Dear mentors, while updating SCTK package I enabled the execution of the test suite which was previously disabled. The tests are working fine on x86_64 architecture, but a couple of them are failing on i386. After investigation [1] I found out that tests are failing because they rely on the assumptions that, when a and b have the same double value: 1) "a < b" is false; 2) "a - b" is 0.0. Unfortunately, these assumptions do not always hold on i386 as the behavior of those operators seem to change according to compilation flags (e.g., optimization or debug flags) or the surrounding instructions (e.g., if a function is invoked nearby or not).
I think the reason for this behavior is probably related to gcc options -mfpmath [2] and -ffloat-store [3]. Using -ffloat-store option indeed seems to fix the issue. However I am wondering: 1) if enabling -ffloat-store is an acceptable solution; 2) if this is a compiler bug (I always expect approximated results with double arithmetics, but the above assumptions seem very basic to me, considering that they cover the special case where a and b are equal); 3) what is the most appropriate solution. Do you have any suggestion? I just asked the same question upstream, but I would appreciate your opinion as well. Bests, Giulio [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=981030#39 [2] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/x86-Options.html#x86-Options [3] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/Optimize-Options.html#Optimize-Options
