[vm,dyn_modules] Initial support for hot reloading bytecode

TEST=ci

Change-Id: I879ff1c085ee06dda7836d01e2018d93e075f132
Cq-Include-Trybots: luci.dart.try:vm-aot-dyn-linux-debug-x64-try,vm-aot-dyn-linux-product-x64-try,vm-dyn-linux-debug-x64-try,vm-reload-linux-debug-x64-try,vm-reload-linux-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/439803
Reviewed-by: Slava Egorov <[email protected]>
Commit-Queue: Alexander Markov <[email protected]>

Author: alexmarkov

pkg/dart2bytecode/bin/kernel_service.dart

@@ -29,9 +29,11 @@ Uint8List _generateBytecode(
       hierarchy: hierarchy,
       target: target,
       options: BytecodeOptions(
-          enableAsserts: enableAsserts,
-          emitSourcePositions: true,
-          emitLocalVarInfo: true));
+        enableAsserts: enableAsserts,
+        emitSourcePositions: true,
+        emitLocalVarInfo: true,
+        emitInstanceFieldInitializers: true,
+      ));
   return byteSink.builder.takeBytes();
 }
 

runtime/vm/bytecode_reader.cc

@@ -84,8 +84,10 @@ BytecodeLoader::~BytecodeLoader() {
 FunctionPtr BytecodeLoader::LoadBytecode() {
   ASSERT(IsolateGroup::Current()->program_lock()->IsCurrentThreadWriter());
 
-  BytecodeReaderHelper component_reader(thread_, binary_);
-  bytecode_component_array_ = component_reader.ReadBytecodeComponent();
+  if (bytecode_component_array_.IsNull()) {
+    BytecodeReaderHelper component_reader(thread_, binary_);
+    bytecode_component_array_ = component_reader.ReadBytecodeComponent();
+  }
 
   BytecodeComponentData bytecode_component(bytecode_component_array_);
   BytecodeReaderHelper bytecode_reader(thread_, &bytecode_component);
@@ -108,7 +110,7 @@ void BytecodeLoader::SetOffset(const Object& obj, intptr_t offset) {
   bytecode_offsets_map_ = map.Release().ptr();
 }
 
-intptr_t BytecodeLoader::GetOffset(const Object& obj) {
+intptr_t BytecodeLoader::GetOffset(const Object& obj) const {
   BytecodeOffsetsMap map(bytecode_offsets_map_.ptr());
   const auto value = map.GetOrNull(obj);
   ASSERT(value != Object::null());
@@ -117,6 +119,41 @@ intptr_t BytecodeLoader::GetOffset(const Object& obj) {
   return offset;
 }
 
+bool BytecodeLoader::HasOffset(const Object& obj) const {
+  BytecodeOffsetsMap map(bytecode_offsets_map_.ptr());
+  const auto value = map.GetOrNull(obj);
+  ASSERT(map.Release().ptr() == bytecode_offsets_map_.ptr());
+  return value != Object::null();
+}
+
+void BytecodeLoader::FindModifiedLibraries(BitVector* modified_libs,
+                                           intptr_t* p_num_libraries,
+                                           intptr_t* p_num_classes,
+                                           intptr_t* p_num_procedures) {
+  if (bytecode_component_array_.IsNull()) {
+    BytecodeReaderHelper component_reader(thread_, binary_);
+    bytecode_component_array_ = component_reader.ReadBytecodeComponent();
+  }
+
+  BytecodeComponentData bytecode_component(bytecode_component_array_);
+  BytecodeReaderHelper bytecode_reader(thread_, &bytecode_component);
+  AlternativeReadingScope alt(&bytecode_reader.reader(),
+                              bytecode_component.GetLibraryIndexOffset());
+
+  bytecode_reader.FindModifiedLibraries(modified_libs,
+                                        bytecode_component.GetNumLibraries());
+
+  if (p_num_libraries != nullptr) {
+    *p_num_libraries = bytecode_component.GetNumLibraries();
+  }
+  if (p_num_classes != nullptr) {
+    *p_num_classes = bytecode_component.GetNumClasses();
+  }
+  if (p_num_procedures != nullptr) {
+    *p_num_procedures = bytecode_component.GetNumCodes();
+  }
+}
+
 BytecodeReaderHelper::BytecodeReaderHelper(Thread* thread,
                                            const TypedDataBase& typed_data)
     : reader_(typed_data),
@@ -755,8 +792,6 @@ void BytecodeReaderHelper::ReadLocalVariables(const Bytecode& bytecode,
 }
 
 ArrayPtr BytecodeReaderHelper::ReadBytecodeComponent() {
-  ASSERT(IsolateGroup::Current()->program_lock()->IsCurrentThreadWriter());
-
   AlternativeReadingScope alt(&reader_, 0);
 
   const intptr_t start_offset = reader_.offset();
@@ -1779,7 +1814,7 @@ void BytecodeReaderHelper::ReadFieldDeclarations(const Class& cls,
                        /* is_reflectable = */ false,
                        /* is_late = */ false, cls, Object::dynamic_type(),
                        TokenPosition::kNoSource, TokenPosition::kNoSource);
-
+    IG->RegisterStaticField(field, Object::null_object());
     fields.SetAt(num_fields, field);
   }
 
@@ -2284,17 +2319,35 @@ void BytecodeReaderHelper::ReadLibraryDeclarations(intptr_t num_libraries) {
     members = cls.fields();
     for (intptr_t j = 0, m = members.Length(); j < m; ++j) {
       field ^= members.At(j);
-      if ((field.is_static() || field.is_late()) &&
-          field.has_nontrivial_initializer()) {
-        function = field.EnsureInitializerFunction();
-        if (!function.HasBytecode()) {
-          ReadCode(function, thread_->bytecode_loader()->GetOffset(field));
+      if (field.has_nontrivial_initializer()) {
+        if (field.is_static() || field.is_late() ||
+            thread_->bytecode_loader()->HasOffset(field)) {
+          function = field.EnsureInitializerFunction();
+          if (!function.HasBytecode()) {
+            ReadCode(function, thread_->bytecode_loader()->GetOffset(field));
+          }
         }
       }
     }
   }
 }
 
+void BytecodeReaderHelper::FindModifiedLibraries(BitVector* modified_libs,
+                                                 intptr_t num_libraries) {
+  auto& uri = String::Handle(Z);
+  auto& lib = Library::Handle(Z);
+  for (intptr_t i = 0; i < num_libraries; ++i) {
+    uri ^= ReadObject();
+    reader_.ReadUInt();  // Skip offset.
+
+    lib = Library::LookupLibrary(thread_, uri);
+    if (!lib.IsNull() && !lib.is_dart_scheme()) {
+      // This is a library that already exists so mark it as being modified.
+      modified_libs->Add(lib.index());
+    }
+  }
+}
+
 void BytecodeReaderHelper::ReadParameterCovariance(
     const Function& function,
     intptr_t code_offset,

runtime/vm/bytecode_reader.h

@@ -31,7 +31,13 @@ class BytecodeLoader {
   }
 
   void SetOffset(const Object& obj, intptr_t offset);
-  intptr_t GetOffset(const Object& obj);
+  intptr_t GetOffset(const Object& obj) const;
+  bool HasOffset(const Object& obj) const;
+
+  void FindModifiedLibraries(BitVector* modified_libs,
+                             intptr_t* p_num_libraries,
+                             intptr_t* p_num_classes,
+                             intptr_t* p_num_procedures);
 
  private:
   Thread* thread_;
@@ -204,6 +210,7 @@ class BytecodeReaderHelper : public ValueObject {
   void ReadLibraryDeclaration(const Library& library,
                               const GrowableObjectArray& pending_classes);
   void ReadLibraryDeclarations(intptr_t num_libraries);
+  void FindModifiedLibraries(BitVector* modified_libs, intptr_t num_libraries);
 
   LibraryPtr ReadMain();