1/*
2 * Copyright (c) 1994, 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
26package sun.tools.tree;
27
28import sun.tools.java.*;
29import sun.tools.asm.Assembler;
30import java.io.PrintStream;
31import java.util.Hashtable;
32
33/**
34 * WARNING: The contents of this source file are not part of any
35 * supported API.  Code that depends on them does so at its own risk:
36 * they are subject to change or removal without notice.
37 */
38public
39class AssignExpression extends BinaryAssignExpression {
40
41    private FieldUpdater updater = null;
42
43    /**
44     * Constructor
45     */
46    public AssignExpression(long where, Expression left, Expression right) {
47        super(ASSIGN, where, left, right);
48    }
49
50    /**
51     * Check an assignment expression
52     */
53    public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp) {
54        if (left instanceof IdentifierExpression) {
55            // we don't want to mark an identifier as having a value
56            // until having evaluated the right-hand side
57            vset = right.checkValue(env, ctx, vset, exp);
58            vset = left.checkLHS(env, ctx, vset, exp);
59        } else {
60            // normally left to right evaluation.
61            vset = left.checkLHS(env, ctx, vset, exp);
62            vset = right.checkValue(env, ctx, vset, exp);
63        }
64        type = left.type;
65        right = convert(env, ctx, type, right);
66
67        // Get field updater (access method) if needed, else null.
68        updater = left.getAssigner(env, ctx);
69
70        return vset;
71    }
72
73    /**
74     * Inline
75     */
76    public Expression inlineValue(Environment env, Context ctx) {
77        if (implementation != null)
78            return implementation.inlineValue(env, ctx);
79        // Must be 'inlineLHS' here.  But compare with similar case in
80        // 'AssignOpExpression' and 'IncDecExpression', which needs 'inlineValue'.
81        left = left.inlineLHS(env, ctx);
82        right = right.inlineValue(env, ctx);
83        if (updater != null) {
84            updater = updater.inline(env, ctx);
85        }
86        return this;
87    }
88
89    /**
90     * Create a copy of the expression for method inlining
91     */
92    public Expression copyInline(Context ctx) {
93        if (implementation != null)
94            return implementation.copyInline(ctx);
95        AssignExpression e = (AssignExpression)clone();
96        e.left = left.copyInline(ctx);
97        e.right = right.copyInline(ctx);
98        if (updater != null) {
99            e.updater = updater.copyInline(ctx);
100        }
101        return e;
102    }
103
104    /**
105     * The cost of inlining this expression
106     */
107    public int costInline(int thresh, Environment env, Context ctx) {
108        /*----------*
109        return 2 + super.costInline(thresh, env, ctx);
110        *----------*/
111        return (updater != null)
112            // Cost of rhs expression + cost of access method call.
113            // Access method call cost includes lhs cost.
114            ? right.costInline(thresh, env, ctx) +
115                  updater.costInline(thresh, env, ctx, false)
116            // Cost of rhs expression + cost of lhs expression +
117            // cost of store instruction.
118            : right.costInline(thresh, env, ctx) +
119                  left.costInline(thresh, env, ctx) + 2;
120    }
121
122    /**
123     * Code
124     */
125    public void codeValue(Environment env, Context ctx, Assembler asm) {
126        if (updater == null) {
127            // Field is directly accessible.
128            int depth = left.codeLValue(env, ctx, asm);
129            right.codeValue(env, ctx, asm);
130            codeDup(env, ctx, asm, right.type.stackSize(), depth);
131            left.codeStore(env, ctx, asm);
132        } else {
133            // Must use access method.
134            // Left operand is always a 'FieldExpression', or
135            // is rewritten as one via 'implementation'.
136            updater.startAssign(env, ctx, asm);
137            right.codeValue(env, ctx, asm);
138            updater.finishAssign(env, ctx, asm, true);
139        }
140    }
141
142    public void code(Environment env, Context ctx, Assembler asm) {
143        if (updater == null) {
144            // Field is directly accessible.
145            left.codeLValue(env, ctx, asm);
146            right.codeValue(env, ctx, asm);
147            left.codeStore(env, ctx, asm);
148        } else {
149            // Must use access method.
150            // Left operand is always a 'FieldExpression', or
151            // is rewritten as one via 'implementation'.
152            updater.startAssign(env, ctx, asm);
153            right.codeValue(env, ctx, asm);
154            updater.finishAssign(env, ctx, asm, false);
155        }
156    }
157}
158