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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.asm.amd64;

import jdk.vm.ci.code.Register;

import org.graalvm.compiler.asm.AbstractAddress;

/**

 * Represents an address in target machine memory, specified via some combination of a base

 * register, an index register, a displacement and a scale. Note that the base and index registers

 * may be a variable that will get a register assigned later by the register allocator.

 */

public final class AMD64Address extends AbstractAddress {

    private final Register base;

    private final Register index;

    private final Scale scale;

    private final int displacement;

    /**

     * The start of the instruction, i.e., the value that is used as the key for looking up

     * placeholder patching information. Only used for {@link AMD64Assembler#getPlaceholder

     * placeholder addresses}.

     */

    final int instructionStartPosition;

    /**

     * Creates an {@link AMD64Address} with given base register, no scaling and no displacement.

     *

     * @param base the base register

     */

    public AMD64Address(Register base) {

        this(base, Register.None, Scale.Times1, 0);

    }

    /**

     * Creates an {@link AMD64Address} with given base register, no scaling and a given

     * displacement.

     *

     * @param base the base register

     * @param displacement the displacement

     */

    public AMD64Address(Register base, int displacement) {

        this(base, Register.None, Scale.Times1, displacement);

    }

    /**

     * Creates an {@link AMD64Address} with given base and index registers, scaling and 0

     * displacement.

     *

     * @param base the base register

     * @param index the index register

     * @param scale the scaling factor

     */

    public AMD64Address(Register base, Register index, Scale scale) {

        this(base, index, scale, 0, -1);

    }

    /**

     * Creates an {@link AMD64Address} with given base and index registers, scaling and

     * displacement. This is the most general constructor.

     *

     * @param base the base register

     * @param index the index register

     * @param scale the scaling factor

     * @param displacement the displacement

     */

    public AMD64Address(Register base, Register index, Scale scale, int displacement) {

        this(base, index, scale, displacement, -1);

    }

    AMD64Address(Register base, Register index, Scale scale, int displacement, int instructionStartPosition) {

        this.base = base;

        this.index = index;

        this.scale = scale;

        this.displacement = displacement;

        this.instructionStartPosition = instructionStartPosition;

        assert scale != null;

    }

    /**

     * A scaling factor used in the SIB addressing mode.

     */

    public enum Scale {

        Times1(1, 0),

        Times2(2, 1),

        Times4(4, 2),

        Times8(8, 3);

        Scale(int value, int log2) {

            this.value = value;

            this.log2 = log2;

        }

        /**

         * The value (or multiplier) of this scale.

         */

        public final int value;

        /**

         * The {@linkplain #value value} of this scale log 2.

         */

        public final int log2;

        public static Scale fromInt(int scale) {

            switch (scale) {

                case 1:

                    return Times1;

                case 2:

                    return Times2;

                case 4:

                    return Times4;

                case 8:

                    return Times8;

                default:

                    return null;

            }

        }

        public static Scale fromShift(int shift) {

            switch (shift) {

                case 0:

                    return Times1;

                case 1:

                    return Times2;

                case 2:

                    return Times4;

                case 3:

                    return Times8;

                default:

                    return null;

            }

        }

    }

    @Override

    public String toString() {

        StringBuilder s = new StringBuilder();

        s.append("[");

        String sep = "";

        if (!getBase().equals(Register.None)) {

            s.append(getBase());

            sep = " + ";

        }

        if (!getIndex().equals(Register.None)) {

            s.append(sep).append(getIndex()).append(" * ").append(getScale().value);

            sep = " + ";

        }

        if (getDisplacement() < 0) {

            s.append(" - ").append(-getDisplacement());

        } else if (getDisplacement() > 0) {

            s.append(sep).append(getDisplacement());

        }

        s.append("]");

        return s.toString();

    }

    /**

     * @return Base register that defines the start of the address computation. If not present, is

     *         denoted by {@link Register#None}.

     */

    public Register getBase() {

        return base;

    }

    /**

     * @return Index register, the value of which (possibly scaled by {@link #getScale}) is added to

     *         {@link #getBase}. If not present, is denoted by {@link Register#None}.

     */

    public Register getIndex() {

        return index;

    }

    /**

     * @return Scaling factor for indexing, dependent on target operand size.

     */

    public Scale getScale() {

        return scale;

    }

    /**

     * @return Optional additive displacement.

     */

    public int getDisplacement() {

        return displacement;

    }

}