3 ms·
I'm sure I did a bunch of assembly programming on a CPU that had a flag telling you if the last calculation overflowed or not. Branch if overflow was a straigh
by kybernetikos 11y ago
I'm sure I did a bunch of assembly programming on a CPU that had a flag telling you if the last calculation overflowed or not. Branch if overflow was a straightforward opcode.
- hga 11y agoIndeed. I'm not sure how far back this goes, but definitely to the PDP-11, and looks like the IBM 360.
- mark-r 11y agoYes, but adding the branch instruction itself is the killer. If the processor had some kind of trap to set for overflow, there would be no extra instructions and no timing overhead when there wasn't an overflow.