[Rd] Two bugs showing up mostly on SPARC systems

Duncan Murdoch murdoch.duncan at gmail.com
Wed Jul 15 01:52:56 CEST 2015

On 14/07/2015 6:08 PM, Radford Neal wrote:
> In testing pqR on Solaris SPARC systems, I have found two bugs that
> are also present in recent R Core versions.  You can see the bugs and
> fixes at the following URLs:
>   https://github.com/radfordneal/pqR/commit/739a4960a4d8f3a3b20cfc311518369576689f37

Thanks for the report.  Just one followup on this one:

There are two sections of code that are really similar.  Your patch
applies to the code in port_nlsb(), but there's a very similar test in
port_nlminb(), which is called from nlminb() in R.  Do you think it
would be a good idea to apply the same patch there as well?  It doesn't
look like it would hurt, but I don't know this code at all, so it might
be unnecessary.

Duncan Murdoch

>   https://github.com/radfordneal/pqR/commit/339b7286c7b43dcc6b00e51515772f1d7dce7858
> The first bug, in nls, is most likely to occur on a 64-bit big-endian
> system, but will occur with low probability on most platforms.  
> The second bug, in readBin, may occur on systems in which unaligned
> access to data more than one byte in size is an error, depending on
> details of the compiler.  It showed up with gcc 4.9.2 on a SPARC
> system. The fix slightly changes the error behaviuor, signaling an
> error on inappropriate reads before reading any data, rather than
> after reading one (but not all) items as before.
>    Radford Neal
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