&gt; I don&#x27;t understand what you mean by &quot;fully pruned programs&quot;. Maybe you want to refer to pruned SSA form.<p>The mem2reg pass in LLVM is the recommended method of constructing pruned SSA form. It just implements the standard algorithm.<p>&gt; QBE does not really &quot;alternate&quot; SSA&#x2F;non-SSA, SSA form is built once at the beginning of the compilation pipeline and preserved later.<p>The QBE IL presented to the user is not in SSA form, but internally within your compiler, an SSA representation is kept. I prefer to not have syntactic sugar in my IL.