list, There were discussion on this list about this bug in the debian package:
st> 0.1 Object: 1 error: The program attempted to divide a number by zero ZeroDivide(Exception)>>signal (ExcHandling.st:254) SmallInteger(Number)>>zeroDivide (SysExcept.st:1426) Fraction>>setNumerator:setDenominator: (Fraction.st:485) Fraction class>>numerator:denominator: (Fraction.st:66) Fraction>>- (Fraction.st:151) ... st> 4294967296 * 4294967296 0 Last night I tracked it down. It only happens with: * 64 bit arch * gcc 4.9.x The reason is smalltalk has to detect integer multiplication overflow reliably; and there were 3 ways in the code: 1. use __builtin_mul_overflow 2, see if the result is too big or too small 3, basically a * b / b == a ? OK : OVERFLOW gcc 5+ and clang use 1. 32 bit arch use 2. they all works. However, on gcc 4.9 and 64 bit it has to fall back to 3 which does not work. The reason is gcc is being overly smart and optimize it away. gcc does provide a switch "-fwrapv" to disable this optimization, but I am not sure what other thing it may cause and we dont want to get caught in the compiler shenanigan again in other compilers or other platform. I propose to change 3 into a more conservative and slower test such as: (MAX_ST_INT / abs(b)) < abs(a) ? OVERFLOW : OK I will follow up with a patch Derek _______________________________________________ help-smalltalk mailing list help-smalltalk@gnu.org https://lists.gnu.org/mailman/listinfo/help-smalltalk
