UMBC CMSC431, Compiler Design Principles, Fall 2009

News Archive

• [Thu Dec 03 00:22 2009]
  Homework 5 posted.

• [Wed Nov 25 14:31 2009]
  Project 7 has been posted.

• [Fri Nov 20 00:35 2009]
  Posted p6test13.c.

• [Fri Nov 20 00:35 2009]
  Here are some links for material on garbage collection:

  • Documentation from Sun on tuning the garbage collector in Java SE 6.

  • A series of three articles from IBM on garbage collection in Java. These articles, written in 2003-2004, are a bit dated but give a good overview of garbage collection.
    • Java theory and practice: A brief history of garbage collection
    • Java theory and practice: Garbage collection in the HotSpot JVM
    • Java theory and practice: Garbage collection and performance

  • Steffen Garup and Jacob Seligmann. "Incremental Mature Garbage Collection," M.Sc. Thesis, Computer Science Department, Aarhus University, Denmark, August 1993. Available by anonymous ftp at ftp.daimi.au.dk/pub/thesis/gcthesis.ps.gz.

• [Mon Nov 16 07:40 2009]
  Test programs for Project 6 have been posted:

  Translate the following C programs into your programming language. (Note: the first 10 of these programs are just short programs to see if your compiler is doing type checking for function calls and return statements correctly. They should result in syntax errors.) You should compile and run the C program and check if it produces the same answers as code generated by your compiler.

  • Type mismatch errors: p6test01.c, p6test02.c, p6test03.c, p6test04.c, p6test05.c, p6test06.c, p6test07.c, p6test08.c, p6test09.c and p6test10.c.

  • Testing basic function calls: p6test11.c.

  • Testing recursive function calls (Euclid's Algorithm): p6test12.c.

  Note: the assumption is that your compiler handled the test programs from Project 5 correctly. Thus, none of these test programs check that local variables are handled correctly. If your Project 5 did not handle local variables, please make sure that you submit the test programs from Project 5 as well.

• [Fri Nov 13 23:05 2009]
  The assembly language programs shown in class on Tuesday have been fixed up and posted. These programs demonstrate how function calls are made and how values are returned from the functions. See Returning values from functions.

• [Thu Nov 12 07:50 2009]
  Homework 4 posted.

• [Tue Nov 10 02:05 2009]
  Project 6 has been posted.

• [Fri Nov 06 23:46 2009]
  Here's the assembly language program shown in class on Thursday: switch.asm. It is a hand-written assembly program that shows what the output of a compiled switch statement might look like.

• [Tue Oct 27 12:41 2009]
  Reminder: there are no office hours this Wednesday (10/28) and Thursday (10/29). I can be available Friday if you need debugging help. Also, no class on Thursday (10/29).

• [Tue Oct 27 02:50 2009]
  Project 5 is assigned.

• [Tue Oct 27 01:10 2009]
  Homework 3 posted.

• [Thu Oct 15 04:30 2009]
  Posted an explanation of how to resolve reduce/reduce conflicts created by mid-action rules and the dangling else problem: Mid-Rule Actions and the Dangling Else.

• [Thu Oct 15 00:55 2009]
  Homework 2 posted.

• [Tue Oct 13 00:20 2009]
  Project 4 is assigned.

• [Tue Oct 06 01:45 2009]
  Project 3 is assigned.

• [Thu Oct 01 09:55 2009]
  Homework 1 posted.

• [Thu Sep 24 12:16 2009]
  Fixed up the last line of ch3-03.l. If you copied that file, you should use the new copy.

• [Tue Sep 22 09:25 2009]
  Project 2 is assigned.

• [Fri Sep 18 00:25 2009]
  Here's an example of the program I mentioned in class on Thursday: bomb.c and bomb.txt. In this program, the function foo() overruns a local array by a single 4-byte entry. Unfortunately, this is exactly where the base pointer EBP for the main function is stored. In the sample run, you see that the segmentation fault does not occur until control has returned to the main program and the main program tries to access a local variable. (Even the call to printf() after the call to foo() is executed without a problem!) It is difficult to find these bugs because the error is not where the program crashed.

• [Thu Sep 17 14:15 2009]
  Here's the source files for the assembly language example programs that use the x87 Floating Point Unit (FPU):

  • The first program, we just want to print out a floating point number: double1.asm and double1.txt.

    Note that the MOV instruction does not support memory to memory moves, so you cannot say:

    mov [esp], DWORD [pi] That's why I copied 4-bytes of pi to the EAX register and then pushed it onto the stack. This takes more steps than using the FLD and FSTP floating-point instructions.

  • In the second and third programs, we test what happens if we push more than 8 numbers on the FPU register stack. First we just try pushing 3 numbers (double2.asm and double2.txt). No problem there. Then, we try pushing 10 numbers (double3.asm and double3.txt). In this case, we see that the stack wraps around and messes up the first two registers. Here the "nan" printed out means "not a number".

  • The fourth program demonstrates the ordinary use of the floating-point arithmetic instructions on values placed in the FPU register stack: (double4.asm and double4.txt). Note that the "pop" forms of the instructions (e.g., FADDP, FSUBP, FMULP) are quite convenient when we want to take two numbers from the top of the stack and replace them with the result of the arithmetic operation.

  • The last program shows what you have to do for floating-point comparisons. (double5.asm and double5.txt). Since there isn't a list of floating-point conditional jump insructions, we have to move the FPU's status register to the AX register and do some bit-manipulations. This is done using the FSTSW and TEST instructions.

• [Thu Sep 17 01:24 2009]
  My mistake: looks like there isn't really a National Talk Like a Pirate Week (Arg!!!) but this Saturday, September 19th, is indeed Talk Like a Pirate Day.

• [Thu Sep 17 12:47 2009]
  Here are the slides from this morning's lecture: cs431week3.pdf (slightly updated) and FPU.pdf.

• [Tue Sep 15 12:47 2009]
  Here are the slides from this morning's lecture: cs431week3.pdf

  The slides were take from my Fall 2004 CMSC313 class and represent about 5 lectures of materials. You can look at the original lecture notes here. (Click on the topic for a synopsis of what was covered and "actual" to see the slides for that day.)

  The short tutorial on using gdb to debug assembly language programs is here.

• [Fri Sep 11 12:12 2009]
  Code from Thursday's lecture:
  • A yacc program that converts an arithmetic expression from infix to postfix: postfix.y and postfix.txt. (Use with ch3-01.l.)
  • A yacc program that shows how to use %left and %right to indicate associativity and precdence of operators: ch3-02.y and ch3-02.txt. (Use with ch3-01.l.)
  • Lex and yacc programs that allow assignment to single character variables. Note how %union is used in conjunction with %token, %left, %right and %type to declare the type of tokens and nonterminals. Also, note the use of union type field names in the lex program: ch3-03.l, ch3-03.y and ch3-03.txt.

• [Tue Sep 08 15:08 2009]
  Updated links to NASM.

• [Tue Sep 08 09:20 2009]
  Project 1 is assigned.

• [Tue Sep 08 13:20 2009]
  Code from today's lecture:
  • First lex program & output: hello.l and hello.txt.
  • The second lex program prints out "number" when the input matches the pattern for a floating point number: ch2-01.l and ch2-01.txt.
  • This lex program counts the number of characters, words and lines in an input file: ch2-02.l and ch2-02.txt.
  • A very simple lex and yacc program that does addition and subtraction: ch3-01.l, ch3-01.y and ch3-01.txt.

• [Tue Sep 08 12:07 2009]
  If you don't have a copy of the Flex & Bison book (or the older Lex & Yacc book), there are several online sources of documentation for Flex and Bison:
  • The Lex & Yacc page: http://dinosaur.compilertools.net/.
  • The Bison Manual by Donnelly and Stallman:
    • Online: http://www.gnu.org/software/bison/manual/.
    • Local copy in PDF: Bison_Manual_2.4.1.pdf.
  • "Lex — A Lexical Analyzer Generator" by Lesk and Schmidt:
    • Online: http://dinosaur.compilertools.net/lex/index.html.
    • Local copy in PDF: Lex_Manual.pdf.
  • "Flex — a fast scanner generator" by Paxson:
    • Online: http://dinosaur.compilertools.net/flex/index.html.
    • Local copy in PDF: Flex_Manual.pdf.
  If you just want the documentation on syntax for regular expressions in flex, go here.

• [Tue Sep 08 11:50 2009]
  Office hours on Wed 9/9 will be shifted to 10:30am – 11:30am.

• [Thu Sep 03 15:05 2009]
  Oops, that was the CMSC441 syllabus! It's fixed now.

• [Thu Sep 03 15:05 2009]
  If you lost your printed copy of the course description and syllabus, it's here: 431description.pdf.

• [Tue Sep 01 23:45 2009]
  Web page up.