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==Examples==
*The "COBOL Optimizer" developed by [[Capex Corporation]] in the mid 1970s for [[COBOL]]. This type of optimizer depended, in this case, upon knowledge of 'weaknesses' in the standard IBM COBOL compiler, and actually replaced (or [[patch (computing)|patch]]ed) sections of the object code with more efficient code. The replacement code might replace a linear [[lookup table|table lookup]] with a [[binary search algorithm|binary search]] for example or sometimes simply replace a relatively slow instruction with a known faster one that was otherwise functionally equivalent within its context. This technique is now known as [[strength reduction]]. For example, on the [[IBM/360]] hardware the '''CLI''' instruction was, depending on the particular model, between twice and 5 times as fast as a '''CLC''' instruction for single byte comparisons.<ref>http://www.bitsavers.org/pdf/ibm/360/A22_6825-1_360instrTiming.pdf</ref><ref>http://portal.acm.org/citation.cfm?id=358732&dl=GUIDE&dl=ACM</ref>
===Advantages===
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