[llvm-commits] CVS: llvm/docs/BitCodeFormat.html
Chris Lattner
sabre at nondot.org
Fri May 11 20:23:58 PDT 2007
Changes in directory llvm/docs:
BitCodeFormat.html updated: 1.1 -> 1.2
---
Log message:
first step
---
Diffs of the changes: (+98 -28)
BitCodeFormat.html | 126 +++++++++++++++++++++++++++++++++++++++++------------
1 files changed, 98 insertions(+), 28 deletions(-)
Index: llvm/docs/BitCodeFormat.html
diff -u llvm/docs/BitCodeFormat.html:1.1 llvm/docs/BitCodeFormat.html:1.2
--- llvm/docs/BitCodeFormat.html:1.1 Sat Jan 20 17:21:08 2007
+++ llvm/docs/BitCodeFormat.html Fri May 11 22:23:40 2007
@@ -4,58 +4,128 @@
<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 at x10sys.com">Reid Spencer</a> and
- <a href="mailto:sabre at nondot.org">Chris Lattner</a>.
+ <p>Written by <a href="mailto:sabre at 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 at x10sys.com">Reid Spencer</a> and <a
- href="mailto:sabre at nondot.org">Chris Lattner</a><br>
+ <a href="mailto:sabre at nondot.org">Chris Lattner</a><br>
<a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
-Last modified: $Date: 2007/01/20 23:21:08 $
+Last modified: $Date: 2007/05/12 03:23:40 $
</address>
</body>
</html>
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