t.Skip("-quick")
	}
	testenv.MustHaveGoBuild(t)

	testprog.Lock()
	if testprog.dir == "" {
		dir, err := os.MkdirTemp("", "go-build")
		if err != nil {
			t.Fatalf("failed to create temp directory: %v", err)
		}
		testprog.dir = dir
		toRemove = append(toRemove, dir)
	}

	if testprog.target == nil {
		testprog.target = make(map[string]*buildexe)
	}
	name := binary
	if len(flags) > 0 {

		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)
	}
}

)

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.MustHaveGoRun(t)

	tmpdir := t.TempDir()

	src := filepath.Join(tmpdir, "a.go")
	file, err := os.Create(src)
	if err != nil {
		t.Fatal(err)
	}
	err = template.Must(template.New("main").Parse(testprog)).Execute(file, linktype != linkNoCgo)
	if err != nil {
		if err := file.Close(); err != nil {
			t.Error(err)
		}
		t.Fatal(err)
	}
	if err := file.Close(); err != nil {
		t.Fatal(err)
	}

		type frame struct {
			fn   string
			line int
		}
		type evDesc struct {
			kind   trace.EventKind
			match  string
			frames []frame
		}
		// mainLine is the line number of `func main()` in testprog/stacks.go.
		const mainLine = 21
		want := []evDesc{
			{trace.EventStateTransition, "Goroutine Running->Runnable", []frame{
				{"main.main", mainLine + 82},
			}},

		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")

	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

func GCMemoryLimitNoGCPercent() {
	gcMemoryLimit(-1)
}

// Test SetMemoryLimit functionality.
//
// This test lives here instead of runtime/debug because the entire
// implementation is in the runtime, and testprog gives us a more
// consistent testing environment to help avoid flakiness.
func gcMemoryLimit(gcPercent int) {
	if oldProcs := runtime.GOMAXPROCS(4); oldProcs < 4 {
		// Fail if the default GOMAXPROCS isn't at least 4.

		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) {