Computational Physics Lectures: How to optimize codes, from vectorization to parallelization

Compiling with and without vectorization using clang

We can compile and link without vectorization with clang compiler

clang++ -o -fno-vectorize novec.x vecexample.cpp

and with vectorization

clang++ -O3 -Rpass=loop-vectorize -o  vec.x vecexample.cpp

We can also add vectorization analysis, see for example

clang++ -O3 -Rpass-analysis=loop-vectorize -o  vec.x vecexample.cpp

or figure out if vectorization was missed

clang++ -O3 -Rpass-missed=loop-vectorize -o  vec.x vecexample.cpp