More precompiled snapshotting.

runtime/vm/dart.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/dart.h"
 
 #include "vm/code_observers.h"
 #include "vm/cpu.h"
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
@@ skipping 101 matching lines @@
   predefined_handles_ = new ReadOnlyHandles();
   // Create the VM isolate and finish the VM initialization.
   ASSERT(thread_pool_ == NULL);
   thread_pool_ = new ThreadPool();
   {
     Thread* T = Thread::Current();
     ASSERT(T != NULL);
     ASSERT(vm_isolate_ == NULL);
     ASSERT(Flags::Initialized());
     const bool is_vm_isolate = true;
+    const bool precompiled = instructions_snapshot != NULL;
 
     // Setup default flags for the VM isolate.
     Isolate::Flags vm_flags;
     Dart_IsolateFlags api_flags;
     vm_flags.CopyTo(&api_flags);
     vm_isolate_ = Isolate::Init("vm-isolate", api_flags, is_vm_isolate);
+    vm_isolate_->set_compilation_allowed(!precompiled);
     // Verify assumptions about executing in the VM isolate.
     ASSERT(vm_isolate_ == Isolate::Current());
     ASSERT(vm_isolate_ == Thread::Current()->isolate());
 
     StackZone zone(T);
     HandleScope handle_scope(T);
     Object::InitNull(vm_isolate_);
     ObjectStore::Init(vm_isolate_);
     TargetCPUFeatures::InitOnce();
     Object::InitOnce(vm_isolate_);
     ArgumentsDescriptor::InitOnce();
-    StubCode::InitOnce();
-    Thread::InitOnceAfterObjectAndStubCode();
-    // Now that the needed stub has been generated, set the stack limit.
-    vm_isolate_->InitializeStackLimit();
+    if (precompiled) {
+      // Stub code loaded from snapshot.
+    } else {
+      StubCode::InitOnce();
+    }

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

Would read better as:

// When precompiling the stub code is initialized from the snapshot.
if (!precompiled) {
  StubCode::InitOnce();
}

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

Done.

     if (vm_isolate_snapshot != NULL) {
       const Snapshot* snapshot = Snapshot::SetupFromBuffer(vm_isolate_snapshot);
       if (snapshot == NULL) {
         return "Invalid vm isolate snapshot seen.";
       }
       ASSERT(snapshot->kind() == Snapshot::kFull);
       VmIsolateSnapshotReader reader(snapshot->content(),
                                      snapshot->length(),
                                      instructions_snapshot,
                                      T);
       const Error& error = Error::Handle(reader.ReadVmIsolateSnapshot());
       if (!error.IsNull()) {
         return error.ToCString();
       }
       if (FLAG_trace_isolates) {
         OS::Print("Size of vm isolate snapshot = %" Pd "\n",
                   snapshot->length());
         vm_isolate_->heap()->PrintSizes();
         vm_isolate_->megamorphic_cache_table()->PrintSizes();
         intptr_t size;
         intptr_t capacity;
         Symbols::GetStats(vm_isolate_, &size, &capacity);
         OS::Print("VM Isolate: Number of symbols : %" Pd "\n", size);
         OS::Print("VM Isolate: Symbol table capacity : %" Pd "\n", capacity);
       }
     } else {
       Symbols::InitOnce(vm_isolate_);

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

Maybe the if (!precompiled) check from above should go here, isn;t it true that
if precompiling (vm_isolate_snapshot != NULL) should be true.

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

Yes, precompiled implies there is a vm isolate snapshot.

     }
+    Thread::InitOnceAfterObjectAndStubCode();
+    // Now that the needed stub has been generated, set the stack limit.
+    vm_isolate_->InitializeStackLimit();
     Scanner::InitOnce();
 #if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
     // Dart VM requires at least SSE2.
     if (!TargetCPUFeatures::sse2_supported()) {
       return "SSE2 is required.";
     }
 #endif
     Object::FinalizeVMIsolate(vm_isolate_);
 #if defined(DEBUG)
     vm_isolate_->heap()->Verify(kRequireMarked);
@@ skipping 200 matching lines @@
   return predefined_handles_->handles_.IsValidScopedHandle(address);
 }
 
 
 bool Dart::IsReadOnlyApiHandle(Dart_Handle handle) {
   ASSERT(predefined_handles_ != NULL);
   return predefined_handles_->api_handles_.IsValidHandle(handle);
 }
 
 }  // namespace dart