[PATCH 03/39] x86: Define __HAVE_FLOAT128 for Clang and use __builtin_*f128 code path

[Sam James]

Sam James <sam@gentoo.org> writes:

> "H.J. Lu" <hjl.tools@gmail.com> writes:
>
>> From: Fangrui Song <i@maskray.me>
>>
>> Clang supports __builtin_fabsf128 (despite not supporting _Float128) but
>> it does not support __builtin_fabsq.  Fallback to back to
>> `typedef __float128 _Float128;` it clang is used.
>>
>> Originally developed by Fangrui Song <maskray@google.com>.
>> Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
>
> I need to check previous patch revisions to see if Joseph commented on
> this one. 

I read the old comments and am happy now:

Reviewed-by: Sam James <sam@gentoo.org>

>
>> ---
>>  sysdeps/x86/bits/floatn.h | 24 ++++++++++++++++--------
>>  1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/sysdeps/x86/bits/floatn.h b/sysdeps/x86/bits/floatn.h
>> index e661abaea4..ba030d270a 100644
>> --- a/sysdeps/x86/bits/floatn.h
>> +++ b/sysdeps/x86/bits/floatn.h
>> @@ -28,7 +28,8 @@
>>     support, for x86_64 and x86.  */
>>  #if (defined __x86_64__							\
>>       ? __GNUC_PREREQ (4, 3)						\
>> -     : (defined __GNU__ ? __GNUC_PREREQ (4, 5) : __GNUC_PREREQ (4, 4)))
>> +     : (defined __GNU__ ? __GNUC_PREREQ (4, 5) : __GNUC_PREREQ (4, 4))) \
>> +    || __glibc_clang_prereq (3, 4)
>>  # define __HAVE_FLOAT128 1
>>  #else
>>  # define __HAVE_FLOAT128 0
>> @@ -58,7 +59,9 @@
>>  /* Defined to concatenate the literal suffix to be used with _Float128
>>     types, if __HAVE_FLOAT128 is 1. */
>>  # if __HAVE_FLOAT128
>> -#  if !__GNUC_PREREQ (7, 0) || (defined __cplusplus && !__GNUC_PREREQ (13, 0))
>> +#  if !__GNUC_PREREQ (7, 0) \
>> +      || (defined __cplusplus && !__GNUC_PREREQ (13, 0)) \
>> +      || defined __clang__
>>  /* The literal suffix f128 exists only since GCC 7.0.  */
>>  #   define __f128(x) x##q
>>  #  else
>> @@ -68,7 +71,9 @@
>>  
>>  /* Defined to a complex binary128 type if __HAVE_FLOAT128 is 1.  */
>>  # if __HAVE_FLOAT128
>> -#  if !__GNUC_PREREQ (7, 0) || (defined __cplusplus && !__GNUC_PREREQ (13, 0))
>> +#  if !__GNUC_PREREQ (7, 0) \
>> +      || (defined __cplusplus && !__GNUC_PREREQ (13, 0)) \
>> +      || defined __clang__
>>  /* Add a typedef for older GCC compilers which don't natively support
>>     _Complex _Float128.  */
>>  typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
>> @@ -82,12 +87,14 @@ typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__TC__)));
>>  # if __HAVE_FLOAT128
>>  
>>  /* The type _Float128 exists only since GCC 7.0.  */
>> -#  if !__GNUC_PREREQ (7, 0) || (defined __cplusplus && !__GNUC_PREREQ (13, 0))
>> +#  if !__GNUC_PREREQ (7, 0) \
>> +      || (defined __cplusplus && !__GNUC_PREREQ (13, 0)) \
>> +      || __glibc_clang_prereq (3, 4)
>>  typedef __float128 _Float128;
>>  #  endif
>>  
>> -/* __builtin_huge_valf128 doesn't exist before GCC 7.0.  */
>> -#  if !__GNUC_PREREQ (7, 0)
>> +/* __builtin_huge_valf128 doesn't exist before GCC 7.0 nor Clang 7.0.  */
>> +#  if !__GNUC_PREREQ (7, 0) && !__glibc_clang_prereq (7, 0)
>>  #   define __builtin_huge_valf128() ((_Float128) __builtin_huge_val ())
>>  #  endif
>>  
>> @@ -96,7 +103,7 @@ typedef __float128 _Float128;
>>     Converting a narrower sNaN to _Float128 produces a quiet NaN, so
>>     attempts to use _Float128 sNaNs will not work properly with older
>>     compilers.  */
>> -#  if !__GNUC_PREREQ (7, 0)
>> +#  if !__GNUC_PREREQ (7, 0) && !defined __clang__
>>  #   define __builtin_copysignf128 __builtin_copysignq
>>  #   define __builtin_fabsf128 __builtin_fabsq
>>  #   define __builtin_inff128() ((_Float128) __builtin_inf ())
>> @@ -107,7 +114,8 @@ typedef __float128 _Float128;
>>  /* In math/math.h, __MATH_TG will expand signbit to __builtin_signbit*,
>>     e.g.: __builtin_signbitf128, before GCC 6.  However, there has never
>>     been a __builtin_signbitf128 in GCC and the type-generic builtin is
>> -   only available since GCC 6.  */
>> +   only available since GCC 6.  signbit is expanded to __builtin_signbit
>> +   after Clang 3.3.  */
>>  #  if !__GNUC_PREREQ (6, 0)
>>  #   define __builtin_signbitf128 __signbitf128
>>  #  endif