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Make CHECKCAST Object not break tail-call optimization

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Since CHECKCAST Object does nothing for return value of suspend
function - the function returns references only, this is safe.
 #KT-49157 Fixed
This commit is contained in:
Ilmir Usmanov
2021-10-08 17:20:27 +02:00
committed by Space
parent 4a99f04b41
commit f760cd6736
6 changed files with 65 additions and 5 deletions
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compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/TailCallOptimization.kt
+10 -5
View File
@@ -17,10 +17,7 @@ import org.jetbrains.kotlin.utils.sure
import org.jetbrains.org.objectweb.asm.Label
import org.jetbrains.org.objectweb.asm.Opcodes
import org.jetbrains.org.objectweb.asm.Type
import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
import org.jetbrains.org.objectweb.asm.tree.LineNumberNode
import org.jetbrains.org.objectweb.asm.tree.MethodNode
import org.jetbrains.org.objectweb.asm.tree.VarInsnNode
import org.jetbrains.org.objectweb.asm.tree.*
import org.jetbrains.org.objectweb.asm.tree.analysis.BasicInterpreter
import org.jetbrains.org.objectweb.asm.tree.analysis.BasicValue
import org.jetbrains.org.objectweb.asm.tree.analysis.Frame
@@ -155,7 +152,7 @@ internal class MethodNodeExaminer(
}
if (!insn.isMeaningful || insn.opcode in SAFE_OPCODES || insn.isInvisibleInDebugVarInsn(methodNode) || isInlineMarker(insn)
|| insn.isSafeUnitInstance() || insn.isAreturnAfterSafeUnitInstance()
|| insn.isSafeUnitInstance() || insn.isAreturnAfterSafeUnitInstance() || insn.isCheckcastObject()
) {
setOf()
} else null
@@ -187,6 +184,9 @@ internal class MethodNodeExaminer(
}
}
private fun AbstractInsnNode.isCheckcastObject(): Boolean =
opcode == Opcodes.CHECKCAST && (this as TypeInsnNode).desc == AsmTypes.OBJECT_TYPE.internalName
private fun AbstractInsnNode?.isInvisibleInDebugVarInsn(methodNode: MethodNode): Boolean {
val insns = methodNode.instructions
val index = insns.indexOf(this)
@@ -225,6 +225,11 @@ private class TcoInterpreter(private val suspensionPoints: List<SuspensionPoint>
}
override fun unaryOperation(insn: AbstractInsnNode, value: BasicValue?): BasicValue? {
// Assume, that CHECKCAST Object does not break tail-call optimization
// TODO: Investigate, whether any CHECKCAST is safe in terms of tail-call optimization
if (value is FromSuspensionPointValue && insn.isCheckcastObject()) {
return value
}
return super.unaryOperation(insn, value).convert(insn)
}