Exploring Compilation

Summary: Today, you will explore various issues in compilation. While you have used a compiler before (or I hope you have), I expect you haven't thought much about various options and details.

Disclaimer: You come to this lab with widely varying backgrounds. Some of you have programmed in C, some of you haven't; some of you have written (or read) some assembly language, some of you haven't; some of you are Unix experts, some of you aren't. Don't worry if you can't finish the lab (or if you finish it in five minutes).

Collaboration: Feel free to work on this lab in pairs or trios.

Turning It In: Save your answers in a plain text file and email it to me.

Grading: I expect that you will gain more from doing this lab than from me grading this lab. I will simply scan through your answers to see if you had any particularly valuable insights.

Preparation:

Make a copy of today's files with

cvs -d  /home/rebelsky/Web/Courses/CS362/2004S/CVS checkout Lab01

You will find that you now have a directory called Lab01.

Questions:

• 1. GCC's Stages
• 2. A Sample C Program
• 3. C vs. Pascal
• 4. GCC's Intermediate Representations, Revisited
  • GCC Source

1. GCC's Stages

Read information on the GNU Compiler Collection (gcc) and determine which of its intermediate program representations are available to you. You might use man or info to learn more about gcc.

Summarize the intermediate representations available to you.

2. A Sample C Program

Generate intermediate representations from twos.c and scan through those that you can read.

What, if anything, did you learn about the intermediate representations?

3. C vs. Pascal

The programs hellop.p and helloc.c print the phrase Hello World. Generate assembly for both programs.

Note that you may have to use the Pascal compiler (pc) on lovelace.

How do the results differ? How are they similar?

4. GCC's Intermediate Representations, Revisited

Look on the Web for internal documentation on GCC. Explore which, if any, internal program representations are available to those building new GCC compilers.

Describe, in as much detail as you deem appropriate, the intermediate representations available and their purpose.

GCC Source

If you think it might be useful, you can find a copy of the GCC source code at /home/rebelsky/Web/Courses/Examples/gcc-3.2.tar.gz. You can find a list of files in that archive with

% zcat gztarfile | tar tvf - | less

You can extract a particular file with

% zcat gztarfile | tar xvf - file