Not working with -O3

[iceaway]

There seems to an issue when using gcc version 9.2.0 and higher optimization levels. I had to go down to -O0, otherwise the program segfaults. I tried debugging using gdb and simple "printf", and when using gdb it would trace the segfault to the line:

Complex v = {(float)(buf[ei * 2 + 0] - 128), (float)(buf[ei * 2 + 1] - 128)};

even though the index would not point outside the allocated space of buf. When using printf to debug, it appears to segfault in the return from the function run_for_frequencies. Neither makes much sense to me. Anyway, using -O0 solved the problem so that is a workaround.

[ThomasHabets]

The segfault is likely because run_for_frequencies is defined to return int, but there's no return.

Yes, failing to return an int is undefined behaviour, and can cause anything, including segfault. Change it to void, and it worked fine. At least for me.