Reland of "🏄 [heap] Add page evacuation mode for new->old"

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 1747 matching lines @@
     return NULL;
   }
 
   // String is still reachable.
   return String::cast(first_word.ToForwardingAddress());
 }
 
 
 void Heap::UpdateNewSpaceReferencesInExternalStringTable(
     ExternalStringTableUpdaterCallback updater_func) {
-#ifdef VERIFY_HEAP
-  if (FLAG_verify_heap) {
-    external_string_table_.Verify();
-  }
-#endif
-
   if (external_string_table_.new_space_strings_.is_empty()) return;
 
   Object** start = &external_string_table_.new_space_strings_[0];
   Object** end = start + external_string_table_.new_space_strings_.length();
   Object** last = start;
 
   for (Object** p = start; p < end; ++p) {
-    DCHECK(InFromSpace(*p));
     String* target = updater_func(this, p);
 
     if (target == NULL) continue;
 
     DCHECK(target->IsExternalString());
 
     if (InNewSpace(target)) {
       // String is still in new space.  Update the table entry.
       *last = target;
       ++last;
@@ skipping 4418 matching lines @@
 
 void KeyedLookupCache::Clear() {
   for (int index = 0; index < kLength; index++) keys_[index].map = NULL;
 }
 
 
 void DescriptorLookupCache::Clear() {
   for (int index = 0; index < kLength; index++) keys_[index].source = NULL;
 }
 
-
 void Heap::ExternalStringTable::CleanUp() {
   int last = 0;
   for (int i = 0; i < new_space_strings_.length(); ++i) {
     if (new_space_strings_[i] == heap_->the_hole_value()) {
       continue;
     }
     DCHECK(new_space_strings_[i]->IsExternalString());
     if (heap_->InNewSpace(new_space_strings_[i])) {
       new_space_strings_[last++] = new_space_strings_[i];
     } else {
@@ skipping 14 matching lines @@
   }
   old_space_strings_.Rewind(last);
   old_space_strings_.Trim();
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     Verify();
   }
 #endif
 }
 
-
 void Heap::ExternalStringTable::TearDown() {
   for (int i = 0; i < new_space_strings_.length(); ++i) {
     heap_->FinalizeExternalString(ExternalString::cast(new_space_strings_[i]));
   }
   new_space_strings_.Free();
   for (int i = 0; i < old_space_strings_.length(); ++i) {
     heap_->FinalizeExternalString(ExternalString::cast(old_space_strings_[i]));
   }
   old_space_strings_.Free();
 }
@@ skipping 168 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8