IR: remove cast to IrStatement in IrDeclarationBase.transform

Default implementation of `IrStatement.transform` contained a cast to
`IrStatement`. Since almost all IR elements inherit from IrStatement,
this implementation was used in many subclasses. However, checkcast to
interface is slow and this place was indeed noticeable in the profiler
snapshot. Since not that many places really expected to get IrStatement
out of IrStatement.transform, introduce a new method
`transformStatement` that does this cast, and use it in all those
places. Meanwhile, most implementations will use the IrElement's
implementation of `transform` which merely invokes `accept` without
casts.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/InlineClassDeclarationLowering.kt

@@ -15,6 +15,7 @@ import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.transformStatement
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
@@ -83,7 +84,7 @@ class InlineClassLowering(val context: CommonBackendContext) {
                     }
 
                     (irConstructor.body as IrBlockBody).statements.forEach { statement ->
-                        +statement.transform(object : IrElementTransformerVoid() {
+                        +statement.transformStatement(object : IrElementTransformerVoid() {
                             override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall): IrExpression {
                                 expression.transformChildrenVoid()
                                 return irBlock(expression) {
@@ -124,7 +125,7 @@ class InlineClassLowering(val context: CommonBackendContext) {
                                 return expression
                             }
 
-                        }, null)
+                        })
                     }
                     +irReturn(irGet(thisVar))
                 }.statements

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LocalDeclarationsLowering.kt

@@ -12,10 +12,7 @@ import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.ReceiverParameterDescriptor
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
-import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.*
-import org.jetbrains.kotlin.ir.IrStatement
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
-import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.builders.Scope
 import org.jetbrains.kotlin.ir.builders.declarations.buildConstructor
 import org.jetbrains.kotlin.ir.builders.declarations.buildField
@@ -267,9 +264,9 @@ class LocalDeclarationsLowering(
 
 
         private inner class FunctionBodiesRewriter(val localContext: LocalContext?) : IrElementTransformerVoid() {
-            override fun visitLocalDelegatedProperty(declaration: IrLocalDelegatedProperty) =
+            override fun visitLocalDelegatedProperty(declaration: IrLocalDelegatedProperty): IrStatement =
                 // Both accessors extracted as closures.
-                declaration.delegate.transform(this, null)
+                declaration.delegate.transformStatement(this)
 
             override fun visitClass(declaration: IrClass) = if (declaration in localClasses) {
                 localClasses[declaration]!!.declaration

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/ReturnableBlockLowering.kt

@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrDoWhileLoopImpl
 import org.jetbrains.kotlin.ir.symbols.IrReturnableBlockSymbol
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
+import org.jetbrains.kotlin.ir.transformStatement
 
 /**
  * Replaces returnable blocks and `return`'s with loops and `break`'s correspondingly.
@@ -118,7 +119,7 @@ class ReturnableBlockTransformer(val context: CommonBackendContext, val containe
                     builder.irSetVar(variable.symbol, s.value)
                 }
             } else {
-                s.transform(this, null)
+                s.transformStatement(this)
             }
         }
 

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/TailrecLowering.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetValueImpl
 import org.jetbrains.kotlin.ir.symbols.IrValueParameterSymbol
+import org.jetbrains.kotlin.ir.transformStatement
 import org.jetbrains.kotlin.ir.util.explicitParameters
 import org.jetbrains.kotlin.ir.util.getArgumentsWithIr
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
@@ -100,7 +101,7 @@ private fun lowerTailRecursionCalls(context: BackendContext, irFunction: IrFunct
                 )
 
                 oldBodyStatements.forEach {
-                    +it.transform(transformer, null)
+                    +it.transformStatement(transformer)
                 }
 
                 +irBreak(loop)

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BlockDecomposerLowering.kt

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.ir.builders.declarations.buildFun
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
+import org.jetbrains.kotlin.ir.transformStatement
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.util.dump
 import org.jetbrains.kotlin.ir.util.patchDeclarationParents
@@ -123,7 +124,7 @@ class BlockDecomposerTransformer(
             val transformedStatements = mutableListOf<IrStatement>()
             statements.forEach {
                 val transformer = if (it === statements.last()) expressionTransformer else statementTransformer
-                val s = it.transform(transformer, null)
+                val s = it.transformStatement(transformer)
                 if (s is IrComposite) {
                     transformedStatements.addAll(s.statements)
                 } else {
@@ -139,14 +140,14 @@ class BlockDecomposerTransformer(
     override fun visitFunction(declaration: IrFunction): IrStatement {
         function = declaration
         tmpVarCounter = 0
-        return declaration.transform(statementTransformer, null)
+        return declaration.transformStatement(statementTransformer)
     }
 
     override fun visitElement(element: IrElement) = element.transform(statementTransformer, null)
 
     private fun processStatements(statements: MutableList<IrStatement>) {
         statements.transformFlat {
-            destructureComposite(it.transform(statementTransformer, null))
+            destructureComposite(it.transformStatement(statementTransformer))
         }
     }
 
@@ -157,7 +158,7 @@ class BlockDecomposerTransformer(
 
     private fun IrStatement.asExpression(last: IrExpression): IrExpression {
         val composite = JsIrBuilder.buildComposite(last.type)
-        composite.statements += transform(statementTransformer, null)
+        composite.statements += transformStatement(statementTransformer)
         composite.statements += last
         return composite
     }
@@ -658,10 +659,10 @@ class BlockDecomposerTransformer(
             val newStatements = mutableListOf<IrStatement>()
 
             for (i in 0 until expression.statements.lastIndex) {
-                newStatements += destructureComposite(expression.statements[i].transform(statementTransformer, null))
+                newStatements += destructureComposite(expression.statements[i].transformStatement(statementTransformer))
             }
 
-            newStatements += destructureComposite(expression.statements.last().transform(expressionTransformer, null))
+            newStatements += destructureComposite(expression.statements.last().transformStatement(expressionTransformer))
 
             return JsIrBuilder.buildComposite(expression.type, newStatements)
         }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.ir.expressions.impl.IrGetValueImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrSetVariableImpl
 import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
 import org.jetbrains.kotlin.ir.symbols.IrVariableSymbol
+import org.jetbrains.kotlin.ir.transformStatement
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classOrNull
 import org.jetbrains.kotlin.ir.types.isNullable
@@ -202,7 +203,7 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
 
             constructor.body?.statements?.forEach { statement ->
                 +statement
-                    .transform(object : IrElementTransformerVoid() {
+                    .transformStatement(object : IrElementTransformerVoid() {
                         // Don't recurse under nested class declarations
                         override fun visitClass(declaration: IrClass): IrStatement {
                             return declaration
@@ -239,8 +240,8 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
                                 +irGet(thisVar)
                             })
                         }
-                    }, null)
+                    })
-                    .transform(this@JvmInlineClassLowering, null)
+                    .transformStatement(this@JvmInlineClassLowering)
                     .patchDeclarationParents(replacement)
             }
 
@@ -427,7 +428,7 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
             if (statement is IrFunction)
                 transformFunctionFlat(statement)
             else
-                listOf(statement.transform(this, null))
+                listOf(statement.transformStatement(this))
         }
     }
 

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

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.ir
 
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 
 interface IrElement {
@@ -33,10 +34,10 @@ interface IrElement {
     fun <D> transformChildren(transformer: IrElementTransformer<D>, data: D): Unit
 }
 
-interface IrStatement : IrElement {
+interface IrStatement : IrElement
-    override fun <D> transform(transformer: IrElementTransformer<D>, data: D): IrStatement =
+
-        super.transform(transformer, data) as IrStatement
+fun IrStatement.transformStatement(transformer: IrElementTransformerVoid): IrStatement =
-}
+    transform(transformer, null) as IrStatement
 
 inline fun <reified T : IrElement> IrElement.assertCast(): T =
     if (this is T) this else throw AssertionError("Expected ${T::class.simpleName}: $this")

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrDeclaration.kt

@@ -24,7 +24,6 @@ import org.jetbrains.kotlin.ir.IrElementBase
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
-import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 import org.jetbrains.kotlin.name.Name
 
 interface IrSymbolOwner : IrElement {
@@ -46,10 +45,7 @@ interface IrDeclaration : IrStatement, IrMutableAnnotationContainer {
     val factory: IrFactory
 }
 
-abstract class IrDeclarationBase : IrElementBase(), IrDeclaration {
+abstract class IrDeclarationBase : IrElementBase(), IrDeclaration
-    override fun <D> transform(transformer: IrElementTransformer<D>, data: D): IrStatement =
-        accept(transformer, data) as IrStatement
-}
 
 interface IrSymbolDeclaration<out S : IrSymbol> : IrDeclaration, IrSymbolOwner {
     override val symbol: S

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

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.ir.expressions
 
 import org.jetbrains.kotlin.ir.IrElementBase
+import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.declarations.IrFactory
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
@@ -58,7 +59,7 @@ abstract class IrBlockBody : IrBody(), IrStatementContainer {
 
     override fun <D> transformChildren(transformer: IrElementTransformer<D>, data: D) {
         statements.forEachIndexed { i, irStatement ->
-            statements[i] = irStatement.transform(transformer, data)
+            statements[i] = irStatement.transform(transformer, data) as IrStatement
         }
     }
 }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockImpl.kt

@@ -97,7 +97,7 @@ class IrReturnableBlockImpl(
 
     override fun <D> transformChildren(transformer: IrElementTransformer<D>, data: D) {
         statements.forEachIndexed { i, irStatement ->
-            statements[i] = irStatement.transform(transformer, data)
+            statements[i] = irStatement.transform(transformer, data) as IrStatement
         }
     }
 }