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
|
package scala.tools.nsc
package backend.jvm
package opt
import org.junit.runner.RunWith
import org.junit.runners.JUnit4
import org.junit.Test
import scala.tools.asm.Opcodes._
import org.junit.Assert._
import CodeGenTools._
import scala.tools.partest.ASMConverters
import ASMConverters._
import scala.tools.testing.ClearAfterClass
object EmptyExceptionHandlersTest extends ClearAfterClass.Clearable {
var noOptCompiler = newCompiler(extraArgs = "-Ybackend:GenBCode -Yopt:l:none")
var dceCompiler = newCompiler(extraArgs = "-Ybackend:GenBCode -Yopt:unreachable-code")
def clear(): Unit = {
noOptCompiler = null
dceCompiler = null
}
}
@RunWith(classOf[JUnit4])
class EmptyExceptionHandlersTest extends ClearAfterClass {
ClearAfterClass.stateToClear = EmptyExceptionHandlersTest
val noOptCompiler = EmptyExceptionHandlersTest.noOptCompiler
val dceCompiler = EmptyExceptionHandlersTest.dceCompiler
val exceptionDescriptor = "java/lang/Exception"
@Test
def eliminateEmpty(): Unit = {
val handlers = List(ExceptionHandler(Label(1), Label(2), Label(2), Some(exceptionDescriptor)))
val asmMethod = genMethod(handlers = handlers)(
Label(1),
Label(2),
Op(RETURN)
)
assertTrue(convertMethod(asmMethod).handlers.length == 1)
LocalOptImpls.removeEmptyExceptionHandlers(asmMethod)
assertTrue(convertMethod(asmMethod).handlers.isEmpty)
}
@Test
def eliminateHandlersGuardingNops(): Unit = {
val handlers = List(ExceptionHandler(Label(1), Label(2), Label(2), Some(exceptionDescriptor)))
val asmMethod = genMethod(handlers = handlers)(
Label(1), // nops only
Jump(GOTO, Label(3)),
Label(3),
Jump(GOTO, Label(4)),
Label(2), // handler
Op(ACONST_NULL),
Op(ATHROW),
Label(4), // return
Op(RETURN)
)
assertTrue(convertMethod(asmMethod).handlers.length == 1)
LocalOptImpls.removeEmptyExceptionHandlers(asmMethod)
assertTrue(convertMethod(asmMethod).handlers.isEmpty)
}
@Test
def eliminateUnreachableHandler(): Unit = {
val code = "def f: Unit = try { } catch { case _: Exception => println(0) }; println(1)"
assertTrue(singleMethod(noOptCompiler)(code).handlers.length == 1)
val optMethod = singleMethod(dceCompiler)(code)
assertTrue(optMethod.handlers.isEmpty)
val code2 =
"""def f: Unit = {
| println(0)
| return
| try { throw new Exception("") } // removed by dce, so handler will be removed as well
| catch { case _: Exception => println(1) }
| println(2)
|}""".stripMargin
assertTrue(singleMethod(dceCompiler)(code2).handlers.isEmpty)
}
@Test
def keepAliveHandlers(): Unit = {
val code =
"""def f: Int = {
| println(0)
| try { 1 }
| catch { case _: Exception => 2 }
|}""".stripMargin
assertTrue(singleMethod(dceCompiler)(code).handlers.length == 1)
}
}
|
