Re: [chromium-dev] How can i hook object creation in ignition interpreter?

[Jakob Kummerow]

[+v8-users, chromium-dev to BCC]

There is no single bottleneck for JS object allocation; objects are created all over the place. As a starting point, you can look at all CodeStubAssembler::AllocateJS* and Factory::NewJS* functions. I don't know whether that set spans all JS object allocations, but at least it covers a fair bunch of them. Turbofan is a separate story, but I assume you're turning that off for your experiment.

On Mon, Sep 9, 2019 at 6:27 PM L TY <n0b0...@gmail.com> wrote:

Hello guys, I'm trying to do taint analysis in v8 with its ignition interpreter. I want to be noticed whenever a JS object is allocated. However, I cannot find the object allocation code in the interpreter.

Currently I have located the v8 bytecode generating process such as the code following:

void BytecodeGenerator::VisitDeclarations(Declaration::List* declarations) {
  RegisterAllocationScope register_scope(this);
  DCHECK(globals_builder()->empty());
  for (Declaration* decl : *declarations) {
    RegisterAllocationScope register_scope(this);
    Visit(decl);
  }
  if (globals_builder()->empty()) return;

  globals_builder()->set_constant_pool_entry(
      builder()->AllocateDeferredConstantPoolEntry());
  int encoded_flags = DeclareGlobalsEvalFlag::encode(info()->is_eval());

  // Emit code to declare globals.
  RegisterList args = register_allocator()->NewRegisterList(3);
  builder()
      ->LoadConstantPoolEntry(globals_builder()->constant_pool_entry())
      .StoreAccumulatorInRegister(args[0])
      .LoadLiteral(Smi::FromInt(encoded_flags))
      .StoreAccumulatorInRegister(args[1])
      .MoveRegister(Register::function_closure(), args[2])
      .CallRuntime(Runtime::kDeclareGlobals, args);

  // Push and reset globals builder.
  global_declarations_.push_back(globals_builder());
  globals_builder_ = new (zone()) GlobalDeclarationsBuilder(zone());
}

But I cannot find the object allocation process. Can you guys give me some advice about it?