RFC: traceback feature for gfortran

[FX Coudert <fxcoudert at gmail dot com>]

Hi gfortranners,

This proposed patch adds a traceback feature: for code compiled with 
the -ftrace function, a backtrace of function called is printed after a 
runtime failure. For now, this is only enable in conjunction of the 
-ffpe-trap function (by adding a signal handler for SIGFPE), but the 
framework can be used for any kind of error.

All kinds of comments appreciated. This is not yet a formal patch 
proposal, I'm just asking for feedback about the feature, the way it is 
implemented, the english, anything!

A testcase to play with:

$ cat trace.f
      subroutine CeciCela
      integer i
      real x

      x = 1
      do i = 1, 50
        x = exp(x)
        print *, x
      end do

      end

      subroutine truc1
        call truc2
        call truc3
      end
      subroutine truc2
        call truc3
      end
      subroutine truc3
      end
      subroutine truc4
        call truc5
        call truc5
        call truc6
      end
      subroutine truc5
      end
      subroutine truc6
        call CeciCela
      end

      program test
      call truc1
      call truc2
      call truc3
      call truc4
      end
$ gfortran trace.f -ffpe-trap=overflow -ftrace=frame && ./a.out
   2.718282
   15.15426
   3814273.
Floating point exception

Trace of last functions (innermost first):
  - cecicela (in file trace.f)
  - truc6 (in file trace.f)
  - truc4 (in file trace.f)
  - MAIN program (in file trace.f)



FX

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