[llvm-dev] JIT-Client for Shared Memory

[David Blaikie via llvm-dev]

And then I used reply instead of reply-all... I'm on a roll. Added llvm-dev
back again... So maybe this is right now. Maybe - sorry for the confusion

On Wed, Nov 7, 2018, 11:11 PM David Blaikie <dblaikie at gmail.com wrote:

> Well I meant to add him but failed. Cc'd him here now :)
>
> On Wed, Nov 7, 2018, 10:41 PM Gaier, Bjoern <Bjoern.Gaier at horiba.com
> wrote:
>
>> Is… Lang now added? I’m not sure about this system…
>>
>> My problem is that I can not change the size of the shared memory I’m
>> targeting – so I can only allocate it once, but how do I know how much
>> memory I’m going to need, when each sections requests the memory after each
>> other?
>> To work around this I first allocate the memory locally and count the
>> bytes it needed. After notifyObjectLoaded I can request the shared memory
>> and do the mapping. But this only covers one module. If I have two modules
>> for example, then I will end up having two shared memories, because the
>> second module will go through the same steps as the first one. But I want
>> to have one coherent memory.
>>
>>
>>
>> Also the applying of the mapping causes a bug with the new LLVM7 – I
>> already filled out a bug report for this. But I have no idea how things
>> will progress from that point… Still I have no idea about the system…
>>
>>
>>
>> *From:* David Blaikie <dblaikie at gmail.com>
>> *Sent:* Mittwoch, 7. November 2018 17:34
>> *To:* Gaier, Bjoern <Bjoern.Gaier at horiba.com>
>> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>
>> *Subject:* Re: [llvm-dev] JIT-Client for Shared Memory
>>
>>
>>
>> Adding Lang here in case he's got some insight.
>>
>> I take it the system you're targeting doesn't have the memory limitations
>> that some systems have, where once memory is set executable, it can never
>> be written to? & so you'd like to write some code into a page, execute it,
>> write some more code into the same page and have that execute too?
>>
>> (I don't know teh JIT architecture well enough to know if that's
>> supported, or if I'm accurately understanding your situation, etc)
>>
>> On Thu, Nov 1, 2018 at 11:49 PM Gaier, Bjoern via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>> Hello everyone,
>>
>>
>>
>> I want to use the LLVM to write a JIT client, that works with shared
>> memory. Currently I proceed as following:
>>
>>
>>
>> I wrote an own class that inherits "*RTDyldMemoryManager*". The
>> functions "*allocateCodeSection*" and "*allocateDataSection*" are
>> allocating local non-shared memory. I store there addresses in a
>> std::vector.
>>
>> When the function "*notifyObjectLoaded*" is invoked, I allocate the
>> shared memory - I'm getting the size from the local non-shared memory - and
>> apply the address mapping.
>>
>> When the function "*finalizeMemory*" is invoked I copy the code from the
>> local non-shared memory to the shared memory but only one time.
>>
>>
>>
>> So far so good, this works actually good! Yippie x3
>>
>>
>>
>> BUT... There is one problem. The shared memory can't be dynamical
>> adjusted. So if I add another module to the current module, then I would go
>> through this process again! Not the "*finalizeMemory*" process though,
>> but I would allocate another shared memory. This is not what I want!
>> Currently I use the linker first, to work around this problem, but this
>> will not help me if I add object files or libraries to the JIT process - or
>> does it?
>>
>>
>>
>> So is there any way to work around this?
>>
>>
>>
>> Kind greetings
>>
>> Björn
>>
>> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
>> USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
>> Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima.
>> Junichi Tajika
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
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>>
>> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
>> USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
>> Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima.
>> Junichi Tajika
>>
>
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