[Wasm] Use common StringConcatenationLowering

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt

@@ -56,7 +56,7 @@ private val expectDeclarationsRemovingPhase = makeWasmModulePhase(
 )
 
 private val stringConstructorLowering = makeWasmModulePhase(
-    ::SimpleStringConcatenationLowering,
+    ::StringConcatenationLowering,
     name = "StringConcatenation",
     description = "String concatenation lowering"
 )

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmSymbols.kt

@@ -53,8 +53,8 @@ class WasmSymbols(
         getIrClass(FqName("kotlin.wasm.internal.DefaultConstructorMarker"))
     override val throwKotlinNothingValueException: IrSimpleFunctionSymbol
         get() = TODO()
-    override val stringBuilder
-        get() = TODO()
+    override val stringBuilder =
+        getIrClass(FqName("kotlin.text.StringBuilder"))
     override val coroutineImpl
         get() = TODO()
     override val coroutineSuspendedGetter

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/SimpleStringConcatenationLowering.kt

@@ -1,91 +0,0 @@
-/*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.backend.wasm.lower
-
-import org.jetbrains.kotlin.backend.common.FileLoweringPass
-import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
-import org.jetbrains.kotlin.backend.common.lower.DeclarationIrBuilder
-import org.jetbrains.kotlin.backend.common.lower.at
-import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
-import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
-import org.jetbrains.kotlin.ir.builders.irCall
-import org.jetbrains.kotlin.ir.builders.irString
-import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrFunction
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
-import org.jetbrains.kotlin.ir.expressions.IrExpression
-import org.jetbrains.kotlin.ir.expressions.IrStringConcatenation
-import org.jetbrains.kotlin.ir.types.getClass
-import org.jetbrains.kotlin.ir.types.isNullable
-import org.jetbrains.kotlin.ir.types.isString
-import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
-import org.jetbrains.kotlin.name.Name
-
-/**
- * Replace string concatenation with a chain of String.plus calls.
- * TODO: Reuse common StringConcatenationLowering which uses string builder
- */
-class SimpleStringConcatenationLowering(val context: WasmBackendContext) : FileLoweringPass {
-    override fun lower(irFile: IrFile) {
-        irFile.transformChildrenVoid(StringConcatenationTransformer(this))
-    }
-}
-
-private class StringConcatenationTransformer(val lower: SimpleStringConcatenationLowering) : IrElementTransformerVoidWithContext() {
-    private val context = lower.context
-    private val irBuiltIns = context.irBuiltIns
-    private val stringPlus = irBuiltIns.stringClass.owner.declarations.filterIsInstance<IrSimpleFunction>().find {
-        it.name == Name.identifier("plus")
-    }!!
-
-    private val anyToString = irBuiltIns.anyClass.owner.declarations.filterIsInstance<IrSimpleFunction>().find {
-        it.name == Name.identifier("toString")
-    }!!
-
-    private val anyNToString = context.wasmSymbols.anyNtoString
-
-
-    override fun visitStringConcatenation(expression: IrStringConcatenation): IrExpression {
-        val transformed = super.visitStringConcatenation(expression) as IrStringConcatenation
-        val builder: DeclarationIrBuilder = context.createIrBuilder(currentScope!!.scope.scopeOwnerSymbol).at(expression)
-        return transformed.arguments.fold<IrExpression, IrExpression>(
-            builder.irString("")
-        ) { acc, el ->
-            builder.irCall(stringPlus).apply {
-                dispatchReceiver = acc
-                putValueArgument(0, expressionToString(el, builder))
-            }
-        }
-    }
-
-    private fun expressionToString(expression: IrExpression, builder: DeclarationIrBuilder): IrExpression {
-        if (expression.type.isString()) return expression
-        builder.at(expression)
-        val klass = expression.type.getClass()
-
-        if (expression.type.isNullable()) {
-            return builder.irCall(anyNToString).apply {
-                putValueArgument(0, expression)
-            }
-        }
-
-        val toStringMethod: IrSimpleFunction = if (klass != null) {
-            klass.declarations.filterIsInstance<IrSimpleFunction>().find { it.isToStringInheritedFromAny() }!!
-        } else {
-            anyToString
-        }
-
-        return builder.irCall(toStringMethod).apply {
-            dispatchReceiver = expression
-        }
-    }
-}
-
-fun IrFunction.isToStringInheritedFromAny() =
-    name == Name.identifier("toString") &&
-            dispatchReceiverParameter != null &&
-            extensionReceiverParameter == null &&
-            valueParameters.isEmpty()