Eh, new instructions are added all the time. Just look at BMI - I'd be willing to bet the static power cost of adding that dwarfs what trapping arithmetic would

Eh, new instructions are added all the time. Just look at BMI - I'd be willing to bet the static power cost of adding that dwarfs what trapping arithmetic would cost. And most of those instructions are more esoteric and/or give less benefit over existing instructions than trapping arithmetic would. Also the current branches for overflow checks might be well-predicted, but only if it uses branch prediction resources that could go to other branches. Not to mention the extra codesize and issue resources taken.