Introduce code flushing of RegExp code.

src/mark-compact.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 406 matching lines @@
                                       void>::Visit);
 
     table_.Register(kVisitCode, &VisitCode);
 
     table_.Register(kVisitSharedFunctionInfo,
                     &VisitSharedFunctionInfoAndFlushCode);
 
     table_.Register(kVisitJSFunction,
                     &VisitJSFunctionAndFlushCode);
 
+    table_.Register(kVisitJSRegExp,
+                    &VisitRegExpAndFlushCode);
+
     table_.Register(kVisitPropertyCell,
                     &FixedBodyVisitor<StaticMarkingVisitor,
                                       JSGlobalPropertyCell::BodyDescriptor,
                                       void>::Visit);
 
     table_.RegisterSpecializations<DataObjectVisitor,
                                    kVisitDataObject,
                                    kVisitDataObjectGeneric>();
 
     table_.RegisterSpecializations<JSObjectVisitor,
@@ skipping 120 matching lines @@
     reinterpret_cast<Code*>(object)->CodeIterateBody<StaticMarkingVisitor>(
         map->heap());
   }
 
   // Code flushing support.
 
   // How many collections newly compiled code object will survive before being
   // flushed.
   static const int kCodeAgeThreshold = 5;
 
+  static const int kRegExpCodeThreshold = 5;
+
   inline static bool HasSourceCode(Heap* heap, SharedFunctionInfo* info) {
     Object* undefined = heap->raw_unchecked_undefined_value();
     return (info->script() != undefined) &&
         (reinterpret_cast<Script*>(info->script())->source() != undefined);
   }
 
 
   inline static bool IsCompiled(JSFunction* function) {
     return function->unchecked_code() !=
         function->GetIsolate()->builtins()->builtin(Builtins::kLazyCompile);
@@ skipping 116 matching lines @@
     SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(object);
 
     if (shared->IsInobjectSlackTrackingInProgress()) shared->DetachInitialMap();
 
     FixedBodyVisitor<StaticMarkingVisitor,
                      SharedFunctionInfo::BodyDescriptor,
                      void>::Visit(map, object);
   }
 
 
+  static void UpdateRegExpCodeAgeAndFlush(Heap* heap,
+                                          JSRegExp* re,
+                                          bool is_ascii) {
+    // Make sure that the fixed array is in fact initialized on the RegExp.
+    // We could potentially trigger a GC when initializing the RegExp.
+    if (SafeMap(re->data())->instance_type() != FIXED_ARRAY_TYPE) return;
+
+    // Make sure this is a RegExp that actually contains code.
+    if (re->TypeTagUnchecked() != JSRegExp::IRREGEXP) return;
+
+    Object* code = re->DataAtUnchecked(JSRegExp::code_index(is_ascii));
+    if (!code->IsSmi() && SafeMap(code)->instance_type() == CODE_TYPE ) {
+      // Save a copy that can be reinstated if we need the code again.
+      re->SetDataAtUnchecked(JSRegExp::saved_code_index(is_ascii),
+                             code,
+                             heap);
+      re->SetDataAtUnchecked(JSRegExp::code_index(is_ascii),
+                             Smi::FromInt(heap->sweep_generation() % 256),
+                             heap);
+    } else if (code->IsSmi()) {
+      int value = Smi::cast(code)->value();
+      // The regexp has not been compiled yet.
+      if (value == JSRegExp::kUninitializedValue) return;
+
+      // Check if we should flush now.
+      if (value == (heap->sweep_generation() - kRegExpCodeThreshold) % 256) {

[Erik Corry, 2011/06/30 18:48:25]

If the lhs is negative then according to the standard the result of the %
operator can be either positive or negative.  Therefore I would prefer using &
0xff which can yield only a positive answer.  The same applies above.

[Rico, 2011/07/01 05:58:09]

Done.

+        re->SetDataAtUnchecked(JSRegExp::code_index(is_ascii),
+                               Smi::FromInt(JSRegExp::kUninitializedValue),
+                               heap);
+        re->SetDataAtUnchecked(JSRegExp::saved_code_index(is_ascii),
+                               Smi::FromInt(JSRegExp::kUninitializedValue),
+                               heap);
+      }
+    }
+  }
+
+
+  // Works by setting the current sweep_generation (as a smi) in the
+  // code object place in the data array of the RegExp and keeps a copy
+  // around that can be reinstated if we reuse the RegExp before flushing.
+  // If we did not use the code for kRegExpCodeThreshold mark sweep GCs
+  // we flush the code.
+  static void VisitRegExpAndFlushCode(Map* map, HeapObject* object) {
+    Heap* heap = map->heap();
+    MarkCompactCollector* collector = heap->mark_compact_collector();
+    if (!collector->is_code_flushing_enabled()) {
+      VisitJSRegExpFields(map, object);
+      return;
+    }
+    JSRegExp* re = reinterpret_cast<JSRegExp*>(object);
+    // Flush code or set age on both ascii and two byte code.
+    UpdateRegExpCodeAgeAndFlush(heap, re, true);
+    UpdateRegExpCodeAgeAndFlush(heap, re, false);
+    // Visit the fields of the RegExp, including the updated FixedArray.
+    VisitJSRegExpFields(map, object);
+  }
+
+
   static void VisitSharedFunctionInfoAndFlushCode(Map* map,
                                                   HeapObject* object) {
     MarkCompactCollector* collector = map->heap()->mark_compact_collector();
     if (!collector->is_code_flushing_enabled()) {
       VisitSharedFunctionInfoGeneric(map, object);
       return;
     }
     VisitSharedFunctionInfoAndFlushCodeGeneric(map, object, false);
   }
 
@@ skipping 110 matching lines @@
     }
 
     VisitPointers(heap,
                   SLOT_ADDR(object,
                             JSFunction::kCodeEntryOffset + kPointerSize),
                   SLOT_ADDR(object, JSFunction::kNonWeakFieldsEndOffset));
 
     // Don't visit the next function list field as it is a weak reference.
   }
 
+  static inline void VisitJSRegExpFields(Map* map,
+                                         HeapObject* object) {
+    int last_property_offset =
+        JSRegExp::kSize + kPointerSize * map->inobject_properties();
+    VisitPointers(map->heap(),
+                  SLOT_ADDR(object, JSRegExp::kPropertiesOffset),
+                  SLOT_ADDR(object, last_property_offset));
+  }
+
 
   static void VisitSharedFunctionInfoFields(Heap* heap,
                                             HeapObject* object,
                                             bool flush_code_candidate) {
     VisitPointer(heap, SLOT_ADDR(object, SharedFunctionInfo::kNameOffset));
 
     if (!flush_code_candidate) {
       VisitPointer(heap, SLOT_ADDR(object, SharedFunctionInfo::kCodeOffset));
     }
 
@@ skipping 2294 matching lines @@
 }
 
 
 void MarkCompactCollector::Initialize() {
   StaticPointersToNewGenUpdatingVisitor::Initialize();
   StaticMarkingVisitor::Initialize();
 }
 
 
 } }  // namespace v8::internal