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

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 5232ba1649c326afa88be54de16acd211b935fc0..e3e386b78525f28a0d210259e2297cfa9df12792 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -6219,7 +6219,7 @@ void DescriptorLookupCache::Clear() {
   for (int index = 0; index < kLength; index++) keys_[index].source = NULL;
 }
 
-
+template <Heap::ExternalStringTable::CleanupMode mode>
 void Heap::ExternalStringTable::CleanUp() {
   int last = 0;
   for (int i = 0; i < new_space_strings_.length(); ++i) {
@@ -6236,17 +6236,19 @@ void Heap::ExternalStringTable::CleanUp() {
   new_space_strings_.Rewind(last);
   new_space_strings_.Trim();
 
-  last = 0;
-  for (int i = 0; i < old_space_strings_.length(); ++i) {
-    if (old_space_strings_[i] == heap_->the_hole_value()) {
-      continue;
+  if (mode == CleanupMode::kFull) {
+    last = 0;
+    for (int i = 0; i < old_space_strings_.length(); ++i) {
+      if (old_space_strings_[i] == heap_->the_hole_value()) {
+        continue;
+      }
+      DCHECK(old_space_strings_[i]->IsExternalString());
+      DCHECK(!heap_->InNewSpace(old_space_strings_[i]));
+      old_space_strings_[last++] = old_space_strings_[i];
     }
-    DCHECK(old_space_strings_[i]->IsExternalString());
-    DCHECK(!heap_->InNewSpace(old_space_strings_[i]));
-    old_space_strings_[last++] = old_space_strings_[i];
+    old_space_strings_.Rewind(last);
+    old_space_strings_.Trim();
   }
-  old_space_strings_.Rewind(last);
-  old_space_strings_.Trim();
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     Verify();
@@ -6254,6 +6256,10 @@ void Heap::ExternalStringTable::CleanUp() {
 #endif
 }
 
+template void Heap::ExternalStringTable::CleanUp<
+    Heap::ExternalStringTable::CleanupMode::kFull>();
+template void Heap::ExternalStringTable::CleanUp<
+    Heap::ExternalStringTable::CleanupMode::kPromoteOnly>();
 
 void Heap::ExternalStringTable::TearDown() {
   for (int i = 0; i < new_space_strings_.length(); ++i) {