func (b *Block) removeSucc(i int) {
	n := len(b.Succs) - 1
	if i != n {
		e := b.Succs[n]
		b.Succs[i] = e
		// Update the other end of the edge we moved.
		e.b.Preds[e.i].i = i
	}
	b.Succs[n] = Edge{}
	b.Succs = b.Succs[:n]
	b.Func.invalidateCFG()
}

func (b *Block) swapSuccessors() {
	if len(b.Succs) != 2 {
		b.Fatalf("swapSuccessors with len(Succs)=%d", len(b.Succs))
	}
	e0 := b.Succs[0]

	case ssa.BlockPlain:
		if next != b.Succs[0].Block() {
			s.Br(obj.AJMP, b.Succs[0].Block())
		}

	case ssa.BlockIf:
		switch next {
		case b.Succs[0].Block():
			// if false, jump to b.Succs[1]
			getValue32(s, b.Controls[0])
			s.Prog(wasm.AI32Eqz)
			s.Prog(wasm.AIf)
			s.Br(obj.AJMP, b.Succs[1].Block())
			s.Prog(wasm.AEnd)
		case b.Succs[1].Block():
			// if true, jump to b.Succs[0]

		// reverse is the predecessor from which the truth value comes.
		var reverse int
		if b0.Succs[0].b == pb0 && b0.Succs[1].b == pb1 {
			reverse = 0
		} else if b0.Succs[0].b == pb1 && b0.Succs[1].b == pb0 {
			reverse = 1
		} else {
			b.Fatalf("invalid predecessors\n")
		}

		for _, v := range b.Values {
			if v.Op != OpPhi {
				continue
			}

			// Look for conversions from bool to 0/1.

// Z:
// 	return y
// }

// {f:BC_CD_BE_BZ_CZ101,
//  maxin:32, blocks:[]blo{
//  	blo{inc:0, cond:true, succs:[2]int64{1, 2}},
//  	blo{inc:1, cond:true, succs:[2]int64{2, 3}},
//  	blo{inc:0, cond:true, succs:[2]int64{1, 4}},
//  	blo{inc:10, cond:true, succs:[2]int64{1, 25}},
//  	blo{inc:0, cond:true, succs:[2]int64{2, 25}},}},

var labels string = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

		// order, in which the predecessors edges are merged here.
		p, i := b.Preds[0].b, b.Preds[0].i
		s, j := b.Succs[0].b, b.Succs[0].i
		ns := len(s.Preds)
		p.Succs[i] = Edge{s, j}
		s.Preds[j] = Edge{p, i}

		for _, e := range b.Preds[1:] {
			p, i := e.b, e.i
			p.Succs[i] = Edge{s, len(s.Preds)}
			s.Preds = append(s.Preds, Edge{p, i})
		}

		// Attempt to preserve a statement boundary
		if bIsStmt {

				// Don't increment i in this case because we moved
				// an unprocessed predecessor down into slot i.
			} else {
				// splice it in
				p.Succs[pi] = Edge{d, 0}
				b.Preds[i] = Edge{d, 0}
				d.Preds = append(d.Preds, Edge{p, pi})
				d.Succs = append(d.Succs, Edge{b, i})
				i++
			}
		}
	}

	// Check if newsuccs is the same set as succs.
	succs := s[data.controls:]
	newsuccs := t[outdata.controls:]
	m := map[string]bool{}
	for _, succ := range succs {
		if m[succ] {
			log.Fatalf("can't have a repeat successor name %s in %s", succ, rule)
		}
		m[succ] = true
	}
	for _, succ := range newsuccs {
		if !m[succ] {
			log.Fatalf("unknown successor %s in %s", succ, rule)
		}
		delete(m, succ)
	}

				ft.restore()
				if !unsat {
					continue
				}
				// This branch is impossible,so redirect p directly to another branch.
				out := 1 ^ j
				child := parent.Succs[out].b
				if child == b {
					continue
				}
				b.removePred(k)
				p.Succs[pk.i] = Edge{child, len(child.Preds)}
				// Fix up Phi value in b to have one less argument.
				for _, v := range b.Values {
					if v.Op != OpPhi {
						continue
					}

}

// removeEdge removes the i'th outgoing edge from b (and
// the corresponding incoming edge from b.Succs[i].b).
// Note that this potentially reorders successors of b, so it
// must be used very carefully.
func (b *Block) removeEdge(i int) {
	e := b.Succs[i]
	c := e.b
	j := e.i

	// Adjust b.Succs
	b.removeSucc(i)

	// Adjust c.Preds
	c.removePred(j)

	// Remove phi args from c's phis.

	// whether a block has already been emitted. In general forward
	// branches are assumed 'not taken' and backward branches are
	// assumed 'taken'.
	if next == succs[0] {
		succs[0], succs[1] = succs[1], succs[0]
		mask = mask.Inverse()
	}

	p := s.Br(blockAsm(b), succs[0])
	switch b.Kind {
	case ssa.BlockS390XBRC:
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = int64(mask)
	case ssa.BlockS390XCGRJ, ssa.BlockS390XCRJ,