// AddEdgeTo adds an edge from block b to block c.
func (b *Block) AddEdgeTo(c *Block) {
	i := len(b.Succs)
	j := len(c.Preds)
	b.Succs = append(b.Succs, Edge{c, j})
	c.Preds = append(c.Preds, Edge{b, i})
	b.Func.invalidateCFG()
}

// removePred removes the ith input edge from b.
// It is the responsibility of the caller to remove
// the corresponding successor edge, and adjust any
// phi values by calling b.removePhiArg(v, i).

		m := len(s.Values)
		for i := 0; i < k; i++ {
			s.Values = append(s.Values, nil)
		}
		copy(s.Values[k:], s.Values[:m])
		copy(s.Values, b.Values)
	}
	if n < len(f.Blocks) {
		f.invalidateCFG()
		tail := f.Blocks[n:]
		for i := range tail {
			tail[i] = nil
		}
		f.Blocks = f.Blocks[:n]
	}
}

// emptyBlock reports whether the block does not contain actual
// instructions.

		}
	}

	dom.Values = append(dom.Values, simple.Values...)
	dom.Values = append(dom.Values, post.Values...)

	// Trash 'post' and 'simple'
	clobberBlock(post)
	clobberBlock(simple)

	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) {

func (f *Func) loopnest() *loopnest {
	if f.cachedLoopnest == nil {
		f.cachedLoopnest = loopnestfor(f)
	}
	return f.cachedLoopnest
}

// invalidateCFG tells f that its CFG has changed.
func (f *Func) invalidateCFG() {
	f.cachedPostorder = nil
	f.cachedIdom = nil
	f.cachedSdom = nil
	f.cachedLoopnest = nil
}

// DebugHashMatch returns
//

			if typ&fuseTypeShortCircuit != 0 {
				changed = shortcircuitBlock(b) || changed
			}
		}

		if typ&fuseTypeBranchRedirect != 0 {
			changed = fuseBranchRedirect(f) || changed
		}
		if changed {
			f.invalidateCFG()
		}
	}
}

// fuseBlockIf handles the following cases where s0 and s1 are empty blocks.
//
//	   b        b           b       b
//	\ / \ /    | \  /    \ / |     | |
//	 s0  s1    |  s1      s0 |     | |

		// backedge at index i.
		for _, v := range h.Values {
			if v.Op == OpPhi && v != headerMemPhi {
				v.AddArg(v.Args[i])
			}
		}
	}

	f.invalidateCFG()

	if f.pass.debug > 1 {
		sdom = newSparseTree(f, f.Idom())
		fmt.Printf("after %s = %s\n", f.Name, sdom.treestructure(f.Entry))
	}
}

// newPhiFor inserts a new Phi function into b,