[Bug gcov/profile/28441] Need atomic increment of gcov counters for MP programs

["seongbae dot park at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #5 from seongbae dot park at gmail dot com  2006-07-23 17:27 -------
It seems that you didn't change libgcov.c,
which suggests that you didn't address __gcov_{pow2,interval}_profiler.
Without such change, -fprofile-generate will cause the mismatch between
the value counters and edge counters, 
so it would be very nice if you can fix that as well 
(this is just a suggestion).

In case someone wants to address that issue,
I think there are three choices:

#1 make above profiler routines to use atomic increment *always*
#2 introduce a new environment variable to pick atomic/non-atomic increment
#3 make atomic increment version of those routines and -fprofile-multithread to
generate codes to call them.

I prefer #3, but #1 might be simple enough without much bad affect.

Another comment is about the name of -fprofile-multithread.
There's an alternative MT-safe profiling scheme of making counters TLS.
So I'd prefer if the option for atomic increment is more explicit, 
something like -fprofile-atomic-increment.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28441