/*

 * Copyright (c) 2011, 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.lir.amd64;

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

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

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

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

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

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

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

import org.graalvm.compiler.asm.Label;

import org.graalvm.compiler.asm.amd64.AMD64Address;

import org.graalvm.compiler.asm.amd64.AMD64Address.Scale;

import org.graalvm.compiler.asm.amd64.AMD64Assembler.ConditionFlag;

import org.graalvm.compiler.asm.amd64.AMD64MacroAssembler;

import org.graalvm.compiler.code.CompilationResult.JumpTable;

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

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.lir.LIRInstructionClass;

import org.graalvm.compiler.lir.LabelRef;

import org.graalvm.compiler.lir.Opcode;

import org.graalvm.compiler.lir.StandardOp;

import org.graalvm.compiler.lir.StandardOp.BlockEndOp;

import org.graalvm.compiler.lir.SwitchStrategy;

import org.graalvm.compiler.lir.SwitchStrategy.BaseSwitchClosure;

import org.graalvm.compiler.lir.Variable;

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

import jdk.vm.ci.amd64.AMD64;

import jdk.vm.ci.amd64.AMD64.CPUFeature;

import jdk.vm.ci.amd64.AMD64Kind;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.meta.AllocatableValue;

import jdk.vm.ci.meta.Constant;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.Value;

public class AMD64ControlFlow {

    public static final class ReturnOp extends AMD64BlockEndOp implements BlockEndOp {

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

        @Use({REG, ILLEGAL}) protected Value x;

        public ReturnOp(Value x) {

            super(TYPE);

            this.x = x;

        }

        @Override

        public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

            crb.frameContext.leave(crb);

            /*

             * We potentially return to the interpreter, and that's an AVX-SSE transition. The only

             * live value at this point should be the return value in either rax, or in xmm0 with

             * the upper half of the register unused, so we don't destroy any value here.

             */

            if (masm.supports(CPUFeature.AVX)) {

                masm.vzeroupper();

            }

            masm.ret(0);

        }

    }

    public static class BranchOp extends AMD64BlockEndOp implements StandardOp.BranchOp {

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

        protected final ConditionFlag condition;

        protected final LabelRef trueDestination;

        protected final LabelRef falseDestination;

        private final double trueDestinationProbability;

        public BranchOp(Condition condition, LabelRef trueDestination, LabelRef falseDestination, double trueDestinationProbability) {

            this(intCond(condition), trueDestination, falseDestination, trueDestinationProbability);

        }

        public BranchOp(ConditionFlag condition, LabelRef trueDestination, LabelRef falseDestination, double trueDestinationProbability) {

            this(TYPE, condition, trueDestination, falseDestination, trueDestinationProbability);

        }

        protected BranchOp(LIRInstructionClass<? extends BranchOp> c, ConditionFlag condition, LabelRef trueDestination, LabelRef falseDestination, double trueDestinationProbability) {

            super(c);

            this.condition = condition;

            this.trueDestination = trueDestination;

            this.falseDestination = falseDestination;

            this.trueDestinationProbability = trueDestinationProbability;

        }

        @Override

        public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

            /*

             * The strategy for emitting jumps is: If either trueDestination or falseDestination is

             * the successor block, assume the block scheduler did the correct thing and jcc to the

             * other. Otherwise, we need a jcc followed by a jmp. Use the branch probability to make

             * sure it is more likely to branch on the jcc (= less likely to execute both the jcc

             * and the jmp instead of just the jcc). In the case of loops, that means the jcc is the

             * back-edge.

             */

            if (crb.isSuccessorEdge(trueDestination)) {

                jcc(masm, true, falseDestination);

            } else if (crb.isSuccessorEdge(falseDestination)) {

                jcc(masm, false, trueDestination);

            } else if (trueDestinationProbability < 0.5) {

                jcc(masm, true, falseDestination);

                masm.jmp(trueDestination.label());

            } else {

                jcc(masm, false, trueDestination);

                masm.jmp(falseDestination.label());

            }

        }

        protected void jcc(AMD64MacroAssembler masm, boolean negate, LabelRef target) {

            masm.jcc(negate ? condition.negate() : condition, target.label());

        }

    }

    public static final class FloatBranchOp extends BranchOp {

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

        protected boolean unorderedIsTrue;

        public FloatBranchOp(Condition condition, boolean unorderedIsTrue, LabelRef trueDestination, LabelRef falseDestination, double trueDestinationProbability) {

            super(TYPE, floatCond(condition), trueDestination, falseDestination, trueDestinationProbability);

            this.unorderedIsTrue = unorderedIsTrue;

        }

        @Override

        protected void jcc(AMD64MacroAssembler masm, boolean negate, LabelRef target) {

            floatJcc(masm, negate ? condition.negate() : condition, negate ? !unorderedIsTrue : unorderedIsTrue, target.label());

        }

    }

    public static class StrategySwitchOp extends AMD64BlockEndOp {

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

        protected final Constant[] keyConstants;

        private final LabelRef[] keyTargets;

        private LabelRef defaultTarget;

        @Alive({REG}) protected Value key;

        @Temp({REG, ILLEGAL}) protected Value scratch;

        protected final SwitchStrategy strategy;

        public StrategySwitchOp(SwitchStrategy strategy, LabelRef[] keyTargets, LabelRef defaultTarget, Value key, Value scratch) {

            this(TYPE, strategy, keyTargets, defaultTarget, key, scratch);

        }

        protected StrategySwitchOp(LIRInstructionClass<? extends StrategySwitchOp> c, SwitchStrategy strategy, LabelRef[] keyTargets, LabelRef defaultTarget, Value key, Value scratch) {

            super(c);

            this.strategy = strategy;

            this.keyConstants = strategy.getKeyConstants();

            this.keyTargets = keyTargets;

            this.defaultTarget = defaultTarget;

            this.key = key;

            this.scratch = scratch;

            assert keyConstants.length == keyTargets.length;

            assert keyConstants.length == strategy.keyProbabilities.length;

        }

        @Override

        public void emitCode(final CompilationResultBuilder crb, final AMD64MacroAssembler masm) {

            strategy.run(new SwitchClosure(asRegister(key), crb, masm));

        }

        public class SwitchClosure extends BaseSwitchClosure {

            protected final Register keyRegister;

            protected final CompilationResultBuilder crb;

            protected final AMD64MacroAssembler masm;

            protected SwitchClosure(Register keyRegister, CompilationResultBuilder crb, AMD64MacroAssembler masm) {

                super(crb, masm, keyTargets, defaultTarget);

                this.keyRegister = keyRegister;

                this.crb = crb;

                this.masm = masm;

            }

            protected void emitComparison(Constant c) {

                JavaConstant jc = (JavaConstant) c;

                switch (jc.getJavaKind()) {

                    case Int:

                        long lc = jc.asLong();

                        assert NumUtil.isInt(lc);

                        masm.cmpl(keyRegister, (int) lc);

                        break;

                    case Long:

                        masm.cmpq(keyRegister, (AMD64Address) crb.asLongConstRef(jc));

                        break;

                    case Object:

                        AMD64Move.const2reg(crb, masm, asRegister(scratch), jc);

                        masm.cmpptr(keyRegister, asRegister(scratch));

                        break;

                    default:

                        throw new GraalError("switch only supported for int, long and object");

                }

            }

            @Override

            protected void conditionalJump(int index, Condition condition, Label target) {

                emitComparison(keyConstants[index]);

                masm.jcc(intCond(condition), target);

            }

        }

    }

    public static final class TableSwitchOp extends AMD64BlockEndOp {

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

        private final int lowKey;

        private final LabelRef defaultTarget;

        private final LabelRef[] targets;

        @Use protected Value index;

        @Temp({REG, HINT}) protected Value idxScratch;

        @Temp protected Value scratch;

        public TableSwitchOp(final int lowKey, final LabelRef defaultTarget, final LabelRef[] targets, Value index, Variable scratch, Variable idxScratch) {

            super(TYPE);

            this.lowKey = lowKey;

            this.defaultTarget = defaultTarget;

            this.targets = targets;

            this.index = index;

            this.scratch = scratch;

            this.idxScratch = idxScratch;

        }

        @Override

        public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

            Register indexReg = asRegister(index, AMD64Kind.DWORD);

            Register idxScratchReg = asRegister(idxScratch, AMD64Kind.DWORD);

            Register scratchReg = asRegister(scratch, AMD64Kind.QWORD);

            if (!indexReg.equals(idxScratchReg)) {

                masm.movl(idxScratchReg, indexReg);

            }

            // Compare index against jump table bounds

            int highKey = lowKey + targets.length - 1;

            if (lowKey != 0) {

                // subtract the low value from the switch value

                masm.subl(idxScratchReg, lowKey);

                masm.cmpl(idxScratchReg, highKey - lowKey);

            } else {

                masm.cmpl(idxScratchReg, highKey);

            }

            // Jump to default target if index is not within the jump table

            if (defaultTarget != null) {

                masm.jcc(ConditionFlag.Above, defaultTarget.label());

            }

            // Set scratch to address of jump table

            masm.leaq(scratchReg, new AMD64Address(AMD64.rip, 0));

            final int afterLea = masm.position();

            // Load jump table entry into scratch and jump to it

            masm.movslq(idxScratchReg, new AMD64Address(scratchReg, idxScratchReg, Scale.Times4, 0));

            masm.addq(scratchReg, idxScratchReg);

            masm.jmp(scratchReg);

            // Inserting padding so that jump table address is 4-byte aligned

            if ((masm.position() & 0x3) != 0) {

                masm.nop(4 - (masm.position() & 0x3));

            }

            // Patch LEA instruction above now that we know the position of the jump table

            // TODO this is ugly and should be done differently

            final int jumpTablePos = masm.position();

            final int leaDisplacementPosition = afterLea - 4;

            masm.emitInt(jumpTablePos - afterLea, leaDisplacementPosition);

            // Emit jump table entries

            for (LabelRef target : targets) {

                Label label = target.label();

                int offsetToJumpTableBase = masm.position() - jumpTablePos;

                if (label.isBound()) {

                    int imm32 = label.position() - jumpTablePos;

                    masm.emitInt(imm32);

                } else {

                    label.addPatchAt(masm.position());

                    masm.emitByte(0); // pseudo-opcode for jump table entry

                    masm.emitShort(offsetToJumpTableBase);

                    masm.emitByte(0); // padding to make jump table entry 4 bytes wide

                }

            }

            JumpTable jt = new JumpTable(jumpTablePos, lowKey, highKey, 4);

            crb.compilationResult.addAnnotation(jt);

        }

    }

    @Opcode("CMOVE")

    public static final class CondMoveOp extends AMD64LIRInstruction {

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

        @Def({REG, HINT}) protected Value result;

        @Alive({REG}) protected Value trueValue;

        @Use({REG, STACK, CONST}) protected Value falseValue;

        private final ConditionFlag condition;

        public CondMoveOp(Variable result, Condition condition, AllocatableValue trueValue, Value falseValue) {

            super(TYPE);

            this.result = result;

            this.condition = intCond(condition);

            this.trueValue = trueValue;

            this.falseValue = falseValue;

        }

        @Override

        public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

            cmove(crb, masm, result, false, condition, false, trueValue, falseValue);

        }

    }

    @Opcode("CMOVE")

    public static final class FloatCondMoveOp extends AMD64LIRInstruction {

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

        @Def({REG}) protected Value result;

        @Alive({REG}) protected Value trueValue;

        @Alive({REG}) protected Value falseValue;

        private final ConditionFlag condition;

        private final boolean unorderedIsTrue;

        public FloatCondMoveOp(Variable result, Condition condition, boolean unorderedIsTrue, Variable trueValue, Variable falseValue) {

            super(TYPE);

            this.result = result;

            this.condition = floatCond(condition);

            this.unorderedIsTrue = unorderedIsTrue;

            this.trueValue = trueValue;

            this.falseValue = falseValue;

        }

        @Override

        public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

            cmove(crb, masm, result, true, condition, unorderedIsTrue, trueValue, falseValue);

        }

    }

    private static void floatJcc(AMD64MacroAssembler masm, ConditionFlag condition, boolean unorderedIsTrue, Label label) {

        Label endLabel = new Label();

        if (unorderedIsTrue && !trueOnUnordered(condition)) {

            masm.jcc(ConditionFlag.Parity, label);

        } else if (!unorderedIsTrue && trueOnUnordered(condition)) {

            masm.jccb(ConditionFlag.Parity, endLabel);

        }

        masm.jcc(condition, label);

        masm.bind(endLabel);

    }

    private static void cmove(CompilationResultBuilder crb, AMD64MacroAssembler masm, Value result, boolean isFloat, ConditionFlag condition, boolean unorderedIsTrue, Value trueValue,

                    Value falseValue) {

        // check that we don't overwrite an input operand before it is used.

        assert !result.equals(trueValue);

        AMD64Move.move(crb, masm, result, falseValue);

        cmove(crb, masm, result, condition, trueValue);

        if (isFloat) {

            if (unorderedIsTrue && !trueOnUnordered(condition)) {

                cmove(crb, masm, result, ConditionFlag.Parity, trueValue);

            } else if (!unorderedIsTrue && trueOnUnordered(condition)) {

                cmove(crb, masm, result, ConditionFlag.Parity, falseValue);

            }

        }

    }

    private static void cmove(CompilationResultBuilder crb, AMD64MacroAssembler masm, Value result, ConditionFlag cond, Value other) {

        if (isRegister(other)) {

            assert !asRegister(other).equals(asRegister(result)) : "other already overwritten by previous move";

            switch ((AMD64Kind) other.getPlatformKind()) {

                case BYTE:

                case WORD:

                case DWORD:

                    masm.cmovl(cond, asRegister(result), asRegister(other));

                    break;

                case QWORD:

                    masm.cmovq(cond, asRegister(result), asRegister(other));

                    break;

                default:

                    throw GraalError.shouldNotReachHere();

            }

        } else {

            AMD64Address addr = (AMD64Address) crb.asAddress(other);

            switch ((AMD64Kind) other.getPlatformKind()) {

                case BYTE:

                case WORD:

                case DWORD:

                    masm.cmovl(cond, asRegister(result), addr);

                    break;

                case QWORD:

                    masm.cmovq(cond, asRegister(result), addr);

                    break;

                default:

                    throw GraalError.shouldNotReachHere();

            }

        }

    }

    private static ConditionFlag intCond(Condition cond) {

        switch (cond) {

            case EQ:

                return ConditionFlag.Equal;

            case NE:

                return ConditionFlag.NotEqual;

            case LT:

                return ConditionFlag.Less;

            case LE:

                return ConditionFlag.LessEqual;

            case GE:

                return ConditionFlag.GreaterEqual;

            case GT:

                return ConditionFlag.Greater;

            case BE:

                return ConditionFlag.BelowEqual;

            case AE:

                return ConditionFlag.AboveEqual;

            case AT:

                return ConditionFlag.Above;

            case BT:

                return ConditionFlag.Below;

            default:

                throw GraalError.shouldNotReachHere();

        }

    }

    private static ConditionFlag floatCond(Condition cond) {

        switch (cond) {

            case EQ:

                return ConditionFlag.Equal;

            case NE:

                return ConditionFlag.NotEqual;

            case LT:

                return ConditionFlag.Below;

            case LE:

                return ConditionFlag.BelowEqual;

            case GE:

                return ConditionFlag.AboveEqual;

            case GT:

                return ConditionFlag.Above;

            default:

                throw GraalError.shouldNotReachHere();

        }

    }

    private static boolean trueOnUnordered(ConditionFlag condition) {

        switch (condition) {

            case AboveEqual:

            case NotEqual:

            case Above:

            case Less:

            case Overflow:

                return false;

            case Equal:

            case BelowEqual:

            case Below:

            case GreaterEqual:

            case NoOverflow:

                return true;

            default:

                throw GraalError.shouldNotReachHere();

        }

    }

}