More detail than I had intended on Layout description language

[Angela Lin]

"panama-spec-experts" <panama-spec-experts-bounces at openjdk.java.net> wrote
on 02/12/2015 11:05:51 AM:

> From: Tobi Ajila/Ottawa/IBM at IBMCA
> To: David Chase <david.r.chase at oracle.com>
> Cc: Doug Lea <dl at cs.oswego.edu>, panama-spec-experts at openjdk.java.net
> Date: 02/12/2015 11:07 AM
> Subject: Re: More detail than I had intended on Layout description
language
> Sent by: "panama-spec-experts"
<panama-spec-experts-bounces at openjdk.java.net>
>
>
> >Do GPUs enter into the float issue at all, or do they use processor
> formats?
> From my research popular GPUs such as Nvidia adhere to the IEEE754
standard
> https://developer.nvidia.com/sites/default/files/akamai/cuda/files/
> NVIDIA-CUDA-Floating-Point.pdf
>

The IEEE754 standard allows leeway for implementations to omit certain
features. For example, the extended and extendable precision formats may or
may not be implemented. I think IEEE754 also allows the results of a
sequence of operations to differ depending on how a compiler optimizes
them. So the result of a floating point computation in the VM might differ
from the result from a GPU native library. This suggests that we should
discourage performing fp operations interchangeably across Java (on host
CPU) and GPU.

OpenCL seems to have a non-IEEE754-compliant mode of operation.