Omit kernel data from AOT snapshot

Omit kernel function bodies when writing AOT snapshot. Saves 2.7MB (16%) on the snapshot size of Flutter Gallery.

Bug: #30616
Change-Id: I7ab40d13e43607fe7c68670f8e923807b9cea37f
Reviewed-on: https://dart-review.googlesource.com/5220
Reviewed-by: Vyacheslav Egorov <[email protected]>
Reviewed-by: Siva Chandra <[email protected]>

Author: askeksa

runtime/vm/clustered_snapshot.cc

@@ -506,7 +506,7 @@ class FunctionSerializationCluster : public SerializationCluster {
     objects_.Add(func);
 
     RawObject** from = func->from();
-    RawObject** to = func->to_snapshot();
+    RawObject** to = func->to_snapshot(s->kind());
     for (RawObject** p = from; p <= to; p++) {
       s->Push(*p);
     }
@@ -535,7 +535,7 @@ class FunctionSerializationCluster : public SerializationCluster {
     for (intptr_t i = 0; i < count; i++) {
       RawFunction* func = objects_[i];
       RawObject** from = func->from();
-      RawObject** to = func->to_snapshot();
+      RawObject** to = func->to_snapshot(s->kind());
       for (RawObject** p = from; p <= to; p++) {
         s->WriteRef(*p);
       }
@@ -601,7 +601,7 @@ class FunctionDeserializationCluster : public DeserializationCluster {
       Deserializer::InitializeHeader(func, kFunctionCid,
                                      Function::InstanceSize(), is_vm_object);
       RawObject** from = func->from();
-      RawObject** to_snapshot = func->to_snapshot();
+      RawObject** to_snapshot = func->to_snapshot(d->kind());
       RawObject** to = func->to();
       for (RawObject** p = from; p <= to_snapshot; p++) {
         *p = d->ReadRef();

runtime/vm/raw_object.h

@@ -849,8 +849,21 @@ class RawFunction : public RawObject {
   RawTypeArguments* type_parameters_;  // Array of TypeParameter.
   RawObject* data_;  // Additional data specific to the function kind.
   RawTypedData* kernel_data_;
-  RawObject** to_snapshot() {
-    return reinterpret_cast<RawObject**>(&ptr()->kernel_data_);
+  RawObject** to_snapshot(Snapshot::Kind kind) {
+    switch (kind) {
+      case Snapshot::kFullAOT:
+        return reinterpret_cast<RawObject**>(&ptr()->data_);
+      case Snapshot::kFull:
+      case Snapshot::kFullJIT:
+      case Snapshot::kScript:
+        return reinterpret_cast<RawObject**>(&ptr()->kernel_data_);
+      case Snapshot::kMessage:
+      case Snapshot::kNone:
+      case Snapshot::kInvalid:
+        break;
+    }
+    UNREACHABLE();
+    return NULL;
   }
   RawArray* ic_data_array_;  // ICData of unoptimized code.
   RawObject** to_no_code() {

runtime/vm/raw_object_snapshot.cc

@@ -736,7 +736,7 @@ RawFunction* Function::ReadFrom(SnapshotReader* reader,
     func.set_was_compiled(false);
 
     // Set all the object fields.
-    READ_OBJECT_FIELDS(func, func.raw()->from(), func.raw()->to_snapshot(),
+    READ_OBJECT_FIELDS(func, func.raw()->from(), func.raw()->to_snapshot(kind),
                        kAsReference);
     // Initialize all fields that are not part of the snapshot.
     bool is_optimized = func.usage_counter() != 0;
@@ -810,7 +810,7 @@ void RawFunction::WriteTo(SnapshotWriter* writer,
 
     // Write out all the object pointer fields.
     SnapshotWriterVisitor visitor(writer, kAsReference);
-    visitor.VisitPointers(from(), to_snapshot());
+    visitor.VisitPointers(from(), to_snapshot(kind));
     if (is_optimized) {
       // Write out the ic data array as the function is optimized.
       writer->WriteObjectImpl(ptr()->ic_data_array_, kAsReference);