Simulation and runtime debugging options
Besides the options described in :ref:`GHDL:options`, GHDL passes any debugging options (those that begin with
-g) and optimizations options (those that begin with
-f) to GCC. Refer to the GCC manual for
details. Moreover, some debugging options are also available, but not described here. The :option:`--help` option lists
all options available, including the debugging ones.
.. option:: --trace-signals Display signals after each cycle.
.. option:: --trace-processes Display process name before each cycle.
.. option:: --stats Display run-time statistics.
.. option:: --disp-order Display signals order.
.. option:: --disp-sources Display sources while displaying signals.
.. option:: --disp-sig-types Display signal types.
.. option:: --disp-signals-map Display map bw declared signals and internal signals.
.. option:: --disp-signals-table Display internal signals.
.. option:: --checks Do internal checks after each process run.
.. option:: --activity=<LEVEL> Watch activity of LEVEL signals: LEVEL is ``all``, ``min`` (default) or ``none`` (unsafe).
.. option:: --dump-rti Dump Run Time Information (RTI).
.. option:: --bootstrap Allow ``--work=std``
GNU Debugger (GDB)
.. index:: `__ghdl_fatal`
Debugging VHDL programs using GDB is possible only with GCC/LLVM.
GDB is a general purpose debugger for programs compiled by GCC. Currently, there is no VHDL support for GDB. It may be difficult to inspect variables or signals in GDB. However, it is still able to display the stack frame in case of error or to set a breakpoint at a specified line.
GDB can be useful to catch a runtime error, such as indexing an array beyond its bounds. All error check subprograms call the
__ghdl_fatal procedure. Therefore, to a catch runtime error, set a breakpoint like this:
(gdb) break __ghdl_fatal
When the breakpoint is hit, use the
bt command to display the stack frames.