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/**

 * @test

 * @bug 8139771

 * @summary Eliminating CastPP nodes at Phis when they all come from a unique input may cause crash

 * @requires vm.gc=="Serial" | vm.gc=="Parallel"

 *

 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement

 *      -XX:+UnlockDiagnosticVMOptions -XX:+IgnoreUnrecognizedVMOptions -XX:+StressGCM

 *      compiler.controldependency.TestEliminatedCastPPAtPhi

 *

 */

package compiler.controldependency;

public class TestEliminatedCastPPAtPhi {

    static TestEliminatedCastPPAtPhi saved;

    static TestEliminatedCastPPAtPhi saved_not_null;

    int f;

    static int test(TestEliminatedCastPPAtPhi obj, int[] array, boolean flag) {

        int ret = array[0] + array[20];

        saved = obj;

        if (obj == null) {

            return ret;

        }

        saved_not_null = obj;

        // empty loop to be optimized out. Delays range check smearing

        // for the array access below until the if diamond is

        // optimized out

        int i = 0;

        for (; i < 10; i++);

        ret += array[i];

        TestEliminatedCastPPAtPhi res;

        if (flag) {

            // load is optimized out and res is obj here

            res = saved;

        } else {

            // load is optimized out and res is non null CastPP of res here

            res = saved_not_null;

        }

        // null check + CastPP here for res field load below

        // 1) null check is pushed in the branches of the if above by

        // split through phi because res is non null in the second

        // branch and the null check can be optimized out in that

        // branch. The Castpp stays here.

        // 2) null check in the first branch is also optimized out

        // because a dominating null check is found (the explicit null

        // check at the beggining of the test)

        // 3) the Phi for the if above merges a CastPP'ed value and

        // the same value so it's optimized out and replaced by the

        // uncasted value: obj

        // 4) the if above has 2 empty branches so it's optimized

        // out. The control of the CastPP that is still here is now

        // the success branch of the range check for the array access

        // above

        // 5) the loop above is optimized out, i = 10, the range check

        // for the array access above is optimized out and all its

        // uses are replaced by the range check for the array accesses

        // at the beginning of the method. The castPP here is one of

        // the uses and so its control is now the range check at the

        // beginning of the method: the control of the CastPP bypasses

        // the explicit null check

        return ret + res.f;

    }

    static public void main(String[] args) {

        int[] array = new int[100];

        TestEliminatedCastPPAtPhi obj = new TestEliminatedCastPPAtPhi();

        for (int i = 0; i < 20000; i++) {

            test(obj, array, (i%2) == 0);

        }

        test(null, array, true);

    }

}