Wrong file name entry in .debug_info section

[kamlesh kumar]

Thanks for reply Nick.

But, when we do not pass -P option to gcc it is gives correct file name why?
Like:
gcc -g -c -xassembler-with-cpp hello.s
readelf --debug-dump hello.o | grep DW_AT_name

DW_AT_name    : hello.s

~Kamlesh

On Fri, Aug 3, 2018 at 4:10 PM Nick Clifton <nickc@redhat.com> wrote:

> Hi Kamlesh,
>
> > gcc -g -c -xassembler-with-cpp -P hello.s
> > readelf --debug-dump hello.o | grep DW_AT_name
> >
> > I get following:
> >
> > DW_AT_name       :/tmp/cc8P6Tw2.s
> >
> > which is a temporary file generated by compiler now no more exist.>
> > Why gas is putting wrong file name there.
>
> Because that is the name of the input file that is passed to the assembler.
>
> You can work around this in a rather cumbersome fashion by saving the
> compiler's
> output into a temporary file of your own that is named after the input
> file:
>
>   gcc -g -S -xassembler-with-cpp -P hello.s > /tmp/hello.s
>   gcc -g -o hello.o /tmp/hello.s
>   readelf --debug-dump hello.o | grep DW_AT_name
>
>     <20>   DW_AT_name        : (indirect string, offset: 0x0): /tmp/hello.s
>
> And of course you can play games with temporary directories in
> order to get rid of the /tmp/ prefix to the DW_AT_name value.
>
>
> > Even if compiler put *.file="hello.s" * at top of hello.s .
> > why gas is not using that info?
>
> Because there can be multiple .file directives in a single assembler source
> file, so the assembler does not know which one to choose.  Nor does it know
> that the input file name is incorrect.  The user might very well have
> created
> a file called cc8P6Tw2.s, it is not for the assembler to decide that this
> name
> is invalid.
>
> Cheers
>   Nick
>