CS 4120/4121/5120/5121 : Introduction to Compilers
Spring 2021

Announcements

• In Spring 2021, this course may be taken either in-person (possibly hybrid depending on the lecture room size) or remotely. More signups should be available in the near future. If you have your heart set on being in the course, it should be possible to be in the class even if only remotely.
• Frequently asked questions:
  1. I didn't enroll in the course in December. Can I still join the course? Almost certainly. You can add yourself to the course waitlist when the add/drop period begins (during Feb 2–5, depending on your year). Note that only CS students were allowed to enroll in 4000/5000-level courses during preregistration.
  2. When does CS 4121/5121 meet? At the same time as CS 4120/5120.
  3. Is there any difference between 4120 and 5120? The latter is for MEng students and requires a little more work on the project.
  4. Is this course going to be similar to last time? Yes.
  5. When will this course be offered next? It is planned to be offered next in Spring 2022, although this is not guaranteed. If not, it should be offered in Spring 2023.

Overview

An introduction to the specification and implementation of modern compilers. Topics covered include lexical scanning, parsing, type checking, code generation and translation, an introduction to optimization, and compile-time and run-time support for modern programming languages.  As part of the course, students build a working compiler for an object-oriented language.

Course information

Course Staff

The best way to reach the course staff is normally by posting on the discussion forum. We will be using Ed Discussions for this purpose. However, for private correspondence you can email individual staff members. Please do not ask multiple course staff members the same question privately via email; that just wastes our time. Piazza is normally the right way to ask questions about course content or assignments.

Prerequisites

Computer Science 3110 and either CS 3410 or 3420. The practicum (CS 4121 or 5121) is a required co-requisite. You may not take CS 4120 without taking CS 4121 too, and similarly for CS 5120 and CS 5121. The reason for this is that the group project is part of the grade for both 4120 and 4121. Familiarity with programming in Java is also expected.

Most project groups choose to use Java to implement their compiler; however, other languages may be used with the permission of the instructor. It is strongly encouraged to use a language with a strong, static type system and automatic garbage collection.

Course Meetings

Lectures are MWF 3:45–4:35 in Martha Van Rensselaer Hall (MVR), room 1101. Seating will be assigned to students so they can attend at least two of the three lectures in person. Please consult the seating diagram for the room. On the day you can't attend, or if you are taking the class online, you should use the Zoom meeting.

Recorded videos for lectures can also be found at the video channel for the course.

Texts

You are required to read the course notes posted on the web site. These will often contain more detail than what was presented in lecture.

There is no required textbook this semester, but the following textbooks will be helpful sources of information. All of these books will be available on reserve in Uris Library.

• Modern Compiler Implementation in Java, 2nd ed. Andrew Appel and Jens Palsberg, Cambridge University Press, 2002. ISBN 0-521-82060-X.
• Compilers—Principles, Techniques and Tools (The “Dragon Book”), 2nd ed. Alfred Aho, Monica Lam, Ravi Sethi and Jeffrey D. Ullman. Addison-Wesley, 2006. ISBN: 0-321-48681-1
• Engineering a Compiler. Keith Cooper and Linda Torczon. Elsevier/Morgan Kaufmann, 2004. ISBN 1-55860-698-8.
• Advanced Compiler Design and Implementation. Steve Muchnick. Morgan Kaufmann Publishers, 1997. ISBN 1-558-60320-4.

The Java language specification may also be useful to you either online or in its printed form:

• The Java Language Specification. James Gosling, Bill Joy, and Guy Steele. Addison-Wesley, 1996. ISBN 0-201-63451-1

Another useful text, on linking and loading, is:

• Linkers and Loaders. John R. Levine. Morgan Kaufman, 1999. ISBN 1-55860-496-0

Here are a couple of useful books on coding and software engineering:

• Design Patterns: Elements of Reusable Object-Oriented Software. Gamma, Helm, Johnson, Vlissides, Booch. Addison-Wesley, 1995. ISBN 0-201-63361-2
• Refactoring: Improving the Design of Existing Code. Martin Fowler. Addison-Wesley, 1999. ISBN 0-201-48567-2.

Coursework

Assignments and Grading

There are four written homework assignments. You may discuss assignments with other students, but the work must be done on an individual basis. The names of any students you discussed the problems with must be recorded with the corresponding problems.

The compiler project is divided up into seven programming assignments that are due at various points throughout the term. Compiler projects will be performed by groups of three or four students. The same groups will be maintained throughout the semester, if possible.

Except in unusual circumstances, you will receive the same grade in CS 4120 and CS 4121 (resp. 5120 and 5121), and all members of a group will receive the same grade on programming assignments. Exceptions to these rules are dealt with on a case-by-case basis.

Participation includes attending and participating in class (either in-person or remotely), asking good questions on the forum, answering questions on the forum, and filling out the course evaluation form.

The breakdown of points per assignment is as follows:

The weighted quadratic mean of these scores will be used to determine the final score in the course. The main effect of a quadratic mean is to make unusually low scores count for less and unusually high scores count for more. It usually affects the grades of at most a handful of students.

Assignment late penalties:

We are flexible about submitting assignments late. You will have six slip days that may be used during the semester to submit work without penalty. Using more than six slip days will lead to significant penalties on subsequent assignments. Any penalties applied will be on an individual basis. Weekends are considered to be a single day for the purpose of computing slip days.

Slip day usage may be avoided or reduced by obtaining an extension on the assignment. Extension requests should be made via email; copying all group members on the request. They should include a description of why an extension is being requested. Extension requests based on foreseeable events will normally be denied; slip days exist to provide this scheduling flexibility.

Exams

The prelims will cover material from the textbook, lectures, and homework assignments. Both prelims will be evening exams. There will be no final exam, but your final report and demo will be due on the first day of finals.

Other components

We expect you to participate in class and elsewhere. 2% of the score will be for class participation (in-class, Piazza, course evals) and for possible in-class pop quizzes.

Academic Integrity

The Cornell Code of Academic Integrity will be strictly enforced in this class. A Cornell student's submission of work for academic credit indicates that the work is the student's own. All outside assistance must be acknowledged, and students' academic position must be truthfully reported at all times. We take cheating and fraud very seriously.

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Resources

• Course notes
• Java language
• Programming advice and resources
• Computer labs
• Support services

Assignments

Homework

• Homework 1: Lexical Analysis
• Homework 2: Syntactic Analysis
• Homework 3: Semantic Analysis
• Homework 4: Program Analysis

Programming Assignments

• Programming Assignment 1: Implementing Lexical Analysis
• Programming Assignment 2: Implementing Syntactic Analysis [pretty-printer documentation]
• Programming Assignment 3: Implementing Semantic Analysis
• Programming Assignment 4: Intermediate Code Generation
• Programming Assignment 5: Assembly Code Generation
• Programming Assignment 6: Optimization