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
		for _, e := range b.Preds {
			if e.b.Kind != BlockPlain {
				continue
			}
			if loopnest.b2l[e.b.ID] != loop {
				continue
			}
			p = e.b
		}
		if p == nil {
			continue
		}
		p.Hotness |= HotInitial

	for len(q) > 0 {
		// pop a reachable value
		v := q[len(q)-1]
		q[len(q)-1] = nil
		q = q[:len(q)-1]
		for i, x := range v.Args {
			if v.Op == OpPhi && !reachable[v.Block.Preds[i].b.ID] {
				continue
			}
			if !live[x.ID] {
				live[x.ID] = true
				q = append(q, x) // push
				if x.Pos.IsStmt() != src.PosNotStmt {
					liveOrderStmts = append(liveOrderStmts, x)
				}
			}

					if opcodeTable[v.Op].commutative {
						desired.addList(v.Args[1].ID, prefs)
					}
					desired.addList(v.Args[0].ID, prefs)
				}
			}

			// For each predecessor of b, expand its list of live-at-end values.
			// invariant: live contains the values live at the start of b (excluding phi inputs)
			for i, e := range b.Preds {
				p := e.b
				// Compute additional distance for the edge.

		node := work[len(work)-1]
		work = work[:len(work)-1]

		switch node.op {
		case Work:
			b := node.block

			// First, see if we're dominated by an explicit nil check.
			if len(b.Preds) == 1 {
				p := b.Preds[0].b
				if p.Kind == BlockIf && p.Controls[0].Op == OpIsNonNil && p.Succs[0].b == b {
					if ptr := p.Controls[0].Args[0]; nonNilValues[ptr.ID] == nil {
						nonNilValues[ptr.ID] = ptr

//		do something
//	      nxt = inc + ind
//		goto loop
//
//	 exit_loop:
func findIndVar(f *Func) []indVar {
	var iv []indVar
	sdom := f.Sdom()

	for _, b := range f.Blocks {
		if b.Kind != BlockIf || len(b.Preds) != 2 {
			continue
		}

		var ind *Value   // induction variable
		var init *Value  // starting value
		var limit *Value // ending value

		// Check that the control if it either ind </<= limit or limit </<= ind.

// CHECK: ^bb1([[CONDARG0:%.+]]: tensor<!tf_type.variant>):        // 2 preds: ^bb0, ^bb2
// CHECK:   [[CONTINUE:%.+]] = call @testWhileCond([[CONDARG0]]) : (tensor<!tf_type.variant>) -> tensor<i1>
// CHECK:   [[TOBOOL:%.+]] = "tf.ToBool"([[CONTINUE]]) : (tensor<i1>) -> tensor<i1>
// CHECK:   [[PRED:%.+]] = tensor.extract [[TOBOOL]][] : tensor<i1>

					}
				}
			}

			// for each predecessor of b, expand its list of live-at-end values
			// invariant: s contains the values live at the start of b (excluding phi inputs)
			for i, e := range b.Preds {
				p := e.b
				t.clear()
				t.addAll(s.live[p.ID])
				t.addAll(live.contents())
				t.addAll(spillLive[p.ID])
				for _, v := range phis {
					a := v.Args[i]
					if s.values[a.ID].needSlot {

	}
	fmt.Fprintf(p.w, "<ul class=\"%s ssa-print-func %s\">", b, dead)
	fmt.Fprintf(p.w, "<li class=\"ssa-start-block\">%s:", b.HTML())
	if len(b.Preds) > 0 {
		io.WriteString(p.w, " &#8592;") // left arrow
		for _, e := range b.Preds {
			pred := e.b
			fmt.Fprintf(p.w, " %s", pred.HTML())
		}
	}
	if len(b.Values) > 0 {
		io.WriteString(p.w, `<button onclick="hideBlock(this)">-</button>`)
	}

	// Max distance
	d := 100

	for d > 0 {
		for _, x := range a {
			if b == x.Block {
				goto found
			}
		}
		if len(b.Preds) > 1 {
			// Don't know which way to go back. Abort.
			return nil
		}
		b = b.Preds[0].b
		d--
	}
	return nil // too far away
found:
	// At this point, r is the first value in a that we find by walking backwards.

		bEnd.Pos = b.Pos
		b.Pos = pos

		// Set up control flow for end block.
		bEnd.CopyControls(b)
		bEnd.Likely = b.Likely
		for _, e := range b.Succs {
			bEnd.Succs = append(bEnd.Succs, e)
			e.b.Preds[e.i].b = bEnd
		}

		// set up control flow for write barrier test
		// load word, test word, avoiding partial register write from load byte.
		cfgtypes := &f.Config.Types