[VM] Introduction of type testing stubs - Part 1

This CL:

  * Adds a field to [RawAbstractType] which will always hold a pointer
    to the entrypoint of a type testing stub

  * Makes this new field be initialized to a default stub whenever a
    instances are created (e.g. via Type::New(), snapshot reader, ...)

  * Makes the clustered snapshotter write a reference to the
    corresponding [RawInstructions] object when writing the field and do
    the reverse when reading it.

  * Makes us call the type testing stub for performing assert-assignable
    checks.

To reduce unnecessary loads on callsites, we store the entrypoint of the
type testing stubs directly in the type objects.  This means that the
caller of type testing stubs can simply branch there without populating
a code object first.  This also means that the type testing stubs
themselves have no access to a pool and we therefore also don't hold on
to the [Code] object, only the [Instruction] object is necessary.

The type testing stubs do not setup a frame themselves and also have no
safepoint.  In the case when the type testing stubs could not determine
a positive answer they will tail-call a general-purpose stub.

The general-purpose stub sets up a stub frame, tries to consult a
[SubtypeTestCache] and bails out to runtime if this was unsuccessful.

This CL is just the the first, for ease of reviewing.  The actual
type-specialized type testing stubs will be generated in later CLs.

Issue dart-lang/sdk#31798

Change-Id: I174a11b3b812799f399a60af799144c2ba3c26ec
Reviewed-on: https://dart-review.googlesource.com/44787
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Régis Crelier <regis@google.com>

Author: mkustermann

runtime/vm/class_finalizer.cc

@@ -18,6 +18,7 @@
 #include "vm/symbols.h"
 #include "vm/timeline.h"
 #include "vm/type_table.h"
+#include "vm/type_testing_stubs.h"
 
 namespace dart {
 
@@ -589,6 +590,10 @@ void ClassFinalizer::ResolveType(const Class& cls, const AbstractType& type) {
       }
     }
   }
+
+  // After resolving, we re-initialize the type testing stub.
+  type.SetTypeTestingStub(
+      Instructions::Handle(TypeTestingStubGenerator::DefaultCodeForType(type)));
 }
 
 void ClassFinalizer::FinalizeTypeParameters(const Class& cls,

runtime/vm/clustered_snapshot.cc

@@ -3014,7 +3014,8 @@ class LibraryPrefixDeserializationCluster : public DeserializationCluster {
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class TypeSerializationCluster : public SerializationCluster {
  public:
-  TypeSerializationCluster() : SerializationCluster("Type") {}
+  explicit TypeSerializationCluster(const TypeTestingStubFinder& ttsf)
+      : SerializationCluster("Type"), type_testing_stubs_(ttsf) {}
   virtual ~TypeSerializationCluster() {}
 
   void Trace(Serializer* s, RawObject* object) {
@@ -3069,6 +3070,12 @@ class TypeSerializationCluster : public SerializationCluster {
       }
       s->WriteTokenPosition(type->ptr()->token_pos_);
       s->Write<int8_t>(type->ptr()->type_state_);
+      if (s->kind() == Snapshot::kFullAOT) {
+        RawInstructions* instr = type_testing_stubs_.LookupByAddresss(
+            type->ptr()->type_test_stub_entry_point_);
+        const int32_t text_offset = s->GetTextOffset(instr, Code::null());
+        s->Write<int32_t>(text_offset);
+      }
     }
     count = objects_.length();
     for (intptr_t i = 0; i < count; i++) {
@@ -3080,18 +3087,35 @@ class TypeSerializationCluster : public SerializationCluster {
       }
       s->WriteTokenPosition(type->ptr()->token_pos_);
       s->Write<int8_t>(type->ptr()->type_state_);
+      if (s->kind() == Snapshot::kFullAOT) {
+        RawInstructions* instr = type_testing_stubs_.LookupByAddresss(
+            type->ptr()->type_test_stub_entry_point_);
+        const int32_t text_offset = s->GetTextOffset(instr, Code::null());
+        s->Write<int32_t>(text_offset);
+      }
+    }
+
+    // The [Type::dynamic_type()] object is not serialized, so we manually send
+    // the type testing stub for it.
+    if (s->kind() == Snapshot::kFullAOT && s->for_vm_isolate()) {
+      RawInstructions* instr = type_testing_stubs_.LookupByAddresss(
+          Type::dynamic_type().type_test_stub_entry_point());
+      const int32_t text_offset = s->GetTextOffset(instr, Code::null());
+      s->Write<int32_t>(text_offset);
     }
   }
 
  private:
   GrowableArray<RawType*> canonical_objects_;
   GrowableArray<RawType*> objects_;
+  const TypeTestingStubFinder& type_testing_stubs_;
 };
 #endif  // !DART_PRECOMPILED_RUNTIME
 
 class TypeDeserializationCluster : public DeserializationCluster {
  public:
-  TypeDeserializationCluster() {}
+  TypeDeserializationCluster()
+      : type_(AbstractType::Handle()), instr_(Instructions::Handle()) {}
   virtual ~TypeDeserializationCluster() {}
 
   void ReadAlloc(Deserializer* d) {
@@ -3126,6 +3150,12 @@ class TypeDeserializationCluster : public DeserializationCluster {
       }
       type->ptr()->token_pos_ = d->ReadTokenPosition();
       type->ptr()->type_state_ = d->Read<int8_t>();
+      if (d->kind() == Snapshot::kFullAOT) {
+        const int32_t text_offset = d->Read<int32_t>();
+        instr_ = d->GetInstructionsAt(text_offset);
+        type_ = type;
+        type_.SetTypeTestingStub(instr_);
+      }
     }
 
     for (intptr_t id = start_index_; id < stop_index_; id++) {
@@ -3139,18 +3169,53 @@ class TypeDeserializationCluster : public DeserializationCluster {
       }
       type->ptr()->token_pos_ = d->ReadTokenPosition();
       type->ptr()->type_state_ = d->Read<int8_t>();
+      if (d->kind() == Snapshot::kFullAOT) {
+        const int32_t text_offset = d->Read<int32_t>();
+        instr_ = d->GetInstructionsAt(text_offset);
+        type_ = type;
+        type_.SetTypeTestingStub(instr_);
+      }
+    }
+
+    // The [Type::dynamic_type()] object is not serialized, so we manually send
+    // the type testing stub for it.
+    if (d->kind() == Snapshot::kFullAOT && d->for_vm_isolate()) {
+      const int32_t text_offset = d->Read<int32_t>();
+      Dart::vm_isolate()->heap()->WriteProtect(false);
+      instr_ = d->GetInstructionsAt(text_offset);
+      Type::dynamic_type().SetTypeTestingStub(instr_);
+      Dart::vm_isolate()->heap()->WriteProtect(true);
+    }
+  }
+
+  void PostLoad(const Array& refs, Snapshot::Kind kind, Zone* zone) {
+    if (kind != Snapshot::kFullAOT) {
+      for (intptr_t id = canonical_start_index_; id < canonical_stop_index_;
+           id++) {
+        type_ ^= refs.At(id);
+        instr_ = TypeTestingStubGenerator::DefaultCodeForType(type_);
+        type_.SetTypeTestingStub(instr_);
+      }
+      for (intptr_t id = start_index_; id < stop_index_; id++) {
+        type_ ^= refs.At(id);
+        instr_ = TypeTestingStubGenerator::DefaultCodeForType(type_);
+        type_.SetTypeTestingStub(instr_);
+      }
     }
   }
 
  private:
   intptr_t canonical_start_index_;
   intptr_t canonical_stop_index_;
+  AbstractType& type_;
+  Instructions& instr_;
 };
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class TypeRefSerializationCluster : public SerializationCluster {
  public:
-  TypeRefSerializationCluster() : SerializationCluster("TypeRef") {}
+  explicit TypeRefSerializationCluster(const TypeTestingStubFinder& ttsf)
+      : SerializationCluster("TypeRef"), type_testing_stubs_(ttsf) {}
   virtual ~TypeRefSerializationCluster() {}
 
   void Trace(Serializer* s, RawObject* object) {
@@ -3183,17 +3248,25 @@ class TypeRefSerializationCluster : public SerializationCluster {
       for (RawObject** p = from; p <= to; p++) {
         s->WriteRef(*p);
       }
+      if (s->kind() == Snapshot::kFullAOT) {
+        RawInstructions* instr = type_testing_stubs_.LookupByAddresss(
+            type->ptr()->type_test_stub_entry_point_);
+        const int32_t text_offset = s->GetTextOffset(instr, Code::null());
+        s->Write<int32_t>(text_offset);
+      }
     }
   }
 
  private:
   GrowableArray<RawTypeRef*> objects_;
+  const TypeTestingStubFinder& type_testing_stubs_;
 };
 #endif  // !DART_PRECOMPILED_RUNTIME
 
 class TypeRefDeserializationCluster : public DeserializationCluster {
  public:
-  TypeRefDeserializationCluster() {}
+  TypeRefDeserializationCluster()
+      : type_(AbstractType::Handle()), instr_(Instructions::Handle()) {}
   virtual ~TypeRefDeserializationCluster() {}
 
   void ReadAlloc(Deserializer* d) {
@@ -3218,14 +3291,26 @@ class TypeRefDeserializationCluster : public DeserializationCluster {
       for (RawObject** p = from; p <= to; p++) {
         *p = d->ReadRef();
       }
+      if (d->kind() == Snapshot::kFullAOT) {
+        const int32_t text_offset = d->Read<int32_t>();
+        instr_ = d->GetInstructionsAt(text_offset);
+        type_ = type;
+        type_.SetTypeTestingStub(instr_);
+      }
     }
   }
+
+ private:
+  AbstractType& type_;
+  Instructions& instr_;
 };
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class TypeParameterSerializationCluster : public SerializationCluster {
  public:
-  TypeParameterSerializationCluster() : SerializationCluster("TypeParameter") {}
+  explicit TypeParameterSerializationCluster(const TypeTestingStubFinder& ttsf)
+      : SerializationCluster("TypeParameter"), type_testing_stubs_(ttsf) {}
+
   virtual ~TypeParameterSerializationCluster() {}
 
   void Trace(Serializer* s, RawObject* object) {
@@ -3263,17 +3348,25 @@ class TypeParameterSerializationCluster : public SerializationCluster {
       s->WriteTokenPosition(type->ptr()->token_pos_);
       s->Write<int16_t>(type->ptr()->index_);
       s->Write<int8_t>(type->ptr()->type_state_);
+      if (s->kind() == Snapshot::kFullAOT) {
+        RawInstructions* instr = type_testing_stubs_.LookupByAddresss(
+            type->ptr()->type_test_stub_entry_point_);
+        const int32_t text_offset = s->GetTextOffset(instr, Code::null());
+        s->Write<int32_t>(text_offset);
+      }
     }
   }
 
  private:
   GrowableArray<RawTypeParameter*> objects_;
+  const TypeTestingStubFinder& type_testing_stubs_;
 };
 #endif  // !DART_PRECOMPILED_RUNTIME
 
 class TypeParameterDeserializationCluster : public DeserializationCluster {
  public:
-  TypeParameterDeserializationCluster() {}
+  TypeParameterDeserializationCluster()
+      : type_(AbstractType::Handle()), instr_(Instructions::Handle()) {}
   virtual ~TypeParameterDeserializationCluster() {}
 
   void ReadAlloc(Deserializer* d) {
@@ -3303,8 +3396,28 @@ class TypeParameterDeserializationCluster : public DeserializationCluster {
       type->ptr()->token_pos_ = d->ReadTokenPosition();
       type->ptr()->index_ = d->Read<int16_t>();
       type->ptr()->type_state_ = d->Read<int8_t>();
+      if (d->kind() == Snapshot::kFullAOT) {
+        const int32_t text_offset = d->Read<int32_t>();
+        instr_ = d->GetInstructionsAt(text_offset);
+        type_ = type;
+        type_.SetTypeTestingStub(instr_);
+      }
+    }
+  }
+
+  void PostLoad(const Array& refs, Snapshot::Kind kind, Zone* zone) {
+    if (kind != Snapshot::kFullAOT) {
+      for (intptr_t id = start_index_; id < stop_index_; id++) {
+        type_ ^= refs.At(id);
+        instr_ = TypeTestingStubGenerator::DefaultCodeForType(type_);
+        type_.SetTypeTestingStub(instr_);
+      }
     }
   }
+
+ private:
+  AbstractType& type_;
+  Instructions& instr_;
 };
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
@@ -4556,7 +4669,8 @@ Serializer::Serializer(Thread* thread,
                        uint8_t** buffer,
                        ReAlloc alloc,
                        intptr_t initial_size,
-                       ImageWriter* image_writer)
+                       ImageWriter* image_writer,
+                       bool vm_isolate)
     : StackResource(thread),
       heap_(thread->isolate()->heap()),
       zone_(thread->zone()),
@@ -4568,7 +4682,8 @@ Serializer::Serializer(Thread* thread,
       num_cids_(0),
       num_base_objects_(0),
       num_written_objects_(0),
-      next_ref_index_(1)
+      next_ref_index_(1),
+      vm_isolate_(vm_isolate)
 #if defined(SNAPSHOT_BACKTRACE)
       ,
       current_parent_(Object::null()),
@@ -4668,11 +4783,11 @@ SerializationCluster* Serializer::NewClusterForClass(intptr_t cid) {
     case kLibraryPrefixCid:
       return new (Z) LibraryPrefixSerializationCluster();
     case kTypeCid:
-      return new (Z) TypeSerializationCluster();
+      return new (Z) TypeSerializationCluster(type_testing_stubs_);
     case kTypeRefCid:
-      return new (Z) TypeRefSerializationCluster();
+      return new (Z) TypeRefSerializationCluster(type_testing_stubs_);
     case kTypeParameterCid:
-      return new (Z) TypeParameterSerializationCluster();
+      return new (Z) TypeParameterSerializationCluster(type_testing_stubs_);
     case kBoundedTypeCid:
       return new (Z) BoundedTypeSerializationCluster();
     case kClosureCid:
@@ -5120,7 +5235,8 @@ Deserializer::Deserializer(Thread* thread,
                            const uint8_t* buffer,
                            intptr_t size,
                            const uint8_t* instructions_buffer,
-                           const uint8_t* data_buffer)
+                           const uint8_t* data_buffer,
+                           bool vm_isolate)
     : StackResource(thread),
       heap_(thread->isolate()->heap()),
       zone_(thread->zone()),
@@ -5129,7 +5245,8 @@ Deserializer::Deserializer(Thread* thread,
       image_reader_(NULL),
       refs_(NULL),
       next_ref_index_(1),
-      clusters_(NULL) {
+      clusters_(NULL),
+      vm_isolate_(vm_isolate) {
   if (Snapshot::IncludesCode(kind)) {
     ASSERT(instructions_buffer != NULL);
     ASSERT(data_buffer != NULL);
@@ -5716,7 +5833,8 @@ intptr_t FullSnapshotWriter::WriteVMSnapshot() {
 
   ASSERT(vm_snapshot_data_buffer_ != NULL);
   Serializer serializer(thread(), kind_, vm_snapshot_data_buffer_, alloc_,
-                        kInitialSize, vm_image_writer_);
+                        kInitialSize, vm_image_writer_,
+                        /*vm_isolate=*/true);
 
   serializer.ReserveHeader();
   serializer.WriteVersionAndFeatures(true);
@@ -5746,7 +5864,8 @@ void FullSnapshotWriter::WriteIsolateSnapshot(intptr_t num_base_objects) {
       thread(), Timeline::GetIsolateStream(), "WriteIsolateSnapshot"));
 
   Serializer serializer(thread(), kind_, isolate_snapshot_data_buffer_, alloc_,
-                        kInitialSize, isolate_image_writer_);
+                        kInitialSize, isolate_image_writer_,
+                        /*vm_isolate=*/false);
   ObjectStore* object_store = isolate()->object_store();
   ASSERT(object_store != NULL);
 
@@ -5816,7 +5935,8 @@ FullSnapshotReader::FullSnapshotReader(const Snapshot* snapshot,
 
 RawApiError* FullSnapshotReader::ReadVMSnapshot() {
   Deserializer deserializer(thread_, kind_, buffer_, size_,
-                            instructions_buffer_, data_buffer_);
+                            instructions_buffer_, data_buffer_,
+                            /*vm_isolate=*/true);
 
   RawApiError* error = deserializer.VerifyVersionAndFeatures(/*isolate=*/NULL);
   if (error != ApiError::null()) {
@@ -5840,7 +5960,8 @@ RawApiError* FullSnapshotReader::ReadVMSnapshot() {
 
 RawApiError* FullSnapshotReader::ReadIsolateSnapshot() {
   Deserializer deserializer(thread_, kind_, buffer_, size_,
-                            instructions_buffer_, data_buffer_);
+                            instructions_buffer_, data_buffer_,
+                            /*vm_isolate=*/false);
 
   RawApiError* error =
       deserializer.VerifyVersionAndFeatures(thread_->isolate());