[llvm-commits] [llvm] r93559 - /llvm/trunk/docs/LangRef.html

[Chris Lattner]

Author: lattner
Date: Fri Jan 15 15:50:19 2010
New Revision: 93559

URL: http://llvm.org/viewvc/llvm-project?rev=93559&view=rev
Log:
move "Metadata Nodes and Metadata Strings" section to the right place in the
document and edit it.


Modified:
    llvm/trunk/docs/LangRef.html

Modified: llvm/trunk/docs/LangRef.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.html?rev=93559&r1=93558&r2=93559&view=diff

==============================================================================
--- llvm/trunk/docs/LangRef.html (original)
+++ llvm/trunk/docs/LangRef.html Fri Jan 15 15:50:19 2010
@@ -924,9 +924,9 @@
 
 <div class="doc_text">
 
-<p>Named metadata is a collection of metadata. <a href="#metadata"> Metadata </a>
-   node and null are the only valid named metadata operands. 
-   Metadata strings are not allowed as an named metadata operand.</p>
+<p>Named metadata is a collection of metadata. <a href="#metadata">Metadata
+   nodes</a> (but not metadata strings) and null are the only valid operands for
+   a named metadata.</p>
 
 <h5>Syntax:</h5>
 <div class="doc_code">
@@ -2335,41 +2335,6 @@
 
 </div>
 
-<!-- ======================================================================= -->
-<div class="doc_subsection"><a name="metadata">Metadata Nodes and Metadata Strings</a>
-</div>
-
-<div class="doc_text">
-
-<p>Metadata provides a way to attach arbitrary data to the instruction
-   stream without affecting the behaviour of the program.  There are two
-   metadata primitives, strings and nodes. All metadata has the
-   <tt>metadata</tt> type and is identified in syntax by a preceding exclamation
-   point ('<tt>!</tt>').</p>
-
-<p>A metadata string is a string surrounded by double quotes.  It can contain
-   any character by escaping non-printable characters with "\xx" where "xx" is
-   the two digit hex code.  For example: "<tt>!"test\00"</tt>".</p>
-
-<p>Metadata nodes are represented with notation similar to structure constants
-   (a comma separated list of elements, surrounded by braces and preceded by an
-   exclamation point).  For example: "<tt>!{ metadata !"test\00", i32
-   10}</tt>".</p>
-
-<p>A metadata node will attempt to track changes to the values it holds. In the
-   event that a value is deleted, it will be replaced with a typeless
-   "<tt>null</tt>", such as "<tt>metadata !{null, i32 10}</tt>".</p>
-
-<p>A <a href="#namedmetadatastructure">named metadata</a> is a collection of 
-   metadata nodes. For example: "<tt>!foo =  metadata !{!4, !3}</tt>".
-
-<p>Optimizations may rely on metadata to provide additional information about
-   the program that isn't available in the instructions, or that isn't easily
-   computable. Similarly, the code generator may expect a certain metadata
-   format to be used to express debugging information.</p>
-
-</div>
-
 <!-- *********************************************************************** -->
 <div class="doc_section"> <a name="othervalues">Other Values</a> </div>
 <!-- *********************************************************************** -->
@@ -2439,6 +2404,35 @@
 
 </div>
 
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="metadata">Metadata Nodes and Metadata
+  Strings</a>
+</div>
+
+<div class="doc_text">
+
+<p>LLVM IR allows metadata to be attached to instructions in the program that
+   can convey extra information about the code to the optimizers and code
+   generator.  One example application of metadata is source-level debug
+   information.  There are two metadata primitives: strings and nodes. All
+   metadata has the <tt>metadata</tt> type and is identified in syntax by a
+   preceding exclamation point ('<tt>!</tt>').</p>
+
+<p>A metadata string is a string surrounded by double quotes.  It can contain
+   any character by escaping non-printable characters with "\xx" where "xx" is
+   the two digit hex code.  For example: "<tt>!"test\00"</tt>".</p>
+
+<p>Metadata nodes are represented with notation similar to structure constants
+   (a comma separated list of elements, surrounded by braces and preceded by an
+   exclamation point).  For example: "<tt>!{ metadata !"test\00", i32
+   10}</tt>".  Metadata nodes can have any values as their operand.</p>
+
+<p>A <a href="#namedmetadatastructure">named metadata</a> is a collection of 
+   metadata nodes, which can be looked up in the module symbol table. For
+   example: "<tt>!foo =  metadata !{!4, !3}</tt>".
+
+</div>
+
 
 <!-- *********************************************************************** -->
 <div class="doc_section">