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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/53805] combine_comparisons changes trapping behavior
Date: Fri, 29 Jun 2012 14:34:00 -0000 [thread overview]
Message-ID: <bug-53805-4-7MB62valtv@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-53805-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53805
--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-29 14:34:08 UTC ---
(In reply to comment #4)
> On Fri, 29 Jun 2012, rguenth at gcc dot gnu.org wrote:
>
> > We do not try to preserve traps instead we only try to not produce new ones.
>
> That's a bug. -ftrapping-math should do both (as regards the set of
> exceptions raised between function calls or asms that might test them, not
> necessarily preserving the exact positive number of times an exception is
> raised). If that's thought to be a performance issue maybe it should be
> split into separate options for the two cases.
We happily remove dead trapping statements:
void foo(double x, int y)
{
1 / x;
1 / y;
}
Eric recently (for the sake of Java) added fdelete-dead-exceptions (in Ada,
with -fnon-call-exceptions, you are allowed to remove the above statements).
We similarly happily remove dead indirect loads (that might trap).
I think it is preferable that we do all this, we can't always reasonably
prove that a path in the CFG is never reached.
next prev parent reply other threads:[~2012-06-29 14:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 11:00 [Bug tree-optimization/53805] New: " glisse at gcc dot gnu.org
2012-06-29 12:02 ` [Bug tree-optimization/53805] " rguenth at gcc dot gnu.org
2012-06-29 12:19 ` glisse at gcc dot gnu.org
2012-06-29 12:22 ` rguenth at gcc dot gnu.org
2012-06-29 14:24 ` joseph at codesourcery dot com
2012-06-29 14:34 ` rguenth at gcc dot gnu.org [this message]
2012-06-29 14:43 ` joseph at codesourcery dot com
2012-06-29 14:54 ` rguenth at gcc dot gnu.org
2012-07-02 7:27 ` jakub at gcc dot gnu.org
2012-07-06 21:53 ` glisse at gcc dot gnu.org
2012-08-02 19:55 ` glisse at gcc dot gnu.org
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