1 /*

     2  * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package sun.reflect;

    27 

    28 import java.util.List;

    29 import java.util.ArrayList;

    30 

    31 /** Allows forward references in bytecode streams emitted by

    32     ClassFileAssembler. Assumes that the start of the method body is

    33     the first byte in the assembler's buffer. May be used at more than

    34     one branch site. */

    35 

    36 class Label {

    37     static class PatchInfo {

    38         PatchInfo(ClassFileAssembler asm,

    39                   short instrBCI,

    40                   short patchBCI,

    41                   int stackDepth)

    42         {

    43             this.asm = asm;

    44             this.instrBCI   = instrBCI;

    45             this.patchBCI   = patchBCI;

    46             this.stackDepth = stackDepth;

    47         }

    48         // This won't work for more than one assembler anyway, so this is

    49         // unnecessary

    50         final ClassFileAssembler asm;

    51         final short instrBCI;

    52         final short patchBCI;

    53         final int   stackDepth;

    54     }

    55     private final List<PatchInfo> patches = new ArrayList<>();

    56 

    57     public Label() {

    58     }

    59 

    60     void add(ClassFileAssembler asm,

    61              short instrBCI,

    62              short patchBCI,

    63              int stackDepth)

    64     {

    65         patches.add(new PatchInfo(asm, instrBCI, patchBCI, stackDepth));

    66     }

    67 

    68     public void bind() {

    69         for (PatchInfo patch : patches){

    70             short curBCI = patch.asm.getLength();

    71             short offset = (short) (curBCI - patch.instrBCI);

    72             patch.asm.emitShort(patch.patchBCI, offset);

    73             patch.asm.setStack(patch.stackDepth);

    74         }

    75     }

    76 }