SRS_CODEOPTIMISER

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A

PROJECT REPORT

ONCODE OPTIMIZATION

Submitted By, Guided By,

Akshat Mishra Mr. Ranjeet Jaiswal

Anuj M Khasgiwala Lecturer, CSE.

Arpit Jain

Narendra Shakya

Team Number- A10

Oriental Institute of Science & Technology, Bhopal

Department of Computer Science & Engineering

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Table of Contents

1. Introduction 3 1.1 About the project 4

1.2 Objective 4

2. Classification of Optimization 5

3. Problem Definition 10

3.1 Existing System

11

3.2 Proposed System

11

4. System Study 12

4.1 System Development Life Cycle

12

4.2 Software Model

13

5. Requirement Specification 15

5.1 Feasibility Study

15

5.2 Hardware Requirement

16

5.3 Software Requirement

16

6. Design 17

6.1 Input Requirement

17

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6.2 Data Flow Diagram

17

6.3 Control Flow Diagram

18

6.4 System Flow Diagram19

7. Conclusion 20

8. Reference 20

1. INTRODUCTION

Compiler optimization is the process of tuning the output of a compiler to minimize or

maximize some attributes of an executable computer program. The most common requirement

is to minimize the time taken to execute a program; a less common one is to minimize the

amount of memory occupied. In computing, optimization is the process of modifying a system

to make some aspect of it work more efficiently or use fewer resources. There are broadly two

types of optimizations

1. Memory optimization

2. Speed optimization

Memory:

The program created need to be compact in order to use less memory space.Code optimiser

aims at minimising the code length and removing unnecessary codes or variables.

Speed:

There are two types of programs those that need to be fast and those that don't. With ever

increasing speed of processors and peripherals more applications fall into the latter category.

Of those where speed is critical there are several possible bottlenecks:

Hard disk & File system Network Operating system kernel

Languages standard library Users

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Memory Processor

Code optimization can be also broadly categorized as

1. Platform dependent

2. Platform independent techniques

While the latter ones are effective on most or all platforms, platform dependent techniques

use specific properties of one platform, or rely on parameters depending on the single

platform or even on the single processor; writing or producing different versions of thesame code for different processors might be thus needed.

1.1 THE OVERVIEW OF PROJECT:

Code Optimizer is software which optimizes a program. In computing, Optimization is the

process of modifying a system to make some aspect of it work more efficiently or use fewer

resources. For instance, a computer program may be optimized so that it executes more rapidly,

or is capable of operating with less memory storage or other resources, or draw less power. The

system may be a single computer program, a collection of computers or even an entire network

such as the Internet. See also algorithmic efficiency for further discussion on factors relating to

improving the efficiency of an algorithm.

1.2 OBJECTIVES

The main goal or objective behind preparing for this project is to optimize the code which

makes it more efficient in reference to space usage and time complexity. It is a technique

which is mainly used to optimize the code in order to get the best output as early as

possible. Code optimizer aims to optimize-

Execution time

Not important if the program execution time is very short

Important in High Performance Computing where execution times may

be very long (days, weeks or months).

Also very important in many embedded systems, where there may be

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strict requirements on the execution time

Memory usage

This is part of normal algorithm design

The memory requirements of an algorithm are fairly easy to understand Corresponds directly to the data structures allocated in the program

Power consumption

Very important in mobile systems and embedded systems

2. CLASSIFICATION OF OPTIMIZATION

There are so many Optimization technique it is worthwhile to reduce the complexity of their

study. Two useful classifications are:

The time during compilation process when an optimization can be applied.

The area of the program over which the optimization applies.

Optimization can be performed at practically every stage of compilation. Example: the constant

folding can be performed as early as during parsing. Some optimization can be delayed until

after target code has been generated.-target code is examined and rewritten to reflect

optimization.

The classification scheme for optimization that we consider is by area of the program over

which the optimization applies. It is divided into fellow category:

Local optimization.

Global optimization.

Inter-Procedural optimization.

Local Optimization

Major local optimization strategies are:

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1. Dead code Elimination: A variable is live at a point in a program If it can be used

subsequently. Similarly the statements that never get execute or never compute values are

called the dead code.

Example:

Void main ()

{

int a;

a=5;

cout


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cout


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A typical example of this is the replacement of arithmetic operation by cheaper

operation. Such as multiplication by 2 can be implemented as a shift operation and as

small integer power such as x3 can be implemented as a multiplication such as x*x*x.

This optimization Is called Reduction in strength.

4. Constant Folding:

In compiler theory, constant folding and constant propagation are related

optimization techniques used by many modern compilers. A more advanced form of

constant propagation known as sparse conditional constant propagation may be utilized to

simultaneously remove dead code and more accurately propagate constants. Constant

folding is the process of simplifying constant expressions at compile time. Terms in

constant expressions are typically simple literals, such as the integer 2, but can also be

variables whose values are never modified, or variables explicitly marked as constant.

Consider the statement:-

i = 320 * 200 * 32;

Most modern compilers would not actually generate two multiply instructions and a

store for this statement. Instead, they identify constructs such as these, and substitute the

computed values at compile time (in this case, 2,048,000), usually in the intermediate

representation (IR) tree. In some compilers, constant folding is done early so that

statements such as C's array initializers can accept simple arithmetic expressions. However,

it is also common to include further constant folding rounds in later stages in the compiler,

as well. Constant folding can be done in a compiler's front end on the IR tree that represents

the high-level source language, before it is translated into three-address code, or in the back

end, as an adjunct to constant propagation.

Global Optimization

Optimization that extend beyond basic blocks but are confined to an individual procedure.

Global optimization is an extend form of the local optimization it is more difficult to

perform.

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They are generally required a techniques called data flow analysis which attempts to

collect information across jump boundaries.

Global optimization uses the same techniques that are used in the local optimization.

But instead of considering the basic block global optimization consider the complete

procedure as a processed block.

Global Sub-Expression Elimination: An occurrence of an expression E is called Global

sub=expression if E was previously computed and the values of variables in E have not

changed since the previous computation. So we can avoid the recomputation if we can use the

previous value.

Inter-Procedural Optimization

Optimizations that extend beyond the boundaries to the entire program are called Inter-

procedural Optimization.

It is even more difficult since it involves possible several different parameters passing

mechanisms the possibility of non-local variables access and the need to compute

simultaneous information on all procedure that might call each other.

An additional compilation is the possibility that many procedures may be compiles

separately and only linked together at a later point.

The complier then cannot perform any inter-procedural optimization at all without the

involvement of a specialized form of linker that carries out optimization based on

information that the compiler has gathered.

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3. PROBLEM DEFINITION

In the execution of any program, user may face several problems. Our project will

eliminate these problems, as follows-

Dead code Elimination - Dead Code Elimination is an optimization technique to

eliminate some variables not used at all. The variables which are useless in a program

will detect and eliminate by the optimizer.

Common Sub-Expression Elimination - Common sub expression elimination 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.

Loop Optimization - Loop optimization plays an important role in improving cache

performance, making effective use of parallel processing capabilities, and reducing

overheads associated with executing loops. Most execution time of a scientific program

is spent on loops. Thus a lot of compiler analysis and compiler optimization techniqueshave been developed to make the execution of loops faster.

Strength Reduction - Strength reduction is a compiler optimization where expensive

operations are replaced with equivalent but less expensive operations. The classic

example of strength reduction converts "strong" multiplications inside a loop into

"weaker" additions something that frequently occurs in array addressing.

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Constant Folding- Constant folding and constant propagation are related compiler

optimizations used by many modern compilers. An advanced form of constant

propagation known as sparse conditional constant propagation can more accurately

propagate constants and simultaneously remove dead code.

Elimination of useless instruction - Some instructions that do not modify any memory

storage can be detect and removed by optimizer.

3.1 Existing System:

There are some existing compilers in market, as follows-

Microsoft C, QuickC - Microsoft

Open Watcom- Sybase

XL C IBM Turbo C Embarcadero

Open64- Google, HP, Intel, Nvidia, PathScale and others.

3.2 Proposed System:

The proposed system is developed with the aim to overcome the drawbacks of existing

system. The proposed system has got some advantages. People from different parts of the

world can run their programs very easily. It is more personalized and maze in such a manner

that any user can understand all the options in it very easily. It is made in a quick and easy

referential manner for providing the optimized code.

It can be run easily at the time of optimization. Some of the advantages of proposed system are

as follows,

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A Simple but effective technique for locally improving the target code is peephole

optimization.

A method for trying to improve the performance of the target program.

By examining a short sequence of target instructions and replacing these instructions by

a shorter or faster sequence whenever possible.

4. SYSTEM STUDY

The system study phase involves the initial investigation of the structure of the System,

which is currently in use, with the objective of identifying the problem and difficulties with the

existing system. The major steps involved in this phase included defining the user requirements

and studying the present system to verify the problem. The performance expected by the new

system was also defined in this phase in order to meet the user requirements. The information

gathered from various documents were analyzed and evaluated and the findings reviewed in

order to establish specific system objectives.

4.1 System development life cycle (SDLC)

The Systems Development Life Cycle (SDLC) or Software Development Life Cycle in

systems engineering and software engineering is the process of creating or altering systems,

and the models and methodologies that people use to develop these systems. The concept

generally refers to computer or information systems.

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Systems Development Life Cycle (SDLC) is any logical process used by a systems analyst

to develop an information system, including requirements, validation, training, and user

ownership. A SDLC should result in a high quality system that meets or exceeds customer

expectations, reaches completion within time and cost estimates, works effectively and

efficiently in the current and planned Information Technology infrastructure, and is

inexpensive to maintain and cost-effective to enhance.

Below we have shown the software development life cycle of our project Code Optimizer.

4.2 SOFTWARE MODEL

INCREMENTAL MODEL:

Incremental development is a cyclic software development process developed in

response to the weaknesses of the waterfall model. It starts with an initial planning and ends

with deployment with the cyclic interaction in between.

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The basic idea behind iterative enhancement is to develop a software systemincrementally, allowing the developerto take advantage of what was being learned during the

development of earlier, incremental, deliverable versions of the system. Learning comes fromboth the development and use of the system, where possible. Key steps in the process were to

start with a simple implementation of a subset of the software requirements and iteratively

enhance the evolving sequence of versions until the full system is implemented. At eachiteration, design modifications are made and new functional capabilities are added.

The Procedure itself consists of the Initialization step, the Iteration step, and the Project

Control List. The initialization step creates a base version of the system. The goal for thisinitial implementation is to create a product to which the user can react. It should offer asampling of the key aspects of the problem and provide a solution that is simple enough to

understand and implement easily. To guide the iteration process, a project control list is

created that contains a record of all tasks that need to be performed. It includes such items asnew features to be implemented and areas of redesign of the existing solution. The control

list is constantly being revised as a result of the analysis phase.

The iteration involves the redesign and implementation of a task from the project control

list, and the analysis of the current version of the system. The goal for the design andimplementation of any iteration is to be simple, straightforward, and modular, supporting

redesign at that stage or as a task added to the project control list. The level of design detail isnot dictated by the interactive approach. In a light-weight iterative project the code may

represent the major source of documentation of the system; however, in a mission-criticaliterative project a formal Software Design Document may be used. The analysis of iteration

is based upon user feedback, and the program analysis facilities available. It involves

analysis of the structure, modularity, usability, reliability, efficiency, & achievement ofgoals. The project control list is modified in light of the analysis results.

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5. REQUIREMENT SPECIFICATION

The primary goal of the system analyst is to improve the efficiency of the existing system. For

that the study of specification of the requirements is very essential. For the development of the

new system, a preliminary survey of the existing system will be conducted. Investigation done

whether the up gradation of the system into an application program could solve the problems

and eradicate the inefficiency of the existing system.

5.1 FEASIBILITY STUDY

The initial investigation points to the question whether the project is feasible. A

feasibility is conducted to identify the best system that meets the all the requirements. This

includes an identification description, an evaluation of the proposed systems and selection of

the best system for the job

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The requirements of the system are specified with a set of constraints such as system objectives

and the description of the out puts. It is then duty of the analyst to evaluate the feasibility of the

proposed system to generate the above results. Three key factors are to be considered during

the feasibility study.

Operation Feasibility:

An estimate should be made to determine how much effort and care will go into the

developing of the system including the training to be given to the user. Usually, people are

reluctant to changes that come in their progression. The computer initialization will certainly

affected the turn over, transfer and employee job status. Hence an additional effort is to be

made to train and educate the users on the new way of the system.

Technical Feasibility:

The main consideration is to be given to the study of available resources of the

organization where the software is to be implemented. Here the system analyst evaluates the

technical merits of the system giving emphasis on the performance, reliability, maintainability.

By taking the consideration before developing the proposed system, the resources availability

of the organization was studied. The organization was immense computer facilities equipped

with sophisticated machines and the software hence this technically feasible.

Economic Feasibility:

Economic feasibility is the most important and frequently used method for evaluating

the effectiveness of the proposed system. It is very essential because the main goal of the

proposed system is to have economically better result along with increased efficiency. Cost

benefit analysis is usually performed for this purpose. It is the comparative study of the costverses the benefit and savings that are expected from the proposed system. Since the

organization is well equipped with the required hard ware, the project was found to be

economically.

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5.2 HARDWARE REQUIREMENT

Pantium-2/3 processor

128 RAM

1GB hard disk

5.3 SOFTWARE REQUIREMENT

Development End Text Pad , Net beans , JAVA 1.6

Operating System Windows XP/98

6. DESIGN

6.1 INPUT REQUIREMENT

In our project, we have to input a program written in C programming language.This

can be done in two ways:

1. User can provide the input by specifying filename i.e. C format.

2. User can provide the input by writing a C program on Code Window.

6.2 DATA FLOW DIAGRAM

LEVEL O:

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LEVEL 1:

6.3 CONTROL FLOW DIAGRAM

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USER Dead VariableElimination

Dead Code

Eliminatio

n

Common Sub

expression

Elimination

Constant

Folding

Code

Motion

Strength

Reduction

Optimized

Output


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User

Start/Stop

Exit

OptimizedCode

Start/Stop

Input Code

Elimination

Process

Dead variable / Deadcode

Loop Optimization

Exit


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6.4 SYSTEM FLOW DIAGRAM

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Optimized

Code

OutputInterface

OperatorInterface

Input Choice

Operator

Interface

Operation

DiagnosticsSubsystem

CodeChecking InductionVariable SubsystemApplication

Subsystem

SelectionLanguage

Subsystem

Website Creation

Interface

Input CodeSubsystem

CheckingLoops

Subsystem

Error in codeInputInterface

DiagnosticInterface


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7. CONCLUSION

The Code Optimization is developed using Java and fully meets the objectives of the

system for which it has been developed. The system has reached a steady state where all errors

have been eliminated. The system is operated at a high level of efficiency and all the userassociated with the system understands its advantage. The system solves the problem. It was

intended to solve as requirement specification.

8. REFERENCE

Compiler in C

Ullman and Sethi. Google

Wikipedia

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