hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.amd64/src/org/graalvm/compiler/core/amd64/AMD64MoveFactoryBase.java

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package org.graalvm.compiler.core.amd64;

import static org.graalvm.compiler.asm.amd64.AMD64Assembler.OperandSize.QWORD;
import static org.graalvm.compiler.asm.amd64.AMD64Assembler.OperandSize.WORD;

import java.util.HashMap;
import java.util.Map;

import org.graalvm.compiler.core.common.LIRKind;
import org.graalvm.compiler.lir.VirtualStackSlot;
import org.graalvm.compiler.lir.amd64.AMD64LIRInstruction;
import org.graalvm.compiler.lir.amd64.AMD64Move.AMD64PushPopStackMove;
import org.graalvm.compiler.lir.framemap.FrameMapBuilder;
import org.graalvm.compiler.lir.gen.LIRGeneratorTool.MoveFactory;

import jdk.vm.ci.amd64.AMD64Kind;
import jdk.vm.ci.code.Architecture;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.RegisterArray;
import jdk.vm.ci.code.RegisterConfig;
import jdk.vm.ci.meta.AllocatableValue;
import jdk.vm.ci.meta.PlatformKind;

public abstract class AMD64MoveFactoryBase implements MoveFactory {

    private final BackupSlotProvider backupSlotProvider;

    private static class RegisterBackupPair {
        public final Register register;
        public final VirtualStackSlot backupSlot;

        RegisterBackupPair(Register register, VirtualStackSlot backupSlot) {
            this.register = register;
            this.backupSlot = backupSlot;
        }
    }

    public static final class BackupSlotProvider {

        private final FrameMapBuilder frameMapBuilder;
        private Map<PlatformKind.Key, RegisterBackupPair> categorized;

        public BackupSlotProvider(FrameMapBuilder frameMapBuilder) {
            this.frameMapBuilder = frameMapBuilder;
        }

        protected RegisterBackupPair getScratchRegister(PlatformKind kind) {
            PlatformKind.Key key = kind.getKey();
            if (categorized == null) {
                categorized = new HashMap<>();
            } else if (categorized.containsKey(key)) {
                return categorized.get(key);
            }

            RegisterConfig registerConfig = frameMapBuilder.getRegisterConfig();

            RegisterArray availableRegister = registerConfig.filterAllocatableRegisters(kind, registerConfig.getAllocatableRegisters());
            assert availableRegister != null && availableRegister.size() > 1;
            Register scratchRegister = availableRegister.get(0);

            Architecture arch = frameMapBuilder.getCodeCache().getTarget().arch;
            LIRKind largestKind = LIRKind.value(arch.getLargestStorableKind(scratchRegister.getRegisterCategory()));
            VirtualStackSlot backupSlot = frameMapBuilder.allocateSpillSlot(largestKind);

            RegisterBackupPair value = new RegisterBackupPair(scratchRegister, backupSlot);
            categorized.put(key, value);

            return value;
        }
    }

    public AMD64MoveFactoryBase(BackupSlotProvider backupSlotProvider) {
        this.backupSlotProvider = backupSlotProvider;
    }

    @Override
    public final AMD64LIRInstruction createStackMove(AllocatableValue result, AllocatableValue input) {
        AMD64Kind kind = (AMD64Kind) result.getPlatformKind();
        switch (kind.getSizeInBytes()) {
            case 2:
                return new AMD64PushPopStackMove(WORD, result, input);
            case 8:
                return new AMD64PushPopStackMove(QWORD, result, input);
            default:
                RegisterBackupPair backup = backupSlotProvider.getScratchRegister(input.getPlatformKind());
                Register scratchRegister = backup.register;
                VirtualStackSlot backupSlot = backup.backupSlot;
                return createStackMove(result, input, scratchRegister, backupSlot);
        }
    }

    public abstract AMD64LIRInstruction createStackMove(AllocatableValue result, AllocatableValue input, Register scratchRegister, AllocatableValue backupSlot);
}