[Bug bootstrap/55051] [4.8 Regression] profiledbootstrap failed

["tejohnson at google dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55051

--- Comment #28 from Teresa Johnson <tejohnson at google dot com> 2012-11-16 18:03:08 UTC ---
On Fri, Nov 16, 2012 at 9:42 AM, hubicka at gcc dot gnu.org
<gcc-bugzilla@gcc.gnu.org> wrote:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55051
>
> --- Comment #27 from Jan Hubicka <hubicka at gcc dot gnu.org> 2012-11-16 17:42:26 UTC ---
>   /* Now merge each file.  */
>   for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
>     {
>         // Open existing gcda file for gi_ptr
>         // Find program summary corresponding to this executable -> save in prg
>         // Merge execution counts for each function
>         // Merge program summary
>         //      - If this is the first merged file for this execution,
> save merged summary in all_prg
>         //      - Otherwise if #runs the same in prg and all_prg,
> print error message if prg != all_prg.
>         // Write merged gcda
>     }
>
> Hmm, yes, it seems wrong.  We can not expect all gcda files to have same number
> of runs.  We really need to process sum_all & friends locally for each file.
> Only I suppose we can check if number of runs of the prg happens to match the
> last merged file then sum_all should match.

I'm confused - that is essentially what it is doing today (although
comparing against the first merged file instead of the last merged
file). It isn't expecting all the gcda files to have the same number
of runs, but when they do it expects them to have the same sum_all.
See the trace of updates I show below this pseudo code in the same
email that shows why that is not working.

> That would be nice consistency
> check. If the bootstrap works with this change, consider the patch preapproved.

I had sent a patch last night to simply rip out this check based on
the analysis I had done, but I assume you are not talking about that.

Thanks,
Teresa

>
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Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413