[Atomics] Remove Atomics code stubs; use TF ops

src/compiler/instruction-scheduler.cc

 // Copyright 2015 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-scheduler.h"
 
 #include "src/base/adapters.h"
 #include "src/base/utils/random-number-generator.h"
 
 namespace v8 {
@@ skipping 236 matching lines @@
 
     case kCheckedStoreWord8:
     case kCheckedStoreWord16:
     case kCheckedStoreWord32:
     case kCheckedStoreWord64:
     case kCheckedStoreFloat32:
     case kCheckedStoreFloat64:
     case kArchStoreWithWriteBarrier:
       return kHasSideEffect;
 
+    case kAtomicLoadInt8:
+    case kAtomicLoadUint8:
+    case kAtomicLoadInt16:
+    case kAtomicLoadUint16:
+    case kAtomicLoadWord32:
+      return kIsLoadOperation;
+
 #define CASE(Name) case k##Name:
     TARGET_ARCH_OPCODE_LIST(CASE)
 #undef CASE
       return GetTargetInstructionFlags(instr);
   }
 
   UNREACHABLE();
   return kNoOpcodeFlags;
 }
 
@@ skipping 42 matching lines @@
       }
     }
 
     node->set_total_latency(max_latency + node->latency());
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8