Infamous PR fortran/19925

[Dominique Dhumieres]

> ... saving off a pointer to the end of this list should cure the CPU time.

I am not sure that will be enough. If I read the code correctly, there are
two passes: one to build the list (for which your proposal will change the
quadratic behavior to a linear one) and one to "evaluate" it starting from
the end. For the later I think a pointer to the ancestor will also be required
("double-linked list?) to get a linear behavior.

Now constructors are intended to build vectors, using a list to descibe them
does not seem to be the right solution (it may explain the large prefactor
I have found for pr34554).

Dominique

PS I think this thread should be redirected toward pr19925.