[Bug symtab/15035] New: Excessive symtab expansion setting a breakpoint on foo::bar.

[Bug symtab/15035] New: Excessive symtab expansion setting a breakpoint on foo::bar.

[dje at google dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15035

             Bug #: 15035
           Summary: Excessive symtab expansion setting a breakpoint on
                    foo::bar.
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: symtab
        AssignedTo: unassigned@sourceware.org
        ReportedBy: dje@google.com
    Classification: Unclassified


I haven't looked into the psymtab side, but when using .gdb_index and doing

(gdb) b (anonymous namespace)::foo

gdb will first expand every CU/TU (dwarf) that defines anonymous namespace, and
only after that will it look for foo.
However, the symbol table in .gdb_index has an entry for (anonymous
namespace)::foo. The data is there to tell gdb precisely which CUs to expand.
Seems like the index isn't being fully utilitized here.

In a large app there could be 2k such CUs (or more), and setting a breakpoint
takes way too long (long enough that I give up after a minute and haven't put
in the effort to compute the actual number).

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[Bug symtab/15035] Excessive symtab expansion setting a breakpoint on foo::bar.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=15035

Tom Tromey <tromey at sourceware dot org> changed:

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

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
Both linespec and the parsers should probably try maximal
lookups as opposed to minimal lookups.  That is, for
"x::y::z", they should start with the full string.  Then
if needed (?) they could try prefixes.

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[Bug symtab/15035] Excessive symtab expansion setting a breakpoint on foo::bar.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=15035

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
For C++ I wonder if there's a case where a maximal lookup
could even "fail", in the sense that a prefix would succeed
instead.

For languages like Ada this can happen because "x.y.z" may
refer to some field "z" of a record "x.y".  But in C++
this would be "x::y.z" instead.

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