[Bug default/27363] New: Emit more detailed diagnostic output for "Unknown DWARF"

[Bug default/27363] New: Emit more detailed diagnostic output for "Unknown DWARF"

[d.filder at web dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=27363

            Bug ID: 27363
           Summary: Emit more detailed diagnostic output for "Unknown
                    DWARF"
           Product: dwz
           Version: unspecified
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: default
          Assignee: nobody at sourceware dot org
          Reporter: d.filder at web dot de
                CC: dwz at sourceware dot org
  Target Milestone: ---

The terseness of the current "Unknown DWARF" error messages makes it
very difficult to analyze what is going on in cases of not yet
parseable or standard-violating DWARF data.  They should give more
information, namely include:

- a hexdump of the data around the offending entity,
- whether the entity is invalid (get_DW_*_name()==NULL) or merely not
  yet handled by the code,
- current values of DW_AT_{name,producer,comp_dir,language,...},
- and instructions to include that output in the bug report and retain
  a copy of the unstripped binary for upload upon request.

From my cursory understanding the 3rd item might be easily
implementable with global variables holding copies of the most
recently seen values.

Regards,
Dennis.

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[Bug default/27363] Emit more detailed diagnostic output for "Unknown DWARF"

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27363

Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mark at klomp dot org

--- Comment #1 from Mark Wielaard <mark at klomp dot org> ---
The following commits address some of difficulty tracking down where the bad
DWARF was detected. They don't go so far as your suggestions, but I believe
they are already useful. Trying to get more information than the current (DIE)
offsets might also be tricky when we are dealing with bad DWARF.

commit 1e2beb218060515eb1e4f54a0ff6b3714b532e31 (HEAD -> master)
Author: Mark Wielaard <mark@klomp.org>
Date:   Sun Feb 21 16:55:17 2021 +0100

    Print abbrev or DIE offset for Unknown DWARF error message.

            * dwz.c (read_abbrev): Add .debug_abbrev offset to error message.
            (read_exprloc): Print DIE offset that referenced the unknown
            operand in error message.
            (read_expr_low_mem_phase1): Likewise.
            (read_debug_info): Add die_offset to error messages for unknown
            forms, attributes extending beyond end of CU or unknown block
            form attributes.

    https://sourceware.org/bugzilla/show_bug.cgi?id=27363

commit 4705796eb538761db37d5e4ef42171f08c394a65
Author: Mark Wielaard <mark@klomp.org>
Date:   Tue Jan 26 21:12:18 2021 +0100

    Add DIE offsets in error messages to make it easier to find what is wrong.

    With the following patch dwz will give a message like:

    libmozjs-78.so: Couldn't find DIE at [bd6b507] referenced by
      DW_AT_abstract_origin from DIE at [bd5bb9b]

    Which makes it a easier to figure out what is going on.

    In the above case you can simply lookup the producer of the CU for those
    two DIEs. Which turned out the be "clang LLVM (rustc version 1.49.0)"
    which seems to have gotten the abstract origin reference wrong.

            * dwz.c (read_exprloc): Add DIE offsets to error messages.
            (checksum_die): Likewise.

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[Bug default/27363] Emit more detailed diagnostic output for "Unknown DWARF"

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27363

--- Comment #2 from Mark Wielaard <mark at klomp dot org> ---
For some reason I added commit 2 from comment #1 but not commit 1.
I have done so now:

commit beca0b4f1423f97f7a2da74a45f9f86d401e4ad2
Author: Mark Wielaard <mark@klomp.org>
Date:   Sun Feb 21 16:55:17 2021 +0100

    Print abbrev or DIE offset for Unknown DWARF error message.

            * dwz.c (read_abbrev): Add .debug_abbrev offset to error message.
            (read_exprloc): Print DIE offset that referenced the unknown
            operand in error message.
            (read_expr_low_mem_phase1): Likewise.
            (read_debug_info): Add die_offset to error messages for unknown
            forms, attributes extending beyond end of CU or unknown block
            form attributes.

    https://sourceware.org/bugzilla/show_bug.cgi?id=27363

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