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Date: Sat, 8 Sep 2018 13:14:24 +0200
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Subject: Re: [PHP-DEV] GCC -foptimize-strlen and bug #76510
From: cmbecker69@gmx.de ("Christoph M. Becker")

On 08.09.2018 at 09:59, Sebastian Bergmann wrote:

> On 08/04/2018 11:51 PM, Nikita Popov wrote:
>> More likely than not this is a bug on our side triggered by this
>> optimization, not a bug in GCC. A run through valgrind might reveal
>> something.
> 
> Valgrind information has been added to
> https://bugs.php.net/bug.php?id=76510.
> 
> Can an optimization such as "optimize-strlen" be disabled on a per-file
> (or better, on a per-function) basis as a (hopefully) short-term workaround?

The actual bug (not was is reported by valgrind) is caused by a compiler
optimization bug in GCC[1]; even some distros are already deploying
fixes.  Since this bug is likely to affect other parts of php-src and
even extensions, I don't think it makes sense to disable optimize-strlen
for individual files only, but I rather suggest to check whether
optimize-strlen is broken, and if so to add -fno-optimize-strlen to the
CFLAGS (etc.)

Regardless how we work around the optimization bug, we should do it
ASAP.  php-7.3.0RC1 is scheduled for tagging on Tuesday.  A patch/PR
would be appreciated.

[1]
<https://github.com/php/php-src/commit/513b0093c2b480bb752fb354012f42c446769486#commitcomment-30359209>ff

-- 
Christoph M. Becker