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},