Re: [PATCH] math: Enable some math builtins for clang

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

If there is no objection, I will commit this shortly.

On 08/02/2019 16:56, Adhemerval Zanella wrote:
> Ping.
> 
> On 01/02/2019 10:48, Adhemerval Zanella wrote:
>> This patch enable the builtin usage for clang for the C99 functions
>> fpclassify, isfinite, isnormal, isnan, isinf, and sigbit.  This allows
>> clang optimize the calls on frontend instead of call the appropriate
>> glibc symbols.
>>
>> Checked on aarch64-linux-gnu and x86_64-linux-gnu. I checked the supported
>> version for each builtin based on released version from clang/llvm.
>>
>> 	* math/math.h (fpclassify, isfinite, isnormal, isnan): Use builtin for
>> 	clang 2.8.
>> 	(signbit): Use builtin for clang 3.3.
>> 	(isinf): Use builtin for clang 3.7.
>> ---
>>  ChangeLog   |  7 +++++++
>>  math/math.h | 17 +++++++++++------
>>  2 files changed, 18 insertions(+), 6 deletions(-)
>>
>> diff --git a/math/math.h b/math/math.h
>> index ffbc24af09..d70ec3877c 100644
>> --- a/math/math.h
>> +++ b/math/math.h
>> @@ -874,7 +874,8 @@ enum
>>     the __SUPPORT_SNAN__ check may be skipped for those versions.  */
>>  
>>  /* Return number of classification appropriate for X.  */
>> -# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__			      \
>> +# if ((__GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__)		      \
>> +      || __glibc_clang_prereq (2,8))					      \
>>       && (!defined __OPTIMIZE_SIZE__ || defined __cplusplus)
>>       /* The check for __cplusplus allows the use of the builtin, even
>>  	when optimization for size is on.  This is provided for
>> @@ -889,7 +890,7 @@ enum
>>  # endif
>>  
>>  /* Return nonzero value if sign of X is negative.  */
>> -# if __GNUC_PREREQ (6,0)
>> +# if __GNUC_PREREQ (6,0) || __glibc_clang_prereq (3,3)
>>  #  define signbit(x) __builtin_signbit (x)
>>  # elif defined __cplusplus
>>    /* In C++ mode, __MATH_TG cannot be used, because it relies on
>> @@ -907,14 +908,16 @@ enum
>>  # endif
>>  
>>  /* Return nonzero value if X is not +-Inf or NaN.  */
>> -# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
>> +# if (__GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__) \
>> +     || __glibc_clang_prereq (2,8)
>>  #  define isfinite(x) __builtin_isfinite (x)
>>  # else
>>  #  define isfinite(x) __MATH_TG ((x), __finite, (x))
>>  # endif
>>  
>>  /* Return nonzero value if X is neither zero, subnormal, Inf, nor NaN.  */
>> -# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
>> +# if (__GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__) \
>> +     || __glibc_clang_prereq (2,8)
>>  #  define isnormal(x) __builtin_isnormal (x)
>>  # else
>>  #  define isnormal(x) (fpclassify (x) == FP_NORMAL)
>> @@ -922,7 +925,8 @@ enum
>>  
>>  /* Return nonzero value if X is a NaN.  We could use `fpclassify' but
>>     we already have this functions `__isnan' and it is faster.  */
>> -# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
>> +# if (__GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__) \
>> +     || __glibc_clang_prereq (2,8)
>>  #  define isnan(x) __builtin_isnan (x)
>>  # else
>>  #  define isnan(x) __MATH_TG ((x), __isnan, (x))
>> @@ -939,7 +943,8 @@ enum
>>  #  define isinf(x) \
>>      (__builtin_types_compatible_p (__typeof (x), _Float128) \
>>       ? __isinff128 (x) : __builtin_isinf_sign (x))
>> -# elif __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
>> +# elif (__GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__) \
>> +       || __glibc_clang_prereq (3,7)
>>  #  define isinf(x) __builtin_isinf_sign (x)
>>  # else
>>  #  define isinf(x) __MATH_TG ((x), __isinf, (x))
>>