Re: [RFA] massively speed up "info var foo" on large programs

[Doug Evans <dje at google dot com>]

Ping.
I'm happy with this patch enough to check it in in a few days if there
are no objections.
[Note that the "interesting" case only comes up when a PLT entry
refers to a function that isn't present in any objfile.  If it is
present in another objfile then it will be printed there.]

On Sun, May 27, 2012 at 9:49 PM, Doug Evans <dje@google.com> wrote:
> On Fri, May 25, 2012 at 1:50 AM, Pedro Alves <palves@redhat.com> wrote:
>> On 05/25/2012 09:21 AM, Doug Evans wrote:
>>
>>>
>>> The output is different from the previous code, I didn't take into
>>> account the symbols that gdb creates for @plt entries. ?I think if we
>>> want to continue to provide the current output, we should add an
>>> option to "info var|fun|type" to produce it: the normal case shouldn't
>>> be that slow.
>>
>>
>> Different how? ?The patch has no testsuite updates, so the email reader is
>> left wondering. ?;-)
>
> In the "Non-debugging symbols" section of the output, when a symbol
> would have been found in another objfile, the code would have not
> printed the non-@plt form of the function name.
> With this patch we have a decision to make. ?Searching all the other
> objfiles is not reasonable (IMO) so what to do? ?I can think of two
> possibilities: always print it or never print it. ?Since the symbol in
> question is an artificial symbol created by gdb I have opted for never
> printing it.
>
> Thus instead of seeing this in the "Non-debugging symbols" section of
> the output:
>
> 0x1234 foo@plt
> 0x1234 foo
>
> the output will contain:
>
> 0x1234 foo@plt
>
> Here is v3 of the patch. ?I added a testcase.
> Regression tested on amd64-linux.
>
> Ok to check in?
>
> 2012-05-27 ?Doug Evans ?<dje@google.com>
>
> ? ? ? ?* symtab.c (minimal_symbol): New member created_by_gdb.
> ? ? ? ?* elfread.c (elf_symtab_read): Set created_by_gdb for @plt
> minsym
> ? ? ? ?created by gdb.
> ? ? ? ?* symtab.c (lookup_msymbol_in_objfile): New function.
> ? ? ? ?(search_symbols): Call it. ?Only scan minsyms if nfiles == 0.
>
> ? ? ? ?testsuite:
> ? ? ? ?* gdb.base/info-fun.exp: New file.
> ? ? ? ?* gdb.base/info-fun.c: New file.
> ? ? ? ?* gdb.base/info-fun-solib.c: New file.