On Mon, Sep 29, 2014 at 12:09 AM, FX wrote: > Filed as PR63401: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63401 > > >> This is easy to see with a simple C test case: >> >> //__attribute__ ((optimize("strength-reduce"))) >> int foo (float x) { return __builtin_isnan(x); } >> >> Compiled with -O3 -ffast-math, the isnan is simplified out (fast math means >> no NaNs). If you uncomment the attribute (chosen because it’s actually >> useless), and compile again with -O3 -ffast-math: the isnan test is not >> simplified any more. This is because the codepath through >> default_options_optimization() has overwritten the value of the flags >> handled in set_fast_math_flags(): flag_finite_math_only, flag_signed_zeros, >> flag_trapping_math and flag_unsafe_math_optimizations. >> >> I’m CC’ing the maintainers who added the optimize attribute in the first >> place, as they might have an idea how to fix this. This is way beyond my >> league!
Perhaps Joseph can help, in his position as maintainer of the option handling subsystem. Ciao! Steven
