[Bug debug/88878] .debug_pubnames/types empty with -flto

[Bug debug/88878] .debug_pubnames/types empty with -flto

[jan.kratochvil at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88878

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan.kratochvil at redhat dot com

--- Comment #7 from Jan Kratochvil <jan.kratochvil at redhat dot com> ---
Hello, @rguenth could you suggest what problem does -fdebug-types-section -flto
still have?
When I remove the use_debug_types's "&& !in_lto_p" part it looks to me as
working fine. (I haven't done any non-trivial debuginfo testing.)

Contents of the .debug_info section:
  Compilation Unit @ offset 0x0:
   Version:       4
 <0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <c>   DW_AT_producer    : (indirect string, offset: 0x0): GNU GIMPLE 10.2.1
20200723 (Red Hat 10.2.1-1) -mtune=generic -march=x86-64 -g -g -fno-openmp
-fno-openacc -fno-pie -fdebug-types-section -fltrans
    <11>   DW_AT_name        : (indirect string, offset: 0xa8): <artificial>
  Compilation Unit @ offset 0xc9:
   Version:       4
 <0><d4>: Abbrev Number: 11 (DW_TAG_compile_unit)
    <d5>   DW_AT_producer    : (indirect string, offset: 0x35a): GNU C++14
10.2.1 20200723 (Red Hat 10.2.1-1) -mtune=generic -march=x86-64 -g
-fdebug-types-section -flto
    <da>   DW_AT_name        : (indirect string, offset: 0x20e): main.C
 <1><e6>: Abbrev Number: 12 (DW_TAG_class_type)
    <e9>   DW_AT_signature   : signature: 0xf1df7e53d0fa1d2e
  Compilation Unit @ offset 0x15a:
   Version:       4
 <0><165>: Abbrev Number: 11 (DW_TAG_compile_unit)
    <166>   DW_AT_producer    : (indirect string, offset: 0x35a): GNU C++14
10.2.1 20200723 (Red Hat 10.2.1-1) -mtune=generic -march=x86-64 -g
-fdebug-types-section -flto
    <16b>   DW_AT_name        : (indirect string, offset: 0x479): lib.C
Contents of the .debug_types section:
  Compilation Unit @ offset 0x0:
   Version:       4
   Signature:     0xf1df7e53d0fa1d2e
   Type Offset:   0x25
 <0><17>: Abbrev Number: 1 (DW_TAG_type_unit)
    <19>   DW_AT_GNU_odr_signature: 0xddd94cb16fdd687a
 <1><25>: Abbrev Number: 2 (DW_TAG_class_type)

[Bug debug/88878] .debug_pubnames/types empty with -flto

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88878

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jan Kratochvil from comment #7)
> Hello, @rguenth could you suggest what problem does -fdebug-types-section
> -flto still have?
> When I remove the use_debug_types's "&& !in_lto_p" part it looks to me as
> working fine. (I haven't done any non-trivial debuginfo testing.)

The .debug_types section isn't supposed to be output when in_lto_p
(that's for the LTRANS units where we generally do not output any
types into DWARF).  Instead .debug_types has to be output during
dwarf2out_early_finish when we write the declaration dwarf units,
the "early" debug info.  That should now be done.  What's still missing
is pubnames/pubtypes I think, -fdebug-types-section works fine now.
But -gpubnames is not.

You can verify with a small testcase and -gpubnames [-flto] where
with -flto both .debug_pubtype and .debug_pubnames are missing.

But nobody complained in years so I gues -gpubnames is unused.

[Bug debug/88878] .debug_pubnames/types empty with -flto

[jan.kratochvil at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88878

--- Comment #9 from Jan Kratochvil <jan.kratochvil at redhat dot com> ---
(In reply to Richard Biener from comment #8)
> The .debug_types section isn't supposed to be output when in_lto_p
> (that's for the LTRANS units where we generally do not output any
> types into DWARF).  Instead .debug_types has to be output during
> dwarf2out_early_finish when we write the declaration dwarf units,
> the "early" debug info.  That should now be done.

Thanks for the explanation, I see -fdebug-types-section -flto does work with
trunk without any patch, great!


> You can verify with a small testcase and -gpubnames [-flto] where
> with -flto both .debug_pubtype and .debug_pubnames are missing.

I do not think anyone is interested in those, for DWARF-5 they are officially
removed:
http://www.dwarfstd.org/doc/DWARF5.pdf
 * Replace the .debug_pubnames and .debug_pubtypes sections with a single and
   more functional name index section, .debug_names .

And for DWARF-4 those were replaced by GNU .gdb_index .