Re: [PATCH 1/4] Attribute method inlining

[Pedro Alves <palves@redhat.com>]

On 5/21/20 2:08 AM, Hannes Domani via Gdb-patches wrote:
>  Am Mittwoch, 20. Mai 2020, 19:40:44 MESZ hat Tom Tromey <tromey@adacore.com> Folgendes geschrieben:
> 
>> I ran gdb 10 times like:
>>
>>        /bin/time -f %e \
>>              ./gdb/gdb --data-directory ./gdb/data-directory -nx \
>>              -iex 'set debug-file-directory /usr/lib/debug' \
>>              -batch $X
>>
>> ... where $X was the test executable.  Then I computed the mean time.
>> This was all done with a standard (-g -O2) build of gdb.
>>
>> The baseline times were
>>
>> gdb    1.90
>> libxul 2.12
>> Ada    2.61
>>
>> This patch brings the numbers down to
>>
>> gdb    1.88
>> libxul 2.11
>> Ada    2.60
> 
> When I saw this, I thought I could do a similar profiling test on Windows (but
> only with gdb itself).
> 
> So just: gdb.exe -q -batch gdb.exe
> 
> And I was a bit suprised to see that strcmp_iw_ordered (called from
> sort_pst_symbols -> std::sort) is in ~24% of the profiling samples.
> And only because of the functions isspace and tolower.
> 
> So I made a simple test, and added this before strcmp_iw_ordered:
> 
> static inline int isspace2 (int c)
> {
>   return c == 0x20 || (c >= 0x09 && c <= 0x0d);
> }
> #define isspace isspace2
> 
> static inline int tolower2 (int c)
> {
>   return (c >= 'A' && c <= 'Z') ? c + 0x20 : c;
> }
> #define tolower tolower2
> 
> And the mean time went from 3.7s down to 2.7s.
> 
> 
> I'm not saying this is a correct solution, but does strcmp_iw_ordered have to
> support anything besides the "C" locale?
> 
> Also, are isspace and tolower only on Windows a bottleneck?
> 
> (If anyone wants to see them, I can provide some profiler flame-graphs)

There was a patch for this not that long ago.  Let me try to dig it up.

Thanks,
Pedro Alves