What is the difference between dead code and unreachable code?
What is the difference between dead code and unreachable code?
MISRA C defines unreachable code as code that cannot be executed, and it defines dead code as code that can be executed but has no effect on the functional behavior of the program.
What is Java unreachable code?
Every statement in any java program must be reachable i.e every statement must be executable at least once in any one of the possible flows. If any code can not be executable in any of the possible flows, then it is called unreachable code. Unreachable code in java is a compile time error.
What causes dead code Java?
A dead code is just a warning message native to Eclipse or another compiler. It is not displayed in the javac core java compiler. On the other hand, the unreachable code is an error reported by the javac Java compiler. It is officially included in java as an error.
Why does it say my code is Unreachable?
In computer programming, unreachable code is part of the source code of a program which can never be executed because there exists no control flow path to the code from the rest of the program.
What is redundant code called?
code that is never executed (known as unreachable code), code which is executed but has no external effect (e.g., does not change the output produced by a program; known as dead code).
How do you fix unreachable statements in Java?
If you keep any statements after the return statement those statements are unreachable statements by the controller. By using return statement we are telling control should go back to its caller explicitly .
Why break is unreachable in Java?
After break 1(a) is compiled, line 12 raises an unreachable statement error because the break statement exits the for loop and the successive statement cannot be executed.
Does Java compiler remove dead code?
javac (at least from OpenJDK) does not eliminate dead code, except for compile-time constant branches used to mimic other languages’ conditional compilation (see the example at the end of this JLS section).
How do you find the dead code?
The quickest way to find dead code is to use a good IDE.
- Delete unused code and unneeded files.
- In the case of an unnecessary class, Inline Class or Collapse Hierarchy can be applied if a subclass or superclass is used.
- To remove unneeded parameters, use Remove Parameter.
Why does Java generate unreachable code errors during multiple catch statements?
When we are keeping multiple catch blocks, the order of catch blocks must be from most specific to most general ones. i.e subclasses of Exception must come first and superclasses later. If we keep superclasses first and subclasses later, the compiler will throw an unreachable catch block error.
Does Java do dead code elimination?
Eclipse compiler for Java (ECJ) is open source incremented compiler. We reform features of ECJ, related to optimization technique called as dead code detection and elimination. ECJ identifies the dead code. We are extending this compiler to eliminate the dead code.