[Development] V4 porting

[Dmitriy -]

One more question:

qt-5.5.1/qtdeclarative/src/qml/jit/qv4assembler_p.h


    // V4 uses two stacks: one stack with QV4::Value items, which is
checked by the garbage

    // collector, and one stack used by the native C/C++/ABI code.
This C++ stack is not scanned

    // by the garbage collector, so if any JS object needs to be
retained, it should be put on the

    // JS stack.

    //

    // The "saved reg arg X" are on the C++ stack is used to store
values in registers that need to

    // be passed by reference to native functions. It is fine to use
the C++ stack, because only

    // non-object values can be stored in registers.

    //

    // Stack layout for the C++ stack:

    //   return address

    //   old FP                     <- FP

    //   callee saved reg n

    //   ...

    //   callee saved reg 0

    //   saved reg arg n

    //   ...

    //   saved reg arg 0            <- SP

    //

    // Stack layout for the JS stack:

    //   function call argument n   <- LocalsRegister

    //   ...

    //   function call argument 0

    //   local 0

    //   ...

    //   local n


// First save any arguments that reside in registers, because they
could be overwritten

// if that register is also used to pass arguments.

saveOutRegister<5>(arg6);

saveOutRegister<4>(arg5);

saveOutRegister<3>(arg4);

saveOutRegister<2>(arg3);

saveOutRegister<1>(arg2);

saveOutRegister<0>(arg1);

...


What kind of stack use for saving registers? Is it c++/ABI stack (I
hope) or Js stack?



On Thu, Dec 24, 2015 at 5:42 PM, Dmitriy - <dima00782 at gmail.com> wrote:

> Thank.
> I want to port JIT. Where should I start?
> You have any roadmap for this?
>
> Now I'm using qmljs tool for testing purpose.
> I has seen in qt-5.5.1/qtdeclarative/src/qml/jsruntime/qv4script.cpp:
>
> Script::parse():
>
> ...
>
> RuntimeCodegen cg(v4, strictMode);
>
> cg.generateFromProgram(sourceFile, sourceCode, program, &module, QQmlJS::Codegen::EvalCode, inheritedLocals);
>
> if (v4->hasException) return;
>
> QV4::Compiler::JSUnitGenerator jsGenerator(&module);
>
> QScopedPointer<EvalInstructionSelection> isel(...);
>
> ...
>
> QQmlRefPointer<QV4::CompiledData::CompilationUnit> compilationUnit = isel->compile();
>
> vmFunction = compilationUnit->linkToEngine(v4);
>
> ...
>
>
> Why do you compile script while parse it? Do you use AOT compiling?
>
>
> On Thu, Dec 24, 2015 at 5:18 PM, Hausmann Simon <
> Simon.Hausmann at theqtcompany.com> wrote:
>
>> Hi,
>>
>> Moth is the portable interpreter that will be used instead of the
>> just-in-time compiler if your platform doesn't support it. It should be
>> chosen automatically for you according to the #ifdefs in qv4global_p.h.
>>
>> So if you have qtbase compiling, then qml should also work. If you want
>> things to run faster, then you will have to port the JIT.
>>
>> Simon
>>
>> *From: *Dmitriy -
>> *Sent: *Thursday, December 24, 2015 10:47
>> *To: *development at qt-project.org
>> *Subject: *[Development] V4 porting
>>
>> Hi!
>> I want to port v4 engine to the new platform. The platform is Linux OS
>> and new processor. The processor looks like intel itanium. It is VLIW and
>> EPIC.
>> I have a c++/c compilers for the new architecture.
>>
>> I want to design qt quic qml application for the new platform. As a can
>> see in code, I need v4vm backend for this purpose.
>>
>> I'm see this:
>>
>> case use_moth: {
>>         QV4::EvalISelFactory* iSelFactory = 0;
>>         if (mode == use_moth) {
>>             iSelFactory = new QV4::Moth::ISelFactory;#ifdef V4_ENABLE_JIT
>>         } else {
>>             iSelFactory = new QV4::JIT::ISelFactory;#endif // V4_ENABLE_JIT
>>         }
>>
>>         QV4::ExecutionEngine vm(iSelFactory);
>>
>>         QV4::Scope scope(&vm);
>>         QV4::ScopedContext ctx(scope, vm.rootContext());
>>
>> As I understand v4vm has two backends - Moth and Masm.
>>
>> What is Moth?
>>
>> --
>> Regards,
>> Dmitry Bezheckov.
>>
>
>
>
> --
> Regards,
> Dmitry Bezheckov.
>



-- 
Regards,
Dmitry Bezheckov.
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