I've never used a mainframe, but I did manage to introduce a small performance regression in gcc that someone complained about (I did fix it, yes). ;-) Turned

I've never used a mainframe, but I did manage to introduce a small performance regression in gcc that someone complained about (I did fix it, yes). ;-) Turned out that s390 couldn't fuse cmp+jmp when the operand was a 8-bit value (_Bool). (That was a while ago, maybe current generation mainframe HW can do it?)