Horton

Re: pg_verify_checksums and -fno-strict-aliasing

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, Michael Banck <michael.banck@credativ.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-08-30T20:11:45Z
Lists: pgsql-hackers 
On 2018-08-30 10:39:26 -0400, Tom Lane wrote:
> 	char		buf[BLCKSZ];
> 	PageHeader	header = (PageHeader) buf;

> (The right fix, of course, is to malloc the work buffer rather than
> put it on the stack.)

Or alternatively, for places where such allocations could be a problem
for performance, using a union can be used to force the required
alignment.  I'm fairly certain that just allocating is more than OK
here, to be clear.

Greetings,

Andres Freund

Commits

  1. Avoid using potentially-under-aligned page buffers.

  2. Code review for pg_verify_checksums.c.

  3. Make checksum_impl.h safe to compile with -fstrict-aliasing.