[llvm-dev] [ThinLTO] Using two different IRMovers for the same composite module? (related to PR28180)

[Taewook Oh via llvm-dev]

Makes sense. I’ll try to get the code as well. 

Thanks,
Taewook

On 7/22/16, 6:13 PM, "mehdi.amini at apple.com on behalf of Mehdi Amini" <mehdi.amini at apple.com> wrote:


> On Jul 22, 2016, at 4:42 PM, Taewook Oh <twoh at fb.com> wrote:
> 
> It seems that the patch works for me as well, though the linker crashes with another error after that. Thanks!
> 
> Mehdi, I couldn’t quite understand what do you mean by you don’t have a repro so you couldn’t upstream the patch. Aren’t .ll files you attached sufficient to submit along with the patch? If there is anything I can help you to upstream it, please let me know. 

I could submit the patch as-is but it is not in my habit to do that without a total understanding of the situation, i.e. I’m not convinced the test case is totally reduced and I need to “reverse engineer” the debug metadata to get a source-code construct that would trigger this bug.

— 
Mehdi





> 
> -- Taewook
> 
> On 7/22/16, 2:52 PM, "mehdi.amini at apple.com on behalf of Mehdi Amini" <mehdi.amini at apple.com> wrote:
> 
> 
>> On Jul 22, 2016, at 2:47 PM, Davide Italiano <davide at freebsd.org> wrote:
>> 
>> On Fri, Jul 22, 2016 at 2:44 PM, Davide Italiano <davide at freebsd.org> wrote:
>>> On Fri, Jul 22, 2016 at 2:34 PM, Taewook Oh via llvm-dev
>>> <llvm-dev at lists.llvm.org> wrote:
>>>> Yes, I have the repro, though I can’t publish it externally. It would be
>>>> great if you can upstream the patch so I can try it. Thank you for your
>>>> explanation as well!
>>> 
>>> There's a reproducer attached (obtained via lld --reproduce option).
>>> If that doesn't work, you can checkout mozjs and try to reduce from
>>> there.
>>> It happens while doing an LTO build with lld.
>>> I have a fix for that (Mehdi has one as well, apparently) in my local
>>> tree, but I don't have time to reduce. If you can take care of that,
>>> chances are that an upstream fix will be committed shortly after.
>>> 
>> 
>> Just to clarify, I'm talking about the issue in PR28180. I can't
>> comment about the ThinLTO one, sorry.
> 
> If lld is setting enableDebugTypeODRUniquing(); on the context and isn’t using the IRMover to target an empty module, it can be the same bug.
> I mentioned that it should touch only ThinLTO but I had ld64 in mind.
> 
> — 
> Mehdi
> 
>