src/share/vm/opto/library_call.cpp

*** 2644,2657 ****
    // so there's no problems making a strong assert about mixing users
    // of safe & unsafe memory.
    if (need_mem_bar) insert_mem_bar(Op_MemBarCPUOrder);
  
    if (!is_store) {
      MemNode::MemOrd mo = is_volatile ? MemNode::acquire : MemNode::unordered;
      // To be valid, unsafe loads may depend on other conditions than
      // the one that guards them: pin the Load node
!     Node* p = make_load(control(), adr, value_type, type, adr_type, mo, LoadNode::Pinned, is_volatile);
      // load value
      switch (type) {
      case T_BOOLEAN:
      case T_CHAR:
      case T_BYTE:
--- 2644,2669 ----
    // so there's no problems making a strong assert about mixing users
    // of safe & unsafe memory.
    if (need_mem_bar) insert_mem_bar(Op_MemBarCPUOrder);
  
     if (!is_store) {
+     Node* p = NULL;
+     // Try to constant fold a load from a constant field
+     ciField* field = alias_type->field();
+     if (heap_base_oop != top() &&
+         field != NULL && field->is_constant() && field->layout_type() == type) {
+       // final or stable field
+       const Type* con_type = Type::make_constant(alias_type->field(), heap_base_oop);
+       if (con_type != NULL) {
+         p = makecon(con_type);
+       }
+     }
+     if (p == NULL) {
        MemNode::MemOrd mo = is_volatile ? MemNode::acquire : MemNode::unordered;
        // To be valid, unsafe loads may depend on other conditions than
        // the one that guards them: pin the Load node
!       p = make_load(control(), adr, value_type, type, adr_type, mo, LoadNode::Pinned, is_volatile);
        // load value
        switch (type) {
        case T_BOOLEAN:
        case T_CHAR:
        case T_BYTE:
*** 2673,2682 ****
--- 2685,2695 ----
          break;
        default:
          fatal(err_msg_res("unexpected type %d: %s", type, type2name(type)));
          break;
        }
+     }
      // The load node has the control of the preceding MemBarCPUOrder.  All
      // following nodes will have the control of the MemBarCPUOrder inserted at
      // the end of this method.  So, pushing the load onto the stack at a later
      // point is fine.
      set_result(p);