Difference between dead-code and unreachable code

how to handle the dead code and unreachable code in design what is the difference between them
1)do we need to write more number of test cases to cover the unreachable code
2) filter out unreachable code
3) delete the unreachable code

In reply to divyadm:

how to handle the dead code and unreachable code in design what is the difference between them

  • I have the impression that dead code represents a piece of logic that is not connected to anything. Typically, synthesis tools identify and remove dead code.
  • Unreachable code is code that cannot be reached because logical conditions are such that it cannot be reached. You may have experienced this with FSM states, particularly if contradictory statements prevent the entry into certain states. A simple example maybe a set of inputs that are hardwired of zero. In that case, one can consider this unreachable code as dead code.

1)do we need to write more number of test cases to cover the unreachable code

  1. filter out unreachable code
  2. delete the unreachable code

Again, tools remove such code.
Ben Cohen
http://www.systemverilog.us/ ben@systemverilog.us
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