code optimization

Peephole optimization

An optimization that works by eliminating redundant instructions from a small area of code.

Peephole optimization Local optimizations Loop optimization

Classification of Optimization techniques

reaching definitions, use-def chains and def-use chains

Copy propagation often makes use ___, ____ and ___ of when computing which occurrences of the target may be safely replaced.

Available Expression Analysis Eliminating CSEs

Global Common Subexpression Elimination

code motion

One important alteration that decreases the amount of code in a loop is

code optimization

The process of tuning the output of a compiler to minimize or maximize some attributes of an executable computer program.

strength reduction.

The transformation of replacing an expensive operation, such as multiplication, by a cheaper one, such as addition, is known as _____

Available expressions

across basic blocks Provide the set of available expressions at each block header

machine-independent code-optimization phase

attempts to improve the intermediate code so that better target code will result.

Optimization

can be done in almost all phases of compilation.

loop optimization

can have a significant impact because many programs spend a large percentage of their time inside loops.

Copy propagation

is a useful "clean up" optimization frequently used after other optimizations have already been run.

Copy Propagation

is the process of replacing the occurrences of targets of direct assignments with their values.

Dead Code Elimination

is to remove code which does not affect the program results

Common-subexpression elimination, copy propagation, dead-code elimination, and constant folding

number of ways in which a compiler can improve a program without changing the function it computes.

local optimization

reduces the amount of analysis that needs to be performed it saves time and reducestorage requirements

Value Numbering

within a basic block Initialize value table with available expressions

induction variable

A variable x is said to be an ______ if there is a positive or negative constant c such that each time x is assigned, its value increases by c.