[cfe-dev] Fwd: Optimization flags causing segfault on clang

[ROHIT KUMAR via cfe-dev]

This is weird, I ran the build again and this time it showed error at a
different location.
`[image: Inline image 1]

On Fri, Jul 7, 2017 at 1:49 PM, ROHIT KUMAR <rohitpoddar92 at gmail.com> wrote:

> This is weird, I ran the build again and this time it showed error at a
> different location.
>
> [image: Inline image 1]
>
> On Fri, Jul 7, 2017 at 1:35 PM, Craig Topper <craig.topper at gmail.com>
> wrote:
>
>> That's not supposed to happen. What was the failure?
>>
>> On Fri, Jul 7, 2017 at 1:01 AM ROHIT KUMAR <rohitpoddar92 at gmail.com>
>> wrote:
>>
>>> Yes. With this flag, I got compilation failure.
>>>
>>> On Jul 7, 2017 1:28 PM, "Craig Topper" <craig.topper at gmail.com> wrote:
>>>
>>>> You got a compilation failure not a runtime failure?
>>>>
>>>> On Fri, Jul 7, 2017 at 12:19 AM ROHIT KUMAR <rohitpoddar92 at gmail.com>
>>>> wrote:
>>>>
>>>>> Thanks, Craig.
>>>>>
>>>>> So with this argument, the build failed on compilation with the last
>>>>> log as
>>>>>
>>>>> *"BISECT: NOT running pass (60626) optimize barriers pass on function
>>>>> ... "*
>>>>>
>>>>> It points to a function in a class where we also had a high suspicion
>>>>> for. So it makes sense.
>>>>>
>>>>> So it is very likely that the way our code is written is not meeting
>>>>> the standards used by clang and one or other optimization is breaking it.
>>>>>
>>>>> Do you have any idea which flag is doing this "optimize barriers pass
>>>>> on function" which we can ignore?
>>>>>
>>>>>
>>>>> On Fri, Jul 7, 2017 at 11:55 AM, Craig Topper <craig.topper at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> You can use -mllvm -opt-bisect-limit=<limit> to bisect where the
>>>>>> error occurs. More documentation here http://llvm.org/docs/OptB
>>>>>> isect.html
>>>>>>
>>>>>> ~Craig
>>>>>>
>>>>>> On Thu, Jul 6, 2017 at 11:18 PM, ROHIT KUMAR via cfe-dev <
>>>>>> cfe-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>>> Hey,
>>>>>>>
>>>>>>> Context: Android native code built with clang using Android Studio.
>>>>>>>
>>>>>>> We have been using GCC(Eclipse) for quite a while, now we are trying
>>>>>>> to move our huge code base to clang (to AndroidStudio).
>>>>>>>
>>>>>>> With GCC we were using -O3 optimization and everything was working
>>>>>>> fine, but with clang, even -O1 is causing Android apps to crash on runtime
>>>>>>> with the seg fault.
>>>>>>>
>>>>>>> Since apps are working fine when compiled with -O0, so my guess is
>>>>>>> some kind of optimization is not supported for our code base which is/are
>>>>>>> introduced by O1/2/3 flags.
>>>>>>>
>>>>>>> Is there a way I can disable the flags introduced by -O1 one-by-one
>>>>>>> to figure out the culprit flag(s)?
>>>>>>>
>>>>>>> Can anyone suggest me such flags to disable optimizations
>>>>>>> one-by-one? I tried googling but could not find much help.
>>>>>>>
>>>>>>> I am stuck on this issue for quite a while now. I would really
>>>>>>> appreciate the help. I am looking for a more general advice on flags to
>>>>>>> disable optimizations one-by-one with -O1, because making changes in the
>>>>>>> code base would not be possible.
>>>>>>>
>>>>>>> Thanks.
>>>>>>> Rohit Kumar
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> cfe-dev mailing list
>>>>>>> cfe-dev at lists.llvm.org
>>>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>>>>
>>>>>>>
>>>>>>
>>>>> --
>>>> ~Craig
>>>>
>>> --
>> ~Craig
>>
>
>
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