Prepare vfscanf to use __strtof128_internal

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 scanf-like functions is aware of these possibilites
and, based on the format in use, properly calls __strtold_internal or
__strtod_internal, saving the return to a variable of type double or
long double.

When library support for TS 18661-3 was added to glibc, a new function,
__strtof128_internal, was added to enable reading of floating-point
values with IEEE binary128 format into the _Float128 type.  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, this patch extends __vfscanf_internal and __vfwscanf_internal
to call __strtof128_internal or __wcstof128_internal when appropriate.
The result gets saved into a variable of _Float128 type.

Tested for powerpc64le.

1 files changed, 15 insertions, 3 deletions

diff --git a/libio/libioP.h b/libio/libioP.h
index ce5228e382..958ef9bffe 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -759,9 +759,21 @@ extern off64_t _IO_seekpos_unlocked (FILE *, off64_t, int)
    allocation for input strings with %as, %aS and %a[, a GNU extension,
    is disabled. This is the behavior that the __isoc99_scanf family of
    functions use.  When the flag is set to zero, automatic allocation is
-   enabled.  */
-#define SCANF_LDBL_IS_DBL 0x0001
-#define SCANF_ISOC99_A    0x0002
+   enabled.
+
+   SCANF_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 SCANF_LDBL_IS_DBL		0x0001
+#define SCANF_ISOC99_A			0x0002
+#define SCANF_LDBL_USES_FLOAT128	0x0004
 
 extern int __vfscanf_internal (FILE *fp, const char *format, va_list argp,
 			       unsigned int flags)