Revert of [Atomics] Remove Atomics code stubs; use TF ops

src/compiler/arm64/instruction-selector-arm64.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 "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 2228 matching lines @@
     Node* right_of_left = left->InputAt(1);
     Emit(kArm64Bfi, g.DefineSameAsFirst(left), g.UseRegister(right_of_left),
          g.UseRegister(right), g.TempImmediate(32), g.TempImmediate(32));
     Emit(kArm64Float64MoveU64, g.DefineAsRegister(node), g.UseRegister(left));
     return;
   }
   Emit(kArm64Float64InsertHighWord32, g.DefineAsRegister(node),
        g.UseRegister(left), g.UseRegister(right));
 }
 
-void InstructionSelector::VisitAtomicLoad(Node* node) {
-  LoadRepresentation load_rep = LoadRepresentationOf(node->op());
-  Arm64OperandGenerator g(this);
-  Node* base = node->InputAt(0);
-  Node* index = node->InputAt(1);
-  ArchOpcode opcode = kArchNop;
-  ImmediateMode immediate_mode = kNoImmediate;
-  switch (load_rep.representation()) {
-    case MachineRepresentation::kWord8:
-      opcode = load_rep.IsSigned() ? kAtomicLoadInt8 : kAtomicLoadUint8;
-      immediate_mode = kLoadStoreImm8;
-      break;
-    case MachineRepresentation::kWord16:
-      opcode = load_rep.IsSigned() ? kAtomicLoadInt16 : kAtomicLoadUint16;
-      immediate_mode = kLoadStoreImm16;
-      break;
-    case MachineRepresentation::kWord32:
-      opcode = kAtomicLoadWord32;
-      immediate_mode = kLoadStoreImm32;
-      break;
-    default:
-      UNREACHABLE();
-      return;
-  }
-  Emit(opcode | AddressingModeField::encode(kMode_MRR),
-       g.DefineAsRegister(node), g.UseRegister(base), g.UseRegister(index));
-}
 
 // static
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {
   return MachineOperatorBuilder::kFloat32Max |
          MachineOperatorBuilder::kFloat32Min |
          MachineOperatorBuilder::kFloat32RoundDown |
          MachineOperatorBuilder::kFloat64Max |
          MachineOperatorBuilder::kFloat64Min |
          MachineOperatorBuilder::kFloat64RoundDown |
          MachineOperatorBuilder::kFloat32RoundUp |
          MachineOperatorBuilder::kFloat64RoundUp |
          MachineOperatorBuilder::kFloat32RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesAway |
          MachineOperatorBuilder::kFloat32RoundTiesEven |
          MachineOperatorBuilder::kFloat64RoundTiesEven |
          MachineOperatorBuilder::kWord32ShiftIsSafe |
          MachineOperatorBuilder::kInt32DivIsSafe |
          MachineOperatorBuilder::kUint32DivIsSafe |
          MachineOperatorBuilder::kWord32ReverseBits |
          MachineOperatorBuilder::kWord64ReverseBits;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8