Fix coroutine-related VerifyError

The problem was that we spilled the `origin` variable (see test) as Object, because
we determined the type of merge(null, String) incorrectly.

 #KT-15973 Fixed

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

@@ -72,13 +72,9 @@ public class OptimizationBasicInterpreter extends Interpreter<BasicValue> implem
 
     @Override
     public BasicValue newOperation(@NotNull AbstractInsnNode insn) throws AnalyzerException {
-        if (insn.getOpcode() == Opcodes.ACONST_NULL) {
-            return newValue(Type.getObjectType("java/lang/Object"));
-        }
-
         switch (insn.getOpcode()) {
             case ACONST_NULL:
-                return newValue(Type.getObjectType("null"));
+                return NULL_VALUE;
             case ICONST_M1:
             case ICONST_0:
             case ICONST_1:
@@ -362,6 +358,9 @@ public class OptimizationBasicInterpreter extends Interpreter<BasicValue> implem
         // if merge of two references then `lub` is java/lang/Object
         // arrays also are BasicValues with reference type's
         if (isReference(v) && isReference(w)) {
+            if (v == NULL_VALUE) return newValue(w.getType());
+            if (w == NULL_VALUE) return newValue(v.getType());
+
             return StrictBasicValue.REFERENCE_VALUE;
         }
 

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/common/StrictBasicValue.kt

@@ -45,6 +45,9 @@ open class StrictBasicValue(type: Type?) : BasicValue(type) {
         val SHORT_VALUE = StrictBasicValue(Type.SHORT_TYPE)
         @JvmField
         val REFERENCE_VALUE = StrictBasicValue(Type.getObjectType("java/lang/Object"))
+
+        @JvmField
+        val NULL_VALUE = StrictBasicValue(Type.getObjectType("java/lang/Object"))
     }
 
     override fun equals(other: Any?): Boolean {
@@ -60,4 +63,9 @@ open class StrictBasicValue(type: Type?) : BasicValue(type) {
     }
 
     override fun hashCode() = (type?.hashCode() ?: 0)
+
+    override fun toString(): String {
+        if (this === UNINITIALIZED_VALUE) return "."
+        return super.toString()
+    }
 }

compiler/testData/codegen/box/coroutines/mergeNullAndString.kt

@@ -0,0 +1,38 @@
+// WITH_RUNTIME
+// WITH_COROUTINES
+import kotlin.coroutines.experimental.*
+import kotlin.coroutines.experimental.intrinsics.*
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(EmptyContinuation)
+}
+
+var res = ""
+
+suspend fun foo(y: A?): String {
+    val origin: String? = y?.z
+    if (origin != null) {
+        baz(origin)
+        baz(origin)
+    }
+
+    return res
+}
+
+suspend fun baz(y: String): Unit = suspendCoroutineOrReturn { x ->
+    res += y[res.length]
+    x.resume(Unit)
+    COROUTINE_SUSPENDED
+}
+
+class A(val z: String)
+
+fun box(): String {
+    var result = ""
+
+    builder {
+        result = foo(A("OK"))
+    }
+
+    return result
+}

compiler/testData/codegen/light-analysis/coroutines/mergeNullAndString.txt

@@ -0,0 +1,42 @@
+@kotlin.Metadata
+public final class A {
+    private final @org.jetbrains.annotations.NotNull field z: java.lang.String
+    public method <init>(@org.jetbrains.annotations.NotNull p0: java.lang.String): void
+    public final @org.jetbrains.annotations.NotNull method getZ(): java.lang.String
+}
+
+@kotlin.Metadata
+public final class CoroutineUtilKt {
+    public final static @org.jetbrains.annotations.NotNull method handleExceptionContinuation(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): kotlin.coroutines.experimental.Continuation
+    public final static @org.jetbrains.annotations.NotNull method handleResultContinuation(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): kotlin.coroutines.experimental.Continuation
+}
+
+@kotlin.Metadata
+public class EmptyContinuation {
+    public final static field Companion: EmptyContinuation.Companion
+    private final @org.jetbrains.annotations.NotNull field context: kotlin.coroutines.experimental.CoroutineContext
+    inner class EmptyContinuation/Companion
+    public @synthetic.kotlin.jvm.GeneratedByJvmOverloads method <init>(): void
+    public method <init>(@org.jetbrains.annotations.NotNull p0: kotlin.coroutines.experimental.CoroutineContext): void
+    public synthetic method <init>(p0: kotlin.coroutines.experimental.CoroutineContext, p1: int, p2: kotlin.jvm.internal.DefaultConstructorMarker): void
+    public @org.jetbrains.annotations.NotNull method getContext(): kotlin.coroutines.experimental.CoroutineContext
+    public method resume(@org.jetbrains.annotations.Nullable p0: java.lang.Object): void
+    public method resumeWithException(@org.jetbrains.annotations.NotNull p0: java.lang.Throwable): void
+}
+
+@kotlin.Metadata
+public final static class EmptyContinuation/Companion {
+    inner class EmptyContinuation/Companion
+    private method <init>(): void
+}
+
+@kotlin.Metadata
+public final class MergeNullAndStringKt {
+    private static @org.jetbrains.annotations.NotNull field res: java.lang.String
+    public final static @org.jetbrains.annotations.Nullable method baz(@org.jetbrains.annotations.NotNull p0: java.lang.String, @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.experimental.Continuation): java.lang.Object
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+    public final static method builder(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): void
+    public final static @org.jetbrains.annotations.Nullable method foo(@org.jetbrains.annotations.Nullable p0: A, @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.experimental.Continuation): java.lang.Object
+    public final static @org.jetbrains.annotations.NotNull method getRes(): java.lang.String
+    public final static method setRes(@org.jetbrains.annotations.NotNull p0: java.lang.String): void
+}

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -4799,6 +4799,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             doTest(fileName);
         }
 
+        @TestMetadata("mergeNullAndString.kt")
+        public void testMergeNullAndString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/mergeNullAndString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("multipleInvokeCalls.kt")
         public void testMultipleInvokeCalls() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multipleInvokeCalls.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -4799,6 +4799,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("mergeNullAndString.kt")
+        public void testMergeNullAndString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/mergeNullAndString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("multipleInvokeCalls.kt")
         public void testMultipleInvokeCalls() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multipleInvokeCalls.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeCodegenTestGenerated.java

@@ -4799,6 +4799,12 @@ public class LightAnalysisModeCodegenTestGenerated extends AbstractLightAnalysis
             doTest(fileName);
         }
 
+        @TestMetadata("mergeNullAndString.kt")
+        public void testMergeNullAndString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/mergeNullAndString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("multipleInvokeCalls.kt")
         public void testMultipleInvokeCalls() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multipleInvokeCalls.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -5490,6 +5490,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             doTest(fileName);
         }
 
+        @TestMetadata("mergeNullAndString.kt")
+        public void testMergeNullAndString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/mergeNullAndString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("multipleInvokeCalls.kt")
         public void testMultipleInvokeCalls() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multipleInvokeCalls.kt");