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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
 *
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package org.graalvm.compiler.phases.contract;

import java.util.ArrayList;
import java.util.List;
import java.util.function.Function;

import org.graalvm.compiler.core.common.cfg.BlockMap;
import org.graalvm.compiler.debug.CounterKey;
import org.graalvm.compiler.debug.DebugContext;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.VerificationError;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.cfg.Block;
import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
import org.graalvm.compiler.phases.schedule.SchedulePhase;

import jdk.vm.ci.meta.ResolvedJavaMethod;

public class NodeCostUtil {

    private static final CounterKey sizeComputationCount = DebugContext.counter("GraphCostComputationCount_Size");
    private static final CounterKey sizeVerificationCount = DebugContext.counter("GraphCostVerificationCount_Size");

    @SuppressWarnings("try")
    public static int computeGraphSize(StructuredGraph graph) {
        sizeComputationCount.increment(graph.getDebug());
        int size = 0;
        for (Node n : graph.getNodes()) {
            size += n.estimatedNodeSize().value;
        }
        assert size >= 0;
        return size;
    }

    @SuppressWarnings("try")
    public static double computeGraphCycles(StructuredGraph graph, boolean fullSchedule) {
        Function<Block, Iterable<? extends Node>> blockToNodes;
        ControlFlowGraph cfg;
        if (fullSchedule) {
            SchedulePhase schedule = new SchedulePhase(SchedulePhase.SchedulingStrategy.LATEST_OUT_OF_LOOPS, true);
            schedule.apply(graph);
            cfg = graph.getLastSchedule().getCFG();
            blockToNodes = b -> graph.getLastSchedule().getBlockToNodesMap().get(b);
        } else {
            cfg = ControlFlowGraph.compute(graph, true, true, false, false);
            BlockMap<List<FixedNode>> nodes = new BlockMap<>(cfg);
            for (Block b : cfg.getBlocks()) {
                ArrayList<FixedNode> curNodes = new ArrayList<>();
                for (FixedNode node : b.getNodes()) {
                    curNodes.add(node);
                }
                nodes.put(b, curNodes);
            }
            blockToNodes = b -> nodes.get(b);
        }
        double weightedCycles = 0D;
        DebugContext debug = graph.getDebug();
        try (DebugContext.Scope s = debug.scope("NodeCostSummary")) {
            for (Block block : cfg.getBlocks()) {
                for (Node n : blockToNodes.apply(block)) {
                    double probWeighted = n.estimatedNodeCycles().value * block.probability();
                    assert Double.isFinite(probWeighted);
                    weightedCycles += probWeighted;
                    if (debug.isLogEnabled()) {
                        debug.log("Node %s contributes cycles:%f size:%d to graph %s [block prob:%f]", n, n.estimatedNodeCycles().value * block.probability(),
                                        n.estimatedNodeSize().value, graph, block.probability());
                    }
                }
            }
        }
        assert weightedCycles >= 0D;
        assert Double.isFinite(weightedCycles);
        return weightedCycles;
    }

    private static int deltaCompare(double a, double b, double delta) {
        if (Math.abs(a - b) <= delta) {
            return 0;
        }
        return Double.compare(a, b);
    }

    
Factor to control the "imprecision" of the before - after relation when verifying phase
effects. If the cost model is perfect the best theoretical value is 0.0D (Ignoring the fact
that profiling information is not reliable and thus the, probability based, profiling view on
a graph is different than the reality).
/**
     * Factor to control the "imprecision" of the before - after relation when verifying phase
     * effects. If the cost model is perfect the best theoretical value is 0.0D (Ignoring the fact
     * that profiling information is not reliable and thus the, probability based, profiling view on
     * a graph is different than the reality).
     */
    private static final double DELTA = 0.001D;

    public static void phaseFulfillsSizeContract(StructuredGraph graph, int codeSizeBefore, int codeSizeAfter, PhaseSizeContract contract) {
        sizeVerificationCount.increment(graph.getDebug());
        final double codeSizeIncrease = contract.codeSizeIncrease();
        final double graphSizeDelta = codeSizeBefore * DELTA;
        if (deltaCompare(codeSizeAfter, codeSizeBefore * codeSizeIncrease, graphSizeDelta) > 0) {
            ResolvedJavaMethod method = graph.method();
            double increase = (double) codeSizeAfter / (double) codeSizeBefore;
            throw new VerificationError("Phase %s expects to increase code size by at most a factor of %.2f but an increase of %.2f was seen (code size before: %d, after: %d)%s",
                            contract.contractorName(), codeSizeIncrease, increase, codeSizeBefore, codeSizeAfter,
                            method != null ? " when compiling method " + method.format("%H.%n(%p)") + "." : ".");
        }
    }

}