PSI2IR: KT-49485 chunk ktConditions to avoid stackoverflow

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/BranchingExpressionGenerator.kt

@@ -112,18 +112,21 @@ class BranchingExpressionGenerator(statementGenerator: StatementGenerator) : Sta
                 break
             }
 
-            var irBranchCondition: IrExpression? = null
-            for (ktCondition in ktEntry.conditions) {
-                val irCondition =
-                    if (irSubject != null)
-                        generateWhenConditionWithSubject(ktCondition, irSubject, expression.subjectExpression)
-                    else
-                        generateWhenConditionNoSubject(ktCondition)
-                irBranchCondition = irBranchCondition?.let { context.whenComma(it, irCondition) } ?: irCondition
-            }
+            // chunk conditions to avoid stackoverflow later when IrWhen is visited
+            for (ktConditions in ktEntry.conditions.toList().chunked(64)) {
+                var irBranchCondition: IrExpression? = null
+                for (ktCondition in ktConditions) {
+                    val irCondition =
+                        if (irSubject != null)
+                            generateWhenConditionWithSubject(ktCondition, irSubject, expression.subjectExpression)
+                        else
+                            generateWhenConditionNoSubject(ktCondition)
+                    irBranchCondition = irBranchCondition?.let { context.whenComma(it, irCondition) } ?: irCondition
+                }
 
-            val irBranchResult = ktEntry.expression!!.genExpr()
-            irWhen.branches.add(IrBranchImpl(irBranchCondition!!, irBranchResult))
+                val irBranchResult = ktEntry.expression!!.genExpr()
+                irWhen.branches.add(IrBranchImpl(irBranchCondition!!, irBranchResult))
+            }
         }
         if (!hasExplicitElseBranch) {
             addElseBranchForExhaustiveWhenIfNeeded(irWhen, expression)