[JS IR] Namer improvements

- Compute and store local names locally when translating a body.
  It is a step towards separate JS generation and hopefully reduces memory usage.

- Use stable mangled names for member names. Needed for separate JS generation.

- Add `abstract class IrNamerBase` with just 3 abstract methods to simplify
  creating new IrNamer implementations.

- Fix O(N^2) of findFreshName when it is called wtih the same name suggestion a lot of times.

- Refactor NameTables initialisation: factor out some functions and use descriptive names.

- Use StringBuilder in sanitizeName

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

@@ -7,14 +7,13 @@ package org.jetbrains.kotlin.ir.backend.js.lower
 
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
-import org.jetbrains.kotlin.ir.backend.js.utils.Signature
 import org.jetbrains.kotlin.ir.backend.js.utils.hasStableJsName
 import org.jetbrains.kotlin.ir.backend.js.utils.jsFunctionSignature
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 
 class JsBridgesConstruction(context: JsIrBackendContext) : BridgesConstruction<JsIrBackendContext>(context) {
-    override fun getFunctionSignature(function: IrSimpleFunction): Signature =
+    override fun getFunctionSignature(function: IrSimpleFunction): String =
         jsFunctionSignature(function, context)
 
     override fun getBridgeOrigin(bridge: IrSimpleFunction): IrDeclarationOrigin =

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrFunctionToJsTransformer.kt

@@ -6,8 +6,8 @@
 package org.jetbrains.kotlin.ir.backend.js.transformers.irToJs
 
 import org.jetbrains.kotlin.ir.backend.js.utils.JsGenerationContext
-import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrConstructor
+import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.js.backend.ast.JsFunction
 
@@ -15,7 +15,11 @@ import org.jetbrains.kotlin.js.backend.ast.JsFunction
 class IrFunctionToJsTransformer : BaseIrElementToJsNodeTransformer<JsFunction, JsGenerationContext> {
     override fun visitSimpleFunction(declaration: IrSimpleFunction, context: JsGenerationContext): JsFunction {
         val funcName = if (declaration.dispatchReceiverParameter == null) {
-            context.getNameForStaticFunction(declaration)
+            if (declaration.parent is IrFunction) {
+                context.getNameForValueDeclaration(declaration)
+            } else {
+                context.getNameForStaticFunction(declaration)
+            }
         } else {
             context.getNameForMemberFunction(declaration)
         }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrModuleToJsTransformer.kt

@@ -127,16 +127,18 @@ class IrModuleToJsTransformer(
     ): String {
 
         val nameGenerator = refInfo.withReferenceTracking(
-            IrNamerImpl(newNameTables = namer),
+            IrNamerImpl(newNameTables = namer, backendContext),
             modules
         )
         val staticContext = JsStaticContext(
             backendContext = backendContext,
-            irNamer = nameGenerator
+            irNamer = nameGenerator,
+            globalNameScope = namer.globalNames
         )
         val rootContext = JsGenerationContext(
             currentFunction = null,
-            staticContext = staticContext
+            staticContext = staticContext,
+            localNames = LocalNameGenerator(NameScope.EmptyScope)
         )
 
         val (importStatements, importedJsModules) =

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt

@@ -5,12 +5,10 @@
 
 package org.jetbrains.kotlin.ir.backend.js.transformers.irToJs
 
-import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.backend.js.utils.*
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.IrClassReference
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
 import org.jetbrains.kotlin.ir.types.IrType
@@ -26,8 +24,11 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
     private val className = context.getNameForClass(irClass)
     private val classNameRef = className.makeRef()
     private val baseClass: IrType? = irClass.superTypes.firstOrNull { !it.classifierOrFail.isInterface }
-    private val baseClassName = baseClass?.let {
-        context.getNameForClass(baseClass.classifierOrFail.owner as IrClass)
+
+    private val baseClassName by lazy { // Lazy in case was not collected by namer during JsClassGenerator construction
+        baseClass?.let {
+            context.getNameForClass(baseClass.classifierOrFail.owner as IrClass)
+        }
     }
     private val classPrototypeRef = prototypeOf(classNameRef)
     private val classBlock = JsGlobalBlock()

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/jsAstUtils.kt

@@ -14,6 +14,8 @@ import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
 import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
+import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.util.OperatorNameConventions
 
@@ -50,7 +52,14 @@ fun translateFunction(declaration: IrFunction, name: JsName?, context: JsGenerat
         return function
     }
 
-    val functionContext = context.newDeclaration(declaration)
+    val localNameGenerator = context.localNames
+        ?: LocalNameGenerator(context.staticContext.globalNameScope).also {
+            declaration.acceptChildrenVoid(it)
+            declaration.parentClassOrNull?.thisReceiver?.acceptVoid(it)
+        }
+
+    val functionContext = context.newDeclaration(declaration, localNameGenerator)
+
     val functionParams = declaration.valueParameters.map { functionContext.getNameForValueDeclaration(it) }
     val body = declaration.body?.accept(IrElementToJsStatementTransformer(), functionContext) as? JsBlock ?: JsBlock()
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrNamer.kt

@@ -6,21 +6,81 @@
 package org.jetbrains.kotlin.ir.backend.js.utils
 
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.IrLoop
+import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.js.backend.ast.JsName
 import org.jetbrains.kotlin.js.backend.ast.JsNameRef
 
 interface IrNamer {
-    fun getNameForConstructor(constructor: IrConstructor): JsName
     fun getNameForMemberFunction(function: IrSimpleFunction): JsName
     fun getNameForMemberField(field: IrField): JsName
-    fun getNameForField(field: IrField): JsName
-    fun getNameForValueDeclaration(declaration: IrValueDeclaration): JsName
-    fun getNameForClass(klass: IrClass): JsName
-    fun getNameForStaticFunction(function: IrSimpleFunction): JsName
     fun getNameForStaticDeclaration(declaration: IrDeclarationWithName): JsName
-    fun getNameForProperty(property: IrProperty): JsName
+    fun getNameForStaticFunction(function: IrSimpleFunction): JsName
+    fun getNameForField(field: IrField): JsName
+    fun getNameForConstructor(constructor: IrConstructor): JsName
+    fun getNameForClass(klass: IrClass): JsName
     fun getRefForExternalClass(klass: IrClass): JsNameRef
-    fun getNameForLoop(loop: IrLoop): JsName?
+    fun getNameForProperty(property: IrProperty): JsName
     fun getAssociatedObjectKey(irClass: IrClass): Int?
+}
+
+abstract class IrNamerBase : IrNamer {
+    abstract override fun getNameForMemberFunction(function: IrSimpleFunction): JsName
+    abstract override fun getNameForMemberField(field: IrField): JsName
+    abstract override fun getNameForStaticDeclaration(declaration: IrDeclarationWithName): JsName
+
+    protected fun String.toJsName() = JsName(this)
+
+    override fun getNameForStaticFunction(function: IrSimpleFunction): JsName =
+        getNameForStaticDeclaration(function)
+
+    override fun getNameForField(field: IrField): JsName {
+        return if (field.isStatic || field.parent is IrScript) {
+            getNameForStaticDeclaration(field)
+        } else {
+            getNameForMemberField(field)
+        }
+    }
+
+    override fun getNameForConstructor(constructor: IrConstructor): JsName =
+        getNameForStaticDeclaration(constructor.parentAsClass)
+
+    override fun getNameForClass(klass: IrClass): JsName =
+        getNameForStaticDeclaration(klass)
+
+    override fun getRefForExternalClass(klass: IrClass): JsNameRef {
+        val parent = klass.parent
+        if (klass.isCompanion)
+            return getRefForExternalClass(parent as IrClass)
+
+        val currentClassName = klass.getJsNameOrKotlinName().identifier
+        return when (parent) {
+            is IrClass ->
+                JsNameRef(currentClassName, getRefForExternalClass(parent))
+
+            is IrPackageFragment -> {
+                getNameForStaticDeclaration(klass).makeRef()
+            }
+
+            else ->
+                error("Unsupported external class parent $parent")
+        }
+    }
+
+    override fun getNameForProperty(property: IrProperty): JsName {
+        return if (property.parent is IrClass) {
+            property.getJsNameOrKotlinName().asString().toJsName()
+        } else {
+            getNameForStaticDeclaration(property)
+        }
+    }
+
+    private val associatedObjectKeyMap = mutableMapOf<IrClass, Int>()
+
+    override fun getAssociatedObjectKey(irClass: IrClass): Int? {
+        if (irClass.isAssociatedObjectAnnotatedAnnotation) {
+
+            return associatedObjectKeyMap.getOrPut(irClass) { associatedObjectKeyMap.size }
+        }
+        return null
+    }
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrNamerImpl.kt

@@ -5,82 +5,27 @@
 
 package org.jetbrains.kotlin.ir.backend.js.utils
 
-import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.IrLoop
-import org.jetbrains.kotlin.ir.util.parentAsClass
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationWithName
+import org.jetbrains.kotlin.ir.declarations.IrField
+import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.js.backend.ast.JsName
-import org.jetbrains.kotlin.js.backend.ast.JsNameRef
-import org.jetbrains.kotlin.js.backend.ast.JsRootScope
-
-class IrNamerImpl(private val newNameTables: NameTables) : IrNamer {
-
-    private fun String.toJsName() = JsName(this)
 
+class IrNamerImpl(
+    private val newNameTables: NameTables,
+    private val context: JsIrBackendContext,
+) : IrNamerBase() {
     override fun getNameForStaticDeclaration(declaration: IrDeclarationWithName): JsName =
         newNameTables.getNameForStaticDeclaration(declaration).toJsName()
 
-    override fun getNameForLoop(loop: IrLoop): JsName? =
-        newNameTables.getNameForLoop(loop)?.toJsName()
-
-    override fun getNameForConstructor(constructor: IrConstructor): JsName {
-        return getNameForStaticDeclaration(constructor.parentAsClass)
-    }
-
     override fun getNameForMemberFunction(function: IrSimpleFunction): JsName {
         require(function.dispatchReceiverParameter != null)
-        return newNameTables.getNameForMemberFunction(function).toJsName()
+        val signature = jsFunctionSignature(function, context)
+        return signature.toJsName()
     }
 
     override fun getNameForMemberField(field: IrField): JsName {
         require(!field.isStatic)
         return newNameTables.getNameForMemberField(field).toJsName()
     }
-
-    override fun getNameForField(field: IrField): JsName {
-        return if (field.isStatic || field.parent is IrScript) {
-            getNameForStaticDeclaration(field)
-        } else {
-            getNameForMemberField(field)
-        }
-    }
-
-    override fun getNameForValueDeclaration(declaration: IrValueDeclaration): JsName =
-        getNameForStaticDeclaration(declaration)
-
-    override fun getNameForClass(klass: IrClass): JsName =
-        getNameForStaticDeclaration(klass)
-
-    override fun getNameForStaticFunction(function: IrSimpleFunction): JsName =
-        getNameForStaticDeclaration(function)
-
-    override fun getNameForProperty(property: IrProperty): JsName =
-        property.getJsNameOrKotlinName().asString().toJsName()
-
-    override fun getRefForExternalClass(klass: IrClass): JsNameRef {
-        val parent = klass.parent
-        if (klass.isCompanion)
-            return getRefForExternalClass(parent as IrClass)
-
-        val currentClassName = klass.getJsNameOrKotlinName().identifier
-        return when (parent) {
-            is IrClass ->
-                JsNameRef(currentClassName, getRefForExternalClass(parent))
-
-            is IrPackageFragment ->
-                JsNameRef(currentClassName)
-
-            else ->
-                error("Unsupported external class parent $parent")
-        }
-    }
-
-    private val associatedObjectKeyMap = mutableMapOf<IrClass, Int>()
-
-    override fun getAssociatedObjectKey(irClass: IrClass): Int? {
-        if (irClass.isAssociatedObjectAnnotatedAnnotation) {
-
-            return associatedObjectKeyMap.getOrPut(irClass) { associatedObjectKeyMap.size }
-        }
-        return null
-    }
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/JsGenerationContext.kt

@@ -5,8 +5,10 @@
 
 package org.jetbrains.kotlin.ir.backend.js.utils
 
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationWithName
 import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
+import org.jetbrains.kotlin.ir.expressions.IrLoop
 import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
 import org.jetbrains.kotlin.ir.util.isSuspend
 import org.jetbrains.kotlin.js.backend.ast.JsName
@@ -23,12 +25,14 @@ val emptyScope: JsScope
 
 class JsGenerationContext(
     val currentFunction: IrFunction?,
-    val staticContext: JsStaticContext
+    val staticContext: JsStaticContext,
+    val localNames: LocalNameGenerator? = null
 ): IrNamer by staticContext {
-    fun newDeclaration(func: IrFunction? = null): JsGenerationContext {
+    fun newDeclaration(func: IrFunction? = null, localNames: LocalNameGenerator? = null): JsGenerationContext {
         return JsGenerationContext(
             currentFunction = func,
-            staticContext = staticContext
+            staticContext = staticContext,
+            localNames = localNames,
         )
     }
 
@@ -39,10 +43,21 @@ class JsGenerationContext(
             if (currentFunction!!.isSuspend) {
                 JsNameRef(Namer.CONTINUATION)
             } else {
-                getNameForValueDeclaration(currentFunction.valueParameters.last()).makeRef()
+                JsNameRef(this.getNameForValueDeclaration(currentFunction.valueParameters.last()))
             }
         }
 
+    fun getNameForValueDeclaration(declaration: IrDeclarationWithName): JsName {
+        val name = localNames!!.variableNames.names[declaration]
+            ?: error("Variable name is not found ${declaration.name}")
+        return JsName(name)
+    }
+
+    fun getNameForLoop(loop: IrLoop): JsName? {
+        val name = localNames!!.localLoopNames.names[loop] ?: return null
+        return JsName(name)
+    }
+
     private fun isCoroutineDoResume(): Boolean {
         val overriddenSymbols = (currentFunction as? IrSimpleFunction)?.overriddenSymbols ?: return false
         return overriddenSymbols.any {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/JsStaticContext.kt

@@ -8,16 +8,15 @@ package org.jetbrains.kotlin.ir.backend.js.utils
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.JsIntrinsicTransformers
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.JsIrClassModel
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.js.backend.ast.JsGlobalBlock
 
 
 class JsStaticContext(
     val backendContext: JsIrBackendContext,
-    private val irNamer: IrNamer
+    private val irNamer: IrNamer,
+    val globalNameScope: NameScope
 ) : IrNamer by irNamer {
-
     val intrinsics = JsIntrinsicTransformers(backendContext)
     val classModels = mutableMapOf<IrClassSymbol, JsIrClassModel>()
     val coroutineImplDeclaration = backendContext.ir.symbols.coroutineImpl.owner

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/NameTables.kt

@@ -17,48 +17,53 @@ import org.jetbrains.kotlin.ir.expressions.IrWhen
 import org.jetbrains.kotlin.ir.types.isUnit
 import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
-import org.jetbrains.kotlin.ir.util.isEnumClass
 import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
-import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import org.jetbrains.kotlin.js.naming.isES5IdentifierPart
 import org.jetbrains.kotlin.js.naming.isES5IdentifierStart
 import org.jetbrains.kotlin.js.naming.isValidES5Identifier
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.utils.addToStdlib.ifNotEmpty
 import java.util.*
+import kotlin.collections.set
+import kotlin.math.abs
 
 // TODO remove direct usages of [mapToKey] from [NameTable] & co and move it to scripting & REPL infrastructure. Review usages.
 private fun <T> mapToKey(declaration: T): String {
     return with(JsManglerIr) {
         if (declaration is IrDeclaration) {
             declaration.hashedMangle.toString()
-        } else if (declaration is Signature) {
-            declaration.toString().hashMangle.toString()
+        } else if (declaration is String) {
+            declaration.hashMangle.toString()
         } else {
             error("Key is not generated for " + declaration?.let { it::class.simpleName })
         }
     }
 }
 
+abstract class NameScope {
+    abstract fun isReserved(name: String): Boolean
+
+    object EmptyScope : NameScope() {
+        override fun isReserved(name: String): Boolean = false
+    }
+}
+
 class NameTable<T>(
-    val parent: NameTable<*>? = null,
+    val parent: NameScope = EmptyScope,
     val reserved: MutableSet<String> = mutableSetOf(),
     val mappedNames: MutableMap<String, String>? = null
-) {
-    var finished = false
+) : NameScope() {
     val names = mutableMapOf<T, String>()
 
-    private fun isReserved(name: String): Boolean {
-        if (parent != null && parent.isReserved(name))
-            return true
-        return name in reserved
+    private val suggestedNameLastIdx = mutableMapOf<String, Int>()
+
+    override fun isReserved(name: String): Boolean {
+        return parent.isReserved(name) || name in reserved
     }
 
     fun declareStableName(declaration: T, name: String) {
-        if (parent != null) assert(parent.finished)
-        assert(!finished)
         names[declaration] = name
         reserved.add(name)
         mappedNames?.set(mapToKey(declaration), name)
@@ -74,7 +79,7 @@ class NameTable<T>(
         if (!isReserved(suggestedName))
             return suggestedName
 
-        var i = 0
+        var i = suggestedNameLastIdx[suggestedName] ?: 0
 
         fun freshName() =
             suggestedName + "_" + i
@@ -82,6 +87,9 @@ class NameTable<T>(
         while (isReserved(freshName())) {
             i++
         }
+
+        suggestedNameLastIdx[suggestedName] = i
+
         return freshName()
     }
 }
@@ -93,33 +101,25 @@ fun NameTable<IrDeclaration>.dump(): String =
         "---  $declRef => $name"
     }
 
-sealed class Signature
-data class StableNameSignature(val name: String) : Signature()
-data class BackingFieldSignature(val field: IrField) : Signature()
-data class ParameterTypeBasedSignature(val mangledName: String, val suggestedName: String) : Signature()
 
-fun fieldSignature(field: IrField): Signature {
-    if (field.isEffectivelyExternal()) {
-        return StableNameSignature(field.name.identifier)
-    }
+private const val RESERVED_MEMBER_NAME_SUFFIX = "_k$"
 
-    return BackingFieldSignature(field)
-}
-
-fun jsFunctionSignature(declaration: IrFunction, context: JsIrBackendContext?): Signature {
+fun jsFunctionSignature(declaration: IrFunction, context: JsIrBackendContext?): String {
     require(!declaration.isStaticMethodOfClass)
     require(declaration.dispatchReceiverParameter != null)
 
     val declarationName = declaration.getJsNameOrKotlinName().asString()
 
     if (declaration.hasStableJsName(context)) {
-        return StableNameSignature(declarationName)
+        // TODO: Handle reserved suffix in FE
+        require(!declarationName.endsWith(RESERVED_MEMBER_NAME_SUFFIX)) {
+            "Function ${declaration.fqNameWhenAvailable} uses reserved name suffix \"$RESERVED_MEMBER_NAME_SUFFIX\""
+        }
+        return declarationName
     }
 
     val nameBuilder = StringBuilder()
 
-    nameBuilder.append(declarationName)
-
     // TODO should we skip type parameters and use upper bound of type parameter when print type of value parameters?
     declaration.typeParameters.ifNotEmpty {
         nameBuilder.append("_\$t")
@@ -141,20 +141,19 @@ fun jsFunctionSignature(declaration: IrFunction, context: JsIrBackendContext?):
 
     val signature = nameBuilder.toString()
 
-    // TODO: Check reserved names
-    return ParameterTypeBasedSignature(signature, declarationName)
+    // TODO: Use better hashCode
+    return sanitizeName(declarationName) + "_" + abs(signature.hashCode()).toString(Character.MAX_RADIX) + RESERVED_MEMBER_NAME_SUFFIX
 }
 
 class NameTables(
-    packages: List<IrPackageFragment>,
+    packages: Iterable<IrPackageFragment>,
     reservedForGlobal: MutableSet<String> = mutableSetOf(),
     reservedForMember: MutableSet<String> = mutableSetOf(),
     val mappedNames: MutableMap<String, String>? = null,
     private val context: JsIrBackendContext? = null
 ) {
     val globalNames: NameTable<IrDeclaration>
-    private val memberNames: NameTable<Signature>
-    private val localNames = mutableMapOf<IrDeclaration, NameTable<IrDeclaration>>()
+    private val memberNames: NameTable<IrField>
     private val loopNames = mutableMapOf<IrLoop, String>()
 
     init {
@@ -171,74 +170,48 @@ class NameTables(
             mappedNames = mappedNames
         )
 
-        val classDeclaration = mutableListOf<IrClass>()
         for (p in packages) {
             for (declaration in p.declarations) {
-                generateNamesForTopLevelDecl(declaration)
+                processTopLevelLocalDecl(declaration)
+                processNonTopLevelLocalDecl(declaration)
+                declaration.acceptChildrenVoid(object : IrElementVisitorVoid {
+                    override fun visitElement(element: IrElement) {
+                        element.acceptChildrenVoid(this)
+                    }
+
+                    override fun visitDeclaration(declaration: IrDeclarationBase) {
+                        processNonTopLevelLocalDecl(declaration)
+                        super.visitDeclaration(declaration)
+                    }
+                })
                 if (declaration is IrScript) {
                     for (memberDecl in declaration.statements) {
                         if (memberDecl is IrDeclaration) {
-                            generateNamesForTopLevelDecl(memberDecl)
+                            processTopLevelLocalDecl(memberDecl)
                             if (memberDecl is IrClass) {
-                                classDeclaration += memberDecl
+                                processNonTopLevelLocalDecl(memberDecl)
                             }
                         }
                     }
                 }
             }
         }
+    }
 
-        globalNames.finished = true
-
-        for (declaration in classDeclaration) {
-            acceptDeclaration(declaration)
-        }
-
-        for (p in packages) {
-            for (declaration in p.declarations) {
-                acceptDeclaration(declaration)
+    private fun acceptNonExternalClass(declaration: IrClass) {
+        for (memberDecl in declaration.declarations) {
+            when (memberDecl) {
+                is IrField ->
+                    generateNameForMemberField(memberDecl)
             }
         }
     }
 
-    private fun acceptDeclaration(declaration: IrDeclaration) {
-        val localNameGenerator = LocalNameGenerator(declaration)
-
+    private fun processNonTopLevelLocalDecl(declaration: IrDeclaration) {
         if (declaration is IrClass) {
-            if (declaration.isEffectivelyExternal()) {
-                declaration.acceptChildrenVoid(object : IrElementVisitorVoid {
-                    override fun visitElement(element: IrElement) {
-                        element.acceptChildrenVoid(this)
-                    }
-
-                    override fun visitSimpleFunction(declaration: IrSimpleFunction) {
-                        val parent = declaration.parent
-                        if (parent is IrClass && !parent.isEnumClass) {
-                            generateNameForMemberFunction(declaration)
-                        }
-                    }
-
-                    override fun visitField(declaration: IrField) {
-                        val parent = declaration.parent
-                        if (parent is IrClass && !parent.isEnumClass) {
-                            generateNameForMemberField(declaration)
-                        }
-                    }
-                })
-            } else {
-                declaration.thisReceiver!!.acceptVoid(localNameGenerator)
-                for (memberDecl in declaration.declarations) {
-                    memberDecl.acceptChildrenVoid(LocalNameGenerator(memberDecl))
-                    when (memberDecl) {
-                        is IrSimpleFunction ->
-                            generateNameForMemberFunction(memberDecl)
-                        is IrField ->
-                            generateNameForMemberField(memberDecl)
-                    }
-                }
+            if (!declaration.isEffectivelyExternal()) {
+                acceptNonExternalClass(declaration)
             }
-        } else {
-            declaration.acceptChildrenVoid(localNameGenerator)
         }
     }
 
@@ -262,7 +235,6 @@ class NameTables(
 
         globalNames.names.addAllIfAbsent(table.globalNames.names)
         memberNames.names.addAllIfAbsent(table.memberNames.names)
-        localNames.addAllIfAbsent(table.localNames)
         loopNames.addAllIfAbsent(table.loopNames)
 
         globalNames.reserved.addAll(table.globalNames.reserved)
@@ -272,49 +244,23 @@ class NameTables(
     private fun generateNameForMemberField(field: IrField) {
         require(!field.isTopLevel)
         require(!field.isStatic)
-        val signature = fieldSignature(field)
 
         if (field.isEffectivelyExternal()) {
-            memberNames.declareStableName(signature, field.name.identifier)
+            memberNames.declareStableName(field, field.name.identifier)
         } else {
-            memberNames.declareFreshName(signature, "_" + sanitizeName(field.name.asString()))
-        }
-    }
-
-    private fun generateNameForMemberFunction(declaration: IrSimpleFunction) {
-        when (val signature = jsFunctionSignature(declaration, context)) {
-            is StableNameSignature -> memberNames.declareStableName(signature, signature.name)
-            is ParameterTypeBasedSignature -> memberNames.declareFreshName(signature, signature.suggestedName)
+            memberNames.declareFreshName(field, "_" + sanitizeName(field.name.asString()))
         }
     }
 
     @Suppress("unused")
     fun dump(): String {
-        val local = localNames.toList().joinToString("\n") { (decl, table) ->
-            val declRef = (decl as? IrDeclarationWithName)?.fqNameWhenAvailable ?: decl
-            "\nLocal names for $declRef:\n${table.dump()}\n"
-        }
-        return "Global names:\n${globalNames.dump()}" +
-                //   "\nMember names:\n${memberNames.dump()}" +
-                "\nLocal names:\n$local\n"
+        return "Global names:\n${globalNames.dump()}"
     }
 
     fun getNameForStaticDeclaration(declaration: IrDeclarationWithName): String {
         val global: String? = globalNames.names[declaration]
         if (global != null) return global
 
-        var parent: IrDeclarationParent = declaration.parent
-        while (parent is IrDeclaration) {
-            val parentLocalNames = localNames[parent]
-            if (parentLocalNames != null) {
-                val localName = parentLocalNames.names[declaration]
-                if (localName != null)
-                    return localName
-            }
-            parent = parent.parent
-        }
-
-
         mappedNames?.get(mapToKey(declaration))?.let {
             return it
         }
@@ -323,8 +269,7 @@ class NameTables(
     }
 
     fun getNameForMemberField(field: IrField): String {
-        val signature = fieldSignature(field)
-        val name = memberNames.names[signature] ?: mappedNames?.get(mapToKey(signature))
+        val name = memberNames.names[field] ?: mappedNames?.get(mapToKey(field))
 
         // TODO investigate
         if (name == null) {
@@ -334,24 +279,12 @@ class NameTables(
         return name
     }
 
-    fun getNameForMemberFunction(function: IrSimpleFunction): String {
-        val signature = jsFunctionSignature(function, context)
-        val name = memberNames.names[signature] ?: mappedNames?.get(mapToKey(signature))
-
-        // TODO Add a compiler flag, which enables this behaviour
-        // TODO remove in DCE
-        if (name == null) {
-            return sanitizeName(function.name.asString()) + "__error" // TODO one case is a virtual method of an abstract class with no implementation
-        }
-
-        return name
-    }
-
-    private fun generateNamesForTopLevelDecl(declaration: IrDeclaration) {
+    private fun processTopLevelLocalDecl(declaration: IrDeclaration) {
         when {
             declaration !is IrDeclarationWithName ->
                 return
 
+            // TODO: Handle JsQualifier
             declaration.isEffectivelyExternal() && (declaration.getJsModule() == null || declaration.isJsNonModule()) ->
                 globalNames.declareStableName(declaration, declaration.getJsNameOrKotlinName().identifier)
 
@@ -360,66 +293,59 @@ class NameTables(
         }
     }
 
-    inner class LocalNameGenerator(parentDeclaration: IrDeclaration) : IrElementVisitorVoid {
-        val table = NameTable<IrDeclaration>(globalNames)
+}
 
-        private val breakableDeque: Deque<IrExpression> = LinkedList()
+class LocalNameGenerator(parentScope: NameScope) : IrElementVisitorVoid {
+    val variableNames = NameTable<IrDeclarationWithName>(parentScope)
+    val localLoopNames = NameTable<IrLoop>()
 
-        init {
-            localNames[parentDeclaration] = table
-        }
+    private val breakableDeque: Deque<IrExpression> = LinkedList()
 
-        private val localLoopNames = NameTable<IrLoop>()
-        override fun visitElement(element: IrElement) {
-            element.acceptChildrenVoid(this)
-        }
+    override fun visitElement(element: IrElement) {
+        element.acceptChildrenVoid(this)
+    }
 
-        override fun visitDeclaration(declaration: IrDeclarationBase) {
-            if (declaration is IrDeclarationWithName) {
-                table.declareFreshName(declaration, declaration.name.asString())
-            }
-            super.visitDeclaration(declaration)
-        }
-
-        override fun visitBreak(jump: IrBreak) {
-            val loop = jump.loop
-            if (loop.label == null && loop != breakableDeque.firstOrNull()) {
-                persistLoopName(SYNTHETIC_LOOP_LABEL, loop)
-            }
-
-            super.visitBreak(jump)
-        }
-
-        override fun visitWhen(expression: IrWhen) {
-            breakableDeque.push(expression)
-
-            super.visitWhen(expression)
-
-            breakableDeque.pop()
-        }
-
-        override fun visitLoop(loop: IrLoop) {
-            breakableDeque.push(loop)
-
-            super.visitLoop(loop)
-
-            breakableDeque.pop()
-
-            val label = loop.label
-
-            if (label != null) {
-                persistLoopName(label, loop)
-            }
-        }
-
-        private fun persistLoopName(label: String, loop: IrLoop) {
-            localLoopNames.declareFreshName(loop, label)
-            loopNames[loop] = localLoopNames.names[loop]!!
+    override fun visitDeclaration(declaration: IrDeclarationBase) {
+        super.visitDeclaration(declaration)
+        if (declaration is IrDeclarationWithName) {
+            variableNames.declareFreshName(declaration, declaration.name.asString())
         }
     }
 
-    fun getNameForLoop(loop: IrLoop): String? =
-        loopNames[loop]
+    override fun visitBreak(jump: IrBreak) {
+        val loop = jump.loop
+        if (loop.label == null && loop != breakableDeque.firstOrNull()) {
+            persistLoopName(SYNTHETIC_LOOP_LABEL, loop)
+        }
+
+        super.visitBreak(jump)
+    }
+
+    override fun visitWhen(expression: IrWhen) {
+        breakableDeque.push(expression)
+
+        super.visitWhen(expression)
+
+        breakableDeque.pop()
+    }
+
+    override fun visitLoop(loop: IrLoop) {
+        breakableDeque.push(loop)
+
+        super.visitLoop(loop)
+
+        breakableDeque.pop()
+
+        val label = loop.label
+
+        if (label != null) {
+            persistLoopName(label, loop)
+        }
+    }
+
+    private fun persistLoopName(label: String, loop: IrLoop) {
+        localLoopNames.declareFreshName(loop, label)
+    }
 }
 
 
@@ -427,8 +353,17 @@ fun sanitizeName(name: String): String {
     if (name.isValidES5Identifier()) return name
     if (name.isEmpty()) return "_"
 
+    val builder = StringBuilder()
+
     val first = name.first().let { if (it.isES5IdentifierStart()) it else '_' }
-    return first.toString() + name.drop(1).map { if (it.isES5IdentifierPart()) it else '_' }.joinToString("")
+    builder.append(first)
+
+    for (idx in 1..name.lastIndex) {
+        val c = name[idx]
+        builder.append(if (c.isES5IdentifierPart()) c else '_')
+    }
+
+    return builder.toString()
 }
 
 private const val SYNTHETIC_LOOP_LABEL = "\$l\$break"

js/js.frontend/src/org/jetbrains/kotlin/js/naming/NameSuggestion.kt

@@ -399,7 +399,6 @@ fun Char.isES5IdentifierPart(): Boolean {
                 Character.CONNECTOR_PUNCTUATION -> true
                 else -> false
             } ||
-            // Nl which is missing in Character.isLetter, but present in UnicodeLetter in spec
             this == '\u200C' ||   // Zero-width non-joiner
             this == '\u200D'      // Zero-width joiner
 }