l.outer.children = append(l.outer.children, l)
		}
	}
	ln.initializedChildren = true
}

// calculateDepths uses the children field of loops
// to determine the nesting depth (outer=1) of each
// loop.  This is helpful for finding exit edges.
func (ln *loopnest) calculateDepths() {
	if ln.initializedDepth {
		return
	}
	ln.assembleChildren()
	for _, l := range ln.loops {
		if l.outer == nil {

	defer f.Cache.freeBlockSlice(target)

	// Grab loop information.
	// We use this to make sure we don't tighten a value into a (deeper) loop.
	idom := f.Idom()
	loops := f.loopnest()
	loops.calculateDepths()

	changed := true
	for changed {
		changed = false

		// Reset target
		for i := range target {
			target[i] = nil
		}

		// Compute target locations (for moveable values only).

	// approximate x dying with:
	//  1) target is x's only use.
	//  2) target is not in a deeper loop than x.
	if x.Uses != 1 {
		return false
	}
	loopnest := x.Block.Func.loopnest()
	loopnest.calculateDepths()
	if loopnest.depth(target.Block.ID) > loopnest.depth(x.Block.ID) {
		return false
	}
	return canMergeLoad(target, load)
}

// canMergeLoad reports whether the load can be merged into target without

	// components as single blocks, duplicated calculated liveness information
	// out to all of them.
	po := f.postorder()
	s.loopnest = f.loopnest()
	s.loopnest.calculateDepths()
	for {
		changed := false

		for _, b := range po {
			// Start with known live values at the end of the block.
			// Add len(b.Values) to adjust from end-of-block distance