From: Michael Tokarev <mjt@tls.msk.ru>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-trivial@nongnu.org, qemu-devel@nongnu.org, patches@linaro.org
Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic
Date: Sun, 06 Apr 2014 11:09:23 +0400 [thread overview]
Message-ID: <5340FDA3.1080902@msgid.tls.msk.ru> (raw)
In-Reply-To: <1396019577-2013-3-git-send-email-peter.maydell@linaro.org>
28.03.2014 19:12, Peter Maydell wrote:
> Add casts when we're performing arithmetic on the .hi parts of an
> Int128, to avoid undefined behaviour.
[]
> static inline Int128 int128_sub(Int128 a, Int128 b)
> {
> - return (Int128){ a.lo - b.lo, a.hi - b.hi - (a.lo < b.lo) };
> + return (Int128){ a.lo - b.lo, (uint64_t)a.hi - b.hi - (a.lo < b.lo) };
What was wrong with this one? I don't think casting to unsigned here is
a good idea.
Thanks,
/mjt
next prev parent reply other threads:[~2014-04-06 7:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-28 15:12 [Qemu-devel] [PATCH 0/3] More fixes for undefined behaviour Peter Maydell
2014-03-28 15:12 ` [Qemu-devel] [PATCH 1/3] hw/ide/ahci.c: Avoid shift left into sign bit Peter Maydell
2014-04-06 7:10 ` [Qemu-devel] [Qemu-trivial] " Michael Tokarev
2014-03-28 15:12 ` [Qemu-devel] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic Peter Maydell
2014-04-06 7:09 ` Michael Tokarev [this message]
2014-04-06 10:18 ` [Qemu-devel] [Qemu-trivial] " Peter Maydell
2014-04-06 14:13 ` Michael Tokarev
2014-04-06 14:58 ` Peter Maydell
2014-04-06 15:27 ` Peter Maydell
2014-04-07 14:25 ` Richard Henderson
2014-04-07 14:47 ` Peter Maydell
2014-04-07 15:49 ` Markus Armbruster
2014-04-07 14:56 ` Avi Kivity
2014-04-07 15:17 ` Peter Maydell
2014-04-07 15:22 ` Avi Kivity
2014-03-28 15:12 ` [Qemu-devel] [PATCH 3/3] xbzrle.c: Avoid undefined behaviour with " Peter Maydell
2014-04-06 14:15 ` [Qemu-devel] [Qemu-trivial] " Michael Tokarev
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