We noticed that the test program below fails.

The arraycopy call has to throw an IndexOutOfBoundsException because the length is -1. We can see this happening when we switch off EliminateAllocations (or DoEscapeAnalysis).

Seems like PhaseMacroExpand::process_users_of_allocation removes the ArrayCopyNode without checking the parameters. After the ArrayCopyNode is removed, the parameters are no longer checked and no exception is thrown.

TestArrayCopyMinusOne.java
public class TestArrayCopyMinusOne{

    public boolean do_test() {
        try {
            System.arraycopy(new Object[1], 1, new Object[1], 1, -1);
            return false;
        } catch (IndexOutOfBoundsException e) {
            return true;
        }
    }

 
   static final int loop_cnt=100000;

   public static void main(String args[]){
       TestArrayCopyMinusOne xyz = new TestArrayCopyMinusOne();
       int errors = 0;
       long duration = System.nanoTime();
       for (int x = 0; x < loop_cnt; x++) {
           if (!xyz.do_test()) errors++;
       }
       duration = System.nanoTime() - duration;
       System.out.println("errors: " + errors + " (duration: " + duration/loop_cnt + ")");
   }

}