[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 #23 from Teresa Johnson <tejohnson at google dot com> 2012-11-15 06:44:00 UTC ---
On Wed, Nov 14, 2012 at 5:17 PM, hubicka at gcc dot gnu.org
<gcc-bugzilla@gcc.gnu.org> wrote:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55051
>
> --- Comment #16 from Jan Hubicka <hubicka at gcc dot gnu.org> 2012-11-15 01:17:43 UTC ---
> Theresa: I am using gcc10 from compilation farm, but I think it is fairly
> universal problem.
> Also I think that gcc_assert should not be assert, but an user readable error
> about gcov file corruption.

I took a look at this some more this evening, printing out the values
being compared. Note that the modification I made to this code was to
ignore the histogram when comparing the gcov_ctr_summary, since the
order of update can affect the merged histogram values as they are
prorated. So essentially we are doing the same comparison here that we
did before the histogram was added.

I found that the gcov_ctr_summary fields being compared are identical
except for the sum_all, which is different, leading to the error
message. The number of counters, run_max and sum_max are the same. I'm
not sure how that can happen given that locking is on and the sum_all
should be the same regardless of the merging order.

Note though that this is not an assert. It just emits a message to
stderr. Do you think a better error message is appropriate? I'm not
sure the "some data files may have been removed" is an accurate
description of the issue. Perhaps something like "Profile data file
mismatch may indicate corrupt profile data"?

Teresa

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