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

src/arm64/macro-assembler-arm64.cc

 // Copyright 2013 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_ARM64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
@@ skipping 3787 matching lines @@
     JumpIfSmi(obj, &fail);
   }
   Ldr(scratch, FieldMemOperand(obj, HeapObject::kMapOffset));
   Cmp(scratch, Operand(map));
   B(ne, &fail);
   Jump(success, RelocInfo::CODE_TARGET);
   Bind(&fail);
 }
 
 
+void MacroAssembler::CmpWeakValue(Register value, Handle<WeakCell> cell,
+                                  Register scratch) {
+  Mov(scratch, Operand(cell));
+  Ldr(scratch, FieldMemOperand(scratch, WeakCell::kValueOffset));
+  Cmp(value, scratch);
+}
+
+
+void MacroAssembler::LoadWeakValue(Register value, Handle<WeakCell> cell,
+                                   Label* miss) {
+  Mov(value, Operand(cell));
+  Ldr(value, FieldMemOperand(value, WeakCell::kValueOffset));
+  JumpIfSmi(value, miss);
+}
+
+
 void MacroAssembler::TestMapBitfield(Register object, uint64_t mask) {
   UseScratchRegisterScope temps(this);
   Register temp = temps.AcquireX();
   Ldr(temp, FieldMemOperand(object, HeapObject::kMapOffset));
   Ldrb(temp, FieldMemOperand(temp, Map::kBitFieldOffset));
   Tst(temp, mask);
 }
 
 
 void MacroAssembler::LoadElementsKindFromMap(Register result, Register map) {
@@ skipping 1571 matching lines @@
   }
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64