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From: Eric Botcazou <ebotcazou@libertysurf.fr> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, Subject: Re: optimization/7799: [3.2/3.3 regression] Loop bug with optimization flag -Os in gcc Date: Fri, 13 Dec 2002 05:56:00 -0000 [thread overview] Message-ID: <20021213135602.24626.qmail@sources.redhat.com> (raw) The following reply was made to PR optimization/7799; it has been noted by GNATS. From: Eric Botcazou <ebotcazou@libertysurf.fr> To: "Christian Ehrhardt" <ehrhardt@mathematik.uni-ulm.de> Cc: nejataydin@superonline.com, gcc-gnats@gcc.gnu.org, gcc@gcc.gnu.org, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org Subject: Re: optimization/7799: [3.2/3.3 regression] Loop bug with optimization flag -Os in gcc Date: Fri, 13 Dec 2002 14:49:01 +0100 > This transformation is IMHO illegal because there is no way to make the > comparison in general equivialent to that in the original for loop. > If p is initially 0x7ffffffc the comparison must be treated as unsigned= , > however, if p is initially 0xfffffffc the comparison must be treated as > signed. Well-known deficiency of the strength reduction pass (see the testcase=20 testsuite/gcc.c-torture/execute/loop-2e.c which is XFAILed on x86 at -Os)= =2E --=20 Eric Botcazou
next reply other threads:[~2002-12-13 13:56 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-12-13 5:56 Eric Botcazou [this message] -- strict thread matches above, loose matches on Subject: below -- 2002-12-20 16:36 Robert Dewar 2002-12-20 1:26 Christian Ehrhardt 2002-12-19 22:16 Joern Rennecke 2002-12-19 19:26 Segher Boessenkool 2002-12-13 10:06 Eric Botcazou 2002-12-13 6:56 Christian Ehrhardt 2002-12-13 5:46 Christian Ehrhardt 2002-12-06 12:52 bangerth
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