alt Hacker NewsGCC -O1 and clang -O1 will both optimize this function under the assumption that inputs that cause signed integer overflow are never passed:
int will_overflow(int a, int b) {
int sum = a + b;
if (b > 0 && sum < a)
return 1;
return 0;
}Replies
skydhash • today at 12:17 PM
Wouldn’t be better to check both inputs before against the max value of that type instead of actually doing the overflow?
➕ show 1 reply
Right, good example, and both GCC and Clang offer well understood parameters for deciding, per compilation unit, what behavior you want for signed overflow (-fwrapv, -fno-strict-overflow, etc), so in reality it's quite far from spooky arbitrary nasal demons.