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move "Metadata Nodes and Metadata Strings" section to the right place in the

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document and edit it.

llvm-svn: 93559
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Chris Lattner 2010-01-15 21:50:19 +00:00
parent 3c5d9dc0e3
commit c94ab2c354
1 changed files with 32 additions and 38 deletions
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docs/LangRef.html
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@ -924,9 +924,9 @@ define [<a href="#linkage">linkage</a>] [<a href="#visibility">visibility</a>]
<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 @@ has undefined behavior.</p>
</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 @@ call void asm alignstack "eieio", ""()
</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">