682 }
683 
684 bool ArrayCopyNode::may_modify_helper(const TypeOopPtr* t_oop, Node* n, PhaseValues* phase, ArrayCopyNode*& ac) {
685   if (n != nullptr &&
686       n->is_ArrayCopy() &&
687       n->as_ArrayCopy()->may_modify(t_oop, phase)) {
688     ac = n->as_ArrayCopy();
689     return true;
690   }
691   return false;
692 }
693 
694 bool ArrayCopyNode::may_modify(const TypeOopPtr* t_oop, MemBarNode* mb, PhaseValues* phase, ArrayCopyNode*& ac) {
695   if (mb->trailing_expanded_array_copy()) {
696     return true;
697   }
698 
699   Node* c = mb->in(0);
700 
701   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
702   // step over g1 gc barrier if we're at e.g. a clone with ReduceInitialCardMarks off
703   c = bs->step_over_gc_barrier(c);
704 
705   CallNode* call = nullptr;
706   guarantee(c != nullptr, "step_over_gc_barrier failed, there must be something to step to.");
707   if (c->is_Region()) {
708     for (uint i = 1; i < c->req(); i++) {
709       if (c->in(i) != nullptr) {
710         Node* n = c->in(i)->in(0);
711         if (may_modify_helper(t_oop, n, phase, ac)) {
712           assert(c == mb->in(0), "only for clone");
713           return true;
714         }
715       }
716     }
717   } else if (may_modify_helper(t_oop, c->in(0), phase, ac)) {
718 #ifdef ASSERT
719     bool use_ReduceInitialCardMarks = BarrierSet::barrier_set()->is_a(BarrierSet::CardTableBarrierSet) &&
720       static_cast<CardTableBarrierSetC2*>(bs)->use_ReduceInitialCardMarks();
721     assert(c == mb->in(0) || (ac->is_clonebasic() && !use_ReduceInitialCardMarks), "only for clone");
722 #endif
723     return true;

682 }
683 
684 bool ArrayCopyNode::may_modify_helper(const TypeOopPtr* t_oop, Node* n, PhaseValues* phase, ArrayCopyNode*& ac) {
685   if (n != nullptr &&
686       n->is_ArrayCopy() &&
687       n->as_ArrayCopy()->may_modify(t_oop, phase)) {
688     ac = n->as_ArrayCopy();
689     return true;
690   }
691   return false;
692 }
693 
694 bool ArrayCopyNode::may_modify(const TypeOopPtr* t_oop, MemBarNode* mb, PhaseValues* phase, ArrayCopyNode*& ac) {
695   if (mb->trailing_expanded_array_copy()) {
696     return true;
697   }
698 
699   Node* c = mb->in(0);
700 
701   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();


702 
703   CallNode* call = nullptr;
704   guarantee(c != nullptr, "step_over_gc_barrier failed, there must be something to step to.");
705   if (c->is_Region()) {
706     for (uint i = 1; i < c->req(); i++) {
707       if (c->in(i) != nullptr) {
708         Node* n = c->in(i)->in(0);
709         if (may_modify_helper(t_oop, n, phase, ac)) {
710           assert(c == mb->in(0), "only for clone");
711           return true;
712         }
713       }
714     }
715   } else if (may_modify_helper(t_oop, c->in(0), phase, ac)) {
716 #ifdef ASSERT
717     bool use_ReduceInitialCardMarks = BarrierSet::barrier_set()->is_a(BarrierSet::CardTableBarrierSet) &&
718       static_cast<CardTableBarrierSetC2*>(bs)->use_ReduceInitialCardMarks();
719     assert(c == mb->in(0) || (ac->is_clonebasic() && !use_ReduceInitialCardMarks), "only for clone");
720 #endif
721     return true;