// 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 {

					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
					}
					b.removePhiArg(v, k)
				}
				// Fix up child to have one more predecessor.
				child.Preds = append(child.Preds, Edge{p, pk.i})
				ai := b.Succs[out].i
				for _, v := range child.Values {

			// block, then we need to remove the
			// corresponding elements from the block
			// predecessors and phi args
			if reusedBlock {
				// Add p->d edge
				p.Succs[pi] = Edge{d, len(d.Preds)}
				d.Preds = append(d.Preds, Edge{p, pi})

				// Remove p as a predecessor from b.
				b.removePred(i)

				// Update corresponding phi args
				b.removePhiArg(phi, i)

				// splitting occasionally leads to a phi having

		if bx == c {
			break
		}
		copyTo += len(bx.Values)
	}
	c.Values = t

	// replace b->c edge with preds(b) -> c
	c.predstorage[0] = Edge{}
	if len(b.Preds) > len(b.predstorage) {
		c.Preds = b.Preds
	} else {
		c.Preds = append(c.predstorage[:0], b.Preds...)
	}
	for i, e := range c.Preds {
		p := e.b
		p.Succs[e.i] = Edge{c, i}
	}
	f := b.Func
	if f.Entry == b {
		f.Entry = c
	}

	// in which the outbound paths from b merge,
	// with no other preds joining them.
	// In these cases, we can reconstruct what the value
	// of any phi in b must be in the successor blocks.

	if len(t.Preds) == 1 && len(t.Succs) == 1 &&
		len(u.Preds) == 1 && len(u.Succs) == 1 &&
		t.Succs[0].b == u.Succs[0].b && len(t.Succs[0].b.Preds) == 2 {
		// p   q
		//  \ /
		//   b
		//  / \
		// t   u
		//  \ /

	for _, b := range f.Blocks {
		if len(b.Preds) != 2 || len(b.Values) == 0 {
			// TODO: handle more than 2 predecessors, e.g. a || b || c.
			continue
		}

		pb0, b0 := b, b.Preds[0].b
		for len(b0.Succs) == 1 && len(b0.Preds) == 1 {
			pb0, b0 = b0, b0.Preds[0].b
		}
		if b0.Kind != BlockIf {
			continue
		}
		pb1, b1 := b, b.Preds[1].b
		for len(b1.Succs) == 1 && len(b1.Preds) == 1 {
			pb1, b1 = b1, b1.Preds[0].b
		}

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

// removeSucc removes the ith output edge from b.
// It is the responsibility of the caller to remove

		if b.Func != f {
			f.Fatalf("%s.Func=%s, want %s", b, b.Func.Name, f.Name)
		}

		for i, e := range b.Preds {
			if se := e.b.Succs[e.i]; se.b != b || se.i != i {
				f.Fatalf("block pred/succ not crosslinked correctly %d:%s %d:%s", i, b, se.i, se.b)
			}
		}
		for i, e := range b.Succs {
			if pe := e.b.Preds[e.i]; pe.b != b || pe.i != i {
				f.Fatalf("block succ/pred not crosslinked correctly %d:%s %d:%s", i, b, pe.i, pe.b)
			}

		b.Values = b.Values[:0]
		// The current live flag value (the pre-flagalloc copy).
		var flag *Value
		if len(b.Preds) > 0 {
			flag = end[b.Preds[0].b.ID]
			// Note: the following condition depends on the lack of critical edges.
			for _, e := range b.Preds[1:] {
				p := e.b
				if end[p.ID] != flag {
					f.Fatalf("live flag in %s's predecessors not consistent", b)
				}
			}
		}

	f.invalidateCFG()
	return true
}

// is this a BlockPlain with one predecessor?
func isLeafPlain(b *Block) bool {
	return b.Kind == BlockPlain && len(b.Preds) == 1
}

func clobberBlock(b *Block) {
	b.Values = nil
	b.Preds = nil
	b.Succs = nil
	b.Aux = nil
	b.ResetControls()
	b.Likely = BranchUnknown
	b.Kind = BlockInvalid
}