[ic] Reorder feedback vector to have deprecated maps at the end

This will allow minimorphic ICs the best chance of succeeding as they
only check the first FLAG_max_minimorphic_map_checks maps in the
feedback vector.

Bug: v8:10582
Change-Id: I1c78dcc8b6f7072b2563fdc8bf69b349a99c4bb5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2400340
Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70003}

src/ic/ic.cc

@@ -574,7 +574,7 @@ bool IC::UpdatePolymorphicIC(Handle<Name> name,
 
   std::vector<MapAndHandler> maps_and_handlers;
   maps_and_handlers.reserve(FLAG_max_valid_polymorphic_map_count);
-  int deprecated_maps = 0;
+  std::vector<MapAndHandler> deprecated_maps_and_handlers;
   int handler_to_overwrite = -1;
 
   {
@@ -584,13 +584,18 @@ bool IC::UpdatePolymorphicIC(Handle<Name> name,
       if (it.handler()->IsCleared()) continue;
       MaybeObjectHandle existing_handler = handle(it.handler(), isolate());
       Handle<Map> existing_map = handle(it.map(), isolate());
-      maps_and_handlers.push_back(
-          MapAndHandler(existing_map, existing_handler));
 
       if (existing_map->is_deprecated()) {
         // Filter out deprecated maps to ensure their instances get migrated.
-        ++deprecated_maps;
-      } else if (map.is_identical_to(existing_map)) {
+        deprecated_maps_and_handlers.push_back(
+            MapAndHandler(existing_map, existing_handler));
+        continue;
+      }
+
+      maps_and_handlers.push_back(
+          MapAndHandler(existing_map, existing_handler));
+
+      if (map.is_identical_to(existing_map)) {
         // If both map and handler stayed the same (and the name is also the
         // same as checked above, for keyed accesses), we're not progressing
         // in the lattice and need to go MEGAMORPHIC instead. There's one
@@ -612,9 +617,20 @@ bool IC::UpdatePolymorphicIC(Handle<Name> name,
 
       i++;
     }
+    DCHECK_LE(i, maps_and_handlers.size());
+  }
+
+  // Reorder the deprecated maps to be at the end, so that
+  // minimorphic ICs have the best chance of succeeding as they only
+  // check the first FLAG_max_minimorphic_map_checks maps.
+  if (deprecated_maps_and_handlers.size() > 0) {
+    maps_and_handlers.insert(maps_and_handlers.end(),
+                             deprecated_maps_and_handlers.begin(),
+                             deprecated_maps_and_handlers.end());
   }
 
   int number_of_maps = static_cast<int>(maps_and_handlers.size());
+  int deprecated_maps = static_cast<int>(deprecated_maps_and_handlers.size());
   int number_of_valid_maps =
       number_of_maps - deprecated_maps - (handler_to_overwrite != -1);