More precompiled snapshotting.

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 85099cca5c331ac19b8e367b8c48f82a4de8efe0..f6b2023dc5b9750f6df942023df605e56f577a84 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -198,6 +198,8 @@ SnapshotReader::SnapshotReader(
       data_(ExternalTypedData::Handle(zone_)),
       typed_data_(TypedData::Handle(zone_)),
       code_(Code::Handle(zone_)),
+      function_(Function::Handle(zone_)),
+      megamorphic_cache_(MegamorphicCache::Handle(zone_)),
       error_(UnhandledException::Handle(zone_)),
       max_vm_isolate_object_id_(
           (kind == Snapshot::kFull) ?
@@ -664,6 +666,9 @@ RawApiError* SnapshotReader::ReadFullSnapshot() {
     for (intptr_t i = 0; i <= num_flds; i++) {
       *(object_store->from() + i) = ReadObjectImpl(kAsInlinedObject);
     }
+    if (snapshot_code_) {
+      isolate->megamorphic_cache_table()->ReadFrom(this);
+    }
     for (intptr_t i = 0; i < backward_references_->length(); i++) {
       if (!(*backward_references_)[i].is_deserialized()) {
         ReadObjectImpl(kAsInlinedObject);
@@ -1541,9 +1546,8 @@ RawApiError* VmIsolateSnapshotReader::ReadVmIsolateSnapshot() {
       ExceptionHandlers::CheckedHandle(ReadObject());  // empty exc handlers
 
 #define READ_STUB(name)                                                       \
-      *(CodeHandle()) ^= ReadObject();
-      // TODO(rmacnak):
-      // StubCode::name##_entry()->InitOnceFromSnapshot(CodeHandle())
+      *(CodeHandle()) ^= ReadObject();                                        \
+      StubCode::name##_entry_ = new StubEntry(*CodeHandle());

[siva, 2015/09/14 20:32:59]

Instead of exposing the stub code macro order here it might be better to have a
StubCode::InitOnceFromSnapshot() function which will suck in the instructions
for the various stubs and then create code objects and finalize the stubs.

This would also mean that we could continue to restrict HandleVmIsolateObjects
to just the specific ones we have instead of opening it up for all generic
objects.

(Maybe we can do this cleanup in another CL).

[rmacnak, 2015/09/15 17:56:42]

Pushed to stub_code.cc and added TODO.

       VM_STUB_CODE_LIST(READ_STUB);
 #undef READ_STUB
     }
@@ -1569,6 +1573,7 @@ IsolateSnapshotReader::IsolateSnapshotReader(const uint8_t* buffer,
                      new ZoneGrowableArray<BackRefNode>(
                          kNumInitialReferencesInFullSnapshot),
                      thread) {
+  Isolate::Current()->set_compilation_allowed(instructions_buffer_ == NULL);
 }
 
 
@@ -1996,6 +2001,10 @@ void FullSnapshotWriter::WriteIsolateFullSnapshot() {
     SnapshotWriterVisitor visitor(&writer, false);
     object_store->VisitObjectPointers(&visitor);
 
+    if (snapshot_code_) {
+      isolate_->megamorphic_cache_table()->WriteTo(&writer);
+    }

[siva, 2015/09/14 20:32:59]

Why do you order this in between the object_store objects and it's forward
references?
Maybe this is moot once you make the megamorphic cache table into a regular dart
object and stick it into the object store.

[rmacnak, 2015/09/15 17:56:42]

Dropped.

+
     // Write out all forwarded objects.
     writer.WriteForwardedObjects();