An example is common subexpression elimination which removes duplicate expressions.

PRE is a form of common subexpression elimination.

Available expression analysis is used to do global common subexpression elimination (CSE).

GVN is able to identify some redundancy that common subexpression elimination cannot, and vice versa.

It sometimes helps eliminate redundant code that common subexpression elimination (CSE) does not.

Sophisticated compilers calculate such things exactly once, eliminating the following redundant calculations, using common subexpression elimination and loop-invariant code motion.

Traditional optimizations such as common subexpression elimination and loop invariant hoisting often focus on eliminating redundant computation.

Code may become unreachable as a consequence of the internal transformations performed by an optimizing compiler (e.g., common subexpression elimination).

An interesting property of PRE is that it performs (a form of) common subexpression elimination and loop-invariant code motion at the same time.

Knowing the use-def and def-use chains for a program or subprogram is a prerequisite for many compiler optimizations, including constant propagation and common subexpression elimination.

This can help in proving correctness, simplifying an algorithm, assisting in modifying code without breaking it, or optimizing code by means of memoization, common subexpression elimination or parallelization.

The exact set of GCC optimizations varies from release to release as it develops, but includes the standard algorithms, such as loop optimization, jump threading, common subexpression elimination, instruction scheduling, and so forth.

In computer science, common subexpression elimination (CSE) is a compiler optimization that searches for instances of identical expressions (i.e., they all evaluate to the same value), and analyses whether it is worthwhile replacing them with a single variable holding the computed value.

In compilers, straight line code (that is, sequences of statements without loops or conditional branches) may be represented by a DAG describing the inputs and outputs of each of the arithmetic operations performed within the code; this representation allows the compiler to perform common subexpression elimination efficiently.