Re: Optimization techniques

"Derek M. Jones" <derek@_NOSPAM_knosof.co.uk>
Fri, 26 Apr 2019 13:39:58 +0100

          From comp.compilers

Related articles
[16 earlier articles]
Re: Optimization techniques martin@gkc.org.uk (Martin Ward) (2019-04-25)
Re: Optimization techniques david.brown@hesbynett.no (David Brown) (2019-04-25)
Re: Optimization techniques 847-115-0292@kylheku.com (Kaz Kylheku) (2019-04-25)
Re: Optimization techniques 847-115-0292@kylheku.com (Kaz Kylheku) (2019-04-26)
Re: Optimization techniques 847-115-0292@kylheku.com (Kaz Kylheku) (2019-04-26)
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)
[11 later articles]
| List of all articles for this month |

From: "Derek M. Jones" <derek@_NOSPAM_knosof.co.uk>
Newsgroups: comp.compilers
Date: Fri, 26 Apr 2019 13:39:58 +0100
Organization: virginmedia.com
References: 19-04-004 19-04-012
Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="53580"; mail-complaints-to="abuse@iecc.com"
Keywords: optimize, design, comment
Posted-Date: 26 Apr 2019 15:12:47 EDT
Content-Language: en-US

All,


On 19/04/2019 23:27, Hans-Peter Diettrich wrote:
> I'm always a bit sceptic when C/C++ and "safe" occur in the same
> sentence. AFAIR a C compiler is allowed to ignore parentheses when
> reordering expressions, what can lead to numeric instabilities.


Not true:
"In the abstract machine, all expressions are evaluated as specified by
the semantics. "


https://c0x.coding-guidelines.com/5.1.2.3.html


--
Derek M. Jones
blog:shape-of-code.coding-guidelines.com
[Keeping in mind the "as if" rule which lets the compiler do whatever
it wants so long as the result is the same. -John]


Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.