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<h3 class="section">11.12 Statement and operand traversals</h3>
<p><a name="index-Statement-and-operand-traversals-2501"></a>
There are two functions available for walking statements and
sequences: <code>walk_gimple_stmt</code> and <code>walk_gimple_seq</code>,
accordingly, and a third function for walking the operands in a
statement: <code>walk_gimple_op</code>.
<div class="defun">
— GIMPLE function: tree <b>walk_gimple_stmt</b> (<var>gimple_stmt_iterator *gsi, walk_stmt_fn callback_stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi</var>)<var><a name="index-walk_005fgimple_005fstmt-2502"></a></var><br>
<blockquote><p>This function is used to walk the current statement in <code>GSI</code>,
optionally using traversal state stored in <code>WI</code>. If <code>WI</code> is <code>NULL</code>, no
state is kept during the traversal.
<p>The callback <code>CALLBACK_STMT</code> is called. If <code>CALLBACK_STMT</code> returns
true, it means that the callback function has handled all the
operands of the statement and it is not necessary to walk its
operands.
<p>If <code>CALLBACK_STMT</code> is <code>NULL</code> or it returns false, <code>CALLBACK_OP</code> is
called on each operand of the statement via <code>walk_gimple_op</code>. If
<code>walk_gimple_op</code> returns non-<code>NULL</code> for any operand, the remaining
operands are not scanned.
<p>The return value is that returned by the last call to
<code>walk_gimple_op</code>, or <code>NULL_TREE</code> if no <code>CALLBACK_OP</code> is specified.
</p></blockquote></div>
<div class="defun">
— GIMPLE function: tree <b>walk_gimple_op</b> (<var>gimple stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi</var>)<var><a name="index-walk_005fgimple_005fop-2503"></a></var><br>
<blockquote><p>Use this function to walk the operands of statement <code>STMT</code>. Every
operand is walked via <code>walk_tree</code> with optional state information
in <code>WI</code>.
<p><code>CALLBACK_OP</code> is called on each operand of <code>STMT</code> via <code>walk_tree</code>.
Additional parameters to <code>walk_tree</code> must be stored in <code>WI</code>. For
each operand <code>OP</code>, <code>walk_tree</code> is called as:
<pre class="smallexample"> walk_tree (&<code>OP</code>, <code>CALLBACK_OP</code>, <code>WI</code>, <code>PSET</code>)
</pre>
<p>If <code>CALLBACK_OP</code> returns non-<code>NULL</code> for an operand, the remaining
operands are not scanned. The return value is that returned by
the last call to <code>walk_tree</code>, or <code>NULL_TREE</code> if no <code>CALLBACK_OP</code> is
specified.
</p></blockquote></div>
<div class="defun">
— GIMPLE function: tree <b>walk_gimple_seq</b> (<var>gimple_seq seq, walk_stmt_fn callback_stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi</var>)<var><a name="index-walk_005fgimple_005fseq-2504"></a></var><br>
<blockquote><p>This function walks all the statements in the sequence <code>SEQ</code>
calling <code>walk_gimple_stmt</code> on each one. <code>WI</code> is as in
<code>walk_gimple_stmt</code>. If <code>walk_gimple_stmt</code> returns non-<code>NULL</code>, the walk
is stopped and the value returned. Otherwise, all the statements
are walked and <code>NULL_TREE</code> returned.
</p></blockquote></div>
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