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/*
* Copyright (c) 2025, Red Hat and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 8344251
* @summary Test that blackhole without control input are removed
* @library /test/lib /
* @run driver compiler.blackhole.DeadBhElimination
*/
package compiler.blackhole;
import compiler.lib.ir_framework.*;
public class DeadBhElimination {
public static void main(String[] args) {
TestFramework.runWithFlags(
"-XX:-TieredCompilation",
"-XX:+UnlockExperimentalVMOptions",
// Prevent the dead branches to be compiled into an uncommon trap
// instead of generating a BlackholeNode.
"-XX:PerMethodTrapLimit=0",
"-XX:PerMethodSpecTrapLimit=0",
"-XX:CompileCommand=blackhole,compiler.blackhole.DeadBhElimination::iAmABlackhole"
);
}
static public void iAmABlackhole(int x) {}
@Test
@IR(counts = {IRNode.BLACKHOLE, "1"}, phase = CompilePhase.AFTER_PARSING)
@IR(failOn = {IRNode.BLACKHOLE}, phase = CompilePhase.FINAL_CODE)
static void removalAfterLoopOpt() {
int a = 77;
int b = 0;
do {
a--;
b++;
} while (a > 0);
// b == 77, known after first loop opts round
// loop is detected as empty loop
if (b == 78) { // dead
iAmABlackhole(a);
}
}
}
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