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      1 // Copyright 2013 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_ALLOCATION_SITE_SCOPES_H_
      6 #define V8_ALLOCATION_SITE_SCOPES_H_
      7 
      8 #include "src/handles.h"
      9 #include "src/objects.h"
     10 
     11 namespace v8 {
     12 namespace internal {
     13 
     14 
     15 // AllocationSiteContext is the base class for walking and copying a nested
     16 // boilerplate with AllocationSite and AllocationMemento support.
     17 class AllocationSiteContext {
     18  public:
     19   explicit AllocationSiteContext(Isolate* isolate) {
     20     isolate_ = isolate;
     21   }
     22 
     23   Handle<AllocationSite> top() { return top_; }
     24   Handle<AllocationSite> current() { return current_; }
     25 
     26   bool ShouldCreateMemento(Handle<JSObject> object) { return false; }
     27 
     28   Isolate* isolate() { return isolate_; }
     29 
     30  protected:
     31   void update_current_site(AllocationSite* site) {
     32     *(current_.location()) = site;
     33   }
     34 
     35   void InitializeTraversal(Handle<AllocationSite> site) {
     36     top_ = site;
     37     current_ = Handle<AllocationSite>::New(*top_, isolate());
     38   }
     39 
     40  private:
     41   Isolate* isolate_;
     42   Handle<AllocationSite> top_;
     43   Handle<AllocationSite> current_;
     44 };
     45 
     46 
     47 // AllocationSiteCreationContext aids in the creation of AllocationSites to
     48 // accompany object literals.
     49 class AllocationSiteCreationContext : public AllocationSiteContext {
     50  public:
     51   explicit AllocationSiteCreationContext(Isolate* isolate)
     52       : AllocationSiteContext(isolate) { }
     53 
     54   Handle<AllocationSite> EnterNewScope();
     55   void ExitScope(Handle<AllocationSite> site, Handle<JSObject> object);
     56 };
     57 
     58 
     59 // AllocationSiteUsageContext aids in the creation of AllocationMementos placed
     60 // behind some/all components of a copied object literal.
     61 class AllocationSiteUsageContext : public AllocationSiteContext {
     62  public:
     63   AllocationSiteUsageContext(Isolate* isolate, Handle<AllocationSite> site,
     64                              bool activated)
     65       : AllocationSiteContext(isolate),
     66         top_site_(site),
     67         activated_(activated) { }
     68 
     69   inline Handle<AllocationSite> EnterNewScope() {
     70     if (top().is_null()) {
     71       InitializeTraversal(top_site_);
     72     } else {
     73       // Advance current site
     74       Object* nested_site = current()->nested_site();
     75       // Something is wrong if we advance to the end of the list here.
     76       update_current_site(AllocationSite::cast(nested_site));
     77     }
     78     return Handle<AllocationSite>(*current(), isolate());
     79   }
     80 
     81   inline void ExitScope(Handle<AllocationSite> scope_site,
     82                         Handle<JSObject> object) {
     83     // This assert ensures that we are pointing at the right sub-object in a
     84     // recursive walk of a nested literal.
     85     DCHECK(object.is_null() || *object == scope_site->transition_info());
     86   }
     87 
     88   bool ShouldCreateMemento(Handle<JSObject> object);
     89 
     90  private:
     91   Handle<AllocationSite> top_site_;
     92   bool activated_;
     93 };
     94 
     95 
     96 }  // namespace internal
     97 }  // namespace v8
     98 
     99 #endif  // V8_ALLOCATION_SITE_SCOPES_H_
    100