TestEliminateAllocationPhi.java

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/*
 * @test
 * @bug 8046698
 * @summary PhiNode inserted between AllocateNode and Initialization node confuses allocation elimination
 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement
 *                   compiler.macronodes.TestEliminateAllocationPhi
 */

package compiler.macronodes;

public class TestEliminateAllocationPhi {

    // This will return I when called from m(0 and once optimized will
    // go away but this will confuse escape analysis in m(): it will
    // find I as non escaping but non scalar replaceable. In its own
    // method so that we can make the profile of the if() branch look
    // like it's taken sometimes.
    static Integer m2(Integer I, int i) {
        for (; i < 10; i=(i+2)*(i+2)) {
        }
        if (i == 121) {
            return II;
        }
        return I;
    }

    static Integer II = new Integer(42);

    static int m(int[] integers, boolean flag) {
        int j = 0;
        while(true) {
            try {
                int k = integers[j++];
                // A branch that will cause loop unswitching
                if (flag) {
                    k += 42;
                }
                if (k < 1000) {
                    throw new Exception();
                }
                // Because of the try/catch the Allocate node for this
                // new will be in the loop while the Initialization
                // node will be outside the loop. When loop
                // unswitching happens, the Allocate node will be
                // cloned and the results of both will be inputs to a
                // Phi that will be between the Allocate nodes and the
                // Initialization nodes.
                Integer I = new Integer(k);

                I = m2(I, 0);

                int i = I.intValue();
                return i;
            } catch(Exception e) {
            }
        }
    }

    static public void main(String[] args) {
        for (int i = 0; i < 5000; i++) {
            m2(null, 1);
        }

        int[] integers = { 2000 };
        for (int i = 0; i < 6000; i++) {
            m(integers, (i%2) == 0);
        }
        int[] integers2 = { 1, 2, 3, 4, 5, 2000 };
        for (int i = 0; i < 10000; i++) {
            m(integers2, (i%2) == 0);
        }
    }
}