* tree.h (CONSTRUCTOR_BITFIELD_P): True if NODE, a FIELD_DECL, is
	to be processed as a bitfield for constructor output purposes.
	* output.h (initializer_constant_valid_for_bitfield_p): Declare
	new function.
	* varasm.c (oc_local_state): New type, output_constructor
	local state to support communication with helpers.
	(oc_outer_state): New type, output_constructor outer state of
	relevance in recursive calls.
	(output_constructor_array_range): New output_constructor helper,
	extracted code for an array range element.
	(output_constructor_regular_field): New output_constructor helper,
	extracted code for an element that is not a bitfield.
	(output_constructor_bitfield): New output_constructor helper,
	extracted code for a bitfield element.  Accept an OUTER state
	argument for recursive processing.  Recurse on record or array
	CONSTRUCTOR values, possibly past noop conversions.
	(initializer_constant_valid_for_bitfield_p): New predicate. Whether
	VALUE is a valid constant-valued expression for use in a static
	bit-field initializer.
	(output_constructor): Rework to use helpers. Accept and honor an
	OUTER state argument for recursive calls. Return total size. Be
	prepared for nested constructors initializing bitfields.
	(output_constant): Feed OUTER in calls to output_constructor.

	ada/
	* gcc-interface/utils2.c (gnat_build_constructor): Factor
	out code. Use initializer_constant_valid_for_bitfield_p and
	CONSTRUCTOR_BITFIELD_P for bit-fields.

	testsuite/
	* gnat.dg/oconst[1-6].ad[bs]: New tests. Also support for ...
	* gnat.dg/test_oconst.adb: New test.


Co-Authored-By: Eric Botcazou <ebotcazou@adacore.com>

From-SVN: r148045