[Halld-offline] SIMD Troubles

[Simon Taylor]

Hi.

Our suspicion is that there is an alignment problem on 32-bit systems 
with regard to the SIMD instructions;  Dave looked into this some time 
ago and it is not clear to us how to fix it.

I've checked in a change to Makefile.SIMD that changes the default from 
"SIMD on" to "SIMD off".  To get the SIMD instructions, one would
now need to do "make ENABLE_SIMD=yes".

Simon

Matthew Shepherd wrote:
> Hi all,
>
> It seems that the BMS system doesn't properly understand our SIMD capabilities on the machines here at Indiana.  If we do a default build, then we get a segmentation fault at the first DVector2 operation.  If we build with DISABLE_SIMD=1 then this segfault is avoided.
>
> This seems to point to two causes:
>
> (1) there is a bug in the SIMD implementation of DVector2
> (2) our machines are not capable of handling current SIMD code
>
> (1) seems unlikely since other people are using the code.  Assuming it is (2), how do we properly diagnose and fix it?
>
> -Matt
>
>
>
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