------- Comment #4 from ullner at gmail dot com 2010-03-08 17:59 ------- That still doesn't make sense. 1. Why does enabling -O3 (O1 and O2 does the same) remove this problem? 2. Why does storing the value in an intermediate variable make any change in what the result is?
Consider without O3: (long long)std::pow(2.0, 64); // Overflow. (long long)std::pow(2.0, 64.0); // OK double d1 = std::pow(2.0, 64); (long long)d1; // Overflow double d2 = std::pow(2.0, 64.0); (long long)d2; // Overflow long long l1 = d1; // l1 Overflows long long l2 = d2; // l2 Overflows Enabling -O3 causes every one of those that overflows to be OK. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43284
