Share literals arrays per <NativeContext, SharedFunctionInfo> pair.

src/objects.h

 // Copyright 2012 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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 6270 matching lines @@
 
   // [code]: Function code.
   DECL_ACCESSORS(code, Code)
   inline void ReplaceCode(Code* code);
 
   // [optimized_code_map]: Map from native context to optimized code
   // and a shared literals array or Smi(0) if none.
   DECL_ACCESSORS(optimized_code_map, Object)
 
   // Returns entry from optimized code map for specified context and OSR entry.
-  // Note that {code == nullptr} indicates no matching entry has been found,
-  // whereas {literals == nullptr} indicates the code is context-independent.
+  // The result is either kNotFound, kSharedCodeIndex for context-independent
+  // entry or a start index of the context-dependent entry.
+  int SearchOptimizedCodeMapEntry(Context* native_context,

[Michael Starzinger, 2015/09/22 10:44:39]

I think we should avoid exposing this function providing a raw index into the
map. We had such an interface before and it turned out to be a nightmare (which
is why I added the CodeAndLiterals struct). Can we make this function local to
objects.cc by putting it into an anonymous namespace there?

[Igor Sheludko, 2015/09/22 12:58:11]

The implementation uses a lot of internal SFI stuff. What about just moving the
method to private part?

[Michael Starzinger, 2015/09/23 08:14:22]

Acknowledged. Yep, works for me.

+                                  BailoutId osr_ast_id);
+  // Returns entry from optimized code map for specified context and OSR entry.
+  // Note that {code == nullptr, literals == nullptr} indicates no matching
+  // entry has been found, whereas {code, literals == nullptr} indicates that
+  // code is context-independent.
   CodeAndLiterals SearchOptimizedCodeMap(Context* native_context,
                                          BailoutId osr_ast_id);
 
   // Clear optimized code map.
   void ClearOptimizedCodeMap();
 
-  // Removed a specific optimized code object from the optimized code map.
+  // Removes a specific optimized code object from the optimized code map.
+  // In case of non-OSR the code reference is cleared from the cache entry but
+  // the entry itself is left in the map in order to proceed sharing literals.
   void EvictFromOptimizedCodeMap(Code* optimized_code, const char* reason);
 
   // Trims the optimized code map after entries have been removed.
   void TrimOptimizedCodeMap(int shrink_by);
 
   // Add a new entry to the optimized code map for context-independent code.
   static void AddSharedCodeToOptimizedCodeMap(Handle<SharedFunctionInfo> shared,
                                               Handle<Code> code);
 
   // Add a new entry to the optimized code map for context-dependent code.
+  // If |code| is an empty handle then an entry is added to map
+  // |native_context, osr_ast_id| pair to |literals| array.
   static void AddToOptimizedCodeMap(Handle<SharedFunctionInfo> shared,
                                     Handle<Context> native_context,
                                     Handle<Code> code,
                                     Handle<FixedArray> literals,
                                     BailoutId osr_ast_id);
 
   // Set up the link between shared function info and the script. The shared
   // function info is added to the list on the script.
   static void SetScript(Handle<SharedFunctionInfo> shared,
                         Handle<Object> script_object);
 
   // Layout description of the optimized code map.
   static const int kNextMapIndex = 0;
   static const int kSharedCodeIndex = 1;
   static const int kEntriesStart = 2;
   static const int kContextOffset = 0;
   static const int kCachedCodeOffset = 1;
   static const int kLiteralsOffset = 2;
   static const int kOsrAstIdOffset = 3;
   static const int kEntryLength = 4;
   static const int kInitialLength = kEntriesStart + kEntryLength;
 
+  static const int kNotFound = -1;
+
   // [scope_info]: Scope info.
   DECL_ACCESSORS(scope_info, ScopeInfo)
 
   // [construct stub]: Code stub for constructing instances of this function.
   DECL_ACCESSORS(construct_stub, Code)
 
   // Returns if this function has been compiled to native code yet.
   inline bool is_compiled();
 
   // [length]: The function length - usually the number of declared parameters.
@@ skipping 4219 matching lines @@
 
   Isolate* isolate_;
   Handle<FixedArray> keys_;
   Handle<OrderedHashSet> set_;
   int length_;
   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
 };
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_