[NEW BUG]: Configure broken on MIPS

[David Holmes]

On 24/03/2018 1:58 AM, Magnus Ihse Bursie wrote:
> 
> On 2018-03-23 11:05, David Holmes wrote:
>> On 23/03/2018 7:54 PM, Magnus Ihse Bursie wrote:
>>>
>>> On 2018-03-23 09:55, David Holmes wrote:
>>>> On 23/03/2018 6:46 PM, Magnus Ihse Bursie wrote:
>>>>>
>>>>> On 2018-03-23 06:22, David Holmes wrote:
>>>>>> Hi Thomas,
>>>>>>
>>>>>> On 23/03/2018 2:55 PM, Thomas Stüfe wrote:
>>>>>>> Hi David,
>>>>>>>
>>>>>>> would it not be pragmatic to accept Ao's patch - it looks fine to 
>>>>>>> me - since it certainly would not make matters worse. And let 
>>>>>>> Magnus follow up with a cleanup change later?
>>>>>>
>>>>>> Well I hope Magnus's change is forthcoming. 
>>>>> It might be some time still. I'm working on a complete overhaul of 
>>>>> all CFLAGS and LDFLAGS, where this is a part of that picture, but I 
>>>>> was not planning on addressing just this thing urgently.
>>>>>
>>>>> So, I think this patch will do for now. It solves the immediate 
>>>>> problem for MIPS, and I can come back and make a cleaner solution 
>>>>> later on.
>>>>
>>>> Isn't the best quick fix one that only adds -m64 for x86? I recall a 
>>>> report that arm32 is similarly broken.
>>> Not really, because this is also needed on some other platforms, at 
>>> least s390x, as I recall. (This was the reason it was originally added.)
>>
>> According to gcc docs there are 4 archs that use m64 and we only care 
>> about 2 of them:
>>
>> m64: SPARC Options
>> m64: S/390 and zSeries Options
>> m64: RS/6000 and PowerPC Options
>> m64: i386 and x86-64 Options
>>
> Note that this logic also applies to the xlc compiler, not only gcc. I 
> also believe that solstudio requires it on sparcv9, but I'm not 100% sure.
> 
>> But you need to know whether you are dealing with S390 or S390x as m64 
>> implies zSeries.
> We only support s390x (64-bit), not s390.
> 
> And OpenJDK still support ppc64, even if Oracle does not test it. So I'd 
> say that we need -m64 on all those platforms listed. So then the 
> question is, is it easier to check if it's one of four, or not one of 
> tree known CPU architectures. (For mips, we shouldn't test 
> OPENJDK_TARGET_CPU for a lot of mips*, but OPENJDK_TARGET_CPU_ARCH for 
> mips). For me, it's like, whatever. I'll probably rewrite this from the 
> ground up anywhat. What we're trying to express here is that some flags 
> are needed as CFLAGS always, even when running configure checks. It has 
> really nothing to do with the number of CPU bits.

My recollection for x86 was we only needed to specify -m64 to ensure a 
64-bit build if the compiler was not configured to do that by default. 
Very much tied to the number of CPU bits we wanted to build for.

In any case isn't the whole point of configure that you can check if a 
compiler has a flag before you use it ??

David

> /Magnus
> 
>>
>> Ao will need a sponsor to create a bug etc regardless of which way 
>> this goes.
>>
>> My week is over. :)
>>
>> Cheers,
>> David
>>
>>> /Magnus
>>>
>>>>
>>>> David
>>>> -----
>>>>
>>>>>> AFAICS it's as easy to write this only for x86 as it is to exclude 
>>>>>> it for non x86. Honestly I don't know why the Aarch64 patch was 
>>>>>> done the way it was - there must be some subtlety here that I'm 
>>>>>> not aware of.
>>>>> I think it was just the smallest patch that worked for the aarch64 
>>>>> platform. I didn't spend time arguing about the fix, since it is 
>>>>> supposed to be short-lived anyway.
>>>>>
>>>>> /Magnus
>>>
>