docs/opcodes/opcode-1b-const-class.html


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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html>

<head>
<title>const-class</title>
<link rel=stylesheet href="opcode.css">
</head>

<body>

<h1>const-class</h1>

<h2>Purpose</h2>

<p>
Move a reference to the class specified by the given index into the specified
register. In the case where the indicated type is primitive, this will store a
reference to the primitive type's degenerate class.
</p>

<h2>Details</h2>

<table class="instruc">
<thead>
<tr>
  <th>Op &amp; Format</th>
  <th>Mnemonic / Syntax</th>
  <th>Arguments</th>
</tr>
</thead>
<tbody>
<tr>
  <td>1c 21c</td>
  <td>const-class vAA, type@BBBB</td>
  <td><code>A:</code> destination register (8 bits)<br/>
    <code>B:</code> type index</td>
</tr>
</tbody>
</table>

<h2>Constraints</h2>

<ul>
  <li>
    A must be a valid register index in the current stack frame.
  </li>
  <li>
    B must be a valid index into the type constant pool.
  </li>
</ul>

<h2>Behavior</h2>

<ul>
  <li>
    An attempt is made to get a reference to the class C the name of which is
    contained in type pool entry B.
  </li>
  <li>
    If B refers to a primitive type, the corresponding degenerate class is used
    instead.
  </li>
  <li>
    If C has not been loaded and resolved before, it is being loaded and
    resolved. All exceptions that are possible during class loading can occur at
    this point.
  </li>
  <li>
    A reference to C is moved into register vA, that is, vA' = C.
  </li>
  <li>
    If v(A-1) is the lower half of a register pair, v(A-1)' becomes undefined.
  </li>
  <li>
    If v(A+1) is the upper half of a register pair, v(A+1)' becomes undefined.
  </li>
</ul>

<h2>Exceptions</h2>

<ul>
  <li>
    ClassNotFoundException is thrown if the class does not exist at all.
  </li>
  <li>
    VerifyError is thrown if the class does exist, but could not be verified.
  </li>
</ul>

</body>
</html>