GNU Fortran has various special options that are used for debugging either your program or the GNU Fortran compiler.
Output the internal parse tree after translating the source program
into internal representation. Only really useful for debugging the
GNU Fortran compiler itself. This option is deprecated; use
SQRT(-1.0)), `zero' (division by zero), `overflow' (overflow in a floating point operation), `underflow' (underflow in a floating point operation), `inexact' (loss of precision during operation), and `denormal' (operation performed on a denormal value). The first five exceptions correspond to the five IEEE 754 exceptions, whereas the last one (`denormal') is not part of the IEEE 754 standard but is available on some common architectures such as x86.
The first three exceptions (`invalid', `zero', and `overflow') often indicate serious errors, and unless the program has provisions for dealing with these exceptions, enabling traps for these three exceptions is probably a good idea.
Many, if not most, floating point operations incur loss of precision
due to rounding, and hence the
ffpe-trap=inexact is likely to
be uninteresting in practice.
By default no exception traps are enabled.
-fno-backtracedisables the backtrace generation. This option only has influence for compilation of the Fortran main program.
See Options for Debugging Your Program or GCC, for more information on debugging options.