Accomplish common subexpression elimination in Eclipse Compiler

Eclipse is an integrated development environment (IDE). Eclipse has imposed its own compiler called as Eclipse Compiler for Java (ECJ). Eclipse compiler is a compiler for Java programming language. Java class files are the most common form of output of an Eclipse compiler. Common subexpression elimination (CSE) is an optimization technique of compiler. It searches for instances of identical expressions, and analyses whether it is previously executed and replacing them with a single variable holding the computed value. CSE converts binary operation into assignment operation when same binary expression is evaluated. In this paper we design an algorithm for CSE to implant into ecj. After that we analyse experimental results which gives idea how the CPU time is reduced to evaluate the complex expression. Reason behind reducing CPU and compilation timing is that no. of binary operation is reduced and replace by an assignment operation. Hence we utilize the CPU time because assignment operation has lowest precedence than other operation and efficiency of compiler may be improved.