if b.Kind != BlockIf || p.Kind != BlockIf {
		return false
	}

	// Don't merge control values if b is likely to be bypassed anyway.
	if p.Likely == BranchLikely && p.Succs[0].Block() != b {
		return false
	}
	if p.Likely == BranchUnlikely && p.Succs[1].Block() != b {
		return false
	}

	// Check if the control values combine to make an integer inequality that
	// can be further optimized later.
	bc := b.Controls[0]

				}
				return ret // found
			}

			// Recur
			if ret := search(b.Succs); ret != nil {
				if debug {
					fmt.Printf(" from block %s\n", b)
				}
				return ret
			}
		}
		return nil
	}
	return search(defblock.Succs)
}

func tupleContains(tuple *types.Tuple, v *types.Var) bool {
	for i := 0; i < tuple.Len(); i++ {
		if tuple.At(i) == v {

func (t SparseTree) treestructure(b *Block) string {
	return t.treestructure1(b, 0)
}
func (t SparseTree) treestructure1(b *Block, i int) string {
	s := "\n" + strings.Repeat("\t", i) + b.String() + "->["
	for i, e := range b.Succs {
		if i > 0 {
			s += ","
		}
		s += e.b.String()
	}
	s += "]"
	if c0 := t[b.ID].child; c0 != nil {
		s += "("
		for c := c0; c != nil; c = t[c.ID].sibling {
			if c != c0 {
				s += " "