[Atomics] code stubs for atomic operations

src/compiler/js-intrinsic-lowering.h

Index: src/compiler/js-intrinsic-lowering.h
diff --git a/src/compiler/js-intrinsic-lowering.h b/src/compiler/js-intrinsic-lowering.h
index 1977a5847d858f6acdbf2153acfdab926e668d70..02a9c5ce5b01ac3a89fa44bf02f5ccbb879bb027 100644
--- a/src/compiler/js-intrinsic-lowering.h
+++ b/src/compiler/js-intrinsic-lowering.h
@@ -7,6 +7,7 @@
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph-reducer.h"
+#include "src/compiler/linkage.h"
 
 namespace v8 {
 namespace internal {
@@ -71,6 +72,7 @@ class JSIntrinsicLowering final : public AdvancedReducer {
   Reduction ReduceCall(Node* node);
   Reduction ReduceTailCall(Node* node);
   Reduction ReduceGetSuperConstructor(Node* node);
+  Reduction ReduceAtomicsLoad(Node* node);
 
   Reduction Change(Node* node, const Operator* op);
   Reduction Change(Node* node, const Operator* op, Node* a, Node* b);
@@ -79,7 +81,7 @@ class JSIntrinsicLowering final : public AdvancedReducer {
                    Node* d);
   Reduction ChangeToUndefined(Node* node, Node* effect = nullptr);
   Reduction Change(Node* node, Callable const& callable,
-                   int stack_parameter_count);
+                   int stack_parameter_count, CallDescriptor::Flags flags);
 
   Graph* graph() const;
   JSGraph* jsgraph() const { return jsgraph_; }