On 1/15/19 5:58 AM, Alex Bennée wrote: > > Thomas Huth <th...@redhat.com> writes: > >> On 2019-01-14 17:37, Alex Bennée wrote: >>> >>> Philippe Mathieu-Daudé <phi...@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 <th...@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... > > What about something like this: > > modified include/fpu/softfloat-macros.h > @@ -641,12 +641,6 @@ 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__) > - /* Need to use a TImode type to get an even register pair for DLGR. */ > - unsigned __int128 n = (unsigned __int128)n1 << 64 | n0; > - asm("dlgr %0, %1" : "+r"(n) : "r"(d)); > - *r = n >> 64; > - return n; > #elif defined(_ARCH_PPC64) && defined(_ARCH_PWR7) > /* From Power ISA 2.06, programming note for divdeu. */ > uint64_t q1, q2, Q, r1, r2, R; > @@ -663,6 +657,11 @@ static inline uint64_t udiv_qrnnd(uint64_t *r, uint64_t > n1, > } > *r = R; > return Q; > +#elif defined(CONFIG_INT128) > + unsigned __int128 n = (unsigned __int128)n1 << 64 | n0; > + unsigned __int128 q = n / d; > + *r = q >> 64; > + return q;
Because that is not what the assembly does, for one. But perhaps unsigned __int128 n = (unsigned __int128)n1 << 64 | n0; *r = n % d; return n / d; will allow the compiler to do what the assembly does for some 64-bit hosts. r~