/*
 * Copyright (c) 2015, 2015, 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.
 *
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package com.oracle.graal.lir.ssa;

import java.util.*;

import com.oracle.graal.api.code.*;
import com.oracle.graal.compiler.common.cfg.*;
import com.oracle.graal.lir.*;
import com.oracle.graal.lir.gen.*;
import com.oracle.graal.lir.phases.*;
import com.oracle.jvmci.options.*;

public final class SSADestructionPhase extends PreAllocationOptimizationPhase {

    public static class Options {
        // @formatter:off
        @Option(help = "Destruct SSA LIR eagerly (before other LIR phases).", type = OptionType.Debug)
        public static final OptionValue<Boolean> LIREagerSSADestruction = new OptionValue<>(false);
        // @formatter:on
    }

    @Override
    protected <B extends AbstractBlockBase<B>> void run(TargetDescription target, LIRGenerationResult lirGenRes, List<B> codeEmittingOrder, List<B> linearScanOrder, LIRGeneratorTool lirGen) {
        LIR lir = lirGenRes.getLIR();
        AbstractControlFlowGraph<?> cfg = lir.getControlFlowGraph();
        for (AbstractBlockBase<?> block : cfg.getBlocks()) {
            doBlock(block, lir, lirGen);
        }
    }

    private static void doBlock(AbstractBlockBase<?> block, LIR lir, LIRGeneratorTool lirGen) {
        if (block.getPredecessorCount() > 1) {
            for (AbstractBlockBase<?> pred : block.getPredecessors()) {

                List<LIRInstruction> instructions = lir.getLIRforBlock(pred);

                int insertBefore = SSAUtils.phiOutIndex(lir, pred);

                PhiResolver resolver = PhiResolver.create(lirGen, new LIRInsertionBuffer(), instructions, insertBefore);
                SSAUtils.forEachPhiValuePair(lir, block, pred, resolver::move);
                resolver.dispose();

                SSAUtils.removePhiOut(lir, pred);
            }
            SSAUtils.removePhiIn(lir, block);
        }
    }

}