https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108552
--- Comment #46 from rguenther at suse dot de <rguenther at suse dot de> --- On Mon, 30 Jan 2023, jakub at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108552 > > --- Comment #44 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > I guess we should try and see. > For volatile, > --- gcc/coverage.cc 2023-01-02 09:32:37.078072992 +0100 > +++ gcc/coverage.cc 2023-01-30 09:24:45.219951352 +0100 > @@ -774,6 +774,7 @@ build_var (tree fn_decl, tree type, int > TREE_STATIC (var) = 1; > TREE_ADDRESSABLE (var) = 1; > DECL_NONALIASED (var) = 1; > + TREE_THIS_VOLATILE (var) = 1; > SET_DECL_ALIGN (var, TYPE_ALIGN (type)); > > return var; > > would do it I think (but it should be conditional on new -fupdate-profile > modes, single-volatile and prefer-atomic-volatile or something similar). > Or perhaps insert asm volatile ("" : "+g" (tmp)); in between the load and > store > and see how that compares to the volatile vars? Or adding another flag on the > gcov vars next to DECL_NONALIASED and just avoid specific optimizations on it > that somebody runs into (not as reliable but could be faster) - for now > hoisting in LIM and sinking. We could put an __attribute__(("semi atomic")) on them ... it all somewhat feels like a hack. We could make half of the update volatile only, like only make the store volatile, not the read?
