[FIR] Fix collectDataForNode backward traverse

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/cfa/CfgTraverser.kt

@@ -55,6 +55,9 @@ private fun <I : ControlFlowInfo<I, K, V>, K : Any, V : Any> ControlFlowGraph.co
 ) {
     val nodes = getNodesInOrder(direction)
     for (node in nodes) {
+        if (direction == TraverseDirection.Backward && node is CFGNodeWithCfgOwner<*>) {
+            node.subGraphs.forEach { it.collectDataForNodeInternal(direction, initialInfo, visitor, nodeMap, changed) }
+        }
         if (!(node.isEnterNode(direction) && node.owner.owner == null)) {
             val previousNodes = when (direction) {
                 TraverseDirection.Forward -> node.previousCfgNodes
@@ -69,7 +72,7 @@ private fun <I : ControlFlowInfo<I, K, V>, K : Any, V : Any> ControlFlowGraph.co
                 nodeMap[node] = newData
             }
         }
-        if (node is CFGNodeWithCfgOwner<*>) {
+        if (direction == TraverseDirection.Forward && node is CFGNodeWithCfgOwner<*>) {
             node.subGraphs.forEach { it.collectDataForNodeInternal(direction, initialInfo, visitor, nodeMap, changed) }
         }
     }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/cfa/CfgUtils.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.analysis.cfa
 
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.CFGNode
+import org.jetbrains.kotlin.fir.resolve.dfa.cfg.CFGNodeWithCfgOwner
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.ControlFlowGraph
 
 fun ControlFlowGraph.getEnterNode(direction: TraverseDirection): CFGNode<*> = when (direction) {
@@ -34,7 +35,14 @@ val CFGNode<*>.previousCfgNodes: List<CFGNode<*>>
     }
 
 val CFGNode<*>.followingCfgNodes: List<CFGNode<*>>
-    get() = followingNodes.filter {
+    get() {
-        val kind = outgoingEdges.getValue(it)
+        val nodes = mutableListOf<CFGNode<*>>()
-        kind.usedInCfa && !kind.isDead
+
+        followingNodes.filterTo(nodes) {
+            val kind = outgoingEdges.getValue(it)
+            kind.usedInCfa && !kind.isDead
+        }
+        (this as? CFGNodeWithCfgOwner<*>)?.subGraphs?.mapTo(nodes) { it.enterNode }
+
+        return nodes
     }