http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58928
--- Comment #5 from Michael Barker <mikeb01 at gmail dot com> --- (In reply to Jakub Jelinek from comment #4) > Intel(R) Xeon(R) CPU E5620 @2.40GHz > is not IvyBridge, plus even IvyBridge doesn't support lzcnt insn, only > Haswell or some recent AMD CPUs. So, this looks like user error, you > shouldn't compile code you intend to run on non-lzcnt CPUs with -mlzcnt. Sorry, shelled into the wrong machine when running the command. Actual model number is (i7-3770). Happy with the explanation, please close. There is a further issue that the bug.c code won't compile under g++, due to a missing builtin. /.../lzcntintrin.h:38:29: error: ‘__builtin_clzs’ was not declared in this scope return __builtin_clzs (__X); However I will raise a separate bug for that.
