powerpc: Fix the compiler type used with C++ when -mabi=ieeelongdouble

When compiling C++ code with -mabi=ieeelongdouble, KCtype is
unavailable and the long double type should be used instead.

This is also providing macro __HAVE_FLOAT128_UNLIKE_LDBL in order to
identify the kind of long double type is being used in the current
compilation unit.
Notice that bits/floatn.h cannot benefit from the new macro due to order
of header inclusion.

	* bits/floatn-common.h: Define __HAVE_FLOAT128_UNLIKE_LDBL.
	* math/math.h: Restrict the prototype definition for the functions
	issignaling(_Float128) and iszero(_Float128); and template
	__iseqsig_type<_Float128>, from __HAVE_DISTINCT_FLOAT128 to
	__HAVE_FLOAT128_UNLIKE_LDBL.
	* sysdeps/powerpc/bits/floatn.h [__HAVE_FLOAT128
	&& (!__GNUC_PREREQ (7, 0) || defined __cplusplus)
	&& __LDBL_MANT_DIG__ == 113]: Use long double suffix for
	__f128() constants; define the type _Float128 as long double;
	and reuse long double in __CFLOAT128.

Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/bits/floatn-common.h b/bits/floatn-common.h
index 070cdd0247..1d8958a193 100644
--- a/bits/floatn-common.h
+++ b/bits/floatn-common.h
@@ -56,6 +56,13 @@
 #define __HAVE_DISTINCT_FLOAT64X 0
 #define __HAVE_DISTINCT_FLOAT128X __HAVE_FLOAT128X
 
+/* Defined to 1 if the corresponding _FloatN type is not binary compatible
+   with the corresponding ISO C type in the current compilation unit as
+   opposed to __HAVE_DISTINCT_FLOATN, which indicates the default types built
+   in glibc.  */
+#define __HAVE_FLOAT128_UNLIKE_LDBL (__HAVE_DISTINCT_FLOAT128	\
+				     && __LDBL_MANT_DIG__ != 113)
+
 /* Defined to 1 if any _FloatN or _FloatNx types that are not
    ABI-distinct are however distinct types at the C language level (so
    for the purposes of __builtin_types_compatible_p and _Generic).  */