Execute and Writeback Decoupling Allows Program Restart
The queue for results is necessary to resolve issues such as branch mispredictions and exceptions/traps. The results queue allows programs to be restarted after an exception, which requires the instructions to be completed in program order. The queue allows results to be discarded due to mispredictions on older branch instructions and exceptions taken on older instructions.
The ability to issue instructions past branches which have yet to resolve is known as speculative execution.
Read more about this topic: Out-of-order Execution
Famous quotes containing the words execute and/or program:
“Law without education is a dead letter. With education the needed law follows without effort and, of course, with power to execute itself; indeed, it seems to execute itself.”
—Rutherford Birchard Hayes (1822–1893)
“In 1862 the congregation of the church forwarded the church bell to General Beauregard to be melted into cannon, “hoping that its gentle tones, that have so often called us to the House of God, may be transmuted into war’s resounding rhyme to repel the ruthless invader from the beautiful land God, in his goodness, has given us.””
—Federal Writers’ Project Of The Wor, U.S. public relief program (1935-1943)