[snapshot] Print allocation stats for memory tests

Since we're not reserving memory anymore, we don't log reserved memory
when profiling serialization. So, instead log the allocation counts used
by OutputStatistics as a pseudo-reserved size.

Bug: v8:10998
Bug: chromium:1075999
Change-Id: I64dc6086b14c0e720ef8d0c1ea99a6f8ccabcf9c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2460808
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70399}

src/snapshot/serializer.cc

@@ -51,6 +51,14 @@ void Serializer::CountAllocation(Map map, int size, SnapshotSpace space) {
 #endif  // OBJECT_PRINT
 }
 
+int Serializer::TotalAllocationSize() const {
+  int sum = 0;
+  for (int space = 0; space < kNumberOfSnapshotSpaces; space++) {
+    sum += allocation_size_[space];
+  }
+  return sum;
+}
+
 void Serializer::OutputStatistics(const char* name) {
   if (!FLAG_serialization_statistics) return;
 

src/snapshot/serializer.h

@@ -169,6 +169,8 @@ class Serializer : public SerializerDeserializer {
 
   Isolate* isolate() const { return isolate_; }
 
+  int TotalAllocationSize() const;
+
  protected:
   using PendingObjectReferences = std::vector<int>*;
 

src/snapshot/snapshot.cc

@@ -348,12 +348,17 @@ v8::StartupData Snapshot::Create(
   // TODO(v8:6593): generalize rehashing, and remove this flag.
   bool can_be_rehashed = true;
 
+  std::vector<int> context_allocation_sizes;
   for (int i = 0; i < num_contexts; i++) {
     ContextSerializer context_serializer(isolate, flags, &startup_serializer,
                                          embedder_fields_serializers[i]);
     context_serializer.Serialize(&contexts->at(i), no_gc);
     can_be_rehashed = can_be_rehashed && context_serializer.can_be_rehashed();
     context_snapshots.push_back(new SnapshotData(&context_serializer));
+    if (FLAG_profile_deserialization) {
+      context_allocation_sizes.push_back(
+          context_serializer.TotalAllocationSize());
+    }
   }
 
   startup_serializer.SerializeWeakReferencesAndDeferred();
@@ -364,6 +369,17 @@ v8::StartupData Snapshot::Create(
   read_only_serializer.FinalizeSerialization();
   can_be_rehashed = can_be_rehashed && read_only_serializer.can_be_rehashed();
 
+  if (FLAG_profile_deserialization) {
+    // These prints should match the regexp in test/memory/Memory.json
+    PrintF("Deserialization will allocate:\n");
+    PrintF("%10d bytes per isolate\n",
+           read_only_serializer.TotalAllocationSize() +
+               startup_serializer.TotalAllocationSize());
+    for (int i = 0; i < num_contexts; i++) {
+      PrintF("%10d bytes per context #%d\n", context_allocation_sizes[i], i);
+    }
+  }
+
   SnapshotData read_only_snapshot(&read_only_serializer);
   SnapshotData startup_snapshot(&startup_serializer);
   v8::StartupData result =