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<title>Changes to PHP Internals</title>
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</div><hr /><div id="migration55.internals" class="sect1">
<h2 class="title">Changes to PHP Internals</h2>
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
Extensions cannot override <strong class="command">zend_execute()</strong> any more and
should override <strong class="command">zend_execute_ex()</strong> instead.
<em>EG(current_execute_data)</em> is already initialized in
<strong class="command">zend_execute_ex()</strong>, so for compatibility extensions may
need to use
<em>EG(current_execute_data)->prev_execute_data</em> instead.
</span>
</li>
<li class="listitem">
<span class="simpara">
Removed <em>EG(arg_types_stack)</em>,
<em>EX(fbc)</em>, <em>EX(called_scope)</em> and
<em>EX(current_object)</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Added <em>op_array->nested_calls</em>, which is calculated
at compile time.
</span>
</li>
<li class="listitem">
<span class="simpara">
Added <em>EX(call_slots)</em>, which is an array to store
information about syntaticaly nested calls (e.g.
<em>foo(bar())</em>) and is preallocated together with
<em>execute_data</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Added <em>EX(call)</em>, which is a pointer to a current
calling function, and is an element of <em>EX(call_slots)</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Opcodes
<a href="internals2.opcodes.init-method-call.html" class="link">INIT_METHOD_CALL</a>,
<a href="internals2.opcodes.init-static-method-call.html" class="link">ZEND_INIT_STATIC_METHOD_CALL</a>,
<a href="internals2.opcodes.init-fcall-by-name.html" class="link">ZEND_INIT_FCALL_BY_NAME</a>
and
<a href="internals2.opcodes.init-ns-fcall-by-name.html" class="link">ZEND_INIT_NS_FCALL_BY_NAME</a>
use <em>result.num</em> as an index in
<em>EX(call_slots)</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Opcode <a href="internals2.opcodes.new.html" class="link">ZEND_NEW</a> uses
<em>extended_value</em> as an index in
<em>EX(call_slots)</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Opcodes <a href="internals2.opcodes.do-fcall.html" class="link">ZEND_DO_FCALL</a>
and
<a href="internals2.opcodes.do-fcall-by-name.html" class="link">ZEND_DO_FCALL_BY_NAME</a>
use <em>op2.num</em> as an index in
<em>EX(call_slots)</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Added <em>op_array->used_stack</em>, which is calculated at
compile time; the corresponding stack space is preallocated together with
<em>execute_data</em>. As a result, the ZEND_SEND* and
ZEND_DO_FCALL* opcodes no longer need to check for stack overflow.
</span>
</li>
<li class="listitem">
<span class="simpara">
Removed <em>execute_data->Ts</em> field. The VM temporary
variables are always allocated immediately before the
<em>execute_data</em> structure, and are now accessed by their
offset from the <em>execute_data</em> base pointer instead of
via <em>execute_data->Ts</em>. The compiler stores new
offsets in <em>op_array->opcodes[*].op?.num</em>. The
<strong class="command">EX_TMP_VAR()</strong> and <strong class="command">EX_TMP_VAR_NUM()</strong>
macros can be used to access temporary variables by offset or number. You
can convert the number to an offset using <strong class="command">EX_TMP_VAR_NUM(0,
num)</strong> or offset to number using
<strong class="command">(EX_TMP_VAR_NUM(0,0)-EX_TMP_VAR(0,offset))</strong>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Removed the <em>execute_data->CVs</em> field. The VM
compiled variables are always allocated immediately after the
<em>execute_data</em> structure, and are now accessed by the
offset from the <em>execute_data</em> base pointer instead of
via <em>execute_data->CVs</em>. You can use the
<strong class="command">EX_CV_NUM()</strong> macro to access compiled variables by
number.
</span>
</li>
</ul>
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