RE: [eigen] 3.3-beta2 released!

[<Daniel.Vollmer@xxxxxx>]

Hi,

thanks for everyone's efforts. The detailed changelog and release notes are very helpful.

I've tried out our code with Eigen 3.3-beta2 (and with some fixes to unsupported/AutoDiffScalar and some massaging around clang) it now compiles. :)

Using Eigen-3.3-beta2 versus 3.2.9 results in a slow-down of about 15% with g++-6.1 and a slow-down of about 10% using clang Apple LLVM version 7.3.0 (clang-703.0.31). This was compiling with -Ofast and -DNDEBUG.

We don't do anything fancy in our CFD code, mainly small, fixed size (e.g. 5x5 / 5x1) matrix and vector products,  occasionally hard-coding specific matrix decompositions, and a fair amount of direct element accesses (either single coeff, or row/ col / segment based).
Unfortunately, I find it quite difficult to extract helpful (or actionable) profiles to see what sort changes may be causing the differences for us. Our code (like many C++ codes) is quite sensitive to inlining decisions by the compiler.


Best regards

Daniel Vollmer

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Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)
German Aerospace Center
Institute of Aerodynamics and Flow Technology | Lilienthalplatz 7 | 38108 Braunschweig | Germany

Daniel Vollmer | AS C²A²S²E
www.DLR.de