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| <head> |
| <title>iget<kind></title> |
| <link rel=stylesheet href="opcode.css"> |
| </head> |
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| <body> |
| |
| <h1>iget<kind></h1> |
| |
| <h2>Purpose</h2> |
| |
| <p> |
| Perform the identified object instance field operation with the identified |
| field, loading or storing into the value register. |
| </p> |
| <p> |
| Note: These opcodes are reasonable candidates for static linking, altering the |
| field argument to be a more direct offset. |
| </p> |
| |
| <h2>Details</h2> |
| |
| <table class="instruc"> |
| <thead> |
| <tr> |
| <th>Op & Format</th> |
| <th>Mnemonic / Syntax</th> |
| <th>Arguments</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td>52..58 22c</td> |
| <td>i<i>instanceop</i> vA, vB, field@CCCC<br/> |
| 52: iget<br/> |
| 53: iget-wide<br/> |
| 54: iget-object<br/> |
| 55: iget-boolean<br/> |
| 56: iget-byte<br/> |
| 57: iget-char<br/> |
| 58: iget-short<br/> |
| </td> |
| <td><code>A:</code> dest value register or pair; (4 bits)<br/> |
| <code>B:</code> object register (4 bits)<br/> |
| <code>C:</code> instance field reference index (16 bits)</td> |
| </tr> |
| </tbody> |
| </table> |
| |
| <h2>Constraints</h2> |
| |
| <ul> |
| <li> |
| A and B must be valid register indices in the current stackframe. |
| </li> |
| <li> |
| For the -wide variant, also A+1 must be a valid register index in the |
| current stackframe. |
| </li> |
| <li> |
| Register vB must contain an object reference. |
| </li> |
| <li> |
| C must be a valid index into the field reference pool. |
| </li> |
| <li> |
| The field must be an instance field. The type of the field denoted by C must |
| match the variant of the instruction. |
| </li> |
| </ul> |
| |
| <h2>Behavior</h2> |
| |
| <ul> |
| <li> |
| The value of the given instance field is read from the given object and |
| moved into the given register vA, that is, vA'=<object>.<field>. |
| </li> |
| <li> |
| If v(A-1) is the lower half of a register pair, v(A-1)' becomes undefined. |
| </li> |
| <li>For all but the -wide variant, if v(A+1) is the upper half of a register |
| pair, v(A+1)' becomes undefined. |
| </li> |
| <li> |
| For the -wide variant, if v(A+2) is the upper half of a register pair, |
| v(A+2)' becomes undefined. |
| </li> |
| </ul> |
| |
| <h2>Exceptions</h2> |
| |
| <ul> |
| <li> |
| NullPointerException if object is null. |
| </li> |
| <li> |
| IllegalAccessException if <object>.<field> is not visible from |
| the current context according to the usual visibility and access rules of |
| the Java programming language. |
| </li> |
| </ul> |
| |
| </body> |
| </html> |
