| /* |
| * Copyright (c) 1997, 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 java.io.PrintStream; |
| |
| /** |
| * This class encapsulates the information required to generate an update to a private |
| * field referenced from another class, e.g., an inner class. An expression denoting a |
| * reference to the object to which the field belongs is associated with getter and |
| * setter methods. |
| * <p> |
| * We use this class only for assignment, increment, and decrement operators, in which |
| * the old value is first retrieved and then a new value is computed and stored. |
| * Simple assignment expressions in which a value is copied without modification are |
| * handled by another mechanism. |
| * |
| * 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. |
| */ |
| |
| class FieldUpdater implements Constants { |
| |
| // Location for reporting errors. |
| // Errors will always indicate compiler failure, but these will be easier to diagnose |
| // if the bogus error is localized to the offending assignment. |
| private long where; |
| |
| // The field to which this updater applies. |
| // It would be easy to eliminate the need to store the field here, but we retain it for |
| // diagnostic purposes. |
| private MemberDefinition field; |
| |
| // Expression denoting the object to which the getter and setter are applied. |
| // If the field is static, 'base' may be null, but need not be, as a static field |
| // may be selected from an object reference. Even though the value of the object |
| // reference will be ignored, it may have side-effects. |
| private Expression base; |
| |
| // The getter and setter methods, generated by 'getAccessMember' and 'getUpdateMember'. |
| private MemberDefinition getter; |
| private MemberDefinition setter; |
| |
| // The number of words occupied on the stack by the object reference. |
| // For static fields, this is zero. |
| private int depth; |
| |
| /** |
| * Constructor. |
| */ |
| |
| public FieldUpdater(long where, MemberDefinition field, |
| Expression base, MemberDefinition getter, MemberDefinition setter) { |
| this.where = where; |
| this.field = field; |
| this.base = base; |
| this.getter = getter; |
| this.setter = setter; |
| } |
| |
| |
| /** |
| * Since the object reference expression may be captured before it has been inlined, |
| * we must inline it later. A <code>FieldUpdater</code> is inlined essentially as if |
| * it were a child of the assignment node to which it belongs. |
| */ |
| |
| public FieldUpdater inline(Environment env, Context ctx) { |
| if (base != null) { |
| if (field.isStatic()) { |
| base = base.inline(env, ctx); |
| } else { |
| base = base.inlineValue(env, ctx); |
| } |
| } |
| return this; |
| } |
| |
| public FieldUpdater copyInline(Context ctx) { |
| return new FieldUpdater(where, field, base.copyInline(ctx), getter, setter); |
| } |
| |
| public int costInline(int thresh, Environment env, Context ctx, boolean needGet) { |
| // Size of 'invokestatic' call for access method is 3 bytes. |
| int cost = needGet ? 7 : 3; // getter needs extra invokestatic + dup |
| // Size of expression to compute 'this' arg if needed. |
| if (!field.isStatic() && base != null) { |
| cost += base.costInline(thresh, env, ctx); |
| } |
| // We ignore the cost of duplicating value in value-needed context. |
| return cost; |
| } |
| |
| /** |
| * Duplicate <code>items</code> words from the top of the stack, locating them |
| * below the topmost <code>depth</code> words on the stack. |
| */ |
| |
| // This code was cribbed from 'Expression.java'. We cannot reuse that code here, |
| // because we do not inherit from class 'Expression'. |
| |
| private void codeDup(Assembler asm, int items, int depth) { |
| switch (items) { |
| case 0: |
| return; |
| case 1: |
| switch (depth) { |
| case 0: |
| asm.add(where, opc_dup); |
| return; |
| case 1: |
| asm.add(where, opc_dup_x1); |
| return; |
| case 2: |
| asm.add(where, opc_dup_x2); |
| return; |
| |
| } |
| break; |
| case 2: |
| switch (depth) { |
| case 0: |
| asm.add(where, opc_dup2); |
| return; |
| case 1: |
| asm.add(where, opc_dup2_x1); |
| return; |
| case 2: |
| asm.add(where, opc_dup2_x2); |
| return; |
| |
| } |
| break; |
| } |
| throw new CompilerError("can't dup: " + items + ", " + depth); |
| } |
| |
| /** |
| * Begin a field update by an assignment, increment, or decrement operator. |
| * The current value of the field is left at the top of the stack. |
| * If <code>valNeeded</code> is true, we arrange for the initial value to remain |
| * on the stack after the update. |
| */ |
| |
| public void startUpdate(Environment env, Context ctx, Assembler asm, boolean valNeeded) { |
| if (!(getter.isStatic() && setter.isStatic())) { |
| throw new CompilerError("startUpdate isStatic"); |
| } |
| if (!field.isStatic()) { |
| // Provide explicit 'this' argument. |
| base.codeValue(env, ctx, asm); |
| depth = 1; |
| } else { |
| // May need to evaluate 'base' for effect. |
| // If 'base' was a type expression, it should have previously been inlined away. |
| if (base != null) { |
| base.code(env, ctx, asm); |
| } |
| depth = 0; |
| } |
| codeDup(asm, depth, 0); |
| asm.add(where, opc_invokestatic, getter); |
| if (valNeeded) { |
| codeDup(asm, field.getType().stackSize(), depth); |
| } |
| } |
| |
| /** |
| * Complete a field update by an assignment, increment, or decrement operator. |
| * The original value of the field left on the stack by <code>startUpdate</code> |
| * must have been replaced with the updated value, with no other stack alterations. |
| * If <code>valNeeded</code> is true, we arrange for the updated value to remain |
| * on the stack after the update. The <code>valNeeded</code> argument must not be |
| * true in both <code>startUpdate</code> and <code>finishUpdate</code>. |
| */ |
| |
| public void finishUpdate(Environment env, Context ctx, Assembler asm, boolean valNeeded) { |
| if (valNeeded) { |
| codeDup(asm, field.getType().stackSize(), depth); |
| } |
| asm.add(where, opc_invokestatic, setter); |
| } |
| |
| /** |
| * Like above, but used when assigning a new value independent of the |
| * old, as in a simple assignment expression. After 'startAssign', |
| * code must be emitted to leave one additional value on the stack without |
| * altering any others, followed by 'finishAssign'. |
| */ |
| |
| public void startAssign(Environment env, Context ctx, Assembler asm) { |
| if (!setter.isStatic()) { |
| throw new CompilerError("startAssign isStatic"); |
| } |
| if (!field.isStatic()) { |
| // Provide explicit 'this' argument. |
| base.codeValue(env, ctx, asm); |
| depth = 1; |
| } else { |
| // May need to evaluate 'base' for effect. |
| // If 'base' was a type expression, it should have previously been inlined away. |
| if (base != null) { |
| base.code(env, ctx, asm); |
| } |
| depth = 0; |
| } |
| } |
| |
| public void finishAssign(Environment env, Context ctx, Assembler asm, boolean valNeeded) { |
| if (valNeeded) { |
| codeDup(asm, field.getType().stackSize(), depth); |
| } |
| asm.add(where, opc_invokestatic, setter); |
| } |
| |
| } |