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Fix start of local var visibility in classfiles #8754

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merged 1 commit into from
Apr 21, 2020
Merged

Fix start of local var visibility in classfiles #8754

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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/backend/jvm/BCodeBodyBuilder.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -271,8 +271,8 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
val Local(tk, _, idx, isSynth) = loc
if (rhs == EmptyTree) { emitZeroOf(tk) }
else { genLoad(rhs, tk) }
val localVarStart = currProgramPoint()
bc.store(idx, tk)
val localVarStart = currProgramPoint()
if (!isSynth) { // there are case <synthetic> ValDef's emitted by patmat
varsInScope ::= (sym -> localVarStart)
}
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38 changes: 37 additions & 1 deletion compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala
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Expand Up @@ -9,7 +9,7 @@ import asm.tree._

import scala.tools.asm.Opcodes
import scala.jdk.CollectionConverters._

import Opcodes._

class TestBCode extends DottyBytecodeTest {
import ASMConverters._
Expand Down Expand Up @@ -786,6 +786,42 @@ class TestBCode extends DottyBytecodeTest {
}
}


@Test // wrong local variable table for methods containing while loops
def t9179(): Unit = {
val code =
"""class C {
| def t(): Unit = {
| var x = ""
| while (x != null) {
| foo()
| x = null
| }
| bar()
| }
| def foo(): Unit = ()
| def bar(): Unit = ()
|}
""".stripMargin
checkBCode(code) { dir =>
val c = loadClassNode(dir.lookupName("C.class", directory = false).input, skipDebugInfo = false)
val t = getMethod(c, "t")
val instructions = instructionsFromMethod(t)
val isFrameLine = (x: Instruction) => x.isInstanceOf[FrameEntry] || x.isInstanceOf[LineNumber]
// TODO: The same test in scalac uses different labels because their LineNumberTable isn't the same as ours,
// this should be investigated.
assertSameCode(instructions.filterNot(isFrameLine), List(
Label(0), Ldc(LDC, ""), VarOp(ASTORE, 1),
Label(5), VarOp(ALOAD, 1), Jump(IFNULL, Label(19)),
Label(10), VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "C", "foo", "()V", false), Label(14), Op(ACONST_NULL), VarOp(ASTORE, 1), Jump(GOTO, Label(5)),
Label(19), VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "C", "bar", "()V", false), Label(24), Op(RETURN), Label(26)))
val labels = instructions collect { case l: Label => l }
val x = convertMethod(t).localVars.find(_.name == "x").get
assertEquals(x.start, labels(1))
assertEquals(x.end, labels(5))
}
}

@Test
def invocationReceivers(): Unit = {
import Opcodes._
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