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[Bug rtl-optimization/19210] [4.0 Regression] not using do-loop for some loops
- From: "giovannibajo at libero dot it" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 31 Dec 2004 00:49:54 -0000
- Subject: [Bug rtl-optimization/19210] [4.0 Regression] not using do-loop for some loops
- References: <20041230204442.19210.pinskia@gcc.gnu.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From giovannibajo at libero dot it 2004-12-31 00:49 -------
Zdenek, I have troubles understanding how such a loop can ever be infinite:
- if wrapv, sooner or later K will reach any N (and thus, surely it will become
less or equal to any given N).
- if nowrapv, my understanding is that all bets are off: if f() is called with
N<=3 the loop will terminate, otherwise it's undefined behaviour. In such a
situation, we can still perform doloop because it's not going to screw the
program any more than it is already.
What am I missing?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19210