func invertPallocBits(b *PallocBits) {
	for i := range b {
		b[i] = ^b[i]
	}
}

// Ensures two packed summaries are identical, and reports a detailed description
// of the difference if they're not.
func checkPallocSum(t testing.TB, got, want PallocSum) {
	if got.Start() != want.Start() {
		t.Errorf("inconsistent start: got %d, want %d", got.Start(), want.Start())
	}
	if got.Max() != want.Max() {