re PR target/85657 (Make __ibm128 a separate type, even if long double uses the IBM double-double format)

[gcc]
2018-06-06  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_passes_ieee128): New boolean to
	track if we pass or return IEEE 128-bit floating point.
	(ieee128_mangling_gcc_8_1): New boolean to say whether to generate
	C++ mangling that is compatible with GCC 8.1.
	(TARGET_ASM_GLOBALIZE_DECL_NAME): Override target hook.
	(init_cumulative_args): Note if we pass or return IEEE 128-bit
	floating point types.
	(rs6000_function_arg_advance_1): Likewise.
	(rs6000_mangle_type): Optionally generate mangled names that match
	what GCC 8.1 generated for IEEE 128-bit floating point types.
	(rs6000_globalize_decl_name): If we have an external function that
	passes or returns IEEE 128-bit types, generate a weak reference
	from the mangled name used in GCC 8.1 to the current mangled
	name.

[gcc]
2018-06-05  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_init_builtins): Make __ibm128 use
	the long double type if long double is IBM extended double.  Make
	__float128 use the long double type if long double is IEEE 128-bit.

[gcc/testsuite]
2018-06-05  Michael Meissner  <meissner@linux.ibm.com>

	PR target/85657
	* g++.dg/pr85657.C: Only test whether __ibm128 and long double can
	be used in templates.  Don't check for them in overloaded functions.

From-SVN: r261246