A64: Implement and use FillFields

src/a64/builtins-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 397 matching lines @@
       Register new_obj = x4;
       __ Ldrb(obj_size, FieldMemOperand(init_map, Map::kInstanceSizeOffset));
       __ Allocate(obj_size, new_obj, x10, x11, &rt_call, SIZE_IN_WORDS);
 
       // Allocated the JSObject, now initialize the fields. Map is set to
       // initial map and properties and elements are set to empty fixed array.
       // NB. the object pointer is not tagged, so MemOperand is used.
       Register empty = x5;
       __ LoadRoot(empty, Heap::kEmptyFixedArrayRootIndex);
       __ Str(init_map, MemOperand(new_obj, JSObject::kMapOffset));
-      __ Str(empty, MemOperand(new_obj, JSObject::kPropertiesOffset));
-      __ Str(empty, MemOperand(new_obj, JSObject::kElementsOffset));
+      STATIC_ASSERT(JSObject::kElementsOffset ==
+          (JSObject::kPropertiesOffset + kPointerSize));
+      __ Stp(empty, empty, MemOperand(new_obj, JSObject::kPropertiesOffset));
 
       Register first_prop = x5;
       __ Add(first_prop, new_obj, JSObject::kHeaderSize);
 
       // Fill all of the in-object properties with the appropriate filler.
-      Register obj_end = x6;
-      __ Add(obj_end, new_obj, Operand(obj_size, LSL, kPointerSizeLog2));
       Register undef = x7;
       __ LoadRoot(undef, Heap::kUndefinedValueRootIndex);
 
       // Obtain number of pre-allocated property fields and in-object
       // properties.
       Register prealloc_fields = x10;
       Register inobject_props = x11;
       Register inst_sizes = x11;
       __ Ldr(inst_sizes, FieldMemOperand(init_map, Map::kInstanceSizesOffset));
       __ Ubfx(prealloc_fields, inst_sizes,
               Map::kPreAllocatedPropertyFieldsByte * kBitsPerByte,
               kBitsPerByte);
       __ Ubfx(inobject_props, inst_sizes,
               Map::kInObjectPropertiesByte * kBitsPerByte, kBitsPerByte);
 
+      // Calculate number of property fields in the object.
+      Register prop_fields = x6;
+      __ Sub(prop_fields, obj_size, JSObject::kHeaderSize / kPointerSize);
+
       if (count_constructions) {
+        // Fill the pre-allocated fields with undef.
+        __ FillFields(first_prop, prealloc_fields, undef);
+
         // Register first_non_prealloc is the offset of the first field after
         // pre-allocated fields.
         Register first_non_prealloc = x12;
         __ Add(first_non_prealloc, first_prop,
                Operand(prealloc_fields, LSL, kPointerSizeLog2));
 
         if (FLAG_debug_code) {
+          Register obj_end = x5;

[ulan, 2014/03/12 12:17:26]

Maybe set first_prop = NoReg to show that it is not used anymore? The same for
prop_fields below.

+          __ Add(obj_end, new_obj, Operand(obj_size, LSL, kPointerSizeLog2));
           __ Cmp(first_non_prealloc, obj_end);
           __ Assert(le, kUnexpectedNumberOfPreAllocatedPropertyFields);
         }
-        __ InitializeFieldsWithFiller(first_prop, first_non_prealloc, undef);
-        // To allow for truncation.
-        __ LoadRoot(x12, Heap::kOnePointerFillerMapRootIndex);
-        __ InitializeFieldsWithFiller(first_prop, obj_end, x12);
+
+        // Fill the remaining fields with one pointer filler map.
+        Register one_pointer_filler = x5;
+        Register non_prealloc_fields = x6;
+        __ LoadRoot(one_pointer_filler, Heap::kOnePointerFillerMapRootIndex);
+        __ Sub(non_prealloc_fields, prop_fields, prealloc_fields);
+        __ FillFields(first_non_prealloc, non_prealloc_fields,
+                      one_pointer_filler);
       } else {
-        __ InitializeFieldsWithFiller(first_prop, obj_end, undef);
+        // Fill all of the property fields with undef.
+        __ FillFields(first_prop, prop_fields, undef);
       }
 
       // Add the object tag to make the JSObject real, so that we can continue
       // and jump into the continuation code at any time from now on. Any
       // failures need to undo the allocation, so that the heap is in a
       // consistent state and verifiable.
       __ Add(new_obj, new_obj, kHeapObjectTag);
 
       // Check if a non-empty properties array is needed. Continue with
       // allocated object if not, or fall through to runtime call if it is.
       Register element_count = x3;
       __ Ldrb(x3, FieldMemOperand(init_map, Map::kUnusedPropertyFieldsOffset));

[ulan, 2014/03/12 12:17:26]

x3 => element_count, here and below.

       // The field instance sizes contains both pre-allocated property fields
       // and in-object properties.
       __ Add(x3, x3, prealloc_fields);
       __ Subs(element_count, x3, inobject_props);
 
       // Done if no extra properties are to be allocated.
       __ B(eq, &allocated);
       __ Assert(pl, kPropertyAllocationCountFailed);
 
       // Scale the number of elements by pointer size and add the header for
       // FixedArrays to the start of the next object calculation from above.
       Register new_array = x5;
       Register array_size = x6;
       __ Add(array_size, element_count, FixedArray::kHeaderSize / kPointerSize);
       __ Allocate(array_size, new_array, x11, x12, &undo_allocation,
                   static_cast<AllocationFlags>(RESULT_CONTAINS_TOP |
                                                SIZE_IN_WORDS));
 
       Register array_map = x10;
       __ LoadRoot(array_map, Heap::kFixedArrayMapRootIndex);
       __ Str(array_map, MemOperand(new_array, FixedArray::kMapOffset));
       __ SmiTag(x0, element_count);
       __ Str(x0, MemOperand(new_array, FixedArray::kLengthOffset));
 
       // Initialize the fields to undefined.
       Register elements = x10;
-      Register elements_end  = x11;
       __ Add(elements, new_array, FixedArray::kHeaderSize);
-      __ Add(elements_end, elements,
-             Operand(element_count, LSL, kPointerSizeLog2));
-      __ InitializeFieldsWithFiller(elements, elements_end, undef);
+      __ FillFields(elements, element_count, undef);
 
       // Store the initialized FixedArray into the properties field of the
       // JSObject.
       __ Add(new_array, new_array, kHeapObjectTag);
       __ Str(new_array, FieldMemOperand(new_obj, JSObject::kPropertiesOffset));
 
       // Continue with JSObject being successfully allocated.
       __ B(&allocated);
 
       // Undo the setting of the new top so that the heap is verifiable. For
@@ skipping 972 matching lines @@
   __ Bind(&dont_adapt_arguments);
   __ Jump(code_entry);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM