test/hotspot/jtreg/compiler/intrinsics/string/TestStringConstruction.java

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/*
 * @test
 * @bug 8142303
 * @summary Tests handling of invalid array indices in C2 intrinsic if explicit range check in Java code is not inlined.
 *
 * @run main/othervm
 *      -XX:CompileCommand=inline,java.lang.String::*
 *      -XX:CompileCommand=inline,java.lang.StringUTF16::*
 *      -XX:CompileCommand=exclude,java.lang.String::checkBoundsOffCount
 *      compiler.intrinsics.string.TestStringConstruction
 */

package compiler.intrinsics.string;

public class TestStringConstruction {

    public static void main(String[] args) {
        char[] chars = new char[42];
        for (int i = 0; i < 10_000; ++i) {
            test(chars);
        }
    }

    private static String test(char[] chars) {
        try {
            // The constructor calls String::checkBoundsOffCount(-1, 42) to perform
            // range checks on offset and count. If this method is not inlined, C2
            // does not know about the explicit range checks and does not cut off the
            // dead code. As a result, -1 is fed as offset into the StringUTF16.compress
            // intrinsic which is replaced by TOP and causes a failure in the matcher.
            return new String(chars, -1 , 42);
        } catch (Exception e) {
            return "";
        }
    }
}