I have to complete a project for university where I need to be able to optimise using compiler optimisation levels. I am using OpenMP and as a result I have got the gcc-11 compiler from brew. I have watched this video

How do I do this?

Any advice would be appreciated

CodePudding user response：

Optimization levels are specified with -O1 etc, using capital letter O, not lower-case letter o.

Lower-case -o1 specifies that the output file should be 1, and then out/jacobi2d1 is an input file to be linked, but it is an existing executable and you can't link one executable into another — hence the error from the linker.