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 * 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

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package org.graalvm.compiler.nodes.calc;

import static org.graalvm.compiler.core.common.GraalOptions.GeneratePIC;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_1;

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

import org.graalvm.compiler.core.common.type.AbstractObjectStamp;

import org.graalvm.compiler.core.common.type.AbstractPointerStamp;

import org.graalvm.compiler.core.common.type.IntegerStamp;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.graph.spi.Canonicalizable;

import org.graalvm.compiler.graph.spi.CanonicalizerTool;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.BinaryOpLogicNode;

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.LogicConstantNode;

import org.graalvm.compiler.nodes.LogicNegationNode;

import org.graalvm.compiler.nodes.LogicNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.ValueNode;

import jdk.vm.ci.meta.Constant;

import jdk.vm.ci.meta.ConstantReflectionProvider;

@NodeInfo(cycles = CYCLES_1)

public abstract class CompareNode extends BinaryOpLogicNode implements Canonicalizable.Binary<ValueNode> {

    public static final NodeClass<CompareNode> TYPE = NodeClass.create(CompareNode.class);

    protected final Condition condition;

    protected final boolean unorderedIsTrue;

    /**

     * Constructs a new Compare instruction.

     *

     * @param x the instruction producing the first input to the instruction

     * @param y the instruction that produces the second input to this instruction

     */

    protected CompareNode(NodeClass<? extends CompareNode> c, Condition condition, boolean unorderedIsTrue, ValueNode x, ValueNode y) {

        super(c, x, y);

        this.condition = condition;

        this.unorderedIsTrue = unorderedIsTrue;

    }

    /**

     * Gets the condition (comparison operation) for this instruction.

     *

     * @return the condition

     */

    public final Condition condition() {

        return condition;

    }

    /**

     * Checks whether unordered inputs mean true or false (only applies to float operations).

     *

     * @return {@code true} if unordered inputs produce true

     */

    public final boolean unorderedIsTrue() {

        return this.unorderedIsTrue;

    }

    private ValueNode optimizeConditional(Constant constant, ConditionalNode conditionalNode, ConstantReflectionProvider constantReflection, Condition cond) {

        Constant trueConstant = conditionalNode.trueValue().asConstant();

        Constant falseConstant = conditionalNode.falseValue().asConstant();

        if (falseConstant != null && trueConstant != null && constantReflection != null) {

            boolean trueResult = cond.foldCondition(trueConstant, constant, constantReflection, unorderedIsTrue());

            boolean falseResult = cond.foldCondition(falseConstant, constant, constantReflection, unorderedIsTrue());

            if (trueResult == falseResult) {

                return LogicConstantNode.forBoolean(trueResult);

            } else {

                if (trueResult) {

                    assert falseResult == false;

                    return conditionalNode.condition();

                } else {

                    assert falseResult == true;

                    return LogicNegationNode.create(conditionalNode.condition());

                }

            }

        }

        return this;

    }

    protected ValueNode optimizeNormalizeCmp(Constant constant, NormalizeCompareNode normalizeNode, boolean mirrored) {

        throw new GraalError("NormalizeCompareNode connected to %s (%s %s %s)", this, constant, normalizeNode, mirrored);

    }

    @Override

    public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {

        ConstantReflectionProvider constantReflection = tool.getConstantReflection();

        LogicNode constantCondition = tryConstantFold(condition(), forX, forY, constantReflection, unorderedIsTrue());

        if (constantCondition != null) {

            return constantCondition;

        }

        ValueNode result;

        if (forX.isConstant()) {

            if ((result = canonicalizeSymmetricConstant(tool, forX.asConstant(), forY, true)) != this) {

                return result;

            }

        } else if (forY.isConstant()) {

            if ((result = canonicalizeSymmetricConstant(tool, forY.asConstant(), forX, false)) != this) {

                return result;

            }

        } else if (forX instanceof ConvertNode && forY instanceof ConvertNode) {

            ConvertNode convertX = (ConvertNode) forX;

            ConvertNode convertY = (ConvertNode) forY;

            if (convertX.preservesOrder(condition()) && convertY.preservesOrder(condition()) && convertX.getValue().stamp().isCompatible(convertY.getValue().stamp())) {

                boolean supported = true;

                if (convertX.getValue().stamp() instanceof IntegerStamp) {

                    IntegerStamp intStamp = (IntegerStamp) convertX.getValue().stamp();

                    supported = tool.supportSubwordCompare(intStamp.getBits());

                }

                if (supported) {

                    if ((forX instanceof ZeroExtendNode || forX instanceof SignExtendNode) && multiUsage) {

                        // Do not perform for zero or sign extend if there are multiple usages of

                        // the value.

                        return this;

                    }

                    return duplicateModified(convertX.getValue(), convertY.getValue());

                }

            }

        }

        return this;

    }

    public static LogicNode tryConstantFold(Condition condition, ValueNode forX, ValueNode forY, ConstantReflectionProvider constantReflection, boolean unorderedIsTrue) {

        if (forX.isConstant() && forY.isConstant() && constantReflection != null) {

            return LogicConstantNode.forBoolean(condition.foldCondition(forX.asConstant(), forY.asConstant(), constantReflection, unorderedIsTrue));

        }

        return null;

    }

    /**

     * Does this operation represent an identity check such that for x == y, x is exactly the same

     * thing as y. This is generally true except for some floating point comparisons.

     *

     * @return true for identity comparisons

     */

    public boolean isIdentityComparison() {

        return condition == Condition.EQ;

    }

    protected abstract LogicNode duplicateModified(ValueNode newX, ValueNode newY);

    protected ValueNode canonicalizeSymmetricConstant(CanonicalizerTool tool, Constant constant, ValueNode nonConstant, boolean mirrored) {

        if (nonConstant instanceof ConditionalNode) {

            return optimizeConditional(constant, (ConditionalNode) nonConstant, tool.getConstantReflection(), mirrored ? condition().mirror() : condition());

        } else if (nonConstant instanceof NormalizeCompareNode) {

            return optimizeNormalizeCmp(constant, (NormalizeCompareNode) nonConstant, mirrored);

        } else if (nonConstant instanceof ConvertNode) {

            ConvertNode convert = (ConvertNode) nonConstant;

            if ((convert instanceof ZeroExtendNode || convert instanceof SignExtendNode) && multiUsage) {

                // Do not perform for zero or sign extend if it could introduce

                // new live values.

                return this;

            }

            boolean supported = true;

            if (convert.getValue().stamp() instanceof IntegerStamp) {

                IntegerStamp intStamp = (IntegerStamp) convert.getValue().stamp();

                supported = tool.supportSubwordCompare(intStamp.getBits());

            }

            if (supported) {

                ConstantNode newConstant = canonicalConvertConstant(tool, convert, constant);

                if (newConstant != null) {

                    if (mirrored) {

                        return duplicateModified(newConstant, convert.getValue());

                    } else {

                        return duplicateModified(convert.getValue(), newConstant);

                    }

                }

            }

        }

        return this;

    }

    private ConstantNode canonicalConvertConstant(CanonicalizerTool tool, ConvertNode convert, Constant constant) {

        ConstantReflectionProvider constantReflection = tool.getConstantReflection();

        if (convert.preservesOrder(condition(), constant, constantReflection)) {

            Constant reverseConverted = convert.reverse(constant, constantReflection);

            if (reverseConverted != null && convert.convert(reverseConverted, constantReflection).equals(constant)) {

                    // We always want uncompressed constants

                    return null;

                }

                return ConstantNode.forConstant(convert.getValue().stamp(), reverseConverted, tool.getMetaAccess());

            }

        }

        return null;

    }

    public static LogicNode createCompareNode(StructuredGraph graph, Condition condition, ValueNode x, ValueNode y, ConstantReflectionProvider constantReflection) {

        LogicNode result = createCompareNode(condition, x, y, constantReflection);

        return (result.graph() == null ? graph.unique(result) : result);

    }

    public static LogicNode createCompareNode(Condition condition, ValueNode x, ValueNode y, ConstantReflectionProvider constantReflection) {

        assert x.getStackKind() == y.getStackKind();

        assert !x.getStackKind().isNumericFloat();

        LogicNode comparison;

        if (condition == Condition.EQ) {

            if (x.stamp() instanceof AbstractObjectStamp) {

                comparison = ObjectEqualsNode.create(x, y, constantReflection);

            } else if (x.stamp() instanceof AbstractPointerStamp) {

                comparison = PointerEqualsNode.create(x, y);

            } else {

                assert x.getStackKind().isNumericInteger();

                comparison = IntegerEqualsNode.create(x, y, constantReflection);

            }

        } else if (condition == Condition.LT) {

            assert x.getStackKind().isNumericInteger();

            comparison = IntegerLessThanNode.create(x, y, constantReflection);

        } else {

            assert condition == Condition.BT;

            assert x.getStackKind().isNumericInteger();

            comparison = IntegerBelowNode.create(x, y, constantReflection);

        }

        return comparison;

    }

}