diff --git a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/intermediate/OnceExpressionValue.kt b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/intermediate/OnceExpressionValue.kt
index 3f081192306..8a690050153 100644
--- a/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/intermediate/OnceExpressionValue.kt
+++ b/compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/intermediate/OnceExpressionValue.kt
@@ -16,17 +16,12 @@
 
 package org.jetbrains.kotlin.psi2ir.intermediate
 
-import org.jetbrains.kotlin.ir.assertDetached
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.psi2ir.generators.CallGenerator
 import org.jetbrains.kotlin.types.KotlinType
 
 class OnceExpressionValue(val irExpression: IrExpression) : IntermediateValue {
-    init {
-        irExpression.assertDetached()
-    }
-
     private var instantiated = false
 
     override fun load(): IrExpression {
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/IrElement.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/IrElement.kt
index c1f04856961..7a2c3183fb6 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/IrElement.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/IrElement.kt
@@ -65,14 +65,6 @@ inline fun <T : IrElement> T.replaceWith(transformation: (T) -> IrElement) {
     }
 }
 
-fun IrElement.assertChild(child: IrElement) {
-    assert(getChild(child.slot) == child) { "$this: Invalid child: $child" }
-}
-
-fun IrElement.assertDetached() {
-    assert(parent == null && slot == DETACHED_SLOT) { "$this: should be detached" }
-}
-
 fun IrElement.throwNoSuchSlot(slot: Int): Nothing =
         throw AssertionError("${this.render()}: no such slot $slot")
 
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrAnonymousInitializerImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrAnonymousInitializerImpl.kt
index f4024f991d5..f83aa03da2b 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrAnonymousInitializerImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrAnonymousInitializerImpl.kt
@@ -34,7 +34,6 @@ class IrAnonymousInitializerImpl(
     override var body: IrBlockBody
         get() = bodyImpl!!
         set(value) {
-            value.assertDetached()
             bodyImpl?.detach()
             bodyImpl = value
             value.setTreeLocation(this, ANONYMOUS_INITIALIZER_BODY_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
index 62c569110e4..a38e17b8cb9 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
@@ -33,7 +33,6 @@ class IrClassImpl(
     override val members: MutableList<IrDeclaration> = ArrayList()
 
     fun addMember(member: IrDeclaration) {
-        member.assertDetached()
         member.setTreeLocation(this, members.size)
         members.add(member)
     }
@@ -43,7 +42,6 @@ class IrClassImpl(
 
 
     override fun replaceChild(slot: Int, newChild: IrElement) {
-        newChild.assertDetached()
         members.getOrNull(slot)?.detach() ?: throwNoSuchSlot(slot)
         members[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDelegatedPropertyImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDelegatedPropertyImpl.kt
index cf025c0439c..9fa0f87253e 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDelegatedPropertyImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrDelegatedPropertyImpl.kt
@@ -43,7 +43,6 @@ class IrDelegatedPropertyImpl(
     override var delegate: IrSimpleProperty
         get() = delegateImpl!!
         set(value) {
-            value.assertDetached()
             delegateImpl?.detach()
             delegateImpl = value
             value.setTreeLocation(this, DELEGATE_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrEnumEntryImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrEnumEntryImpl.kt
index febcce1364f..2179524abf6 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrEnumEntryImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrEnumEntryImpl.kt
@@ -32,7 +32,6 @@ class IrEnumEntryImpl(
 ) : IrDeclarationBase(startOffset, endOffset, origin), IrEnumEntry {
     override var correspondingClass: IrClass? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, ENUM_ENTRY_CLASS_SLOT)
@@ -42,7 +41,6 @@ class IrEnumEntryImpl(
     override var initializerExpression: IrExpression
         get() = initializerExpressionImpl!!
         set(value) {
-            value.assertDetached()
             initializerExpressionImpl?.detach()
             initializerExpressionImpl = value
             value.setTreeLocation(this, ENUM_ENTRY_INITIALIZER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt
index d9de588d64b..b1e974821f8 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt
@@ -39,7 +39,6 @@ class IrFileImpl(
     override val declarations: MutableList<IrDeclaration> = ArrayList()
 
     fun addDeclaration(declaration: IrDeclaration) {
-        declaration.assertDetached()
         declaration.setTreeLocation(this, declarations.size)
         declarations.add(declaration)
     }
@@ -48,7 +47,6 @@ class IrFileImpl(
             declarations.getOrNull(slot)
 
     override fun replaceChild(slot: Int, newChild: IrElement) {
-        newChild.assertDetached()
         declarations.getOrNull(slot)?.detach() ?: throwNoSuchSlot(slot)
         declarations[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionBase.kt
index 0f8bacb6b25..a2244f9d314 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionBase.kt
@@ -17,7 +17,6 @@
 package org.jetbrains.kotlin.ir.declarations.impl
 
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
-import org.jetbrains.kotlin.ir.assertDetached
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.detach
@@ -36,7 +35,6 @@ abstract class IrFunctionBase(
             defaults[parameter]
 
     override fun putDefault(parameter: ValueParameterDescriptor, expressionBody: IrExpressionBody) {
-        expressionBody.assertDetached()
         defaults[parameter]?.detach()
         defaults[parameter] = expressionBody
         expressionBody.setTreeLocation(this, parameter.index)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrGeneralFunctionBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrGeneralFunctionBase.kt
index 63bc1baff65..30be3ee43e5 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrGeneralFunctionBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrGeneralFunctionBase.kt
@@ -39,7 +39,6 @@ abstract class IrGeneralFunctionBase(
 
     final override var body: IrBody? = null
         set(newValue) {
-            newValue?.assertDetached()
             field?.detach()
             field = newValue
             newValue?.setTreeLocation(this, FUNCTION_BODY_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrLocalDelegatedPropertyImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrLocalDelegatedPropertyImpl.kt
index f6a418731f8..82134352b14 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrLocalDelegatedPropertyImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrLocalDelegatedPropertyImpl.kt
@@ -45,7 +45,6 @@ class IrLocalDelegatedPropertyImpl(
     override var delegate: IrVariable
         get() = delegateImpl!!
         set(value) {
-            value.assertDetached()
             delegateImpl?.detach()
             delegateImpl = value
             value.setTreeLocation(this, DELEGATE_SLOT)
@@ -55,7 +54,6 @@ class IrLocalDelegatedPropertyImpl(
     override var getter: IrLocalPropertyAccessor
         get() = getterImpl!!
         set(value) {
-            value.assertDetached()
             getterImpl?.detach()
             getterImpl = value
             value.setTreeLocation(this, PROPERTY_GETTER_SLOT)
@@ -63,7 +61,6 @@ class IrLocalDelegatedPropertyImpl(
 
     override var setter: IrLocalPropertyAccessor? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, PROPERTY_SETTER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrModuleFragmentImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrModuleFragmentImpl.kt
index 3da80365a5c..f20b1f54abb 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrModuleFragmentImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrModuleFragmentImpl.kt
@@ -17,13 +17,10 @@
 package org.jetbrains.kotlin.ir.declarations.impl
 
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
-import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.assertDetached
+import org.jetbrains.kotlin.ir.*
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
-import org.jetbrains.kotlin.ir.detach
-import org.jetbrains.kotlin.ir.throwNoSuchSlot
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import java.util.*
 
@@ -38,13 +35,11 @@ class IrModuleFragmentImpl(
     override val files: MutableList<IrFile> = ArrayList()
 
     fun addFile(file: IrFile) {
-        file.assertDetached()
         file.setTreeLocation(this, files.size)
         files.add(file)
     }
 
     fun addAll(newFiles: List<IrFile>) {
-        newFiles.forEach { it.assertDetached() }
         val originalSize = files.size
         files.addAll(newFiles)
         newFiles.forEachIndexed { i, irFile ->  irFile.setTreeLocation(this, originalSize + i) }
@@ -54,8 +49,8 @@ class IrModuleFragmentImpl(
             files.getOrNull(slot)
 
     override fun replaceChild(slot: Int, newChild: IrElement) {
-        newChild.assertDetached()
         files.getOrNull(slot)?.detach() ?: throwNoSuchSlot(slot)
+        files[slot] = newChild.assertCast()
     }
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrPropertyBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrPropertyBase.kt
index b0b0fdedd23..f3e78fc0be5 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrPropertyBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrPropertyBase.kt
@@ -32,7 +32,6 @@ abstract class IrPropertyBase(
 ) : IrDeclarationBase(startOffset, endOffset, origin), IrProperty {
     override var getter: IrPropertyGetter? = null
         set(newGetter) {
-            newGetter?.assertDetached()
             field?.detach()
             field = newGetter
             newGetter?.setTreeLocation(this, PROPERTY_GETTER_SLOT)
@@ -40,7 +39,6 @@ abstract class IrPropertyBase(
 
     override var setter: IrPropertySetter? = null
         set(newSetter) {
-            newSetter?.assertDetached()
             field?.detach()
             field = newSetter
             newSetter?.setTreeLocation(this, PROPERTY_SETTER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrSimplePropertyImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrSimplePropertyImpl.kt
index 348340ac0d0..3be639bb5dc 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrSimplePropertyImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrSimplePropertyImpl.kt
@@ -32,7 +32,6 @@ class IrSimplePropertyImpl(
 ) : IrPropertyBase(startOffset, endOffset, origin, descriptor), IrSimpleProperty {
     override var initializer: IrBody? = valueInitializer
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, INITIALIZER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrVariableImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrVariableImpl.kt
index bbbed51cc34..35bd5eec784 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrVariableImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrVariableImpl.kt
@@ -42,7 +42,6 @@ class IrVariableImpl(
 
     override var initializer: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, INITIALIZER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBackingFieldExpressionBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBackingFieldExpressionBase.kt
index 0df15e43bc8..f48a6bd6cfc 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBackingFieldExpressionBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBackingFieldExpressionBase.kt
@@ -34,7 +34,6 @@ abstract class IrBackingFieldExpressionBase(
 ) : IrDeclarationReferenceBase<PropertyDescriptor>(startOffset, endOffset, type, descriptor), IrBackingFieldExpression {
     override final var receiver: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, BACKING_FIELD_RECEIVER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt
index 7abab877499..a13876a6e32 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt
@@ -25,7 +25,6 @@ class IrBlockBodyImpl(startOffset: Int, endOffset: Int) : IrElementBase(startOff
     override val statements: MutableList<IrStatement> = ArrayList()
 
     fun addStatement(statement: IrStatement) {
-        statement.assertDetached()
         statement.setTreeLocation(this, statements.size)
         statements.add(statement)
     }
@@ -36,7 +35,6 @@ class IrBlockBodyImpl(startOffset: Int, endOffset: Int) : IrElementBase(startOff
     override fun replaceChild(slot: Int, newChild: IrElement) {
         if (slot < 0 || slot >= statements.size) throwNoSuchSlot(slot)
 
-        newChild.assertDetached()
         statements[slot].detach()
         statements[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrContainerExpressionBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrContainerExpressionBase.kt
index 2191e669196..b7721b242e5 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrContainerExpressionBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrContainerExpressionBase.kt
@@ -27,13 +27,11 @@ abstract class IrContainerExpressionBase(startOffset: Int, endOffset: Int, type:
     override val statements: MutableList<IrStatement> = ArrayList(2)
 
     fun addStatement(statement: IrStatement) {
-        statement.assertDetached()
         statement.setTreeLocation(this, statements.size)
         statements.add(statement)
     }
 
     fun addAll(newStatements: List<IrStatement>) {
-        newStatements.forEach { it.assertDetached() }
         val originalSize = this.statements.size
         this.statements.addAll(newStatements)
         newStatements.forEachIndexed { i, irStatement ->
@@ -47,7 +45,6 @@ abstract class IrContainerExpressionBase(startOffset: Int, endOffset: Int, type:
     override fun replaceChild(slot: Int, newChild: IrElement) {
         if (slot < 0 || slot >= statements.size) throwNoSuchSlot(slot)
 
-        newChild.assertDetached()
         statements[slot].detach()
         statements[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrErrorCallExpressionImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrErrorCallExpressionImpl.kt
index 4ffc869f8e9..c3c78ddb119 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrErrorCallExpressionImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrErrorCallExpressionImpl.kt
@@ -31,7 +31,6 @@ class IrErrorCallExpressionImpl(
 ) : IrExpressionBase(startOffset, endOffset, type), IrErrorCallExpression {
     override var explicitReceiver: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, DISPATCH_RECEIVER_SLOT)
@@ -40,7 +39,6 @@ class IrErrorCallExpressionImpl(
     override val arguments: MutableList<IrExpression> = SmartList()
 
     fun addArgument(argument: IrExpression) {
-        argument.assertDetached()
         argument.setTreeLocation(this, arguments.size)
         arguments.add(argument)
     }
@@ -60,7 +58,6 @@ class IrErrorCallExpressionImpl(
     override fun replaceChild(slot: Int, newChild: IrElement) {
         if (slot < 0 || slot >= arguments.size) throwNoSuchSlot(slot)
 
-        newChild.assertDetached()
         arguments[slot].detach()
         arguments[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt
index 76959147878..0b83613c367 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt
@@ -30,7 +30,6 @@ class IrExpressionBodyImpl(startOffset: Int, endOffset: Int) : IrElementBase(sta
     override var expression: IrExpression
         get() = expressionImpl!!
         set(newValue) {
-            newValue.assertDetached()
             expressionImpl?.detach()
             expressionImpl = newValue
             newValue.setTreeLocation(this, CHILD_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGeneralCallBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGeneralCallBase.kt
index 0564d0222e3..55a8afcb44e 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGeneralCallBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGeneralCallBase.kt
@@ -18,7 +18,6 @@ package org.jetbrains.kotlin.ir.expressions.impl
 
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.assertCast
-import org.jetbrains.kotlin.ir.assertDetached
 import org.jetbrains.kotlin.ir.detach
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrGeneralCall
@@ -44,7 +43,6 @@ abstract class IrGeneralCallBase(
         if (index >= argumentsByParameterIndex.size) {
             throw AssertionError("$this: No such argument slot: $index")
         }
-        valueArgument?.assertDetached()
         argumentsByParameterIndex[index]?.detach()
         argumentsByParameterIndex[index] = valueArgument
         valueArgument?.setTreeLocation(this, index)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGetClassImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGetClassImpl.kt
index 4ba1ad2d6d1..d13c63c461e 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGetClassImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrGetClassImpl.kt
@@ -32,7 +32,6 @@ class IrGetClassImpl(startOffset: Int, endOffset: Int, type: KotlinType) : IrExp
     override var argument: IrExpression
         get() = argumentImpl!!
         set(value) {
-            value.assertDetached()
             argumentImpl?.detach()
             argumentImpl = value
             value.setTreeLocation(this, CHILD_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrIfThenElseImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrIfThenElseImpl.kt
index 4c4f5e44187..c694655d621 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrIfThenElseImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrIfThenElseImpl.kt
@@ -20,7 +20,6 @@ import org.jetbrains.kotlin.ir.*
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrOperator
 import org.jetbrains.kotlin.ir.expressions.IrWhen
-import org.jetbrains.kotlin.ir.expressions.impl.IrExpressionBase
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.types.KotlinType
 
@@ -56,7 +55,6 @@ class IrIfThenElseImpl(
     var condition: IrExpression
         get() = conditionImpl!!
         set(value) {
-            value.assertDetached()
             value.detach()
             conditionImpl = value
             value.setTreeLocation(this, IF_CONDITION_SLOT)
@@ -66,7 +64,6 @@ class IrIfThenElseImpl(
     var thenBranch: IrExpression
         get() = thenBranchImpl!!
         set(value) {
-            value.assertDetached()
             value.detach()
             thenBranchImpl = value
             value.setTreeLocation(this, IF_THEN_SLOT)
@@ -74,7 +71,6 @@ class IrIfThenElseImpl(
 
     override var elseBranch: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             value?.detach()
             field = value
             value?.setTreeLocation(this, IF_ELSE_SLOT)
@@ -89,7 +85,6 @@ class IrIfThenElseImpl(
             }
 
     override fun replaceChild(slot: Int, newChild: IrElement) {
-        newChild.assertDetached()
         when (slot) {
             IF_CONDITION_SLOT ->
                 condition = newChild.assertCast()
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrLoopBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrLoopBase.kt
index bfa40f5c67d..5b74747952f 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrLoopBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrLoopBase.kt
@@ -35,7 +35,6 @@ abstract class IrLoopBase(
     override var condition: IrExpression
         get() = conditionImpl!!
         set(value) {
-            value.assertDetached()
             conditionImpl?.detach()
             conditionImpl = value
             value.setTreeLocation(this, LOOP_CONDITION_SLOT)
@@ -43,7 +42,6 @@ abstract class IrLoopBase(
 
     override var body: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, LOOP_BODY_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrMemberAccessExpressionBase.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrMemberAccessExpressionBase.kt
index 13ef0c30faf..0a3ebee3ad8 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrMemberAccessExpressionBase.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrMemberAccessExpressionBase.kt
@@ -30,7 +30,6 @@ abstract class IrMemberAccessExpressionBase(
 ) : IrExpressionBase(startOffset, endOffset, type), IrMemberAccessExpression {
     override var dispatchReceiver: IrExpression? = null
         set(newReceiver) {
-            newReceiver?.assertDetached()
             field?.detach()
             field = newReceiver
             newReceiver?.setTreeLocation(this, DISPATCH_RECEIVER_SLOT)
@@ -38,7 +37,6 @@ abstract class IrMemberAccessExpressionBase(
 
     override var extensionReceiver: IrExpression? = null
         set(newReceiver) {
-            newReceiver?.assertDetached()
             field?.detach()
             field = newReceiver
             newReceiver?.setTreeLocation(this, EXTENSION_RECEIVER_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPrimitiveCall.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPrimitiveCall.kt
index 061c5dd7574..154f3443f1e 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPrimitiveCall.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPrimitiveCall.kt
@@ -93,7 +93,6 @@ class IrUnaryPrimitiveImpl private constructor(
     var argument: IrExpression
         get() = argumentImpl!!
         set(value) {
-            value.assertDetached()
             argumentImpl?.detach()
             argumentImpl = value
             value.setTreeLocation(this, ARGUMENT0_SLOT)
@@ -139,7 +138,6 @@ class IrBinaryPrimitiveImpl(
     var argument0: IrExpression
         get() = argument0Impl!!
         set(value) {
-            value.assertDetached()
             argument0Impl?.detach()
             argument0Impl = value
             value.setTreeLocation(this, ARGUMENT0_SLOT)
@@ -149,7 +147,6 @@ class IrBinaryPrimitiveImpl(
     var argument1: IrExpression
         get() = argument1Impl!!
         set(value) {
-            value.assertDetached()
             argument1Impl?.detach()
             argument1Impl = value
             value.setTreeLocation(this, ARGUMENT1_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPropertyAccessorCall.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPropertyAccessorCall.kt
index ba999abaf6e..76e2af4631c 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPropertyAccessorCall.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrPropertyAccessorCall.kt
@@ -98,7 +98,6 @@ class IrSetterCallImpl(
     override fun putArgument(index: Int, valueArgument: IrExpression?) {
         if (index != SETTER_ARGUMENT_INDEX) return
         argumentImpl?.detach()
-        valueArgument?.assertDetached()
         argumentImpl = valueArgument
         valueArgument?.setTreeLocation(this, SETTER_ARGUMENT_INDEX)
     }
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrReturnImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrReturnImpl.kt
index c8fdb3af06d..f01ca05f425 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrReturnImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrReturnImpl.kt
@@ -42,7 +42,6 @@ class IrReturnImpl(
 
     override var value: IrExpression? = null
         set(newValue) {
-            newValue?.assertDetached()
             field?.detach()
             field = newValue
             newValue?.setTreeLocation(this, CHILD_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetBackingFieldImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetBackingFieldImpl.kt
index 4ffcd98d7d9..c753464d1b6 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetBackingFieldImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetBackingFieldImpl.kt
@@ -50,7 +50,6 @@ class IrSetBackingFieldImpl(
     override var value: IrExpression
         get() = valueImpl!!
         set(value) {
-            value.assertDetached()
             valueImpl?.detach()
             valueImpl = value
             value.setTreeLocation(this, CHILD_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetVariableImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetVariableImpl.kt
index 8253e7735c1..2fa20a8528a 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetVariableImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSetVariableImpl.kt
@@ -45,7 +45,6 @@ class IrSetVariableImpl(
     override var value: IrExpression
         get() = valueImpl!!
         set(value) {
-            value.assertDetached()
             valueImpl?.detach()
             valueImpl = value
             value.setTreeLocation(this, ARGUMENT0_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSpreadElementImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSpreadElementImpl.kt
index 1d7f7812c8e..f8dfef5efe5 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSpreadElementImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSpreadElementImpl.kt
@@ -33,7 +33,6 @@ class IrSpreadElementImpl(
     override var expression: IrExpression
         get() = expressionImpl!!
         set(value) {
-            value.assertDetached()
             expressionImpl?.detach()
             expressionImpl = value
             value.setTreeLocation(this, CHILD_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrStringConcatenationImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrStringConcatenationImpl.kt
index c76e0f77b22..c9ce78ceab8 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrStringConcatenationImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrStringConcatenationImpl.kt
@@ -32,7 +32,6 @@ class IrStringConcatenationImpl(
     override val arguments: MutableList<IrExpression> = ArrayList()
 
     override fun addArgument(argument: IrExpression) {
-        argument.assertDetached()
         argument.setTreeLocation(this, arguments.size)
         arguments.add(argument)
     }
@@ -43,7 +42,6 @@ class IrStringConcatenationImpl(
     override fun replaceChild(slot: Int, newChild: IrElement) {
         if (slot < 0 || slot >= arguments.size) throwNoSuchSlot(slot)
 
-        newChild.assertDetached()
         arguments[slot].detach()
         arguments[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrThrowImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrThrowImpl.kt
index 7033ed26e39..a310284a1d4 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrThrowImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrThrowImpl.kt
@@ -41,7 +41,6 @@ class IrThrowImpl(
     override var value: IrExpression
         get() = valueImpl!!
         set(newValue) {
-            newValue.assertDetached()
             valueImpl?.detach()
             valueImpl = newValue
             newValue.setTreeLocation(this, CHILD_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTryCatchImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTryCatchImpl.kt
index a4cfac61bf5..f2fc11806f4 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTryCatchImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTryCatchImpl.kt
@@ -34,7 +34,6 @@ class IrTryCatchImpl(
     override var tryResult: IrExpression
         get() = tryResultImpl!!
         set(value) {
-            value.assertDetached()
             tryResultImpl?.detach()
             tryResultImpl = value
             value.setTreeLocation(this, TRY_RESULT_SLOT)
@@ -46,7 +45,6 @@ class IrTryCatchImpl(
     override val catchClausesCount: Int get() = catchClauseResults.size
 
     fun addCatchClause(parameter: VariableDescriptor, result: IrExpression) {
-        result.assertDetached()
         result.setTreeLocation(this, catchClausesCount)
         catchClauseParameters.add(parameter)
         catchClauseResults.add(result)
@@ -60,7 +58,6 @@ class IrTryCatchImpl(
 
     override var finallyExpression: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             field?.detach()
             field = value
             value?.setTreeLocation(this, FINALLY_EXPRESSION_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTypeOperatorCallImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTypeOperatorCallImpl.kt
index 2cd3eb57994..125d2722b48 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTypeOperatorCallImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrTypeOperatorCallImpl.kt
@@ -46,7 +46,6 @@ class IrTypeOperatorCallImpl(
     override var argument: IrExpression
         get() = argumentImpl!!
         set(value) {
-            value.assertDetached()
             argumentImpl?.detach()
             argumentImpl = value
             value.setTreeLocation(this, ARGUMENT0_SLOT)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrVarargImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrVarargImpl.kt
index 18435bc6cbe..65e28aad647 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrVarargImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrVarargImpl.kt
@@ -33,7 +33,6 @@ class IrVarargImpl(
     override val elements: MutableList<IrVarargElement> = SmartList()
 
     fun addElement(varargElement: IrVarargElement) {
-        varargElement.assertDetached()
         varargElement.setTreeLocation(this, elements.size)
         elements.add(varargElement)
     }
@@ -44,7 +43,6 @@ class IrVarargImpl(
     override fun replaceChild(slot: Int, newChild: IrElement) {
         if (slot < 0 || slot >= elements.size) throwNoSuchSlot(slot)
 
-        newChild.assertDetached()
         elements[slot].detach()
         elements[slot] = newChild.assertCast()
         newChild.setTreeLocation(this, slot)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrWhenImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrWhenImpl.kt
index 226325c1b50..dae9070178f 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrWhenImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrWhenImpl.kt
@@ -34,8 +34,6 @@ class IrWhenImpl(
     private val branchParts = ArrayList<IrExpression>()
 
     fun addBranch(condition: IrExpression, result: IrExpression) {
-        condition.assertDetached()
-        result.assertDetached()
         condition.setTreeLocation(this, branchParts.size)
         branchParts.add(condition)
         result.setTreeLocation(this, branchParts.size)
@@ -44,7 +42,6 @@ class IrWhenImpl(
 
     override var elseBranch: IrExpression? = null
         set(value) {
-            value?.assertDetached()
             value?.detach()
             field = value
             value?.setTreeLocation(this, IF_ELSE_SLOT)
@@ -61,7 +58,6 @@ class IrWhenImpl(
         when (slot) {
             IF_ELSE_SLOT -> elseBranch = newChild.assertCast()
             in branchParts.indices -> {
-                newChild.assertDetached()
                 branchParts[slot].detach()
                 branchParts[slot] = newChild.assertCast()
                 newChild.setTreeLocation(this, slot)