src/v8/src/allocation-site-scopes.h

   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 "ast.h"
   9 #include "handles.h"
  10 #include "objects.h"
  11 #include "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>(*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       ASSERT(nested_site->IsAllocationSite());
  79       update_current_site(AllocationSite::cast(nested_site));
  80     }
  81     return Handle<AllocationSite>(*current(), isolate());
  82   }
  83
  84   inline void ExitScope(Handle<AllocationSite> scope_site,
  85                         Handle<JSObject> object) {
  86     // This assert ensures that we are pointing at the right sub-object in a
  87     // recursive walk of a nested literal.
  88     ASSERT(object.is_null() || *object == scope_site->transition_info());
  89   }
  90
  91   bool ShouldCreateMemento(Handle<JSObject> object);
  92
  93  private:
  94   Handle<AllocationSite> top_site_;
  95   bool activated_;
  96 };
  97
  98
  99 } }  // namespace v8::internal
 100
 101 #endif  // V8_ALLOCATION_SITE_SCOPES_H_