http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43716
--- Comment #48 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2013-01-08 19:52:39 UTC --- >From comment #40: > with -ffast-math, so for example > > if (x != 0) > tem = y / x; > else > tem = 0.; > ... do sth with tem ... > > will execute y / x unconditionally based on the fact that it cannot trap. This optimization generates an exception trapped when using -ffpe-trap=invalid along with -ffast-math. This unfortunately prevents any debugging based -ffpe-trap=invalid for miscompilations occurring with -ffast-math. One thing I hope, though I am not sure about it, is that the above block is still compiled as tem=y/x if (x==0) tem=0. My original report was for '-O3 -funsafe-math-optimizations -ffinite-math-only' without -ffpe-trap=invalid. The segmentation fault resulted from the fact that some variables were used to access a table and were out of bound when the miscompilation generated some NAN (see comment #13).
