Horton

Re: pg_verify_checksums and -fno-strict-aliasing

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

View thread View on postgr.es
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, Michael Paquier <michael@paquier.xyz>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, Michael Banck <michael.banck@credativ.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-08-31T11:10:08Z
Lists: pgsql-hackers 
On 31/08/2018 01:37, Tom Lane wrote:
> The fact that some of these are pretty old and we've not noticed is
> not good.  It suggests that we don't currently have any compilers in the
> buildfarm that under-align char[] arrays on the stack, which seems like
> a gotcha waiting to bite us.  I wonder if there is any way to persuade
> some compiler on a non-Intel box to do that.

-Wcast-align=strict (requires gcc-8) warns about the issue in
pg_verify_checksums.c, but also about a handful^W^W15211 other things,
so it wouldn't be immediately useful.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.