Duplicate .debug_lines (Was: [PATCH 5/5] Add --gdwarf-5 to ASM_SPEC)

[Mark Wielaard]

H.J. Lu wrote:
> On Sat, Aug 29, 2020 at 9:33 AM Mark Wielaard <mark@klomp.org> wrote:
>> Hi,
>>
>> On Sat, Aug 29, 2020 at 08:43:30AM -0700, H.J. Lu wrote:
>>> On Sat, Aug 29, 2020 at 8:23 AM Mark Wielaard <mark@klomp.org> wrote:
>>>> My proposal, and what my strawman patch implements, is that gas will
>>>> generate a .debug_line section when -g is given and the debug types is
>>>> DWARF (just as it does now). Unless there is a non-empty .debug_line
>>>> section already created by the input assembly and the input assembly
>>>> does not contain any .loc directive then gas will not try to generate
>>>> a .debug_line section itself but leaves the non-empty .debug_line as
>>>> is (currently gas will generate an error in this case). But if the
>>>> input assembly does contain both .loc directives and creates a
>>>> non-empty .debug line section gas will still generate an error (as it
>>>> does now, whether or not the input assembly contains any .loc
>>>> directives).
>>>>
>>>> Does this sound sane?
>>>
>>> What if there is a .file directive,  but without .loc directive, like
>>>
>>> $ gcc -c x.c -Wa,-g
>>
>> That situation does not change, since in that case no .debug_*
>> sections are generated in the assembly file, so gas will generate
>> everything it currently generates.
>
> Will line info be correct in this case?

Nothing about how gas generates the line table will change with the above proposal. It only changes the behaviour when the assembly already contains a line table.