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Add info on new 'tail' marker

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21721 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2005-05-06 05:47:36 +00:00
parent 19bdc03adc
commit 2bff524501
1 changed files with 37 additions and 11 deletions
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@ -2041,26 +2041,43 @@ value argument, otherwise it returns the second value argument.
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>'
Instruction</a> </div>
<div class="doc_subsubsection">
<a name="i_call">'<tt>call</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre> &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)<br></pre>
<pre>
&lt;result&gt; = [tail] call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
</pre>
<h5>Overview:</h5>
<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
<h5>Arguments:</h5>
<p>This instruction requires several arguments:</p>
<ol>
<li>
<p>'<tt>ty</tt>': shall be the signature of the pointer to function
value being invoked. The argument types must match the types implied
by this signature.</p>
<p>The "tail" marker indicates whether the callee function accesses any
allocas or varargs in the caller. If the "tail" marker is present, the
function call is eligible for tail call optimization. Note that calls may
be marked "tail" even if they do not occur before a <a
href="#i_ret"><tt>ret</tt></a> instruction.
</li>
<li>
<p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a
function to be invoked. In most cases, this is a direct function
invocation, but indirect <tt>call</tt>s are just as possible,
calling an arbitrary pointer to function values.</p>
<p>'<tt>ty</tt>': shall be the signature of the pointer to function value
being invoked. The argument types must match the types implied by this
signature.</p>
</li>
<li>
<p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
be invoked. In most cases, this is a direct function invocation, but
indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
to function values.</p>
</li>
<li>
<p>'<tt>function args</tt>': argument list whose types match the
@ -2070,7 +2087,9 @@ calling an arbitrary pointer to function values.</p>
arguments can be specified.</p>
</li>
</ol>
<h5>Semantics:</h5>
<p>The '<tt>call</tt>' instruction is used to cause control flow to
transfer to a specified function, with its incoming arguments bound to
the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
@ -2078,8 +2097,15 @@ instruction in the called function, control flow continues with the
instruction after the function call, and the return value of the
function is bound to the result argument. This is a simpler case of
the <a href="#i_invoke">invoke</a> instruction.</p>
<h5>Example:</h5>
<pre> %retval = call int %test(int %argc)<br> call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<br></pre>
<pre>
%retval = call int %test(int %argc)
call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
%X = tail call int %foo()
</pre>
</div>
<!-- _______________________________________________________________________ -->