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

src/compiler/machine-operator.h

 // 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.
 
 #ifndef V8_COMPILER_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
 #include "src/base/flags.h"
 #include "src/machine-type.h"
 
@@ skipping 317 matching lines @@
   // Access to the machine stack.
   const Operator* LoadStackPointer();
   const Operator* LoadFramePointer();
   const Operator* LoadParentFramePointer();
 
   // checked-load heap, index, length
   const Operator* CheckedLoad(CheckedLoadRepresentation);
   // checked-store heap, index, length, value
   const Operator* CheckedStore(CheckedStoreRepresentation);
 
-  // atomic-load [base + index]
-  const Operator* AtomicLoad(LoadRepresentation rep);
-
   // Target machine word-size assumed by this builder.
   bool Is32() const { return word() == MachineRepresentation::kWord32; }
   bool Is64() const { return word() == MachineRepresentation::kWord64; }
   MachineRepresentation word() const { return word_; }
 
 // Pseudo operators that translate to 32/64-bit operators depending on the
 // word-size of the target machine assumed by this builder.
 #define PSEUDO_OP_LIST(V) \
   V(Word, And)            \
   V(Word, Or)             \
@@ skipping 31 matching lines @@
 };
 
 
 DEFINE_OPERATORS_FOR_FLAGS(MachineOperatorBuilder::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_OPERATOR_H_