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From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/30267] folding (~ -x) >= (-2147483647-1) to x != -2147483648
Date: Wed, 27 Dec 2006 17:01:00 -0000 [thread overview]
Message-ID: <20061227170114.9485.qmail@sourceware.org> (raw)
In-Reply-To: <bug-30267-128@http.gcc.gnu.org/bugzilla/>
------- Comment #2 from pinskia at gcc dot gnu dot org 2006-12-27 17:01 -------
(In reply to comment #1)
> Note this is actually wrong-code.
No, it is not.
In notneg, if x is -2147483647-1, it is obviously, we have an overflow as
-(-2147483647-1) is overflowed.
In negnot, if x is 2147483647, then ~ 2147483647 == -2147483647-1, and then we
have an overflow.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30267
next prev parent reply other threads:[~2006-12-27 17:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-20 14:35 [Bug c/30267] New: missed optimization due to bad range propagation without -fwrapv bruno at clisp dot org
2006-12-27 16:48 ` [Bug middle-end/30267] folding (~ -x) >= (-2147483647-1) to x != -2147483648 rguenth at gcc dot gnu dot org
2006-12-27 17:01 ` pinskia at gcc dot gnu dot org [this message]
[not found] <bug-30267-4@http.gcc.gnu.org/bugzilla/>
2021-06-08 8:47 ` pinskia at gcc dot gnu.org
2021-06-08 11:09 ` bruno at clisp dot org
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