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

src/mips/macro-assembler-mips.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 <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_MIPS
 
@@ skipping 4303 matching lines @@
   lw(scratch, FieldMemOperand(object, HeapObject::kMapOffset));
   lbu(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
   Branch(fail, hi, scratch, Operand(LAST_NAME_TYPE));
 }
 
 
 // ---------------------------------------------------------------------------
 // Support functions.
 
 
+void MacroAssembler::GetMapConstructor(Register result, Register map,
+                                       Register temp, Register temp2) {
+  Label done, loop;
+  lw(result, FieldMemOperand(map, Map::kConstructorOrBackPointerOffset));
+  bind(&loop);
+  JumpIfSmi(result, &done);
+  GetObjectType(result, temp, temp2);
+  Branch(&done, ne, temp2, Operand(MAP_TYPE));
+  lw(result, FieldMemOperand(result, Map::kConstructorOrBackPointerOffset));
+  Branch(&loop);
+  bind(&done);
+}
+
+
 void MacroAssembler::TryGetFunctionPrototype(Register function,
                                              Register result,
                                              Register scratch,
                                              Label* miss,
                                              bool miss_on_bound_function) {
   Label non_instance;
   if (miss_on_bound_function) {
     // Check that the receiver isn't a smi.
     JumpIfSmi(function, miss);
 
@@ skipping 32 matching lines @@
 
   // Get the prototype from the initial map.
   lw(result, FieldMemOperand(result, Map::kPrototypeOffset));
 
   if (miss_on_bound_function) {
     jmp(&done);
 
     // Non-instance prototype: Fetch prototype from constructor field
     // in initial map.
     bind(&non_instance);
-    lw(result, FieldMemOperand(result, Map::kConstructorOffset));
+    GetMapConstructor(result, result, scratch, at);
   }
 
   // All done.
   bind(&done);
 }
 
 
 void MacroAssembler::GetObjectType(Register object,
                                    Register map,
                                    Register type_reg) {
@@ skipping 1770 matching lines @@
   }
   if (mag.shift > 0) sra(result, result, mag.shift);
   srl(at, dividend, 31);
   Addu(result, result, Operand(at));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS