if span.npages == 1 {
		// This will be inlined and constant-folded down.
		return heapBitsSlice(span.base(), pageSize)
	}
	return heapBitsSlice(span.base(), span.npages*pageSize)
}

// Helper for constructing a slice for the span's heap bits.
//
//go:nosplit
func heapBitsSlice(spanBase, spanSize uintptr) []uintptr {
	bitmapSize := spanSize / goarch.PtrSize / 8