsics">intrinsic function</a> because it takes an type as +an argument.</p> <h5>Example:</h5> - -<p>See the <a href="#int_varargs">variable argument processing</a> section.</p> - +<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_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>Unless an intrinsic function is target-specific, there must be a lowering -pass to eliminate the intrinsic or all backends must support the intrinsic -function.</p> - +<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>Unless an intrinsic function is target-specific, there must be a +lowering pass to eliminate the intrinsic or all backends must support +the intrinsic function.</p> </div> - <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="int_varargs">Variable Argument Handling Intrinsics</a> -</div> - +<div class="doc_subsection"> <a name="int_varargs">Variable Argument +Handling Intrinsics</a> </div> <div class="doc_text"> - <p>Variable argument support is defined in LLVM with the <a -href="#i_vanext"><tt>vanext</tt></a> instruction and these three intrinsic -functions. These functions are related to the similarly named macros defined in -the <tt><stdarg.h></tt> header file.</p> - -<p>All of these functions operate on arguments that use a target-specific value -type "<tt>va_list</tt>". The LLVM assembly language reference manual does not -define what this type is, so all transformations should be prepared to handle -intrinsics with any type used.</p> - + href="#i_vanext"><tt>vanext</tt></a> instruction and these three +intrinsic functions. These functions are related to the similarly +named macros defined in the <tt><stdarg.h></tt> header file.</p> +<p>All of these functions operate on arguments that use a +target-specific value type "<tt>va_list</tt>". The LLVM assembly +language reference manual does not define what this type is, so all +transformations should be prepared to handle intrinsics with any type +used.</p> <p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a> -instruction and the variable argument handling intrinsic functions are used.</p> - -<pre> -int %test(int %X, ...) { - ; Initialize variable argument processing - %ap = call sbyte*()* %<a href="#i_va_start">llvm.va_start</a>() - - ; Read a single integer argument - %tmp = vaarg sbyte* %ap, int - - ; Advance to the next argument - %ap2 = vanext sbyte* %ap, int - - ; Demonstrate usage of llvm.va_copy and llvm.va_end - %aq = call sbyte* (sbyte*)* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2) - call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq) - - ; Stop processing of arguments. - call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2) - ret int %tmp -} -</pre> - +instruction and the variable argument handling intrinsic functions are +used.</p> +<pre>int %test(int %X, ...) {<br> ; Initialize variable argument processing<br> %ap = call sbyte*()* %<a + href="#i_va_start">llvm.va_start</a>()<br><br> ; Read a single integer argument<br> %tmp = vaarg sbyte* %ap, int<br><br> ; Advance to the next argument<br> %ap2 = vanext sbyte* %ap, int<br><br> ; Demonstrate usage of llvm.va_copy and llvm.va_end<br> %aq = call sbyte* (sbyte*)* %<a + href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)<br> call void %<a + href="#i_va_end">llvm.va_end</a>(sbyte* %aq)<br><br> ; Stop processing of arguments.<br> call void %<a + href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)<br> ret int %tmp<br>}<br></pre> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a> -</div> - +<div class="doc_subsubsection"> <a name="i_va_start">'<tt>llvm.va_start</tt>' +Intrinsic</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - call va_list ()* %llvm.va_start() -</pre> - +<pre> call va_list ()* %llvm.va_start()<br></pre> <h5>Overview:</h5> - <p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt><arglist></tt> for subsequent use by the variable argument intrinsics.</p> - <h5>Semantics:</h5> - <p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt> -macro available in C. In a target-dependent way, it initializes and returns a -<tt>va_list</tt> element, so that the next <tt>vaarg</tt> will produce the first -variable argument passed to the function. Unlike the C <tt>va_start</tt> macro, -this intrinsic does not need to know the last argument of the function, the -compiler can figure that out.</p> - -<p>Note that this intrinsic function is only legal to be called from within the -body of a variable argument function.</p> - +macro available in C. In a target-dependent way, it initializes and +returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt> +will produce the first variable argument passed to the function. Unlike +the C <tt>va_start</tt> macro, this intrinsic does not need to know the +last argument of the function, the compiler can figure that out.</p> +<p>Note that this intrinsic function is only legal to be called from +within the body of a variable argument function.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a> -</div> - +<div class="doc_subsubsection"> <a name="i_va_end">'<tt>llvm.va_end</tt>' +Intrinsic</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - call void (va_list)* %llvm.va_end(va_list <arglist>) -</pre> - +<pre> call void (va_list)* %llvm.va_end(va_list <arglist>)<br></pre> <h5>Overview:</h5> - -<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> - +<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> - <p>The argument is a <tt>va_list</tt> to destroy.</p> - <h5>Semantics:</h5> - <p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt> -macro available in C. In a target-dependent way, it destroys the -<tt>va_list</tt>. Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and -<a href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly with -calls to <tt>llvm.va_end</tt>.</p> - +macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>. +Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a + href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly +with calls to <tt>llvm.va_end</tt>.</p> </div> - <!-- _______________________________________________________________________ --> -<div class="doc_subsubsection"> - <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a> -</div> - +<div class="doc_subsubsection"> <a name="i_va_copy">'<tt>llvm.va_copy</tt>' +Intrinsic</a> </div> <div class="doc_text"> - <h5>Syntax:</h5> - -<pre> - call va_list (va_list)* %llvm.va_copy(va_list <destarglist>) -</pre> - +<pre> call va_list (va_list)* %llvm.va_copy(va_list <destarglist>)<br></pre> <h5>Overview:</h5> - -<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position -from the source argument list to the destination argument list.</p> - +<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument +position from the source argument list to the destination argument list.</p> <h5>Arguments:</h5> - <p>The argument is the <tt>va_list</tt> to copy.</p> - <h5>Semantics:</h5> - <p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> -macro available in C. In a target-dependent way, it copies the source -<tt>va_list</tt> element into the returned list. This intrinsic is necessary -because the <tt><a href="i_va_start">llvm.va_start</a></tt> intrinsic may be -arbitrarily complex and require memory allocation, for example.</p> - +macro available in C. In a target-dependent way, it copies the source <tt>va_list</tt> +element into the returned list. This intrinsic is necessary because the <tt><a + href="i_va_start">llvm.va_start</a></tt> intrinsic may be arbitrarily +complex and require memory allocation, for example.</p> </div> - <!-- *********************************************************************** --> - <hr> <div class="doc_footer"> - <address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address> - <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> - <br> - Last modified: $Date$ -</div> - +<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address> +<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> <br> +Last modified: $Date$ </div> </body> </html> |