/*

 * Copyright (c) 2009, 2019, 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.asm;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.function.Consumer;

import org.graalvm.compiler.debug.GraalError;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.code.StackSlot;

import jdk.vm.ci.code.TargetDescription;

/**

 * The platform-independent base class for the assembler.

 */

public abstract class Assembler {

    public abstract static class CodeAnnotation {

        /**

         * The position (bytes from the beginning of the method) of the annotated instruction.

         */

        public final int instructionPosition;

        protected CodeAnnotation(int instructionStartPosition) {

            this.instructionPosition = instructionStartPosition;

        }

    }

    public final TargetDescription target;

    private List<LabelHint> jumpDisplacementHints;

    /**

     * Labels with instructions to be patched when it is {@linkplain Label#bind bound}.

     */

    Label labelsWithPatches;

    /**

     * Backing code buffer.

     */

    private final Buffer codeBuffer;

    protected Consumer<CodeAnnotation> codePatchingAnnotationConsumer;

    public Assembler(TargetDescription target) {

        this.target = target;

        this.codeBuffer = new Buffer(target.arch.getByteOrder());

    }

    public void setCodePatchingAnnotationConsumer(Consumer<CodeAnnotation> codeAnnotationConsumer) {

        assert this.codePatchingAnnotationConsumer == null : "overwriting existing value";

        this.codePatchingAnnotationConsumer = codeAnnotationConsumer;

    }

    /**

     * Returns the current position of the underlying code buffer.

     *

     * @return current position in code buffer

     */

    public int position() {

        return codeBuffer.position();

    }

    public final void emitByte(int x) {

        codeBuffer.emitByte(x);

    }

    public final void emitShort(int x) {

        codeBuffer.emitShort(x);

    }

    public final void emitInt(int x) {

        codeBuffer.emitInt(x);

    }

    public final void emitLong(long x) {

        codeBuffer.emitLong(x);

    }

    public final void emitByte(int b, int pos) {

        codeBuffer.emitByte(b, pos);

    }

    public final void emitShort(int b, int pos) {

        codeBuffer.emitShort(b, pos);

    }

    public final void emitInt(int b, int pos) {

        codeBuffer.emitInt(b, pos);

    }

    public final void emitLong(long b, int pos) {

        codeBuffer.emitLong(b, pos);

    }

    public final int getByte(int pos) {

        return codeBuffer.getByte(pos);

    }

    public final int getShort(int pos) {

        return codeBuffer.getShort(pos);

    }

    public final int getInt(int pos) {

        return codeBuffer.getInt(pos);

    }

    private static final String NEWLINE = System.lineSeparator();

    /**

     * Some GPU architectures have a text based encoding.

     */

    public final void emitString(String x) {

        emitString0("\t");  // XXX REMOVE ME pretty-printing

        emitString0(x);

        emitString0(NEWLINE);

    }

    // XXX for pretty-printing

    public final void emitString0(String x) {

        codeBuffer.emitBytes(x.getBytes(), 0, x.length());

    }

    public void emitString(String s, int pos) {

        codeBuffer.emitBytes(s.getBytes(), pos);

    }

    /**

     * Closes this assembler. No extra data can be written to this assembler after this call.

     *

     * @param trimmedCopy if {@code true}, then a copy of the underlying byte array up to (but not

     *            including) {@code position()} is returned

     * @return the data in this buffer or a trimmed copy if {@code trimmedCopy} is {@code true}

     */

    public byte[] close(boolean trimmedCopy) {

        checkAndClearLabelsWithPatches();

        return codeBuffer.close(trimmedCopy);

    }

    public byte[] copy(int start, int end) {

        return codeBuffer.copyData(start, end);

    }

    private void checkAndClearLabelsWithPatches() throws InternalError {

        Label label = labelsWithPatches;

        while (label != null) {

            if (label.patchPositions != null) {

                throw new GraalError("Label used by instructions at following offsets has not been bound: %s", label.patchPositions);

            }

            Label next = label.nextWithPatches;

            label.nextWithPatches = null;

            label = next;

        }

        labelsWithPatches = null;

    }

    public void bind(Label l) {

        assert !l.isBound() : "can bind label only once";

        l.bind(position(), this);

    }

    public abstract void align(int modulus);

    public abstract void jmp(Label l);

    protected abstract void patchJumpTarget(int branch, int jumpTarget);

    private Map<Label, String> nameMap;

    /**

     * Creates a name for a label.

     *

     * @param l the label for which a name is being created

     * @param id a label identifier that is unique with the scope of this assembler

     * @return a label name in the form of "L123"

     */

    protected String createLabelName(Label l, int id) {

        return "L" + id;

    }

    /**

     * Gets a name for a label, creating it if it does not yet exist. By default, the returned name

     * is only unique with the scope of this assembler.

     */

    public String nameOf(Label l) {

        if (nameMap == null) {

            nameMap = new HashMap<>();

        }

        String name = nameMap.get(l);

        if (name == null) {

            name = createLabelName(l, nameMap.size());

            nameMap.put(l, name);

        }

        return name;

    }

    /**

     * This is used by the CompilationResultBuilder to convert a {@link StackSlot} to an

     * {@link AbstractAddress}.

     */

    public abstract AbstractAddress makeAddress(Register base, int displacement);

    /**

     * Returns a target specific placeholder address that can be used for code patching.

     *

     * @param instructionStartPosition The start of the instruction, i.e., the value that is used as

     *            the key for looking up placeholder patching information.

     */

    public abstract AbstractAddress getPlaceholder(int instructionStartPosition);

    /**

     * Emits a NOP instruction to advance the current PC.

     */

    public abstract void ensureUniquePC();

    public void reset() {

        codeBuffer.reset();

        captureLabelPositions();

    }

    private void captureLabelPositions() {

        if (jumpDisplacementHints == null) {

            return;

        }

        for (LabelHint request : this.jumpDisplacementHints) {

            request.capture();

        }

    }

    public LabelHint requestLabelHint(Label label) {

        if (jumpDisplacementHints == null) {

            jumpDisplacementHints = new ArrayList<>();

        }

        LabelHint hint = new LabelHint(label, position());

        this.jumpDisplacementHints.add(hint);

        return hint;

    }

    public InstructionCounter getInstructionCounter() {

        throw new UnsupportedOperationException("Instruction counter is not implemented for " + this);

    }

    public static class LabelHint {

        private Label label;

        private int forPosition;

        private int capturedTarget = -1;

        protected LabelHint(Label label, int lastPosition) {

            super();

            this.label = label;

            this.forPosition = lastPosition;

        }

        protected void capture() {

            this.capturedTarget = label.position();

        }

        public int getTarget() {

            assert isValid();

            return capturedTarget;

        }

        public int getPosition() {

            assert isValid();

            return forPosition;

        }

        public boolean isValid() {

            return capturedTarget >= 0;

        }

    }

    /**

     * Instruction counter class which gives the user of the assembler to count different kinds of

     * instructions in the generated assembler code.

     */

    public interface InstructionCounter {

        String[] getSupportedInstructionTypes();

        int[] countInstructions(String[] instructionTypes, int beginPc, int endPc);

    }

}