Refactoring.

'if' expressions (represented as 'when' without subject).

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/IrUtils.kt

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.psi2ir
 
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.ir.declarations.IrVariable
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.types.KotlinType
@@ -24,6 +25,8 @@ import org.jetbrains.kotlin.types.isNullabilityFlexible
 
 fun IrExpression.toExpectedType(expectedType: KotlinType?): IrExpression {
     if (expectedType == null) return this
+    if (KotlinBuiltIns.isUnit(expectedType)) return this // TODO expose coercion to Unit in IR?
+
     val valueType = type ?: throw AssertionError("expectedType != null, valueType == null: $this")
 
     if (valueType.isNullabilityFlexible() && !expectedType.isMarkedNullable) {

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/Psi2IrTranslator.kt

@@ -20,8 +20,8 @@ import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrModule
 import org.jetbrains.kotlin.psi.KtFile
-import org.jetbrains.kotlin.psi2ir.generators.IrGeneratorContext
-import org.jetbrains.kotlin.psi2ir.generators.IrModuleGenerator
+import org.jetbrains.kotlin.psi2ir.generators.GeneratorContext
+import org.jetbrains.kotlin.psi2ir.generators.ModuleGenerator
 import org.jetbrains.kotlin.psi2ir.transformations.foldStringConcatenation
 import org.jetbrains.kotlin.psi2ir.transformations.inlineDesugaredBlocks
 import org.jetbrains.kotlin.resolve.BindingContext
@@ -33,8 +33,8 @@ class Psi2IrTranslator(val configuration: Configuration = Configuration()) {
     )
 
     fun generateModule(moduleDescriptor: ModuleDescriptor, ktFiles: List<KtFile>, bindingContext: BindingContext): IrModule {
-        val irGeneratorContext = IrGeneratorContext(moduleDescriptor, bindingContext)
-        val irModule = IrModuleGenerator(irGeneratorContext).generateModule(ktFiles)
+        val irGeneratorContext = GeneratorContext(moduleDescriptor, bindingContext)
+        val irModule = ModuleGenerator(irGeneratorContext).generateModule(ktFiles)
         postprocess(irModule)
         return irModule
     }

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

@@ -22,7 +22,7 @@ import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
-import org.jetbrains.kotlin.psi2ir.generators.values.IrVariableLValue
+import org.jetbrains.kotlin.psi2ir.generators.values.VariableLValue
 import org.jetbrains.kotlin.psi2ir.generators.values.IrValue
 import org.jetbrains.kotlin.psi2ir.generators.values.createRematerializableValue
 import org.jetbrains.kotlin.psi2ir.toExpectedType
@@ -32,12 +32,12 @@ import org.jetbrains.kotlin.resolve.scopes.receivers.*
 import org.jetbrains.kotlin.types.KotlinType
 import java.util.*
 
-class IrCallGenerator(val irStatementGenerator: IrStatementGenerator) : IrGenerator {
-    override val context: IrGeneratorContext get() =
-            irStatementGenerator.context
+class CallGenerator(val statementGenerator: StatementGenerator) : IrGenerator {
+    override val context: GeneratorContext get() =
+            statementGenerator.context
 
-    private val temporaryVariableFactory: IrTemporaryVariableFactory get() =
-            irStatementGenerator.temporaryVariableFactory
+    private val temporaryVariableFactory: TemporaryVariableFactory get() =
+            statementGenerator.temporaryVariableFactory
 
     private val expressionValues = HashMap<KtExpression, IrValue>()
     private val receiverValues = HashMap<ReceiverValue, IrValue>()
@@ -51,7 +51,7 @@ class IrCallGenerator(val irStatementGenerator: IrStatementGenerator) : IrGenera
         }
 
         val irTmpVar = temporaryVariableFactory.createTemporaryVariable(irExpression, nameHint)
-        putValue(ktExpression, IrVariableLValue(irTmpVar))
+        putValue(ktExpression, VariableLValue(irTmpVar))
         return irTmpVar
     }
 
@@ -63,7 +63,7 @@ class IrCallGenerator(val irStatementGenerator: IrStatementGenerator) : IrGenera
         }
 
         val irTmpVar = temporaryVariableFactory.createTemporaryVariable(irExpression, valueParameterDescriptor.name.asString())
-        putValue(valueParameterDescriptor, IrVariableLValue(irTmpVar))
+        putValue(valueParameterDescriptor, VariableLValue(irTmpVar))
         return irTmpVar
     }
 
@@ -249,6 +249,6 @@ class IrCallGenerator(val irStatementGenerator: IrStatementGenerator) : IrGenera
             }
 
     private fun generateExpression(ktExpression: KtExpression): IrExpression =
-            expressionValues[ktExpression]?.load() ?: irStatementGenerator.generateExpression(ktExpression)
+            expressionValues[ktExpression]?.load() ?: statementGenerator.generateExpression(ktExpression)
 
 }

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

@@ -28,7 +28,7 @@ import org.jetbrains.kotlin.utils.SmartList
 import org.jetbrains.kotlin.utils.addIfNotNull
 import org.jetbrains.kotlin.utils.addToStdlib.singletonList
 
-class IrDeclarationGenerator(override val context: IrGeneratorContext) : IrGenerator {
+class DeclarationGenerator(override val context: GeneratorContext) : IrGenerator {
     fun generateAnnotationEntries(annotationEntries: List<KtAnnotationEntry>) {
         // TODO create IrAnnotation's for each KtAnnotationEntry
     }
@@ -140,7 +140,7 @@ class IrDeclarationGenerator(override val context: IrGeneratorContext) : IrGener
     }
 
     private fun generateExpressionWithinContext(ktExpression: KtExpression, scopeOwner: DeclarationDescriptor): IrExpression =
-            IrStatementGenerator(context, scopeOwner, IrTemporaryVariableFactory(scopeOwner))
+            StatementGenerator(context, scopeOwner, TemporaryVariableFactory(scopeOwner))
                     .generateExpression(ktExpression)
                     .toExpectedType(getExpectedTypeForLastInferredCall(ktExpression))
 

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

@@ -33,7 +33,7 @@ import org.jetbrains.kotlin.types.typeUtil.makeNullable
 import org.jetbrains.kotlin.util.slicedMap.ReadOnlySlice
 
 interface IrGenerator {
-    val context: IrGeneratorContext
+    val context: GeneratorContext
 }
 
 fun <K, V : Any> IrGenerator.get(slice: ReadOnlySlice<K, V>, key: K): V? =

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

@@ -23,7 +23,7 @@ import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi2ir.PsiSourceManager
 import org.jetbrains.kotlin.resolve.BindingContext
 
-class IrGeneratorContext(
+class GeneratorContext(
         val moduleDescriptor: ModuleDescriptor,
         val bindingContext: BindingContext
 ) {

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

@@ -20,9 +20,9 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.BindingContext
 
-class IrModuleGenerator(override val context: IrGeneratorContext) : IrGenerator {
+class ModuleGenerator(override val context: GeneratorContext) : IrGenerator {
     fun generateModule(ktFiles: List<KtFile>): IrModule {
-        val irDeclarationGenerator = IrDeclarationGenerator(context)
+        val irDeclarationGenerator = DeclarationGenerator(context)
 
         val irModule = IrModuleImpl(context.moduleDescriptor)
         for (ktFile in ktFiles) {

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

@@ -20,12 +20,10 @@ import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.impl.LocalVariableDescriptor
+import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.lexer.KtTokens
-import org.jetbrains.kotlin.psi.KtArrayAccessExpression
-import org.jetbrains.kotlin.psi.KtBinaryExpression
-import org.jetbrains.kotlin.psi.KtExpression
-import org.jetbrains.kotlin.psi.KtPrefixExpression
+import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.psi2ir.generators.values.*
@@ -36,8 +34,8 @@ import org.jetbrains.kotlin.resolve.calls.callUtil.isSafeCall
 import org.jetbrains.kotlin.types.typeUtil.makeNullable
 
 
-class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerator): IrGenerator {
-    override val context: IrGeneratorContext get() = irStatementGenerator.context
+class OperatorExpressionGenerator(val statementGenerator: StatementGenerator): IrGenerator {
+    override val context: GeneratorContext get() = statementGenerator.context
 
     fun generatePrefixExpression(expression: KtPrefixExpression): IrExpression {
         val ktOperator = expression.operationReference.getReferencedNameElementType()
@@ -50,6 +48,10 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
         }
     }
 
+    fun generatePostfixExpression(expression: KtPostfixExpression): IrExpression {
+        TODO("not implemented")
+    }
+
     fun generateBinaryExpression(expression: KtBinaryExpression): IrExpression {
         val ktOperator = expression.operationReference.getReferencedNameElementType()
         if (ktOperator == KtTokens.IDENTIFIER) {
@@ -77,8 +79,8 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
         // TODO desugar '?:' to 'if'?
         val specialCallForElvis = getResolvedCall(expression)!!
         val returnType = specialCallForElvis.resultingDescriptor.returnType!!
-        val irArgument0 = irStatementGenerator.generateExpression(expression.left!!).toExpectedType(returnType.makeNullable())
-        val irArgument1 = irStatementGenerator.generateExpression(expression.right!!).toExpectedType(returnType)
+        val irArgument0 = statementGenerator.generateExpression(expression.left!!).toExpectedType(returnType.makeNullable())
+        val irArgument1 = statementGenerator.generateExpression(expression.right!!).toExpectedType(returnType)
         return IrBinaryOperatorExpressionImpl(
                 expression.startOffset, expression.endOffset, returnType,
                 IrOperator.ELVIS, null, irArgument0, irArgument1
@@ -86,8 +88,8 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
     }
 
     private fun generateBinaryBooleanOperator(expression: KtBinaryExpression, irOperator: IrBinaryOperator): IrExpression {
-        val irArgument0 = irStatementGenerator.generateExpression(expression.left!!).toExpectedType(context.builtIns.booleanType)
-        val irArgument1 = irStatementGenerator.generateExpression(expression.right!!).toExpectedType(context.builtIns.booleanType)
+        val irArgument0 = statementGenerator.generateExpression(expression.left!!).toExpectedType(context.builtIns.booleanType)
+        val irArgument1 = statementGenerator.generateExpression(expression.right!!).toExpectedType(context.builtIns.booleanType)
         return IrBinaryOperatorExpressionImpl(
                 expression.startOffset, expression.endOffset, context.builtIns.booleanType,
                 irOperator, getResolvedCall(expression)?.resultingDescriptor, irArgument0, irArgument1
@@ -97,7 +99,7 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
     private fun generateInOperator(expression: KtBinaryExpression, irOperator: IrOperator): IrExpression {
         val operatorCall = getResolvedCall(expression)!!
 
-        val irOperatorCall = IrCallGenerator(irStatementGenerator).generateCall(expression, operatorCall, irOperator)
+        val irOperatorCall = CallGenerator(statementGenerator).generateCall(expression, operatorCall, irOperator)
 
         return if (irOperator == IrOperator.IN)
             irOperatorCall
@@ -107,8 +109,8 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
     }
 
     private fun generateIdentityOperator(expression: KtBinaryExpression, irOperator: IrBinaryOperator): IrExpression {
-        val irArgument0 = irStatementGenerator.generateExpression(expression.left!!)
-        val irArgument1 = irStatementGenerator.generateExpression(expression.right!!)
+        val irArgument0 = statementGenerator.generateExpression(expression.left!!)
+        val irArgument1 = statementGenerator.generateExpression(expression.right!!)
         return IrBinaryOperatorExpressionImpl(
                 expression.startOffset, expression.endOffset, context.builtIns.booleanType,
                 irOperator, null, irArgument0, irArgument1
@@ -119,7 +121,7 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
         val relatedCall = getResolvedCall(expression)!!
         val relatedDescriptor = relatedCall.resultingDescriptor
 
-        val irCallGenerator = IrCallGenerator(irStatementGenerator)
+        val irCallGenerator = CallGenerator(statementGenerator)
 
         // NB special typing rules for equality operators: both arguments are nullable
 
@@ -144,7 +146,7 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
         val compareToCall = getResolvedCall(expression)!!
         val compareToDescriptor = compareToCall.resultingDescriptor
 
-        val irCallGenerator = IrCallGenerator(irStatementGenerator)
+        val irCallGenerator = CallGenerator(statementGenerator)
 
         return if (shouldKeepComparisonAsBinaryOperation(compareToDescriptor)) {
             val irArgument0 = irCallGenerator.generateReceiver(expression.left!!, compareToCall.dispatchReceiver, compareToDescriptor.dispatchReceiverParameter!!)!!
@@ -172,7 +174,7 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
 
     private fun generateBinaryOperatorWithConventionalCall(expression: KtBinaryExpression, irOperator: IrOperator?): IrExpression {
         val operatorCall = getResolvedCall(expression)!!
-        return IrCallGenerator(irStatementGenerator).generateCall(expression, operatorCall, irOperator)
+        return CallGenerator(statementGenerator).generateCall(expression, operatorCall, irOperator)
     }
 
     private fun generatePrefixIncrementDecrementOperator(expression: KtPrefixExpression, irOperator: IrOperator): IrExpression {
@@ -184,10 +186,10 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
             return irLValue.prefixAugmentedStore(operatorCall, irOperator)
         }
 
-        val opCallGenerator = IrCallGenerator(irStatementGenerator).apply { putValue(ktBaseExpression, irLValue) }
+        val opCallGenerator = CallGenerator(statementGenerator).apply { putValue(ktBaseExpression, irLValue) }
         val irBlock = IrBlockExpressionImpl(expression.startOffset, expression.endOffset, irLValue.type, true, irOperator)
         val irOpCall = opCallGenerator.generateCall(expression, operatorCall, irOperator)
-        val irTmp = irStatementGenerator.temporaryVariableFactory.createTemporaryVariable(irOpCall)
+        val irTmp = statementGenerator.temporaryVariableFactory.createTemporaryVariable(irOpCall)
         irBlock.addStatement(irTmp)
         irBlock.addStatement(irLValue.store(irTmp.load()))
         irBlock.addStatement(irTmp.load())
@@ -202,10 +204,10 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
         val isSimpleAssignment = get(BindingContext.VARIABLE_REASSIGNMENT, expression) ?: false
 
         if (isSimpleAssignment && irLValue is IrLValueWithAugmentedStore) {
-            return irLValue.augmentedStore(operatorCall, irOperator, irStatementGenerator.generateExpression(expression.right!!))
+            return irLValue.augmentedStore(operatorCall, irOperator, statementGenerator.generateExpression(expression.right!!))
         }
 
-        val opCallGenerator = IrCallGenerator(irStatementGenerator).apply { putValue(ktLeft, irLValue) }
+        val opCallGenerator = CallGenerator(statementGenerator).apply { putValue(ktLeft, irLValue) }
         val irOpCall = opCallGenerator.generateCall(expression, operatorCall, irOperator)
 
         return if (isSimpleAssignment) {
@@ -222,20 +224,20 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
         val ktLeft = expression.left!!
         val ktRight = expression.right!!
         val irLValue = generateLValue(ktLeft, IrOperator.EQ)
-        return irLValue.store(irStatementGenerator.generateExpression(ktRight))
+        return irLValue.store(statementGenerator.generateExpression(ktRight))
     }
 
     private fun generateLValue(ktLeft: KtExpression, irOperator: IrOperator?): IrLValue {
         if (ktLeft is KtArrayAccessExpression) {
-            val irArrayValue = irStatementGenerator.generateExpression(ktLeft.arrayExpression!!)
-            val indexExpressions = ktLeft.indexExpressions.map { it to irStatementGenerator.generateExpression(it) }
+            val irArrayValue = statementGenerator.generateExpression(ktLeft.arrayExpression!!)
+            val indexExpressions = ktLeft.indexExpressions.map { it to statementGenerator.generateExpression(it) }
             val indexedGetCall = get(BindingContext.INDEXED_LVALUE_GET, ktLeft)
             val indexedSetCall = get(BindingContext.INDEXED_LVALUE_SET, ktLeft)
             val type = indexedGetCall?.run { resultingDescriptor.returnType }
                        ?: indexedSetCall?.run { resultingDescriptor.valueParameters.last().type }
                        ?: throw AssertionError("Either 'get' or 'set' call should be present for an indexed LValue: ${ktLeft.text}")
-            return IrIndexedLValue(irStatementGenerator, ktLeft, irOperator,
-                                   irArrayValue, type, indexExpressions, indexedGetCall, indexedSetCall)
+            return IndexedLValue(statementGenerator, ktLeft, irOperator,
+                                 irArrayValue, type, indexExpressions, indexedGetCall, indexedSetCall)
         }
 
         val resolvedCall = getResolvedCall(ktLeft) ?: TODO("no resolved call for LHS")
@@ -246,10 +248,10 @@ class IrOperatorExpressionGenerator(val irStatementGenerator: IrStatementGenerat
                 if (descriptor.isDelegated)
                     TODO("Delegated local variable")
                 else
-                    IrVariableLValue(ktLeft.startOffset, ktLeft.endOffset, descriptor, irOperator)
+                    VariableLValue(ktLeft.startOffset, ktLeft.endOffset, descriptor, irOperator)
             is PropertyDescriptor ->
-                IrCallGenerator(irStatementGenerator).run {
-                    IrPropertyLValue(
+                CallGenerator(statementGenerator).run {
+                    PropertyLValue(
                             ktLeft, irOperator, descriptor,
                             generateReceiver(ktLeft, resolvedCall.dispatchReceiver, descriptor.dispatchReceiverParameter),
                             generateReceiver(ktLeft, resolvedCall.extensionReceiver, descriptor.extensionReceiverParameter),

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

@@ -26,7 +26,7 @@ import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.psi2ir.deparenthesize
-import org.jetbrains.kotlin.psi2ir.generators.values.IrVariableLValue
+import org.jetbrains.kotlin.psi2ir.generators.values.VariableLValue
 import org.jetbrains.kotlin.psi2ir.toExpectedType
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.BindingContextUtils
@@ -38,17 +38,17 @@ import org.jetbrains.kotlin.resolve.constants.evaluate.ConstantExpressionEvaluat
 import org.jetbrains.kotlin.resolve.descriptorUtil.classValueType
 import org.jetbrains.kotlin.types.expressions.ExpressionTypingUtils
 
-class IrStatementGenerator(
-        override val context: IrGeneratorContext,
+class StatementGenerator(
+        override val context: GeneratorContext,
         val scopeOwner: DeclarationDescriptor,
-        val temporaryVariableFactory: IrTemporaryVariableFactory
+        val temporaryVariableFactory: TemporaryVariableFactory
 ) : KtVisitor<IrStatement, Nothing?>(), IrGenerator {
 
     fun generateExpression(ktExpression: KtExpression): IrExpression =
             ktExpression.genExpr()
 
     private fun KtElement.genStmt(): IrStatement =
-            deparenthesize().accept(this@IrStatementGenerator, null)
+            deparenthesize().accept(this@StatementGenerator, null)
 
     private fun KtElement.genExpr(): IrExpression =
             genStmt().assertCast()
@@ -77,8 +77,8 @@ class IrStatementGenerator(
         val irTmpInitializer = temporaryVariableFactory.createTemporaryVariable(ktInitializer.genExpr())
         irBlock.addStatement(irTmpInitializer)
 
-        val irCallGenerator = IrCallGenerator(this)
-        irCallGenerator.putValue(ktInitializer, IrVariableLValue(irTmpInitializer))
+        val irCallGenerator = CallGenerator(this)
+        irCallGenerator.putValue(ktInitializer, VariableLValue(irTmpInitializer))
 
         for ((index, ktEntry) in multiDeclaration.entries.withIndex()) {
             val componentResolvedCall = getOrFail(BindingContext.COMPONENT_RESOLVED_CALL, ktEntry)
@@ -188,7 +188,7 @@ class IrStatementGenerator(
                                                    companionObjectDescriptor)
                 }
             is PropertyDescriptor -> {
-                IrCallGenerator(this).generateCall(expression, resolvedCall)
+                CallGenerator(this).generateCall(expression, resolvedCall)
             }
             is VariableDescriptor ->
                 IrGetVariableExpressionImpl(expression.startOffset, expression.endOffset, descriptor)
@@ -207,7 +207,7 @@ class IrStatementGenerator(
             TODO("VariableAsFunctionResolvedCall = variable call + invoke call")
         }
 
-        return IrCallGenerator(this).generateCall(expression, resolvedCall)
+        return CallGenerator(this).generateCall(expression, resolvedCall)
     }
 
     override fun visitDotQualifiedExpression(expression: KtDotQualifiedExpression, data: Nothing?): IrStatement =
@@ -239,8 +239,38 @@ class IrStatementGenerator(
     }
 
     override fun visitBinaryExpression(expression: KtBinaryExpression, data: Nothing?): IrStatement =
-            IrOperatorExpressionGenerator(this).generateBinaryExpression(expression)
+            OperatorExpressionGenerator(this).generateBinaryExpression(expression)
 
     override fun visitPrefixExpression(expression: KtPrefixExpression, data: Nothing?): IrStatement =
-            IrOperatorExpressionGenerator(this).generatePrefixExpression(expression)
+            OperatorExpressionGenerator(this).generatePrefixExpression(expression)
+
+    override fun visitPostfixExpression(expression: KtPostfixExpression, data: Nothing?): IrStatement =
+            OperatorExpressionGenerator(this).generatePostfixExpression(expression)
+
+    override fun visitIfExpression(expression: KtIfExpression, data: Nothing?): IrStatement {
+        val resultType = getInferredTypeWithSmartcasts(expression)
+        val irWhen = IrWhenExpressionImpl(expression.startOffset, expression.endOffset, resultType)
+
+        var ktBranch: KtIfExpression? = expression
+        branches@while (ktBranch != null) {
+            val irBranch = IrBranchImpl(ktBranch.startOffset, ktBranch.endOffset,
+                                        ktBranch.condition!!.genExpr().toExpectedType(context.builtIns.booleanType),
+                                        ktBranch.then!!.genExpr().toExpectedType(resultType))
+            irWhen.addBranch(irBranch)
+
+            val ktElse = ktBranch.`else`
+
+            ktBranch = when (ktElse) {
+                is KtIfExpression -> ktElse
+                null ->
+                    break@branches
+                else -> {
+                    irWhen.elseExpression = ktElse.genExpr().toExpectedType(resultType)
+                    break@branches
+                }
+            }
+        }
+
+        return irWhen
+    }
 }

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

@@ -26,7 +26,7 @@ import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.KotlinType
 
-class IrTemporaryVariableFactory(val scopeOwner: DeclarationDescriptor) {
+class TemporaryVariableFactory(val scopeOwner: DeclarationDescriptor) {
     private var lastTemporaryIndex = 0
     private fun nextTemporaryIndex() = lastTemporaryIndex++
 

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/values/IndexedLValue.kt

@@ -22,13 +22,13 @@ import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.psi2ir.load
-import org.jetbrains.kotlin.psi2ir.generators.IrCallGenerator
-import org.jetbrains.kotlin.psi2ir.generators.IrStatementGenerator
+import org.jetbrains.kotlin.psi2ir.generators.CallGenerator
+import org.jetbrains.kotlin.psi2ir.generators.StatementGenerator
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
 import org.jetbrains.kotlin.types.KotlinType
 
-class IrIndexedLValue(
-        var irStatementGenerator: IrStatementGenerator,
+class IndexedLValue(
+        var statementGenerator: StatementGenerator,
         val ktArrayAccessExpression: KtArrayAccessExpression,
         val irOperator: IrOperator?,
         val irArray: IrExpression,
@@ -50,7 +50,7 @@ class IrIndexedLValue(
     }
 
     private fun generateGetOrSetCallAsDesugaredBlock(call: ResolvedCall<*>, irArgument: IrExpression? = null): IrExpression {
-        val callGenerator = IrCallGenerator(irStatementGenerator)
+        val callGenerator = CallGenerator(statementGenerator)
         setupCallGeneratorContext(callGenerator)
 
         if (irArgument != null) {
@@ -64,19 +64,19 @@ class IrIndexedLValue(
         if (indexedGetCall == null) throw AssertionError("Indexed LValue has no 'get' call: ${ktArrayAccessExpression.text}")
         if (indexedSetCall == null) throw AssertionError("Indexed LValue has no 'set' call: ${ktArrayAccessExpression.text}")
 
-        val callGenerator = IrCallGenerator(irStatementGenerator)
+        val callGenerator = CallGenerator(statementGenerator)
 
         val irBlock = createDesugaredBlockWithTemporaries(indexedSetCall, callGenerator, true, irOperator)
 
         val operatorCallReceiver = operatorCall.extensionReceiver ?: operatorCall.dispatchReceiver
         callGenerator.putValue(operatorCallReceiver!!,
                                IrSingleExpressionValue(callGenerator.generateCall(ktArrayAccessExpression, indexedGetCall, irOperator)))
-        val irTmp = irStatementGenerator.temporaryVariableFactory.createTemporaryVariable(
+        val irTmp = statementGenerator.temporaryVariableFactory.createTemporaryVariable(
                 callGenerator.generateCall(ktArrayAccessExpression, operatorCall, irOperator))
         irBlock.addStatement(irTmp)
 
         callGenerator.putValue(indexedSetCall.resultingDescriptor.valueParameters.last(),
-                               IrVariableLValue(irTmp))
+                               VariableLValue(irTmp))
 
         irBlock.addStatement(callGenerator.generateCall(ktArrayAccessExpression, indexedSetCall, irOperator))
 
@@ -89,7 +89,7 @@ class IrIndexedLValue(
         if (indexedGetCall == null) throw AssertionError("Indexed LValue has no 'get' call: ${ktArrayAccessExpression.text}")
         if (indexedSetCall == null) throw AssertionError("Indexed LValue has no 'set' call: ${ktArrayAccessExpression.text}")
 
-        val callGenerator = IrCallGenerator(irStatementGenerator)
+        val callGenerator = CallGenerator(statementGenerator)
 
         val irBlock = createDesugaredBlockWithTemporaries(indexedSetCall, callGenerator, false, irOperator)
 
@@ -109,7 +109,7 @@ class IrIndexedLValue(
 
     private fun createDesugaredBlockWithTemporaries(
             call: ResolvedCall<*>,
-            callGenerator: IrCallGenerator,
+            callGenerator: CallGenerator,
             hasResult: Boolean,
             operator: IrOperator?
     ): IrBlockExpressionImpl {
@@ -124,7 +124,7 @@ class IrIndexedLValue(
                                      hasResult, operator)
     }
 
-    private fun defineTemporaryVariables(irBlock: IrBlockExpression, callGenerator: IrCallGenerator) {
+    private fun defineTemporaryVariables(irBlock: IrBlockExpression, callGenerator: CallGenerator) {
         irBlock.addIfNotNull(callGenerator.introduceTemporary(ktArrayAccessExpression.arrayExpression!!, irArray, "array"))
 
         var index = 0
@@ -133,7 +133,7 @@ class IrIndexedLValue(
         }
     }
 
-    private fun setupCallGeneratorContext(callGenerator: IrCallGenerator) {
+    private fun setupCallGeneratorContext(callGenerator: CallGenerator) {
         callGenerator.putValue(ktArrayAccessExpression.arrayExpression!!, IrSingleExpressionValue(irArray))
 
         for ((ktIndexExpression, irIndexValue) in indexValues) {

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/values/PropertyLValue.kt

@@ -24,7 +24,7 @@ import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.psi2ir.toExpectedType
 import org.jetbrains.kotlin.types.KotlinType
 
-class IrPropertyLValue(
+class PropertyLValue(
         val ktElement: KtElement,
         val irOperator: IrOperator?,
         val descriptor: PropertyDescriptor,
@@ -37,8 +37,8 @@ class IrPropertyLValue(
 
     private fun IrPropertyAccessExpression.setReceivers() =
             apply {
-                dispatchReceiver = this@IrPropertyLValue.dispatchReceiver
-                extensionReceiver = this@IrPropertyLValue.extensionReceiver
+                dispatchReceiver = this@PropertyLValue.dispatchReceiver
+                extensionReceiver = this@PropertyLValue.extensionReceiver
             }
 
     override fun load(): IrExpression =

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/values/VariableLValue.kt

@@ -25,7 +25,7 @@ import org.jetbrains.kotlin.ir.expressions.IrSetVariableExpressionImpl
 import org.jetbrains.kotlin.psi2ir.toExpectedType
 import org.jetbrains.kotlin.types.KotlinType
 
-class IrVariableLValue(
+class VariableLValue(
         val startOffset: Int,
         val endOffset: Int,
         val descriptor: VariableDescriptor,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/IrSlots.kt

@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.ir
 
-const val CHILD_DECLARATION_SLOT = 0
 const val DETACHED_SLOT = Int.MIN_VALUE
 const val CHILD_EXPRESSION_SLOT = 0
 const val ARGUMENT0_SLOT = 0
@@ -25,4 +24,8 @@ const val DISPATCH_RECEIVER_SLOT = -1
 const val EXTENSION_RECEIVER_SLOT = -2
 const val FUNCTION_BODY_SLOT = 0
 const val MODULE_SLOT = 0
-const val INITIALIZER_SLOT = 0
+const val INITIALIZER_SLOT = 0
+const val WHEN_SUBJECT_VARIABLE_SLOT = -1
+const val WHEN_ELSE_EXPRESSION_SLOT = -2
+const val BRANCH_CONDITION_SLOT = -1
+const val BRANCH_RESULT_SLOT = -2

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrBlockExpression.kt

@@ -16,10 +16,7 @@
 
 package org.jetbrains.kotlin.ir.expressions
 
-import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.IrStatement
-import org.jetbrains.kotlin.ir.assertCast
-import org.jetbrains.kotlin.ir.assertDetached
+import org.jetbrains.kotlin.ir.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.types.KotlinType
 import java.util.*
@@ -56,8 +53,11 @@ class IrBlockExpressionImpl(
             statements.getOrNull(slot)
 
     override fun replaceChild(slot: Int, newChild: IrElement) {
+        newChild.assertDetached()
         if (0 <= slot && slot < statements.size) {
+            statements[slot].detach()
             statements[slot] = newChild.assertCast()
+            newChild.setTreeLocation(this, slot)
         }
     }
 

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrWhenExpression.kt

@@ -0,0 +1,171 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.ir.expressions
+
+import org.jetbrains.kotlin.ir.*
+import org.jetbrains.kotlin.ir.declarations.IrVariable
+import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
+import org.jetbrains.kotlin.types.KotlinType
+import java.util.*
+
+interface IrWhenExpression : IrExpression {
+    var subject: IrVariable?
+    val branches: List<IrBranch>
+    var elseExpression: IrExpression?
+
+    fun addBranch(branch: IrBranch)
+}
+
+interface IrBranch : IrElement {
+    var condition: IrExpression
+    var result: IrExpression
+}
+
+class IrWhenExpressionImpl(
+        startOffset: Int,
+        endOffset: Int,
+        type: KotlinType?
+) : IrExpressionBase(startOffset, endOffset, type), IrWhenExpression {
+    constructor(
+            startOffset: Int,
+            endOffset: Int,
+            type: KotlinType?,
+            subject: IrVariable
+    ) : this(startOffset, endOffset, type) {
+        this.subject = subject
+    }
+
+    override var subject: IrVariable? = null
+        set(value) {
+            value?.assertDetached()
+            subject?.detach()
+            field = value
+            field?.setTreeLocation(this, WHEN_SUBJECT_VARIABLE_SLOT)
+        }
+
+    override val branches: MutableList<IrBranch> = ArrayList()
+
+    override var elseExpression: IrExpression? = null
+        set(value) {
+            value?.assertDetached()
+            subject?.detach()
+            field = value
+            field?.setTreeLocation(this, WHEN_ELSE_EXPRESSION_SLOT)
+        }
+
+    override fun addBranch(branch: IrBranch) {
+        branch.assertDetached()
+        branch.setTreeLocation(this, branches.size)
+        branches.add(branch)
+    }
+
+    override fun getChild(slot: Int): IrElement? =
+            when (slot) {
+                WHEN_SUBJECT_VARIABLE_SLOT -> subject
+                WHEN_ELSE_EXPRESSION_SLOT -> elseExpression
+                else -> branches.getOrNull(slot)
+            }
+
+    override fun replaceChild(slot: Int, newChild: IrElement) {
+        newChild.assertDetached()
+        when (slot) {
+            WHEN_SUBJECT_VARIABLE_SLOT ->
+                subject = newChild.assertCast()
+            WHEN_ELSE_EXPRESSION_SLOT ->
+                elseExpression = newChild.assertCast()
+            in branches.indices -> {
+                branches[slot].detach()
+                branches[slot] = newChild.assertCast()
+                newChild.setTreeLocation(this, slot)
+            }
+        }
+    }
+
+    override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =
+            visitor.visitWhenExpression(this, data)
+
+    override fun <D> acceptChildren(visitor: IrElementVisitor<Unit, D>, data: D) {
+        subject?.accept(visitor, data)
+        branches.forEach { it.accept(visitor, data) }
+        elseExpression?.accept(visitor, data)
+    }
+
+    companion object {
+        fun ifThen(startOffset: Int, endOffset: Int, type: KotlinType?, condition: IrExpression, thenExpression: IrExpression) =
+                IrWhenExpressionImpl(startOffset, endOffset, type).apply {
+                    addBranch(IrBranchImpl(startOffset, endOffset, condition, thenExpression))
+                }
+
+        fun ifThenElse(startOffset: Int, endOffset: Int, type: KotlinType?,
+                       condition: IrExpression, thenExpression: IrExpression, elseExpression: IrExpression) =
+                IrWhenExpressionImpl(startOffset, endOffset, type).apply {
+                    addBranch(IrBranchImpl(startOffset, endOffset, condition, thenExpression))
+                    this.elseExpression = elseExpression
+                }
+    }
+}
+
+class IrBranchImpl(startOffset: Int, endOffset: Int) : IrElementBase(startOffset, endOffset), IrBranch {
+    constructor(startOffset: Int, endOffset: Int, condition: IrExpression, result: IrExpression) : this(startOffset, endOffset) {
+        this.condition = condition
+        this.result = result
+    }
+
+    private var conditionImpl: IrExpression? = null
+    override var condition: IrExpression
+        get() = conditionImpl!!
+        set(value) {
+            value.assertDetached()
+            conditionImpl?.detach()
+            conditionImpl = value
+            value.setTreeLocation(this, BRANCH_CONDITION_SLOT)
+        }
+
+    private var resultImpl: IrExpression? = null
+    override var result: IrExpression
+        get() = resultImpl!!
+        set(value) {
+            value.assertDetached()
+            resultImpl?.detach()
+            resultImpl = value
+            value.setTreeLocation(this, BRANCH_RESULT_SLOT)
+        }
+
+    override fun getChild(slot: Int): IrElement? =
+            when (slot) {
+                BRANCH_CONDITION_SLOT -> condition
+                BRANCH_RESULT_SLOT -> result
+                else -> null
+            }
+
+    override fun replaceChild(slot: Int, newChild: IrElement) {
+        when (slot) {
+            BRANCH_CONDITION_SLOT ->
+                condition = newChild.assertCast()
+            BRANCH_RESULT_SLOT ->
+                result = newChild.assertCast()
+        }
+    }
+
+    override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =
+            visitor.visitBranch(this, data)
+
+    override fun <D> acceptChildren(visitor: IrElementVisitor<Unit, D>, data: D) {
+        conditionImpl?.accept(visitor, data)
+        resultImpl?.accept(visitor, data)
+    }
+}

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DumpIrTree.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.expressions.IrCallExpression
 import org.jetbrains.kotlin.ir.expressions.IrGetPropertyExpression
 import org.jetbrains.kotlin.ir.expressions.IrSetPropertyExpression
+import org.jetbrains.kotlin.ir.expressions.IrWhenExpression
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.utils.Printer
 
@@ -70,6 +71,19 @@ class DumpIrTreeVisitor(out: Appendable): IrElementVisitor<Unit, String> {
         }
     }
 
+    override fun visitWhenExpression(expression: IrWhenExpression, data: String) {
+        expression.dumpLabeledElementWith(data) {
+            expression.subject?.let { subject ->
+                subject.accept(this, "\$subject:")
+            }
+            for (branch in expression.branches) {
+                branch.condition.accept(this, "if")
+                branch.result.accept(this, "then")
+            }
+            expression.elseExpression?.accept(this, "else")
+        }
+    }
+
     private inline fun IrElement.dumpLabeledElementWith(label: String, body: () -> Unit) {
         printer.println(accept(elementRenderer, null).withLabel(label))
         indented(body)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt

@@ -112,9 +112,14 @@ class RenderIrElementVisitor : IrElementVisitor<String, Nothing?> {
     override fun visitStringConcatenation(expression: IrStringConcatenationExpression, data: Nothing?): String =
             "STRING_CONCATENATION type=${expression.renderType()}"
 
-    override fun visitTypeOperatorExpression(expression: IrTypeOperatorExpression, data: Nothing?): String {
-        return "TYPE_OP operator=${expression.operator} typeOperand=${expression.typeOperand.render()}"
-    }
+    override fun visitTypeOperatorExpression(expression: IrTypeOperatorExpression, data: Nothing?): String =
+            "TYPE_OP operator=${expression.operator} typeOperand=${expression.typeOperand.render()}"
+
+    override fun visitWhenExpression(expression: IrWhenExpression, data: Nothing?): String =
+            "WHEN subject=${expression.subject?.descriptor?.name} type=${expression.type.render()}"
+
+    override fun visitBranch(branch: IrBranch, data: Nothing?): String =
+            "BRANCH"
 
     override fun visitDummyDeclaration(declaration: IrDummyDeclaration, data: Nothing?): String =
             "DUMMY ${declaration.descriptor.name}"

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/visitors/IrElementVisitor.kt

@@ -63,8 +63,10 @@ interface IrElementVisitor<out R, in D> {
     fun visitBinaryOperator(expression: IrBinaryOperatorExpression, data: D) = visitOperatorExpression(expression, data)
     fun visitTypeOperatorExpression(expression: IrTypeOperatorExpression, data: D) = visitExpression(expression, data)
 
+    fun visitWhenExpression(expression: IrWhenExpression, data: D) = visitExpression(expression, data)
+    fun visitBranch(branch: IrBranch, data: D): R = visitElement(branch, data)
+
     // NB Use it only for testing purposes; will be removed as soon as all Kotlin expression types are covered
     fun visitDummyDeclaration(declaration: IrDummyDeclaration, data: D) = visitDeclaration(declaration, data)
     fun visitDummyExpression(expression: IrDummyExpression, data: D) = visitExpression(expression, data)
-
 }

compiler/testData/ir/irText/elvis.txt

@@ -16,8 +16,14 @@ IrFile /elvis.kt
   IrFunction public fun test3(/*0*/ a: kotlin.Any?, /*1*/ b: kotlin.Any?): kotlin.String
     IrExpressionBody
       BLOCK type=<no-type> hasResult=false operator=null
-        DUMMY KtIfExpression type=kotlin.Unit
-        DUMMY KtIfExpression type=kotlin.Unit
+        WHEN subject=null type=kotlin.Unit
+          if: DUMMY KtIsExpression type=kotlin.Boolean
+          then: RETURN type=<no-type>
+            LITERAL String type=kotlin.String value=''
+        WHEN subject=null type=kotlin.Unit
+          if: DUMMY KtIsExpression type=kotlin.Boolean
+          then: RETURN type=<no-type>
+            LITERAL String type=kotlin.String value=''
         RETURN type=<no-type>
           BINARY_OP operator=ELVIS type=kotlin.String related=null
             TYPE_OP operator=IMPLICIT_CAST typeOperand=kotlin.String?

compiler/testData/ir/irText/ifElseIf.kt

@@ -0,0 +1,4 @@
+fun test(i: Int) =
+        if (i > 0) 1
+        else if (i < 0) -1
+        else 0

compiler/testData/ir/irText/ifElseIf.txt

@@ -0,0 +1,15 @@
+IrFile /ifElseIf.kt
+  IrFunction public fun test(/*0*/ i: kotlin.Int): kotlin.Int
+    IrExpressionBody
+      BLOCK type=<no-type> hasResult=false operator=null
+        RETURN type=<no-type>
+          WHEN subject=null type=kotlin.Int
+            if: BINARY_OP operator=GT type=kotlin.Boolean related=public open override /*1*/ fun compareTo(/*0*/ other: kotlin.Int): kotlin.Int
+              GET_VAR i type=kotlin.Int operator=null
+              LITERAL Int type=kotlin.Int value='0'
+            then: LITERAL Int type=kotlin.Int value='1'
+            if: BINARY_OP operator=LT type=kotlin.Boolean related=public open override /*1*/ fun compareTo(/*0*/ other: kotlin.Int): kotlin.Int
+              GET_VAR i type=kotlin.Int operator=null
+              LITERAL Int type=kotlin.Int value='0'
+            then: DUMMY MINUS type=kotlin.Int
+            else: LITERAL Int type=kotlin.Int value='0'

compiler/testData/ir/irText/smartCasts.txt

@@ -18,7 +18,9 @@ IrFile /smartCasts.kt
   IrFunction public fun test1(/*0*/ x: kotlin.Any): kotlin.Unit
     IrExpressionBody
       BLOCK type=<no-type> hasResult=false operator=null
-        DUMMY KtIfExpression type=kotlin.Unit
+        WHEN subject=null type=kotlin.Unit
+          if: DUMMY KtIsExpression type=kotlin.Boolean
+          then: RETURN type=<no-type>
         CALL .println type=kotlin.Unit operator=null
           message: GET_PROPERTY .length type=kotlin.Int operator=null
             $this: TYPE_OP operator=IMPLICIT_CAST typeOperand=kotlin.String
@@ -37,7 +39,10 @@ IrFile /smartCasts.kt
   IrFunction public fun test2(/*0*/ x: kotlin.Any): kotlin.String
     IrExpressionBody
       BLOCK type=<no-type> hasResult=false operator=null
-        DUMMY KtIfExpression type=kotlin.Unit
+        WHEN subject=null type=kotlin.Unit
+          if: DUMMY KtIsExpression type=kotlin.Boolean
+          then: RETURN type=<no-type>
+            LITERAL String type=kotlin.String value=''
         RETURN type=<no-type>
           CALL .overloaded type=kotlin.String operator=null
             s: TYPE_OP operator=IMPLICIT_CAST typeOperand=kotlin.String
@@ -45,7 +50,10 @@ IrFile /smartCasts.kt
   IrFunction public fun test3(/*0*/ x: kotlin.Any): kotlin.String
     IrExpressionBody
       BLOCK type=<no-type> hasResult=false operator=null
-        DUMMY KtIfExpression type=kotlin.Unit
+        WHEN subject=null type=kotlin.Unit
+          if: DUMMY KtIsExpression type=kotlin.Boolean
+          then: RETURN type=<no-type>
+            LITERAL String type=kotlin.String value=''
         RETURN type=<no-type>
           TYPE_OP operator=IMPLICIT_CAST typeOperand=kotlin.String
             GET_VAR x type=kotlin.Any operator=null

compiler/testData/ir/irText/smartCastsWithDestructuring.txt

@@ -14,7 +14,9 @@ IrFile /smartCastsWithDestructuring.kt
   IrFunction public fun test(/*0*/ x: I1): kotlin.Unit
     IrExpressionBody
       BLOCK type=<no-type> hasResult=false operator=null
-        DUMMY KtIfExpression type=kotlin.Unit
+        WHEN subject=null type=kotlin.Unit
+          if: DUMMY KtIsExpression type=kotlin.Boolean
+          then: RETURN type=<no-type>
         BLOCK type=<no-type> hasResult=false operator=SYNTHETIC_BLOCK
           VAR val tmp0: I1
             GET_VAR x type=I1 operator=null

compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java

@@ -137,6 +137,12 @@ public class IrTextTestCaseGenerated extends AbstractIrTextTestCase {
         doTest(fileName);
     }
 
+    @TestMetadata("ifElseIf.kt")
+    public void testIfElseIf() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/ifElseIf.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("implicitCastOnPlatformType.kt")
     public void testImplicitCastOnPlatformType() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/implicitCastOnPlatformType.kt");