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

src/mips64/macro-assembler-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 <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_MIPS64
 
@@ skipping 3970 matching lines @@
                               SmiCheckType smi_check_type) {
   if (smi_check_type == DO_SMI_CHECK) {
     JumpIfSmi(obj, fail);
   }
   ld(scratch, FieldMemOperand(obj, HeapObject::kMapOffset));
   LoadRoot(at, index);
   Branch(fail, ne, scratch, Operand(at));
 }
 
 
+void MacroAssembler::CmpWeakValue(Register match, Register value,
+                                  Handle<WeakCell> cell) {
+  li(match, Operand(cell));
+  ld(match, FieldMemOperand(match, WeakCell::kValueOffset));
+  Dsubu(match, value, match);
+}
+
+
+void MacroAssembler::LoadWeakValue(Register value, Handle<WeakCell> cell,
+                                   Label* miss) {
+  li(value, Operand(cell));
+  ld(value, FieldMemOperand(value, WeakCell::kValueOffset));
+  JumpIfSmi(value, miss);
+}
+
+
 void MacroAssembler::MovFromFloatResult(const DoubleRegister dst) {
   if (IsMipsSoftFloatABI) {
     Move(dst, v0, v1);
   } else {
     Move(dst, f0);  // Reg f0 is o32 ABI FP return value.
   }
 }
 
 
 void MacroAssembler::MovFromFloatParameter(const DoubleRegister dst) {
@@ skipping 2308 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_MIPS64