Insert Special Code Sequence After Object allocation

[Xin Tong]

On Wed, Nov 28, 2012 at 12:58 AM, Xin Tong <xerox.time.tech at gmail.com> wrote:
> On Tue, Nov 27, 2012 at 11:23 PM, Krystal Mo <krystal.mo at oracle.com> wrote:
>> Hi Xin,
>>
>> Depends on what the code sequence is and what it does.
>>
>> If the code sequence you're inserting can be represented in C2's IR nodes,
>> then you can try to add those nodes in either
>> PhaseMacroExpand::expand_allocate_common() or
>> PhaseMacroExpand::initialize_object(), or somewhere else around.
>>
>
> It is a few assembly instructions. can i wrap the assemblies in a
> function that hasa prologue and epilogue to save everything. and does
> the IR has any way of calling a function ?
>
> Xin

Or another thing i am willing to do is to force the JIT to always fail
on the inlined allocation and force it to the out-of-line ( VM
managed) allocation. I just do not want to turn the JIT completely off
as that have an big impact on the behaviours of the program.  Is this
doable ?

Xin

>
>> If your code sequence cannot be represented in C2's IR, well, that will take
>> some effort. The AllocateNode is lost after PhaseMacroExpand, so you can't
>> use it as a mark to insert your code. You might want to use prefetchAlloc in
>> the AD files as a place to insert code, if that works for your purpose.
>>
>> That said, though, if the code sequence could be written in Java bytecode,
>> that'll be the easiest solution: don't have to touch the VM, just do
>> bytecode instrumentation.
>>
>> - Kris
>>
>>
>> On 2012/11/28 10:36, Xin Tong wrote:
>>>
>>> I would like to insert a special binary code sequence after the
>>> allocation of a java object in the opto JIT code. can anyone tell me
>>> how to do that ?
>>>
>>> Xin