I do not know how things are rolling inside SDBG, how things will be slowed down or how difficult is to add new features, but even the speed of a turtle sometimes would fit. Our programs not always are for speed. This is why we are fans of this compiler by the way, not Intel or gFortran 😃 which sometimes show speedups up to 30x on couple tasks in Polyhedron. if speed is needed we take critical section compiled in fast compilers in the forms of DLLs and add/link it to FTN95.
Often speed even not an issue at all. The numerous IF() GOTO NNN logic, complex jumps READ(.... err=NNN, end=MMM) often require which specifically line of source code caused this jump to label NNN or MMM.
Reading initial settings files always kills me. With time and new code versions their structure becomes hell complex and always gets errors reading versions 3 or 10 years old. You will not find errors there quickly, it is bloody mess. Seeing which lines were read and which were skipped would allow to debug such places in minutes. Instead i do not touch such places for years even knowing error is there if error is not critical
And may be i was not clear. No stop on each line is needed, just keeping in the added memory array of size (2,100) the line number where code was executed and name of function/subroutine. Yes, adding the functionality in the debugger to jump to previous line as a 'curtesy' would make this process nicer. But even listing this bare array (2,100) would help