On 2018-07-09 10:49, Corinna Vinschen wrote: > On Jul 9 15:47, Lavrentiev, Anton (NIH/NLM/NCBI) [C] wrote: >> Hello, >> >> the following sample coredumps with FPE at localhost.cc:1962 with the latest >> snapshot (6/29/2018): ... > You can simplify your testcase by not calling any time functions: > > #define _GNU_SOURCE > #include <fenv.h> > #include <stdio.h> > #include <stdlib.h> > > #define SECSPERDAY 86400 > > int main(int argc, char **argv) > { > feenableexcept(FE_ALL_EXCEPT); > long tdays = argc > 1 ? strtol (argv[1], NULL, 10) : 189; > long seconds = tdays * SECSPERDAY + 0.5; > printf ("%ld\n", seconds); > } > > This generates a SIGFPE on Linux as well. > > The line computing seconds is the same line as used by the localtime > function. Cygwin shares the entire localtime code with the various > BSDs, so I guess they would have the same problem. What is that line meant to do? Am I missing something? It should be the equivalent of (tdays*SECSPERDAY*2 + 1)/2! It converts an integer value to double, adds 1/2, and throws it away on conversion back, unless the intermediate has insufficient mantissa bits, in which case, it loses the low bits?
> Bottom line is, don't bulk enable FP exceptions, but only if you really > need it for certain parts of your code. Don't expect library functions > to be SIGFPE clean under all circumstances. Maybe selectively enable specific FPEs to check for where needed. Or be careful what you wish for, as you just might get a lot more than you bargained for ;^> -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple