Swap bitfield3 and backpointer.

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 2996 matching lines @@
 }
 
 
 void MacroAssembler::AbortIfNotSmi(Register object) {
   STATIC_ASSERT(kSmiTag == 0);
   tst(object, Operand(kSmiTagMask));
   Assert(eq, "Operand is not smi");
 }
 
 
+void MacroAssembler::AbortIfNotFixedArray(Register object, Register scratch) {
+  Label ok, fail;
+  CheckMap(object,
+           scratch,
+           isolate()->factory()->fixed_array_map(),
+           &fail,
+           DONT_DO_SMI_CHECK);
+  jmp(&ok);
+  bind(&fail);
+  Abort("Operand is not a fixed array");
+  bind(&ok);
+}
+
+
 void MacroAssembler::AbortIfNotString(Register object) {
   STATIC_ASSERT(kSmiTag == 0);
   tst(object, Operand(kSmiTagMask));
   Assert(ne, "Operand is not a string");
   push(object);
   ldr(object, FieldMemOperand(object, HeapObject::kMapOffset));
   CompareInstanceType(object, object, FIRST_NONSTRING_TYPE);
   pop(object);
   Assert(lo, "Operand is not a string");
 }
@@ skipping 639 matching lines @@
   bind(&in_bounds);
   Vmov(temp_double_reg, 0.5);
   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 descriptors,
+                                             Register scratch) {
   ldr(descriptors,
-      FieldMemOperand(map, Map::kInstanceDescriptorsOrBitField3Offset));
-  Label not_smi;
-  JumpIfNotSmi(descriptors, &not_smi);
+      FieldMemOperand(map, Map::kInstanceDescriptorsOrBackPointerOffset));
+
+  Label ok, fail;
+  CheckMap(descriptors,
+           scratch,
+           isolate()->factory()->fixed_array_map(),
+           &fail,
+           DONT_DO_SMI_CHECK);
+  jmp(&ok);
+  bind(&fail);
   mov(descriptors, Operand(FACTORY->empty_descriptor_array()));
-  bind(&not_smi);
+  bind(&ok);
+
+  if (emit_debug_code()) {
+    AbortIfNotFixedArray(descriptors, scratch);
+  }
 }
 
 
 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;
   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::kInstanceDescriptorsOrBitField3Offset));
-  JumpIfSmi(r3, call_runtime);
+  ldr(r3, FieldMemOperand(r2, Map::kInstanceDescriptorsOrBackPointerOffset));
+
+  CheckMap(r3,
+           r7,
+           isolate()->factory()->fixed_array_map(),
+           call_runtime,
+           DONT_DO_SMI_CHECK);
+
+  if (emit_debug_code()) {
+    AbortIfNotFixedArray(r3, r7);
+  }
 
   // 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::kEnumerationIndexOffset));
   JumpIfSmi(r3, call_runtime);
 
   // For all objects but the receiver, check that the cache is empty.
   Label check_prototype;
   cmp(r1, r0);
@@ skipping 69 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