Module Regalloc_split

Splits the live ranges of registers by introducing new registers at destruction points. Destructions points are locations where all hardware registers are clobbered. This means that all registers live at such points would need to be spilled before and reloaded after.

This function inserts spills and reloads, but uses new names (hence introducing new registers) when reloading. This results in more registers but a less dense interference graph that would make register allocation slightly easier.

The algorithm is an adaptation of the one rewriting a CFG to put it in SSA form: we simply consider that new names are introduced at destruction points.