/*
 * 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.stubs;

import static com.oracle.graal.hotspot.HotSpotGraalRuntime.*;
import static com.oracle.graal.hotspot.nodes.PatchReturnAddressNode.*;
import static com.oracle.graal.hotspot.replacements.HotSpotReplacementsUtil.*;
import static com.oracle.graal.hotspot.stubs.StubUtil.*;

import com.oracle.graal.api.code.RuntimeCallTarget.Descriptor;
import com.oracle.graal.api.code.*;
import com.oracle.graal.graph.Node.ConstantNodeParameter;
import com.oracle.graal.graph.Node.NodeIntrinsic;
import com.oracle.graal.hotspot.*;
import com.oracle.graal.hotspot.bridge.*;
import com.oracle.graal.hotspot.meta.*;
import com.oracle.graal.hotspot.nodes.*;
import com.oracle.graal.nodes.spi.*;
import com.oracle.graal.replacements.*;
import com.oracle.graal.replacements.Snippet.Fold;
import com.oracle.graal.word.*;

/**
 * Stub called by the {@linkplain Marks#MARK_EXCEPTION_HANDLER_ENTRY exception handler entry point}
 * in a compiled method. This entry point is used when returning to a method to handle an exception
 * thrown by a callee. It is not used for routing implicit exceptions. Therefore, it does not need
 * to save any registers as HotSpot uses a caller save convention.
 * <p>
 * The descriptor for a call to this stub is {@link HotSpotBackend#EXCEPTION_HANDLER}.
 */
public class ExceptionHandlerStub extends CRuntimeStub {

    public ExceptionHandlerStub(final HotSpotRuntime runtime, Replacements replacements, TargetDescription target, HotSpotRuntimeCallTarget linkage) {
        super(runtime, replacements, target, linkage);
    }

    /**
     * This stub is called when returning to a method to handle an exception thrown by a callee. It
     * is not used for routing implicit exceptions. Therefore, it does not need to save any
     * registers as HotSpot uses a caller save convention.
     */
    @Override
    public boolean preservesRegisters() {
        return false;
    }

    @Snippet
    private static void exceptionHandler(Object exception, Word exceptionPc) {
        checkNoExceptionInThread(assertionsEnabled());
        checkExceptionNotNull(assertionsEnabled(), exception);
        writeExceptionOop(thread(), exception);
        writeExceptionPc(thread(), exceptionPc);
        if (logging()) {
            printf("handling exception %p (", Word.fromObject(exception).rawValue());
            decipher(Word.fromObject(exception).rawValue());
            printf(") at %p (", exceptionPc.rawValue());
            decipher(exceptionPc.rawValue());
            printf(")\n");
        }

        // patch throwing pc into return address so that deoptimization finds the right debug info
        patchReturnAddress(exceptionPc);

        Word handlerPc = exceptionHandlerForPc(EXCEPTION_HANDLER_FOR_PC, thread());

        if (logging()) {
            printf("handler for exception %p at %p is at %p (", Word.fromObject(exception).rawValue(), exceptionPc.rawValue(), handlerPc.rawValue());
            decipher(handlerPc.rawValue());
            printf(")\n");
        }

        // patch the return address so that this stub returns to the exception handler
        patchReturnAddress(handlerPc);
    }

    static void checkNoExceptionInThread(boolean enabled) {
        if (enabled) {
            Object currentException = readExceptionOop(thread());
            if (currentException != null) {
                fatal("exception object in thread must be null, not %p", Word.fromObject(currentException).rawValue());
            }
            Word currentExceptionPc = readExceptionPc(thread());
            if (currentExceptionPc.notEqual(Word.zero())) {
                fatal("exception PC in thread must be zero, not %p", currentExceptionPc.rawValue());
            }
        }
    }

    static void checkExceptionNotNull(boolean enabled, Object exception) {
        if (enabled && exception == null) {
            fatal("exception must not be null");
        }
    }

    @Fold
    private static boolean logging() {
        return Boolean.getBoolean("graal.logExceptionHandlerStub");
    }

    @Fold
    @SuppressWarnings("all")
    private static boolean assertionsEnabled() {
        boolean enabled = false;
        assert enabled = true;
        return enabled || graalRuntime().getConfig().cAssertions;
    }

    public static final Descriptor EXCEPTION_HANDLER_FOR_PC = descriptorFor(ExceptionHandlerStub.class, "exceptionHandlerForPc", false);

    @NodeIntrinsic(value = CRuntimeCall.class, setStampFromReturnType = true)
    public static native Word exceptionHandlerForPc(@ConstantNodeParameter Descriptor exceptionHandlerForPc, Word thread);
}