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FIR checker: make unused checker path-sensitive

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This commit is contained in:
Jinseong Jeon
2020-11-24 14:42:51 -08:00
committed by Mikhail Glukhikh
parent 3d7d87ace5
commit 168503573a
1 changed files with 128 additions and 67 deletions
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compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/UnusedChecker.kt
+128 -67
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@@ -36,41 +36,52 @@ object UnusedChecker : FirControlFlowChecker() {
}
class CfaVisitor(
val data: Map<CFGNode<*>, VariableStatusInfo>,
val data: Map<CFGNode<*>, PathAwareVariableStatusInfo>,
val reporter: DiagnosticReporter
) : ControlFlowGraphVisitorVoid() {
override fun visitNode(node: CFGNode<*>) {}
override fun visitVariableAssignmentNode(node: VariableAssignmentNode) {
val variableSymbol = (node.fir.calleeReference as? FirResolvedNamedReference)?.resolvedSymbol ?: return
val data = data[node]?.get(variableSymbol) ?: return
if (data == VariableStatus.ONLY_WRITTEN_NEVER_READ) {
// todo: report case like "a += 1" where `a` `doesn't writes` different way (special for Idea)
val source = node.fir.lValue.source
reporter.report(source, FirErrors.ASSIGNED_VALUE_IS_NEVER_READ)
val dataPerNode = data[node] ?: return
for (label in dataPerNode.keys) {
val data = dataPerNode[label]!![variableSymbol] ?: continue
if (data == VariableStatus.ONLY_WRITTEN_NEVER_READ) {
// todo: report case like "a += 1" where `a` `doesn't writes` different way (special for Idea)
val source = node.fir.lValue.source
reporter.report(source, FirErrors.ASSIGNED_VALUE_IS_NEVER_READ)
// To avoid duplicate reports, stop investigating remaining paths once reported.
break
}
}
}
override fun visitVariableDeclarationNode(node: VariableDeclarationNode) {
val variableSymbol = node.fir.symbol
if (variableSymbol.isLoopIterator) return
val data = data[node]?.get(variableSymbol) ?: return
val dataPerNode = data[node] ?: return
for (label in dataPerNode.keys) {
val data = dataPerNode[label]!![variableSymbol] ?: continue
val variableSource = variableSymbol.fir.source.takeIf { it?.elementType != KtNodeTypes.DESTRUCTURING_DECLARATION }
when {
data == VariableStatus.UNUSED -> {
if ((node.fir.initializer as? FirFunctionCall)?.isIterator != true) {
reporter.report(variableSource, FirErrors.UNUSED_VARIABLE)
val variableSource = variableSymbol.fir.source.takeIf { it?.elementType != KtNodeTypes.DESTRUCTURING_DECLARATION }
when {
data == VariableStatus.UNUSED -> {
if ((node.fir.initializer as? FirFunctionCall)?.isIterator != true) {
reporter.report(variableSource, FirErrors.UNUSED_VARIABLE)
break
}
}
data.isRedundantInit -> {
val source = variableSymbol.fir.initializer?.source
reporter.report(source, FirErrors.VARIABLE_INITIALIZER_IS_REDUNDANT)
break
}
data == VariableStatus.ONLY_WRITTEN_NEVER_READ -> {
reporter.report(variableSource, FirErrors.VARIABLE_NEVER_READ)
break
}
else -> {
}
}
data.isRedundantInit -> {
val source = variableSymbol.fir.initializer?.source
reporter.report(source, FirErrors.VARIABLE_INITIALIZER_IS_REDUNDANT)
}
data == VariableStatus.ONLY_WRITTEN_NEVER_READ -> {
reporter.report(variableSource, FirErrors.VARIABLE_NEVER_READ)
}
else -> {
}
}
}
@@ -122,72 +133,102 @@ object UnusedChecker : FirControlFlowChecker() {
}
class PathAwareVariableStatusInfo(
map: PersistentMap<EdgeLabel, VariableStatusInfo> = persistentMapOf()
) : PathAwareControlFlowInfo<PathAwareVariableStatusInfo, VariableStatusInfo>(map) {
companion object {
val EMPTY = PathAwareVariableStatusInfo(persistentMapOf(NormalPath to VariableStatusInfo.EMPTY))
}
override val constructor: (PersistentMap<EdgeLabel, VariableStatusInfo>) -> PathAwareVariableStatusInfo =
::PathAwareVariableStatusInfo
override val empty: () -> PathAwareVariableStatusInfo =
::EMPTY
}
private class ValueWritesWithoutReading(
private val localProperties: Set<FirPropertySymbol>
) : ControlFlowGraphVisitor<VariableStatusInfo, Collection<VariableStatusInfo>>() {
fun getData(graph: ControlFlowGraph): Map<CFGNode<*>, VariableStatusInfo> {
return graph.collectDataForNode(TraverseDirection.Backward, VariableStatusInfo.EMPTY, this)
) : ControlFlowGraphVisitor<PathAwareVariableStatusInfo, Collection<Pair<EdgeLabel, PathAwareVariableStatusInfo>>>() {
fun getData(graph: ControlFlowGraph): Map<CFGNode<*>, PathAwareVariableStatusInfo> {
return graph.collectPathAwareDataForNode(TraverseDirection.Backward, PathAwareVariableStatusInfo.EMPTY, this)
}
override fun visitNode(node: CFGNode<*>, data: Collection<VariableStatusInfo>): VariableStatusInfo {
if (data.isEmpty()) return VariableStatusInfo.EMPTY
return data.reduce(VariableStatusInfo::merge)
override fun visitNode(
node: CFGNode<*>,
data: Collection<Pair<EdgeLabel, PathAwareVariableStatusInfo>>
): PathAwareVariableStatusInfo {
if (data.isEmpty()) return PathAwareVariableStatusInfo.EMPTY
return data.map { (label, info) -> info.applyLabel(node, label) }
.reduce(PathAwareVariableStatusInfo::merge)
}
override fun visitVariableDeclarationNode(node: VariableDeclarationNode, data: Collection<VariableStatusInfo>): VariableStatusInfo {
override fun visitVariableDeclarationNode(
node: VariableDeclarationNode,
data: Collection<Pair<EdgeLabel, PathAwareVariableStatusInfo>>
): PathAwareVariableStatusInfo {
val dataForNode = visitNode(node, data)
if (node.fir.source?.kind is FirFakeSourceElementKind) return dataForNode
val symbol = node.fir.symbol
return when (dataForNode[symbol]) {
null -> {
dataForNode.put(symbol, VariableStatus.UNUSED)
}
VariableStatus.ONLY_WRITTEN_NEVER_READ, VariableStatus.WRITTEN_AFTER_READ -> {
if (node.fir.initializer != null && dataForNode[symbol]?.isRead == true) {
val newData = dataForNode[symbol] ?: VariableStatus.UNUSED
newData.isRedundantInit = true
dataForNode.put(symbol, newData)
} else if (node.fir.initializer != null) {
dataForNode.put(symbol, VariableStatus.ONLY_WRITTEN_NEVER_READ)
} else {
dataForNode
return update(dataForNode, symbol) { prev ->
when (prev) {
null -> {
VariableStatus.UNUSED
}
VariableStatus.ONLY_WRITTEN_NEVER_READ, VariableStatus.WRITTEN_AFTER_READ -> {
if (node.fir.initializer != null && prev.isRead) {
prev.isRedundantInit = true
prev
} else if (node.fir.initializer != null) {
VariableStatus.ONLY_WRITTEN_NEVER_READ
} else {
null
}
}
VariableStatus.READ -> {
VariableStatus.READ
}
else -> {
null
}
}
VariableStatus.READ -> {
dataForNode.put(symbol, VariableStatus.READ)
}
else -> {
dataForNode
}
}
}
override fun visitVariableAssignmentNode(node: VariableAssignmentNode, data: Collection<VariableStatusInfo>): VariableStatusInfo {
override fun visitVariableAssignmentNode(
node: VariableAssignmentNode,
data: Collection<Pair<EdgeLabel, PathAwareVariableStatusInfo>>
): PathAwareVariableStatusInfo {
val dataForNode = visitNode(node, data)
val reference = node.fir.lValue as? FirResolvedNamedReference ?: return dataForNode
val symbol = reference.resolvedSymbol as? FirPropertySymbol ?: return dataForNode
val toPut = when {
symbol !in localProperties -> {
null
}
dataForNode[symbol] == VariableStatus.READ -> {
VariableStatus.WRITTEN_AFTER_READ
}
dataForNode[symbol] == VariableStatus.WRITTEN_AFTER_READ -> {
VariableStatus.ONLY_WRITTEN_NEVER_READ
}
else -> {
VariableStatus.ONLY_WRITTEN_NEVER_READ.merge(dataForNode[symbol] ?: VariableStatus.UNUSED)
return update(dataForNode, symbol) update@{ prev ->
val toPut = when {
symbol !in localProperties -> {
null
}
prev == VariableStatus.READ -> {
VariableStatus.WRITTEN_AFTER_READ
}
prev == VariableStatus.WRITTEN_AFTER_READ -> {
VariableStatus.ONLY_WRITTEN_NEVER_READ
}
else -> {
VariableStatus.ONLY_WRITTEN_NEVER_READ.merge(prev ?: VariableStatus.UNUSED)
}
}
toPut ?: return@update null
toPut.isRead = prev?.isRead ?: false
toPut
}
toPut ?: return dataForNode
toPut.isRead = dataForNode[symbol]?.isRead ?: false
return dataForNode.put(symbol, toPut)
}
override fun visitQualifiedAccessNode(node: QualifiedAccessNode, data: Collection<VariableStatusInfo>): VariableStatusInfo {
override fun visitQualifiedAccessNode(
node: QualifiedAccessNode,
data: Collection<Pair<EdgeLabel, PathAwareVariableStatusInfo>>
): PathAwareVariableStatusInfo {
val dataForNode = visitNode(node, data)
if (node.fir.source?.kind is FirFakeSourceElementKind) return dataForNode
val reference = node.fir.calleeReference as? FirResolvedNamedReference ?: return dataForNode
@@ -197,7 +238,27 @@ object UnusedChecker : FirControlFlowChecker() {
val status = VariableStatus.READ
status.isRead = true
return dataForNode.put(symbol, status)
return update(dataForNode, symbol) { status }
}
private fun update(
info: PathAwareVariableStatusInfo,
symbol: FirPropertySymbol,
updater: (VariableStatus?) -> VariableStatus?,
): PathAwareVariableStatusInfo {
var resultMap = persistentMapOf<EdgeLabel, VariableStatusInfo>()
var changed = false
for (label in info.keys) {
val dataPerLabel = info[label]!!
val v = updater.invoke(dataPerLabel[symbol])
if (v != null) {
resultMap = resultMap.put(label, dataPerLabel.put(symbol, v))
changed = true
} else {
resultMap = resultMap.put(label, dataPerLabel)
}
}
return if (changed) PathAwareVariableStatusInfo(resultMap) else info
}
}