[TypeFeedbackVector] Root literal arrays in function literals slots

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 53c5e18c53dc60602d28997bffa3236ec2b04ffb..80f6981ed370c13fa3c94425dd36a4299ea00122 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -5008,8 +5008,11 @@ class LiteralsArray : public FixedArray {
     return OffsetOfElementAt(index + kFirstLiteralIndex);
   }
 
+  // Returns true if the vector isn't yet installed.
+  inline bool needs_feedback_vector() const;

[Michael Starzinger, 2017/01/11 12:07:27]

suggestion: Could we negate this predicate and call it "has_feedback_vector"
instead? The current naming makes it sound like the predicate is answering the
question whether this literals arrays "will ever need a feedback vector" whereas
it actually determines whether the literals array is "currently still missing"
one. WDYT?

[mvstanton, 2017/01/11 13:14:52]

Good idea, done.

   inline TypeFeedbackVector* feedback_vector() const;
   inline void set_feedback_vector(TypeFeedbackVector* vector);
+
   inline Object* literal(int literal_index) const;
   inline void set_literal(int literal_index, Object* literal);
   inline void set_literal_undefined(int literal_index);
@@ -7150,14 +7153,6 @@ enum BuiltinFunctionId {
 };
 
 
-// Result of searching in an optimized code map of a SharedFunctionInfo. Note
-// that both {code} and {literals} can be NULL to pass search result status.
-struct CodeAndLiterals {
-  Code* code;            // Cached optimized code.
-  LiteralsArray* literals;  // Cached literals array.
-};
-
-
 // SharedFunctionInfo describes the JSFunction information that can be
 // shared by multiple instances of the function.
 class SharedFunctionInfo: public HeapObject {
@@ -7188,11 +7183,7 @@ class SharedFunctionInfo: public HeapObject {
   DECL_ACCESSORS(optimized_code_map, FixedArray)
 
   // 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);
+  Code* SearchOptimizedCodeMap(Context* native_context, BailoutId osr_ast_id);
 
   // Clear optimized code map.
   void ClearOptimizedCodeMap();
@@ -7218,7 +7209,6 @@ class SharedFunctionInfo: public HeapObject {
   static void AddToOptimizedCodeMap(Handle<SharedFunctionInfo> shared,
                                     Handle<Context> native_context,
                                     MaybeHandle<Code> code,

[Michael Starzinger, 2017/01/11 12:07:27]

Is there still a call-site left that does not pass a code? Otherwise we could
turn this into Handle<Code> instead and also drop the second sentence in the
comment above.

[mvstanton, 2017/01/11 13:14:52]

Good idea, done!

-                                    Handle<LiteralsArray> literals,
                                     BailoutId osr_ast_id);
 
   // Set up the link between shared function info and the script. The shared
@@ -7230,8 +7220,7 @@ class SharedFunctionInfo: public HeapObject {
   static const int kEntriesStart = 0;
   static const int kContextOffset = 0;
   static const int kCachedCodeOffset = 1;
-  static const int kLiteralsOffset = 2;
-  static const int kEntryLength = 3;
+  static const int kEntryLength = 2;
   static const int kInitialLength = kEntriesStart + kEntryLength;
 
   static const int kNotFound = -1;
@@ -7243,8 +7232,6 @@ class SharedFunctionInfo: public HeapObject {
   static const int kOffsetToPreviousCachedCode =
       FixedArray::kHeaderSize +
       kPointerSize * (kCachedCodeOffset - kEntryLength);
-  static const int kOffsetToPreviousLiterals =
-      FixedArray::kHeaderSize + kPointerSize * (kLiteralsOffset - kEntryLength);
 
   // [scope_info]: Scope info.
   DECL_ACCESSORS(scope_info, ScopeInfo)
@@ -8383,6 +8370,8 @@ class JSFunction: public JSObject {
   static const int kSize = kNextFunctionLinkOffset + kPointerSize;
 
  private:
+  inline bool needs_literals_array() const;

[Michael Starzinger, 2017/01/11 12:07:27]

suggestion: Likewise, I propose changing to "has_literals_array". Also I would
be OK with making this public and moving it close to the {JSFunction::literals}
accessor.

[mvstanton, 2017/01/11 13:14:52]

Done.

+
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSFunction);
 };