http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56579
Markus Trippelsdorf <markus at trippelsdorf dot de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |markus at trippelsdorf dot | |de --- Comment #2 from Markus Trippelsdorf <markus at trippelsdorf dot de> 2013-03-09 16:22:19 UTC --- (In reply to comment #1) > Something in the back of my mind has since reminded > me of -fno-aggressive-loop-optimizations, and compiling > at (e.g.) -O3 using -fno-aggressive-loop-optimizations > no longer segfaults and produces the expected output. That most likely means that the programm is invoking undefined behaviour and thus invalid. A quick check with "clang++ -fsanitize=undefined" confirms this: ... paq8kx_v7.cpp:1795:13: fatal error: signed integer overflow: 707863021 * 8 cannot be represented in type 'int'