  As applications get developed, bugs inevitably get introduced. Often, it is
unclear why a given code change introduced a given bug. To find this causal
relation and more effectively debug, developers can leverage the existence of a
previous version of the code, without the bug. But traditional debug-ging tools
are not designed for this type of work, making this operation tedious. In this
article, we propose as exploratory work the echo-debugger, a tool to debug two
different executions in parallel, and the Convergence Divergence Mapping (CDM)
algorithm to locate all the control-flow divergences and convergences of these
executions. In this exploratory work, we present the architecture of the tool
and a scenario to solve a non trivial bug.
