Aliasing issue with TAILQ on ppc64 ?

[Jeff Roberson]

On Tue, 18 Sep 2012, Poul-Henning Kamp wrote:

> In message <201209181359.37965.jhb at freebsd.org>, John Baldwin writes:
>> On Tuesday, September 18, 2012 1:03:21 pm Poul-Henning Kamp wrote:
>
>> Did you have -fno-strict-aliasing enabled in CFLAGS for your PPC64 build
>> (assuming you had built with -O2 or higher)?
>
> I tried that, but it did not seem to make a difference.

If you compile at low optimization levels I assume it goes away?

Can you place asm volatile ("" ::: "memory"); between the two tailq macros 
with the same optimization level?  This should prevent gcc from caching 
anything in registers regardless of the optimization level and would tell 
us if it's doing something bad.

Thanks,
Jeff

>
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> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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