/*
 * Copyright (c) 2016, 2020, Oracle and/or its affiliates.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 * conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided
 * with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.oracle.truffle.llvm.runtime.nodes.vars;

import java.nio.ByteOrder;

import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.CachedContext;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.memory.ByteArraySupport;
import com.oracle.truffle.api.nodes.ExplodeLoop;
import com.oracle.truffle.llvm.runtime.LLVMContext;
import com.oracle.truffle.llvm.runtime.LLVMLanguage;
import com.oracle.truffle.llvm.runtime.global.LLVMGlobal;
import com.oracle.truffle.llvm.runtime.nodes.api.LLVMStatementNode;
import com.oracle.truffle.llvm.runtime.nodes.memory.store.LLVMI64StoreNode.LLVMI64OffsetStoreNode;
import com.oracle.truffle.llvm.runtime.nodes.memory.store.LLVMI8StoreNode.LLVMI8OffsetStoreNode;
import com.oracle.truffle.llvm.runtime.nodes.memory.store.LLVMOffsetStoreNode;
import com.oracle.truffle.llvm.runtime.pointer.LLVMPointer;

public abstract class AggregateLiteralInPlaceNode extends LLVMStatementNode {

    @Children private final LLVMOffsetStoreNode[] stores;

    @CompilationFinal(dimensions = 1) private final byte[] data;
    @CompilationFinal(dimensions = 1) private final int[] offsets;
    @CompilationFinal(dimensions = 1) private final int[] sizes;
    @CompilationFinal(dimensions = 1) private final int[] bufferOffsets;
    @CompilationFinal(dimensions = 1) private final LLVMGlobal[] descriptors;

    private static final ByteArraySupport byteSupport = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN ? ByteArraySupport.bigEndian() : ByteArraySupport.littleEndian();

    
This node initializes a block of memory with a with combination of raw bytes and explicit store nodes. When executed, it transfers all bytes from data to the target (using i8 and i64 stores as appropriate), except for those covered by a node in stores. Every store node has a corresponding entry in offsets and {@sizes}. /**
     * This node initializes a block of memory with a with combination of raw bytes and explicit
     * store nodes. When executed, it transfers all bytes from {@code data} to the target (using i8
     * and i64 stores as appropriate), except for those covered by a node in {@code stores}. Every
     * store node has a corresponding entry in {@code offsets} and {@sizes}.
     */
    public AggregateLiteralInPlaceNode(byte[] data, LLVMOffsetStoreNode[] stores, int[] offsets, int[] sizes, int[] bufferOffsets, LLVMGlobal[] descriptors) {
        assert offsets.length == stores.length + 1 && stores.length == sizes.length;
        assert offsets[offsets.length - 1] == data.length : "offsets is expected to have a trailing entry with the overall size";
        assert bufferOffsets.length == descriptors.length;
        this.data = data;
        this.stores = stores;
        this.sizes = sizes;
        this.offsets = offsets;
        this.bufferOffsets = bufferOffsets;
        this.descriptors = descriptors;
    }

    @Specialization
    protected void initialize(VirtualFrame frame,
                    @CachedContext(LLVMLanguage.class) LLVMContext context,
                    @Cached LLVMI8OffsetStoreNode storeI8,
                    @Cached LLVMI64OffsetStoreNode storeI64) {
        writePrimitives(context, storeI8, storeI64);
        writeObjects(frame, context);
    }

    private void writePrimitives(LLVMContext context, LLVMI8OffsetStoreNode storeI8, LLVMI64OffsetStoreNode storeI64) {
        int offset = 0;
        int nextStore = 0;
        for (int i = 0; i < descriptors.length; i++) {
            LLVMPointer address = context.getSymbol(descriptors[i]);
            int bufferOffset = bufferOffsets[i];
            int bufferEnd = i == descriptors.length - 1 ? data.length : bufferOffsets[i + 1];
            while (offset < bufferEnd) {
                int nextStoreOffset = Math.min(offsets[nextStore], bufferEnd);
                offset = initializePrimitiveBlock(address, storeI8, storeI64, offset, nextStoreOffset, bufferOffset);
                if (offset < bufferEnd && nextStore < stores.length) {
                    offset += sizes[nextStore++];
                }
            }
        }
    }

    @ExplodeLoop
    private void writeObjects(VirtualFrame frame, LLVMContext context) {
        int offset = 0;
        int nextStore = 0;
        for (int i = 0; i < descriptors.length; i++) {
            LLVMPointer address = context.getSymbol(descriptors[i]);
            int bufferOffset = bufferOffsets[i];
            int bufferEnd = i == descriptors.length - 1 ? data.length : bufferOffsets[i + 1];
            while (offset < bufferEnd) {
                offset = Math.min(offsets[nextStore], bufferEnd);
                if (offset < bufferEnd && nextStore < stores.length) {
                    stores[nextStore].executeWithTarget(frame, address, offset - bufferOffset);
                    offset += sizes[nextStore++];
                }
            }
        }
    }

    private int initializePrimitiveBlock(LLVMPointer address, LLVMI8OffsetStoreNode storeI8, LLVMI64OffsetStoreNode storeI64, int startOffset, int nextStoreOffset, int bufferOffset) {
        int offset = startOffset;
        // This loop ensures that the target offset is aligned for the 64-bit write loop below.
        // (the source offset might not be aligned)
        while (offset < nextStoreOffset && (((offset - bufferOffset) & 0x7) != 0)) {
            storeI8.executeWithTarget(address, offset - bufferOffset, data[offset]);
            offset++;
        }
        while (offset < (nextStoreOffset - 7)) {
            storeI64.executeWithTarget(address, offset - bufferOffset, byteSupport.getLong(data, offset));
            offset += Long.BYTES;
        }
        while (offset < nextStoreOffset) {
            storeI8.executeWithTarget(address, offset - bufferOffset, data[offset]);
            offset++;
        }
        return offset;
    }
}