PR28149, debug info with wrong file association

PR28149, debug info with wrong file association

gcc-11 and gcc-12 pass -gdwarf-5 to gas, in order to prime gas for
DWARF 5 level debug info.  Unfortunately it seems there are cases
where the compiler does not emit a .file or .loc dwarf debug directive
before any machine instructions.  (Note that the .file directive
typically emitted as the first line of assembly output doesn't count as
a dwarf debug directive.  The dwarf .file has a file number before the
file name string.)

This patch delays allocation of file numbers for gas generated line
debug info until the end of assembly, thus avoiding any clashes with
compiler generated file numbers.  Two fixes for test case source are
necessary;  A .loc can't use a file number that hasn't already been
specified with .file.

A followup patch will remove all the gas generated line info on
seeing a .file directive.

	PR 28149
	* dwarf2dbg.c (num_of_auto_assigned): Delete.
	(current): Update initialisation.
	(set_or_check_view): Replace all accesses to view with u.view.
	(dwarf2_consume_line_info): Likewise.
	(dwarf2_directive_loc): Likewise.  Assert that we aren't generating
	line info.
	(dwarf2_gen_line_info_1): Don't call set_or_check_view on
	gas generated line entries.
	(dwarf2_gen_line_info): Set and track filenames for gas generated
	line entries.  Simplify generation of labels.
	(get_directory_table_entry): Use filename_cmp when comparing dirs.
	(do_allocate_filenum): New function.
	(dwarf2_where): Set u.filename and filenum to -1 for gas generated
	line entries.
	(dwarf2_directive_filename): Remove num_of_auto_assigned handling.
	(process_entries): Update view field access.  Call
	do_allocate_filenum.
	* dwarf2dbg.h (struct dwarf2_line_info): Add filename field in
	union aliasing view.
	* testsuite/gas/i386/dwarf2-line-3.s: Add .file directive.
	* testsuite/gas/i386/dwarf2-line-4.s: Likewise.
	* testsuite/gas/i386/dwarf2-line-4.d: Update expected output.
	* testsuite/gas/i386/dwarf4-line-1.d: Likewise.
	* testsuite/gas/i386/dwarf5-line-1.d: Likewise.
	* testsuite/gas/i386/dwarf5-line-2.d: Likewise.