Jeroen, the difference is that level 3 is using the internal implementation of sqrt in the compiler instead of calling the sqrt function. The internal path goes to R_sqrt which is defined as
# define R_sqrt(x) (ISNAN(x) ? x : sqrt(x)) so you could check if that is where the problem happens. It theory NA should yield itself, but perhaps the compiler thinks all NANs are equal and will return a constant one. If that's not it, then something else in the direct FastMath1(R_sqrt, R_SqrtSym) path... Cheers, Simon > On Sep 14, 2015, at 8:49 AM, Jeroen Ooms <jeroen.o...@stat.ucla.edu> wrote: > > When building R-devel with gcc 5.2.0 (mingw-w64 v4) on Windows, make > check fails reg-tests-1b.R at the following check: > > x <- c(1:2, NA) > sx <- sd(x) > !is.nan(sx) > > Here 'sx' should be 'NA' but it is 'NaN'. It turns out this problem > only appears when the function is byte compiled with optimization > level 3: > > mysd <- function (x, na.rm = FALSE) > sqrt(var(if (is.vector(x)) x else as.double(x), na.rm = na.rm)) > > mysd(x) > # [1] NA > compiler::cmpfun(mysd, list(optimize = 1L))(x) > # [1] NA > compiler::cmpfun(mysd, list(optimize = 2L))(x) > # [1] NA > compiler::cmpfun(mysd, list(optimize = 3L))(x) > # [1] NaN > > The problem does not appear with gcc 5.2.0 on Debian, and also not > with gcc 4.9.3 on Windows. Where do I start debugging this? The > disassembled output from the compiled functions is here: > https://gist.github.com/jeroenooms/3206945a6db6680a9c5c > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
