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From: "glisse at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/58806] New attribute for functions that access memory only through their arguments Date: Mon, 21 Oct 2013 02:14:00 -0000 [thread overview] Message-ID: <bug-58806-4-Jk8lgWrF2I@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-58806-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58806 --- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> --- struct A { int i; double d; }; void g(double*); void f(){ A a; a.i=1; g(&a.d); if(a.i != 1) __builtin_abort(); } Here, I guess g is allowed to take its argument, cast it to char*, subtract offsetof(struct A, d), cast to A* and go modify ->i of that? It would be convenient to have a way to promise that g does no such thing, but that looks like a different type of promise than the one in comment #0. The example is derived from the use of a temporary object of a reference-counted type, where ideally all uses of the counter should disappear and the code be equivalent to: double d; g(&d);
next parent reply other threads:[~2013-10-21 2:14 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-58806-4@http.gcc.gnu.org/bugzilla/> 2013-10-21 2:14 ` glisse at gcc dot gnu.org [this message] 2013-10-21 8:34 ` rguenth at gcc dot gnu.org 2013-10-22 11:32 ` glisse at gcc dot gnu.org 2013-10-22 14:58 ` glisse at gcc dot gnu.org 2013-10-22 20:27 ` glisse at gcc dot gnu.org 2024-04-09 3:51 ` pinskia at gcc dot gnu.org
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