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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 2003, 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.tools.tree; | ||
| 27 | |||
| 28 | import sun.tools.java.*; | ||
| 29 | import sun.tools.asm.Assembler; | ||
| 30 | import java.io.PrintStream; | ||
| 31 | |||
| 32 | /** | ||
| 33 | * This class encapsulates the information required to generate an update to a private | ||
| 34 | * field referenced from another class, e.g., an inner class. An expression denoting a | ||
| 35 | * reference to the object to which the field belongs is associated with getter and | ||
| 36 | * setter methods. | ||
| 37 | * <p> | ||
| 38 | * We use this class only for assignment, increment, and decrement operators, in which | ||
| 39 | * the old value is first retrieved and then a new value is computed and stored. | ||
| 40 | * Simple assignment expressions in which a value is copied without modification are | ||
| 41 | * handled by another mechanism. | ||
| 42 | * | ||
| 43 | * WARNING: The contents of this source file are not part of any | ||
| 44 | * supported API. Code that depends on them does so at its own risk: | ||
| 45 | * they are subject to change or removal without notice. | ||
| 46 | */ | ||
| 47 | |||
| 48 | class FieldUpdater implements Constants { | ||
| 49 | |||
| 50 | // Location for reporting errors. | ||
| 51 | // Errors will always indicate compiler failure, but these will be easier to diagnose | ||
| 52 | // if the bogus error is localized to the offending assignment. | ||
| 53 | private long where; | ||
| 54 | |||
| 55 | // The field to which this updater applies. | ||
| 56 | // It would be easy to eliminate the need to store the field here, but we retain it for | ||
| 57 | // diagnostic purposes. | ||
| 58 | private MemberDefinition field; | ||
| 59 | |||
| 60 | // Expression denoting the object to which the getter and setter are applied. | ||
| 61 | // If the field is static, 'base' may be null, but need not be, as a static field | ||
| 62 | // may be selected from an object reference. Even though the value of the object | ||
| 63 | // reference will be ignored, it may have side-effects. | ||
| 64 | private Expression base; | ||
| 65 | |||
| 66 | // The getter and setter methods, generated by 'getAccessMember' and 'getUpdateMember'. | ||
| 67 | private MemberDefinition getter; | ||
| 68 | private MemberDefinition setter; | ||
| 69 | |||
| 70 | // The number of words occupied on the stack by the object reference. | ||
| 71 | // For static fields, this is zero. | ||
| 72 | private int depth; | ||
| 73 | |||
| 74 | /** | ||
| 75 | * Constructor. | ||
| 76 | */ | ||
| 77 | |||
| 78 | public FieldUpdater(long where, MemberDefinition field, | ||
| 79 | Expression base, MemberDefinition getter, MemberDefinition setter) { | ||
| 80 | this.where = where; | ||
| 81 | this.field = field; | ||
| 82 | this.base = base; | ||
| 83 | this.getter = getter; | ||
| 84 | this.setter = setter; | ||
| 85 | } | ||
| 86 | |||
| 87 | |||
| 88 | /** | ||
| 89 | * Since the object reference expression may be captured before it has been inlined, | ||
| 90 | * we must inline it later. A <code>FieldUpdater</code> is inlined essentially as if | ||
| 91 | * it were a child of the assignment node to which it belongs. | ||
| 92 | */ | ||
| 93 | |||
| 94 | public FieldUpdater inline(Environment env, Context ctx) { | ||
| 95 | if (base != null) { | ||
| 96 | if (field.isStatic()) { | ||
| 97 | base = base.inline(env, ctx); | ||
| 98 | } else { | ||
| 99 | base = base.inlineValue(env, ctx); | ||
| 100 | } | ||
| 101 | } | ||
| 102 | return this; | ||
| 103 | } | ||
| 104 | |||
| 105 | public FieldUpdater copyInline(Context ctx) { | ||
| 106 | return new FieldUpdater(where, field, base.copyInline(ctx), getter, setter); | ||
| 107 | } | ||
| 108 | |||
| 109 | public int costInline(int thresh, Environment env, Context ctx, boolean needGet) { | ||
| 110 | // Size of 'invokestatic' call for access method is 3 bytes. | ||
| 111 | int cost = needGet ? 7 : 3; // getter needs extra invokestatic + dup | ||
| 112 | // Size of expression to compute 'this' arg if needed. | ||
| 113 | if (!field.isStatic() && base != null) { | ||
| 114 | cost += base.costInline(thresh, env, ctx); | ||
| 115 | } | ||
| 116 | // We ignore the cost of duplicating value in value-needed context. | ||
| 117 | return cost; | ||
| 118 | } | ||
| 119 | |||
| 120 | /** | ||
| 121 | * Duplicate <code>items</code> words from the top of the stack, locating them | ||
| 122 | * below the topmost <code>depth</code> words on the stack. | ||
| 123 | */ | ||
| 124 | |||
| 125 | // This code was cribbed from 'Expression.java'. We cannot reuse that code here, | ||
| 126 | // because we do not inherit from class 'Expression'. | ||
| 127 | |||
| 128 | private void codeDup(Assembler asm, int items, int depth) { | ||
| 129 | switch (items) { | ||
| 130 | case 0: | ||
| 131 | return; | ||
| 132 | case 1: | ||
| 133 | switch (depth) { | ||
| 134 | case 0: | ||
| 135 | asm.add(where, opc_dup); | ||
| 136 | return; | ||
| 137 | case 1: | ||
| 138 | asm.add(where, opc_dup_x1); | ||
| 139 | return; | ||
| 140 | case 2: | ||
| 141 | asm.add(where, opc_dup_x2); | ||
| 142 | return; | ||
| 143 | |||
| 144 | } | ||
| 145 | break; | ||
| 146 | case 2: | ||
| 147 | switch (depth) { | ||
| 148 | case 0: | ||
| 149 | asm.add(where, opc_dup2); | ||
| 150 | return; | ||
| 151 | case 1: | ||
| 152 | asm.add(where, opc_dup2_x1); | ||
| 153 | return; | ||
| 154 | case 2: | ||
| 155 | asm.add(where, opc_dup2_x2); | ||
| 156 | return; | ||
| 157 | |||
| 158 | } | ||
| 159 | break; | ||
| 160 | } | ||
| 161 | throw new CompilerError("can't dup: " + items + ", " + depth); | ||
| 162 | } | ||
| 163 | |||
| 164 | /** | ||
| 165 | * Begin a field update by an assignment, increment, or decrement operator. | ||
| 166 | * The current value of the field is left at the top of the stack. | ||
| 167 | * If <code>valNeeded</code> is true, we arrange for the initial value to remain | ||
| 168 | * on the stack after the update. | ||
| 169 | */ | ||
| 170 | |||
| 171 | public void startUpdate(Environment env, Context ctx, Assembler asm, boolean valNeeded) { | ||
| 172 | if (!(getter.isStatic() && setter.isStatic())) { | ||
| 173 | throw new CompilerError("startUpdate isStatic"); | ||
| 174 | } | ||
| 175 | if (!field.isStatic()) { | ||
| 176 | // Provide explicit 'this' argument. | ||
| 177 | base.codeValue(env, ctx, asm); | ||
| 178 | depth = 1; | ||
| 179 | } else { | ||
| 180 | // May need to evaluate 'base' for effect. | ||
| 181 | // If 'base' was a type expression, it should have previously been inlined away. | ||
| 182 | if (base != null) { | ||
| 183 | base.code(env, ctx, asm); | ||
| 184 | } | ||
| 185 | depth = 0; | ||
| 186 | } | ||
| 187 | codeDup(asm, depth, 0); | ||
| 188 | asm.add(where, opc_invokestatic, getter); | ||
| 189 | if (valNeeded) { | ||
| 190 | codeDup(asm, field.getType().stackSize(), depth); | ||
| 191 | } | ||
| 192 | } | ||
| 193 | |||
| 194 | /** | ||
| 195 | * Complete a field update by an assignment, increment, or decrement operator. | ||
| 196 | * The original value of the field left on the stack by <code>startUpdate</code> | ||
| 197 | * must have been replaced with the updated value, with no other stack alterations. | ||
| 198 | * If <code>valNeeded</code> is true, we arrange for the updated value to remain | ||
| 199 | * on the stack after the update. The <code>valNeeded</code> argument must not be | ||
| 200 | * true in both <code>startUpdate</code> and <code>finishUpdate</code>. | ||
| 201 | */ | ||
| 202 | |||
| 203 | public void finishUpdate(Environment env, Context ctx, Assembler asm, boolean valNeeded) { | ||
| 204 | if (valNeeded) { | ||
| 205 | codeDup(asm, field.getType().stackSize(), depth); | ||
| 206 | } | ||
| 207 | asm.add(where, opc_invokestatic, setter); | ||
| 208 | } | ||
| 209 | |||
| 210 | /** | ||
| 211 | * Like above, but used when assigning a new value independent of the | ||
| 212 | * old, as in a simple assignment expression. After 'startAssign', | ||
| 213 | * code must be emitted to leave one additional value on the stack without | ||
| 214 | * altering any others, followed by 'finishAssign'. | ||
| 215 | */ | ||
| 216 | |||
| 217 | public void startAssign(Environment env, Context ctx, Assembler asm) { | ||
| 218 | if (!setter.isStatic()) { | ||
| 219 | throw new CompilerError("startAssign isStatic"); | ||
| 220 | } | ||
| 221 | if (!field.isStatic()) { | ||
| 222 | // Provide explicit 'this' argument. | ||
| 223 | base.codeValue(env, ctx, asm); | ||
| 224 | depth = 1; | ||
| 225 | } else { | ||
| 226 | // May need to evaluate 'base' for effect. | ||
| 227 | // If 'base' was a type expression, it should have previously been inlined away. | ||
| 228 | if (base != null) { | ||
| 229 | base.code(env, ctx, asm); | ||
| 230 | } | ||
| 231 | depth = 0; | ||
| 232 | } | ||
| 233 | } | ||
| 234 | |||
| 235 | public void finishAssign(Environment env, Context ctx, Assembler asm, boolean valNeeded) { | ||
| 236 | if (valNeeded) { | ||
| 237 | codeDup(asm, field.getType().stackSize(), depth); | ||
| 238 | } | ||
| 239 | asm.add(where, opc_invokestatic, setter); | ||
| 240 | } | ||
| 241 | |||
| 242 | } | ||