MIPS: Sharing of descriptor arrays.

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index 7ded49499957b010b996229de161b0268dd45192..fe703daa19331c2f5db02456125c6ff9893efd73 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -5299,20 +5299,37 @@ void MacroAssembler::LoadInstanceDescriptors(Register map,
   Register temp = descriptors;
   lw(temp, FieldMemOperand(map, Map::kTransitionsOrBackPointerOffset));
 
-  Label ok, fail;
+  Label ok, fail, load_from_back_pointer;
   CheckMap(temp,
            scratch,
            isolate()->factory()->fixed_array_map(),
            &fail,
            DONT_DO_SMI_CHECK);
-  lw(descriptors, FieldMemOperand(temp, TransitionArray::kDescriptorsOffset));
+  lw(temp, FieldMemOperand(temp, TransitionArray::kDescriptorsPointerOffset));
+  lw(descriptors, FieldMemOperand(temp, JSGlobalPropertyCell::kValueOffset));
   jmp(&ok);
+
   bind(&fail);
+  LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
+  Branch(&load_from_back_pointer, ne, temp, Operand(scratch));
   LoadRoot(descriptors, Heap::kEmptyDescriptorArrayRootIndex);
+  jmp(&ok);
+
+  bind(&load_from_back_pointer);
+  lw(temp, FieldMemOperand(temp, Map::kTransitionsOrBackPointerOffset));
+  lw(temp, FieldMemOperand(temp, TransitionArray::kDescriptorsPointerOffset));
+  lw(descriptors, FieldMemOperand(temp, JSGlobalPropertyCell::kValueOffset));
+
   bind(&ok);
 }
 
 
+void MacroAssembler::NumberOfOwnDescriptors(Register dst, Register map) {
+  lw(dst, FieldMemOperand(map, Map::kBitField3Offset));
+  DecodeField<Map::NumberOfOwnDescriptorsBits>(dst);
+}
+
+
 void MacroAssembler::EnumLength(Register dst, Register map) {
   STATIC_ASSERT(Map::EnumLengthBits::kShift == 0);
   lw(dst, FieldMemOperand(map, Map::kBitField3Offset));