Get the speed back in new context creation after it was tanked

src/serialize.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 741 matching lines @@
 
 
 static const int kUnknownOffsetFromStart = -1;
 
 
 void Deserializer::ReadChunk(Object** current,
                              Object** limit,
                              int source_space,
                              Address current_object_address) {
   Isolate* const isolate = isolate_;
+  bool write_barrier_needed = (current_object_address != NULL &&
+                               source_space != NEW_SPACE &&
+                               source_space != CELL_SPACE &&
+                               source_space == OLD_DATA_SPACE);
   while (current < limit) {
     int data = source_->Get();
     switch (data) {
 #define CASE_STATEMENT(where, how, within, space_number)                       \
       case where + how + within + space_number:                                \
       ASSERT((where & ~kPointedToMask) == 0);                                  \
       ASSERT((how & ~kHowToCodeMask) == 0);                                    \
       ASSERT((within & ~kWhereToPointMask) == 0);                              \
       ASSERT((space_number & ~kSpaceMask) == 0);
 
 #define CASE_BODY(where, how, within, space_number_if_any, offset_from_start)  \
       {                                                                        \
         bool emit_write_barrier = false;                                       \
         bool current_was_incremented = false;                                  \
         int space_number =  space_number_if_any == kAnyOldSpace ?              \
                             (data & kSpaceMask) : space_number_if_any;         \
         if (where == kNewObject && how == kPlain && within == kStartOfObject) {\
           ASSIGN_DEST_SPACE(space_number)                                      \
           ReadObject(space_number, dest_space, current);                       \
-          emit_write_barrier = (space_number == NEW_SPACE &&                   \
-                                source_space != NEW_SPACE &&                   \
-                                source_space != CELL_SPACE);                   \
+          emit_write_barrier = (space_number == NEW_SPACE);                    \
         } else {                                                               \
           Object* new_object = NULL;  /* May not be a real Object pointer. */  \
           if (where == kNewObject) {                                           \
             ASSIGN_DEST_SPACE(space_number)                                    \
             ReadObject(space_number, dest_space, &new_object);                 \
           } else if (where == kRootArray) {                                    \
-            if (source_space != CELL_SPACE &&                                  \
-                source_space != CODE_SPACE &&                                  \
-                source_space != OLD_DATA_SPACE) {                              \
-              emit_write_barrier = true;                                       \
-            }                                                                  \
+            emit_write_barrier = true;                                         \
             int root_id = source_->GetInt();                                   \
             new_object = isolate->heap()->roots_array_start()[root_id];        \
           } else if (where == kPartialSnapshotCache) {                         \
-            if (source_space != CELL_SPACE &&                                  \
-                source_space != CODE_SPACE &&                                  \
-                source_space != OLD_DATA_SPACE) {                              \
-              emit_write_barrier = true;                                       \
-            }                                                                  \
+            emit_write_barrier = true;                                         \
             int cache_index = source_->GetInt();                               \
             new_object = isolate->serialize_partial_snapshot_cache()           \
                 [cache_index];                                                 \
           } else if (where == kExternalReference) {                            \
             int reference_id = source_->GetInt();                              \
             Address address = external_reference_decoder_->                    \
                 Decode(reference_id);                                          \
             new_object = reinterpret_cast<Object*>(address);                   \
           } else if (where == kBackref) {                                      \
-            emit_write_barrier = (space_number == NEW_SPACE &&                 \
-                                  source_space != NEW_SPACE &&                 \
-                                  source_space != CELL_SPACE);                 \
+            emit_write_barrier = (space_number == NEW_SPACE);                  \
             new_object = GetAddressFromEnd(data & kSpaceMask);                 \
           } else {                                                             \
             ASSERT(where == kFromStart);                                       \
             if (offset_from_start == kUnknownOffsetFromStart) {                \
-              emit_write_barrier = (space_number == NEW_SPACE &&               \
-                                    source_space != NEW_SPACE &&               \
-                                    source_space != CELL_SPACE);               \
+              emit_write_barrier = (space_number == NEW_SPACE);                \
               new_object = GetAddressFromStart(data & kSpaceMask);             \
             } else {                                                           \
               Address object_address = pages_[space_number][0] +               \
                   (offset_from_start << kObjectAlignmentBits);                 \
               new_object = HeapObject::FromAddress(object_address);            \
             }                                                                  \
           }                                                                    \
           if (within == kFirstInstruction) {                                   \
             Code* new_code_object = reinterpret_cast<Code*>(new_object);       \
             new_object = reinterpret_cast<Object*>(                            \
                 new_code_object->instruction_start());                         \
           }                                                                    \
           if (how == kFromCode) {                                              \
             Address location_of_branch_data =                                  \
                 reinterpret_cast<Address>(current);                            \
             Assembler::set_target_at(location_of_branch_data,                  \
                                      reinterpret_cast<Address>(new_object));   \
             if (within == kFirstInstruction) {                                 \
               location_of_branch_data += Assembler::kCallTargetSize;           \
               current = reinterpret_cast<Object**>(location_of_branch_data);   \
               current_was_incremented = true;                                  \
             }                                                                  \
           } else {                                                             \
             *current = new_object;                                             \
           }                                                                    \
         }                                                                      \
-        if (emit_write_barrier && current_object_address != NULL) {            \
+        if (emit_write_barrier && write_barrier_needed) {                      \
           Address current_address = reinterpret_cast<Address>(current);        \
           isolate->heap()->RecordWrite(                                        \
               current_object_address,                                          \
               static_cast<int>(current_address - current_object_address));     \
         }                                                                      \
         if (!current_was_incremented) {                                        \
-          current++;   /* Increment current if it wasn't done above. */        \
+          current++;                                                           \
         }                                                                      \
         break;                                                                 \
       }                                                                        \
 
 // This generates a case and a body for each space.  The large object spaces are
 // very rare in snapshots so they are grouped in one body.
 #define ONE_PER_SPACE(where, how, within)                                      \
   CASE_STATEMENT(where, how, within, NEW_SPACE)                                \
   CASE_BODY(where, how, within, NEW_SPACE, kUnknownOffsetFromStart)            \
   CASE_STATEMENT(where, how, within, OLD_DATA_SPACE)                           \
@@ skipping 785 matching lines @@
       fullness_[space] = RoundUp(fullness_[space], Page::kPageSize);
     }
   }
   int allocation_address = fullness_[space];
   fullness_[space] = allocation_address + size;
   return allocation_address;
 }
 
 
 } }  // namespace v8::internal