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package compiler.loopopts;

import compiler.lib.ir_framework.*;
import compiler.lib.ir_framework.driver.irmatching.IRViolationException;
import jdk.test.lib.Asserts;

/*
 * @test
 * @bug 8371685
 * @requires vm.flagless & vm.debug
 * @summary Verifies that the LoopPeeling flag correctly disables loop peeling
 *          by checking whether the "After Loop Peeling" compile phase is
 *          emitted.  When loop peeling is disabled, no peeling should occur and
 *          the phase must be absent from the compilation output.
 * @library /test/lib /
 * @run driver compiler.loopopts.TestLoopPeelingDisabled
 */
public class TestLoopPeelingDisabled {
    static int[] array = new int[100];

    public static void main(String[] args) {
        // First, run the test with loop peeling enabled, which is the default.
        // The IR framework should catch if the number of counted loops does not
        // match the annotations.
        TestFramework.run();

        // Then, run the same test with loop peeling disabled, which should
        // elide the {BEFORE,AFTER}_LOOP_PEELING compilation phases, causing the
        // test to throw an IRViolationException. We then check whether the
        // exception message matches our expectation (that the loop peeling
        // phase was not found).
        try {
            TestFramework.runWithFlags("-XX:+UnlockDiagnosticVMOptions",
                                       "-XX:LoopPeeling=0");
            Asserts.fail("Expected IRViolationException");
        } catch (IRViolationException e) {
            String info = e.getExceptionInfo();
            if (!info.contains("NO compilation output found for this phase")) {
                Asserts.fail("Unexpected IR violation: " + info);
            }
            System.out.println("Loop peeling correctly disabled");
        }

        // Finally, run the same test with loop peeling disabled only when
        // splitting iterations.  Since the function being tested does not hit
        // this case, we expect that the loop will be peeled, which is ensured
        // by the IR annotations.
        TestFramework.runWithFlags("-XX:+UnlockDiagnosticVMOptions",
                                   "-XX:LoopPeeling=2");
    }

    @Test
    @IR(counts = {IRNode.COUNTED_LOOP, "1"}, phase = CompilePhase.BEFORE_LOOP_PEELING)
    @IR(counts = {IRNode.COUNTED_LOOP, "2"}, phase = CompilePhase.AFTER_LOOP_PEELING)
    public static int test() {
        int sum = 0;

        // Use an odd trip count so that `do_maximally_unroll()` tries to peel
        // the odd iteration.
        for (int i = 0; i < 5; i++) {
            sum += array[i];
        }

        return sum;
    }
}