KT-14581 Make FixStackAnalyzer tolerant to uninitialized values

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/common/OptimizationBasicInterpreter.java

@@ -31,9 +31,15 @@ import java.util.List;
 import static org.jetbrains.kotlin.codegen.optimization.common.StrictBasicValue.*;
 
 public class OptimizationBasicInterpreter extends Interpreter<BasicValue> implements Opcodes {
+    private final boolean tolerantToUninitializedValues;
+
+    public OptimizationBasicInterpreter(boolean tolerantToUninitializedValues) {
+        super(ASM5);
+        this.tolerantToUninitializedValues = tolerantToUninitializedValues;
+    }
 
     public OptimizationBasicInterpreter() {
-        super(ASM5);
+        this(false);
     }
 
     @Override
@@ -355,7 +361,11 @@ public class OptimizationBasicInterpreter extends Interpreter<BasicValue> implem
     ) {
         if (v.equals(w)) return v;
 
-        if (v == StrictBasicValue.UNINITIALIZED_VALUE || w == StrictBasicValue.UNINITIALIZED_VALUE) {
+        if (tolerantToUninitializedValues) {
+            if (v == StrictBasicValue.UNINITIALIZED_VALUE) return w;
+            if (w == StrictBasicValue.UNINITIALIZED_VALUE) return v;
+        }
+        else if (v == StrictBasicValue.UNINITIALIZED_VALUE || w == StrictBasicValue.UNINITIALIZED_VALUE) {
             return StrictBasicValue.UNINITIALIZED_VALUE;
         }
 

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/fixStack/FixStackAnalyzer.kt

@@ -33,7 +33,7 @@ internal class FixStackAnalyzer(
         owner: String,
         methodNode: MethodNode,
         val context: FixStackContext
-) : MethodAnalyzer<BasicValue>(owner, methodNode, OptimizationBasicInterpreter()) {
+) : MethodAnalyzer<BasicValue>(owner, methodNode, OptimizationBasicInterpreter(/* tolerantToUninitializedValues = */true)) {
     val savedStacks = hashMapOf<AbstractInsnNode, List<BasicValue>>()
     var maxExtraStackSize = 0; private set
 

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/fixStack/LocalVariablesManager.kt

@@ -44,6 +44,10 @@ internal class LocalVariablesManager(val context: FixStackContext, val methodNod
     }
 
     private fun allocateNewHandle(numRestoreStackMarkers: Int, saveStackMarker: AbstractInsnNode, savedStackValues: List<BasicValue>): SavedStackDescriptor {
+        if (savedStackValues.any { it.type == null }) {
+            throw AssertionError("Uninitialized value on stack at ${methodNode.instructions.indexOf(saveStackMarker)}")
+        }
+
         val firstUnusedLocalVarIndex = getFirstUnusedLocalVariableIndex()
         val savedStackDescriptor = SavedStackDescriptor(savedStackValues, firstUnusedLocalVarIndex)
         updateMaxLocals(savedStackDescriptor.firstUnusedLocalVarIndex)