fuseLate(fun.f)
	z0, ok := fun.blocks["z0"]
	if !ok || z0.Kind == BlockInvalid {
		t.Errorf("case2 z0 is eliminated, but should not")
	}
}

func BenchmarkFuse(b *testing.B) {
	for _, n := range [...]int{1, 10, 100, 1000, 10000} {
		b.Run(strconv.Itoa(n), func(b *testing.B) {
			c := testConfig(b)

			blocks := make([]bloc, 0, 2*n+3)
			blocks = append(blocks,
				Bloc("entry",

		bid := q[n].bid
		cid := q[n].cid
		q = q[:n]

		// Add block to tour.
		blocks[bid].pos = int32(len(tour))
		tour = append(tour, bid)

		// Proceed down next child edge (if any).
		if cid == 0 {
			// This is our first visit to b. Set its depth.
			blocks[bid].depth = blocks[blocks[bid].parent].depth + 1
			// Then explore its first child.
			cid = blocks[bid].firstChild
		} else {

	Nlink          uint32
	Uid            uint32
	Gid            uint32
	Rdev           int32
	Atim           Timespec
	Mtim           Timespec
	Ctim           Timespec
	Size           int64
	Blocks         int64
	Blksize        uint32
	Flags          uint32
	Gen            uint32
	X__st_birthtim Timespec
}

type Statfs_t struct {
	F_flags       uint32
	F_bsize       uint32
	F_iosize      uint32

	Mtim    Timespec
	Ctim    Timespec
	Btim    Timespec
	Size    int64
	Blocks  int64
	Blksize uint32
	Flags   uint32
	Gen     uint32
	Spare   [2]uint32
	_       [4]byte
}

type Statfs_t [0]byte

type Statvfs_t struct {
	Flag        uint64
	Bsize       uint64
	Frsize      uint64
	Iosize      uint64
	Blocks      uint64
	Bfree       uint64
	Bavail      uint64
	Bresvd      uint64

	Mtim    Timespec
	Ctim    Timespec
	Btim    Timespec
	Size    int64
	Blocks  int64
	Blksize uint32
	Flags   uint32
	Gen     uint32
	Spare   [2]uint32
	_       [4]byte
}

type Statfs_t [0]byte

type Statvfs_t struct {
	Flag        uint32
	Bsize       uint32
	Frsize      uint32
	Iosize      uint32
	Blocks      uint64
	Bfree       uint64
	Bavail      uint64
	Bresvd      uint64

	Mtim    Timespec
	Ctim    Timespec
	Btim    Timespec
	Size    int64
	Blocks  int64
	Blksize uint32
	Flags   uint32
	Gen     uint32
	Spare   [2]uint32
	_       [4]byte
}

type Statfs_t [0]byte

type Statvfs_t struct {
	Flag        uint64
	Bsize       uint64
	Frsize      uint64
	Iosize      uint64
	Blocks      uint64
	Bfree       uint64
	Bavail      uint64
	Bresvd      uint64

	Atim    Timespec
	Mtim    Timespec
	Ctim    Timespec
	Btim    Timespec
	Size    int64
	Blocks  int64
	Blksize int32
	Flags   uint32
	Gen     uint64
	Spare   [10]uint64
}

type Statfs_t struct {
	Version     uint32
	Type        uint32
	Flags       uint64
	Bsize       uint64
	Iosize      uint64
	Blocks      uint64
	Bfree       uint64
	Bavail      int64
	Files       uint64
	Ffree       int64

	exit := f.newSparseSet(f.NumBlocks()) // exit blocks
	defer f.retSparseSet(exit)

	// Populate idToBlock and find exit blocks.
	for _, b := range f.Blocks {
		idToBlock[b.ID] = b
		if b.Kind == BlockExit {
			exit.add(b.ID)
		}
	}

	// Expand exit to include blocks post-dominated by exit blocks.
	for {
		changed := false
		for _, id := range exit.contents() {
			b := idToBlock[id]
		NextPred:

	for i, b := range f.Blocks {
		idToIdx[b.ID] = i
	}

	// Set of blocks we're moving, by ID.
	move := map[ID]struct{}{}

	// Map from block ID to the moving blocks that should
	// come right after it.
	after := map[ID][]*Block{}

	// Check each loop header and decide if we want to move it.
	for _, loop := range loopnest.loops {
		b := loop.header
		var p *Block // b's in-loop predecessor

	Uid           uint32
	Gid           uint32
	Pad_cgo_1     [4]byte
	Rdev          uint64
	Atimespec     Timespec
	Mtimespec     Timespec
	Ctimespec     Timespec
	Birthtimespec Timespec
	Size          int64
	Blocks        int64
	Blksize       uint32
	Flags         uint32
	Gen           uint32
	Spare         [2]uint32
	Pad_cgo_2     [4]byte
}

type Statfs_t [0]byte

type Flock_t struct {
	Start  int64