ICS 142 Homework 7 Due 5/31

(30 points) Use loop-unrolling and other techniques to hand-optimize the following block as much as possible. Show each step and explain what optimization technique you applied in each step.
```
DECLARE
  x: integer := 0;
  y: integer := 3;
BEGIN
  FOR i IN 1..y LOOP
    x := x+1;
  END LOOP;
  put(x);
END;
```
(70 points) Write a C++ program to do the following
- build a list of instructions from three address code generated by your Tiny-Ada compiler. You may use my start on the parser in http://www.ics.uci.edu/~klefstad/s/142/src//hw7/three_address.[ylh].
- use the reaching definitions to perform the following optimizations (optimize as much as possible):
  - constant propagation
  - copy propagation
  - constant folding
  - eliminating useless assignments
- print the optimized three-address code in the standard format.

You need only handle the operators plus (+) and times (*). Treat all uninitialized variables as unknown until run-time (similar to parameters or variables initialized to dynamic values) to make this problem more realistic.

Here is another example input program (example 1):
  X := 1
  Y := 1
  X := X + Y
  Y := X + 1
  put Y
Here is the output after optimization:
  put 3
Here is another example input program (example 2):
  get Y
  get X
  X := Y + 1
  Y := X * 2
  put X
  put Y
The output is the same as the input since no optimization can be done.