/*
 * Copyright (c) 2014, 2014, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.graal.lir;

import java.util.*;

import com.oracle.graal.api.code.*;
import com.oracle.graal.api.meta.*;
import com.oracle.graal.asm.*;
import com.oracle.graal.lir.gen.*;

/**
 * A simple forwarder to {@link FrameMap}.
 */
public class ForwardingFrameMapBuilder implements FrameMapBuilder {

    @FunctionalInterface
    public interface FrameMapFactory {
        FrameMap newFrameMap(FrameMapBuilder frameMapBuilder);
    }

    private final FrameMap frameMap;
    private final RegisterConfig registerConfig;
    private final CodeCacheProvider codeCache;

    public ForwardingFrameMapBuilder(FrameMapFactory factory, CodeCacheProvider codeCache, RegisterConfig registerConfig) {
        this.registerConfig = registerConfig == null ? codeCache.getRegisterConfig() : registerConfig;
        this.codeCache = codeCache;
        // all members must be set up before calling FrameMapFactory#newFrameMap
        this.frameMap = factory.newFrameMap(this);
    }

    private Set<VirtualStackSlot> freedSlots;

    public VirtualStackSlot allocateSpillSlot(LIRKind kind) {
        if (freedSlots != null) {
            for (Iterator<VirtualStackSlot> iter = freedSlots.iterator(); iter.hasNext();) {
                VirtualStackSlot s = iter.next();
                if (s.getLIRKind().equals(kind)) {
                    iter.remove();
                    if (freedSlots.isEmpty()) {
                        freedSlots = null;
                    }
                    return s;
                }
            }
        }
        int size = frameMap.spillSlotSize(kind);
        frameMap.spillSize = NumUtil.roundUp(frameMap.spillSize + size, size);
        return frameMap.allocateNewSpillSlot(kind, 0);
    }

    public StackSlot allocateStackSlots(int slots, BitSet objects, List<StackSlot> outObjectStackSlots) {
        if (slots == 0) {
            return null;
        }
        frameMap.spillSize += (slots * frameMap.getTarget().wordSize);

        if (!objects.isEmpty()) {
            assert objects.length() <= slots;
            StackSlot result = null;
            for (int slotIndex = 0; slotIndex < slots; slotIndex++) {
                StackSlot objectSlot = null;
                if (objects.get(slotIndex)) {
                    objectSlot = frameMap.allocateNewSpillSlot(LIRKind.reference(Kind.Object), slotIndex * frameMap.getTarget().wordSize);
                    frameMap.addObjectStackSlot(objectSlot);
                    if (outObjectStackSlots != null) {
                        outObjectStackSlots.add(objectSlot);
                    }
                }
                if (slotIndex == 0) {
                    if (objectSlot != null) {
                        result = objectSlot;
                    } else {
                        result = frameMap.allocateNewSpillSlot(LIRKind.value(frameMap.getTarget().wordKind), 0);
                    }
                }
            }
            assert result != null;
            return result;

        } else {
            return frameMap.allocateNewSpillSlot(LIRKind.value(frameMap.getTarget().wordKind), 0);
        }
    }

    public RegisterConfig getRegisterConfig() {
        return registerConfig;
    }

    public CodeCacheProvider getCodeCache() {
        return codeCache;
    }

    public void freeSpillSlot(VirtualStackSlot slot) {
        if (freedSlots == null) {
            freedSlots = new HashSet<>();
        }
        freedSlots.add(slot);
    }

    public void callsMethod(CallingConvention cc) {
        frameMap.callsMethod(cc);
    }

    public FrameMap buildFrameMap(LIRGenerationResult res) {
        if (freedSlots != null) {
            // If the freed slots cover the complete spill area (except for the return
            // address slot), then the spill size is reset to its initial value.
            // Without this, frameNeedsAllocating() would never return true.
            int total = 0;
            for (VirtualStackSlot s : freedSlots) {
                total += frameMap.getTarget().getSizeInBytes(s.getKind());
            }
            if (total == frameMap.spillSize - frameMap.initialSpillSize) {
                // reset spill area size
                frameMap.spillSize = frameMap.initialSpillSize;
            }
            freedSlots = null;
        }
        frameMap.finish();
        return frameMap;
    }

}