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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.hotspot.amd64;

import static org.graalvm.compiler.core.common.NumUtil.isInt;

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

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

import static jdk.vm.ci.amd64.AMD64.rax;

import static jdk.vm.ci.amd64.AMD64.rip;

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

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

import org.graalvm.compiler.core.common.LIRKind;

import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;

import org.graalvm.compiler.lir.LIRFrameState;

import org.graalvm.compiler.lir.LIRInstructionClass;

import org.graalvm.compiler.lir.Opcode;

import org.graalvm.compiler.lir.amd64.AMD64LIRInstruction;

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

import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.code.RegisterValue;

import jdk.vm.ci.code.site.InfopointReason;

import jdk.vm.ci.meta.AllocatableValue;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.Value;

/**

 * Emits a safepoint poll.

 */

@Opcode("SAFEPOINT")

public final class AMD64HotSpotSafepointOp extends AMD64LIRInstruction {

    public static final LIRInstructionClass<AMD64HotSpotSafepointOp> TYPE = LIRInstructionClass.create(AMD64HotSpotSafepointOp.class);

    @State protected LIRFrameState state;

    @Temp({OperandFlag.REG, OperandFlag.ILLEGAL}) private AllocatableValue temp;

    private final GraalHotSpotVMConfig config;

    private final Register thread;

    public AMD64HotSpotSafepointOp(LIRFrameState state, GraalHotSpotVMConfig config, NodeLIRBuilderTool tool, Register thread) {

        super(TYPE);

        this.state = state;

        this.config = config;

        this.thread = thread;

        if (config.threadLocalHandshakes || isPollingPageFar(config) || ImmutableCode.getValue(tool.getOptions())) {

            temp = tool.getLIRGeneratorTool().newVariable(LIRKind.value(tool.getLIRGeneratorTool().target().arch.getWordKind()));

        } else {

            // Don't waste a register if it's unneeded

            temp = Value.ILLEGAL;

        }

    }

    @Override

    public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler asm) {

        emitCode(crb, asm, config, false, state, thread, temp instanceof RegisterValue ? ((RegisterValue) temp).getRegister() : null);

    }

    public static void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler asm, GraalHotSpotVMConfig config, boolean atReturn, LIRFrameState state, Register thread, Register scratch) {

        if (config.threadLocalHandshakes) {

            emitThreadLocalPoll(crb, asm, config, atReturn, state, thread, scratch);

        } else {

            emitGlobalPoll(crb, asm, config, atReturn, state, scratch);

        }

    }

    /**

     * Tests if the polling page address can be reached from the code cache with 32-bit

     * displacements.

     */

    private static boolean isPollingPageFar(GraalHotSpotVMConfig config) {

        final long pollingPageAddress = config.safepointPollingAddress;

        return config.forceUnreachable || !isInt(pollingPageAddress - config.codeCacheLowBound) || !isInt(pollingPageAddress - config.codeCacheHighBound);

    }

    private static void emitGlobalPoll(CompilationResultBuilder crb, AMD64MacroAssembler asm, GraalHotSpotVMConfig config, boolean atReturn, LIRFrameState state, Register scratch) {

        assert !atReturn || state == null : "state is unneeded at return";

        if (ImmutableCode.getValue(crb.getOptions())) {

            JavaKind hostWordKind = JavaKind.Long;

            int alignment = hostWordKind.getBitCount() / Byte.SIZE;

            JavaConstant pollingPageAddress = JavaConstant.forIntegerKind(hostWordKind, config.safepointPollingAddress);

            // This move will be patched to load the safepoint page from a data segment

            // co-located with the immutable code.

            if (GeneratePIC.getValue(crb.getOptions())) {

                asm.movq(scratch, asm.getPlaceholder(-1));

            } else {

                asm.movq(scratch, (AMD64Address) crb.recordDataReferenceInCode(pollingPageAddress, alignment));

            }

            final int pos = asm.position();

            crb.recordMark(atReturn ? config.MARKID_POLL_RETURN_FAR : config.MARKID_POLL_FAR);

            if (state != null) {

                crb.recordInfopoint(pos, state, InfopointReason.SAFEPOINT);

            }

            asm.testl(rax, new AMD64Address(scratch));

        } else if (isPollingPageFar(config)) {

            asm.movq(scratch, config.safepointPollingAddress);

            crb.recordMark(atReturn ? config.MARKID_POLL_RETURN_FAR : config.MARKID_POLL_FAR);

            final int pos = asm.position();

            if (state != null) {

                crb.recordInfopoint(pos, state, InfopointReason.SAFEPOINT);

            }

            asm.testl(rax, new AMD64Address(scratch));

        } else {

            crb.recordMark(atReturn ? config.MARKID_POLL_RETURN_NEAR : config.MARKID_POLL_NEAR);

            final int pos = asm.position();

            if (state != null) {

                crb.recordInfopoint(pos, state, InfopointReason.SAFEPOINT);

            }

            // The C++ code transforms the polling page offset into an RIP displacement

            // to the real address at that offset in the polling page.

            asm.testl(rax, new AMD64Address(rip, 0));

        }

    }

    private static void emitThreadLocalPoll(CompilationResultBuilder crb, AMD64MacroAssembler asm, GraalHotSpotVMConfig config, boolean atReturn, LIRFrameState state, Register thread,

                    Register scratch) {

        assert !atReturn || state == null : "state is unneeded at return";

        assert config.threadPollingPageOffset >= 0;

        asm.movptr(scratch, new AMD64Address(thread, config.threadPollingPageOffset));

        crb.recordMark(atReturn ? config.MARKID_POLL_RETURN_FAR : config.MARKID_POLL_FAR);

        final int pos = asm.position();

        if (state != null) {

            crb.recordInfopoint(pos, state, InfopointReason.SAFEPOINT);

        }

        asm.testl(rax, new AMD64Address(scratch));

    }

}