// make room for args and g
	SUBL	$24, SP

	// save g
	MOVL	g(AX), BP
	MOVL	BP, 20(SP)

	// g = m->gsignal
	MOVL	m_gsignal(BX), DI
	MOVL	DI, g(AX)

	// load args and call sighandler
	MOVL	CX, 0(SP)
	MOVL	DX, 4(SP)
	MOVL	BP, 8(SP)

	CALL	runtime·sighandler(SB)
	MOVL	12(SP), AX

	// restore g
	get_tls(BX)
	MOVL	20(SP), BP
	MOVL	BP, g(BX)

	// call noted(AX)

   *
   * <pre>{@code
   * static final ImmutableClassToInstanceMap<Handler> HANDLERS =
   *     new ImmutableClassToInstanceMap.Builder<Handler>()
   *         .put(FooHandler.class, new FooHandler())
   *         .put(BarHandler.class, new SubBarHandler())
   *         .put(Handler.class, new QuuxHandler())
   *         .build();
   * }</pre>
   *
   * <p>After invoking {@link #build()} it is still possible to add more entries and build again.

   *
   * <pre>{@code
   * static final ImmutableClassToInstanceMap<Handler> HANDLERS =
   *     new ImmutableClassToInstanceMap.Builder<Handler>()
   *         .put(FooHandler.class, new FooHandler())
   *         .put(BarHandler.class, new SubBarHandler())
   *         .put(Handler.class, new QuuxHandler())
   *         .build();
   * }</pre>
   *
   * <p>After invoking {@link #build()} it is still possible to add more entries and build again.

	// make room for args, retval and g
	SUB	$24, R13

	// save g
	MOVW	g, R3
	MOVW	R3, 20(R13)

	// g = m->gsignal
	MOVW	m_gsignal(R0), g

	// load args and call sighandler
	ADD	$4,R13,R5
	MOVM.IA	[R1-R3], (R5)
	BL	runtime·sighandler(SB)
	MOVW	16(R13), R0			// retval

	// restore g
	MOVW	20(R13), g

	// call noted(R0)
	MOVW	R0, 4(R13)
	BL	runtime·noted(SB)

	recv       [(_NSIG + 31) / 32]uint32
	state      atomic.Uint32
	delivering atomic.Uint32
	inuse      bool
}

const (
	sigIdle = iota
	sigReceiving
	sigSending
)

// sigsend delivers a signal from sighandler to the internal signal delivery queue.
// It reports whether the signal was sent. If not, the caller typically crashes the program.
// It runs from the signal handler, so it's limited in what it can do.