LoopSafepointEliminationPhase.java revision 12968:4d8a004e5c6d 
1/*
2 * Copyright (c) 2011, 2013, Oracle and/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 */
23package org.graalvm.compiler.loop.phases;
24
25import org.graalvm.compiler.loop.LoopEx;
26import org.graalvm.compiler.loop.LoopsData;
27import org.graalvm.compiler.nodes.FixedNode;
28import org.graalvm.compiler.nodes.Invoke;
29import org.graalvm.compiler.nodes.LoopEndNode;
30import org.graalvm.compiler.nodes.StructuredGraph;
31import org.graalvm.compiler.nodes.cfg.Block;
32import org.graalvm.compiler.nodes.extended.ForeignCallNode;
33import org.graalvm.compiler.phases.BasePhase;
34import org.graalvm.compiler.phases.tiers.MidTierContext;
35
36public class LoopSafepointEliminationPhase extends BasePhase<MidTierContext> {
37
38    @Override
39    protected void run(StructuredGraph graph, MidTierContext context) {
40        LoopsData loops = new LoopsData(graph);
41        if (context.getOptimisticOptimizations().useLoopLimitChecks(graph.getOptions()) && graph.getGuardsStage().allowsFloatingGuards()) {
42            loops.detectedCountedLoops();
43            for (LoopEx loop : loops.countedLoops()) {
44                if (loop.loop().getChildren().isEmpty() && loop.counted().getStamp().getBits() <= 32) {
45                    boolean hasSafepoint = false;
46                    for (LoopEndNode loopEnd : loop.loopBegin().loopEnds()) {
47                        hasSafepoint |= loopEnd.canSafepoint();
48                    }
49                    if (hasSafepoint) {
50                        loop.counted().createOverFlowGuard();
51                        loop.loopBegin().disableSafepoint();
52                    }
53                }
54            }
55        }
56        for (LoopEx loop : loops.loops()) {
57            for (LoopEndNode loopEnd : loop.loopBegin().loopEnds()) {
58                Block b = loops.getCFG().blockFor(loopEnd);
59                blocks: while (b != loop.loop().getHeader()) {
60                    assert b != null;
61                    for (FixedNode node : b.getNodes()) {
62                        if (node instanceof Invoke || (node instanceof ForeignCallNode && ((ForeignCallNode) node).isGuaranteedSafepoint())) {
63                            loopEnd.disableSafepoint();
64                            break blocks;
65                        }
66                    }
67                    b = b.getDominator();
68                }
69            }
70        }
71        loops.deleteUnusedNodes();
72    }
73}
74