[ignition] Optimize JSGenerator creation

src/code-stub-assembler.h

 // Copyright 2016 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_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 1249 matching lines @@
   Node* PageFromAddress(Node* address);
 
   // Create a new weak cell with a specified value and install it into a
   // feedback vector.
   Node* CreateWeakCellInFeedbackVector(Node* feedback_vector, Node* slot,
                                        Node* value);
 
   // Create a new AllocationSite and install it into a feedback vector.
   Node* CreateAllocationSiteInFeedbackVector(Node* feedback_vector, Node* slot);
 
+  // Given a recently allocated object {object}, with map {initial_map},
+  // initialize remaining fields appropriately to comply with slack tracking.
+  void HandleSlackTracking(Node* context, Node* object, Node* initial_map,
+                           int start_offset);
+
   enum class IndexAdvanceMode { kPre, kPost };
 
   typedef std::function<void(Node* index)> FastLoopBody;
 
   Node* BuildFastLoop(const VariableList& var_list, Node* start_index,
                       Node* end_index, const FastLoopBody& body, int increment,
                       ParameterMode parameter_mode,
                       IndexAdvanceMode advance_mode = IndexAdvanceMode::kPre);
 
   Node* BuildFastLoop(Node* start_index, Node* end_index,
@@ skipping 315 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_