src/hotspot/share/c1/c1_LIRGenerator.cpp

@@ -1985,11 +1985,12 @@
     length.set_instruction(x->length());
     length.load_item();
   }
 
   array.load_item();
-  if (index.is_constant() && can_inline_as_constant(x->index())) {
+  if (index.is_constant() && can_inline_as_constant(x->index())
+      && !x->array()->maybe_flattened_array()) {
     // let it be a constant
     index.dont_load_item();
   } else {
     index.load_item();
   }

@@ -2023,30 +2024,43 @@
       // The range check performs the null check, so clear it out for the load
       null_check_info = NULL;
     }
   }
 
-  if (x->array()->is_flattened_array()) {
-    if (x->array()->declared_type()->is_loaded()) {
+  if (x->array()->is_loaded_flattened_array()) {
       // Find the destination address (of the NewValueTypeInstance)
       LIR_Opr obj = x->vt()->operand();
       LIRItem obj_item(x->vt(), this);
 
       access_flattened_array(true, array, index, obj_item);
       set_no_result(x);
-      return;
     } else {
-      // If the array is indeed flattened, deopt. Otherwise access it as a normal object array.
-      CodeEmitInfo* deopt_info = state_for(x, x->state_before());
-      maybe_deopt_value_array_access(array, null_check_info, deopt_info);
-    }
+    LIR_Opr result = rlock_result(x, x->elt_type());
+    LoadFlattenedArrayStub* slow_path = NULL;
+    
+    if (x->array()->maybe_flattened_array()) {
+      // Check if we indeed have a flattened array
+      slow_path = new LoadFlattenedArrayStub(array.result(), index.result(), result, state_for(x));
+      LIR_Opr array_klass_reg = new_register(T_METADATA);
+
+      __ move(new LIR_Address(array.result(), oopDesc::klass_offset_in_bytes(), T_ADDRESS), array_klass_reg);
+      LIR_Opr layout = new_register(T_INT);
+      __ move(new LIR_Address(array_klass_reg, in_bytes(Klass::layout_helper_offset()), T_INT), layout);
+      __ shift_right(layout, Klass::_lh_array_tag_shift, layout);
+      __ cmp(lir_cond_equal, layout, LIR_OprFact::intConst(Klass::_lh_array_tag_vt_value));
+      __ branch(lir_cond_equal, T_ILLEGAL, slow_path);
   }
+
   DecoratorSet decorators = IN_HEAP | IS_ARRAY;
-  LIR_Opr result = rlock_result(x, x->elt_type());
   access_load_at(decorators, x->elt_type(),
                  array, index.result(), result,
                  NULL, null_check_info);
+
+    if (slow_path != NULL) {
+      __ branch_destination(slow_path->continuation());
+    }
+  }
 }
 
 
 void LIRGenerator::do_NullCheck(NullCheck* x) {
   if (x->can_trap()) {