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25 
26 package sun.tools.tree;
27 
28 import sun.tools.java.*;
29 import sun.tools.asm.Assembler;
30 import java.util.Hashtable;
31 
32 /**
33  * WARNING: The contents of this source file are not part of any
34  * supported API.  Code that depends on them does so at its own risk:
35  * they are subject to change or removal without notice.
36  */
37 public
38 class IncDecExpression extends UnaryExpression {
39 
40     private FieldUpdater updater = null;
41 
42     /**
43      * Constructor
44      */
IncDecExpression(int op, long where, Expression right)45     public IncDecExpression(int op, long where, Expression right) {
46         super(op, where, right.type, right);
47     }
48 
49     /**
50      * Check an increment or decrement expression
51      */
checkValue(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp)52     public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp) {
53         vset = right.checkAssignOp(env, ctx, vset, exp, this);
54         if (right.type.inMask(TM_NUMBER)) {
55             type = right.type;
56         } else {
57             if (!right.type.isType(TC_ERROR)) {
58                 env.error(where, "invalid.arg.type", right.type, opNames[op]);
59             }
60             type = Type.tError;
61         }
62         updater = right.getUpdater(env, ctx);  // Must be called after 'checkAssignOp'.
63         return vset;
64     }
65 
66     /**
67      * Check void expression
68      */
check(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp)69     public Vset check(Environment env, Context ctx, Vset vset, Hashtable<Object, Object> exp) {
70         return checkValue(env, ctx, vset, exp);
71     }
72 
73     /**
74      * Inline
75      */
inline(Environment env, Context ctx)76     public Expression inline(Environment env, Context ctx) {
77         return inlineValue(env, ctx);
78     }
inlineValue(Environment env, Context ctx)79     public Expression inlineValue(Environment env, Context ctx) {
80         // Why not inlineLHS?  But that does not work.
81         right = right.inlineValue(env, ctx);
82         if (updater != null) {
83             updater = updater.inline(env, ctx);
84         }
85         return this;
86     }
87 
costInline(int thresh, Environment env, Context ctx)88     public int costInline(int thresh, Environment env, Context ctx) {
89         if (updater == null) {
90             if ((right.op == IDENT) && type.isType(TC_INT) &&
91                 (((IdentifierExpression)right).field.isLocal())) {
92                 // Increment variable in place.  Count 3 bytes for 'iinc'.
93                 return 3;
94             }
95             // Cost to load lhs reference, fetch local, increment, and store.
96             // Load/store cost will be higher if variable is a field.  Note that
97             // costs are highly approximate. See 'AssignOpExpression.costInline'
98             // Does not account for cost of conversions,or duplications in
99             // value-needed context..
100             return right.costInline(thresh, env, ctx) + 4;
101         } else {
102             // Cost of two access method calls (get/set) + cost of increment.
103             return updater.costInline(thresh, env, ctx, true) + 1;
104         }
105     }
106 
107 
108     /**
109      * Code
110      */
111 
codeIncDecOp(Assembler asm, boolean inc)112     private void codeIncDecOp(Assembler asm, boolean inc) {
113         switch (type.getTypeCode()) {
114           case TC_BYTE:
115             asm.add(where, opc_ldc, 1);
116             asm.add(where, inc ? opc_iadd : opc_isub);
117             asm.add(where, opc_i2b);
118             break;
119           case TC_SHORT:
120             asm.add(where, opc_ldc, 1);
121             asm.add(where, inc ? opc_iadd : opc_isub);
122             asm.add(where, opc_i2s);
123             break;
124           case TC_CHAR:
125             asm.add(where, opc_ldc, 1);
126             asm.add(where, inc ? opc_iadd : opc_isub);
127             asm.add(where, opc_i2c);
128             break;
129           case TC_INT:
130             asm.add(where, opc_ldc, 1);
131             asm.add(where, inc ? opc_iadd : opc_isub);
132             break;
133           case TC_LONG:
134             asm.add(where, opc_ldc2_w, 1L);
135             asm.add(where, inc ? opc_ladd : opc_lsub);
136             break;
137           case TC_FLOAT:
138             asm.add(where, opc_ldc, new Float(1));
139             asm.add(where, inc ? opc_fadd : opc_fsub);
140             break;
141           case TC_DOUBLE:
142             asm.add(where, opc_ldc2_w, new Double(1));
143             asm.add(where, inc ? opc_dadd : opc_dsub);
144             break;
145           default:
146             throw new CompilerError("invalid type");
147         }
148     }
149 
codeIncDec(Environment env, Context ctx, Assembler asm, boolean inc, boolean prefix, boolean valNeeded)150     void codeIncDec(Environment env, Context ctx, Assembler asm, boolean inc, boolean prefix, boolean valNeeded) {
151 
152         // The 'iinc' instruction cannot be used if an access method call is required.
153         if ((right.op == IDENT) && type.isType(TC_INT) &&
154             (((IdentifierExpression)right).field.isLocal()) && updater == null) {
155             if (valNeeded && !prefix) {
156                 right.codeLoad(env, ctx, asm);
157             }
158             int v = ((LocalMember)((IdentifierExpression)right).field).number;
159             int[] operands = { v, inc ? 1 : -1 };
160             asm.add(where, opc_iinc, operands);
161             if (valNeeded && prefix) {
162                 right.codeLoad(env, ctx, asm);
163             }
164             return;
165 
166         }
167 
168         if (updater == null) {
169             // Field is directly accessible.
170             int depth = right.codeLValue(env, ctx, asm);
171             codeDup(env, ctx, asm, depth, 0);
172             right.codeLoad(env, ctx, asm);
173             if (valNeeded && !prefix) {
174                 codeDup(env, ctx, asm, type.stackSize(), depth);
175             }
176             codeIncDecOp(asm, inc);
177             if (valNeeded && prefix) {
178                 codeDup(env, ctx, asm, type.stackSize(), depth);
179             }
180             right.codeStore(env, ctx, asm);
181         } else {
182             // Must use access methods.
183             updater.startUpdate(env, ctx, asm, (valNeeded && !prefix));
184             codeIncDecOp(asm, inc);
185             updater.finishUpdate(env, ctx, asm, (valNeeded && prefix));
186         }
187     }
188 
189 }
190