[LLVMdev] Sporadic "RealOffset <= INT32_MAX && RealOffset >= INT32_MIN" failures with MCJIT on Windows

Sat May 23 14:25:28 PDT 2015

The commits in question are r234839 and you'll probably also want r236341.
I don't think these are the kinds of commits that should generally be back
ported. It's not really a small self-contained commit. If you're willing
you can probably carry these patches yourself (we will be doing so on top
of 3.6 until 3.7 is released), but do note that in my experience using
MCJIT with the large code model does not quite work yet (it's on my todo
list to work out exactly why and fit). Also, I believe the memory
allocation scheme for MCJIT was rewritten slightly between 3.5 and trunk,
so there may be additional problems I don't know about.

On Sat, May 23, 2015 at 5:12 PM, Eric Christopher <echristo at gmail.com>
wrote:

> Hi Dale,
>
> I don't think that Keno's rewrite is applicable for a bug fix release. We
> have, in the last year, moved to having some dot releases for our older
> releases, but these are definitely bug fix only and low risk as we don't
> want to break anything new.
>
> The release documentation is located here:
>
> http://llvm.org/docs/HowToReleaseLLVM.html
>
> for future reference. There's no official long term support strategy past
> the information on that page, previously we released every 6 mos without
> dot releases at all so this is a fairly new trial for us. Backporting of
> patches is at the discretion of the author, the code owner, and the release
> manager.
>
> Keno: perfectly happy to entertain a backport of your patch if you want to
> do such a thing, but IIRC it was a bit more than a simple bug fix.
>
> -eric
>
> On Sat, May 23, 2015 at 7:28 AM Dale Martin <Dale.Martin at mathworks.com>
> wrote:
>
>>  This sounds pretty serious and it won't be easy for us to upgrade -
>> particularly not to trunk.  Are there plans to take bug fixes like this
>> into llvm 3.5.x point releases?  (Do I remember right that 3.5.x is
>> supposed to have some kind of long term support?  Where is that process
>> documented?)
>>
>>
>>  Thanks,
>>
>>   Dale
>>
>>
>>  ------------------------------
>> *From:* Lang Hames <lhames at gmail.com>
>> *Sent:* Friday, May 22, 2015 7:55 PM
>> *To:* Keno Fischer
>> *Cc:* Ramkumar Ramachandra; Peng Cheng; LLVMdev; Dale Martin
>> *Subject:* Re: [LLVMdev] Sporadic "RealOffset <= INT32_MAX && RealOffset
>> >= INT32_MIN" failures with MCJIT on Windows
>>
>>
>>  On Fri, May 22, 2015 at 4:14 PM, Keno Fischer <
>> kfischer at college.harvard.edu> wrote:
>>
>>> This might be related to GOT relocations. I rewrote that part of
>>> RuntimeDyldELFbecause I was seeing this issue. Have you tried trunk?
>>>
>>
>>  I didn't notice that you were running 3.5 the first time I read this.
>> Keno's diagnosis is very likely to be correct. You should try trunk if
>> you're able to.
>>
>>  - Lang.
>>
>> On Fri, May 22, 2015 at 4:14 PM, Keno Fischer <
>> kfischer at college.harvard.edu> wrote:
>>
>>> This might be related to GOT relocations. I rewrote that part of
>>> RuntimeDyldELFbecause I was seeing this issue. Have you tried trunk?
>>>
>>> On Fri, May 22, 2015 at 5:10 PM, Ramkumar Ramachandra <
>>> artagnon at gmail.com> wrote:
>>>
>>>> So it appears that we get about half the crashes with the large code
>>>> model. The rest are crashing in the same way. It could either mean that
>>>> large code model still takes that crashing codepath and that the number of
>>>> crashes only went down by chance, or that in one place in the flow, large
>>>> code model is not matched to mean ELF::R_X86_64_PC64. I'm digging into this
>>>> issue further, but any hints along the way would be appreciated.
>>>>
>>>>  Thanks.
>>>>
>>>>  Ram
>>>>
>>>> On Tue, May 19, 2015 at 12:06 PM, Reid Kleckner <rnk at google.com> wrote:
>>>>
>>>>> That sounds like a PC-relative relocation failure. Usually this
>>>>> happens when the relocation target is more than 2 GB away from the source.
>>>>> Try using the large code model or tweaking the memory manager.
>>>>>
>>>>>  It turns out it's surprisingly hard to portably allocate some memory
>>>>> and then allocate some more within a 2 GB offset of the first allocation in
>>>>> a 64-bit process. For various reasons that I don't understand, reserving 2
>>>>> GB of address space upfront and allocating from that is not workable for
>>>>> some MCJIT clients.
>>>>>
>>>>>  On Tue, May 19, 2015 at 7:19 AM, Ramkumar Ramachandra <
>>>>> artagnon at gmail.com> wrote:
>>>>>
>>>>>>  Hi,
>>>>>>
>>>>>>  We are seeing sporadic crashes since we migrated to MCJIT on Win64.
>>>>>> The same tests pass without issues on Mac64 and Linux64. The issue is this
>>>>>> assertion failure in RuntimeDyldELF.c:
>>>>>>
>>>>>>    RealOffset <= INT32_MAX && RealOffset >= INT32_MIN
>>>>>>
>>>>>>  I haven't managed to successfully catch the failure in Visual to
>>>>>> try and debug it. Any tips on how to make progress?
>>>>>>
>>>>>>  Oh, and we're on LLVM 3.5.
>>>>>>
>>>>>>  Thanks.
>>>>>>
>>>>>>  Ram
>>>>>>
>>>>>>  _______________________________________________
>>>>>> LLVM Developers mailing list
>>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>>>
>>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>>
>>   _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150523/bb17f6e3/attachment.html>