// and the compiler does not emit write barriers for assignments
// of gclinkptr values. Code should store references to gclinks
// as gclinkptr, not as *gclink.
type gclink struct {
	next gclinkptr
}

// A gclinkptr is a pointer to a gclink, but it is opaque
// to the garbage collector.
type gclinkptr uintptr

// ptr returns the *gclink form of p.

	log2 := 0
	for n > 1 {
		n >>= 1
		log2++
	}
	return log2
}

// Allocates a stack from the free pool. Must be called with
// stackpool[order].item.mu held.
func stackpoolalloc(order uint8) gclinkptr {
	list := &stackpool[order].item.span
	s := list.first
	lockWithRankMayAcquire(&mheap_.lock, lockRankMheap)
	if s == nil {
		// no free stacks. Allocate another span worth.

			"stringStructOf",
			"subtract1",
			"subtractb",
			"tophash",
			"(*bmap).keys",
			"(*bmap).overflow",
			"(*waitq).enqueue",
			"funcInfo.entry",

			// GC-related ones
			"cgoInRange",
			"gclinkptr.ptr",
			"guintptr.ptr",
			"heapBitsSlice",
			"markBits.isMarked",
			"muintptr.ptr",
			"puintptr.ptr",
			"spanOf",
			"spanOfUnchecked",
			"typePointers.nextFast",
			"(*gcWork).putFast",

	}
}

// base address for all 0-byte allocations
var zerobase uintptr

// nextFreeFast returns the next free object if one is quickly available.
// Otherwise it returns 0.
func nextFreeFast(s *mspan) gclinkptr {
	theBit := sys.TrailingZeros64(s.allocCache) // Is there a free object in the allocCache?
	if theBit < 64 {
		result := s.freeindex + uint16(theBit)
		if result < s.nelems {
			freeidx := result + 1

	list *mSpanList // For debugging.

	startAddr uintptr // address of first byte of span aka s.base()
	npages    uintptr // number of pages in span

	manualFreeList gclinkptr // list of free objects in mSpanManual spans

	// freeindex is the slot index between 0 and nelems at which to begin scanning
	// for the next free object in this span.