Intel Advisor optimal flags and settings

Question

I'm reading this tutorial about code vectorization using Intel Advisor. In particular in this page they suggest to:

Build the target sample application in release mode ... compiler options: -O2 -g

And following:

To build your own applications to produce the most accurate and complete Vectorization Advisor analysis results, build an optimized binary in release mode using the following settings.

-g -O2 (or higher) -qopt-report=5 -vec -simd -qopenmp

Now, I have a couple of questions:

1. I thought that in release mode we didn't produce any debug information (which is produced in the "debug mode"), so no -g should be included
2. The weirdest thing is that in the Makefile given for the samples code (vec_samples in /opt/intel/advisor_*/...) uses only -g -O2 why they don't include all the other options. Why?

Answer 1

The relevant entry point to fresh Intel Advisor tutorials is Getting Started, where you can pick and choose appropriate sub-tutorials. Vectorization Advisor sub-tutorial for Linux can be found here. It precisely says that:

-qopt-report=5 : necessary for version 15.0 of the Intel compiler; unnecessary for version 16.0 and higher

With regards to -vec, -simd, -openmp, the tutorial slightly confuses flags needed for proper Advisor functioning (-g, -O2, optionally -opt-report) vs. flags needed for "proper" Compiler functioning ( -vec, -simd and -openmp). The later ones are just flags controlling compiler's vector code generation, they have nothing to do with Advisor profiling capabilities so you may or may not use them.

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To give you deeper understanding: there is an important feature in Advisor, which is called Intel Advisor Survey "Compiler Integration". This feature leverages the data relatively similar but not identical to opt-report. In order to make this feature working you need

1. Using Intel Coimpiler 14.x beta, 15.x, 16.x or 17.x
2. -g (enable debug info) and -O2 or higher (enable some optimization)
3. Optional (for Intel Compiler 15.x only) -qopt-report5

All other features in Intel Advisor work equally well regardless of Compiler version (item 1 above) or opt-report and versions (item 3 above) , but they all still require -g (part of option 2 above). -O2 is not needed for some features, but it is typically useless to deal with -O0 or -O1 compiled binaries when analyzing performance aspects.