I was trying the nettle-benchmark program and found that it hangs at startup burning 100% CPU.

Debugging shows this is when measuring benchmark overhead. With a quick printf of the "ncalls" variable in time_function(), I can see that it overflows:

time_function ncalls=100 elapsed=0.000010 time_function ncalls=1000 elapsed=0.000003 time_function ncalls=10000 elapsed=0.000002 time_function ncalls=100000 elapsed=0.000002 time_function ncalls=1000000 elapsed=0.000002 time_function ncalls=10000000 elapsed=0.000002 time_function ncalls=100000000 elapsed=0.000002 time_function ncalls=1000000000 elapsed=0.000002 time_function ncalls=1410065408 elapsed=0.000002 time_function ncalls=1215752192 elapsed=0.000002 time_function ncalls=-727379968 elapsed=0.000002 time_function ncalls=1316134912 elapsed=0.000002 time_function ncalls=276447232 elapsed=0.000002 time_function ncalls=-1530494976 elapsed=0.000002 time_function ncalls=1874919424 elapsed=0.000002 time_function ncalls=1569325056 elapsed=0.000002 time_function ncalls=-1486618624 elapsed=0.000002 time_function ncalls=-1981284352 elapsed=0.000002 time_function ncalls=1661992960 elapsed=0.000002 time_function ncalls=-559939584 elapsed=0.000002 time_function ncalls=-1304428544 elapsed=0.000002 time_function ncalls=-159383552 elapsed=0.000002 time_function ncalls=-1593835520 elapsed=0.000002 time_function ncalls=1241513984 elapsed=0.000002 time_function ncalls=-469762048 elapsed=0.000002 time_function ncalls=-402653184 elapsed=0.000002 time_function ncalls=268435456 elapsed=0.000002 time_function ncalls=-1610612736 elapsed=0.000002 time_function ncalls=1073741824 elapsed=0.000002 time_function ncalls=-2147483648 elapsed=0.000002 time_function ncalls=0 elapsed=0.000002 time_function ncalls=0 elapsed=0.000002 time_function ncalls=0 elapsed=0.000002

The elapsed time is the same regardless of ncalls, so I'm thinking that the compiler as been clever and optimized bench_nothing() into literally nothing. If I modify it to

static void bench_nothing(void *arg UNUSED) { static int i = 0; i++; return; }

then things work, but of course we're not benchmarking "nothing" anymore.

This is on Fedora 32 with gcc-10.1.1-1.fc32.x86_64

Regards, Daniel