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

Lang Hames via llvm-dev
Wed, 16 Nov 2016 23:54:53 -0000

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
>>
>
>
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