JDK8/Java8源码在线阅读

/*
 * Copyright (c) 1994, 2003, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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 sun.tools.tree;

import sun.tools.java.*;
import sun.tools.asm.Assembler;
import sun.tools.asm.Label;
import sun.tools.asm.TryData;
import sun.tools.asm.CatchData;
import java.io.PrintStream;
import java.util.Hashtable;

/**
 * WARNING: The contents of this source file are not part of any
 * supported API.  Code that depends on them does so at its own risk:
 * they are subject to change or removal without notice.
 */
public
class SynchronizedStatement extends Statement {
    Expression expr;
    Statement body;
    boolean needReturnSlot;   // set by inner return statement

    /**
     * Constructor
     */
    public SynchronizedStatement(long where, Expression expr, Statement body) {
        super(SYNCHRONIZED, where);
        this.expr = expr;
        this.body = body;
    }

    /**
     * Check statement
     */
    Vset check(Environment env, Context ctx, Vset vset, Hashtable exp) {
        checkLabel(env, ctx);
        CheckContext newctx = new CheckContext(ctx, this);
        vset = reach(env, vset);
        vset = expr.checkValue(env, newctx, vset, exp);
        if (expr.type.equals(Type.tNull)) {
            env.error(expr.where, "synchronized.null");
        }
        expr = convert(env, newctx, Type.tClass(idJavaLangObject), expr);
        vset = body.check(env, newctx, vset, exp);
        return ctx.removeAdditionalVars(vset.join(newctx.vsBreak));
    }

    /**
     * Inline
     */
    public Statement inline(Environment env, Context ctx) {
        if (body != null) {
            body = body.inline(env, ctx);
        }
        expr = expr.inlineValue(env, ctx);
        return this;
    }

    /**
     * Create a copy of the statement for method inlining
     */
    public Statement copyInline(Context ctx, boolean valNeeded) {
        SynchronizedStatement s = (SynchronizedStatement)clone();
        s.expr = expr.copyInline(ctx);
        if (body != null) {
            s.body = body.copyInline(ctx, valNeeded);
        }
        return s;
    }

    /**
     * Compute cost of inlining this statement
     */
    public int costInline(int thresh, Environment env, Context ctx){
        int cost = 1;
        if (expr != null) {
            cost += expr.costInline(thresh, env,ctx);
            if (cost >= thresh) return cost;
        }
        if (body != null) {
            cost += body.costInline(thresh, env,ctx);
        }
        return cost;
    }

    /**
     * Code
     */
    public void code(Environment env, Context ctx, Assembler asm) {
        ClassDefinition clazz = ctx.field.getClassDefinition();
        expr.codeValue(env, ctx, asm);
        ctx = new Context(ctx);

        if (needReturnSlot) {
            Type returnType = ctx.field.getType().getReturnType();
            LocalMember localfield = new LocalMember(0, clazz, 0, returnType,
                                                   idFinallyReturnValue);
            ctx.declare(env, localfield);
            env.debugOutput("Assigning return slot to " + localfield.number);
        }

        LocalMember f1 = new LocalMember(where, clazz, 0, Type.tObject, null);
        LocalMember f2 = new LocalMember(where, clazz, 0, Type.tInt, null);
        Integer num1 = new Integer(ctx.declare(env, f1));
        Integer num2 = new Integer(ctx.declare(env, f2));

        Label endLabel = new Label();

        TryData td = new TryData();
        td.add(null);

        // lock the object
        asm.add(where, opc_astore, num1);
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorenter);

        // Main body
        CodeContext bodyctx = new CodeContext(ctx, this);
        asm.add(where, opc_try, td);
        if (body != null) {
            body.code(env, bodyctx, asm);
        } else {
            asm.add(where, opc_nop);
        }
        asm.add(bodyctx.breakLabel);
        asm.add(td.getEndLabel());

        // Cleanup afer body
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorexit);
        asm.add(where, opc_goto, endLabel);

        // Catch code
        CatchData cd = td.getCatch(0);
        asm.add(cd.getLabel());
        asm.add(where, opc_aload, num1);
        asm.add(where, opc_monitorexit);

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