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package org.graalvm.compiler.hotspot.amd64;

import static org.graalvm.compiler.hotspot.HotSpotBackend.UNWIND_EXCEPTION_TO_CALLER;
import static org.graalvm.compiler.lir.LIRInstruction.OperandFlag.REG;
import static jdk.vm.ci.amd64.AMD64.rsp;
import static jdk.vm.ci.code.ValueUtil.asRegister;

import org.graalvm.compiler.asm.amd64.AMD64Address;
import org.graalvm.compiler.asm.amd64.AMD64MacroAssembler;
import org.graalvm.compiler.core.common.spi.ForeignCallLinkage;
import org.graalvm.compiler.hotspot.stubs.UnwindExceptionToCallerStub;
import org.graalvm.compiler.lir.LIRInstructionClass;
import org.graalvm.compiler.lir.Opcode;
import org.graalvm.compiler.lir.amd64.AMD64Call;
import org.graalvm.compiler.lir.asm.CompilationResultBuilder;

import jdk.vm.ci.code.CallingConvention;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.RegisterValue;

/**
 * Removes the current frame and jumps to the {@link UnwindExceptionToCallerStub}.
 */
@Opcode("UNWIND")
final class AMD64HotSpotUnwindOp extends AMD64HotSpotEpilogueBlockEndOp {
    public static final LIRInstructionClass<AMD64HotSpotUnwindOp> TYPE = LIRInstructionClass.create(AMD64HotSpotUnwindOp.class);

    @Use({REG}) protected RegisterValue exception;

    AMD64HotSpotUnwindOp(RegisterValue exception) {
        super(TYPE);
        this.exception = exception;
    }

    @Override
    public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {
        leaveFrameAndRestoreRbp(crb, masm);

        ForeignCallLinkage linkage = crb.foreignCalls.lookupForeignCall(UNWIND_EXCEPTION_TO_CALLER);
        CallingConvention cc = linkage.getOutgoingCallingConvention();
        assert cc.getArgumentCount() == 2;
        assert exception.equals(cc.getArgument(0));

        // Get return address (is on top of stack after leave).
        Register returnAddress = asRegister(cc.getArgument(1));
        masm.movq(returnAddress, new AMD64Address(rsp, 0));

        AMD64Call.directJmp(crb, masm, linkage, null);
    }
}
