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| [21 earlier articles] |
| Re: Optimization techniques alexfrunews@gmail.com (2019-04-26) |
| Re: Optimization techniques derek@_NOSPAM_knosof.co.uk (Derek M. Jones) (2019-04-26) |
| Re: Optimization techniques martin@gkc.org.uk (Martin Ward) (2019-04-26) |
| Re: Optimization techniques martin@gkc.org.uk (Martin Ward) (2019-04-26) |
| Re: Optimization techniques 847-115-0292@kylheku.com (Kaz Kylheku) (2019-04-26) |
| Re: Optimization techniques 0xe2.0x9a.0x9b@gmail.com (2019-04-27) |
| Re: Optimization techniques haberg-news@telia.com (Hans Aberg) (2019-04-27) |
| Re: Optimization techniques david.brown@hesbynett.no (David Brown) (2019-04-28) |
| Re: Optimization techniques david.brown@hesbynett.no (David Brown) (2019-04-28) |
| Re: Optimization techniques, C++ numeric representations david.brown@hesbynett.no (David Brown) (2019-04-29) |
| Re: Optimization techniques, C++ numeric representations haberg-news@telia.com (Hans Aberg) (2019-04-30) |
| Re: Optimization techniques genew@telus.net (Gene Wirchenko) (2019-04-30) |
| Re: Optimization techniques genew@telus.net (Gene Wirchenko) (2019-04-30) |
| [9 later articles] |
| From: | Hans Aberg <haberg-news@telia.com> |
| Newsgroups: | comp.compilers |
| Date: | Sat, 27 Apr 2019 23:01:10 +0200 |
| Organization: | A noiseless patient Spider |
| References: | <72d208c9-169f-155c-5e73-9ca74f78e390@gkc.org.uk> 19-04-020 |
| Injection-Info: | gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="6232"; mail-complaints-to="abuse@iecc.com" |
| Keywords: | C, C++, arithmetic, comment |
| Posted-Date: | 27 Apr 2019 17:13:19 EDT |
| Content-Language: | en-US |
On 2019-04-25 17:46, Martin Ward wrote:
> If signed overflow was given a defined
> behaviour (such as the two's complement result), then compilers for
> CPUs which do not implement two's complement operations would have to
> generate less efficient code (but does anyone still make such a CPU?).
All C++ compilers use two's complement, and as of C++20, that is
required, cf. [1], "Range of values". It is required for int32_t etc in
C++11 [2] and C99 [3].
1. https://en.cppreference.com/w/cpp/language/types
2. https://en.cppreference.com/w/cpp/types/integer
3. https://en.cppreference.com/w/c/types/integer
[I realize that if you look very hard, you can still find a few legacy
machines that are not pure two's complement and do not have 8-bit byte
addressing. But these days, so what. -John]
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