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author | Chris Lattner <sabre@nondot.org> | 2007-05-12 03:23:40 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2007-05-12 03:23:40 +0000 |
commit | e9ef4573e28dfae9949da574b135e72652f79b24 (patch) | |
tree | 650ebc122ac659fa771965e905a8e149511de5b4 /docs/BitCodeFormat.html | |
parent | be1b1b1a74b3c70e76c70671b7c0affa150884fa (diff) | |
download | external_llvm-e9ef4573e28dfae9949da574b135e72652f79b24.zip external_llvm-e9ef4573e28dfae9949da574b135e72652f79b24.tar.gz external_llvm-e9ef4573e28dfae9949da574b135e72652f79b24.tar.bz2 |
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diff --git a/docs/BitCodeFormat.html b/docs/BitCodeFormat.html index 0579a42..949de94 100644 --- a/docs/BitCodeFormat.html +++ b/docs/BitCodeFormat.html @@ -4,56 +4,126 @@ <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>LLVM Bitcode File Format</title> <link rel="stylesheet" href="llvm.css" type="text/css"> - <style type="text/css"> - TR, TD { border: 2px solid gray; padding-left: 4pt; padding-right: 4pt; - padding-top: 2pt; padding-bottom: 2pt; } - TH { border: 2px solid gray; font-weight: bold; font-size: 105%; } - TABLE { text-align: center; border: 2px solid black; - border-collapse: collapse; margin-top: 1em; margin-left: 1em; - margin-right: 1em; margin-bottom: 1em; } - .td_left { border: 2px solid gray; text-align: left; } - </style> </head> <body> <div class="doc_title"> LLVM Bitcode File Format </div> <ol> <li><a href="#abstract">Abstract</a></li> - <li><a href="#concepts">Concepts</a></li> + <li><a href="#overview">Overview</a></li> + <li><a href="#bitstream">Bitstream Format</a> + <ol> + <li><a href="#magic">Magic Numbers</a></li> + </ol> + </li> + <li><a href="#llvmir">LLVM IR Encoding</a></li> </ol> <div class="doc_author"> - <p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a> and - <a href="mailto:sabre@nondot.org">Chris Lattner</a>. + <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>. </p> </div> + <!-- *********************************************************************** --> -<div class="doc_section"> <a name="abstract">Abstract </a></div> +<div class="doc_section"> <a name="abstract">Abstract</a></div> <!-- *********************************************************************** --> + <div class="doc_text"> -<p>This document describes the LLVM bitcode file format. It specifies -the binary encoding rules of the bitcode file format so that -equivalent systems can encode bitcode files correctly. The LLVM -bitcode representation is used to store the intermediate -representation on disk in a compacted form.</p> -<p>This document supercedes the LLVM bytecode file format for the 2.0 -release.</p> + +<p>This document describes the LLVM bitstream file format and the encoding of +the LLVM IR into it.</p> + </div> + <!-- *********************************************************************** --> -<div class="doc_section"> <a name="concepts">Concepts</a> </div> +<div class="doc_section"> <a name="overview">Overview</a></div> <!-- *********************************************************************** --> + <div class="doc_text"> -<p>This section describes the general concepts of the bitcode file -format without getting into specific layout details. It is recommended -that you read this section thoroughly before interpreting the detailed -descriptions.</p> + +<p> +What is commonly known as the LLVM bitcode file format (also, sometimes +anachronistically known as bytecode) is actually two things: a <a +href="#bitstream">bitstream container format</a> +and an <a href="#llvmir">encoding of LLVM IR</a> into the container format.</p> + +<p> +The bitstream format is an abstract encoding of structured data, like very +similar to XML in some ways. Like XML, bitstream files contain tags, and nested +structures, and you can parse the file without having to understand the tags. +Unlike XML, the bitstream format is a binary encoding, and unlike XML it +provides a mechanism for the file to self-describe "abbreviations", which are +effectively size optimizations for the content.</p> + +<p>This document first describes the LLVM bitstream format, then describes the +record structure used by LLVM IR files. +</p> + +</div> + +<!-- *********************************************************************** --> +<div class="doc_section"> <a name="bitstream">Bitstream Format</a></div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p> +The bitstream format is literally a stream of bits, with a very simple +structure. This structure consists of the following concepts: +</p> + +<ul> +<li>A magic number that identifies the stream.</li> +<li>Encoding primitives like variable bit-rate integers.</li> +<li>Blocks, which define nested content.</li> +<li>Data Records, which describe entities within the file.</li> +<li>Abbreviations, which specify compression optimizations for the file.</li> +</ul> + +<p>Note that the <a +href="CommandGuide/html/llvm-bcanalyzer.html">llvm-bcanalyzer</a> tool can be +used to dump and inspect arbitrary bitstreams, which is very useful for +understanding the encoding.</p> + +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"><a name="magic">Magic Numbers</a> +</div> + +<div class="doc_text"> + +<p>LLVM </p> + +</div> + + +<!-- _______________________________________________________________________ --> +<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div> + +<div class="doc_text"> + +<p>blah +</p> + +</div> + +<!-- *********************************************************************** --> +<div class="doc_section"> <a name="llvmir">LLVM IR Encoding</a></div> +<!-- *********************************************************************** --> + +<div class="doc_text"> + +<p></p> + </div> + + <!-- *********************************************************************** --> <hr> <address> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a> <a href="http://validator.w3.org/check/referer"><img src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a> -<a href="mailto:rspencer@x10sys.com">Reid Spencer</a> and <a - href="mailto:sabre@nondot.org">Chris Lattner</a><br> + <a href="mailto:sabre@nondot.org">Chris Lattner</a><br> <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br> Last modified: $Date$ </address> |