or1k: Initial support for FPU

or1k: Initial support for FPU

This adds support for OpenRISC hardware floating point instructions.
This is enabled with the -mhard-float option.

Double-prevision floating point operations work using register pairing as
specified in: https://openrisc.io/proposals/orfpx64a32.  This has just been
added in the OpenRISC architecture specification 1.3.
This is enabled with the -mdouble-float option.

Not all architectures support unordered comparisons so an option,
-munordered-float is added.

Currently OpenRISC does not support sf/df or df/sf conversions, but this has
also just been added in architecture specification 1.3.

gcc/ChangeLog:

	* config.gcc (or1k*-*-*): Add mhard-float, mdouble-float, msoft-float
	and munordered-float validations.
	* config/or1k/constraints.md (d): New register constraint.
	* config/or1k/predicates.md (fp_comparison_operator): New.
	* config/or1k/or1k.c (or1k_print_operand): Add support for printing 'd'
	operands.
	(or1k_expand_compare): Normalize unordered comparisons.
	* config/or1k/or1k.h (reg_class): Define DOUBLE_REGS.
	(REG_CLASS_NAMES): Add "DOUBLE_REGS".
	(REG_CLASS_CONTENTS): Add contents for DOUBLE_REGS.
	* config/or1k/or1k.md (type): Add fpu.
	(fpu): New instruction reservation.
	(F, f, fr, fi, FI, FOP, fop): New.
	(<fop><F:mode>3): New ALU instruction definition.
	(float<fi><F:mode>2): New conversion instruction definition.
	(fix_trunc<F:mode><fi>2): New conversion instruction definition.
	(fpcmpcc): New code iterator.
	(*sf_fp_insn): New instruction definition.
	(cstore<F:mode>4): New expand definition.
	(cbranch<F:mode>4): New expand definition.
	* config/or1k/or1k.opt (msoft-float, mhard-float, mdouble-float,
	munordered-float): New options.
	* doc/invoke.texi: Document msoft-float, mhard-float, mdouble-float and
	munordered-float.

From-SVN: r273650