https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101431
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #5)
> (In reply to Richard Biener from comment #4)
> > > cat tmp/t.c
> > void foo(int i) {}
> > > gcc-11 -g -o tmp/t.o tmp/t.c -c
> >
> > and the DWARF ends up
> >
> > <0><c>: Abbrev Number: 1 (DW_TAG_compile_unit)
> > <d> DW_AT_producer : (indirect string, offset: 0x0): GNU C17 11.1.1
> > 20210428 -mtune=generic -march=x86-64 -g
> > <11> DW_AT_language : 29 (C11)
> > <12> DW_AT_name : (indirect line string, offset: 0x0): tmp/t.c
> > <16> DW_AT_comp_dir : (indirect line string, offset: 0x8): /
> > <1a> DW_AT_low_pc : 0x0
> > <22> DW_AT_high_pc : 0xa
> > <2a> DW_AT_stmt_list : 0x0
> >
> > ...
> > The Directory Table (offset 0x22, lines 2, columns 1):
> > Entry Name
> > 0 (indirect line string, offset: 0xa): tmp
> > 1 (indirect line string, offset: 0xe): tmp
> >
> > The File Name Table (offset 0x30, lines 2, columns 2):
> > Entry Dir Name
> > 0 0 (indirect line string, offset: 0x12): tmp/t.c
> > 1 1 (indirect line string, offset: 0x1a): t.c
> >
> > I suspect this is because of how GCC and gas together end up producing
> > .debug_line - we have
> >
> > .file "t.c"
> > .text
> > ...
> > foo:
> > .LFB0:
> > .file 1 "tmp/t.c"
> > ...
> > .section .debug_line,"",@progbits
> > .Ldebug_line0:
> > .file 0 "/" "tmp/t.c"
> >
> > but this .file 0 ends up taking the place of comp-dir and it also
> > ends up duplicating the file entry for t.c unnecessarily. I'm not
> > familiar with how the DWARF5 stuff was set up so I hope somebody
> > else can have a look.
> >
> > Note the referenced testcase in github uses -gsplit-dwarf.
>
> This was with binutils 2.36.1 and GCC configured against that.
But it looks good (apart from duplicated file entry) with -gno-as-loc-support:
The Directory Table (offset 0x22, lines 2, columns 1):
Entry Name
0 (indirect line string, offset: 0x10): /
1 (indirect line string, offset: 0x0): tmp
The File Name Table (offset 0x30, lines 2, columns 2):
Entry Dir Name
0 0 (indirect line string, offset: 0x4): tmp/t.c
1 1 (indirect line string, offset: 0xc): t.c
it looks like some configury doesn't work as expected? The driver
passes --gdwarf-5 to the assembler.
