[heap] Add detailed object stats for maps.

This introduces new virtual instance types to further diagnose what's
going on in MapSpace, namely:

 - MAP_ABANDONED_PROTOTYPE_TYPE includes all the abandoned (fast-mode)
   prototype maps.
 - MAP_DEPRECATED_TYPE includes all the deprecated (fast-mode) maps.
 - MAP_DICTIONARY_TYPE includes all the dictionary-mode maps.
 - MAP_PROTOTYPE_DICTIONARY_TYPE includes all the prototype maps in
   dictionary-mode.
 - MAP_PROTOTYPE_TYPE includes all the prototype maps in fast-mode.
 - MAP_STABLE_TYPE includes all the (fast-mode) stable (leaf) maps.

Those maps who don't fall into any of the buckets above are categorized
as MAP_TYPE (as before).

The naming was chosen like this to make it possible to filter for the
relevant maps in the object stats via 'MAP_.*_TYPE'.

Bug: v8:7266
Change-Id: I233734e96a390ddb391bfff8a34a8fec842d1f7f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1554685Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60651}

src/heap/object-stats.cc

@@ -776,6 +776,34 @@ bool ObjectStatsCollectorImpl::SameLiveness(HeapObject obj1, HeapObject obj2) {
 void ObjectStatsCollectorImpl::RecordVirtualMapDetails(Map map) {
   // TODO(mlippautz): map->dependent_code(): DEPENDENT_CODE_TYPE.
 
+  // For Map we want to distinguish between various different states
+  // to get a better picture of what's going on in MapSpace. This
+  // method computes the virtual instance type to use for a given map,
+  // using MAP_TYPE for regular maps that aren't special in any way.
+  if (map->is_prototype_map()) {
+    if (map->is_dictionary_map()) {
+      RecordSimpleVirtualObjectStats(
+          HeapObject(), map, ObjectStats::MAP_PROTOTYPE_DICTIONARY_TYPE);
+    } else if (map->is_abandoned_prototype_map()) {
+      RecordSimpleVirtualObjectStats(HeapObject(), map,
+                                     ObjectStats::MAP_ABANDONED_PROTOTYPE_TYPE);
+    } else {
+      RecordSimpleVirtualObjectStats(HeapObject(), map,
+                                     ObjectStats::MAP_PROTOTYPE_TYPE);
+    }
+  } else if (map->is_deprecated()) {
+    RecordSimpleVirtualObjectStats(HeapObject(), map,
+                                   ObjectStats::MAP_DEPRECATED_TYPE);
+  } else if (map->is_dictionary_map()) {
+    RecordSimpleVirtualObjectStats(HeapObject(), map,
+                                   ObjectStats::MAP_DICTIONARY_TYPE);
+  } else if (map->is_stable()) {
+    RecordSimpleVirtualObjectStats(HeapObject(), map,
+                                   ObjectStats::MAP_STABLE_TYPE);
+  } else {
+    // This will be logged as MAP_TYPE in Phase2.
+  }
+
   DescriptorArray array = map->instance_descriptors();
   if (map->owns_descriptors() &&
       array != ReadOnlyRoots(heap_).empty_descriptor_array()) {

src/heap/object-stats.h

@@ -45,6 +45,12 @@
   V(JS_ARRAY_BOILERPLATE_TYPE)                   \
   V(JS_COLLECTION_TABLE_TYPE)                    \
   V(JS_OBJECT_BOILERPLATE_TYPE)                  \
+  V(MAP_ABANDONED_PROTOTYPE_TYPE)                \
+  V(MAP_DEPRECATED_TYPE)                         \
+  V(MAP_DICTIONARY_TYPE)                         \
+  V(MAP_PROTOTYPE_DICTIONARY_TYPE)               \
+  V(MAP_PROTOTYPE_TYPE)                          \
+  V(MAP_STABLE_TYPE)                             \
   V(NOSCRIPT_SHARED_FUNCTION_INFOS_TYPE)         \
   V(NUMBER_STRING_CACHE_TYPE)                    \
   V(OBJECT_PROPERTY_DICTIONARY_TYPE)             \