Re: [Qemu-devel] [PATCH] include/fpu/softfloat: Fix compilation with Clang on s390x

[Thomas Huth <thuth@redhat.com>]

On 2019-01-14 17:37, Alex Bennée wrote:
> 
> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> 
>> On 1/14/19 1:12 PM, Thomas Huth wrote:
>>> Clang v7.0.1 does not like the __int128 variable type for inline
>>> assembly on s390x:
>>>
>>> In file included from fpu/softfloat.c:97:
>>> include/fpu/softfloat-macros.h:647:9: error: inline asm error:
>>>  This value type register class is not natively supported!
>>>     asm("dlgr %0, %1" : "+r"(n) : "r"(d));
>>>         ^
>>>
>>> Disable this code part there now when compiling with Clang, so that
>>> the generic code gets used instead.
>>>
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>> ---
>>>  include/fpu/softfloat-macros.h | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
>>> index b1d772e..bd5b641 100644
>>> --- a/include/fpu/softfloat-macros.h
>>> +++ b/include/fpu/softfloat-macros.h
>>> @@ -641,7 +641,7 @@ static inline uint64_t udiv_qrnnd(uint64_t *r, uint64_t n1,
>>>      uint64_t q;
>>>      asm("divq %4" : "=a"(q), "=d"(*r) : "0"(n0), "1"(n1), "rm"(d));
>>>      return q;
>>> -#elif defined(__s390x__)
>>> +#elif defined(__s390x__) && !defined(__clang__)
>>
>> Can we rather check if __int128 is natively supported? So this part get
>> compiled once Clang do support it, else we'll never use it...
> 
> We already define CONFIG_INT128 so you could just use that.
> 
> Thomas does the s390 clang leave CONFIG_INT128=y in config-host.mak?

Yes, CONFIG_INT128=y is also set with Clang on s390x. It's really just
that it does not like __int128  to be passed as parameters for inline
assembly...

 Thomas