/*
 * Copyright (c) 2011, 2015, 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
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 */
package org.graalvm.compiler.replacements.amd64;

import org.graalvm.compiler.api.replacements.ClassSubstitution;
import org.graalvm.compiler.api.replacements.MethodSubstitution;
import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;
import org.graalvm.compiler.graph.Node.ConstantNodeParameter;
import org.graalvm.compiler.graph.Node.NodeIntrinsic;
import org.graalvm.compiler.nodes.extended.ForeignCallNode;
import org.graalvm.compiler.replacements.nodes.UnaryMathIntrinsicNode;
import org.graalvm.compiler.replacements.nodes.UnaryMathIntrinsicNode.UnaryOperation;

// JaCoCo Exclude

/**
 * Substitutions for some {@link java.lang.Math} methods that leverage AMD64 instructions for
 * selected input values.
 */
@ClassSubstitution(Math.class)
public class AMD64MathSubstitutions {

    private static final double PI_4 = Math.PI / 4;

    // NOTE on snippets below:
    // Math.sin(), .cos() and .tan() guarantee a value within 1 ULP of the
    // exact result, but x87 trigonometric FPU instructions are only that
    // accurate within [-pi/4, pi/4]. Examine the passed value and provide
    // a slow path for inputs outside of that interval.

    @MethodSubstitution
    public static double sin(double x) {
        if (Math.abs(x) < PI_4) {
            return UnaryMathIntrinsicNode.compute(x, UnaryOperation.SIN);
        } else {
            return callDouble1(UnaryOperation.SIN.foreignCallDescriptor, x);
        }
    }

    @MethodSubstitution
    public static double cos(double x) {
        if (Math.abs(x) < PI_4) {
            return UnaryMathIntrinsicNode.compute(x, UnaryOperation.COS);
        } else {
            return callDouble1(UnaryOperation.COS.foreignCallDescriptor, x);
        }
    }

    @MethodSubstitution
    public static double tan(double x) {
        if (Math.abs(x) < PI_4) {
            return UnaryMathIntrinsicNode.compute(x, UnaryOperation.TAN);
        } else {
            return callDouble1(UnaryOperation.TAN.foreignCallDescriptor, x);
        }
    }

    @NodeIntrinsic(value = ForeignCallNode.class)
    private static native double callDouble1(@ConstantNodeParameter ForeignCallDescriptor descriptor, double value);

    @NodeIntrinsic(value = ForeignCallNode.class)
    private static native double callDouble2(@ConstantNodeParameter ForeignCallDescriptor descriptor, double a, double b);
}