Also, QBE does not really "alternate" SSA/non-SSA, SSA form is built once at the beginning of the compilation pipeline and preserved later.
I don't understand what you mean by "fully pruned programs". Maybe you want to refer to pruned SSA form. And then, here is my point: with LLVM, either you build SSA yourself or you use allocas. QBE offers a convenient third option.
Also, QBE does not really "alternate" SSA/non-SSA, SSA form is built once at the beginning of the compilation pipeline and preserved later.
I don't understand what you mean by "fully pruned programs". Maybe you want to refer to pruned SSA form. And then, here is my point: with LLVM, either you build SSA yourself or you use allocas. QBE offers a convenient third option.