Swapped transition array and descriptor array.

src/arm/macro-assembler-arm.cc

 // Copyright 2012 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 3661 matching lines @@
   vadd(temp_double_reg, input_reg, temp_double_reg);
   vcvt_u32_f64(temp_double_reg.low(), temp_double_reg);
   vmov(result_reg, temp_double_reg.low());
   bind(&done);
 }
 
 
 void MacroAssembler::LoadInstanceDescriptors(Register map,
                                              Register descriptors,
                                              Register scratch) {
-  ldr(descriptors,
-      FieldMemOperand(map, Map::kInstanceDescriptorsOrBackPointerOffset));
+  Register temp = descriptors;
+  ldr(temp, FieldMemOperand(map, Map::kTransitionsOrBackPointerOffset));
 
   Label ok, fail;
-  CheckMap(descriptors,
+  CheckMap(temp,
            scratch,
            isolate()->factory()->fixed_array_map(),
            &fail,
            DONT_DO_SMI_CHECK);
+  ldr(descriptors, FieldMemOperand(temp, TransitionArray::kDescriptorsOffset));
   jmp(&ok);
   bind(&fail);
   mov(descriptors, Operand(FACTORY->empty_descriptor_array()));
   bind(&ok);
 }
 
 
 void MacroAssembler::CheckEnumCache(Register null_value, Label* call_runtime) {
   Label next;
   // Preload a couple of values used in the loop.
   Register  empty_fixed_array_value = r6;
   LoadRoot(empty_fixed_array_value, Heap::kEmptyFixedArrayRootIndex);
   Register empty_descriptor_array_value = r7;

[Michael Starzinger, 2012/08/06 14:15:52]

Drop the "empty_descriptor_array_value".

[Toon Verwaest, 2012/08/07 08:33:04]

Done.

-  LoadRoot(empty_descriptor_array_value,
-           Heap::kEmptyDescriptorArrayRootIndex);
   mov(r1, r0);
   bind(&next);
 
   // Check that there are no elements.  Register r1 contains the
   // current JS object we've reached through the prototype chain.
   ldr(r2, FieldMemOperand(r1, JSObject::kElementsOffset));
   cmp(r2, empty_fixed_array_value);
   b(ne, call_runtime);
 
   // Check that instance descriptors are not empty so that we can
   // check for an enum cache.  Leave the map in r2 for the subsequent
   // prototype load.
   ldr(r2, FieldMemOperand(r1, HeapObject::kMapOffset));
-  ldr(r3, FieldMemOperand(r2, Map::kInstanceDescriptorsOrBackPointerOffset));
+  ldr(r3, FieldMemOperand(r2, Map::kTransitionsOrBackPointerOffset));
 
   CheckMap(r3,
            r7,
            isolate()->factory()->fixed_array_map(),
            call_runtime,
            DONT_DO_SMI_CHECK);
 
+  LoadRoot(empty_descriptor_array_value,

[Michael Starzinger, 2012/08/06 14:15:52]

Better use r7 directly here, so that it's clear that CheckMap above will destroy
it.

[Toon Verwaest, 2012/08/07 08:33:04]

Done.

+           Heap::kEmptyDescriptorArrayRootIndex);
+  ldr(r3, FieldMemOperand(r3, TransitionArray::kDescriptorsOffset));
+  cmp(r3, empty_descriptor_array_value);
+  b(eq, call_runtime);
+
   // Check that there is an enum cache in the non-empty instance
   // descriptors (r3).  This is the case if the next enumeration
   // index field does not contain a smi.
   ldr(r3, FieldMemOperand(r3, DescriptorArray::kEnumCacheOffset));
   JumpIfSmi(r3, call_runtime);
 
   // For all objects but the receiver, check that the cache is empty.
   Label check_prototype;
   cmp(r1, r0);
   b(eq, &check_prototype);
@@ skipping 68 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM