Windows breakage -- again

[Johan Tibell]

Can someone see if adding

  Cc-options: -march=i686

To ghc-prim.cabal resolves the issue?
On Jul 17, 2014 9:06 PM, "Simon Marlow" <marlowsd at gmail.com> wrote:

> gcc has -march=native which uses the current CPU's architecture, but I
> think it would be a really bad idea to turn that on by default, because it
> would mean that we have to be really careful which machine we build the
> distributions on.
>
> On my Linux box, gcc -v says it was configured with --with-arch-32=i686,
> which means that -march=i686 is the default for 32-bit code.  We shouldn't
> go any later than that IMO.
>
> Anyway, this is all beside the point, if we aren't able to run the code
> generated by gcc (in whatever mode) then there's a bug somewhere.
>
> Cheers,
> Simon
>
> On 17/07/2014 07:39, Johan Tibell wrote:
>
>> Alright, then which Make file do we need to fix to make sure GCC is
>> called correctly? Also, I remember reading that some time during the
>> 4.x GCC series GCC switched to auto-detecting the arch to be that of
>> the machine being used. Could someone try to just switch GCC to a
>> newer version and see if it automatically stops trying to use i386,
>> leading to Simon's problem?
>>
>> On Thu, Jul 17, 2014 at 8:37 AM, Niklas Larsson <metaniklas at gmail.com>
>> wrote:
>>
>>> It certainly shouldn't be built with i386, because that is generating
>>> code
>>> for a processor that lacks all these fancy atomic instructions. The
>>> first of
>>> them appears on the 486.
>>>
>>> i686 should be safe, it goes all the way back to Pentium Pro.
>>>
>>>
>>> 2014-07-17 8:33 GMT+02:00 Johan Tibell <johan.tibell at gmail.com>:
>>>
>>>  A perhaps silly question, *should* ghc-prim be built with i386 or i686?
>>>>
>>>> On Thu, Jul 17, 2014 at 8:33 AM, Niklas Larsson <metaniklas at gmail.com>
>>>> wrote:
>>>>
>>>>> I just found exactly the same thing! Well, I used i686 instead.
>>>>>
>>>>> Sounds like it's worthwhile to see if this is limited to ghc-prim or if
>>>>> there's more stuff that's built with i386.
>>>>>
>>>>>
>>>>> 2014-07-17 8:21 GMT+02:00 Páli Gábor János <pali.gabor at gmail.com>:
>>>>>
>>>>>  2014-07-17 0:51 GMT+02:00 Páli Gábor János <pali.gabor at gmail.com>:
>>>>>>
>>>>>>> 2014-07-17 0:47 GMT+02:00 Niklas Larsson <metaniklas at gmail.com>:
>>>>>>>
>>>>>>>> I hope they can just be done away with at the source, that is to
>>>>>>>> make
>>>>>>>> gcc
>>>>>>>> generate the assembly primitives. GHC should already be built with
>>>>>>>> i686, but
>>>>>>>> does that reach ghc-prim?
>>>>>>>>
>>>>>>>
>>>>>>> This depends on GCC -- if no -march=XXX is explicitly set, I guess it
>>>>>>> will take its default, which may vary platform by platform.
>>>>>>>
>>>>>>
>>>>>> All right, I have finally got a Windows (x64) machine and installed
>>>>>> the msys2 environment by the GHC wiki [1].  This has GCC 4.5.2 (as
>>>>>> Niklas wrote earlier), where the default -march is i386.  You should
>>>>>> see this line when trying to compile Johan's test program with the -v
>>>>>> flag set:
>>>>>>
>>>>>> COLLECT_GCC_OPTIONS= ... '-v' '-mtune=i386' '-march=i386'
>>>>>>
>>>>>> With the -march=i586 flag explicitly set in the command line, no
>>>>>> __sync_fetch_and_add_n() calls are generated.
>>>>>>
>>>>>> [1]
>>>>>>
>>>>>> https://ghc.haskell.org/trac/ghc/wiki/Building/Preparation/
>>>>>> Windows/MSYS2
>>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
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