Speculative execution
（重定向自Speculative evaluation）
Speculative execution is an optimization technique where a computer system performs some task that may not be actually needed. The main idea is to do work before it is known whether that work will be needed at all, so as to prevent a delay that would have to be incurred by doing the work after it is known whether it is needed. If it turns out the work was not needed after all, any changes made by the work are reverted and the results are ignored.