FloatingPointFoldingTest.java

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/**
 * @test
 * @bug 8073670
 * @summary Test that causes C2 to fold two NaNs with different values into a single NaN.
 *
 * @run main/othervm -XX:-TieredCompilation -Xcomp
 *      -XX:CompileCommand=compileonly,compiler.c2.FloatingPointFoldingTest::test_double_inf
 *      -XX:CompileCommand=compileonly,compiler.c2.FloatingPointFoldingTest::test_double_zero
 *      -XX:CompileCommand=compileonly,compiler.c2.FloatingPointFoldingTest::test_double_nan
 *      -XX:CompileCommand=compileonly,compiler.c2.FloatingPointFoldingTest::test_float_inf
 *      -XX:CompileCommand=compileonly,compiler.c2.FloatingPointFoldingTest::test_float_zero
 *      -XX:CompileCommand=compileonly,compiler.c2.FloatingPointFoldingTest::test_float_nan
 *      compiler.c2.FloatingPointFoldingTest
 */

package compiler.c2;

public class FloatingPointFoldingTest {
    // Double values.
    public static final long MINUS_INF_LONGBITS = 0xfff0000000000000L;
    public static final double DOUBLE_MINUS_INF = Double.longBitsToDouble(MINUS_INF_LONGBITS);

    public static final long PLUS_INF_LONGBITS = 0x7ff0000000000000L;
    public static final double DOUBLE_PLUS_INF = Double.longBitsToDouble(PLUS_INF_LONGBITS);

    public static final long MINUS_ZERO_LONGBITS = 0x8000000000000000L;
    public static final double DOUBLE_MINUS_ZERO = Double.longBitsToDouble(MINUS_ZERO_LONGBITS);

    // We need two different NaN values. A floating point number is
    // considered to be NaN is the sign bit is 0, all exponent bits
    // are set to 1, and at least one bit of the exponent is not zero.
    //
    // As java.lang.Double.NaN is 0x7ff8000000000000L, we use
    // 0x7ffc000000000000L as a second NaN double value.
    public static final long NAN_LONGBITS = 0x7ffc000000000000L;
    public static final double DOUBLE_NAN = Double.longBitsToDouble(NAN_LONGBITS);

    // Float values.
    public static final int MINUS_INF_INTBITS = 0xff800000;
    public static final float FLOAT_MINUS_INF = Float.intBitsToFloat(MINUS_INF_INTBITS);

    public static final int PLUS_INF_INTBITS = 0x7f800000;
    public static final float FLOAT_PLUS_INF = Float.intBitsToFloat(PLUS_INF_INTBITS);

    public static final int MINUS_ZERO_INTBITS = 0x80000000;
    public static final float FLOAT_MINUS_ZERO = Float.intBitsToFloat(MINUS_ZERO_INTBITS);

    // As java.lang.Float.NaN is 0x7fc00000, we use 0x7fe00000
    // as a second NaN float value.
    public static final int NAN_INTBITS = 0x7fe00000;
    public static final float FLOAT_NAN = Float.intBitsToFloat(NAN_INTBITS);


    // Double tests.
    static void test_double_inf(long[] result) {
        double d1 = DOUBLE_MINUS_INF;
        double d2 = DOUBLE_PLUS_INF;
        result[0] = Double.doubleToRawLongBits(d1);
        result[1] = Double.doubleToRawLongBits(d2);
    }

    static void test_double_zero(long[] result) {
        double d1 = DOUBLE_MINUS_ZERO;
        double d2 = 0;
        result[0] = Double.doubleToRawLongBits(d1);
        result[1] = Double.doubleToRawLongBits(d2);
    }

    static void test_double_nan(long[] result) {
        double d1 = DOUBLE_NAN;
        double d2 = Double.NaN;
        result[0] = Double.doubleToRawLongBits(d1);
        result[1] = Double.doubleToRawLongBits(d2);
    }

    // Float tests.
    static void test_float_inf(int[] result) {
        float f1 = FLOAT_MINUS_INF;
        float f2 = FLOAT_PLUS_INF;
        result[0] = Float.floatToRawIntBits(f1);
        result[1] = Float.floatToRawIntBits(f2);
    }

    static void test_float_zero(int[] result) {
        float f1 = FLOAT_MINUS_ZERO;
        float f2 = 0;
        result[0] = Float.floatToRawIntBits(f1);
        result[1] = Float.floatToRawIntBits(f2);
    }

    static void test_float_nan(int[] result) {
        float f1 = FLOAT_NAN;
        float f2 = Float.NaN;
        result[0] = Float.floatToRawIntBits(f1);
        result[1] = Float.floatToRawIntBits(f2);
    }

    // Check doubles.
    static void check_double(long[] result, double d1, double d2) {
        if (result[0] == result[1]) {
            throw new RuntimeException("ERROR: Two different double values are considered equal. \n"
                                       + String.format("\toriginal values: 0x%x 0x%x\n", Double.doubleToRawLongBits(d1), Double.doubleToRawLongBits(d2))
                                       + String.format("\tvalues after execution of method test(): 0x%x 0x%x", result[0], result[1]));
        }
    }

    // Check floats.
    static void check_float(int[] result, float f1, float f2) {
        if (result[0] == result[1]) {
            throw new RuntimeException("ERROR: Two different float values are considered equal. \n"
                                       + String.format("\toriginal values: 0x%x 0x%x\n", Float.floatToRawIntBits(f1), Float.floatToRawIntBits(f2))
                                       + String.format("\tvalues after execution of method test(): 0x%x 0x%x", result[0], result[1]));
        }
    }

    public static void main(String[] args) {
        // Float tests.

        int[] iresult = new int[2];

        // -Inf and +Inf.
        test_float_inf(iresult);
        check_float(iresult, FLOAT_MINUS_INF, FLOAT_PLUS_INF);

        // 0 and -0.
        test_float_zero(iresult);
        check_float(iresult, FLOAT_MINUS_ZERO, 0);

        // Diferrent NaNs.
        test_float_nan(iresult);
        check_float(iresult, FLOAT_NAN, Float.NaN);

        // Double tests.

        long[] lresult = new long[2];

        // -Inf and +Inf.
        test_double_inf(lresult);
        check_double(lresult, DOUBLE_MINUS_INF, DOUBLE_PLUS_INF);

        // 0 and -0.
        test_double_zero(lresult);
        check_double(lresult, DOUBLE_MINUS_ZERO, 0);

        // Diferrent NaNs.
        test_double_nan(lresult);
        check_double(lresult, DOUBLE_NAN, Double.NaN);
    }
}