phielim(f)

	// loop of copyelimValue(v) process has been done in phielim() pass.
	// Update block control values.
	for _, b := range f.Blocks {
		for i, v := range b.ControlValues() {
			if v.Op == OpCopy {
				b.ReplaceControl(i, v.Args[0])
			}
		}
	}

	// Update named values.
	for _, name := range f.Names {
		values := f.NamedValues[*name]
		for i, v := range values {
			if v.Op == OpCopy {
				values[i] = v.Args[0]

				flag = v
			}
		}
		for i, v := range b.ControlValues() {
			if v != flag && v.Type.IsFlags() {
				// Recalculate control value.
				remove = append(remove, v)
				c := copyFlags(v, b)
				b.ReplaceControl(i, c)
				flag = v
			}
		}
		if v := end[b.ID]; v != nil && v != flag {
			// Need to reissue flag generator for use by
			// subsequent blocks.
			remove = append(remove, v)
			copyFlags(v, b)

			if x := rewrite[v.ID]; x != nil {
				if v.Op == OpNilCheck {
					// nilcheck pass will remove the nil checks and log
					// them appropriately, so don't mess with them here.
					continue
				}
				b.ReplaceControl(i, x)
			}
		}
	}

	if f.pass.stats > 0 {
		f.LogStat("CSE REWRITES", rewrites)
	}
}

// An eqclass approximates an equivalence class. During the