Ping. Re: [PATCH v5] Prepare vfprintf to use __printf_fp/__printf_fphex with float128 arg

["Gabriel F. T. Gomes" <gabriel at inconstante dot eti dot br>]

Hi,

Any more comments on this patch?  I believe I have addressed all
concerns, so I'm planning to merge it by the end of the week.

Thanks.

On Tue, May 21 2019, Gabriel F. T. Gomes wrote:
> Changes since v4:
> 
>   - Fixed typo in comment (s/macros/macro).
>   - Replaced macros with inline functions.
> 
> Changes since v3
> 
>   - Update after the commit 2d9837c1fbf4 ('Set behavior of sprintf-like
>     functions with overlapping source and destination').
> 
> Changes since v2:
> 
>   - Fixed style error in `do { ... } while (0)' blocks.
>   - Zero-initialize args_value[cnt] with memset, rather than relying on
>     the `.pa_long_double' member being the largest of the members.
> 
> Changes since v1:
> 
>   - Updated to the revised and integrated patches for __ldbl_is_dbl
>     removal, i.e.: the patches in the following thread:
>     <https://sourceware.org/ml/libc-alpha/2018-12/msg00186.html>.
>     - Added description for the PRINTF_LDBL_USES_FLOAT128 macro.
>     - Removed the LDBL_USES_FLOAT128 macro.
>   - Added `do { } while (0)' to the PARSE_FLOAT_VA_ARG_EXTENDED,
>     PARSE_FLOAT_VA_ARG, and SETUP_FLOAT128_INFO macros.  Appended
>     expansions with `;', accordingly.
> 
> -- 8< --
> On powerpc64le, long double can currently take two formats: the same as
> double (-mlong-double-64) or IBM Extended Precision (default with
> -mlong-double-128 or explicitly with -mabi=ibmlongdouble).  The internal
> implementation of printf-like functions is aware of these possibilities
> and properly parses floating-point values from the variable arguments,
> before making calls to __printf_fp and __printf_fphex.  These functions
> are also aware of the format possibilities and know how to convert both
> formats to string.
> 
> When library support for TS 18661-3 was added to glibc, __printf_fp and
> __printf_fphex were extended with support for an additional type
> (__float128/_Float128) with a different format (binary128).  Now that
> powerpc64le is getting support for its third long double format, and
> taking into account that this format is the same as the format of
> __float128/_Float128, this patch extends __vfprintf_internal to properly
> call __printf_fp and __printf_fphex with this new format.
> 
> Tested for powerpc64le (with additional patches to actually enable the
> use of these preparations) and for x86_64.
> 
> 	* libio/libioP.h (PRINTF_LDBL_USES_FLOAT128): New macro to be
> 	used as a mask for the mode argument of __vfprintf_internal.
> 	* stdio-common/printf-parse.h (printf_arg): New union member:
> 	pa_float128.
> 	* stdio-common/vfprintf-internal.c (parse_float_va_arg)
> 	(setup_float128_info): New functions.
> 	(process_arg): Use parse_float_va_arg and setup_float128_info.
> 	[__HAVE_FLOAT128_UNLIKE_LDBL] (printf_positional): Write
> 	floating-point value to the new union member, pa_float128.
> 	(printf_positional): Zero-initialize args_value[cnt] with memset.
> ---
>  libio/libioP.h                   | 20 +++++++++++---
>  stdio-common/printf-parse.h      |  3 ++
>  stdio-common/vfprintf-internal.c | 60 +++++++++++++++++++++++++++++++---------
>  3 files changed, 66 insertions(+), 17 deletions(-)
> 
> diff --git a/libio/libioP.h b/libio/libioP.h
> index 7bdec86a62..8e7e7ff9b3 100644
> --- a/libio/libioP.h
> +++ b/libio/libioP.h
> @@ -708,10 +708,22 @@ extern int __vswprintf_internal (wchar_t *string, size_t maxlen,
>     defined to 1 or 2.  Otherwise, such checks are ignored.
>  
>     PRINTF_CHK indicates, to the internal function being called, that the
> -   call is originated from one of the __*printf_chk functions.  */
> -#define PRINTF_LDBL_IS_DBL 0x0001
> -#define PRINTF_FORTIFY     0x0002
> -#define PRINTF_CHK	   0x0004
> +   call is originated from one of the __*printf_chk functions.
> +
> +   PRINTF_LDBL_USES_FLOAT128 is used on platforms where the long double
> +   format used to be different from the IEC 60559 double format *and*
> +   also different from the Quadruple 128-bits IEC 60559 format (such as
> +   the IBM Extended Precision format on powerpc or the 80-bits IEC 60559
> +   format on x86), but was later converted to the Quadruple 128-bits IEC
> +   60559 format, which is the same format that the _Float128 always has
> +   (hence the `USES_FLOAT128' suffix in the name of the flag).  When set
> +   to one, this macro indicates that long double values are to be
> +   handled as having this new format.  Otherwise, they should be handled
> +   as the previous format on that platform.  */
> +#define PRINTF_LDBL_IS_DBL		0x0001
> +#define PRINTF_FORTIFY			0x0002
> +#define PRINTF_CHK			0x0004
> +#define PRINTF_LDBL_USES_FLOAT128	0x0008
>  
>  extern size_t _IO_getline (FILE *,char *, size_t, int, int);
>  libc_hidden_proto (_IO_getline)
> diff --git a/stdio-common/printf-parse.h b/stdio-common/printf-parse.h
> index 397508638d..00f3280b8a 100644
> --- a/stdio-common/printf-parse.h
> +++ b/stdio-common/printf-parse.h
> @@ -57,6 +57,9 @@ union printf_arg
>      unsigned long long int pa_u_long_long_int;
>      double pa_double;
>      long double pa_long_double;
> +#if __HAVE_FLOAT128_UNLIKE_LDBL
> +    _Float128 pa_float128;
> +#endif
>      const char *pa_string;
>      const wchar_t *pa_wstring;
>      void *pa_pointer;
> diff --git a/stdio-common/vfprintf-internal.c b/stdio-common/vfprintf-internal.c
> index ead2b04cb9..1e98208078 100644
> --- a/stdio-common/vfprintf-internal.c
> +++ b/stdio-common/vfprintf-internal.c
> @@ -150,6 +150,42 @@ typedef wchar_t THOUSANDS_SEP_T;
>  /* Include the shared code for parsing the format string.  */
>  #include "printf-parse.h"
>  
> +static void
> +parse_float_va_arg (struct printf_info *info, union printf_arg *the_arg,
> +		    int is_long_double, unsigned int mode_flags,
> +		    va_list *ap)
> +{
> +#if __HAVE_FLOAT128_UNLIKE_LDBL
> +  if (is_long_double && (mode_flags & PRINTF_LDBL_USES_FLOAT128) != 0)
> +    {
> +      info->is_binary128 = 1;
> +      the_arg->pa_float128 = va_arg (*ap, _Float128);
> +    }
> +  else
> +#endif
> +    {
> +      info->is_binary128 = 0;
> +      if (is_long_double)
> +	the_arg->pa_long_double = va_arg (*ap, long double);
> +      else
> +	the_arg->pa_double = va_arg (*ap, double);
> +    }
> +}
> +
> +static void
> +setup_float128_info (struct printf_info *info, int is_long_double,
> +		     unsigned int mode_flags)
> +{
> +#if __HAVE_FLOAT128_UNLIKE_LDBL
> +  if ((mode_flags & PRINTF_LDBL_USES_FLOAT128) != 0)
> +    info->is_binary128 = is_long_double;
> +  else
> +    info->is_binary128 = 0;
> +#else
> +  info->is_binary128 = 0;
> +#endif
> +}
> +
>  
>  #define	outchar(Ch)							      \
>    do									      \
> @@ -771,10 +807,8 @@ static const uint8_t jump_table[] =
>  					.wide = sizeof (CHAR_T) != 1,	      \
>  					.is_binary128 = 0};		      \
>  									      \
> -	    if (is_long_double)						      \
> -	      the_arg.pa_long_double = va_arg (ap, long double);	      \
> -	    else							      \
> -	      the_arg.pa_double = va_arg (ap, double);			      \
> +	    parse_float_va_arg (&info, &the_arg, is_long_double,	      \
> +				mode_flags, &ap);			      \
>  	    ptr = (const void *) &the_arg;				      \
>  									      \
>  	    function_done = __printf_fp (s, &info, &ptr);		      \
> @@ -787,8 +821,7 @@ static const uint8_t jump_table[] =
>  		fspec->data_arg_type = PA_DOUBLE;			      \
>  		fspec->info.is_long_double = 0;				      \
>  	      }								      \
> -	    /* Not supported by *printf functions.  */			      \
> -	    fspec->info.is_binary128 = 0;				      \
> +	    setup_float128_info (&fspec->info, is_long_double, mode_flags);   \
>  									      \
>  	    function_done = __printf_fp (s, &fspec->info, &ptr);	      \
>  	  }								      \
> @@ -831,10 +864,8 @@ static const uint8_t jump_table[] =
>  					.wide = sizeof (CHAR_T) != 1,	      \
>  					.is_binary128 = 0};		      \
>  									      \
> -	    if (is_long_double)						      \
> -	      the_arg.pa_long_double = va_arg (ap, long double);	      \
> -	    else							      \
> -	      the_arg.pa_double = va_arg (ap, double);			      \
> +	    parse_float_va_arg (&info, &the_arg, is_long_double,	      \
> +				mode_flags, &ap);			      \
>  	    ptr = (const void *) &the_arg;				      \
>  									      \
>  	    function_done = __printf_fphex (s, &info, &ptr);		      \
> @@ -844,8 +875,7 @@ static const uint8_t jump_table[] =
>  	    ptr = (const void *) &args_value[fspec->data_arg];		      \
>  	    if (__glibc_unlikely ((mode_flags & PRINTF_LDBL_IS_DBL) != 0))    \
>  	      fspec->info.is_long_double = 0;				      \
> -	    /* Not supported by *printf functions.  */			      \
> -	    fspec->info.is_binary128 = 0;				      \
> +	    setup_float128_info (&fspec->info, is_long_double, mode_flags);   \
>  									      \
>  	    function_done = __printf_fphex (s, &fspec->info, &ptr);	      \
>  	  }								      \
> @@ -1869,6 +1899,10 @@ printf_positional (FILE *s, const CHAR_T *format, int readonly_format,
>  	    args_value[cnt].pa_double = va_arg (*ap_savep, double);
>  	    args_type[cnt] &= ~PA_FLAG_LONG_DOUBLE;
>  	  }
> +#if __HAVE_FLOAT128_UNLIKE_LDBL
> +	else if ((mode_flags & PRINTF_LDBL_USES_FLOAT128) != 0)
> +	  args_value[cnt].pa_float128 = va_arg (*ap_savep, _Float128);
> +#endif
>  	else
>  	  args_value[cnt].pa_long_double = va_arg (*ap_savep, long double);
>  	break;
> @@ -1887,7 +1921,7 @@ printf_positional (FILE *s, const CHAR_T *format, int readonly_format,
>  	      (args_value[cnt].pa_user, ap_savep);
>  	  }
>  	else
> -	  args_value[cnt].pa_long_double = 0.0;
> +	  memset (&args_value[cnt], 0, sizeof (args_value[cnt]));
>  	break;
>        case -1:
>  	/* Error case.  Not all parameters appear in N$ format
> -- 
> 2.14.5
>