VM: Precompiled rodata snapshot.

runtime/vm/raw_object_snapshot.cc

Index: runtime/vm/raw_object_snapshot.cc
diff --git a/runtime/vm/raw_object_snapshot.cc b/runtime/vm/raw_object_snapshot.cc
index 1a617bacaf32013d55ff7e5bf5a5f43760b43420..cfa19c47beed844fcba28efd133cf85644cbe87a 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -1477,7 +1477,11 @@ RawInstructions* Instructions::ReadFrom(SnapshotReader* reader,
   ASSERT(reader->snapshot_code());
   ASSERT(kind == Snapshot::kFull);
 
+#ifdef DEBUG
   intptr_t full_tags = static_cast<uword>(reader->Read<intptr_t>());
+#else
+  intptr_t full_tags = 0;  // unused in release mode
+#endif
   intptr_t offset = reader->Read<int32_t>();
   Instructions& result =
       Instructions::ZoneHandle(reader->zone(),
@@ -1499,6 +1503,7 @@ void RawInstructions::WriteTo(SnapshotWriter* writer,
   writer->WriteVMIsolateObject(kInstructionsCid);
   writer->WriteTags(writer->GetObjectTags(this));
 
+#ifdef DEBUG
   // Instructions will be written pre-marked and in the VM heap. Write out
   // the tags we expect to find when reading the snapshot for a sanity check
   // that our offsets/alignment didn't get out of sync.
@@ -1506,6 +1511,7 @@ void RawInstructions::WriteTo(SnapshotWriter* writer,
   written_tags = RawObject::VMHeapObjectTag::update(true, written_tags);
   written_tags = RawObject::MarkBit::update(true, written_tags);
   writer->Write<intptr_t>(written_tags);
+#endif
 
   writer->Write<int32_t>(writer->GetInstructionsId(this));
 }
@@ -1643,19 +1649,11 @@ RawPcDescriptors* PcDescriptors::ReadFrom(SnapshotReader* reader,
   ASSERT(reader->snapshot_code());
   ASSERT(kind == Snapshot::kFull);
 
-  const int32_t length = reader->Read<int32_t>();
-  PcDescriptors& result =
-      PcDescriptors::ZoneHandle(reader->zone(),
-                                NEW_OBJECT_WITH_LEN(PcDescriptors, length));
+  intptr_t offset = reader->Read<int32_t>();
+  PcDescriptors& result = PcDescriptors::ZoneHandle(reader->zone());
+  result ^= reader->GetObjectAt(offset);
   reader->AddBackRef(object_id, &result, kIsDeserialized);
 
-  if (result.Length() > 0) {
-    NoSafepointScope no_safepoint;
-    intptr_t len = result.Length();
-    uint8_t* data = result.UnsafeMutableNonPointer(result.raw_ptr()->data());
-    reader->ReadBytes(data, len);
-  }
-
   return result.raw();
 }
 
@@ -1671,12 +1669,8 @@ void RawPcDescriptors::WriteTo(SnapshotWriter* writer,
   writer->WriteInlinedObjectHeader(object_id);
   writer->WriteIndexedObject(kPcDescriptorsCid);
   writer->WriteTags(writer->GetObjectTags(this));
-  writer->Write<int32_t>(ptr()->length_);
-  if (ptr()->length_ > 0) {
-    intptr_t len = ptr()->length_;
-    uint8_t* data = reinterpret_cast<uint8_t*>(ptr()->data());
-    writer->WriteBytes(data, len);
-  }
+
+  writer->Write<int32_t>(writer->GetObjectId(this));
 }
 
 
@@ -1733,22 +1727,11 @@ RawStackmap* Stackmap::ReadFrom(SnapshotReader* reader,
   ASSERT(reader->snapshot_code());
   ASSERT(kind == Snapshot::kFull);
 
-  const int32_t length = reader->Read<int32_t>();
-  Stackmap& result =
-      Stackmap::ZoneHandle(reader->zone(),
-                           reader->NewStackmap(length));
+  intptr_t offset = reader->Read<int32_t>();
+  Stackmap& result = Stackmap::ZoneHandle(reader->zone());
+  result ^= reader->GetObjectAt(offset);
   reader->AddBackRef(object_id, &result, kIsDeserialized);
 
-  result.SetRegisterBitCount(reader->Read<int32_t>());
-  result.SetPcOffset(reader->Read<uint32_t>());
-
-  if (length > 0) {
-    NoSafepointScope no_safepoint;
-    intptr_t len = (result.Length() + 7) / 8;
-    uint8_t* data = result.UnsafeMutableNonPointer(result.raw_ptr()->data());
-    reader->ReadBytes(data, len);
-  }
-
   return result.raw();
 }
 
@@ -1765,14 +1748,7 @@ void RawStackmap::WriteTo(SnapshotWriter* writer,
   writer->WriteIndexedObject(kStackmapCid);
   writer->WriteTags(writer->GetObjectTags(this));
 
-  writer->Write<int32_t>(ptr()->length_);
-  writer->Write<int32_t>(ptr()->register_bit_count_);
-  writer->Write<uint32_t>(ptr()->pc_offset_);
-  if (ptr()->length_ > 0) {
-    intptr_t len = (ptr()->length_ + 7) / 8;
-    uint8_t* data = reinterpret_cast<uint8_t*>(ptr()->data());
-    writer->WriteBytes(data, len);
-  }
+  writer->Write<int32_t>(writer->GetObjectId(this));
 }
 
 
@@ -2572,6 +2548,14 @@ RawOneByteString* OneByteString::ReadFrom(SnapshotReader* reader,
                                           intptr_t tags,
                                           Snapshot::Kind kind,
                                           bool as_reference) {
+  if (reader->snapshot_code()) {
+    ASSERT(kind == Snapshot::kFull);
+    intptr_t offset = reader->Read<int32_t>();
+    String& result = String::ZoneHandle(reader->zone());
+    result ^= reader->GetObjectAt(offset);
+    reader->AddBackRef(object_id, &result, kIsDeserialized);
+    return raw(result);
+  }
   // Read the length so that we can determine instance size to allocate.
   ASSERT(reader != NULL);
   intptr_t len = reader->ReadSmiValue();
@@ -2679,6 +2663,22 @@ void RawOneByteString::WriteTo(SnapshotWriter* writer,
                                intptr_t object_id,
                                Snapshot::Kind kind,
                                bool as_reference) {
+  if (writer->snapshot_code()) {
+    ASSERT(writer->snapshot_code());
+    ASSERT(kind == Snapshot::kFull);
+    // Assert that hash is computed.
+    if (ptr()->hash_ == NULL) {
+      ptr()->hash_ = Smi::New(String::Hash(ptr()->data(),
+                                           Smi::Value(ptr()->length_)));
+    }
+    ASSERT(ptr()->hash_ != NULL);
+    // Write out the serialization header value for this object.
+    writer->WriteInlinedObjectHeader(object_id);
+    writer->WriteIndexedObject(kOneByteStringCid);
+    writer->WriteTags(writer->GetObjectTags(this));
+    writer->Write<int32_t>(writer->GetObjectId(this));
+    return;
+  }
   StringWriteTo(writer,
                 object_id,
                 kind,