Implement optional turbofan UnalignedLoad and UnalignedStore operators

src/compiler/x64/instruction-selector-x64.cc

 // Copyright 2014 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 <algorithm>
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
@@ skipping 246 matching lines @@
     InstructionCode code =
         opcode | AddressingModeField::encode(addressing_mode);
     InstructionOperand value_operand =
         g.CanBeImmediate(value) ? g.UseImmediate(value) : g.UseRegister(value);
     inputs[input_count++] = value_operand;
     Emit(code, 0, static_cast<InstructionOperand*>(nullptr), input_count,
          inputs);
   }
 }
 
+// Architecture supports unaligned access, therefore VisitLoad is used instead
+void InstructionSelector::VisitUnalignedLoad(Node* node) { UNREACHABLE(); }
+
+// Architecture supports unaligned access, therefore VisitStore is used instead
+void InstructionSelector::VisitUnalignedStore(Node* node) { UNREACHABLE(); }
 
 void InstructionSelector::VisitCheckedLoad(Node* node) {
   CheckedLoadRepresentation load_rep = CheckedLoadRepresentationOf(node->op());
   X64OperandGenerator g(this);
   Node* const buffer = node->InputAt(0);
   Node* const offset = node->InputAt(1);
   Node* const length = node->InputAt(2);
   ArchOpcode opcode = kArchNop;
   switch (load_rep.representation()) {
     case MachineRepresentation::kWord8:
@@ skipping 1694 matching lines @@
              MachineOperatorBuilder::kFloat64RoundTruncate |
              MachineOperatorBuilder::kFloat32RoundTiesEven |
              MachineOperatorBuilder::kFloat64RoundTiesEven;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8