Re: [PATCH v3] Enable inlining issignalingf within glibc (was "v2")

[Paul Clarke <pc at us dot ibm dot com>]

Sorry, this should've been noted as "v3".  ugh

On 9/30/19 8:51 AM, Paul A. Clarke wrote:
> From: "Paul A. Clarke" <pc@us.ibm.com>
> 
> issignalingf is a very small function used in some areas where
> better performance (and smaller code) might be helpful.
> 
> Create inline implementation for issignalingf.
> 
> 2019-09-30  Paul A. Clarke  <pc@us.ibm.com>
> 
> 	* sysdeps/generic/math_private.h (GET_FLOAT_WORD, SET_FLOAT_WORD):
> 	Moved...
> 	* include/math.h (GET_FLOAT_WORD, SET_FLOAT_WORD): to here.
> 	(__issignalingf): New, copied from
> 	sysdeps/iee754/flt-32/s_issignalingf.c.
> ---
> v2:
> - New approach as suggested by Joseph Myers: no implementations in
>   math_private.h, instead in include/math.h.
> - Moved GET_FLOAT_WORD from math_private.h to include/math.h in support.
> - Brought along matching SET_FLOAT_WORD for consistency.
> 
>  include/math.h                 | 53 ++++++++++++++++++++++++++++++++++++++++++
>  sysdeps/generic/math_private.h | 29 -----------------------
>  2 files changed, 53 insertions(+), 29 deletions(-)
> 
> diff --git a/include/math.h b/include/math.h
> index 79ebbae..a274f2b 100644
> --- a/include/math.h
> +++ b/include/math.h
> @@ -54,6 +54,59 @@ libm_hidden_proto (__expf128)
>  libm_hidden_proto (__expm1f128)
>  # endif
> 
> +#include <stdint.h>
> +#include <nan-high-order-bit.h>
> +
> +/* A union which permits us to convert between a float and a 32 bit
> +   int.  */
> +
> +typedef union
> +{
> +  float value;
> +  uint32_t word;
> +} ieee_float_shape_type;
> +
> +/* Get a 32 bit int from a float.  */
> +#ifndef GET_FLOAT_WORD
> +# define GET_FLOAT_WORD(i,d)					\
> +do {								\
> +  ieee_float_shape_type gf_u;					\
> +  gf_u.value = (d);						\
> +  (i) = gf_u.word;						\
> +} while (0)
> +#endif
> +
> +/* Set a float from a 32 bit int.  */
> +#ifndef SET_FLOAT_WORD
> +# define SET_FLOAT_WORD(d,i)					\
> +do {								\
> +  ieee_float_shape_type sf_u;					\
> +  sf_u.word = (i);						\
> +  (d) = sf_u.value;						\
> +} while (0)
> +#endif
> +
> +extern inline int
> +__issignalingf (float x)
> +{
> +  uint32_t xi;
> +  GET_FLOAT_WORD (xi, x);
> +#if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
> +  /* We only have to care about the high-order bit of x's significand, because
> +     having it set (sNaN) already makes the significand different from that
> +     used to designate infinity.  */
> +  return (xi & 0x7fc00000) == 0x7fc00000;
> +#else
> +  /* To keep the following comparison simple, toggle the quiet/signaling bit,
> +     so that it is set for sNaNs.  This is inverse to IEEE 754-2008 (as well as
> +     common practice for IEEE 754-1985).  */
> +  xi ^= 0x00400000;
> +  /* We have to compare for greater (instead of greater or equal), because x's
> +     significand being all-zero designates infinity not NaN.  */
> +  return (xi & 0x7fffffff) > 0x7fc00000;
> +#endif
> +}
> +
>  # if __HAVE_DISTINCT_FLOAT128
> 
>  /* __builtin_isinf_sign is broken in GCC < 7 for float128.  */
> diff --git a/sysdeps/generic/math_private.h b/sysdeps/generic/math_private.h
> index d91b929..9296324 100644
> --- a/sysdeps/generic/math_private.h
> +++ b/sysdeps/generic/math_private.h
> @@ -153,35 +153,6 @@ do {								\
>  } while (0)
>  #endif
> 
> -/* A union which permits us to convert between a float and a 32 bit
> -   int.  */
> -
> -typedef union
> -{
> -  float value;
> -  uint32_t word;
> -} ieee_float_shape_type;
> -
> -/* Get a 32 bit int from a float.  */
> -#ifndef GET_FLOAT_WORD
> -# define GET_FLOAT_WORD(i,d)					\
> -do {								\
> -  ieee_float_shape_type gf_u;					\
> -  gf_u.value = (d);						\
> -  (i) = gf_u.word;						\
> -} while (0)
> -#endif
> -
> -/* Set a float from a 32 bit int.  */
> -#ifndef SET_FLOAT_WORD
> -# define SET_FLOAT_WORD(d,i)					\
> -do {								\
> -  ieee_float_shape_type sf_u;					\
> -  sf_u.word = (i);						\
> -  (d) = sf_u.value;						\
> -} while (0)
> -#endif
> -
>  /* We need to guarantee an expansion of name when building
>     ldbl-128 files as another type (e.g _Float128).  */
>  #define mathx_hidden_def(name) hidden_def(name)
> 
PC