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 * Copyright (c) 2013, 2015, 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

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package org.graalvm.compiler.lir.amd64;

import static jdk.vm.ci.code.ValueUtil.asStackSlot;

import static jdk.vm.ci.code.ValueUtil.isStackSlot;

import java.util.Arrays;

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

import org.graalvm.compiler.lir.LIRInstructionClass;

import org.graalvm.compiler.lir.LIRValueUtil;

import org.graalvm.compiler.lir.Opcode;

import org.graalvm.compiler.lir.StandardOp.SaveRegistersOp;

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

import org.graalvm.compiler.lir.framemap.FrameMap;

import jdk.vm.ci.amd64.AMD64Kind;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.code.RegisterSaveLayout;

import jdk.vm.ci.code.StackSlot;

import jdk.vm.ci.meta.AllocatableValue;

/**

 * Saves registers to stack slots.

 */

@Opcode("SAVE_REGISTER")

public class AMD64SaveRegistersOp extends AMD64LIRInstruction implements SaveRegistersOp {

    public static final LIRInstructionClass<AMD64SaveRegistersOp> TYPE = LIRInstructionClass.create(AMD64SaveRegistersOp.class);

    /**

     * The registers (potentially) saved by this operation.

     */

    protected final Register[] savedRegisters;

    /**

     * The slots to which the registers are saved.

     */

    @Def(STACK) protected final AllocatableValue[] slots;

    /**

     * Specifies if {@link #remove(EconomicSet)} should have an effect.

     */

    protected final boolean supportsRemove;

    /**

     *

     * @param savedRegisters the registers saved by this operation which may be subject to

     *            {@linkplain #remove(EconomicSet) pruning}

     * @param savedRegisterLocations the slots to which the registers are saved

     * @param supportsRemove determines if registers can be {@linkplain #remove(EconomicSet) pruned}

     */

    public AMD64SaveRegistersOp(Register[] savedRegisters, AllocatableValue[] savedRegisterLocations, boolean supportsRemove) {

        this(TYPE, savedRegisters, savedRegisterLocations, supportsRemove);

    }

    public AMD64SaveRegistersOp(LIRInstructionClass<? extends AMD64SaveRegistersOp> c, Register[] savedRegisters, AllocatableValue[] savedRegisterLocations, boolean supportsRemove) {

        super(c);

        assert Arrays.asList(savedRegisterLocations).stream().allMatch(LIRValueUtil::isVirtualStackSlot);

        this.savedRegisters = savedRegisters;

        this.slots = savedRegisterLocations;

        this.supportsRemove = supportsRemove;

    }

    protected void saveRegister(CompilationResultBuilder crb, AMD64MacroAssembler masm, StackSlot result, Register input) {

        AMD64Move.reg2stack((AMD64Kind) result.getPlatformKind(), crb, masm, result, input);

    }

    @Override

    public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

        for (int i = 0; i < savedRegisters.length; i++) {

            if (savedRegisters[i] != null) {

                assert isStackSlot(slots[i]) : "not a StackSlot: " + slots[i];

                saveRegister(crb, masm, asStackSlot(slots[i]), savedRegisters[i]);

            }

        }

    }

    public AllocatableValue[] getSlots() {

        return slots;

    }

    @Override

    public boolean supportsRemove() {

        return supportsRemove;

    }

    @Override

    public int remove(EconomicSet<Register> doNotSave) {

        if (!supportsRemove) {

            throw new UnsupportedOperationException();

        }

        return prune(doNotSave, savedRegisters);

    }

    static int prune(EconomicSet<Register> toRemove, Register[] registers) {

        int pruned = 0;

        for (int i = 0; i < registers.length; i++) {

            if (registers[i] != null) {

                if (toRemove.contains(registers[i])) {

                    registers[i] = null;

                    pruned++;

                }

            }

        }

        return pruned;

    }

    @Override

    public RegisterSaveLayout getMap(FrameMap frameMap) {

        int total = 0;

        for (int i = 0; i < savedRegisters.length; i++) {

            if (savedRegisters[i] != null) {

                total++;

            }

        }

        Register[] keys = new Register[total];

        int[] values = new int[total];

        if (total != 0) {

            int mapIndex = 0;

            for (int i = 0; i < savedRegisters.length; i++) {

                if (savedRegisters[i] != null) {

                    keys[mapIndex] = savedRegisters[i];

                    assert isStackSlot(slots[i]) : "not a StackSlot: " + slots[i];

                    StackSlot slot = asStackSlot(slots[i]);

                    values[mapIndex] = indexForStackSlot(frameMap, slot);

                    mapIndex++;

                }

            }

            assert mapIndex == total;

        }

        return new RegisterSaveLayout(keys, values);

    }

    /**

     * Computes the index of a stack slot relative to slot 0. This is also the bit index of stack

     * slots in the reference map.

     *

     * @param slot a stack slot

     * @return the index of the stack slot

     */

    private static int indexForStackSlot(FrameMap frameMap, StackSlot slot) {

        assert frameMap.offsetForStackSlot(slot) % frameMap.getTarget().wordSize == 0;

        int value = frameMap.offsetForStackSlot(slot) / frameMap.getTarget().wordSize;

        return value;

    }

}