src/share/vm/opto/library_call.cpp

*** 4498,4527 ****
      // (6) length must not be negative.
      if (!length_never_negative) {
        generate_negative_guard(copy_length, slow_region);
      }
  
      if (!stopped() && must_clear_dest) {
        Node* dest_length = alloc->in(AllocateNode::ALength);
        if (_gvn.eqv_uncast(copy_length, dest_length)
            || _gvn.find_int_con(dest_length, 1) <= 0) {
!         // There is no zeroing to do.
        } else {
          // Clear the whole thing since there are no source elements to copy.
          generate_clear_array(adr_type, dest, basic_elem_type,
                               intcon(0), NULL,
                               alloc->in(AllocateNode::AllocSize));
-       }
-     }
- 
      // Use a secondary InitializeNode as raw memory barrier.
      // Currently it is needed only on this path since other
      // paths have stub or runtime calls as raw memory barriers.
      InitializeNode* init = insert_mem_bar_volatile(Op_Initialize,
                                                     Compile::AliasIdxRaw,
                                                     top())->as_Initialize();
      init->set_complete(&_gvn);  // (there is no corresponding AllocateNode)
  
      // Present the results of the fast call.
      result_region->init_req(zero_path, control());
      result_i_o   ->init_req(zero_path, i_o());
      result_memory->init_req(zero_path, memory(adr_type));
--- 4498,4527 ----
      // (6) length must not be negative.
      if (!length_never_negative) {
        generate_negative_guard(copy_length, slow_region);
      }
  
+     // copy_length is 0.
      if (!stopped() && must_clear_dest) {
        Node* dest_length = alloc->in(AllocateNode::ALength);
        if (_gvn.eqv_uncast(copy_length, dest_length)
            || _gvn.find_int_con(dest_length, 1) <= 0) {
!         // There is no zeroing to do. No need for a secondary raw memory barrier.
        } else {
          // Clear the whole thing since there are no source elements to copy.
          generate_clear_array(adr_type, dest, basic_elem_type,
                               intcon(0), NULL,
                               alloc->in(AllocateNode::AllocSize));
          // Use a secondary InitializeNode as raw memory barrier.
          // Currently it is needed only on this path since other
          // paths have stub or runtime calls as raw memory barriers.
          InitializeNode* init = insert_mem_bar_volatile(Op_Initialize,
                                                         Compile::AliasIdxRaw,
                                                         top())->as_Initialize();
          init->set_complete(&_gvn);  // (there is no corresponding AllocateNode)
+       }
+     }
  
      // Present the results of the fast call.
      result_region->init_req(zero_path, control());
      result_i_o   ->init_req(zero_path, i_o());
      result_memory->init_req(zero_path, memory(adr_type));