The VC++ 2012 auto-vectorizer tries to make loops in your code run faster by automatically vectorizing your code using the SSE instructions available in all current mainline Intel and AMD chips. In Visual C++ 2012, auto-vectorization is on by default and requires only that you write your code—that is, there are no compiler switches, #pragmas, or hints. It just works. Of course, it's one thing to say that, but how does it work, exactly? When does it vectorize and when doesn't it? Why?



Auto-vectorization is a powerful compiler feature. In VS 12 it represents outstanding engineering by a few folks on the Microsoft Visual C++ compiler team. The engineering leader of this team is Jim Radigan. Fortunately for us, Jim has agreed to do a series of C9 lectures digging into the nuts and bolts of automatic vectorization in general and specifically as it relates to the latest version of VC++. Thank you, Jim!

In the first part of this n-part series, Jim introduces the series, describes improvements to the VC++ 2012 compilers, shares, introduces auto-vectorization, demos a few apps that benefit from compiler-optimized performance via auto-vectorization, and begins to describe how/when user code is vectorized (typical and atypical patterns alike - more to come as the lectures progress, of course). Over the course of this series, Jim will present both the practical and theoretical foundations of auto-vectorization.

(You can learn more about auto-vectorization in VC++ by reading the blog posts by Jim Hogg, another member of the VC++ compiler team working on this technology.)



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