Editing Instruction scheduling (section)

{{Short description|Compiler optimization technique}}
{{Refimprove|date=April 2018}}
In [[computer science]], '''instruction scheduling''' is a [[compiler optimization]] used to improve [[instruction-level parallelism]], which improves performance on machines with [[instruction pipeline]]s. Put more simply, it tries to do the following without changing the meaning of the code:

* Avoid [[pipeline stall]]s by rearranging the order of instructions.<ref name="ColdScheduling_1994"/>
* Avoid illegal or semantically ambiguous operations (typically involving subtle instruction pipeline timing issues or non-interlocked resources).
<!-- * order the instructions to avoid duplicated memory access 
This doesn't belong in instruction scheduling
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The pipeline stalls can be caused by structural hazards (processor resource limit), data hazards (output of one instruction needed by another instruction) and control hazards (branching).