jdk/test/hotspot/jtreg/compiler/igvn/CmpDisjointButNonOrderedRanges.java

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/**
 * @test
 * @bug 8360561
 * @summary Ranges can be proven to be disjoint but not orderable (thanks to unsigned range)
 *          Comparing such values in such range with != should always be true.
 * @run main/othervm -Xcomp
 *                   -XX:CompileCommand=compileonly,compiler.igvn.CmpDisjointButNonOrderedRanges::*
 *                   compiler.igvn.CmpDisjointButNonOrderedRanges
 * @run main compiler.igvn.CmpDisjointButNonOrderedRanges
 */
package compiler.igvn;

public class CmpDisjointButNonOrderedRanges {
    static boolean bFld;

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

    static void test() {
        int x = 7;
        int y = 4;
        for (int i = 3; i < 12; i++) {
            // x = 7 \/ x = -195 => x \in [-195, 7] as a signed value
            // but [7, bitwise_cast_uint(-195)] as unsigned
            // So 0 is not possible.
            if (x != 0) {
                A.foo();
                // Because A is not loaded, A.foo() traps and this point is not reachable.
            }
            // x is tighten to be in the meet (so Hotspot's join) of [0, 0] and [7, bitwise_cast_uint(-195)]
            // that is bottom (Hotspot's top). Data is dead, control needs to be dead as well.
            for (int j = 1; j < 8; j++) {
                x = -195;
                if (bFld) {
                    y += 2;
                }
            }
        }
    }

    static void foo() {
    }
}


class A {
    static void foo() {
    }
}