println("trap in unknown function", funcname(f))
		return false
	}
	if !sigctxtAtTrapInstruction(ctxt) {
		println("trap at non-INT3 instruction pc =", hex(ctxt.sigpc()))
		return false
	}

	switch status := sigctxtStatus(ctxt); status {
	case 0:
		// Frame is ready. Copy the arguments to the frame and to registers.

	// invoke INT3. The debugger should write the argument
	// frame for the call at SP, set up argument registers, push
	// the trapping PC on the stack, set the PC to the function to
	// call, set RDX to point to the closure (if a closure call),
	// and resume execution.
	//
	// If the function returns, this will set R12 to 1 and invoke
	// INT3. The debugger can then inspect any return value saved

	return int(*(*uint8)(unsafe.Pointer(&x)))
}

// abort crashes the runtime in situations where even throw might not
// work. In general it should do something a debugger will recognize
// (e.g., an INT3 on x86). A crash in abort is recognized by the
// signal handler, which will attempt to tear down the runtime
// immediately.
func abort()

// Called from compiled code; declared for vet; do NOT call from Go.