Reland parts of 'Use weak cells in map checks in polymorphic ICs'

src/mips64/macro-assembler-mips64.h

 // 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.
 
 #ifndef V8_MIPS_MACRO_ASSEMBLER_MIPS_H_
 #define V8_MIPS_MACRO_ASSEMBLER_MIPS_H_
 
 #include "src/assembler.h"
 #include "src/globals.h"
 #include "src/mips64/assembler-mips64.h"
@@ skipping 1103 matching lines @@
 
   // Check if the map of an object is equal to a specified map and branch to a
   // specified target if equal. Skip the smi check if not required (object is
   // known to be a heap object)
   void DispatchMap(Register obj,
                    Register scratch,
                    Handle<Map> map,
                    Handle<Code> success,
                    SmiCheckType smi_check_type);
 
+  // Compare the given value and the value of the weak cell. Write the result
+  // to the match register.
+  void CmpWeakValue(Register match, Register value, Handle<WeakCell> cell);
+
+  // Load the value of the weak cell in the value register. Branch to the
+  // given miss label is the weak cell was cleared.
+  void LoadWeakValue(Register value, Handle<WeakCell> cell, Label* miss);
 
   // Load and check the instance type of an object for being a string.
   // Loads the type into the second argument register.
   // Returns a condition that will be enabled if the object was a string.
   Condition IsObjectStringType(Register obj,
                                Register type,
                                Register result) {
     ld(type, FieldMemOperand(obj, HeapObject::kMapOffset));
     lbu(type, FieldMemOperand(type, Map::kInstanceTypeOffset));
     And(type, type, Operand(kIsNotStringMask));
@@ skipping 653 matching lines @@
 #define CODE_COVERAGE_TOSTRING(x) CODE_COVERAGE_STRINGIFY(x)
 #define __FILE_LINE__ __FILE__ ":" CODE_COVERAGE_TOSTRING(__LINE__)
 #define ACCESS_MASM(masm) masm->stop(__FILE_LINE__); masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_MIPS_MACRO_ASSEMBLER_MIPS_H_