CS 453 Programming Assignment #2 — MiniJava and MIPS warmup

Introduction

The Assignment

For this assignment, you need to implement the following functions in MIPS:

• void _printint(int): Prints given integer followed by a newline

• void* _localtest(int n): Allocates space for 4 local variables and returns the address where the nth local variable is located. n will be a number in the range 1..4.

• void* _halloc(int n): Allocates n consecutive bytes in the heap and returns the address of the first byte allocated. (Hint: sbrk syscall)

We will be using the same stack frame layout as is used in the code generated by the Wisconsin C-- Compiler. This is because in CS 553, we use the C-- compiler to help implement garbage collection for MiniJava. The stack frame layout you must implement is as follows:

• Each function must store $ra and $fp.
• The frame pointer $fp should be made to point at the first incoming parameter for the current function.
• Formals and locals should be stored in declaration order.
• The stack pointer $sp should point at the next empty spot on the stack.
• The caller should push parameters in order onto the stack.
• The callee should pop its own parameters off the stack before it returns.
• The callee should put the return value in $v0.
• The caller should retrieve the return value from $v0.

$fp_main -->  |  $ra   |
              |  $fp   |
              | locals |
              | ...    |
$fp_func -->  | arg1   |
              | arg2   |
              | ...    |
              | $ra    |
              | $fp    |
              | locals |
              | ...    |
$sp  -->      | empty  |

You also need to implement the following programs in MiniJava and in MIPS. When running the MiniJava program using javac and java, you should get the same results as running the MIPS program through SPIM. These programs are so simple that we will be looking at the code to makes sure the actual computation is being done.

• Factorial.java and Factorial.s: Implement the factorial function and call it on the number 5.
• ObjectFun.java and ObjectFun.s: Allocate space on the heap for two object instances of a class with an integer member variable and a boolean member variable.

      struct MyClass {
          int i;
          bool b;
      };
  

  In the first instance set i to 7 and b to true. In the second instance set i to 42 and b to false. Then print the value of both fields in both object instances: one value per line.

    % java -classpath java-cup-11a-runtime.jar -jar MJParser.jar Program.java

Getting Started

## helloworld.s
    .text
    .globl main
main:
    sw      $ra, 0($sp)     # PUSH
    subu    $sp, $sp, 4
    sw      $fp, 0($sp)     # PUSH
    subu    $sp, $sp, 4

    addu    $fp, $sp, 8     # point fp to first parameter, no params for main
    subu    $sp, $fp, 8     # size of frame = 4 + 4 + 4*numparams + 4*numlocals

    # print Hello World!

    # the number put into $v0 selects SPIM syscall
    # parameter should be passed in $a0
    la      $a0, hello_world
    li      $v0, 4
    syscall

exit_main:
    lw      $ra, 0($fp)
    move    $t0, $fp
    lw      $fp, -4($fp)
    move    $sp, $t0
    jr      $ra

        .data
hello_world:    .asciiz "Hello World!\n"

  > /s/bach/b/class/cs553/spim-7.2.1-keepstats/spim/spim -keepstats helloworld.s

Some other examples to look at include sum5_all.s and readprint.s. sum5_all.s requires that you concatenate the implementation for printint to the file before running it.

Read the Appendix A: Assemblers, Linkers, and the SPIM Simulator from the third edition of Hennessy and Patterson, Computer Organization and Design: The Hardware/Software Interface for a description of various MIPS instructions and how to use SPIM system calls.

Submitting:

Preliminary Subversion Log

• Submit a subversion_username.txt file containing output from svn log and svn info with the checkin utility

  ~cs453/bin/checkin PA2_svnlog subversion_username.txt

Assignment

• Make sure you test your implementation thoroughly.
• Only turnin one assignment per group.
• Use subversion to export a copy of your assignment.
• Include all the funcname.s files, all the MiniJava source files, a README file, and a subversion.txt file in a tar file.

  tar cf PA2_username.tar PA2

  • The README file should include your username(s), emails(s), and any information you want the TA to have before grading your assignment. E.g., this part is not working due to..., a favorite quote or joke to amuse the TA, etc.
  • The subversion.txt file should include output from the following:

    svn log -r HEAD:1
    svn info
    svnlook tree REPOSITORY_PATH  svnlook must be issued on a department machine
        

• Submit assignment using checkin utility.

  ~cs453/bin/checkin PA2 PA2_username.tar

• Sanity Check (procedure TA will use to run your assignment):

  tar xf PA2_username.tar
  cd PA2
  
  cat printint.s halloc.s localtest.s stackframe-testdriver.s > all.s
  spim all.s
  
  javac Factorial.java
  java Factorial > Factorial.java.out
  spim Factorial.s > Factorial.s.out
  diff Factorial.s.out Factorial.java.out
    

  ObjectFun will be tested in the same way as Factorial. The extra output that spim generates:

  SPIM Version 7.2.1 of August 28, 2005
  Copyright 1990-2004 by James R. Larus (larus@cs.wisc.edu).
  All Rights Reserved.
  See the file README for a full copyright notice.
  Loaded: /usr/local/share/xspim/CPU/exceptions.s
  

  will be ignored.

Late Policy