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Document 'inreg' & 'sret'

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33600 91177308-0d34-0410-b5e6-96231b3b80d8
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Anton Korobeynikov 2007-01-28 14:30:45 +00:00
parent 9adeaa2f59
commit 34d6dea849
1 changed files with 7 additions and 19 deletions
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@ -530,19 +530,6 @@ the future:</p>
prototype and implemented declaration of the function (as does normal C).
</dd>
<dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
<dd>This calling convention matches the target C calling conventions, except
that functions with this convention are required to take a pointer as their
first argument, and the return type of the function must be void. This is
used for C functions that return aggregates by-value. In this case, the
function has been transformed to take a pointer to the struct as the first
argument to the function. For targets where the ABI specifies specific
behavior for structure-return calls, the calling convention can be used to
distinguish between struct return functions and other functions that take a
pointer to a struct as the first argument.
</dd>
<dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
<dd>This calling convention attempts to make calls as fast as possible
@ -743,14 +730,15 @@ a power of 2.</p>
<dt><tt>sext</tt></dt>
<dd>This indicates that the parameter should be sign extended just before
a call to this function.</dd>
<dt><tt>inreg</tt></dt>
<dd>This indicates that the parameter should be placed in register (if
possible) during assembling function call. It's currently supported in x86
backend only.</dd>
<dt><tt>sret</tt></dt>
<dd>This indicates, that the parameter is special hidden pointer to struct
to return. Usually such parameter needs special handling during codegen.</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
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>
</div>
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