<function name="attach" parent="jit" type="libraryfunc"> <description> You can attach callbacks to a number of compiler events with jit.attach. The callback can be called: * when a function has been compiled to bytecode (`"bc"`); * when trace recording starts or stops (`"trace"`); * as a trace is being recorded (`"record"`); * or when a trace exits through a side exit (`"texit"`). Set a callback with `jit.attach(callback, "event")` and clear the same callback with `jit.attach(callback)`⤶ Set a callback with `jit.attach(callback, "event")` and clear the same callback with `jit.attach(callback)`.⤶ Only one callback can be active per event.⤶ <warning>This function isn't officially documented on LuaJIT wiki, use it at your own risk.</warning> <warning>Using these constantly (especially bytecode) can be very performance heavy due to the constant stream of data being compiled at a time.</warning>⤶ </description> <realm>Shared and Menu</realm> <args> <arg name="callback" type="function">The callback function. The arguments passed to the callback depend on the event being reported: * `"bc"`: * <page>function</page> **func** - The function that's just been recorded * `"trace"`: * <page>string</page> **what** - description of the trace event: "flush", "start", "stop", "abort". Available for all events. * <page>number</page> **tr** - The trace number. Not available for flush. * <page>function</page> **func** - The function being traced. Available for start and abort. * <page>number</page> **pc** - The program counter - the bytecode number of the function being recorded (if this a Lua function). Available for start and abort. * <page>number</page> **otr** - start: the parent trace number if this is a side trace, abort: abort code * <page>string</page> **oex** - start: the exit number for the parent trace, abort: abort reason (string) * `"record"`: * <page>number</page> **tr** - The trace number. Not available for flush. * <page>function</page> **func** - The function being traced. Available for start and abort. * <page>number</page> **pc** - The program counter - the bytecode number of the function being recorded (if this a Lua function). Available for start and abort. * <page>number</page> **depth** - The depth of the inlining of the current bytecode. * `"texit"`: * <page>number</page> **tr** - The trace number. Not available for flush. * <page>number</page> **ex** - The exit number * <page>number</page> **ngpr** - The number of general-purpose and floating point registers that are active at the exit. * <page>number</page> **nfpr** - The number of general-purpose and floating point registers that are active at the exit. </arg> <arg name="event" type="string">The event to hook into.</arg> </args> </function>