How to track down a bad llvm optimization pass

[Joakim via digitalmars-d-ldc]

On Monday, 20 June 2016 at 20:15:52 UTC, Rainer Schuetze wrote:
>
>
> On 19.06.2016 08:58, Joakim wrote:
>> On Sunday, 19 June 2016 at 06:45:42 UTC, Dan Olson wrote:
>>> Dan Olson <gorox at comcast.net> writes:
>>>
>>>> Joakim <dlang at joakim.fea.st> writes:
>>>>
>>>>> [...]
>>>>
>>>> And I am trying opposite: builting ldc master against llvm 
>>>> 3.8.0.
>>>> See if I can duplicate the problem.
>>>
>>> Yup, fails same way on a Raspberry Pi with 3.8.0.
>>
>> And it's still hitting on llvm 3.9 master svn-271934 from a 
>> couple weeks
>> ago, looks like we'll have to submit a bug report.  Anyone 
>> know if we're
>> breaking some llvm assumptions here?
>
> If it fails in a specific optimization pass, it has already 
> passed a number of verification passes. When I posted some bug 
> reports, the LLVM people (who have been very helpful) 
> considered it an LLVM bug if an invalid IR passes the verifier. 
> So even if some assumptions are broken, I would suggest to 
> report to the LLVM bug tracker.

OK, will do.  I think the fact that the exact same ldc frontend 
linked with llvm 3.7.1 doesn't have this problem, only when 
linked against llvm 3.8.0, indicates this most likely isn't a 
problem on our end.