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Re: [PATCH] Clarify that -fwrapv covers all signed arithmetic overflow
- From: Paolo Bonzini <bonzini at gnu dot org>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: gcc-patches at gcc dot gnu dot org, gerald at pfeifer dot com
- Date: Tue, 17 Nov 2015 18:07:05 +0100
- Subject: Re: [PATCH] Clarify that -fwrapv covers all signed arithmetic overflow
- Authentication-results: sourceware.org; auth=none
- References: <1447763566-2529-1-git-send-email-bonzini at gnu dot org> <alpine dot DEB dot 2 dot 10 dot 1511171254190 dot 4472 at digraph dot polyomino dot org dot uk> <564B27AE dot 6060506 at gnu dot org> <alpine dot DEB dot 2 dot 10 dot 1511171526510 dot 14808 at digraph dot polyomino dot org dot uk> <564B4CBB dot 5040103 at gnu dot org> <alpine dot DEB dot 2 dot 10 dot 1511171557420 dot 14808 at digraph dot polyomino dot org dot uk>
On 17/11/2015 17:02, Joseph Myers wrote:
> On Tue, 17 Nov 2015, Paolo Bonzini wrote:
>
>> * it doesn't promise that GCC will never rely on undefined behavior
>> rules for signed left shifts
>
> I think we should remove the ", but this is subject to change" in
> implement-c.texi (while replacing it with noting that ubsan will still
> diagnose such cases, and they will also be diagnosed where constant
> expressions are required).
That's great. I'll send a patch.
Paolo