* optabs.c (init_floating_libfuncs): Handle decimal float modes.
	(init_optabs): Handle libfuncs for decimal float.
	* genopinit.c (gen_insn): Handle MODE_DECIMAL_FLOAT.
	* stor-layout.c (int_mode_for_mode): Likewise.
	* simplify-rtx.c (simplify_immed_subreg): Likewise.
	(simplify_unary_operation_1): Skip optimisations for decimal float
	modes.
	* varasm.c (output_constant_pool_2): Handle MODE_DECIMAL_FLOAT.
	* emit-rtl.c (gen_const_vector): Add assertion check.
	(init_emit_once): Populate const_tiny_rtx with constants in each
	decimal float mode.
	* expmed.c (extract_high_half, expand_mult_highpart_optab,
	expand_mult_highpart): Assert that mode is not a scalar float
	mode.
	* expr.c (convert_move): Handle conversion between decimal and
	binary floats of the same size.
	* convert.c (convert_to_real): Consider decimal float types when
	folding.
	* dwarf2out.c (base_type_die): Use DW_ATE_decimal_float to
	describe decimal floating point types.

Co-Authored-By: Ben Elliston <bje@au.ibm.com>
Co-Authored-By: Janis Johnson <janis187@us.ibm.com>

From-SVN: r108762