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      1 // Copyright 2013 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_ALLOCATION_SITE_SCOPES_H_
     29 #define V8_ALLOCATION_SITE_SCOPES_H_
     30 
     31 #include "ast.h"
     32 #include "handles.h"
     33 #include "objects.h"
     34 #include "zone.h"
     35 
     36 namespace v8 {
     37 namespace internal {
     38 
     39 
     40 // AllocationSiteContext is the base class for walking and copying a nested
     41 // boilerplate with AllocationSite and AllocationMemento support.
     42 class AllocationSiteContext {
     43  public:
     44   explicit AllocationSiteContext(Isolate* isolate) {
     45     isolate_ = isolate;
     46   };
     47 
     48   Handle<AllocationSite> top() { return top_; }
     49   Handle<AllocationSite> current() { return current_; }
     50 
     51   bool ShouldCreateMemento(Handle<JSObject> object) { return false; }
     52 
     53   Isolate* isolate() { return isolate_; }
     54 
     55  protected:
     56   void update_current_site(AllocationSite* site) {
     57     *(current_.location()) = site;
     58   }
     59 
     60   void InitializeTraversal(Handle<AllocationSite> site) {
     61     top_ = site;
     62     current_ = Handle<AllocationSite>(*top_, isolate());
     63   }
     64 
     65  private:
     66   Isolate* isolate_;
     67   Handle<AllocationSite> top_;
     68   Handle<AllocationSite> current_;
     69 };
     70 
     71 
     72 // AllocationSiteCreationContext aids in the creation of AllocationSites to
     73 // accompany object literals.
     74 class AllocationSiteCreationContext : public AllocationSiteContext {
     75  public:
     76   explicit AllocationSiteCreationContext(Isolate* isolate)
     77       : AllocationSiteContext(isolate) { }
     78 
     79   Handle<AllocationSite> EnterNewScope();
     80   void ExitScope(Handle<AllocationSite> site, Handle<JSObject> object);
     81 };
     82 
     83 
     84 // AllocationSiteUsageContext aids in the creation of AllocationMementos placed
     85 // behind some/all components of a copied object literal.
     86 class AllocationSiteUsageContext : public AllocationSiteContext {
     87  public:
     88   AllocationSiteUsageContext(Isolate* isolate, Handle<AllocationSite> site,
     89                              bool activated)
     90       : AllocationSiteContext(isolate),
     91         top_site_(site),
     92         activated_(activated) { }
     93 
     94   inline Handle<AllocationSite> EnterNewScope() {
     95     if (top().is_null()) {
     96       InitializeTraversal(top_site_);
     97     } else {
     98       // Advance current site
     99       Object* nested_site = current()->nested_site();
    100       // Something is wrong if we advance to the end of the list here.
    101       ASSERT(nested_site->IsAllocationSite());
    102       update_current_site(AllocationSite::cast(nested_site));
    103     }
    104     return Handle<AllocationSite>(*current(), isolate());
    105   }
    106 
    107   inline void ExitScope(Handle<AllocationSite> scope_site,
    108                         Handle<JSObject> object) {
    109     // This assert ensures that we are pointing at the right sub-object in a
    110     // recursive walk of a nested literal.
    111     ASSERT(object.is_null() || *object == scope_site->transition_info());
    112   }
    113 
    114   bool ShouldCreateMemento(Handle<JSObject> object);
    115 
    116  private:
    117   Handle<AllocationSite> top_site_;
    118   bool activated_;
    119 };
    120 
    121 
    122 } }  // namespace v8::internal
    123 
    124 #endif  // V8_ALLOCATION_SITE_SCOPES_H_
    125