SSE4

SSE4 is a set of SIMD instructions for the x86 architecture, introducing a second level of SSE instructions, divided into two subsets: SSE4.1 and SSE4.2. It extends the 128-bit vector processing first introduced with SSE2 and is supported by most modern Intel and AMD processors. SSE4.1 debuted with Intel's Core microarchitecture in the late 2000s, with broad adoption across subsequent CPUs; SSE4.2 followed later, adding further instructions. The instructions operate on 128-bit XMM registers (XMM0–XMM15 in current implementations) and are designed to accelerate multimedia, text processing, cryptography, and data-parallel workloads.

SSE4.1 provides a set of integer and data-processing enhancements, including new operations for inserting and extracting scalar elements into and from vectors, blended selection between vectors, and enhanced comparisons and tests. These enable more efficient vectorized code without leaving the SSE4.1 instruction set.

SSE4.2 adds additional capabilities focused on string/character processing, bitwise operations, and data integrity checks. Notable additions include CRC32 for fast error-detection checksums, a population count instruction (POPCNT) that counts set bits, and a family of string/character comparison instructions that streamline text processing tasks.

Use and support: Software can leverage SSE4 via compiler intrinsics or auto-vectorization, with runtime checks using CPUID to select optimized code paths. Widespread support exists on modern PCs; older or embedded processors may lack all features. See also related SIMD extensions and the broader x86 architecture.