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Date:      Sat, 04 Feb 2006 13:19:37 +0100
From:      des@des.no (=?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?=)
To:        Warner Losh <imp@bsdimp.com>
Cc:        src-committers@freebsd.org, harti@freebsd.org, kris@obsecurity.org, stable@freebsd.org, sparc64@freebsd.org
Subject:   Re: [releng_6 tinderbox] failure on sparc64/sparc64
Message-ID:  <86bqxntixy.fsf@xps.des.no>
In-Reply-To: <20060203.105305.71186162.imp@bsdimp.com> (Warner Losh's message of "Fri, 03 Feb 2006 10:53:05 -0700 (MST)")
References:  <8664nwrbp8.fsf@xps.des.no> <20060203102659.GA66445@xor.obsecurity.org> <861wykr9vx.fsf@xps.des.no> <20060203.105305.71186162.imp@bsdimp.com>

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Warner Losh <imp@bsdimp.com> writes:
> Can we not have special flags for tinderbox builds?  It make
> pre-commit testing a big pita.  How about just -O on both head and
> in RELENG_6?

As I have repeatedly pointed out in the past, -O2 catches more bugs
because it enables optimizations which require more extensive coverage
analysis.

> The kernel make files have special magic to disable the parts of -O2
> that are known to be bad because tinderbox uses -O2, despite efforts
> in the past to stop the practice.

The kernel has special magic to disable strict aliasing checks because
certain people regularly commit kernel code which violates C aliasing
rules and refuse to fix it.  The userland code does not need these
hacks because I spent a lot of time and effort fixing aliasing bugs in
e.g. libalias.

Aliasing violations are not trivial matters; they prevent the compiler
from optimizing code which (for instance) accesses structure members
through pointers to the structure.  There is a lot of this in the
kernel.

DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no



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