[FIR] Add cfg nodes for classes

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/ControlFlowGraph.kt

@@ -133,7 +133,25 @@ class UnionFunctionCallArgumentsNode(owner: ControlFlowGraph, override val fir:
     }
 }
 
-// ----------------------------------- Anonymous object -----------------------------------
+// ----------------------------------- Classes -----------------------------------
+
+class ClassEnterNode(owner: ControlFlowGraph, override val fir: FirClass<*>, level: Int, id: Int) : CFGNode<FirClass<*>>(owner, level, id) {
+    override fun <R, D> accept(visitor: ControlFlowGraphVisitor<R, D>, data: D): R {
+        return visitor.visitClassEnterNode(this, data)
+    }
+}
+
+class ClassExitNode(owner: ControlFlowGraph, override val fir: FirClass<*>, level: Int, id: Int) : CFGNode<FirClass<*>>(owner, level, id) {
+    override fun <R, D> accept(visitor: ControlFlowGraphVisitor<R, D>, data: D): R {
+        return visitor.visitClassExitNode(this, data)
+    }
+}
+
+class LocalClassExitNode(owner: ControlFlowGraph, override val fir: FirRegularClass, level: Int, id: Int) : CFGNode<FirRegularClass>(owner, level, id) {
+    override fun <R, D> accept(visitor: ControlFlowGraphVisitor<R, D>, data: D): R {
+        return visitor.visitLocalClassExitNode(this, data)
+    }
+}
 
 class AnonymousObjectExitNode(owner: ControlFlowGraph, override val fir: FirAnonymousObject, level: Int, id: Int) : CFGNode<FirAnonymousObject>(owner, level, id) {
     override fun <R, D> accept(visitor: ControlFlowGraphVisitor<R, D>, data: D): R {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/ControlFlowGraphNodeBuilder.kt

@@ -201,3 +201,16 @@ fun ControlFlowGraphBuilder.createAnonymousObjectExitNode(fir: FirAnonymousObjec
 
 fun ControlFlowGraphBuilder.createUnionFunctionCallArgumentsNode(fir: FirElement): UnionFunctionCallArgumentsNode =
     UnionFunctionCallArgumentsNode(graph, fir, levelCounter, createId())
+
+fun ControlFlowGraphBuilder.createClassEnterNode(fir: FirClass<*>): ClassEnterNode =
+    ClassEnterNode(graph, fir, levelCounter, createId()).also {
+        graph.enterNode = it
+    }
+
+fun ControlFlowGraphBuilder.createClassExitNode(fir: FirClass<*>): ClassExitNode =
+    ClassExitNode(graph, fir, levelCounter, createId()).also {
+        graph.exitNode = it
+    }
+
+fun ControlFlowGraphBuilder.createLocalClassExitNode(fir: FirRegularClass): LocalClassExitNode =
+    LocalClassExitNode(graph, fir, levelCounter, createId())

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/ControlFlowGraphVisitor.kt

@@ -32,12 +32,24 @@ abstract class ControlFlowGraphVisitor<out R, in D> {
         return visitNode(node, data)
     }
 
-    // ----------------------------------- Anonymous object -----------------------------------
+    // ----------------------------------- Classes -----------------------------------
 
     open fun visitAnonymousObjectExitNode(node: AnonymousObjectExitNode, data: D): R {
         return visitNode(node, data)
     }
 
+    open fun visitClassEnterNode(node: ClassEnterNode, data: D): R {
+        return visitNode(node, data)
+    }
+
+    open fun visitClassExitNode(node: ClassExitNode, data: D): R {
+        return visitNode(node, data)
+    }
+
+    open fun visitLocalClassExitNode(node: LocalClassExitNode, data: D): R {
+        return visitNode(node, data)
+    }
+
     // ----------------------------------- Property -----------------------------------
 
     open fun visitPropertyInitializerEnterNode(node: PropertyInitializerEnterNode, data: D): R {