Intel® 64 and IA-32 Architectures Optimization Reference Manual

CODING FOR SIMD ARCHITECTURESThis is because the instructions consist of two micro-ops instead of three. Relevantinstructions are: unpcklps, unpckhps, packsswb, packuswb, packssdw, pshufd,shuffps and shuffpd.Recommendation: When targeting code generation for Intel Core Solo and IntelCore Duo processors, favor instructions consisting of two μops over those with morethan two μops.Intel Core microarchitecture generally executes SIMD instructions more efficientlythan previous microarchitectures in terms of latency and throughput, many of therestrictions specific to Intel Core Duo, Intel Core Solo processors do not apply. Thesame is true of Intel Core microarchitecture relative to Intel NetBurst microarchitectures.4.7 TUNING THE FINAL APPLICATIONThe best way to tune your application once it is functioning correctly is to use aprofiler that measures the application while it is running on a system. VTune analyzercan help you determine where to make changes in your application to improveperformance. Using the VTune analyzer can help you with various phases required foroptimized performance. See Appendix A.2, “Intel® VTune Performance Analyzer,”for details. After every effort to optimize, you should check the performance gains tosee where you are making your major optimization gains.4-27