Date Added: Jan 2011
Inherent within complex instruction set architectures such as x86 are inefficiencies that do not exist in a simpler ISAs. Modern x86 implementations decode instructions into one or more micro-operations in order to deal with the complexity of the ISA. Since these micro-operations are not visible to the compiler, the stream of micro-operations can contain redundancies even in statically optimized x86 code. Within a processor implementation, however, barriers at the ISA level do not apply, and these redundancies can be removed by optimizing the micro-operation stream.