contiguous arrays are discussed in pp.139-145 of “Modern Fortran Explained: Incorporating Fortran 2018”.
In general, operating on contiguous arrays is faster than non-contiguous arrays.
Contiguous variables happen by default, so unless using pointers or array striding, the variable is likely to be contiguous for simple Fortran code.
Check contiguous status of a variable with
is_contiguous intrinsic function.
A non-contiguous array actual argument into a
contiguous subroutine dummy argument is made contiguous by copy-in, copy-out.
This copy-in copy-out as needed is part of the
GCC ≥ 9,
IBM Open XL Fortran,
etc. work to Fortran 2008+ standard for
contiguous dummy argument copy-in, copy-out for non-contiguous actual argument.
References: Fortran 2008 Contiguity