// No locking needed because it is per-thread (per-P).
//
// mcaches are allocated from non-GC'd memory, so any heap pointers
// must be specially handled.
type mcache struct {
	_ sys.NotInHeap

	// The following members are accessed on every malloc,
	// so they are grouped here for better caching.
	nextSample uintptr // trigger heap sample after allocating this many bytes

	return ht
}

// reset clears the headTailIndex to (0, 0).
func (h *atomicHeadTailIndex) reset() {
	h.u.Store(0)
}

// atomicMSpanPointer is an atomic.Pointer[mspan]. Can't use generics because it's NotInHeap.
type atomicMSpanPointer struct {
	p atomic.UnsafePointer
}

// Load returns the *mspan.
func (p *atomicMSpanPointer) Load() *mspan {
	return (*mspan)(p.p.Load())
}

// Store stores an *mspan.

// avoid contending on the global work buffer lists.

type workbufhdr struct {
	node lfnode // must be first
	nobj int
}

type workbuf struct {
	_ sys.NotInHeap
	workbufhdr
	// account for the above fields
	obj [(_WorkbufSize - unsafe.Sizeof(workbufhdr{})) / goarch.PtrSize]uintptr
}

// workbuf factory routines. These funcs are used to manage the
// workbufs.

	obj := scope.Lookup(name)
	if obj != nil && obj.Type() == nil {
		p.errorf("%v has nil type", obj)
	}

	if p.tok == scanner.Ident && p.lit == "notinheap" {
		p.next()
		// The go/types package has no way of recording that
		// this type is marked notinheap. Presumably no user
		// of this package actually cares.
	}

	// type alias
	if p.tok == '=' {
		p.next()

  reused by the same fixalloc pool, so it can only be reused for
  objects of the same type.

In general, types that are allocated using any of these should be
marked as not in heap by embedding `runtime/internal/sys.NotInHeap`.

Objects that are allocated in unmanaged memory **must not** contain
heap pointers unless the following rules are also obeyed:

1. Any pointers from unmanaged memory to the heap must be garbage

// must be specially handled. GC currently assumes that the finalizer
// queue does not grow during marking (but it can shrink).
type finblock struct {
	_       sys.NotInHeap
	alllink *finblock
	next    *finblock
	cnt     uint32
	_       int32
	fin     [(_FinBlockSize - 2*goarch.PtrSize - 2*4) / unsafe.Sizeof(finalizer{})]finalizer
}

var fingStatus atomic.Uint32

		r := recv.X // the channel
		return mkcall1(chanfn("chanrecv1", 2, r.Type()), nil, init, r, n1)

	case ir.OAPPEND:
		// x = append(...)
		call := as.Y.(*ir.CallExpr)
		if call.Type().Elem().NotInHeap() {
			base.Errorf("%v can't be allocated in Go; it is incomplete (or unallocatable)", call.Type().Elem())
		}
		var r ir.Node
		switch {
		case isAppendOfMake(call):
			// x = append(y, make([]T, y)...)

	if n.X.Type() == nil || n.Y.Type() == nil {
		n.SetType(nil)
		return n
	}
	t := n.X.Type()
	if !t.IsPtr() {
		base.Errorf("first argument to unsafe.Slice must be pointer; have %L", t)
	} else if t.Elem().NotInHeap() {
		// TODO(mdempsky): This can be relaxed, but should only affect the
		// Go runtime itself. End users should only see not-in-heap
		// types due to incomplete C structs in cgo, and those types don't

				checklvalue(n.X, "call pointer method on")
				addr := NodAddr(n.X)
				addr.SetImplicit(true)
				n.X = typecheck(addr, ctxType|ctxExpr)
			} else if tt.IsPtr() && (!rcvr.IsPtr() || rcvr.IsPtr() && rcvr.Elem().NotInHeap()) && types.Identical(tt.Elem(), rcvr) {
				star := ir.NewStarExpr(base.Pos, n.X)
				star.SetImplicit(true)
				n.X = typecheck(star, ctxType|ctxExpr)

var stackpool [_NumStackOrders]struct {
	item stackpoolItem
	_    [(cpu.CacheLinePadSize - unsafe.Sizeof(stackpoolItem{})%cpu.CacheLinePadSize) % cpu.CacheLinePadSize]byte
}

type stackpoolItem struct {
	_    sys.NotInHeap
	mu   mutex
	span mSpanList
}

// Global pool of large stack spans.
var stackLarge struct {
	lock mutex
	free [heapAddrBits - pageShift]mSpanList // free lists by log_2(s.npages)
}