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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
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package org.graalvm.compiler.hotspot.aarch64;

import static jdk.vm.ci.aarch64.AArch64.r0;
import static jdk.vm.ci.aarch64.AArch64.r1;
import static jdk.vm.ci.aarch64.AArch64.r10;
import static jdk.vm.ci.aarch64.AArch64.r11;
import static jdk.vm.ci.aarch64.AArch64.r12;
import static jdk.vm.ci.aarch64.AArch64.r13;
import static jdk.vm.ci.aarch64.AArch64.r14;
import static jdk.vm.ci.aarch64.AArch64.r15;
import static jdk.vm.ci.aarch64.AArch64.r16;
import static jdk.vm.ci.aarch64.AArch64.r17;
import static jdk.vm.ci.aarch64.AArch64.r18;
import static jdk.vm.ci.aarch64.AArch64.r19;
import static jdk.vm.ci.aarch64.AArch64.r2;
import static jdk.vm.ci.aarch64.AArch64.r20;
import static jdk.vm.ci.aarch64.AArch64.r21;
import static jdk.vm.ci.aarch64.AArch64.r22;
import static jdk.vm.ci.aarch64.AArch64.r23;
import static jdk.vm.ci.aarch64.AArch64.r24;
import static jdk.vm.ci.aarch64.AArch64.r25;
import static jdk.vm.ci.aarch64.AArch64.r26;
import static jdk.vm.ci.aarch64.AArch64.r28;
import static jdk.vm.ci.aarch64.AArch64.r29;
import static jdk.vm.ci.aarch64.AArch64.r3;
import static jdk.vm.ci.aarch64.AArch64.r30;
import static jdk.vm.ci.aarch64.AArch64.r31;
import static jdk.vm.ci.aarch64.AArch64.r4;
import static jdk.vm.ci.aarch64.AArch64.r5;
import static jdk.vm.ci.aarch64.AArch64.r6;
import static jdk.vm.ci.aarch64.AArch64.r7;
import static jdk.vm.ci.aarch64.AArch64.r8;
import static jdk.vm.ci.aarch64.AArch64.r9;
import static jdk.vm.ci.aarch64.AArch64.v0;
import static jdk.vm.ci.aarch64.AArch64.v1;
import static jdk.vm.ci.aarch64.AArch64.v10;
import static jdk.vm.ci.aarch64.AArch64.v11;
import static jdk.vm.ci.aarch64.AArch64.v12;
import static jdk.vm.ci.aarch64.AArch64.v13;
import static jdk.vm.ci.aarch64.AArch64.v14;
import static jdk.vm.ci.aarch64.AArch64.v15;
import static jdk.vm.ci.aarch64.AArch64.v16;
import static jdk.vm.ci.aarch64.AArch64.v17;
import static jdk.vm.ci.aarch64.AArch64.v18;
import static jdk.vm.ci.aarch64.AArch64.v19;
import static jdk.vm.ci.aarch64.AArch64.v2;
import static jdk.vm.ci.aarch64.AArch64.v20;
import static jdk.vm.ci.aarch64.AArch64.v21;
import static jdk.vm.ci.aarch64.AArch64.v22;
import static jdk.vm.ci.aarch64.AArch64.v23;
import static jdk.vm.ci.aarch64.AArch64.v24;
import static jdk.vm.ci.aarch64.AArch64.v25;
import static jdk.vm.ci.aarch64.AArch64.v26;
import static jdk.vm.ci.aarch64.AArch64.v27;
import static jdk.vm.ci.aarch64.AArch64.v28;
import static jdk.vm.ci.aarch64.AArch64.v29;
import static jdk.vm.ci.aarch64.AArch64.v3;
import static jdk.vm.ci.aarch64.AArch64.v30;
import static jdk.vm.ci.aarch64.AArch64.v31;
import static jdk.vm.ci.aarch64.AArch64.v4;
import static jdk.vm.ci.aarch64.AArch64.v5;
import static jdk.vm.ci.aarch64.AArch64.v6;
import static jdk.vm.ci.aarch64.AArch64.v7;
import static jdk.vm.ci.aarch64.AArch64.v8;
import static jdk.vm.ci.aarch64.AArch64.v9;

import java.util.ArrayList;
import java.util.BitSet;

import org.graalvm.compiler.core.common.alloc.RegisterAllocationConfig;

import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.RegisterArray;
import jdk.vm.ci.code.RegisterConfig;

public class AArch64HotSpotRegisterAllocationConfig extends RegisterAllocationConfig {

    
Excluding r27 is a temporary solution until we exclude r27 unconditionally at AArch64HotSpotRegisterConfig. The underlying reason is that HotSpot does not intend to support r27 as an allocatable register. This register is excluded from callee-saved register at cpu/aarch64/sharedRuntime_aarch64.cpp:RegisterSaver::save_live_registers, and may lead to dereferencing unknown value from the stack at share/runtime/stackValue.cpp:StackValue::create_stack_value during deoptimization. /**
     * Excluding r27 is a temporary solution until we exclude r27 unconditionally at
     * {@link jdk.vm.ci.hotspot.aarch64.AArch64HotSpotRegisterConfig}.
     *
     * The underlying reason is that HotSpot does not intend to support r27 as an allocatable
     * register. This register is excluded from callee-saved register at
     * cpu/aarch64/sharedRuntime_aarch64.cpp:RegisterSaver::save_live_registers, and may lead to
     * dereferencing unknown value from the stack at
     * share/runtime/stackValue.cpp:StackValue::create_stack_value during deoptimization.
     */
    // @formatter:off
    static final Register[] registerAllocationOrder = {
        r0,  r1,  r2,  r3,  r4,  r5,  r6,  r7,
        r8,  r9,  r10, r11, r12, r13, r14, r15,
        r16, r17, r18, r19, r20, r21, r22, r23,
        r24, r25, r26, /* r27, */ r28, r29, r30, r31,

        v0,  v1,  v2,  v3,  v4,  v5,  v6,  v7,
        v8,  v9,  v10, v11, v12, v13, v14, v15,
        v16, v17, v18, v19, v20, v21, v22, v23,
        v24, v25, v26, v27, v28, v29, v30, v31
    };
    // @formatter:on

    public AArch64HotSpotRegisterAllocationConfig(RegisterConfig registerConfig, String[] allocationRestrictedTo) {
        super(registerConfig, allocationRestrictedTo);
    }

    @Override
    protected RegisterArray initAllocatable(RegisterArray registers) {
        BitSet regMap = new BitSet(registerConfig.getAllocatableRegisters().size());
        for (Register reg : registers) {
            regMap.set(reg.number);
        }

        ArrayList<Register> allocatableRegisters = new ArrayList<>(registers.size());
        for (Register reg : registerAllocationOrder) {
            if (regMap.get(reg.number)) {
                allocatableRegisters.add(reg);
            }
        }

        return super.initAllocatable(new RegisterArray(allocatableRegisters));
    }
}