Explain briefly Dead code Elimination of the commonly used code optimization techniques

Dead code Elimination:

Code which is unreachable or which does not influence the program (for example dead stores) can be removed. In the illustration below, the value assigned to i is never utilized, and the dead store can be removed. The first assignment to global is dead, and the third assignment to global is not reachable; both can be removed.

int global; void f (){ int i;

i = 1;          /* dead store */

global = 1;     /* dead store */

global = 2;

return;

global = 3;     /* unreachable */}

Below is the code fragment after dead code elimination.

int global;

void f (){ global = 2; return;}