将循环中的块遍历从逆后序修改为拓扑序

src/passes/Mem2Reg.cpp

@@ -120,6 +120,7 @@ void Mem2Reg::rename(BasicBlock *bb, const Dominators *dominators_) {
             if (inst->is_phi()) {
                 auto phi = dynamic_cast<PhiInst *>(inst);
                 auto lval = phi_map_[phi];
+                if(not lval) continue;
                 if (var_stack_.find(lval) == var_stack_.end())
                     continue;
                 // assert(!var_stack_[lval].empty());