[debug] Add debug and earlydebug dumps

[debug] Add debug and earlydebug dumps

With the introduction of early debug, we've added a phase in the compiler which
produces information which is not visible, unless we run the compiler in the
debugger and call debug_dwarf from dwarf2out_early_finish or some such.

This patch adds dumping of "early" and "final" debug info, into .earlydebug
and .debug dump files, enabled by -fdump-earlydebug and -fdumpdebug, such that
we can follow f.i. the upper bound of a vla type from early debug:
...
          DW_AT_upper_bound: location descriptor:
            (0x7f0d645b7550) DW_OP_GNU_variable_value , 0
...
to final debug:
...
          DW_AT_upper_bound: location descriptor:
            (0x7f0d645b7550) DW_OP_fbreg 18446744073709551592, 0
            (0x7f0d645b7a00) DW_OP_deref 8, 0
...
to -dA annotated assembly file:
...
        .uleb128 0x3    # DW_AT_upper_bound
        .byte   0x91    # DW_OP_fbreg
        .sleb128 -24
        .byte   0x6     # DW_OP_deref
...

The .debug file shows the same information as the annotated assembly, but in
the same format as the "early" debug info.

Bootstrapped and reg-tested on x86_64.

2018-08-21  Tom de Vries  <tdevries@suse.de>

	* cgraph.h (debuginfo_early_init, debuginfo_init, debuginfo_fini)
	(debuginfo_start, debuginfo_stop, debuginfo_early_start)
	(debuginfo_early_stop): Declare.
	* cgraphunit.c (debuginfo_early_init, debuginfo_init, debuginfo_fini)
	(debuginfo_start, debuginfo_stop, debuginfo_early_start)
	(debuginfo_early_stop): New function.
	(symbol_table::finalize_compilation_unit): Call debuginfo_early_start
	and debuginfo_early_stop.
	* dwarf2out.c (dwarf2out_finish, dwarf2out_early_finish): Dump dwarf.
	* toplev.c (compile_file): Call debuginfo_start and debuginfo_stop.
	(general_init): Call debuginfo_early_init.
	(finalize): Call debuginfo_fini.
	(do_compile): Call debuginfo_init.
	* doc/invoke.texi (@gccoptlist): Add -fdump-debug and
	-fdump-early-debug.
	(@item -fdump-debug, @item -fdump-earlydebug): Add.

	* lto.c (lto_main):  Call debuginfo_early_start and
	debuginfo_early_stop.

	* gcc.c-torture/unsorted/dump-noaddr.x: Use -gno-record-gcc-switches
	to avoid mismatch in .debug and .earlydebug dump files.

From-SVN: r263687