On Sat, Mar 02, 2013 at 09:23:15PM +0100, Dimitry Andric wrote:
> On 2013-03-02 18:52, Andriy Gapon wrote:
> > on 02/03/2013 19:35 Andriy Gapon said the following:
> >> Now, I am not quite sure why ctfconvert skips bpobj_iterate_impl in the
> >> clang-generated code. Seems like some sort of a bug in ctfconvert.
> >
> > It seems that gcc and clang put different names for symbol of type FILE:
> > clang:
> > readelf -a -W /usr/obj/usr/src/sys/TRANT/bpobj.o| fgrep -w FILE
> > 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS
> > /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/bpobj.c
> >
> > gcc:
> > readelf -a -W /usr/obj/usr/src/sys/ODYSSEY/bpobj.o| fgrep -w FILE
> > 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS bpobj.c
> >
> > ctfconvert seems to compare this value with "bpobj.c" and so in the clang
> > case
> > it doesn't recognize the static symbols.
> >
> > Does my analysis seem reasonable?
>
> Have you verified that ctfconvert does the right thing, if you modify
> the FILE symbol to have just the filename?
>
> Indeed, clang puts the original filename from the command line in the
> .file directive, while gcc explicitly removes any directory names; see
> contrib/gcc/toplev.c, around line 680:
>
> void
> output_file_directive (FILE *asm_file, const char *input_name)
> {
> int len;
> const char *na;
>
> if (input_name == NULL)
> input_name = "<stdin>";
>
> len = strlen (input_name);
> na = input_name + len;
>
> /* NA gets INPUT_NAME sans directory names. */
> while (na > input_name)
> {
> if (IS_DIR_SEPARATOR (na[-1]))
> break;
> na--;
> }
> ...
>
> That "NA gets INPUT_NAME sans directory names" comment was inserted by
> rms in r279. :-) So I guess this is the way gcc has done it from the
> start, but there is no explanation as to why rms chose to remove those
> directory names. I do not see the problem, except maybe for having
> reproducible builds?I seems that at least gdb also depends on the stripping the path for stabs (which is not dwarf) debugging format interpretation. On the FreeBSD system, do 'info', select 'stabs' -> Stab Sections -> Elf Linker Relocation. The last paragraph documents the gdb requirements. So it seems that stripped path in the STT_FILE is the common expectation.
pgpIIMEAO2ALX.pgp
Description: PGP signature
