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 * Copyright (c) 2016, Oracle 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
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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.Debug;
import org.graalvm.compiler.debug.DebugCounter;
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.nodes.spi.NodeCostProvider;
import org.graalvm.compiler.phases.schedule.SchedulePhase;

import jdk.vm.ci.meta.ResolvedJavaMethod;

public class NodeCostUtil {

    private static final DebugCounter sizeComputationCount = Debug.counter("GraphCostComputationCount_Size");
    private static final DebugCounter sizeVerificationCount = Debug.counter("GraphCostVerificationCount_Size");

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

    @SuppressWarnings("try")
    public static double computeGraphCycles(StructuredGraph graph, NodeCostProvider nodeCostProvider, 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;
        try (Debug.Scope s = Debug.scope("NodeCostSummary")) {
            for (Block block : cfg.getBlocks()) {
                for (Node n : blockToNodes.apply(block)) {
                    double probWeighted = nodeCostProvider.getEstimatedCPUCycles(n) * 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, nodeCostProvider.getEstimatedCPUCycles(n) * block.probability(),
                                        nodeCostProvider.getEstimatedCodeSize(n), 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();
        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)") + "." : ".");
        }
    }

}