http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46941
--- Comment #13 from Patrick Marlier <patrick.marlier at gmail dot com> 2011-02-04 20:13:04 UTC --- Hi Aldy, On Fri, Feb 4, 2011 at 7:40 PM, aldyh at gcc dot gnu.org < gcc-bugzi...@gcc.gnu.org> wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46941 > > --- Comment #12 from Aldy Hernandez <aldyh at gcc dot gnu.org> 2011-02-04 > 18:40:09 UTC --- > Patrick, the reason memory allocated by the C++ new operator does not get > optimized by the TM-memopt pass is not because of a missing ECF_MALLOC > attribute, but because the alias oracle in GCC considers the chunk of > memory as > possibly able to escape from the current function. > > I have added the "malloc" attribute to the declaration of the new operator and it worked so I though this was it. After this I found a discussion about adding malloc attribute to new operator... > That is, the following hunk of code returns true in the TM-memopt pass: > > if (ptr_deref_may_alias_global_p (x)) > > Apparently, since new/delete operators may be overridden by class specific > hooks, the memory must be considered escaped. > Hum I see. But if the new/delete operators are not overridden then the returned memory could be marked as transaction local, right? Otherwise at least a comment somewhere is welcome to be aware of this behavior. > So, this is not a TM bug, but a "feature" of the alias oracle in GCC. Actually, this was not a bug but an improvement (why using costly write barriers on transaction local memory). As usual, thanks ;) Patrick.
