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From: Eric Botcazou <ebotcazou@libertysurf.fr>
Subject: Re: optimization/7799: [3.2/3.3 regression] Loop bug with optimization flag -Os in gcc
Reply-To: Eric Botcazou <ebotcazou@libertysurf.fr>
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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