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| <a name="Interacting-with-the-GCC-Garbage-Collector"></a> |
| <h3 class="section">23.4 Interacting with the GCC Garbage Collector</h3> |
| |
| <p>Some plugins may want to be informed when GGC (the GCC Garbage |
| Collector) is running. They can register callbacks for the |
| <code>PLUGIN_GGC_START</code> and <code>PLUGIN_GGC_END</code> events (for which |
| the callback is called with a null <code>gcc_data</code>) to be notified of |
| the start or end of the GCC garbage collection. |
| </p> |
| <p>Some plugins may need to have GGC mark additional data. This can be |
| done by registering a callback (called with a null <code>gcc_data</code>) |
| for the <code>PLUGIN_GGC_MARKING</code> event. Such callbacks can call the |
| <code>ggc_set_mark</code> routine, preferably through the <code>ggc_mark</code> macro |
| (and conversely, these routines should usually not be used in plugins |
| outside of the <code>PLUGIN_GGC_MARKING</code> event). |
| </p> |
| <p>Some plugins may need to add extra GGC root tables, e.g. to handle their own |
| <code>GTY</code>-ed data. This can be done with the <code>PLUGIN_REGISTER_GGC_ROOTS</code> |
| pseudo-event with a null callback and the extra root table (of type <code>struct |
| ggc_root_tab*</code>) as <code>user_data</code>. Plugins that want to use the |
| <code>if_marked</code> hash table option can add the extra GGC cache tables generated |
| by <code>gengtype</code> using the <code>PLUGIN_REGISTER_GGC_CACHES</code> pseudo-event with |
| a null callback and the extra cache table (of type <code>struct ggc_cache_tab*</code>) |
| as <code>user_data</code>. Running the <code>gengtype -p <var>source-dir</var> |
| <var>file-list</var> <var>plugin*.c</var> ...</code> utility generates these extra root tables. |
| </p> |
| <p>You should understand the details of memory management inside GCC |
| before using <code>PLUGIN_GGC_MARKING</code>, <code>PLUGIN_REGISTER_GGC_ROOTS</code> |
| or <code>PLUGIN_REGISTER_GGC_CACHES</code>. |
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