Re: [Qemu-devel] [PULL 16/20] target/arm: Use vector infrastructure for aa64 compares

[Richard Henderson]

On 04/05/2018 10:07 AM, Richard Henderson wrote:
> On 04/05/2018 02:49 AM, Emilio G. Cota wrote:
>> 1. grab this binary:
>>   http://cs.columbia.edu/~cota/qemu/nbench-aarch64
>> 2. run it on a PowerPC host with:
>>   $ aarch64-linux-user/qemu-aarch64 nbench-aarch64 -V
>>
>> Note: the "-V" (or "-v") flag is important! Without it, there's no segfault.
> 
> How quickly?  I did not see one up until it exited for lack of NNET.DAT.
> 
> I will note that I am using gcc 7.2 on gcc112 (/opt/cfarm/gcc-latest/bin/gcc).
> 
> Are you using gcc 4.8.5, and is commit 74912f6dad in your tree?
> That commit might have made a difference...

Bah.  I confirm that it doesn't, and that the test still fails.

Since qemu does work on the same host when built with gcc 7.2, I can only blame
this failure on a compiler bug wrt gcc 4.8 on ppc64.

I have not tracked down exactly what's going wrong, and probably won't unless
someone feels that it's worthwhile.  This only begs the question of whether we
should blacklist this compiler entirely.  Certainly it's old enough that it's
probably not worth fixing.


r~