Streaming SIMD Extensions - Later Versions

Later Versions

• SSE2, introduced with the Pentium 4, is a major enhancement to SSE. SSE2 adds new math instructions for double-precision (64-bit) floating point and also extends MMX integer instructions to operate on 128-bit XMM registers. Until SSE2, SSE integer instructions introduced with later SSE extensions could still operate on 64-bit MMX registers because the new XMM registers require operating system support. SSE2 enables the programmer to perform SIMD math on any data type (from 8-bit integer to 64-bit float) entirely with the XMM vector-register file, without the need to use the legacy MMX or FPU registers. Many programmers consider SSE2 to be "everything SSE should have been", as SSE2 offers an orthogonal set of instructions for dealing with common data types.
• SSE3, also called Prescott New Instructions (PNI), is an incremental upgrade to SSE2, adding a handful of DSP-oriented mathematics instructions and some process (thread) management instructions.
• SSSE3 is an incremental upgrade to SSE3, adding 16 new instructions which include permuting the bytes in a word, multiplying 16-bit fixed-point numbers with correct rounding, and within-word accumulate instructions. SSSE3 is often mistaken for SSE4 as this term was used during the development of the Core microarchitecture.
• SSE4 is another major enhancement, adding a dot product instruction, additional integer instructions, a popcnt instruction, and more.
• XOP, FMA4 and CVT16 are new iterations announced by AMD in August 2007 and revised in May 2009.
• AVX (Advanced Vector Extensions) is an advanced version of SSE announced by Intel featuring a widened data path from 128 bits to 256 bits and 3-operand instructions (up from 2). Intel released processors in early 2011 with AVX support. AVX requires support from the operating system. AVX cannot be made use of on older operating systems like Windows XP or Windows Vista, even if the CPU supports AVX.