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

src/mips64/lithium-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"
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/cpu-profiler.h"
 #include "src/hydrogen-osr.h"
@@ skipping 2600 matching lines @@
     // Faster code path to avoid two compares: subtract lower bound from the
     // actual type and do a signed compare with the width of the type range.
     __ GetObjectType(input, temp, temp2);
     __ Dsubu(temp2, temp2, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
     __ Branch(is_false, gt, temp2, Operand(LAST_NONCALLABLE_SPEC_OBJECT_TYPE -
                                            FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
   }
 
   // Now we are in the FIRST-LAST_NONCALLABLE_SPEC_OBJECT_TYPE range.
   // Check if the constructor in the map is a function.
-  __ ld(temp, FieldMemOperand(temp, Map::kConstructorOffset));
+  Register instance_type = scratch1();
+  DCHECK(!instance_type.is(temp));
+  DCHECK(!instance_type.is(temp2));
+  __ GetMapConstructor(temp, temp, temp2, instance_type);
 
   // Objects with a non-function constructor have class 'Object'.
-  __ GetObjectType(temp, temp2, temp2);
   if (String::Equals(class_name, isolate()->factory()->Object_string())) {
-    __ Branch(is_true, ne, temp2, Operand(JS_FUNCTION_TYPE));
+    __ Branch(is_true, ne, instance_type, Operand(JS_FUNCTION_TYPE));
   } else {
-    __ Branch(is_false, ne, temp2, Operand(JS_FUNCTION_TYPE));
+    __ Branch(is_false, ne, instance_type, Operand(JS_FUNCTION_TYPE));
   }
 
   // temp now contains the constructor function. Grab the
   // instance class name from there.
   __ ld(temp, FieldMemOperand(temp, JSFunction::kSharedFunctionInfoOffset));
   __ ld(temp, FieldMemOperand(temp,
                                SharedFunctionInfo::kInstanceClassNameOffset));
   // The class name we are testing against is internalized since it's a literal.
   // The name in the constructor is internalized because of the way the context
   // is booted.  This routine isn't expected to work for random API-created
@@ skipping 3412 matching lines @@
   __ li(at, scope_info);
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal