Editing CPU cache (section)

===={{Anchor|TRACE-CACHE}}Trace cache====
{{Main article|Trace cache}}

One of the more extreme examples of cache specialization is the '''trace cache''' (also known as ''execution trace cache'') found in the [[Intel]] [[Pentium&nbsp;4]] microprocessors. A trace cache is a mechanism for increasing the instruction fetch bandwidth and decreasing power consumption (in the case of the Pentium&nbsp;4) by storing traces of [[instruction (computer science)|instruction]]s that have already been fetched and decoded.<ref>{{cite web |author=Shimpi |first=Anand Lal |date=2000-11-20 |title=The Pentium 4's Cache – Intel Pentium&nbsp;4 1.4&nbsp;GHz & 1.5&nbsp;GHz |url=http://www.anandtech.com/show/661/5 |access-date=2015-11-30 |publisher=[[AnandTech]]}}</ref>

A trace cache stores instructions either after they have been decoded, or as they are retired. Generally, instructions are added to trace caches in groups representing either individual [[basic block]]s or dynamic instruction traces. The Pentium&nbsp;4's trace cache stores [[micro-operations]] resulting from decoding x86 instructions, providing also the functionality of a micro-operation cache. Having this, the next time an instruction is needed, it does not have to be decoded into micro-ops again.<ref name="agner.org" />{{rp|63&ndash;68}}