[Bug symtab/29572] New: [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[Bug symtab/29572] New: [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

            Bug ID: 29572
           Summary: [gdb/symtab] read.h:298: internal-error: length:
                    Assertion `m_length != 0' failed.
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

When running with target board cc-with-debug-names, I run into:
...
FAIL: gdb.dwarf2/dw2-symtab-includes-lookup.exp: ptype myint (GDB internal
error)
FAIL: gdb.dwarf2/enqueued-cu-base-addr.exp: ptype foo (GDB internal error)
FAIL: gdb.dwarf2/enqueued-cu-base-addr.exp: CU addr found
FAIL: gdb.dwarf2/opaque-type-lookup.exp: p variable_a (GDB internal error)
FAIL: gdb.dwarf2/opaque-type-lookup.exp: p variable_b (GDB internal error)
FAIL: gdb.dwarf2/varval.exp: print bad_die_val1 (GDB internal error)
...

Command-line reproducer of first fail:
...
$ gdb -q -batch
./outputs/gdb.dwarf2/dw2-symtab-includes-lookup/dw2-symtab-includes-lookup -ex
"ptype myint"
/home/vries/gdb_versions/devel/src/gdb/dwarf2/read.h:298: internal-error:
length: Assertion `m_length != 0' failed.
...

We're trying to find (in dwarf2_find_containing_comp_unit) the containing CU
for DIE 0xa5:
...
  Compilation Unit @ offset 0x9a:
   Length:        0x16 (32-bit)
   Version:       4
   Abbrev Offset: 0x5a
   Pointer Size:  8
 <0><a5>: Abbrev Number: 2 (DW_TAG_partial_unit)
    <a6>   DW_AT_stmt_list   : 0xe8
 <1><aa>: Abbrev Number: 3 (DW_TAG_base_type)
    <ab>   DW_AT_byte_size   : 4
    <ac>   DW_AT_encoding    : 5        (signed)
    <ad>   DW_AT_name        : myint
 <1><b3>: Abbrev Number: 0
...
which is 0x9a, but when getting the length of the unit, it turns out to be 0.

This is a regression since commit 1c04f72368c ("[gdb/symtab] Fix assert in
set_length"), which starting keeping length at 0 when reading the CU list from
.debug_names, and relied on a later set_length to fill in the actual length.

This happens fine for CUs, but in this case it's a PU.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
Backtrace at assert:
...
(gdb) bt
#0  __GI_raise (sig=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  0x00007ffff4a05375 in __GI_abort () at abort.c:79
#2  0x0000000000c81e49 in dump_core ()
    at /home/vries/gdb_versions/devel/src/gdb/utils.c:202
#3  0x0000000000c8247f in internal_vproblem(internal_problem *, const char *,
int, const char *, typedef __va_list_tag __va_list_tag *) (
    problem=0x2785c60 <internal_error_problem>, 
    file=0x14cf880 "/home/vries/gdb_versions/devel/src/gdb/dwarf2/read.h", 
    line=298, fmt=0x14cf850 "%s: Assertion `%s' failed.", ap=0x7fffffff90e8)
    at /home/vries/gdb_versions/devel/src/gdb/utils.c:450
#4  0x0000000000c82555 in internal_verror (
    file=0x14cf880 "/home/vries/gdb_versions/devel/src/gdb/dwarf2/read.h", 
    line=298, fmt=0x14cf850 "%s: Assertion `%s' failed.", ap=0x7fffffff90e8)
    at /home/vries/gdb_versions/devel/src/gdb/utils.c:476
#5  0x00000000013cef2f in internal_error (
    file=0x14cf880 "/home/vries/gdb_versions/devel/src/gdb/dwarf2/read.h", 
    line=298, fmt=0x14cf850 "%s: Assertion `%s' failed.")
    at /home/vries/gdb_versions/devel/src/gdbsupport/errors.cc:58
#6  0x00000000006b1b37 in dwarf2_per_cu_data::length (this=0x369e3a0)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.h:298
#7  0x00000000007121d2 in dwarf2_find_containing_comp_unit (
    sect_off=(unknown: 0xa5), offset_in_dwz=0, 
    all_comp_units=std::vector of length 9, capacity 9 = {...})
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:23558
#8  0x0000000000712280 in dwarf2_find_containing_comp_unit (
    sect_off=(unknown: 0xa5), offset_in_dwz=0, per_bfd=0x369cf80)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:23576
#9  0x00000000006ec16b in process_imported_unit_die (die=0x36bdc50,
cu=0x2d26d00)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:8577
#10 0x00000000006ec6c8 in process_die (die=0x36bdc50, cu=0x2d26d00)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:8735
#11 0x00000000006ee4f4 in read_file_scope (die=0x36bdb50, cu=0x2d26d00)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:9642
#12 0x00000000006ec448 in process_die (die=0x36bdb50, cu=0x2d26d00)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:8643
#13 0x00000000006ebbcc in process_full_comp_unit (cu=0x2d26d00, 
    pretend_language=language_minimal)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:8412
#14 0x00000000006e91f6 in process_queue (per_objfile=0x2d28540)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:7658
#15 0x00000000006db090 in dw2_do_instantiate_symtab (per_cu=0x369e420, 
    per_objfile=0x2d28540, skip_partial=false)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:2063
#16 0x00000000006db139 in dw2_instantiate_symtab (per_cu=0x369e420, 
    per_objfile=0x2d28540, skip_partial=false)
    at /home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:2085
...

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14335
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14335&action=edit
Demonstrator patch

This is an alternative way of fixing PR29453.

Basically, we look into the CU header to find the length.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #2)
> Created attachment 14335 [details]
> Demonstrator patch
> 
> This is an alternative way of fixing PR29453.
> 
> Basically, we look into the CU header to find the length.

The more intrusive, but more maintainable version of this would be to just
always call create_all_comp_units, not just for readnow and cooked index, but
also for .debug_names and .gdb_index.

Tom, I think you suggested that already somewhere.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #3)
> (In reply to Tom de Vries from comment #2)
> > Created attachment 14335 [details]
> > Demonstrator patch
> > 
> > This is an alternative way of fixing PR29453.
> > 
> > Basically, we look into the CU header to find the length.
> 
> The more intrusive, but more maintainable version of this would be to just
> always call create_all_comp_units, not just for readnow and cooked index,
> but also for .debug_names and .gdb_index.
> 
> Tom, I think you suggested that already somewhere.

Hmm, this also provides us with an opportunity to fix PR25969.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14336
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14336&action=edit
Tentative patch

Currently testing

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #5)
> Created attachment 14336 [details]
> Tentative patch
> 
> Currently testing

Hmm, I guess I'll need to give create_signatured_type_table_from_debug_names
the same treatment as create_cus_from_debug_names, that is, transform it into
check_signatured_type_table_from_debug_names.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #5)
> Created attachment 14336 [details]
> Tentative patch
> 
> Currently testing

Testing went fine (native + target board cc-with-debug-names), so I suppose
it's just a question of adding the TU handling bit.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #8 from Tom de Vries <vries at gcc dot gnu.org> ---
Fix was submitted here:
https://sourceware.org/pipermail/gdb-patches/2022-September/192031.html

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #9 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=107ab8d45df84b442ce2d79c6dda3a9b3afc80d5

commit 107ab8d45df84b442ce2d79c6dda3a9b3afc80d5
Author: Tom de Vries <tdevries@suse.de>
Date:   Thu Aug 10 15:46:30 2023 +0200

    [gdb/testsuite] Improve failure mode in
gdb.dwarf2/enqueued-cu-base-addr.exp

    I ran test-case gdb.dwarf2/enqueued-cu-base-addr.exp with target board
    cc-with-debug-names, and ran into:
    ...
    FAIL: gdb.dwarf2/enqueued-cu-base-addr.exp: ptype foo (GDB internal error)
    FAIL: gdb.dwarf2/enqueued-cu-base-addr.exp: CU addr found
    ...

    The first FAIL is a known issue, PR symtab/29572.

    The following FAIL is a consequence of the first FAIL, so require for the
    second test that the first test passes.

    Tested on x86_64-linux, with target boards unix and cc-with-debug-names.

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

--- Comment #10 from Sourceware Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b17ef9dcd8d16eedf4e60565cd7701698b5a0b6b

commit b17ef9dcd8d16eedf4e60565cd7701698b5a0b6b
Author: Tom de Vries via Gdb-patches <gdb-patches@sourceware.org>
Date:   Wed Dec 6 10:29:17 2023 +0100

    [gdb/symtab] Redo "Fix assert in set_length"

    This reverts commit 1c04f72368c ("[gdb/symtab] Fix assert in set_length"),
due
    to a regression reported in PR29572, and implements a different fix for
PR29453.

    The fix is to not use the CU table in a .debug_names section to construct
    all_units, but instead use create_all_units, and then verify the CU
    table from .debug_names.  This also fixes PR25969, so remove the KFAIL.

    Approved-By: Tom Tromey <tom@tromey.com>

    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29572
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=25969

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[Bug symtab/29572] [gdb/symtab] read.h:298: internal-error: length: Assertion `m_length != 0' failed.

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29572

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |15.1

--- Comment #11 from Tom de Vries <vries at gcc dot gnu.org> ---
Fixed.

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