[ignition] Create the type feedback vector after bytecode generation

BUG=v8:5832

Review-Url: https://codereview.chromium.org/2627783008
Cr-Commit-Position: refs/heads/master@{#42377}

src/compiler.cc

@@ -292,24 +292,9 @@ void RecordFunctionCompilation(CodeEventListener::LogEventsAndTags tag,
 
 void EnsureFeedbackMetadata(CompilationInfo* info) {
   DCHECK(info->has_shared_info());
-
-  // If no type feedback metadata exists, we create it now. At this point the
-  // AstNumbering pass has already run. Note the snapshot can contain outdated
-  // vectors for a different configuration, hence we also recreate a new vector
-  // when the function is not compiled (i.e. no code was serialized).
-
-  // TODO(mvstanton): reintroduce is_empty() predicate to feedback_metadata().
-  if (info->shared_info()->feedback_metadata()->length() == 0 ||
-      !info->shared_info()->is_compiled()) {
-    Handle<TypeFeedbackMetadata> feedback_metadata = TypeFeedbackMetadata::New(
-        info->isolate(), info->literal()->feedback_vector_spec());
-    info->shared_info()->set_feedback_metadata(*feedback_metadata);
-  }
-
-  // It's very important that recompiles do not alter the structure of the type
-  // feedback vector. Verify that the structure fits the function literal.
-  CHECK(!info->shared_info()->feedback_metadata()->SpecDiffersFrom(
-      info->literal()->feedback_vector_spec()));
+  TypeFeedbackMetadata::EnsureAllocated(
+      info->isolate(), info->shared_info(),
+      info->literal()->feedback_vector_spec());
 }
 
 bool UseTurboFan(Handle<SharedFunctionInfo> shared) {
@@ -381,10 +366,11 @@ CompilationJob* GetUnoptimizedCompilationJob(CompilationInfo* info) {
   DCHECK_NOT_NULL(info->literal());
   DCHECK_NOT_NULL(info->scope());
 
-  EnsureFeedbackMetadata(info);
   if (ShouldUseIgnition(info)) {
+    // The bytecode generator will take care of feedback metadata creation.
     return interpreter::Interpreter::NewCompilationJob(info);
   } else {
+    EnsureFeedbackMetadata(info);
     return FullCodeGenerator::NewCompilationJob(info);
   }
 }

src/interpreter/bytecode-generator.cc

@@ -651,6 +651,14 @@ void BytecodeGenerator::AllocateDeferredConstants(Isolate* isolate) {
         array_literal->GetOrBuildConstantElements(isolate);
     builder()->InsertConstantPoolEntryAt(literal.second, constant_elements);
   }
+
+  // TODO(leszeks): ideally there would be no path to here where feedback
+  // metadata is previously created, and we could create it unconditionally.
+  // We should investigate again once FCG has shuffled off its mortal coil.
+  DCHECK(info()->has_shared_info());
+  TypeFeedbackMetadata::EnsureAllocated(
+      info()->isolate(), info()->shared_info(),
+      info()->literal()->feedback_vector_spec());
 }
 
 void BytecodeGenerator::GenerateBytecode(uintptr_t stack_limit) {

src/type-feedback-vector.cc

@@ -118,6 +118,26 @@ Handle<TypeFeedbackMetadata> TypeFeedbackMetadata::New(Isolate* isolate,
   return metadata;
 }
 
+// static
+void TypeFeedbackMetadata::EnsureAllocated(Isolate* isolate,
+                                           Handle<SharedFunctionInfo> sfi,
+                                           const FeedbackVectorSpec* spec) {
+  // If no type feedback metadata exists, create it. At this point the
+  // AstNumbering pass has already run. Note the snapshot can contain outdated
+  // vectors for a different configuration, hence we also recreate a new vector
+  // when the function is not compiled (i.e. no code was serialized).
+
+  // TODO(mvstanton): reintroduce is_empty() predicate to feedback_metadata().
+  if (sfi->feedback_metadata()->length() == 0 || !sfi->is_compiled()) {
+    Handle<TypeFeedbackMetadata> feedback_metadata =
+        TypeFeedbackMetadata::New(isolate, spec);
+    sfi->set_feedback_metadata(*feedback_metadata);
+  }
+
+  // It's very important that recompiles do not alter the structure of the type
+  // feedback vector. Verify that the structure fits the function literal.
+  CHECK(!sfi->feedback_metadata()->SpecDiffersFrom(spec));
+}
 
 bool TypeFeedbackMetadata::SpecDiffersFrom(
     const FeedbackVectorSpec* other_spec) const {

src/type-feedback-vector.h

@@ -217,6 +217,11 @@ class TypeFeedbackMetadata : public FixedArray {
   template <typename Spec>
   static Handle<TypeFeedbackMetadata> New(Isolate* isolate, const Spec* spec);
 
+  // Ensure that the given shared function info has type feedback metadata with
+  // the given spec.
+  static void EnsureAllocated(Isolate* isolate, Handle<SharedFunctionInfo> sfi,
+                              const FeedbackVectorSpec* spec);
+
 #ifdef OBJECT_PRINT
   // For gdb debugging.
   void Print();