loopinv.dcf

用Java实现的编译器。把源代码编译成SPARC汇编程序

// loop invariant code motion

class Program {

  int gl;
  int ai[1];


  boolean foo(int inp) {
    gl = gl + 1;
    inp = inp + 1;
    return (inp < 14);
  }

  void main() {
    int a,b,c,d,e,f;

    gl = 0;
    ai[0] = -1;

    callout("printf","A? ");
    a = callout("readint");

    callout("printf","B? ");
    b = callout("readint");

    callout("printf","C? ");
    c = callout("readint");

    while (foo((a+b)+gl)) { // the a+b should be moved
      f = f + 1; // should not be moved
      c = a + b; // may be moved;
      d = gl + b; // should not be moved
      e = f + b;  // should not be moved
    }

    while (f < 0) {
      d = -1;    // should be moved but not executed since f < 0 is false.
      f = ai[0]; // bounds check can be moved, but not the failure jump
    }
    callout("printf", "a: %d  ", a);
    callout("printf", "b: %d  ", b);
    callout("printf", "c: %d  ", c);
    callout("printf", "d: %d  ", d);
    callout("printf", "e: %d  ", e);
    callout("printf", "f: %d  ", f);
    callout("printf", "gl: %d\n", gl);
      

  }
}