t.Skip("Skipping in short mode") // takes up to 64 seconds
	}
	got := runTestProg(t, "testprogcgo", "CgoSignalDeadlock")
	want := "OK\n"
	if got != want {
		t.Fatalf("expected %q, but got:\n%s", want, got)
	}
}

func TestCgoTraceback(t *testing.T) {
	t.Parallel()
	got := runTestProg(t, "testprogcgo", "CgoTraceback")
	want := "OK\n"
	if got != want {

func TestVDSO(t *testing.T) {
	t.Parallel()
	output := runTestProg(t, "testprog", "SignalInVDSO")
	want := "success\n"
	if output != want {
		t.Fatalf("output:\n%s\n\nwanted:\n%s", output, want)
	}
}

func testCrashHandler(t *testing.T, cgo bool) {
	type crashTest struct {
		Cgo bool
	}
	var output string
	if cgo {
		output = runTestProg(t, "testprogcgo", "Crash")
	} else {

	if !runtime.PreemptMSupported {
		t.Skip("asynchronous preemption not supported on this platform")
	}
	output := runTestProg(t, "testprog", "AsyncPreempt")
	want := "OK\n"
	if output != want {
		t.Fatalf("want %s, got %s\n", want, output)
	}
}

func TestGCFairness(t *testing.T) {
	output := runTestProg(t, "testprog", "GCFairness")
	want := "OK\n"
	if output != want {
		t.Fatalf("want %s, got %s\n", want, output)

	"time"
	"unsafe"
)

func TestGcSys(t *testing.T) {
	t.Skip("skipping known-flaky test; golang.org/issue/37331")
	if os.Getenv("GOGC") == "off" {
		t.Skip("skipping test; GOGC=off in environment")
	}
	got := runTestProg(t, "testprog", "GCSys")
	want := "OK\n"
	if got != want {
		t.Fatalf("expected %q, but got %q", want, got)
	}
}

func TestGcDeepNesting(t *testing.T) {
	type T [2][2][2][2][2][2][2][2][2][2]*int
	a := new(T)

	}
}

func TestTracebackAncestors(t *testing.T) {
	goroutineRegex := regexp.MustCompile(`goroutine [0-9]+ \[`)
	for _, tracebackDepth := range []int{0, 1, 5, 50} {
		output := runTestProg(t, "testprog", "TracebackAncestors", fmt.Sprintf("GODEBUG=tracebackancestors=%d", tracebackDepth))

		numGoroutines := 3
		numFrames := 2
		ancestorsExpected := numGoroutines
		if numGoroutines > tracebackDepth {

		testenv.SkipFlaky(t, 49681)
	}
	o := runTestProg(t, "testprog", "RaiseException")
	if strings.Contains(o, "RaiseException should not return") {
		t.Fatalf("RaiseException did not crash program: %v", o)
	}
	if !strings.Contains(o, "Exception 0xbad") {
		t.Fatalf("No stack trace: %v", o)
	}
}

func TestZeroDivisionException(t *testing.T) {
	o := runTestProg(t, "testprog", "ZeroDivisionException")

			}
		}
		b = append(b, 0)
		r := runtime.GostringW(b)
		if r != s {
			t.Errorf("gostringW(%v) = %s, want %s", b, r, s)
		}
	}
}

func TestLargeStringConcat(t *testing.T) {
	output := runTestProg(t, "testprog", "stringconcat")
	want := "panic: " + strings.Repeat("0", 1<<10) + strings.Repeat("1", 1<<10) +
		strings.Repeat("2", 1<<10) + strings.Repeat("3", 1<<10)
	if !strings.HasPrefix(output, want) {

	leaked := PageCachePagesLeaked()
	if leaked != 0 {
		t.Fatalf("found %d leaked pages in page caches", leaked)
	}
}

func TestPhysicalMemoryUtilization(t *testing.T) {
	got := runTestProg(t, "testprog", "GCPhys")
	want := "OK\n"
	if got != want {
		t.Fatalf("expected %q, but got %q", want, got)
	}
}

func TestScavengedBitsCleared(t *testing.T) {
	var mismatches [128]BitsMismatch