[Bug symtab/31010] New: Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[Bug symtab/31010] New: Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[josh.cottingham at linaro dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

            Bug ID: 31010
           Summary: Evaluating "mixed-cased" fundamental types causes
                    hangs/OOM due to full symtab expansion
           Product: gdb
           Version: 13.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: josh.cottingham at linaro dot org
  Target Milestone: ---

Attempting to evaluate "mixed/uper-case" C/C++ fundamental types (such as
"output LONG" or "output Int") will cause GDB to try to fully expand the whole
symbol table. Depending on how large the binary we are debugging, this could
cause GDB to hang for several minutes and has been observed to cause
Out-of-Memory issues on some circumstances.

Via a git bisect, it was observed that this regression first occurs on the
commit which enables the new DWARF indexer:
https://sourceware.org/pipermail/gdb-patches/2022-April/187417.html

Easiest way to reproduce this issue is to attempt to run GDB on a debug build
of GDB:

$ gdb ./gdb/gdb
(gdb) start
Temporary breakpoint 1 at 0x410675: file gdb.c, line 28.
Starting program: /path/to/binutils-gdb/gdb/gdb 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Temporary breakpoint 1, main (argc=1, argv=0x7fffffffd578) at gdb.c:28
28        memset (&args, 0, sizeof args);
(gdb) output LONG
No symbol "LONG" in current context.

This will take ~20-30 seconds, though as stated above with larger binaries it
has been observed to take make longer or cause Out-of-Memory. Worth noting the
hang does not occur if we attempt to output other non-existent symbols such as
"output NOTREAL".

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[Bug symtab/31010] Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[josh.cottingham at linaro dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

Josh Cottingham <josh.cottingham at linaro dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P2                          |P1
                 CC|                            |josh.cottingham at linaro dot org

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[Bug symtab/31010] Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sam at gentoo dot org,
                   |                            |tromey at sourceware dot org

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[Bug symtab/31010] Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
cooked_index_functions::expand_symtabs_matching defers to the
index, which uses case-insensitive lookup to handle things like
Ada and Fortran.

This probably needs some refinement.
Maybe a lookup_name ought to carry a language along with it.

Anyway more filtering could be done in the inner loop of that
function.

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[Bug symtab/31010] Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |29366


Referenced Bugs:

https://sourceware.org/bugzilla/show_bug.cgi?id=29366
[Bug 29366] [meta] New DWARF indexer meta bug
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[Bug symtab/31010] Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=30520

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[Bug symtab/31010] Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

Tom Tromey <tromey at sourceware dot org> changed:

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

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
Closing this as a dup, since it seems to be basically the
same problem as the other bug, and that bug has a patch.
Worth noting that this problem is reported as being fixed
by that patch as well.

*** This bug has been marked as a duplicate of bug 30520 ***

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