/*

 * Copyright (c) 2013, 2017, 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

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package org.graalvm.compiler.lir.sparc;

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

import static jdk.vm.ci.sparc.SPARC.g0;

import static jdk.vm.ci.sparc.SPARCKind.WORD;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.BPCC;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.Annul.ANNUL;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.Annul.NOT_ANNUL;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.BranchPredict.PREDICT_NOT_TAKEN;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.BranchPredict.PREDICT_TAKEN;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.CC.Xcc;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.ConditionFlag.Equal;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.ConditionFlag.Less;

import static org.graalvm.compiler.asm.sparc.SPARCAssembler.ConditionFlag.NotEqual;

import static org.graalvm.compiler.lir.LIRInstruction.OperandFlag.REG;

import org.graalvm.compiler.asm.Label;

import org.graalvm.compiler.asm.sparc.SPARCAddress;

import org.graalvm.compiler.asm.sparc.SPARCMacroAssembler;

import org.graalvm.compiler.core.common.LIRKind;

import org.graalvm.compiler.lir.LIRInstructionClass;

import org.graalvm.compiler.lir.Opcode;

import org.graalvm.compiler.lir.asm.CompilationResultBuilder;

import org.graalvm.compiler.lir.gen.LIRGeneratorTool;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.meta.AllocatableValue;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.sparc.SPARCKind;

/**

 * Emits code which compares two arrays of the same length.

 */

@Opcode("ARRAY_EQUALS")

public final class SPARCArrayEqualsOp extends SPARCLIRInstruction {

    public static final LIRInstructionClass<SPARCArrayEqualsOp> TYPE = LIRInstructionClass.create(SPARCArrayEqualsOp.class);

    public static final SizeEstimate SIZE = SizeEstimate.create(32);

    private final JavaKind kind;

    private final int arrayBaseOffset;

    private final int arrayIndexScale;

    @Def({REG}) protected AllocatableValue resultValue;

    @Alive({REG}) protected AllocatableValue array1Value;

    @Alive({REG}) protected AllocatableValue array2Value;

    @Alive({REG}) protected AllocatableValue lengthValue;

    @Temp({REG}) protected AllocatableValue temp1;

    @Temp({REG}) protected AllocatableValue temp2;

    @Temp({REG}) protected AllocatableValue temp3;

    @Temp({REG}) protected AllocatableValue temp4;

    @Temp({REG}) protected AllocatableValue temp5;

    public SPARCArrayEqualsOp(LIRGeneratorTool tool, JavaKind kind, AllocatableValue result, AllocatableValue array1, AllocatableValue array2, AllocatableValue length) {

        super(TYPE, SIZE);

        assert !kind.isNumericFloat() : "Float arrays comparison (bitwise_equal || both_NaN) isn't supported";

        this.kind = kind;

        this.resultValue = result;

        this.array1Value = array1;

        this.array2Value = array2;

        this.lengthValue = length;

        // Allocate some temporaries.

        this.temp1 = tool.newVariable(LIRKind.unknownReference(tool.target().arch.getWordKind()));

        this.temp2 = tool.newVariable(LIRKind.unknownReference(tool.target().arch.getWordKind()));

        this.temp3 = tool.newVariable(LIRKind.value(tool.target().arch.getWordKind()));

        this.temp4 = tool.newVariable(LIRKind.value(tool.target().arch.getWordKind()));

        this.temp5 = tool.newVariable(LIRKind.value(tool.target().arch.getWordKind()));

    }

    @Override

    public void emitCode(CompilationResultBuilder crb, SPARCMacroAssembler masm) {

        Register result = asRegister(resultValue);

        Register array1 = asRegister(temp1);

        Register array2 = asRegister(temp2);

        Register length = asRegister(temp3);

        Label trueLabel = new Label();

        Label falseLabel = new Label();

        Label done = new Label();

        // Load array base addresses.

        masm.add(asRegister(array1Value), arrayBaseOffset, array1);

        masm.add(asRegister(array2Value), arrayBaseOffset, array2);

        // Get array length in bytes.

        masm.mulx(asRegister(lengthValue, WORD), arrayIndexScale, length);

        masm.mov(length, result); // copy

        emit8ByteCompare(masm, result, array1, array2, length, trueLabel, falseLabel);

        emitTailCompares(masm, result, array1, array2, trueLabel, falseLabel);

        // Return true

        masm.bind(trueLabel);

        masm.mov(1, result);

        masm.jmp(done);

        // Return false

        masm.bind(falseLabel);

        masm.mov(g0, result);

        // That's it

        masm.bind(done);

    }

    /**

     * Vector size used in {@link #emit8ByteCompare}.

     */

    private static final int VECTOR_SIZE = 8;

    /**

     * Emits code that uses 8-byte vector compares.

     */

    private void emit8ByteCompare(SPARCMacroAssembler masm, Register result, Register array1, Register array2, Register length, Label trueLabel, Label falseLabel) {

        assert lengthValue.getPlatformKind().equals(SPARCKind.WORD);

        Label loop = new Label();

        Label compareTail = new Label();

        Label compareTailCorrectVectorEnd = new Label();

        Register tempReg1 = asRegister(temp4);

        Register tempReg2 = asRegister(temp5);

        masm.sra(length, 0, length);

        masm.and(result, VECTOR_SIZE - 1, result); // tail count (in bytes)

        masm.andcc(length, ~(VECTOR_SIZE - 1), length);  // vector count (in bytes)

        BPCC.emit(masm, Xcc, Equal, NOT_ANNUL, PREDICT_NOT_TAKEN, compareTail);

        masm.sub(length, VECTOR_SIZE, length); // Delay slot

        masm.add(array1, length, array1);

        masm.add(array2, length, array2);

        masm.sub(g0, length, length);

        // Compare the last element first

        masm.ldx(new SPARCAddress(array1, 0), tempReg1);

        masm.ldx(new SPARCAddress(array2, 0), tempReg2);

        masm.compareBranch(tempReg1, tempReg2, NotEqual, Xcc, falseLabel, PREDICT_NOT_TAKEN, null);

        masm.compareBranch(length, 0, Equal, Xcc, compareTailCorrectVectorEnd, PREDICT_NOT_TAKEN, null);

        // Load the first value from array 1 (Later done in back branch delay-slot)

        masm.ldx(new SPARCAddress(array1, length), tempReg1);

        masm.bind(loop);

        masm.ldx(new SPARCAddress(array2, length), tempReg2);

        masm.cmp(tempReg1, tempReg2);

        BPCC.emit(masm, Xcc, NotEqual, NOT_ANNUL, PREDICT_NOT_TAKEN, falseLabel);

        // Delay slot, not annul, add for next iteration

        masm.addcc(length, VECTOR_SIZE, length);

        // Annul, to prevent access past the array

        BPCC.emit(masm, Xcc, NotEqual, ANNUL, PREDICT_TAKEN, loop);

        masm.ldx(new SPARCAddress(array1, length), tempReg1); // Load in delay slot

        // Tail count zero, therefore we can go to the end

        masm.compareBranch(result, 0, Equal, Xcc, trueLabel, PREDICT_TAKEN, null);

        masm.bind(compareTailCorrectVectorEnd);

        // Correct the array pointers

        masm.add(array1, VECTOR_SIZE, array1);

        masm.add(array2, VECTOR_SIZE, array2);

        masm.bind(compareTail);

    }

    /**

     * Emits code to compare the remaining 1 to 4 bytes.

     */

    private void emitTailCompares(SPARCMacroAssembler masm, Register result, Register array1, Register array2, Label trueLabel, Label falseLabel) {

        Label compare2Bytes = new Label();

        Label compare1Byte = new Label();

        Register tempReg1 = asRegister(temp3);

        Register tempReg2 = asRegister(temp4);

        if (kind.getByteCount() <= 4) {

            // Compare trailing 4 bytes, if any.

            masm.compareBranch(result, 4, Less, Xcc, compare2Bytes, PREDICT_NOT_TAKEN, null);

            masm.lduw(new SPARCAddress(array1, 0), tempReg1);

            masm.lduw(new SPARCAddress(array2, 0), tempReg2);

            masm.compareBranch(tempReg1, tempReg2, NotEqual, Xcc, falseLabel, PREDICT_NOT_TAKEN, null);

            if (kind.getByteCount() <= 2) {

                // Move array pointers forward.

                masm.add(array1, 4, array1);

                masm.add(array2, 4, array2);

                masm.sub(result, 4, result);

                // Compare trailing 2 bytes, if any.

                masm.bind(compare2Bytes);

                masm.compareBranch(result, 2, Less, Xcc, compare1Byte, PREDICT_TAKEN, null);

                masm.lduh(new SPARCAddress(array1, 0), tempReg1);

                masm.lduh(new SPARCAddress(array2, 0), tempReg2);

                masm.compareBranch(tempReg1, tempReg2, NotEqual, Xcc, falseLabel, PREDICT_TAKEN, null);

                // The one-byte tail compare is only required for boolean and byte arrays.

                if (kind.getByteCount() <= 1) {

                    // Move array pointers forward before we compare the last trailing byte.

                    masm.add(array1, 2, array1);

                    masm.add(array2, 2, array2);

                    masm.sub(result, 2, result);

                    // Compare trailing byte, if any.

                    masm.bind(compare1Byte);

                    masm.compareBranch(result, 1, NotEqual, Xcc, trueLabel, PREDICT_TAKEN, null);

                    masm.ldub(new SPARCAddress(array1, 0), tempReg1);

                    masm.ldub(new SPARCAddress(array2, 0), tempReg2);

                    masm.compareBranch(tempReg1, tempReg2, NotEqual, Xcc, falseLabel, PREDICT_TAKEN, null);

                } else {

                    masm.bind(compare1Byte);

                }

            } else {

                masm.bind(compare2Bytes);

            }

        }

    }

}