https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108552
--- Comment #40 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #39)
> I was wonering if we should not provide flag to turn all counts
> volatile. That way we will still have race conditions on their updates
> (and it would be chepaer than atomic) but we won't run into such wrong
> code issues nor large profile mismatches.
Yes, see above. Or a mode in which we would just avoid hoisting and sinking
the gcov vars but keep them non-volatile. Or both.
But I guess it would be nice to get Vlad's patch into trunk and release
branches for now (perhaps with an extra check for startswith "__gcov" on
DECL_NAME, so that we don't do it for the Fortran tokens).
As for the patch, just small nits, I think get_base_address returns always
non-NULL, so it could be
if (tree expr = MEM_EXPR (res))
{
expr = get_base_address (expr);
if (VAR_P (expr)
&& DECL_NONALIASED (expr)
&& DECL_NAME (expr))
{
const char *name = IDENTIFIER_POINTER (DECL_NAME (expr));
/* Don't reread coverage counters from memory, if single
update model is used in threaded code, other threads
could change the counters concurrently. See PR108552. */
if (startswith (name, "__gcov"))
return x;
}
}
