after  uintptr
	}
	var m uint64 = magic64
	magicptr := uintptr(m)
	x.before = magicptr
	x.after = magicptr
	for delta := uintptr(1); delta+delta > delta; delta += delta {
		k := LoadUintptr(&x.i)
		if k != x.i {
			t.Fatalf("delta=%d i=%d k=%d", delta, x.i, k)
		}
		x.i += delta
	}
	if x.before != magicptr || x.after != magicptr {

//go:linkname abigen_sync_atomic_LoadUint64 sync/atomic.LoadUint64
func abigen_sync_atomic_LoadUint64(addr *uint64) (val uint64)

//go:linkname abigen_sync_atomic_LoadUintptr sync/atomic.LoadUintptr
func abigen_sync_atomic_LoadUintptr(addr *uintptr) (val uintptr)

//go:linkname abigen_sync_atomic_LoadPointer sync/atomic.LoadPointer
func abigen_sync_atomic_LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)

func (h *mheap) allocNeedsZero(base, npage uintptr) (needZero bool) {
	for npage > 0 {
		ai := arenaIndex(base)
		ha := h.arenas[ai.l1()][ai.l2()]

		zeroedBase := atomic.Loaduintptr(&ha.zeroedBase)
		arenaBase := base % heapArenaBytes
		if arenaBase < zeroedBase {
			// We extended into the non-zeroed part of the
			// arena, so this region needs to be zeroed before use.
			//

	thisg.m.morebuf.g = 0

	// NOTE: stackguard0 may change underfoot, if another thread
	// is about to try to preempt gp. Read it just once and use that same
	// value now and below.
	stackguard0 := atomic.Loaduintptr(&gp.stackguard0)

	// Be conservative about where we preempt.
	// We are interested in preempting user Go code, not runtime code.
	// If we're holding locks, mallocing, or preemption is disabled, don't

// persistentalloc. This must be nosplit because it is called by the
// cgo checker code, which is called by the write barrier code.
//
//go:nosplit
func inPersistentAlloc(p uintptr) bool {
	chunk := atomic.Loaduintptr((*uintptr)(unsafe.Pointer(&persistentChunks)))
	for chunk != 0 {
		if p >= chunk && p < chunk+persistentChunkSize {
			return true
		}
		chunk = *(*uintptr)(unsafe.Pointer(chunk))
	}
	return false

	return allgs[:len(allgs):len(allgs)]
}

// atomicAllG returns &allgs[0] and len(allgs) for use with atomicAllGIndex.
func atomicAllG() (**g, uintptr) {
	length := atomic.Loaduintptr(&allglen)
	ptr := (**g)(atomic.Loadp(unsafe.Pointer(&allgptr)))
	return ptr, length
}

// atomicAllGIndex returns ptr[i] with the allgptr returned from atomicAllG.
func atomicAllGIndex(ptr **g, i uintptr) *g {

	alias("internal/runtime/atomic", "Loadint64", "internal/runtime/atomic", "Load64", all...)
	alias("internal/runtime/atomic", "Loaduintptr", "internal/runtime/atomic", "Load", p4...)
	alias("internal/runtime/atomic", "Loaduintptr", "internal/runtime/atomic", "Load64", p8...)
	alias("internal/runtime/atomic", "Loaduint", "internal/runtime/atomic", "Load", p4...)

		tp.elem += tp.typ.Size_
		tp.addr = tp.elem
		tp.mask = readUintptr(tp.typ.GCData)

		// We may have exceeded the limit after this. Bail just like next does.
		if tp.addr >= limit {
			return typePointers{}
		}
	} else {
		// Grab the mask, but then clear any bits before the target address and any
		// bits over the limit.
		tp.mask = readUintptr(addb(tp.typ.GCData, (tp.addr-tp.elem)/goarch.PtrSize/8))

		// a platform-ordered way for efficiency, but stores back the
		// data in little endian order, since we expose the bitmap through
		// a dummy type.
		h = h.write(s, readUintptr(addb(p, i/8)), k)
	}
	// Note: we call pad here to ensure we emit explicit 0 bits
	// for the pointerless tail of the object. This ensures that
	// there's only a single noMorePtrs mark for the next object