[llvm-dev] [ThinLTO] static library failure with object files with the same name

[Mehdi AMINI via llvm-dev]

It is expected and not unusual to need to update the lit test in such case.
I'd need to see exactly which test breaks and how to know though.

Best,

-- 
Mehdi

2017-09-18 13:17 GMT-07:00 Johan Engelen <jbc.engelen at gmail.com>:

> The fix (https://reviews.llvm.org/D37961) does not work.  From what I
> have learned thusfar, the module identifier is used as filename sometimes
> (I think when writing an intermediate module index summary), and so a bunch
> of lit tests fail with the "fix".
>
> I'll look further into fixing this, any help is appreciated.
>
> ( One thing that may be important is to have a deterministic suffix. The
> counter solution of https://reviews.llvm.org/D37961 would name the same
> module differently depending on order, which may happen when doing thinlto
> in several different steps. Adding the size of the module (or its offset)
> would be the same in each invocation. Regardless, changing the suffix to a
> size suffix does not fix the lit test problems. )
>
> regards,
>   Johan
>
>
>
> On Sun, Sep 17, 2017 at 6:32 PM, Johan Engelen <jbc.engelen at gmail.com>
> wrote:
>
>> I've created a review for your patch Mehdi: https://reviews.llvm.or
>> g/D37961
>>
>> First time using `arc`, so hope things went well.
>>
>> - Johan
>>
>>
>> On Tue, Sep 12, 2017 at 5:25 AM, Mehdi AMINI <joker.eph at gmail.com> wrote:
>>
>>> Hi Johan,
>>>
>>> 2017-09-11 14:21 GMT-07:00 Johan Engelen <jbc.engelen at gmail.com>:
>>>
>>>> On Fri, Sep 8, 2017 at 9:04 PM, Johan Engelen <jbc.engelen at gmail.com>
>>>> wrote:
>>>>
>>>>>
>>>>> On Thu, Sep 7, 2017 at 5:44 PM, Mehdi AMINI <joker.eph at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Hi Johan,
>>>>>>
>>>>>> ld64 only calls functions from llvm/include/llvm-c/lto.h  (defined
>>>>>> in llvm/tools/lto/lto.cpp)
>>>>>>
>>>>>> For instance ThinLTOCodeGenerator::addModule is called
>>>>>> through thinlto_codegen_add_module().
>>>>>>
>>>>>> Apple hasn't released the code for ld64 in Xcode 9 yet, did you check
>>>>>> if it is fixed in Xcode 9?
>>>>>> (I think I remember fixing it in ld64 but I'm not totally sure...).
>>>>>>
>>>>>
>>>>> I haven't tried with Xcode 9.
>>>>>
>>>>>
>>>>>>
>>>>>> From what I can see with Xcode 8.2, the linker just passes the file
>>>>>> name (prefixed with the archive name): https://github.com/michaelweis
>>>>>> er/ld64/blob/master/src/ld/parsers/lto_file.cpp#L546
>>>>>> (original here: https://opensource.apple
>>>>>> .com/source/ld64/ld64-274.2/src/ld/parsers/lto_file.cpp.auto.html )
>>>>>>
>>>>>> We could workaround this in ThinLTOCodeGenerator by adding a
>>>>>> incremental suffix to every new buffer. Something like this diff:
>>>>>>
>>>>>
>>>>> I was assuming that we do want to assert/error on calling addModule
>>>>> with the exact same module twice? Otherwise your diff is nice, thanks.
>>>>>
>>>>>
>>>>
>>>> Hi Mehdi,
>>>>   Can you advise me?
>>>> Is it OK to not error upon the exact same module being added twice?
>>>> (and thus your patch would be good)
>>>>
>>>>
>>> It is a matter of API contract, so I'm not sure I perceive a clear
>>> right/wrong here. If we want to enforce an API contract on the caller's
>>> responsibility to provide a unique ID, then the assert may be OK (however
>>> we disable assertions in production and it means random crashes which isn't
>>> super user-friendly).
>>> On the other hand my patch here was trying to be resilient to API misuse
>>> for "little cost".
>>>
>>> Note that the plan was that this API (and the ThinLTOCodegenerator.cpp)
>>> should just die, but unfortunately I haven't had time to work on the
>>> replacement (a C binding for the new LTO API).
>>>
>>> --
>>> Mehdi
>>>
>>
>>
>
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