println("second alloc: expected delta at least 9MB, got: ", delta)
	}
	runtime.KeepAlive(x)
}

func main() {
	x := inuse()
	f(new(big), x)
}

func inuse() int64 {
	runtime.GC()
	var st runtime.MemStats
	runtime.ReadMemStats(&st)
	return int64(st.Alloc)

		dumpint(uint64(uintptr(unsafe.Pointer(mp))))
		dumpint(uint64(mp.id))
		dumpint(mp.procid)
	}
}

//go:systemstack
func dumpmemstats(m *MemStats) {
	assertWorldStopped()

	// These ints should be identical to the exported
	// MemStats structure and should be ordered the same
	// way too.
	dumpint(tagMemStats)
	dumpint(m.Alloc)
	dumpint(m.TotalAlloc)
	dumpint(m.Sys)
	dumpint(m.Lookups)

	*runtime.DoubleCheckReadMemStats = true
}

func TestReadMemStats(t *testing.T) {
	base, slow := runtime.ReadMemStatsSlow()
	if base != slow {
		logDiff(t, "MemStats", reflect.ValueOf(base), reflect.ValueOf(slow))
		t.Fatal("memstats mismatch")
	}
}

func logDiff(t *testing.T, prefix string, got, want reflect.Value) {
	typ := got.Type()
	switch typ.Kind() {
	case reflect.Array, reflect.Slice:

// managed by the Go runtime).
//
// More specifically, the following expression accurately reflects
// the value the runtime attempts to maintain as the limit:
//
//	runtime.MemStats.Sys - runtime.MemStats.HeapReleased
//
// or in terms of the runtime/metrics package:
//
//	/memory/classes/total:bytes - /memory/classes/heap/released:bytes
//
// A zero limit or a limit that's lower than the amount of memory

	"time"
	"unsafe"
)

var testMemStatsCount int

func TestMemStats(t *testing.T) {
	testMemStatsCount++

	// Make sure there's at least one forced GC.
	GC()

	// Test that MemStats has sane values.
	st := new(MemStats)
	ReadMemStats(st)

	nz := func(x any) error {
		if x != reflect.Zero(reflect.TypeOf(x)).Interface() {
			return nil
		}
		return fmt.Errorf("zero value")
	}

}

func writeHeapInternal(w io.Writer, debug int, defaultSampleType string) error {
	var memStats *runtime.MemStats
	if debug != 0 {
		// Read mem stats first, so that our other allocations
		// do not appear in the statistics.
		memStats = new(runtime.MemStats)
		runtime.ReadMemStats(memStats)
	}

	// Find out how many records there are (MemProfile(nil, true)),

	h.cachealloc.init(unsafe.Sizeof(mcache{}), nil, nil, &memstats.mcache_sys)
	h.specialfinalizeralloc.init(unsafe.Sizeof(specialfinalizer{}), nil, nil, &memstats.other_sys)
	h.specialprofilealloc.init(unsafe.Sizeof(specialprofile{}), nil, nil, &memstats.other_sys)
	h.specialReachableAlloc.init(unsafe.Sizeof(specialReachable{}), nil, nil, &memstats.other_sys)

//go:noinline
func withoutNoEscape() {
	var str string
	C.runCWithoutNoEscape(unsafe.Pointer(&str))
}

func CgoNoEscape() {
	// make GC stop to see the heap objects allocated
	debug.SetGCPercent(-1)

	var stats runtime.MemStats
	runtime.ReadMemStats(&stats)
	preHeapObjects := stats.HeapObjects

	for i := 0; i < num; i++ {
		withNoEscape()
	}

	runtime.ReadMemStats(&stats)
	nowHeapObjects := stats.HeapObjects

	metricsUnlock()

	startTheWorld(stw)
}

var DoubleCheckReadMemStats = &doubleCheckReadMemStats

// ReadMemStatsSlow returns both the runtime-computed MemStats and
// MemStats accumulated by scanning the heap.
func ReadMemStatsSlow() (base, slow MemStats) {
	stw := stopTheWorld(stwForTestReadMemStatsSlow)

	// Run on the system stack to avoid stack growth allocation.
	systemstack(func() {

		arena := mheap_.arenas[ai.l1()][ai.l2()]
		bitmap := arena.checkmarks

		if bitmap == nil {
			// Allocate bitmap on first use.
			bitmap = (*checkmarksMap)(persistentalloc(unsafe.Sizeof(*bitmap), 0, &memstats.gcMiscSys))
			if bitmap == nil {
				throw("out of memory allocating checkmarks bitmap")
			}
			arena.checkmarks = bitmap
		} else {
			// Otherwise clear the existing bitmap.
			clear(bitmap.b[:])
		}
	}