/*
 * Copyright (c) 2014, 2019, 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.lir.dfa;

import static jdk.vm.ci.code.ValueUtil.asRegister;
import static jdk.vm.ci.code.ValueUtil.isRegister;
import static jdk.vm.ci.code.ValueUtil.isStackSlot;

import org.graalvm.compiler.core.common.LIRKind;
import org.graalvm.compiler.lir.LIR;
import org.graalvm.compiler.lir.LIRFrameState;
import org.graalvm.compiler.lir.LIRInstruction;
import org.graalvm.compiler.lir.framemap.FrameMap;
import org.graalvm.compiler.lir.framemap.ReferenceMapBuilder;
import org.graalvm.compiler.lir.gen.LIRGenerationResult;
import org.graalvm.compiler.lir.phases.AllocationPhase;

import jdk.vm.ci.code.ReferenceMap;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.RegisterAttributes;
import jdk.vm.ci.code.TargetDescription;
import jdk.vm.ci.meta.Value;

/**
 * Mark all live references for a frame state. The frame state uses this information to build the
 * {@link ReferenceMap}s.
 */
public final class LocationMarkerPhase extends AllocationPhase {

    @Override
    protected void run(TargetDescription target, LIRGenerationResult lirGenRes, AllocationContext context) {
        new Marker(lirGenRes.getLIR(), lirGenRes.getFrameMap()).build();
    }

    static final class Marker extends LocationMarker<RegStackValueSet> {

        private final RegisterAttributes[] registerAttributes;

        private Marker(LIR lir, FrameMap frameMap) {
            super(lir, frameMap);
            this.registerAttributes = frameMap.getRegisterConfig().getAttributesMap();
        }

        @Override
        protected RegStackValueSet newLiveValueSet() {
            return new RegStackValueSet(frameMap);
        }

        @Override
        protected boolean shouldProcessValue(Value operand) {
            if (isRegister(operand)) {
                Register reg = asRegister(operand);
                if (!reg.mayContainReference() || !attributes(reg).isAllocatable()) {
                    // register that's not allocatable or not part of the reference map
                    return false;
                }
            } else if (!isStackSlot(operand)) {
                // neither register nor stack slot
                return false;
            }

            return !operand.getValueKind().equals(LIRKind.Illegal);
        }

        /**
         * This method does the actual marking.
         */
        @Override
        protected void processState(LIRInstruction op, LIRFrameState info, RegStackValueSet values) {
            if (!info.hasDebugInfo()) {
                info.initDebugInfo(frameMap, !op.destroysCallerSavedRegisters() || !frameMap.getRegisterConfig().areAllAllocatableRegistersCallerSaved());
            }

            ReferenceMapBuilder refMap = frameMap.newReferenceMapBuilder();
            values.addLiveValues(refMap);

            info.debugInfo().setReferenceMap(refMap.finish(info));
        }

        /**
         * Gets an object describing the attributes of a given register according to this register
         * configuration.
         */
        private RegisterAttributes attributes(Register reg) {
            return registerAttributes[reg.number];
        }

    }
}