Intel® 64 and IA-32 Architectures Optimization Reference Manual

INTEL® 64 AND IA-32 PROCESSOR ARCHITECTURES• Instructions that reference 32-bit general purpose registers can access 16general purpose registers in 64-bit mode.64-bit MMX RegistersMM7MM6MM5MM4MM3MM2MM1MM0128-bit XMM RegistersXMM7XMM6XMM5XMM4XMM3XMM2XMM1XMM0OM15149Figure 2-10. SIMD Instruction Register UsageSIMD improves the performance of 3D graphics, speech recognition, imageprocessing, scientific applications and applications that have the following characteristics:• inherently parallel• recurring memory access patterns• localized recurring operations performed on the data• data-independent control flowSIMD floating-point instructions fully support the IEEE Standard 754 for BinaryFloating-Point Arithmetic. They are accessible from all IA-32 execution modes:protected mode, real address mode, and Virtual 8086 mode.SSE, SSE2, and MMX technologies are architectural extensions. Existing software willcontinue to run correctly, without modification on Intel microprocessors that incorporatethese technologies. Existing software will also run correctly in the presence ofapplications that incorporate SIMD technologies.SSE and SSE2 instructions also introduced cacheability and memory orderinginstructions that can improve cache usage and application performance.2-47