/*

 * Copyright (c) 2013, 2016, 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 org.graalvm.compiler.core.aarch64;

import static org.graalvm.compiler.lir.LIRValueUtil.asJavaConstant;

import static org.graalvm.compiler.lir.LIRValueUtil.isJavaConstant;

import java.util.function.Function;

import org.graalvm.compiler.asm.aarch64.AArch64Address.AddressingMode;

import org.graalvm.compiler.asm.aarch64.AArch64Assembler.ConditionFlag;

import org.graalvm.compiler.asm.aarch64.AArch64MacroAssembler;

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

import org.graalvm.compiler.core.common.calc.Condition;

import org.graalvm.compiler.core.common.spi.LIRKindTool;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.lir.LIRFrameState;

import org.graalvm.compiler.lir.LIRValueUtil;

import org.graalvm.compiler.lir.LabelRef;

import org.graalvm.compiler.lir.StandardOp;

import org.graalvm.compiler.lir.SwitchStrategy;

import org.graalvm.compiler.lir.Variable;

import org.graalvm.compiler.lir.aarch64.AArch64AddressValue;

import org.graalvm.compiler.lir.aarch64.AArch64ArithmeticOp;

import org.graalvm.compiler.lir.aarch64.AArch64Compare;

import org.graalvm.compiler.lir.aarch64.AArch64ControlFlow;

import org.graalvm.compiler.lir.aarch64.AArch64ControlFlow.BranchOp;

import org.graalvm.compiler.lir.aarch64.AArch64ControlFlow.CondMoveOp;

import org.graalvm.compiler.lir.aarch64.AArch64ControlFlow.StrategySwitchOp;

import org.graalvm.compiler.lir.aarch64.AArch64Move;

import org.graalvm.compiler.lir.aarch64.AArch64Move.CompareAndSwapOp;

import org.graalvm.compiler.lir.aarch64.AArch64Move.MembarOp;

import org.graalvm.compiler.lir.aarch64.AArch64PauseOp;

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

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

import org.graalvm.compiler.phases.util.Providers;

import jdk.vm.ci.aarch64.AArch64Kind;

import jdk.vm.ci.code.RegisterValue;

import jdk.vm.ci.meta.AllocatableValue;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.PlatformKind;

import jdk.vm.ci.meta.PrimitiveConstant;

import jdk.vm.ci.meta.Value;

import jdk.vm.ci.meta.ValueKind;

public abstract class AArch64LIRGenerator extends LIRGenerator {

    public AArch64LIRGenerator(LIRKindTool lirKindTool, AArch64ArithmeticLIRGenerator arithmeticLIRGen, MoveFactory moveFactory, Providers providers, LIRGenerationResult lirGenRes) {

        super(lirKindTool, arithmeticLIRGen, moveFactory, providers, lirGenRes);

    }

    /**

     * Checks whether the supplied constant can be used without loading it into a register for store

     * operations, i.e., on the right hand side of a memory access.

     *

     * @param c The constant to check.

     * @return True if the constant can be used directly, false if the constant needs to be in a

     *         register.

     */

    protected static final boolean canStoreConstant(JavaConstant c) {

        // Our own code never calls this since we can't make a definite statement about whether or

        // not we can inline a constant without knowing what kind of operation we execute. Let's be

        // optimistic here and fix up mistakes later.

        return true;

    }

    /**

     * AArch64 cannot use anything smaller than a word in any instruction other than load and store.

     */

    @Override

    public <K extends ValueKind<K>> K toRegisterKind(K kind) {

        switch ((AArch64Kind) kind.getPlatformKind()) {

            case BYTE:

            case WORD:

                return kind.changeType(AArch64Kind.DWORD);

            default:

                return kind;

        }

    }

    @Override

    public void emitNullCheck(Value address, LIRFrameState state) {

        append(new AArch64Move.NullCheckOp(asAddressValue(address), state));

    }

    @Override

    public Variable emitAddress(AllocatableValue stackslot) {

        Variable result = newVariable(LIRKind.value(target().arch.getWordKind()));

        append(new AArch64Move.StackLoadAddressOp(result, stackslot));

        return result;

    }

    public AArch64AddressValue asAddressValue(Value address) {

        if (address instanceof AArch64AddressValue) {

            return (AArch64AddressValue) address;

        } else {

            return new AArch64AddressValue(address.getValueKind(), asAllocatable(address), Value.ILLEGAL, 0, false, AddressingMode.BASE_REGISTER_ONLY);

        }

    }

    @Override

    public Variable emitCompareAndSwap(Value address, Value expectedValue, Value newValue, Value trueValue, Value falseValue) {

        Variable result = newVariable(trueValue.getValueKind());

        Variable scratch = newVariable(LIRKind.value(AArch64Kind.WORD));

        append(new CompareAndSwapOp(result, loadNonCompareConst(expectedValue), loadReg(newValue), asAllocatable(address), scratch));

        return result;

    }

    @Override

    public void emitMembar(int barriers) {

        int necessaryBarriers = target().arch.requiredBarriers(barriers);

        if (target().isMP && necessaryBarriers != 0) {

            append(new MembarOp(necessaryBarriers));

        }

    }

    @Override

    public void emitJump(LabelRef label) {

        assert label != null;

        append(new StandardOp.JumpOp(label));

    }

    @Override

    public void emitOverflowCheckBranch(LabelRef overflow, LabelRef noOverflow, LIRKind cmpKind, double overflowProbability) {

        append(new AArch64ControlFlow.BranchOp(ConditionFlag.VS, overflow, noOverflow, overflowProbability));

    }

    /**

     * Branches to label if (left & right) == 0. If negated is true branchse on non-zero instead.

     *

     * @param left Integer kind. Non null.

     * @param right Integer kind. Non null.

     * @param trueDestination destination if left & right == 0. Non null.

     * @param falseDestination destination if left & right != 0. Non null

     * @param trueSuccessorProbability hoistoric probability that comparison is true

     */

    @Override

    public void emitIntegerTestBranch(Value left, Value right, LabelRef trueDestination, LabelRef falseDestination, double trueSuccessorProbability) {

        assert ((AArch64Kind) left.getPlatformKind()).isInteger() && left.getPlatformKind() == right.getPlatformKind();

        ((AArch64ArithmeticLIRGenerator) getArithmetic()).emitBinary(LIRKind.combine(left, right), AArch64ArithmeticOp.ANDS, true, left, right);

        append(new AArch64ControlFlow.BranchOp(ConditionFlag.EQ, trueDestination, falseDestination, trueSuccessorProbability));

    }

    /**

     * Conditionally move trueValue into new variable if cond + unorderedIsTrue is true, else

     * falseValue.

     *

     * @param left Arbitrary value. Has to have same type as right. Non null.

     * @param right Arbitrary value. Has to have same type as left. Non null.

     * @param cond condition that decides whether to move trueValue or falseValue into result. Non

     *            null.

     * @param unorderedIsTrue defines whether floating-point comparisons consider unordered true or

     *            not. Ignored for integer comparisons.

     * @param trueValue arbitrary value same type as falseValue. Non null.

     * @param falseValue arbitrary value same type as trueValue. Non null.

     * @return value containing trueValue if cond + unorderedIsTrue is true, else falseValue. Non

     *         null.

     */

    @Override

    public Variable emitConditionalMove(PlatformKind cmpKind, Value left, Value right, Condition cond, boolean unorderedIsTrue, Value trueValue, Value falseValue) {

        boolean mirrored = emitCompare(cmpKind, left, right, cond, unorderedIsTrue);

        Condition finalCondition = mirrored ? cond.mirror() : cond;

        boolean finalUnorderedIsTrue = mirrored ? !unorderedIsTrue : unorderedIsTrue;

        ConditionFlag cmpCondition = toConditionFlag(((AArch64Kind) cmpKind).isInteger(), finalCondition, finalUnorderedIsTrue);

        Variable result = newVariable(trueValue.getValueKind());

        append(new CondMoveOp(result, cmpCondition, loadReg(trueValue), loadReg(falseValue)));

        return result;

    }

    @Override

    public void emitCompareBranch(PlatformKind cmpKind, Value left, Value right, Condition cond, boolean unorderedIsTrue, LabelRef trueDestination, LabelRef falseDestination,

                    double trueDestinationProbability) {

        boolean mirrored = emitCompare(cmpKind, left, right, cond, unorderedIsTrue);

        Condition finalCondition = mirrored ? cond.mirror() : cond;

        boolean finalUnorderedIsTrue = mirrored ? !unorderedIsTrue : unorderedIsTrue;

        ConditionFlag cmpCondition = toConditionFlag(((AArch64Kind) cmpKind).isInteger(), finalCondition, finalUnorderedIsTrue);

        append(new BranchOp(cmpCondition, trueDestination, falseDestination, trueDestinationProbability));

    }

    private static ConditionFlag toConditionFlag(boolean isInt, Condition cond, boolean unorderedIsTrue) {

        return isInt ? toIntConditionFlag(cond) : toFloatConditionFlag(cond, unorderedIsTrue);

    }

    /**

     * Takes a Condition and unorderedIsTrue flag and returns the correct Aarch64 specific

     * ConditionFlag. Note: This is only correct if the emitCompare code for floats has correctly

     * handled the case of 'EQ && unorderedIsTrue', respectively 'NE && !unorderedIsTrue'!

     */

    private static ConditionFlag toFloatConditionFlag(Condition cond, boolean unorderedIsTrue) {

        switch (cond) {

            case LT:

                return unorderedIsTrue ? ConditionFlag.LT : ConditionFlag.LO;

            case LE:

                return unorderedIsTrue ? ConditionFlag.LE : ConditionFlag.LS;

            case GE:

                return unorderedIsTrue ? ConditionFlag.PL : ConditionFlag.GE;

            case GT:

                return unorderedIsTrue ? ConditionFlag.HI : ConditionFlag.GT;

            case EQ:

                return ConditionFlag.EQ;

            case NE:

                return ConditionFlag.NE;

            default:

                throw GraalError.shouldNotReachHere();

        }

    }

    /**

     * Takes a Condition and returns the correct Aarch64 specific ConditionFlag.

     */

    private static ConditionFlag toIntConditionFlag(Condition cond) {

        switch (cond) {

            case EQ:

                return ConditionFlag.EQ;

            case NE:

                return ConditionFlag.NE;

            case LT:

                return ConditionFlag.LT;

            case LE:

                return ConditionFlag.LE;

            case GT:

                return ConditionFlag.GT;

            case GE:

                return ConditionFlag.GE;

            case AE:

                return ConditionFlag.HS;

            case BE:

                return ConditionFlag.LS;

            case AT:

                return ConditionFlag.HI;

            case BT:

                return ConditionFlag.LO;

            default:

                throw GraalError.shouldNotReachHere();

        }

    }

    /**

     * This method emits the compare instruction, and may reorder the operands. It returns true if

     * it did so.

     *

     * @param a the left operand of the comparison. Has to have same type as b. Non null.

     * @param b the right operand of the comparison. Has to have same type as a. Non null.

     * @return true if mirrored (i.e. "b cmp a" instead of "a cmp b" was done).

     */

    protected boolean emitCompare(PlatformKind cmpKind, Value a, Value b, Condition condition, boolean unorderedIsTrue) {

        Value left;

        Value right;

        boolean mirrored;

        AArch64Kind kind = (AArch64Kind) cmpKind;

        if (kind.isInteger()) {

            if (LIRValueUtil.isVariable(b)) {

                left = load(b);

                right = loadNonConst(a);

                mirrored = true;

            } else {

                left = load(a);

                right = loadNonConst(b);

                mirrored = false;

            }

            append(new AArch64Compare.CompareOp(left, loadNonCompareConst(right)));

        } else if (kind.isSIMD()) {

            if (AArch64Compare.FloatCompareOp.isFloatCmpConstant(a, condition, unorderedIsTrue)) {

                left = load(b);

                right = a;

                mirrored = true;

            } else if (AArch64Compare.FloatCompareOp.isFloatCmpConstant(b, condition, unorderedIsTrue)) {

                left = load(a);

                right = b;

                mirrored = false;

            } else {

                left = load(a);

                right = loadReg(b);

                mirrored = false;

            }

            append(new AArch64Compare.FloatCompareOp(left, asAllocatable(right), condition, unorderedIsTrue));

        } else {

            throw GraalError.shouldNotReachHere();

        }

        return mirrored;

    }

    /**

     * If value is a constant that cannot be used directly with a gpCompare instruction load it into

     * a register and return the register, otherwise return constant value unchanged.

     */

    protected Value loadNonCompareConst(Value value) {

        if (!isCompareConstant(value)) {

            return loadReg(value);

        }

        return value;

    }

    /**

     * Checks whether value can be used directly with a gpCompare instruction. This is <b>not</b>

     * the same as {@link AArch64ArithmeticLIRGenerator#isArithmeticConstant(JavaConstant)}, because

     * 0.0 is a valid compare constant for floats, while there are no arithmetic constants for

     * floats.

     *

     * @param value any type. Non null.

     * @return true if value can be used directly in comparison instruction, false otherwise.

     */

    public boolean isCompareConstant(Value value) {

        if (isJavaConstant(value)) {

            JavaConstant constant = asJavaConstant(value);

            if (constant instanceof PrimitiveConstant) {

                final long longValue = constant.asLong();

                long maskedValue;

                switch (constant.getJavaKind()) {

                    case Boolean:

                    case Byte:

                        maskedValue = longValue & 0xFF;

                        break;

                    case Char:

                    case Short:

                        maskedValue = longValue & 0xFFFF;

                        break;

                    case Int:

                        maskedValue = longValue & 0xFFFF_FFFF;

                        break;

                    case Long:

                        maskedValue = longValue;

                        break;

                    default:

                        throw GraalError.shouldNotReachHere();

                }

                return AArch64MacroAssembler.isArithmeticImmediate(maskedValue);

            } else {

                return constant.isDefaultForKind();

            }

        }

        return false;

    }

    /**

     * Moves trueValue into result if (left & right) == 0, else falseValue.

     *

     * @param left Integer kind. Non null.

     * @param right Integer kind. Non null.

     * @param trueValue Integer kind. Non null.

     * @param falseValue Integer kind. Non null.

     * @return virtual register containing trueValue if (left & right) == 0, else falseValue.

     */

    @Override

    public Variable emitIntegerTestMove(Value left, Value right, Value trueValue, Value falseValue) {

        assert ((AArch64Kind) left.getPlatformKind()).isInteger() && ((AArch64Kind) right.getPlatformKind()).isInteger();

        assert ((AArch64Kind) trueValue.getPlatformKind()).isInteger() && ((AArch64Kind) falseValue.getPlatformKind()).isInteger();

        ((AArch64ArithmeticLIRGenerator) getArithmetic()).emitBinary(trueValue.getValueKind(), AArch64ArithmeticOp.ANDS, true, left, right);

        Variable result = newVariable(trueValue.getValueKind());

        append(new CondMoveOp(result, ConditionFlag.EQ, load(trueValue), load(falseValue)));

        return result;

    }

    @Override

    public void emitStrategySwitch(SwitchStrategy strategy, Variable key, LabelRef[] keyTargets, LabelRef defaultTarget) {

        append(createStrategySwitchOp(strategy, keyTargets, defaultTarget, key, newVariable(key.getValueKind()), AArch64LIRGenerator::toIntConditionFlag));

    }

    protected StrategySwitchOp createStrategySwitchOp(SwitchStrategy strategy, LabelRef[] keyTargets, LabelRef defaultTarget, Variable key, AllocatableValue scratchValue,

                    Function<Condition, ConditionFlag> converter) {

        return new StrategySwitchOp(strategy, keyTargets, defaultTarget, key, scratchValue, converter);

    }

    @Override

    protected void emitTableSwitch(int lowKey, LabelRef defaultTarget, LabelRef[] targets, Value key) {

        // Make copy of key since the TableSwitch destroys its input.

        Variable tmp = emitMove(key);

        Variable scratch = newVariable(LIRKind.value(AArch64Kind.WORD));

        append(new AArch64ControlFlow.TableSwitchOp(lowKey, defaultTarget, targets, tmp, scratch));

    }

    @Override

    public Variable emitByteSwap(Value operand) {

        // TODO (das) Do not generate until we support vector instructions

        throw GraalError.unimplemented("Do not generate until we support vector instructions");

    }

    @Override

    public Variable emitArrayEquals(JavaKind kind, Value array1, Value array2, Value length) {

        // TODO (das) Do not generate until we support vector instructions

        throw GraalError.unimplemented("Do not generate until we support vector instructions");

    }

    @Override

    protected JavaConstant zapValueForKind(PlatformKind kind) {

        long dead = 0xDEADDEADDEADDEADL;

        switch ((AArch64Kind) kind) {

            case BYTE:

                return JavaConstant.forByte((byte) dead);

            case WORD:

                return JavaConstant.forShort((short) dead);

            case DWORD:

                return JavaConstant.forInt((int) dead);

            case QWORD:

                return JavaConstant.forLong(dead);

            case SINGLE:

                return JavaConstant.forFloat(Float.intBitsToFloat((int) dead));

            case DOUBLE:

                return JavaConstant.forDouble(Double.longBitsToDouble(dead));

            default:

                throw GraalError.shouldNotReachHere();

        }

    }

    /**

     * Loads value into virtual register. Contrary to {@link #load(Value)} this handles

     * RegisterValues (i.e. values corresponding to fixed physical registers) correctly, by not

     * creating an unnecessary move into a virtual register.

     *

     * This avoids generating the following code: mov x0, x19 # x19 is fixed thread register ldr x0,

     * [x0] instead of: ldr x0, [x19].

     */

    protected AllocatableValue loadReg(Value val) {

        if (!(val instanceof Variable || val instanceof RegisterValue)) {

            return emitMove(val);

        }

        return (AllocatableValue) val;

    }

    @Override

    public void emitPause() {

        append(new AArch64PauseOp());

    }

}