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Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined be
From: |
Michael Tokarev |
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 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131103 Icedove/17.0.10 |
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
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic,
Michael Tokarev <=
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Peter Maydell, 2014/04/06
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Michael Tokarev, 2014/04/06
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Peter Maydell, 2014/04/06
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Peter Maydell, 2014/04/06
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Richard Henderson, 2014/04/07
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Peter Maydell, 2014/04/07
- Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Markus Armbruster, 2014/04/07
Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/3] int128.h: Avoid undefined behaviours involving signed arithmetic, Avi Kivity, 2014/04/07