Cache initial (empty) ic_data arrays so that they are not repeatedly allocated. Factor out descript…

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 9c7997583372c672287080ad6e83e0de8e631cf6..9d794fb6105864c257db464731f247c4f1478a29 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -1333,6 +1333,13 @@ RawObject* SnapshotReader::ReadVMIsolateObject(intptr_t header_value) {
     }
   }
 
+  // Check if it is a singleton ICData array object.
+  for (intptr_t i = 0; i < ICData::kCachedICDataArrayCount; i++) {
+    if (object_id == (kCachedICDataArray0 + i)) {
+      return ICData::cached_icdata_arrays_[i];
+    }
+  }
+
   ASSERT(Symbols::IsVMSymbolId(object_id));
   return Symbols::GetVMSymbol(object_id);  // return VM symbol.
 }
@@ -1675,6 +1682,14 @@ bool SnapshotWriter::HandleVMIsolateObject(RawObject* rawobj) {
     }
   }
 
+  // Check if it is a singleton ICData array object.
+  for (intptr_t i = 0; i < ICData::kCachedICDataArrayCount; i++) {
+    if (rawobj == ICData::cached_icdata_arrays_[i]) {
+      WriteVMIsolateObject(kCachedICDataArray0 + i);
+      return true;
+    }
+  }
+
   if (kind() == Snapshot::kFull) {
     // Check it is a predefined symbol in the VM isolate.
     id = Symbols::LookupVMSymbol(rawobj);