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Document unreachable instruction

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llvm-svn: 17033
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Chris Lattner 2004-10-16 18:04:13 +00:00
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@ -51,6 +51,7 @@
<li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
<li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
<li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
<li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
</ol>
</li>
<li><a href="#binaryops">Binary Operations</a>
@ -753,8 +754,9 @@ the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
<p>There are five different terminator instructions: the '<a
href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, and the '<a
href="#i_unwind"><tt>unwind</tt></a>' instruction.</p>
the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
@ -920,26 +922,63 @@ support them.</p>
<pre> %retval = invoke int %Test(int 15)<br> to label %Continue<br> except label %TestCleanup <i>; {int}:retval set</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre> unwind<br></pre>
<pre>
unwind
</pre>
<h5>Overview:</h5>
<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing
control flow at the first callee in the dynamic call stack which used
an <a href="#i_invoke"><tt>invoke</tt></a> instruction to perform the
call. This is primarily used to implement exception handling.</p>
<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
at the first callee in the dynamic call stack which used an <a
href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
primarily used to implement exception handling.</p>
<h5>Semantics:</h5>
<p>The '<tt>unwind</tt>' intrinsic causes execution of the current
function to immediately halt. The dynamic call stack is then searched
for the first <a href="#i_invoke"><tt>invoke</tt></a> instruction on
the call stack. Once found, execution continues at the "exceptional"
destination block specified by the <tt>invoke</tt> instruction. If
there is no <tt>invoke</tt> instruction in the dynamic call chain,
undefined behavior results.</p>
<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
immediately halt. The dynamic call stack is then searched for the first <a
href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
execution continues at the "exceptional" destination block specified by the
<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
dynamic call chain, undefined behavior results.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
unreachable
</pre>
<h5>Overview:</h5>
<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
instruction is used to inform the optimizer that a particular portion of the
code is not reachable. This can be used to indicate that the code after a
no-return function cannot be reached, and other facts.</p>
<h5>Semantics:</h5>
<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
<div class="doc_text">