This patch is the first in a series of patches that will eventually add support
for IEEE 128-bit floating point support to the PowerPC GCC compiler.  At the
current time, we do not plan to change the default for long double.  I added a
new type keyword (__float128) to get access to IEEE 128-bit floating point, and
another (__ibm128) to get access to IBM extended double type.

Until all of the GCC and LIBGCC patches have been committed, you will not be
able to use IEEE 128-bit floating point, and -mfloat128-software will not be
turned on by default.

This patch adds the new modes (KFmode and IFmode) and the switches
(-mfloat128-{none,software}).

Due to the fact that TFmode in the PowerPC compiler either represents IEEE
128-bit floating point or the IBM extended double (double-double) format.  For
most PowerPC users, the default is to use IBM extended double for long double.
Because TFmode can be either floating point format, I added new new modes:

	KFmode	-- IEEE 128-bit floating point
	IFmode	-- IBM extended double floating point

If the default for TFmode is ibm extended double, the port will eventually use
KFmode for IEEE 128-bit floating point.  Likewise if the default for TFmode is
IEEE 128-bit floating point, the port will use TFmode for IEEE 128-bit floating
point, and IFmode for IBM extended double.

I have bootstraped these patches on a power7 and compared them to the unpatched
compiler.  There were no changes when running make check.  Are these patches ok
to install in the trunk?

2015-05-22  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/rs6000-modes.def (IFmode): Define IFmode to
	provide access to the IBM extended double floating point mode if
	long double is IEEE 128-bit floating point.
	(KFmode): Define KFmode to provide access to IEEE 128-bit floating
	point if long double is the IBM extended double type.

	* config/rs6000/rs6000.opt (-mfloat128-none): New switches to
	enable adding IEEE 128-bit floating point support.
	(-mfloat128-software): Likewise.
	(-mfloat128-sw): Likewise.

	* config/rs6000/rs6000.c (rs6000_hard_regno_mode_ok): Do not allow
	128-bit floating point types to occupy any register if
	-mlong-double-64.  Do not allow use of IFmode/KFmode unless
	-mfloat128-software is enabled.
	(rs6000_debug_reg_global): Add IEEE 128-bit floating point debug
	support.
	(rs6000_option_override_internal): Add -mfloat128-* support.
	(rs6000_init_builtins): Setup __ibm128 and __float128 type modes.

	* config/rs6000/rs6000.h (rs6000_builtin_type_index): Add ibm128
	and float128 type nodes.
	(ieee128_float_type_node): Likewise.
	(ibm128_float_type_node): Likewise.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797