Intel’s “Intel® 64 and IA-32 Architectures Software Developer’s Manual” page 654 (3-224 Vol. 2A) says that divq produces “#DE;” when high numerator is not less than denominator. Mach kernel reports “Floating point exception: 8” or at least the shell command reports that. The operation is ‘divq’ with RDX:RAX = 101000…:000000… and divisor is 10000… . The bug could be in Intel documentation, in the chip, in the kernel or in the shell. (Or perhaps in runtime libs.)
gcc bug.c q.s -Wmost
 Floating point exception: 8