3 ms·

Note that even an in-order processor that is pipelined and has a branch predictor to not stall the pipeline on every conditional branch does "speculative execut

• brucehoult 8y ago
  Sort of. Later instructions are fetched and decoded speculatively, but because the processor is in-order they don't get to the execute stage (let alone write-back) before the misprediction is discovered. All that has to be flushed is the fetch and decode, which doesn't change any visible state anyway. (hmm .. except icache contents .. the mispredicted branch might evict something else from the icache .. but the load from L2 or main memory will probably take longer than the pipeline length, so could be shot down before updating the icache)