[Bug target/99488] New: dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[Bug target/99488] New: dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[doko at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

            Bug ID: 99488
           Summary: dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1:
                    Found two copies of .debug_line_str section
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: doko at debian dot org
  Target Milestone: ---

seen with trunk 20210306 on mips64el-linux-gnu, trying to run dwz on the
unstripped go1 binary.

according to
https://buildd.debian.org/status/fetch.php?pkg=gcc-11&arch=mips64el&ver=11-20210306-1&stamp=1615188915&raw=1

running dwz on the other binaries cc1, cc1plus, ... doesn't show this issue.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[doko at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

Matthias Klose <doko at debian dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |syq at debian dot org
      Known to work|                            |10.2.1
             Target|                            |mips64el-linux-gnu
      Known to fail|                            |11.0

--- Comment #1 from Matthias Klose <doko at debian dot org> ---
<mjw> doko, odd, don't know how that happens, something must have missed
merging the sections together.
<mjw> doko, Since this is mips there might be some confusion about section
types/flags. I would look to see if those sections have different types/flags
and then try to work back who created which with those. e.g. both gas and gcc
can create a .debug_line_str section.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, can you post readelf -Wa go1 output before dwz is called on it?

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[mark at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #3 from Mark Wielaard <mark at gcc dot gnu.org> ---
So gcc/dwarf2out.c creates it as:

#define DEBUG_STR_SECTION_FLAGS                                 \
  (HAVE_GAS_SHF_MERGE && flag_merge_debug_strings               \
   ? SECTION_DEBUG | SECTION_MERGE | SECTION_STRINGS | 1        \
   : SECTION_DEBUG)

        debug_line_str_section = get_section (DEBUG_LINE_STR_SECTION,
                                              DEBUG_STR_SECTION_FLAGS, NULL);

And gas/dwarf2dbg.c sets the flags as:

      bfd_set_section_flags (line_str_seg,
                             SEC_READONLY | SEC_DEBUGGING | SEC_OCTETS
                             | SEC_MERGE | SEC_STRINGS);

I hope that results in the same section type/flags set. But you should probably
check because MIPS has some special cases.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Guess we can try what happens when using -fno-merge-debug-strings with recent
binutils...

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[doko at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #5 from Matthias Klose <doko at debian dot org> ---
Created attachment 50387
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50387&action=edit
readelf -Wa output

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[doko at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #6 from Matthias Klose <doko at debian dot org> ---
https://people.debian.org/~doko/tmp/go1-mips64el.xz

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
  [43] .debug_line_str   MIPS_DWARF      0000000000000000 ecf07bf 0066e6 01  MS
 0   0  1
  [44] .debug_line_str   MIPS_DWARF      0000000000000000 ecf6ea5 0005d1 01  MS
 0   0  1
Thus, doesn't seem to be dwz fault, the two .debug_line_str sections is
something unexpected.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[mark at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #8 from Mark Wielaard <mark at gcc dot gnu.org> ---
On Mon, 2021-03-15 at 12:21 +0000, jakub at gcc dot gnu.org wrote:
> --- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
>   [43] .debug_line_str   MIPS_DWARF      0000000000000000 ecf07bf 0066e6 01  MS
>  0   0  1
>   [44] .debug_line_str   MIPS_DWARF      0000000000000000 ecf6ea5 0005d1 01  MS
>  0   0  1
> Thus, doesn't seem to be dwz fault, the two .debug_line_str sections is
> something unexpected.

But that is odd. It has the same name, section type, flags (merge
strings) and alignment. Why didn't the linker merge these?

The only difference with other arches would be the MIPS_DWARF instead
of PROGBITS type. But that shouldn't really matter to the linker.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Sure.
One interesting question is whether there are *.o objects with multiple
.debug_line_str sections (but even if there are, shouldn't the linker merge
them?).
So primary suspect here is the linker.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #10 from YunQiang Su <syq at debian dot org> ---
I noticed that there are two go1 file: the first one has no this problem, and
the second one has this problem:

The difference of them the the option to generate them:

    -fno-checking
vs
    -fchecking=1 -flto=jobserver

I will continue to dig it.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #11 from YunQiang Su <syq at debian dot org> ---
This problem will happen when gcc is configured with
    --with-build-config=bootstrap-lto-lean
Option.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #12 from YunQiang Su <syq at debian dot org> ---
This problem disappears if we build gcc 11 with binutils 2.36.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #13 from YunQiang Su <syq at debian dot org> ---
(In reply to Jakub Jelinek from comment #9)
> Sure.
> One interesting question is whether there are *.o objects with multiple
> .debug_line_str sections (but even if there are, shouldn't the linker merge
> them?).
> So primary suspect here is the linker.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=956954
another example, while it seem has some different:

root@mipsel:/build/innoextract/innoextract-1.8# readelf -Wa
debian/innoextract/usr/bin/innoextract | grep debug_info
  [32] .debug_info       MIPS_DWARF      00000000 09a8c0 1b77ef 00      0   0 
1
  [40] .debug_info       PROGBITS        00000000 4ff4b4 50302b 00      0   0 
1

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #14 from YunQiang Su <syq at debian dot org> ---
The problem sees due to some problem of LTO.

Index: binutils-2.36.50.20210618/bfd/elfxx-mips.c
===================================================================
--- binutils-2.36.50.20210618.orig/bfd/elfxx-mips.c
+++ binutils-2.36.50.20210618/bfd/elfxx-mips.c
@@ -7448,7 +7448,9 @@ _bfd_mips_elf_section_from_shdr (bfd *ab
       break;
     case SHT_MIPS_DWARF:
       if (! startswith (name, ".debug_")
-         && ! startswith (name, ".zdebug_"))
+         && ! startswith (name, ".gnu.debuglto_.debug_")
+         && ! startswith (name, ".zdebug_")
+         && ! startswith (name, ".gnu.debuglto_..zdebug_"))
        return false;
       break;
     case SHT_MIPS_SYMBOL_LIB:
@@ -7669,7 +7671,9 @@ _bfd_mips_elf_fake_sections (bfd *abfd,
       hdr->sh_entsize = sizeof (Elf_External_ABIFlags_v0);
     }
   else if (startswith (name, ".debug_")
-          || startswith (name, ".zdebug_"))
+          || startswith (name, ".gnu.debuglto_.debug_")
+          || startswith (name, ".zdebug_")
+          || startswith (name, ".gnu.debuglto_.zdebug_"))
     {
       hdr->sh_type = SHT_MIPS_DWARF;

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #15 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to YunQiang Su from comment #14)
> The problem sees due to some problem of LTO.

So I if understand correctly this binutils patch is fixes the issue?  If so
please close this bug as moved and open up a binutils bug and submit the patch
there.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Are you sure about the .. in one of the zdebug section names?

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #17 from YunQiang Su <syq at debian dot org> ---
(In reply to Jakub Jelinek from comment #16)
> Are you sure about the .. in one of the zdebug section names?

It is a typo.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #18 from YunQiang Su <syq at debian dot org> ---
(In reply to Andrew Pinski from comment #15)
> (In reply to YunQiang Su from comment #14)
> > The problem sees due to some problem of LTO.
> 
> So I if understand correctly this binutils patch is fixes the issue?  If so
> please close this bug as moved and open up a binutils bug and submit the
> patch there.

Yes. It should be the fix.
While it is about the MIPS psABI and dwarf spec.
so we still need to some comment about this solution.

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #19 from YunQiang Su <syq at debian dot org> ---
It is a bug of binutils:

https://sourceware.org/bugzilla/show_bug.cgi?id=28009

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[syq at debian dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

--- Comment #20 from YunQiang Su <syq at debian dot org> ---
(In reply to Andrew Pinski from comment #15)
> (In reply to YunQiang Su from comment #14)
> > The problem sees due to some problem of LTO.
> 
> So I if understand correctly this binutils patch is fixes the issue?  If so
> please close this bug as moved and open up a binutils bug and submit the
> patch there.

I have no permission to close this bug report.
Can you help me to do so?

[Bug target/99488] dwz: /usr/lib/gcc/mips64el-linux-gnuabi64/11/go1: Found two copies of .debug_line_str section

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99488

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |MOVED

--- Comment #21 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Marking as moved as requested.