DWARF add DW_AT_noreturn on noreturn function subprogram.

This implements the DWARFv5 noreturn proposal:
http://dwarfstd.org/ShowIssue.php?issue=140331.1

TREE_THIS_VOLATILE on a FUNCTION_DECL node means the function does not
return normally. This catches the traditional noreturn GNU attribute,
the C11 _Noreturn keyword and the C++11 [[noreturn]] attribute.

This relies on the DW_AT_noreturn constant defined in the DWARFv5 DRAFT:
http://www.dwarfstd.org/doc/dwarf5.20141029.pdf

gcc/ChangeLog

	* dwarf2out.c (gen_subprogram_die): Add DW_AT_noreturn when the
	function decl has TREE_THIS_VOLATILE.

gcc/testsuite/ChangeLog

	* g++.dg/debug/dwarf2/noreturn-function.C: New test.
	* gcc.dg/debug/dwarf2/noreturn-function-attribute.c: Likewise.
	* gcc.dg/debug/dwarf2/noreturn-function-keyword.c: Likewise.

include/ChangeLog

	* dwarf2.def (DW_AT_noreturn): New DWARF5 attribute.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@218075 138bc75d-0d04-0410-961f-82ee72b054a4
2014-11-26  Richard Biener  <rguenther@suse.de>

	* gimple-fold.c (get_symbol_constant_value): Allow all
	GIMPLE register type zero-constants.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@218076 138bc75d-0d04-0410-961f-82ee72b054a4
PR debug/38757 continued. Handle C11, C++11 and C++14.

Add experimental (minimal) DWARFv5 support.

This change depends on the new DWARFv5 constants mentioned in the
following draft: http://dwarfstd.org/doc/dwarf5.20141029.pdf

gcc/ChangeLog

	* doc/invoke.texi (-gdwarf-@{version}): Mention experimental DWARFv5.
	* opts.c (common_handle_option): Accept -gdwarf-5.
	* dwarf2out.c (is_cxx): Add DW_LANG_C_plus_plus_11 and
	DW_LANG_C_plus_plus_14.
	(lower_bound_default): Likewise. Plus DW_LANG_C11.
	(gen_compile_unit_die): Output DW_LANG_C_plus_plus_11,
	DW_LANG_C_plus_plus_14 or DW_LANG_C11.
	(output_compilation_unit_header): Output at most a DWARFv4 header.
	(output_skeleton_debug_sections): Likewise.
	(output_line_info): Likewise.
	(output_aranges): Document header version number.

gcc/testsuite/ChangeLog

	* gcc.dg/debug/dwarf2/lang-c11.c: New test.
	* gcc.dg/debug/dwarf2/lang-c11-d4-strict.c: Likewise.
	* g++.dg/debug/dwarf2/lang-cpp11.C: Likewise.
	* g++.dg/debug/dwarf2/lang-cpp14.C: Likewise.
	* g++.dg/debug/dwarf2/lang-cpp98.C: Likewise.

include/ChangeLog

	* dwarf2.h: Add DW_LANG_C_plus_plus_11, DW_LANG_C11 and
	DW_LANG_C_plus_plus_14.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@218077 138bc75d-0d04-0410-961f-82ee72b054a4