[v3] Prepare vfprintf to use __printf_fp/__printf_fphex with float128 arg

Message ID 20181221190456.13436-1-gabriel@inconstante.eti.br
State New
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Series
  • [v3] Prepare vfprintf to use __printf_fp/__printf_fphex with float128 arg
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Commit Message

Gabriel F. T. Gomes Dec. 21, 2018, 7:04 p.m.
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_EXTENDED): New macro.
	(PARSE_FLOAT_VA_ARG): Likewise.
	(SETUP_FLOAT128_INFO): Likewise.
	(process_arg): Use PARSE_FLOAT_VA_ARG_EXTENDED 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                   | 18 ++++++++--
 stdio-common/printf-parse.h      |  3 ++
 stdio-common/vfprintf-internal.c | 73 +++++++++++++++++++++++++++++++++-------
 3 files changed, 78 insertions(+), 16 deletions(-)

Patch

diff --git a/libio/libioP.h b/libio/libioP.h
index 958ef9bffe..f3c1d886c0 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -705,9 +705,21 @@  extern int __vswprintf_internal (wchar_t *string, size_t maxlen,
    PRINTF_FORTIFY, when set to one, indicates that fortification checks
    are to be performed in input parameters.  This is used by the
    __*printf_chk functions, which are used when _FORTIFY_SOURCE is
-   defined to 1 or 2.  Otherwise, such checks are ignored.  */
-#define PRINTF_LDBL_IS_DBL 0x0001
-#define PRINTF_FORTIFY     0x0002
+   defined to 1 or 2.  Otherwise, such checks are ignored.
+
+   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 macros 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_LDBL_USES_FLOAT128	0x0004
 
 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 e07186ec83..9c79f3c862 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 61769e0ce1..414a08de0d 100644
--- a/stdio-common/vfprintf-internal.c
+++ b/stdio-common/vfprintf-internal.c
@@ -68,6 +68,57 @@ 
     } while (0)
 #define UNBUFFERED_P(S) ((S)->_flags & _IO_UNBUFFERED)
 
+#if __HAVE_FLOAT128_UNLIKE_LDBL
+# define PARSE_FLOAT_VA_ARG_EXTENDED(INFO)				      \
+  do									      \
+    {									      \
+      if (is_long_double						      \
+	  && (mode_flags & PRINTF_LDBL_USES_FLOAT128) != 0)		      \
+	{								      \
+	  INFO.is_binary128 = 1;					      \
+	  the_arg.pa_float128 = va_arg (ap, _Float128);			      \
+	}								      \
+      else								      \
+	{								      \
+	  PARSE_FLOAT_VA_ARG (INFO);					      \
+	}								      \
+    }									      \
+  while (0)
+#else
+# define PARSE_FLOAT_VA_ARG_EXTENDED(INFO)				      \
+  PARSE_FLOAT_VA_ARG (INFO);
+#endif
+
+#define PARSE_FLOAT_VA_ARG(INFO)					      \
+  do									      \
+    {									      \
+      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);			      \
+    }									      \
+  while (0)
+
+#if __HAVE_FLOAT128_UNLIKE_LDBL
+# define SETUP_FLOAT128_INFO(INFO)					      \
+  do									      \
+    {									      \
+      if ((mode_flags & PRINTF_LDBL_USES_FLOAT128) != 0)		      \
+	INFO.is_binary128 = is_long_double;				      \
+      else								      \
+	INFO.is_binary128 = 0;						      \
+    }									      \
+  while (0)
+#else
+# define SETUP_FLOAT128_INFO(INFO)					      \
+  do									      \
+    {									      \
+      INFO.is_binary128 = 0;						      \
+    }									      \
+  while (0)
+#endif
+
 #define done_add(val) \
   do {									      \
     unsigned int _val = val;						      \
@@ -771,10 +822,7 @@  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_EXTENDED (info);				      \
 	    ptr = (const void *) &the_arg;				      \
 									      \
 	    function_done = __printf_fp (s, &info, &ptr);		      \
@@ -787,8 +835,7 @@  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);				      \
 									      \
 	    function_done = __printf_fp (s, &fspec->info, &ptr);	      \
 	  }								      \
@@ -831,10 +878,7 @@  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_EXTENDED (info);				      \
 	    ptr = (const void *) &the_arg;				      \
 									      \
 	    function_done = __printf_fphex (s, &info, &ptr);		      \
@@ -844,8 +888,7 @@  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);				      \
 									      \
 	    function_done = __printf_fphex (s, &fspec->info, &ptr);	      \
 	  }								      \
@@ -1869,6 +1912,10 @@  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 +1934,7 @@  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