1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* NSC -- new Scala compiler
* Copyright 2005-2011 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import java.lang.ArithmeticException
/** This class ...
*
* @author Martin Odersky
* @version 1.0
*/
abstract class ConstantFolder {
val global: Global
import global._
import definitions._
/** If tree is a constant operation, replace with result. */
def apply(tree: Tree): Tree = fold(tree, tree match {
case Apply(Select(Literal(x), op), List(Literal(y))) => foldBinop(op, x, y)
case Select(Literal(x), op) => foldUnop(op, x)
case _ => null
})
/** If tree is a constant value that can be converted to type `pt', perform
* the conversion.
*
* @param tree ...
* @param pt ...
*/
def apply(tree: Tree, pt: Type): Tree = fold(apply(tree), tree.tpe match {
case ConstantType(x) => x convertTo pt
case _ => null
})
private def fold(tree: Tree, compX: => Constant): Tree =
try {
val x = compX
if ((x ne null) && x.tag != UnitTag) tree setType ConstantType(x)
else tree
} catch {
case _: ArithmeticException => tree // the code will crash at runtime,
// but that is better than the
// compiler itself crashing
}
private def foldUnop(op: Name, x: Constant): Constant = (op, x.tag) match {
case (nme.UNARY_!, BooleanTag) => Constant(!x.booleanValue)
case (nme.UNARY_~ , IntTag ) => Constant(~x.intValue)
case (nme.UNARY_~ , LongTag ) => Constant(~x.longValue)
case (nme.UNARY_+ , IntTag ) => Constant(+x.intValue)
case (nme.UNARY_+ , LongTag ) => Constant(+x.longValue)
case (nme.UNARY_+ , FloatTag ) => Constant(+x.floatValue)
case (nme.UNARY_+ , DoubleTag ) => Constant(+x.doubleValue)
case (nme.UNARY_- , IntTag ) => Constant(-x.intValue)
case (nme.UNARY_- , LongTag ) => Constant(-x.longValue)
case (nme.UNARY_- , FloatTag ) => Constant(-x.floatValue)
case (nme.UNARY_- , DoubleTag ) => Constant(-x.doubleValue)
case _ => null
}
/** These are local helpers to keep foldBinop from overly taxing the
* optimizer.
*/
private def foldBooleanOp(op: Name, x: Constant, y: Constant): Constant = op match {
case nme.ZOR => Constant(x.booleanValue | y.booleanValue)
case nme.OR => Constant(x.booleanValue | y.booleanValue)
case nme.XOR => Constant(x.booleanValue ^ y.booleanValue)
case nme.ZAND => Constant(x.booleanValue & y.booleanValue)
case nme.AND => Constant(x.booleanValue & y.booleanValue)
case nme.EQ => Constant(x.booleanValue == y.booleanValue)
case nme.NE => Constant(x.booleanValue != y.booleanValue)
case _ => null
}
private def foldSubrangeOp(op: Name, x: Constant, y: Constant): Constant = op match {
case nme.OR => Constant(x.intValue | y.intValue)
case nme.XOR => Constant(x.intValue ^ y.intValue)
case nme.AND => Constant(x.intValue & y.intValue)
case nme.LSL => Constant(x.intValue << y.intValue)
case nme.LSR => Constant(x.intValue >>> y.intValue)
case nme.ASR => Constant(x.intValue >> y.intValue)
case nme.EQ => Constant(x.intValue == y.intValue)
case nme.NE => Constant(x.intValue != y.intValue)
case nme.LT => Constant(x.intValue < y.intValue)
case nme.GT => Constant(x.intValue > y.intValue)
case nme.LE => Constant(x.intValue <= y.intValue)
case nme.GE => Constant(x.intValue >= y.intValue)
case nme.ADD => Constant(x.intValue + y.intValue)
case nme.SUB => Constant(x.intValue - y.intValue)
case nme.MUL => Constant(x.intValue * y.intValue)
case nme.DIV => Constant(x.intValue / y.intValue)
case nme.MOD => Constant(x.intValue % y.intValue)
case _ => null
}
private def foldLongOp(op: Name, x: Constant, y: Constant): Constant = op match {
case nme.OR => Constant(x.longValue | y.longValue)
case nme.XOR => Constant(x.longValue ^ y.longValue)
case nme.AND => Constant(x.longValue & y.longValue)
case nme.LSL => Constant(x.longValue << y.longValue)
case nme.LSR => Constant(x.longValue >>> y.longValue)
case nme.ASR => Constant(x.longValue >> y.longValue)
case nme.EQ => Constant(x.longValue == y.longValue)
case nme.NE => Constant(x.longValue != y.longValue)
case nme.LT => Constant(x.longValue < y.longValue)
case nme.GT => Constant(x.longValue > y.longValue)
case nme.LE => Constant(x.longValue <= y.longValue)
case nme.GE => Constant(x.longValue >= y.longValue)
case nme.ADD => Constant(x.longValue + y.longValue)
case nme.SUB => Constant(x.longValue - y.longValue)
case nme.MUL => Constant(x.longValue * y.longValue)
case nme.DIV => Constant(x.longValue / y.longValue)
case nme.MOD => Constant(x.longValue % y.longValue)
case _ => null
}
private def foldFloatOp(op: Name, x: Constant, y: Constant): Constant = op match {
case nme.EQ => Constant(x.floatValue == y.floatValue)
case nme.NE => Constant(x.floatValue != y.floatValue)
case nme.LT => Constant(x.floatValue < y.floatValue)
case nme.GT => Constant(x.floatValue > y.floatValue)
case nme.LE => Constant(x.floatValue <= y.floatValue)
case nme.GE => Constant(x.floatValue >= y.floatValue)
case nme.ADD => Constant(x.floatValue + y.floatValue)
case nme.SUB => Constant(x.floatValue - y.floatValue)
case nme.MUL => Constant(x.floatValue * y.floatValue)
case nme.DIV => Constant(x.floatValue / y.floatValue)
case nme.MOD => Constant(x.floatValue % y.floatValue)
case _ => null
}
private def foldDoubleOp(op: Name, x: Constant, y: Constant): Constant = op match {
case nme.EQ => Constant(x.doubleValue == y.doubleValue)
case nme.NE => Constant(x.doubleValue != y.doubleValue)
case nme.LT => Constant(x.doubleValue < y.doubleValue)
case nme.GT => Constant(x.doubleValue > y.doubleValue)
case nme.LE => Constant(x.doubleValue <= y.doubleValue)
case nme.GE => Constant(x.doubleValue >= y.doubleValue)
case nme.ADD => Constant(x.doubleValue + y.doubleValue)
case nme.SUB => Constant(x.doubleValue - y.doubleValue)
case nme.MUL => Constant(x.doubleValue * y.doubleValue)
case nme.DIV => Constant(x.doubleValue / y.doubleValue)
case nme.MOD => Constant(x.doubleValue % y.doubleValue)
case _ => null
}
private def foldBinop(op: Name, x: Constant, y: Constant): Constant = {
val optag =
if (x.tag == y.tag) x.tag
else if (x.isNumeric && y.isNumeric) math.max(x.tag, y.tag)
else NoTag
try optag match {
case BooleanTag => foldBooleanOp(op, x, y)
case ByteTag | ShortTag | CharTag | IntTag => foldSubrangeOp(op, x, y)
case LongTag => foldLongOp(op, x, y)
case FloatTag => foldFloatOp(op, x, y)
case DoubleTag => foldDoubleOp(op, x, y)
case StringTag if op == nme.ADD => Constant(x.stringValue + y.stringValue)
case _ => null
}
catch {
case ex: ArithmeticException => null
}
}
}
|