/*
 * Copyright (c) 2012, 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.hotspot.stubs;

import static com.oracle.graal.hotspot.nodes.DirectCompareAndSwapNode.*;
import static com.oracle.graal.hotspot.replacements.HotSpotReplacementsUtil.*;
import static com.oracle.graal.hotspot.stubs.StubUtil.*;
import static com.oracle.graal.nodes.extended.BranchProbabilityNode.*;

import com.oracle.graal.api.code.*;
import com.oracle.graal.api.meta.*;
import com.oracle.graal.api.replacements.*;
import com.oracle.graal.graph.Node.ConstantNodeParameter;
import com.oracle.graal.graph.Node.NodeIntrinsic;
import com.oracle.graal.hotspot.*;
import com.oracle.graal.hotspot.jvmci.*;
import com.oracle.graal.hotspot.meta.*;
import com.oracle.graal.hotspot.nodes.*;
import com.oracle.graal.hotspot.nodes.type.*;
import com.oracle.graal.hotspot.replacements.*;
import com.oracle.graal.hotspot.word.*;
import com.oracle.graal.nodes.*;
import com.oracle.graal.replacements.*;
import com.oracle.graal.replacements.Snippet.ConstantParameter;
import com.oracle.graal.word.*;

/**
 * Stub implementing the fast path for TLAB refill during instance class allocation. This stub is
 * called from the {@linkplain NewObjectSnippets inline} allocation code when TLAB allocation fails.
 * If this stub fails to refill the TLAB or allocate the object, it calls out to the HotSpot C++
 * runtime for to complete the allocation.
 */
public class NewInstanceStub extends SnippetStub {

    public NewInstanceStub(HotSpotProviders providers, HotSpotForeignCallLinkage linkage) {
        super("newInstance", providers, linkage);
    }

    @Override
    protected Object[] makeConstArgs() {
        HotSpotResolvedObjectType intArrayType = (HotSpotResolvedObjectType) providers.getMetaAccess().lookupJavaType(int[].class);
        int count = method.getSignature().getParameterCount(false);
        Object[] args = new Object[count];
        assert checkConstArg(1, "intArrayHub");
        assert checkConstArg(2, "threadRegister");
        args[1] = ConstantNode.forConstant(KlassPointerStamp.klassNonNull(), intArrayType.klass(), null);
        args[2] = providers.getRegisters().getThreadRegister();
        return args;
    }

    private static Word allocate(Word thread, int size) {
        Word top = readTlabTop(thread);
        Word end = readTlabEnd(thread);
        Word newTop = top.add(size);
        /*
         * this check might lead to problems if the TLAB is within 16GB of the address space end
         * (checked in c++ code)
         */
        if (probability(FAST_PATH_PROBABILITY, newTop.belowOrEqual(end))) {
            writeTlabTop(thread, newTop);
            return top;
        }
        return Word.zero();
    }

    @Fold
    private static boolean logging() {
        return Boolean.getBoolean("graal.logNewInstanceStub");
    }

    /**
     * Re-attempts allocation after an initial TLAB allocation failed or was skipped (e.g., due to
     * -XX:-UseTLAB).
     *
     * @param hub the hub of the object to be allocated
     * @param intArrayHub the hub for {@code int[].class}
     */
    @Snippet
    private static Object newInstance(KlassPointer hub, @ConstantParameter KlassPointer intArrayHub, @ConstantParameter Register threadRegister) {
        /*
         * The type is known to be an instance so Klass::_layout_helper is the instance size as a
         * raw number
         */
        int sizeInBytes = loadKlassLayoutHelperIntrinsic(hub);
        Word thread = registerAsWord(threadRegister);
        if (!forceSlowPath() && inlineContiguousAllocationSupported()) {
            if (isInstanceKlassFullyInitialized(hub)) {
                Word memory = refillAllocate(thread, intArrayHub, sizeInBytes, logging());
                if (memory.notEqual(0)) {
                    Word prototypeMarkWord = hub.readWord(prototypeMarkWordOffset(), PROTOTYPE_MARK_WORD_LOCATION);
                    NewObjectSnippets.formatObjectForStub(hub, sizeInBytes, memory, prototypeMarkWord);
                    return verifyObject(memory.toObject());
                }
            }
        }

        if (logging()) {
            printf("newInstance: calling new_instance_c\n");
        }

        newInstanceC(NEW_INSTANCE_C, thread, hub);
        handlePendingException(thread, true);
        return verifyObject(getAndClearObjectResult(thread));
    }

    /**
     * Attempts to refill the current thread's TLAB and retries the allocation.
     *
     * @param intArrayHub the hub for {@code int[].class}
     * @param sizeInBytes the size of the allocation
     * @param log specifies if logging is enabled
     *
     * @return the newly allocated, uninitialized chunk of memory, or {@link Word#zero()} if the
     *         operation was unsuccessful
     */
    static Word refillAllocate(Word thread, KlassPointer intArrayHub, int sizeInBytes, boolean log) {
        // If G1 is enabled, the "eden" allocation space is not the same always
        // and therefore we have to go to slowpath to allocate a new TLAB.
        if (useG1GC()) {
            return Word.zero();
        }
        if (!useTLAB()) {
            return edenAllocate(Word.unsigned(sizeInBytes), log);
        }
        Word intArrayMarkWord = Word.unsigned(tlabIntArrayMarkWord());
        int alignmentReserveInBytes = tlabAlignmentReserveInHeapWords() * wordSize();

        Word top = readTlabTop(thread);
        Word end = readTlabEnd(thread);

        // calculate amount of free space
        long tlabFreeSpaceInBytes = end.subtract(top).rawValue();

        if (log) {
            printf("refillTLAB: thread=%p\n", thread.rawValue());
            printf("refillTLAB: top=%p\n", top.rawValue());
            printf("refillTLAB: end=%p\n", end.rawValue());
            printf("refillTLAB: tlabFreeSpaceInBytes=%ld\n", tlabFreeSpaceInBytes);
        }

        long tlabFreeSpaceInWords = tlabFreeSpaceInBytes >>> log2WordSize();

        // Retain TLAB and allocate object in shared space if
        // the amount free in the TLAB is too large to discard.
        Word refillWasteLimit = thread.readWord(tlabRefillWasteLimitOffset(), TLAB_REFILL_WASTE_LIMIT_LOCATION);
        if (tlabFreeSpaceInWords <= refillWasteLimit.rawValue()) {
            if (tlabStats()) {
                // increment number of refills
                thread.writeInt(tlabNumberOfRefillsOffset(), thread.readInt(tlabNumberOfRefillsOffset(), TLAB_NOF_REFILLS_LOCATION) + 1, TLAB_NOF_REFILLS_LOCATION);
                if (log) {
                    printf("thread: %p -- number_of_refills %d\n", thread.rawValue(), thread.readInt(tlabNumberOfRefillsOffset(), TLAB_NOF_REFILLS_LOCATION));
                }
                // accumulate wastage
                int wastage = thread.readInt(tlabFastRefillWasteOffset(), TLAB_FAST_REFILL_WASTE_LOCATION) + (int) tlabFreeSpaceInWords;
                if (log) {
                    printf("thread: %p -- accumulated wastage %d\n", thread.rawValue(), wastage);
                }
                thread.writeInt(tlabFastRefillWasteOffset(), wastage, TLAB_FAST_REFILL_WASTE_LOCATION);
            }

            // if TLAB is currently allocated (top or end != null) then
            // fill [top, end + alignment_reserve) with array object
            if (top.notEqual(0)) {
                int headerSize = arrayBaseOffset(Kind.Int);
                // just like the HotSpot assembler stubs, assumes that tlabFreeSpaceInInts fits in
                // an int
                int tlabFreeSpaceInInts = (int) tlabFreeSpaceInBytes >>> 2;
                int length = ((alignmentReserveInBytes - headerSize) >>> 2) + tlabFreeSpaceInInts;
                NewObjectSnippets.formatArray(intArrayHub, -1, length, headerSize, top, intArrayMarkWord, false, false, false);

                long allocated = thread.readLong(threadAllocatedBytesOffset(), TLAB_THREAD_ALLOCATED_BYTES_LOCATION);
                allocated = allocated + top.subtract(readTlabStart(thread)).rawValue();
                thread.writeLong(threadAllocatedBytesOffset(), allocated, TLAB_THREAD_ALLOCATED_BYTES_LOCATION);
            }

            // refill the TLAB with an eden allocation
            Word tlabRefillSizeInWords = thread.readWord(threadTlabSizeOffset(), TLAB_SIZE_LOCATION);
            Word tlabRefillSizeInBytes = tlabRefillSizeInWords.multiply(wordSize());
            // allocate new TLAB, address returned in top
            top = edenAllocate(tlabRefillSizeInBytes, log);
            if (top.notEqual(0)) {
                end = top.add(tlabRefillSizeInBytes.subtract(alignmentReserveInBytes));
                initializeTlab(thread, top, end);

                return NewInstanceStub.allocate(thread, sizeInBytes);
            } else {
                return Word.zero();
            }
        } else {
            // Retain TLAB
            Word newRefillWasteLimit = refillWasteLimit.add(tlabRefillWasteIncrement());
            thread.writeWord(tlabRefillWasteLimitOffset(), newRefillWasteLimit, TLAB_REFILL_WASTE_LIMIT_LOCATION);
            if (log) {
                printf("refillTLAB: retaining TLAB - newRefillWasteLimit=%p\n", newRefillWasteLimit.rawValue());
            }

            if (tlabStats()) {
                thread.writeInt(tlabSlowAllocationsOffset(), thread.readInt(tlabSlowAllocationsOffset(), TLAB_SLOW_ALLOCATIONS_LOCATION) + 1, TLAB_SLOW_ALLOCATIONS_LOCATION);
            }

            return edenAllocate(Word.unsigned(sizeInBytes), log);
        }
    }

    /**
     * Attempts to allocate a chunk of memory from Eden space.
     *
     * @param sizeInBytes the size of the chunk to allocate
     * @param log specifies if logging is enabled
     * @return the allocated chunk or {@link Word#zero()} if allocation fails
     */
    public static Word edenAllocate(Word sizeInBytes, boolean log) {
        Word heapTopAddress = Word.unsigned(heapTopAddress());
        Word heapEndAddress = Word.unsigned(heapEndAddress());

        while (true) {
            Word heapTop = heapTopAddress.readWord(0, HEAP_TOP_LOCATION);
            Word newHeapTop = heapTop.add(sizeInBytes);
            if (newHeapTop.belowOrEqual(heapTop)) {
                return Word.zero();
            }

            Word heapEnd = heapEndAddress.readWord(0, HEAP_END_LOCATION);
            if (newHeapTop.aboveThan(heapEnd)) {
                return Word.zero();
            }

            if (compareAndSwap(heapTopAddress, 0, heapTop, newHeapTop, HEAP_TOP_LOCATION).equal(heapTop)) {
                return heapTop;
            }
        }
    }

    @Fold
    private static boolean forceSlowPath() {
        return Boolean.getBoolean("graal.newInstanceStub.forceSlowPath");
    }

    public static final ForeignCallDescriptor NEW_INSTANCE_C = newDescriptor(NewInstanceStub.class, "newInstanceC", void.class, Word.class, KlassPointer.class);

    @NodeIntrinsic(StubForeignCallNode.class)
    public static native void newInstanceC(@ConstantNodeParameter ForeignCallDescriptor newInstanceC, Word thread, KlassPointer hub);
}