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From: "aoliva at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/42631] [4.5 Regression] "-fcompare-debug failure" with "-O1 -funroll-loops"
Date: Fri, 08 Jan 2010 02:44:00 -0000	[thread overview]
Message-ID: <20100108024347.5276.qmail@sourceware.org> (raw)
In-Reply-To: <bug-42631-14164@http.gcc.gnu.org/bugzilla/>



------- Comment #10 from aoliva at gcc dot gnu dot org  2010-01-08 02:43 -------
Well, it's not like accessing an uninitialized variable is well-defined, so
it's not like our splitting into multiple webs is wrong, or could possibly
generate incorrect results.  The only reason we notice this is that it gets us
different results precisely for a test framework designed to be picky about
minute differences, even if in the end they don't make any difference in terms
of program behavior.

Just to be clear, although the references were *originally* part of a loop,
when the loop was unrolled, the failing bits became part of an pre-loop block,
so there's nothing that could actually fail here in terms of codegen, AFAICT.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42631


  parent reply	other threads:[~2010-01-08  2:44 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-06  0:50 [Bug debug/42631] New: " zsojka at seznam dot cz
2010-01-06 12:00 ` [Bug rtl-optimization/42631] [4.5 Regression] " rguenth at gcc dot gnu dot org
2010-01-06 12:33 ` steven at gcc dot gnu dot org
2010-01-06 23:48 ` steven at gcc dot gnu dot org
2010-01-06 23:54 ` steven at gcc dot gnu dot org
2010-01-07 13:54 ` aoliva at gcc dot gnu dot org
2010-01-07 14:54 ` rguenth at gcc dot gnu dot org
2010-01-07 19:55 ` steven at gcc dot gnu dot org
2010-01-07 20:44 ` aoliva at gcc dot gnu dot org
2010-01-08  1:01 ` aoliva at gcc dot gnu dot org
2010-01-08  1:27 ` aoliva at gcc dot gnu dot org
2010-01-08  1:56 ` zadeck at naturalbridge dot com
2010-01-08  2:44 ` aoliva at gcc dot gnu dot org [this message]
2010-01-08  3:52 ` zadeck at naturalbridge dot com
2010-01-08  5:27 ` aoliva at gcc dot gnu dot org
2010-01-09 14:42 ` aoliva at gcc dot gnu dot org
2010-01-09 14:50 ` aoliva at gcc dot gnu dot org
     [not found] <bug-42631-4@http.gcc.gnu.org/bugzilla/>
2011-02-05 12:06 ` jiez at gcc dot gnu.org
2011-02-10  4:23 ` jiez at gcc dot gnu.org

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