[ignition] Create the type feedback vector after bytecode generation

src/interpreter/bytecode-generator.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/builtins/builtins-constructor.h"
 #include "src/code-stubs.h"
@@ skipping 633 matching lines @@
     }
   }
 
   // Build array literal constant elements
   for (std::pair<ArrayLiteral*, size_t> literal : array_literals_) {
     ArrayLiteral* array_literal = literal.first;
     Handle<ConstantElementsPair> constant_elements =
         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(

[Michael Starzinger, 2017/01/16 15:28:41]

Some follow-up questions:
1) Would it be possible to do this in FinalizeUnoptimizedCompilationJob instead?
2) And more importantly could we keep it in sync with FCG and also allocate it
just before unoptimized code is installed for FullCodegenCompilationJob?

[Leszek Swirski, 2017/01/16 16:28:03]

I'm hesitant, could this interact badly with --always-opt?

+      info()->isolate(), info()->shared_info(),
+      info()->literal()->feedback_vector_spec());
 }
 
 void BytecodeGenerator::GenerateBytecode(uintptr_t stack_limit) {
   DisallowHeapAllocation no_allocation;
   DisallowHandleAllocation no_handles;
   DisallowHandleDereference no_deref;
 
   InitializeAstVisitor(stack_limit);
 
   // Initialize the incoming context.
@@ skipping 2685 matching lines @@
 }
 
 Runtime::FunctionId BytecodeGenerator::StoreKeyedToSuperRuntimeId() {
   return is_strict(language_mode()) ? Runtime::kStoreKeyedToSuper_Strict
                                     : Runtime::kStoreKeyedToSuper_Sloppy;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8