func CountPagesInUse() (pagesInUse, counted uintptr) {
	stw := stopTheWorld(stwForTestCountPagesInUse)

	pagesInUse = mheap_.pagesInUse.Load()

	for _, s := range mheap_.allspans {
		if s.state.get() == mSpanInUse {
			counted += s.npages
		}
	}

	startTheWorld(stw)

	return
}

func Fastrand() uint32          { return uint32(rand()) }
func Fastrand64() uint64        { return rand() }

		"-ex", "set startup-with-shell off",
		"-ex", "break main.main",
		"-ex", "run",
		"-ex", "print main.aConstant",
		"-ex", "print main.largeConstant",
		"-ex", "print main.minusOne",
		"-ex", "print 'runtime.mSpanInUse'",
		"-ex", "print 'runtime._PageSize'",
		filepath.Join(dir, "a.exe"),
	}
	gdbArgsFixup(args)
	got, err := exec.Command("gdb", args...).CombinedOutput()
	t.Logf("gdb output:\n%s", got)
	if err != nil {

			// about the span being freed and re-used.
			s := ha.spans[arenaPage+uint(i)*8+j]

			// The state must be mSpanInUse if the specials bit is set, so
			// sanity check that.
			if state := s.state.get(); state != mSpanInUse {
				print("s.state = ", state, "\n")
				throw("non in-use span found with specials bit set")
			}

	fmt.Fprintf(w, "# HeapReleased = %d\n", s.HeapReleased)
	fmt.Fprintf(w, "# HeapObjects = %d\n", s.HeapObjects)

	fmt.Fprintf(w, "# Stack = %d / %d\n", s.StackInuse, s.StackSys)
	fmt.Fprintf(w, "# MSpan = %d / %d\n", s.MSpanInuse, s.MSpanSys)
	fmt.Fprintf(w, "# MCache = %d / %d\n", s.MCacheInuse, s.MCacheSys)
	fmt.Fprintf(w, "# BuckHashSys = %d\n", s.BuckHashSys)
	fmt.Fprintf(w, "# GCSys = %d\n", s.GCSys)

	// useful to couple these stats more tightly to the gcController, which
	// is intimately connected to how that memory limit is maintained.
	heapInUse    sysMemStat    // bytes in mSpanInUse spans
	heapReleased sysMemStat    // bytes released to the OS
	heapFree     sysMemStat    // bytes not in any span, but not released to the OS
	totalAlloc   atomic.Uint64 // total bytes allocated

		{"MemStats.HeapSys", Field, 0},
		{"MemStats.LastGC", Field, 0},
		{"MemStats.Lookups", Field, 0},
		{"MemStats.MCacheInuse", Field, 0},
		{"MemStats.MCacheSys", Field, 0},
		{"MemStats.MSpanInuse", Field, 0},
		{"MemStats.MSpanSys", Field, 0},
		{"MemStats.Mallocs", Field, 0},
		{"MemStats.NextGC", Field, 0},
		{"MemStats.NumForcedGC", Field, 8},
		{"MemStats.NumGC", Field, 0},

pkg runtime, type MemStats struct, Lookups uint64
pkg runtime, type MemStats struct, MCacheInuse uint64
pkg runtime, type MemStats struct, MCacheSys uint64
pkg runtime, type MemStats struct, MSpanInuse uint64
pkg runtime, type MemStats struct, MSpanSys uint64
pkg runtime, type MemStats struct, Mallocs uint64
pkg runtime, type MemStats struct, NextGC uint64
pkg runtime, type MemStats struct, NumGC uint32