[Atomics] code stubs for atomic operations

src/compiler/linkage.h

 // 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.
 
 #ifndef V8_COMPILER_LINKAGE_H_
 #define V8_COMPILER_LINKAGE_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/frame.h"
 #include "src/compiler/operator.h"
@@ skipping 346 matching lines @@
   }
 
   bool ParameterHasSecondaryLocation(int index) const;
   LinkageLocation GetParameterSecondaryLocation(int index) const;
 
   static int FrameStateInputCount(Runtime::FunctionId function);
 
   // Get the location where an incoming OSR value is stored.
   LinkageLocation GetOsrValueLocation(int index) const;
 
+  // A special {Parameter} index for Stub Calls that represents context.
+  static int GetStubCallContextParamIndex(int parameter_count) {
+    return parameter_count + 0;  // Parameter (arity + 0) is special.
+  }
+
   // A special {Parameter} index for JSCalls that represents the new target.
   static int GetJSCallNewTargetParamIndex(int parameter_count) {
     return parameter_count + 0;  // Parameter (arity + 0) is special.
   }
 
   // A special {Parameter} index for JSCalls that represents the argument count.
   static int GetJSCallArgCountParamIndex(int parameter_count) {
     return parameter_count + 1;  // Parameter (arity + 1) is special.
   }
 
@@ skipping 12 matching lines @@
   CallDescriptor* const incoming_;
 
   DISALLOW_COPY_AND_ASSIGN(Linkage);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_LINKAGE_H_