test/hotspot/jtreg/compiler/splitif/TestSplitDivisionThroughPhi.java

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/**
* @test
* @key stress randomness
* @bug 8299259
* @requires vm.compiler2.enabled
* @summary Test various cases of divisions/modulo which should not be split through iv phis.
* @run main/othervm -Xbatch -XX:+UnlockDiagnosticVMOptions -XX:LoopUnrollLimit=0 -XX:+StressGCM -XX:StressSeed=884154126
*                   -XX:CompileCommand=compileonly,compiler.splitif.TestSplitDivisionThroughPhi::*
*                   compiler.splitif.TestSplitDivisionThroughPhi
*/

/**
* @test
* @key stress randomness
* @bug 8299259
* @requires vm.compiler2.enabled
* @summary Test various cases of divisions/modulo which should not be split through iv phis.
* @run main/othervm -Xbatch -XX:+UnlockDiagnosticVMOptions -XX:LoopUnrollLimit=0 -XX:+StressGCM
*                   -XX:CompileCommand=compileonly,compiler.splitif.TestSplitDivisionThroughPhi::*
*                   compiler.splitif.TestSplitDivisionThroughPhi
*/

package compiler.splitif;

public class TestSplitDivisionThroughPhi {
    static int iFld;
    static long lFld;
    static boolean flag;


    public static void main(String[] strArr) {
        for (int i = 0; i < 5000; i++) {
            testPushDivIThruPhi();
            testPushDivIThruPhiInChain();
            testPushModIThruPhi();
            testPushModIThruPhiInChain();
            testPushDivLThruPhi();
            testPushDivLThruPhiInChain();
            testPushModLThruPhi();
            testPushModLThruPhiInChain();
        }
    }

    // Already fixed by JDK-8248552.
    static void testPushDivIThruPhi() {
        for (int i = 10; i > 1; i -= 2) {
            // The Div node is only split in later loop opts phase because the zero divisor check is only removed
            // in IGVN after the first loop opts phase.
            //
            // iv phi i type: [2..10]
            // When splitting the DivI through the iv phi, it ends up on the back edge with the trip count decrement
            // as input which has type [0..8]. We end up executing a division by zero on the last iteration because
            // the DivI it is not pinned to the loop exit test and can freely float above the loop exit check.
            iFld = 10 / i;
        }
    }

   // Same as above but with an additional Mul node between the iv phi and the Div node. Both nodes are split through
   // the iv phi in one pass of Split If.
    static void testPushDivIThruPhiInChain() {
        for (int i = 10; i > 1; i -= 2) {
            // Empty one iteration loop which is only removed after split if in first loop opts phase. This prevents
            // that the Mul node is already split through the iv phi while the Div node cannot be split yet due to
            // the zero divisor check which can only be removed in the IGVN after the first loop opts pass.
            for (int j = 0; j < 1; j++) {
            }
            iFld = 10 / (i * 100);
        }
    }

    // Already fixed by JDK-8248552.
    static void testPushModIThruPhi() {
        for (int i = 10; i > 1; i -= 2) {
            iFld = 10 / i;
        }
    }

    // Same as above but with ModI.
    static void testPushModIThruPhiInChain() {
        for (int i = 10; i > 1; i -= 2) {
            for (int j = 0; j < 1; j++) {
            }
            iFld = 10 / (i * 100);
        }
    }

    // Long cases only trigger since JDK-8256655.

    // Same as above but with DivL.
    static void testPushDivLThruPhi() {
        for (long i = 10; i > 1; i -= 2) {
            lFld = 10L / i;

            // Loop that is not removed such that we do not transform the outer LongCountedLoop (only done if innermost)
            for (int j = 0; j < 10; j++) {
                flag = !flag;
            }
        }
    }

    // Same as above but with DivL.
    static void testPushDivLThruPhiInChain() {
        for (long i = 10; i > 1; i -= 2) {
            for (int j = 0; j < 1; j++) {
            }
            lFld = 10L / (i * 100L);

            for (int j = 0; j < 10; j++) {
                flag = !flag;
            }
        }
    }

    // Same as above but with ModL
    static void testPushModLThruPhi() {
        for (long i = 10; i > 1; i -= 2) {
            lFld = 10L % i;

            for (int j = 0; j < 10; j++) {
                flag = !flag;
            }
        }
    }

    // Same as above but with ModL
    static void testPushModLThruPhiInChain() {
        for (long i = 10; i > 1; i -= 2) {
            for (int j = 0; j < 1; j++) {
            }
            lFld = 10L % (i * 100L);

            for (int j = 0; j < 10; j++) {
                flag = !flag;
            }
        }
    }
}