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

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

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))
>