[Rd] Possible NA Propagation Failure in RISC-V64 CPU?

[Ivan Krylov]

On Thu, 23 Feb 2023 15:39:08 -0800
Jane He <siyaoh4 using uci.edu> wrote:

> In short, according to my understanding of R's convention, any
> calculation involving NA but no NaN should result in NA (called NA
> propagation), and any calculation involving NaN but no NA should
> result in NaN. Calculations involving both NA and NaN can result in
> either value.

The ?NA help page already contains a warning that "future CPUs and/or
compilers" may prevent NA from resulting in computations with NA. A
similar problem has been encountered on Apple processors, but a
workaround was found there:
https://blog.r-project.org/2020/11/02/will-r-work-on-apple-silicon/#nanan-payload-propagation

> This failure in NA propagation may cause many R packages like mice to
> not work properly, and results in the `make check` test in the
> `stats` package to fail.

Perhaps the way forward is to update the tests.

Regarding R packages, since is.na() is already documented to return
TRUE for all NaNs, not only the NA value, it should be possible to make
them work even if they currently fail.

-- 
Best regards,
Ivan