Horton

Re: strict aliasing

Florian Weimer <fweimer@bfk.de>

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From: Florian Weimer <fweimer@bfk.de>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>, "Kevin Grittner" <Kevin.Grittner@wicourts.gov>, "Robert Haas" <robertmhaas@gmail.com>, "Thomas Munro" <munro@ip9.org>, "Florian Pflug" <fgp@phlo.org>
Date: 2011-11-15T10:45:22Z
Lists: pgsql-hackers 
* Andres Freund:

> I don't gcc will ever be able to call all possible misusages. E.g. The
> List api is a case where its basically impossible to catch everything
> (as gcc won't be able to figure out what the ListCell.data.ptr_value
> pointed to originally in the general case).

Correct, if code is not strict-aliasing-safe and you compile with
-f-strict-aliasing, GCC may silently produce wrong code.  (Same with
-fwrapv, by the way.)

-- 
Florian Weimer                <fweimer@bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
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