https://issues.dlang.org/show_bug.cgi?id=17523
--- Comment #13 from Walter Bright <bugzi...@digitalmars.com> --- So the way forward is to follow the flow backwards to where c.Iop is being set and print that. I'd start with line 1384: pc.Iop = opcode; and insert: printf("test1: opcode = 0x%x\n", opcode); Ain't debugging fun? :-) --