https://issues.dlang.org/show_bug.cgi?id=17940
--- Comment #2 from FeepingCreature <default_357-l...@yahoo.de> --- Hah! It tries to reload the cse into ESI, but since that's a 1-byte operation (since bool), it actually becomes a move to DH. ESI is not even reachable with 1-byte ops, because those register values were used to address high regs. So for reg8 opcodes like 0x8A, code->setReg should assert on reg & 4. How to actually fix this though, no idea. --