To add just a bit more:<p>When assignments to variables happen in the context of a procedure call it&#x27;s preferable to use registers for performance reasons since memory access (even cache) is much slower by comparison. Unfortunately registers are a limited resource, so we would like to reuse them when a variable, though in scope, isn&#x27;t &quot;live&quot; or in use.<p>This whole area of optimization is called register allocation and the optimal solution reduces to the graph coloring problem which is NP-complete. As a result there are a myriad of approximation algorithms with knobs to turn to spend a bit more complexity for a bit more accuracy. This patch appears to be the turning of one such knob.