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Update documentation for parameter attributes for the syntax change.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33238 91177308-0d34-0410-b5e6-96231b3b80d8
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Reid Spencer 2007-01-15 18:27:39 +00:00
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docs/LangRef.html
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@ -687,27 +687,29 @@ a power of 2.</p>
type so two functions types that differ only by the parameter attributes
are different function types.</p>
<p>Parameter attributes consist of an at sign (@) followed by either a single
keyword or a comma separate list of keywords enclosed in parentheses. For
<p>Parameter attributes are simple keywords that follow the type specified. If
multiple parameter attributes are needed, they are space separated. For
example:</p><pre>
%someFunc = i16 @zext (i8 @(sext) %someParam)
%someFunc = i16 @zext (i8 @zext %someParam)</pre>
%someFunc = i16 (i8 sext %someParam) zext
%someFunc = i16 (i8 zext %someParam) zext</pre>
<p>Note that the two function types above are unique because the parameter has
a different attribute (@sext in the first one, @zext in the second).</p>
a different attribute (sext in the first one, zext in the second). Also note
that the attribute for the function result (zext) comes immediately after the
argument list.</p>
<p>Currently, only the following parameter attributes are defined:</p>
<dl>
<dt><tt>@zext</tt></dt>
<dt><tt>zext</tt></dt>
<dd>This indicates that the parameter should be zero extended just before
a call to this function.</dd>
<dt><tt>@sext</tt></dt>
<dt><tt>sext</tt></dt>
<dd>This indicates that the parameter should be sign extended just before
a call to this function.</dd>
</dl>
<p>The current motivation for parameter attributes is to enable the sign and
zero extend information necessary for the C calling convention to be passed
from the front end to LLVM. The <tt>@zext</tt> and <tt>@sext</tt> attributes
from the front end to LLVM. The <tt>zext</tt> and <tt>sext</tt> attributes
are used by the code generator to perform the required extension. However,
parameter attributes are an orthogonal feature to calling conventions and
may be used for other purposes in the future.</p>