MIPS: Move Maps' back pointers from "transitions" to "constructor" field

src/mips64/full-codegen-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_MIPS64
 
 // Note on Mips implementation:
 //
@@ skipping 3740 matching lines @@
                 FIRST_SPEC_OBJECT_TYPE + 1);
   __ Branch(&function, eq, a1, Operand(FIRST_SPEC_OBJECT_TYPE));
 
   STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE ==
                 LAST_SPEC_OBJECT_TYPE - 1);
   __ Branch(&function, eq, a1, Operand(LAST_SPEC_OBJECT_TYPE));
   // Assume that there is no larger type.
   STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE == LAST_TYPE - 1);
 
   // Check if the constructor in the map is a JS function.
-  __ ld(v0, FieldMemOperand(v0, Map::kConstructorOffset));
-  __ GetObjectType(v0, a1, a1);
-  __ Branch(&non_function_constructor, ne, a1, Operand(JS_FUNCTION_TYPE));
+  Register instance_type = a2;
+  __ GetMapConstructor(v0, v0, a1, instance_type);
+  __ Branch(&non_function_constructor, ne, instance_type,
+            Operand(JS_FUNCTION_TYPE));
 
   // v0 now contains the constructor function. Grab the
   // instance class name from there.
   __ ld(v0, FieldMemOperand(v0, JSFunction::kSharedFunctionInfoOffset));
   __ ld(v0, FieldMemOperand(v0, SharedFunctionInfo::kInstanceClassNameOffset));
   __ Branch(&done);
 
   // Functions have class 'Function'.
   __ bind(&function);
   __ LoadRoot(v0, Heap::kFunction_stringRootIndex);
@@ skipping 1675 matching lines @@
       Assembler::target_address_at(pc_immediate_load_address)) ==
          reinterpret_cast<uint64_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS64