test/hotspot/jtreg/compiler/loopopts/TestSinkingDivisorLostPin.java

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/*
 * @test
 * @key stress randomness
 * @bug 8274074
 * @requires vm.compiler2.enabled
 * @summary Sinking a data node used as divisor of a DivI node into a zero check UCT loses its pin outside the loop due to
 *          optimizing the CastII node away, resulting in a div by zero crash (SIGFPE) due to letting the DivI node floating
 *          back inside the loop.
 * @run main/othervm -Xcomp -XX:CompileCommand=compileonly,compiler.loopopts.TestSinkingDivisorLostPin::* -XX:-TieredCompilation
 *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressGCM -XX:StressSeed=4177789702 compiler.loopopts.TestSinkingDivisorLostPin
 * @run main/othervm -Xcomp -XX:CompileCommand=compileonly,compiler.loopopts.TestSinkingDivisorLostPin::* -XX:-TieredCompilation
 *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressGCM compiler.loopopts.TestSinkingDivisorLostPin
 */

package compiler.loopopts;

public class TestSinkingDivisorLostPin {
    static int iFld = 1;
    static int x = 1;
    static int q = 0;
    static int iArrFld[] = new int[100];

    public static void main(String[] strArr) {
        test();
    }

    static void test() {
        int y = 1;
        int i = 1;
        do {
            int j;
            for (j = 1; j < 88; j++) {
                iArrFld[1] = x;
            }
            try {
                y = iFld - q; // y = 1 - 0
                y = (iArrFld[2] / y); // y = iArrFld[2] / 1
                // Zero check Z1 with UCT
                // DivI node D on IfTrue path of zero check
                y = (5 / iFld); // y = 5 / 1
                // Zero check Z2 with UCT
                // DivI node D is only used on IfFalse path of zero check Z2 into UCT (on IfTrue path, the result is not used anywhere
                // because we directly overwrite it again with "y = (5 / iFld)). The IfFalse path of the zero check, however, is never
                // taken because iFld = 1. But before applying the sinking algorithm, the DivI node D could be executed during the
                // loop, as the zero check Z1 succeeds. Only after sinking the SubI node for "iFld - q" into the IfFalse path of Z2
                // and optimizing it accordingly (iFld is found to be zero because the zero check Z2 failed, i.e. iFld is zero which is
                // propagated into the CastII node whose type is improved to [0,0] and the node is replaced by constant zero), the
                // DivI node must NOT be executed inside the loop anymore. But the DivI node is executed in the loop because of losing
                // the CastII pin. The fix is to update the control input of the DivI node to the get_ctrl() input outside the loop
                // (IfFalse of zero check Z2).
            } catch (ArithmeticException a_e) {
            }

            iFld -= 8;
            if (y == 3) {
            }
            i++;
        } while (i < 10);
    }

}