Revert remove dead hole check logic

src/crankshaft/x64/lithium-codegen-x64.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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/crankshaft/x64/lithium-codegen-x64.h"
 
 #include "src/base/bits.h"
 #include "src/builtins/builtins-constructor.h"
@@ skipping 2487 matching lines @@
     __ addp(rsp, reg);
     __ jmp(return_addr_reg);
   }
 }
 
 
 void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ movp(result, ContextOperand(context, instr->slot_index()));
+  if (instr->hydrogen()->RequiresHoleCheck()) {
+    __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
+    if (instr->hydrogen()->DeoptimizesOnHole()) {
+      DeoptimizeIf(equal, instr, DeoptimizeReason::kHole);
+    } else {
+      Label is_not_hole;
+      __ j(not_equal, &is_not_hole, Label::kNear);
+      __ LoadRoot(result, Heap::kUndefinedValueRootIndex);
+      __ bind(&is_not_hole);
+    }
+  }
 }
 
 
 void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
+
   Operand target = ContextOperand(context, instr->slot_index());
 
+  Label skip_assignment;
+  if (instr->hydrogen()->RequiresHoleCheck()) {
+    __ CompareRoot(target, Heap::kTheHoleValueRootIndex);
+    if (instr->hydrogen()->DeoptimizesOnHole()) {
+      DeoptimizeIf(equal, instr, DeoptimizeReason::kHole);
+    } else {
+      __ j(not_equal, &skip_assignment);
+    }
+  }
   __ movp(target, value);
+
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     SmiCheck check_needed =
       instr->hydrogen()->value()->type().IsHeapObject()
           ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     int offset = Context::SlotOffset(instr->slot_index());
     Register scratch = ToRegister(instr->temp());
     __ RecordWriteContextSlot(context,
                               offset,
                               value,
                               scratch,
                               kSaveFPRegs,
                               EMIT_REMEMBERED_SET,
                               check_needed);
   }
+
+  __ bind(&skip_assignment);
 }
 
 
 void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   HObjectAccess access = instr->hydrogen()->access();
   int offset = access.offset();
 
   if (access.IsExternalMemory()) {
     Register result = ToRegister(instr->result());
     if (instr->object()->IsConstantOperand()) {
@@ skipping 2868 matching lines @@
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64