Project 9: Compilation

In this project, you will complete a compiler for Jay (called JaySea, inspired by javac) which produces Java VM assembly (which can then be used to generate classfiles).

Take note that we are compiling plain old Jay, not any of the Jay extensions we've played with this semester.

1. Set-up.

Many other pieces are provided for you, and can be found in a tar file.

cp /cslab/class/cs365/proj10.tar .

The system works like this. The script jaysea feeds a Jay program into the ML-written compiler, which produces a file in Java VM assembly. For example,

./jaysea euclid.jay

will produce euclid.jj. Then the Java assembler Jasmin can be used to produce the classfile. For example,

java -jar /cslab/java/classes/jasmin.jar euclid.jj

or, if jasmin.jar is already in your classpath,

java Jasmin euclid.jj

will produce euclid.class. Now

java euclid

Will run the program.

2. Your task

Your task is finishing the compilation functions in compile.sml. As in Friday's class, what you need to figure out is, for all Jay statements and expressions, what series of instructions needs to be emitted, and how does that affect the stack?

3. Suggestions

Make use of these resources:

• The Jasmin Home Page, especially the description of instructions.
• The Java VM Spec, especially the VM instruction set (Notice the alphabetical indices at the top of the page.)

As you work, I recommend you have both Jay and Java versions of your test files. Compile the Java versions and disassemble them with javap to see what the result might look like. Your output does not have to be identical to what javac produces--often there is an equivalent series of instructions that you'll find are easier to produce---but javac can guide you through some of the knottier statements.

4. Extra credit

All you need is a compiler that produces programs that work to get full credit. But there are some optimizations you could perform for which I will award extra credit. For example, if (x > 0)... would naively be complied by loading x, pushing 0, generating the sequence for >, and then ifne, but a more efficient version woul load x and use if_icmpgt. Also, x = x + 1; could be done using the iinc instruction.

5. To turn in

To turn in this project, please copy your compile.sml to the turn=in directory I will prepare for you: /cslab/class/cs365/turnin/proj10/xxxxx

where "xxxxx" is [andy|david|tyler|yelemis].

Due: May 2, 5:00 pm. You may not apply late days to this project; all projects must be turned in by this, the last day of classes.