func memcombine(f *Func) {
	// This optimization requires that the architecture has
	// unaligned loads and unaligned stores.
	if !f.Config.unalignedOK {
		return
	}

	memcombineLoads(f)
	memcombineStores(f)
}

func memcombineLoads(f *Func) {
	// Find "OR trees" to start with.
	mark := f.newSparseSet(f.NumValues())
	defer f.retSparseSet(mark)
	var order []*Value