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From: "matz at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/40194] fortran rules for optimizing Date: Thu, 13 Aug 2009 12:16:00 -0000 [thread overview] Message-ID: <20090813121617.4421.qmail@sourceware.org> (raw) In-Reply-To: <bug-40194-6642@http.gcc.gnu.org/bugzilla/> ------- Comment #9 from matz at gcc dot gnu dot org 2009-08-13 12:16 ------- It is indeed somewhat related, but currently the patchset doesn't help here. The first issue is, that I create new types with unconflicting alias sets only for global variables, not local ones (as I1 is in this case). I believe I can change this meanwhile (the restriction came from earlier versions of the patch). But even if this is fixed we can't figure out the difference between INTENT(IN) and INTENT(OUT), i.e. even then we still believe that I1 can possibly be changed by the call. We have three ways out of this: 1) make the frontend not pass INTENT(IN) parameters by reference, maybe at least for scalars. That would be the preferred way, but unfortunately this probably would break a lot of code assuming such calling convention especially when interfacing with C code :-/ 2) invent a new attribute that we can attach to the individual arguments that would indicate non-clobbering via this reference 3) find a combination of existing things (DECL_BY_REFERENCE/TREE_READONLY/etc) that could be used by the middle end to conclude non-clobbering. Something like a const reference comes to mind, but unfortunately (the middle-end coming mostly from the C/C++ side) we don't conclude many interesting things about const refs/pointers. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40194
next prev parent reply other threads:[~2009-08-13 12:16 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-05-19 9:59 [Bug middle-end/40194] New: " jv244 at cam dot ac dot uk 2009-05-19 10:01 ` [Bug middle-end/40194] " jv244 at cam dot ac dot uk 2009-05-19 10:14 ` jv244 at cam dot ac dot uk 2009-05-19 10:20 ` rguenth at gcc dot gnu dot org 2009-05-19 10:40 ` rguenth at gcc dot gnu dot org 2009-05-19 11:55 ` jv244 at cam dot ac dot uk 2009-05-19 12:04 ` rguenth at gcc dot gnu dot org 2009-05-19 12:11 ` rguenth at gcc dot gnu dot org 2009-08-13 7:23 ` jv244 at cam dot ac dot uk 2009-08-13 12:16 ` matz at gcc dot gnu dot org [this message] [not found] <bug-40194-4@http.gcc.gnu.org/bugzilla/> 2012-06-29 14:14 ` Joost.VandeVondele at mat dot ethz.ch 2013-03-29 9:07 ` Joost.VandeVondele at mat dot ethz.ch
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