/*
 * Copyright (c) 2012, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.graal.hotspot;

import java.util.*;

import com.oracle.graal.api.code.*;
import com.oracle.graal.api.meta.*;
import com.oracle.graal.compiler.target.*;
import com.oracle.graal.hotspot.bridge.*;
import com.oracle.graal.hotspot.stubs.*;

/**
 * The details required to link a HotSpot runtime or stub call.
 */
public class HotSpotRuntimeCallTarget implements RuntimeCallTarget, InvokeTarget {

    /**
     * The descriptor of the stub. This is for informational purposes only.
     */
    public final Descriptor descriptor;

    /**
     * The entry point address of the stub.
     */
    private long address;

    /**
     * Non-null (eventually) iff this is a call to a compiled {@linkplain Stub stub}.
     */
    private Stub stub;

    /**
     * Where the stub gets its arguments and where it places its result.
     */
    private CallingConvention cc;

    private final CompilerToVM vm;

    private final boolean isCRuntimeCall;

    public HotSpotRuntimeCallTarget(Descriptor descriptor, long address, boolean isCRuntimeCall, CallingConvention cc, CompilerToVM vm) {
        this.address = address;
        this.isCRuntimeCall = isCRuntimeCall;
        this.descriptor = descriptor;
        this.cc = cc;
        this.vm = vm;
    }

    @Override
    public String toString() {
        return (stub == null ? descriptor.toString() : MetaUtil.format("%h.%n", stub.getMethod())) + "@0x" + Long.toHexString(address) + ":" + cc;
    }

    public CallingConvention getCallingConvention() {
        return cc;
    }

    public long getMaxCallTargetOffset() {
        return vm.getMaxCallTargetOffset(address);
    }

    public Descriptor getDescriptor() {
        return descriptor;
    }

    public void setStub(Stub stub) {
        assert address == 0L : "cannot set stub for linkage that already has an address: " + this;
        this.stub = stub;
    }

    public void finalizeAddress(Backend backend) {
        if (address == 0) {
            assert stub != null : "linkage without an address must be a stub - forgot to register a Stub associated with " + descriptor + "?";
            InstalledCode code = stub.getCode(backend);

            AllocatableValue[] argumentLocations = new AllocatableValue[cc.getArgumentCount()];
            for (int i = 0; i < argumentLocations.length; i++) {
                argumentLocations[i] = cc.getArgument(i);
            }

            Set<Register> destroyedRegisters = stub.getDestroyedRegisters();
            AllocatableValue[] temporaryLocations = new AllocatableValue[destroyedRegisters.size()];
            int i = 0;
            for (Register reg : destroyedRegisters) {
                temporaryLocations[i++] = reg.asValue();
            }
            // Update calling convention with temporaries
            cc = new CallingConvention(temporaryLocations, cc.getStackSize(), cc.getReturn(), argumentLocations);
            address = code.getStart();
        }
    }

    public long getAddress() {
        assert address != 0L : "address not yet finalized: " + this;
        return address;
    }

    @Override
    public boolean destroysRegisters() {
        if (isCRuntimeCall) {
            // Even though most native ABIs define some callee saved registers,
            // for simplicity we force the register allocator to save all live
            // registers across a C runtime call as such calls are only made from
            // compiled stubs which a) are slow path and b) will typically only
            // have very few live registers across a C runtime call
            return true;
        }
        // This is a call to a compiled (or assembler) stub which saves
        // all registers (apart from its temporaries)
        return false;
    }

    /**
     * Determines if this is a link to a C/C++ function in the HotSpot runtime.
     */
    public boolean isCRuntimeCall() {
        return isCRuntimeCall;
    }
}