[llvm-dev] MCJit and remove module memory leak?

[koffie drinker via llvm-dev]

Hi Lang,

I'm starting to migrate the MCJIT to ORC.
The ideal scenario for a jit would be to generate the code and release
module related objects.

I had this in mind:
- Add module to jit
- Generate code
- Remove module
- Retain memory section that was used to store the generated code.

Using this scenario, memory usage will be kept to a minimum. (I'm seeing
quite some mem usage with MCJIT, it allocates a lot of memory but only uses
small portion of it).
Do you have any pointers on how to  get this starting ? I'm willing to
share the results once it's finished. I might be useful to others as well.



On Thu, Nov 17, 2016 at 12:54 AM, Lang Hames <lhames at gmail.com> wrote:

> Hi Kevin, Koffie,
>
> We will start migrating to ORC for next release, but for now, this release
>> invoke delete after remove right?
>
>
> MCJIT's removeModule method does not delete the module. You'll need to do
> that manually. OrcMCJITReplacement is a bug-for-bug compatible
> implementation of MCJIT using ORC components, so it does not free the
> memory either.
>
> Does this mean MCJIT is dead/deprecated and projects using it should start
>> migrating away now? If so, what's the time frame?
>
>
> The short answer is yes: I expect MCJIT to be deprecated soon and
> eventually killed off. I'll be sending an email with details and a
> discussion of the timeline to the dev-list in the next few days. That will
> contain suggestions on how to transition to the new APIs (which I expect to
> be relatively painless for most people). I can CC you on it if that helps?
>
> Cheers,
> Lang.
>
>
> On Fri, Nov 11, 2016 at 12:00 AM, koffie drinker via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> There's a orc mcjit drop in replacement in the source tree.
>> Am I correct to assume that Orc is used (and emulating mcjit behaviour)
>> when replacing
>> LLVMLinkInOrcMCJITReplacement();
>> //LLVMLinkInMCJIT();
>> and linking with libOrcJit ?
>> Does this replacement handle memory better than original mcjit ?
>>
>>
>> On Mon, Nov 7, 2016 at 8:39 PM, Kevin P. Neal via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> On Fri, Nov 04, 2016 at 04:20:32PM -0700, Lang Hames via llvm-dev wrote:
>>> >    Hi Koffie,
>>> >    Kaleidoscope is no longer using MCJIT - it has been moved over to
>>> the
>>> >    ORC-based KaleidoscopeJIT class (see
>>> >    llvm/examples/Kaleidoscope/include/KaleidoscopeJIT.h). The
>>> removeModule
>>> >    method there does not leak memory.
>>> >    I've added documentation in r286026 to describe MCJIT removeModule's
>>> >    crazy ownership contract.
>>> >    This will be fixed properly when we kill off ExecutionEngine. :)
>>>
>>> Does this mean MCJIT is dead/deprecated and projects using it should
>>> start
>>> migrating away now? If so, what's the time frame?
>>>
>>> --
>>> Kevin P. Neal                                http://www.pobox.com/~kpn/
>>>
>>> "It sounded pretty good, but it's hard to tell how it will work out
>>> in practice." -- Dennis Ritchie, ~1977, "Summary of a DEC 32-bit machine"
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20161117/e78beaaa/attachment.html>