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Fix #746: Generate efficient try cases for parameterized exceptions #3929

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Merged
merged 2 commits into from
Jan 28, 2018
Merged

Fix #746: Generate efficient try cases for parameterized exceptions #3929

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904fed2
Fix #746: Generate efficient try cases for parameterized exceptions
odersky Jan 26, 2018
578b334
Add bytecode test
allanrenucci Jan 26, 2018
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2 changes: 2 additions & 0 deletions compiler/src/dotty/tools/dotc/transform/TryCatchPatterns.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,8 @@ class TryCatchPatterns extends MiniPhase {
(pre == NoPrefix || pre.widen.typeSymbol.isStatic) && // Does not require outer class check
!tp.symbol.is(Flags.Trait) && // Traits not supported by JVM
tp.derivesFrom(defn.ThrowableClass)
case tp: AppliedType =>
isSimpleThrowable(tp.tycon)
case _ =>
false
}
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28 changes: 28 additions & 0 deletions compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala
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Expand Up @@ -3,6 +3,8 @@ package dotty.tools.backend.jvm
import org.junit.Assert._
import org.junit.Test

import scala.tools.asm.Opcodes

class TestBCode extends DottyBytecodeTest {
import ASMConverters._
@Test def nullChecks = {
Expand Down Expand Up @@ -213,4 +215,30 @@ class TestBCode extends DottyBytecodeTest {
assert(!arrayWrapped, "Arrays should not be wrapped when passed to a Java varargs method\n")
}
}

@Test def efficientTryCases = {
val source =
"""
|class Test {
| def test =
| try print("foo")
| catch {
| case _: scala.runtime.NonLocalReturnControl[_] => ()
| }
|}
""".stripMargin

checkBCode(source) { dir =>
val moduleIn = dir.lookupName("Test.class", directory = false)
val moduleNode = loadClassNode(moduleIn.input)
val method = getMethod(moduleNode, "test")

val hasInstanceof = instructionsFromMethod(method).exists {
case TypeOp(Opcodes.INSTANCEOF, _) => true
case _ => false
}

assert(!hasInstanceof, "Try case should not issue INSTANCEOF opcode\n")
}
}
}