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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/ast/ast.h"
      9 #include "src/handles.h"
     10 #include "src/objects.h"
     11 #include "src/zone.h"
     12 
     13 namespace v8 {
     14 namespace internal {
     15 
     16 
     17 // AllocationSiteContext is the base class for walking and copying a nested
     18 // boilerplate with AllocationSite and AllocationMemento support.
     19 class AllocationSiteContext {
     20  public:
     21   explicit AllocationSiteContext(Isolate* isolate) {
     22     isolate_ = isolate;
     23   }
     24 
     25   Handle<AllocationSite> top() { return top_; }
     26   Handle<AllocationSite> current() { return current_; }
     27 
     28   bool ShouldCreateMemento(Handle<JSObject> object) { return false; }
     29 
     30   Isolate* isolate() { return isolate_; }
     31 
     32  protected:
     33   void update_current_site(AllocationSite* site) {
     34     *(current_.location()) = site;
     35   }
     36 
     37   void InitializeTraversal(Handle<AllocationSite> site) {
     38     top_ = site;
     39     current_ = Handle<AllocationSite>::New(*top_, isolate());
     40   }
     41 
     42  private:
     43   Isolate* isolate_;
     44   Handle<AllocationSite> top_;
     45   Handle<AllocationSite> current_;
     46 };
     47 
     48 
     49 // AllocationSiteCreationContext aids in the creation of AllocationSites to
     50 // accompany object literals.
     51 class AllocationSiteCreationContext : public AllocationSiteContext {
     52  public:
     53   explicit AllocationSiteCreationContext(Isolate* isolate)
     54       : AllocationSiteContext(isolate) { }
     55 
     56   Handle<AllocationSite> EnterNewScope();
     57   void ExitScope(Handle<AllocationSite> site, Handle<JSObject> object);
     58 };
     59 
     60 
     61 // AllocationSiteUsageContext aids in the creation of AllocationMementos placed
     62 // behind some/all components of a copied object literal.
     63 class AllocationSiteUsageContext : public AllocationSiteContext {
     64  public:
     65   AllocationSiteUsageContext(Isolate* isolate, Handle<AllocationSite> site,
     66                              bool activated)
     67       : AllocationSiteContext(isolate),
     68         top_site_(site),
     69         activated_(activated) { }
     70 
     71   inline Handle<AllocationSite> EnterNewScope() {
     72     if (top().is_null()) {
     73       InitializeTraversal(top_site_);
     74     } else {
     75       // Advance current site
     76       Object* nested_site = current()->nested_site();
     77       // Something is wrong if we advance to the end of the list here.
     78       update_current_site(AllocationSite::cast(nested_site));
     79     }
     80     return Handle<AllocationSite>(*current(), isolate());
     81   }
     82 
     83   inline void ExitScope(Handle<AllocationSite> scope_site,
     84                         Handle<JSObject> object) {
     85     // This assert ensures that we are pointing at the right sub-object in a
     86     // recursive walk of a nested literal.
     87     DCHECK(object.is_null() || *object == scope_site->transition_info());
     88   }
     89 
     90   bool ShouldCreateMemento(Handle<JSObject> object);
     91 
     92  private:
     93   Handle<AllocationSite> top_site_;
     94   bool activated_;
     95 };
     96 
     97 
     98 }  // namespace internal
     99 }  // namespace v8
    100 
    101 #endif  // V8_ALLOCATION_SITE_SCOPES_H_
    102