1 /*
 2  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  *
23  */
24 
25 #include "precompiled.hpp"
26 #include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
27 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
28 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
29 #include "logging/log.hpp"
30 #include "logging/logTag.hpp"
31 #include "runtime/globals_extension.hpp"
32 
33 void ShenandoahGenerationalMode::initialize_flags() const {
34 
35 #if !(defined AARCH64 || defined AMD64 || defined IA32 || defined PPC64)
36   vm_exit_during_initialization("Shenandoah Generational GC is not supported on this platform.");
37 #endif
38 
39   // Exit if the user has asked ShenandoahCardBarrier to be disabled
40   if (!FLAG_IS_DEFAULT(ShenandoahCardBarrier)) {
41     SHENANDOAH_CHECK_FLAG_SET(ShenandoahCardBarrier);
42   }
43 
44   // Enable card-marking post-write barrier for tracking old to young pointers
45   FLAG_SET_DEFAULT(ShenandoahCardBarrier, true);
46 
47   if (ClassUnloading) {
48     FLAG_SET_DEFAULT(VerifyBeforeExit, false);
49   }
50 
51   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(GCTimeRatio, 70);
52   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
53   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
54 
55   // This helps most multi-core hardware hosts, enable by default
56   SHENANDOAH_ERGO_ENABLE_FLAG(UseCondCardMark);
57 
58   // Final configuration checks
59   SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
60   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
61   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
62   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
63   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCardBarrier);
64 }