Re: Patch, Split powerpc -mfloat128 into 2 parts

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

On Tue, Oct 04, 2016 at 09:42:21PM +0000, Joseph Myers wrote:
> On Tue, 4 Oct 2016, Michael Meissner wrote:
> 
> > It also changes __ibm128/__float128, and only registers the keywords if the
> > long double type is not IBM extended double or IEEE 128-bit floating point
> > respectively.  If the long double type matches one of those types, instead it
> > will issue a #define {__ibm128,__float128} long double, and the user will
> > always pick up the long double type.
> 
> _Float128, when it exists, is always a distinct type from long double even 
> if they are ABI-compatible.  So if they are ABI-compatible, you would have 
> __float128 the same as long double but different from _Float128, which 
> seems confusing - are you doing it that way because of the lack of 
> _Float128 in C++ means a simple define to _Float128 could only be used for 
> C?

I have removed the #define of __float128, and instead created a keyword that
points to the _Float128 type.  I added a little commentary on the use of
__ieee128 (which is needed to create the type when we aren't using __float128).

I did a bootstrap and test on a little endian power8 system with no
regressions.  Can I install the patch on the trunk?

[gcc]
2016-10-05  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/rs6000-c.c (rs6000_cpu_cpp_builtins): Split
	-mfloat128 into -mfloat128-type that enables the IEEE 128-bit
	floating point type infrastructre, and -mfloat128 that enables the
	keyword.  Define __FLOAT128__ if -mfloat128, and __FLOAT128_TYPE__
	if -mfloat128-type.  Define __ibm128 to be long double by default.
	* config/rs6000/rs6000.c (rs6000_debug_reg_global): Print whether
	the IEEE 128-bit floating point type infrastructure should
	automatically be enabled.
	(rs6000_init_hard_regno_mode_ok): Switch to use -mfloat128-type
	instead of -mfloat128 to enable KFmode.
	(rs6000_option_override_internal): Split the option -mfloat128
	into -mfloat128-type and -mfloat128.  On Linux PowerPC 64-bit
	systems, automatically set -mfloat128-type, but don't enable it on
	other operating systems.  Move setting the long double size and
	IEEE quad support before the IEEE 128-bit floating point changes.
	(rs6000_init_builtins): Do not create a unique type for __ibm128
	if long double is IBM extended double, instead rely on __ibm128
	being defined as 'long double'.  If -mfloat128-type and not
	-mfloat128, create the KFmode type with an undocumented __ieee128
	keyword.
	(rs6000_init_libfuncs): Use -mfloat128-type instead of
	-mfloat128 for tests about the types, but keep tests for
	-mfloat128 to enable the keyword support.
	(rs6000_complex_function_value): Likewise.
	(rs6000_scalar_mode_supported_p): Likewise.
	(rs6000_floatn_mode): Likewise.
	(rs6000_c_mode_for_suffix): Likewise.
	(rs6000_opt_masks): Add -mfloat128-type.
	* config/rs6000/rs6000-cpus.def (POWERPC_MASKS): Add support for
	-mfloat128-type being split from -mfloat128.  Add
	-mfloat128-hardware, which was missing.
	* config/rs6000/rs6000.opt (-mfloat128): Split -mfloat128 into
	-mfloat128 and -mfloat128-type:
	(-mfloat128-type): Likewise.
	* config/rs6000/linux64.h (TARGET_FLOAT128_ENABLE_TYPE): Define so
	that 64-bit Linux systems with enable -mfloat128-type by default
	on VSX systems.
	* config/rs6000/rs6000.h (TARGET_FLOAT128_ENABLE_TYPE): Likewise.
	(FLOAT128_VECTOR_P): Switch IEEE 128-bit floating points to use
	-mfloat128-type instead of -mfloat128.
	(FLOAT128_2REG_P): Likewise.
	(MASK_FLOAT128_TYPE): Likewise.
	(ALTIVEC_ARG_MAX_RETURN): Likewise.
	(RS6000_BTM_FLOAT128): Likewise.
	(TARGET_FLOAT128): Poison old identifiers.
	(OPTION_MASK_FLOAT128): Likewise.
	(MASK_FLOAT128): Likewise.
	* config/rs6000/rs6000.md (FP): Likewise.
	(FLOAT128): Likewise.
	(fix_trunc<mode>di2): Likewise.
	(fixuns_trunc<IEEE128:mode><SDI:mode>2): Likewise.
	(floatdi<mode>2): Likewise.
	(floatuns<SDI:mode><IEEE128:mode>2): Likewise.
	(neg<mode>2, FLOAT128 iterator): Likewise.
	(abs<mode>2, FLOAT128 iterator): Likewise.
	(ieee_128bit_negative_zero): Likewise.
	(ieee_128bit_vsx_neg<mode>2): Likewise.
	(ieee_128bit_vsx_neg<mode>2_internal): Likewise.
	(ieee_128bit_vsx_abs<mode>2): Likewise.
	(ieee_128bit_vsx_abs<mode>2_internal): Likewise.
	(ieee_128bit_vsx_nabs<mode>2): Likewise.
	(ieee_128bit_vsx_nabs<mode>2_internal): Likewise.
	(extendiftf2): Likewise.
	(extendifkf2): Likewise.
	(extendtfkf2): Likewise.
	(trunciftf2): Likewise.
	(truncifkf2): Likewise.
	(trunckftf2): Likewise.
	(trunctfif2): Likewise.
	(extendkftf2): Likewise.
	(trunctfkf2): Likewise.

[gcc/testsuite]
2016-10-05  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* gcc.target/powerpc/float128-type-1.c: New test to check that
	PowerPC 64-bit Linux enables -mfloat128-type by default.
	* gcc.target/powerpc/float128-type-2.c: Likewise.
	* gcc.target/powerpc/float128-mix.c: Change error message to
	reflect that __ibm128 is now #define'ed to be long double.

-- 
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

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