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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/53805] combine_comparisons changes trapping behavior
Date: Fri, 29 Jun 2012 12:19:00 -0000 [thread overview]
Message-ID: <bug-53805-4-CS9137xIJb@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 #2 from Marc Glisse <glisse at gcc dot gnu.org> 2012-06-29 12:19:07 UTC ---
(In reply to comment #1)
> We do not try to preserve traps instead we only try to not produce new ones.
That would make a lot of sense, and assuming it is the official policy I am
happy to learn that, but then why don't we optimize this testcase:
int f(double a,double b){
if(a>=b) if(a<=b) return 1;
return 0;
}
to
if(a==b) return 1;
?
The test in combine_comparisons seems to deliberately check for any change of
the trapping condition, not just false->true.
I am happy to relabel this bug (or file a new one if you prefer) as a missed
optimization.
next prev parent reply other threads:[~2012-06-29 12:19 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 [this message]
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
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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