trace.SpanExists(s)

		// Write out allocated objects if it's a heap span.
		if s.state.get() != mSpanInUse {
			continue
		}

		// Find all allocated objects.
		abits := s.allocBitsForIndex(0)
		for i := uintptr(0); i < uintptr(s.nelems); i++ {
			if abits.index < uintptr(s.freeindex) || abits.isMarked() {
				x := s.base() + i*s.elemsize
				trace.HeapObjectExists(x, s.typePointersOfUnchecked(x).typ)
			}

			"puintptr.ptr",
			"spanOf",
			"spanOfUnchecked",
			"typePointers.nextFast",
			"(*gcWork).putFast",
			"(*gcWork).tryGetFast",
			"(*guintptr).set",
			"(*markBits).advance",
			"(*mspan).allocBitsForIndex",
			"(*mspan).base",
			"(*mspan).markBitsForBase",
			"(*mspan).markBitsForIndex",
			"(*mspan).writeUserArenaHeapBits",
			"(*muintptr).set",
			"(*puintptr).set",
			"(*wbBuf).get1",
			"(*wbBuf).get2",

		spanHasNoSpecials(s)
	}

	if traceAllocFreeEnabled() || debug.clobberfree != 0 || raceenabled || msanenabled || asanenabled {
		// Find all newly freed objects.
		mbits := s.markBitsForBase()
		abits := s.allocBitsForIndex(0)
		for i := uintptr(0); i < uintptr(s.nelems); i++ {
			if !mbits.isMarked() && (abits.index < uintptr(s.freeindex) || abits.isMarked()) {
				x := s.base() + i*s.elemsize
				if traceAllocFreeEnabled() {

// We maintain one set of mark bits for allocation and one for
// marking purposes.
type markBits struct {
	bytep *uint8
	mask  uint8
	index uintptr
}

//go:nosplit
func (s *mspan) allocBitsForIndex(allocBitIndex uintptr) markBits {
	bytep, mask := s.allocBits.bitp(allocBitIndex)
	return markBits{bytep, mask, allocBitIndex}
}

// refillAllocCache takes 8 bytes s.allocBits starting at whichByte