diff --git a/idea/idea-completion/testData/basic/common/ClassRedeclaration1.kt b/idea/idea-completion/testData/basic/common/ClassRedeclaration1.kt
index 7c203a21ca9..73c731dfb1c 100644
--- a/idea/idea-completion/testData/basic/common/ClassRedeclaration1.kt
+++ b/idea/idea-completion/testData/basic/common/ClassRedeclaration1.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class A {
   fun f() : A<caret>
 }
diff --git a/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt b/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt
index 3432ee1fa20..92923b44cff 100644
--- a/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt
+++ b/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class A {
   fun f() : A
 }
diff --git a/idea/idea-completion/testData/basic/common/ObjectRedeclaration1.kt b/idea/idea-completion/testData/basic/common/ObjectRedeclaration1.kt
index 878e9978c3d..ed4a1fe2b26 100644
--- a/idea/idea-completion/testData/basic/common/ObjectRedeclaration1.kt
+++ b/idea/idea-completion/testData/basic/common/ObjectRedeclaration1.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 object A {
   fun f() : S<caret>
 }
diff --git a/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt b/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt
index 414eb30ff14..6fddff733e4 100644
--- a/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt
+++ b/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 object A {
   fun f() : S
 }
diff --git a/idea/idea-completion/testData/basic/common/annotations/ParameterAnnotation6.kt b/idea/idea-completion/testData/basic/common/annotations/ParameterAnnotation6.kt
index 0832aa3d159..9269e306538 100644
--- a/idea/idea-completion/testData/basic/common/annotations/ParameterAnnotation6.kt
+++ b/idea/idea-completion/testData/basic/common/annotations/ParameterAnnotation6.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 val v = 1
 
 enum class class InlineOption {
diff --git a/idea/idea-completion/testData/basic/common/namedArguments/InParameterExpression.kt b/idea/idea-completion/testData/basic/common/namedArguments/InParameterExpression.kt
index 643ef3cb3f5..f36b631a0df 100644
--- a/idea/idea-completion/testData/basic/common/namedArguments/InParameterExpression.kt
+++ b/idea/idea-completion/testData/basic/common/namedArguments/InParameterExpression.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 val paramTest = 12
 
 fun small(paramFirst: Int, paramSecond: Int) {
diff --git a/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionExplicitReceiver.kt b/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionExplicitReceiver.kt
index 711e59e840b..bf5c93baf06 100644
--- a/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionExplicitReceiver.kt
+++ b/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionExplicitReceiver.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun Any.anyFun() {}
 val Any.anyVal: Int get() = 10
 
diff --git a/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionImplicitReceiver.kt b/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionImplicitReceiver.kt
index e2034958862..e7d4c06da16 100644
--- a/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionImplicitReceiver.kt
+++ b/idea/idea-completion/testData/basic/common/primitiveCompletion/extensionPropertyAndFunctionImplicitReceiver.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun Any.anyFun() {}
 val Any.anyVal: Int get() = 10
 
diff --git a/idea/idea-completion/testData/basic/common/primitiveCompletion/topLevelVariablesAndFunctions.kt b/idea/idea-completion/testData/basic/common/primitiveCompletion/topLevelVariablesAndFunctions.kt
index a2ba6a24ce8..ef2bdbabfe9 100644
--- a/idea/idea-completion/testData/basic/common/primitiveCompletion/topLevelVariablesAndFunctions.kt
+++ b/idea/idea-completion/testData/basic/common/primitiveCompletion/topLevelVariablesAndFunctions.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun aa() {}
 val aaa = 10
 
diff --git a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThis.kt b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThis.kt
index 28d045b0d23..95096adf998 100644
--- a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThis.kt
+++ b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThis.kt
@@ -1,4 +1,5 @@
-class A<in I> {
+// FIR_COMPARISON
+`class A<in I> {
     private val bar: I
 
     private fun foo(): I = null!!
diff --git a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisInSpecialScope.kt b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisInSpecialScope.kt
index 18d6fd2b786..9505f026e5b 100644
--- a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisInSpecialScope.kt
+++ b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisInSpecialScope.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class A<in I> {
     private val bar: I
 
diff --git a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithReceiver2.kt b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithReceiver2.kt
index 9ee6e697f97..85ed8f58962 100644
--- a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithReceiver2.kt
+++ b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithReceiver2.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class A<in I> {
     private val bar: I
 
diff --git a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithThis.kt b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithThis.kt
index 68d4475abed..56d11139f31 100644
--- a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithThis.kt
+++ b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithThis.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class A<in I> {
     private val bar: I
 
diff --git a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithWrongThis.kt b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithWrongThis.kt
index 5f18a7eb519..e427aa3fa2a 100644
--- a/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithWrongThis.kt
+++ b/idea/idea-completion/testData/basic/common/visibility/VisibilityPrivateToThisWithWrongThis.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class A<in I> {
     private val bar: I
 
diff --git a/idea/idea-completion/testData/basic/java/NonImportedPrefixMatching1.kt b/idea/idea-completion/testData/basic/java/NonImportedPrefixMatching1.kt
index 5e0e8593cb0..89cdfdf4c85 100644
--- a/idea/idea-completion/testData/basic/java/NonImportedPrefixMatching1.kt
+++ b/idea/idea-completion/testData/basic/java/NonImportedPrefixMatching1.kt
@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Host
 
 fun foo(): Ho<caret>