User and Reference Guide for the Intel® Fortran Compiler 14.0
The automatic vectorizer (also called the auto-vectorizer) is a component of the Intel® compiler that automatically uses SIMD instructions in the Intel® Streaming SIMD Extensions (Intel® SSE, Intel® SSE2, Intel® SSE3 and Intel® SSE4), Supplemental Streaming SIMD Extensions (SSSE3) instruction sets, and the Intel® Advanced Vector Extensions (Intel® AVX, Intel® AVX2) instruction sets. The vectorizer detects operations in the program that can be done in parallel and converts the sequential operations to parallel; for example, the vectorizer converts the sequential SIMD instruction that processes 2, 4, 8 or up to 16 elements into a parallel operation, depending on the data type.
The compiler supports a variety of auto-vectorizing hints that can help the compiler to generate effective vector instructions. Automatic vectorization is supported on IA-32 and Intel® 64 architectures.
See The Software Vectorization Handbook. Applying Multimedia Extensions for Maximum Performance, A.J.C. Bik. Intel Press, June, 2004, for a detailed discussion of how to vectorize code using the Intel® Compiler. Additionally, see the Related Publications topic in this document for other resources.
Using this option enables vectorization at default optimization levels for both Intel® microprocessors and non-Intel microprocessors. Vectorization may call library routines that can result in additional performance gain on Intel® microprocessors than on non-Intel microprocessors. The vectorization can also be affected by certain options, such as /arch (Windows*), -m (Linux* and OS X*), or [Q]x.