Flatten nested string concatenation expressions into a single IrStringConcatenation, in a separate lowering phase.
Consolidating these into IrStringConcatenations allows the backend to produce efficient code for string concatenations (e.g., using StringBuilder for JVM).
This commit is contained in:
Mark Punzalan
committed by
max-kammerer
max-kammerer
parent
ae22bdee15
commit
d4d5a6011c
+143
@@ -0,0 +1,143 @@
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/*
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* Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
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* that can be found in the license/LICENSE.txt file.
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*/
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package org.jetbrains.kotlin.backend.common.lower
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import org.jetbrains.kotlin.backend.common.CommonBackendContext
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import org.jetbrains.kotlin.backend.common.FileLoweringPass
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import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
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import org.jetbrains.kotlin.ir.IrElement
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import org.jetbrains.kotlin.ir.declarations.IrFile
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import org.jetbrains.kotlin.ir.expressions.IrCall
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import org.jetbrains.kotlin.ir.expressions.IrExpression
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import org.jetbrains.kotlin.ir.expressions.IrStringConcatenation
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import org.jetbrains.kotlin.ir.expressions.impl.IrStringConcatenationImpl
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import org.jetbrains.kotlin.ir.types.isString
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import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
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import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
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import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
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import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
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import org.jetbrains.kotlin.name.Name
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val flattenStringConcatenationPhase = makeIrFilePhase(
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::FlattenStringConcatenationLowering,
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name = "FlattenStringConcatenationLowering",
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description = "Flatten nested string concatenation expressions into a single IrStringConcatenation"
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)
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/**
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* Flattens nested string concatenation expressions into a single [IrStringConcatenation]. Consolidating these into IrStringConcatenations
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* allows the backend to produce efficient code for string concatenations (e.g., using StringBuilder for JVM).
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*
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* Example expression:
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*
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* val s = "1" + 2 + ("s1: '$s1'" + 3.0 + null)
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*
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* IR before lowering:
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*
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* VAR name:s type:kotlin.String flags:val
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* CALL 'plus(Any?): String' type=kotlin.String origin=PLUS
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* $this: CALL 'plus(Any?): String' type=kotlin.String origin=PLUS
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* $this: CONST String type=kotlin.String value="1"
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* other: CONST Int type=kotlin.Int value=2
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* other: CALL 'plus(Any?): String' type=kotlin.String origin=PLUS
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* $this: CALL 'plus(Any?): String' type=kotlin.String origin=PLUS
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* $this: STRING_CONCATENATION type=kotlin.String
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* CONST String type=kotlin.String value="s1: '"
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* GET_VAR 's1: String' type=kotlin.String origin=null
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* CONST String type=kotlin.String value="'"
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* other: CONST Double type=kotlin.Double value=3.0
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* other: CONST Null type=kotlin.Nothing? value=null
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*
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* IR after lowering:
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*
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* VAR name:s type:kotlin.String flags:val
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* STRING_CONCATENATION type=kotlin.String
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* CONST String type=kotlin.String value="1"
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* CONST Int type=kotlin.Int value=2
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* CONST String type=kotlin.String value="s1: '"
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* GET_VAR 's1: String' type=kotlin.String origin=null
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* CONST String type=kotlin.String value="'"
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* CONST Double type=kotlin.Double value=3.0
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* CONST Null type=kotlin.Nothing? value=null
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*/
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class FlattenStringConcatenationLowering(val context: CommonBackendContext) : FileLoweringPass, IrElementTransformerVoid() {
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companion object {
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private val PLUS_NAME = Name.identifier("plus")
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/** @return true if the given expression is a [IrStringConcatenation] or [String.plus] [IrCall]. */
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private fun isStringConcatenationExpression(expression: IrExpression): Boolean {
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return when (expression) {
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is IrStringConcatenation -> true
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is IrCall -> {
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val dispatchReceiver = expression.dispatchReceiver
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dispatchReceiver != null &&
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dispatchReceiver.type.isString() &&
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expression.symbol.owner.name == PLUS_NAME &&
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expression.type.isString() &&
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expression.valueArgumentsCount == 1
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}
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else -> false
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}
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}
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/** Recursively collects string concatenation arguments from the given expression. */
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private fun collectStringConcatenationArguments(expression: IrExpression): List<IrExpression> {
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val arguments = mutableListOf<IrExpression>()
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expression.acceptChildrenVoid(object : IrElementVisitorVoid {
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override fun visitElement(element: IrElement) {
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// Theoretically this is unreachable code since all descendants of IrExpressions are IrExpressions.
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element.acceptChildrenVoid(this)
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}
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override fun visitCall(expression: IrCall) {
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if (isStringConcatenationExpression(expression)) {
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// Recursively collect from call arguments.
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expression.acceptChildrenVoid(this)
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} else {
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// Add call itself as an argument.
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arguments.add(expression)
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}
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}
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override fun visitStringConcatenation(expression: IrStringConcatenation) {
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// Recursively collect from concatenation arguments.
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expression.acceptChildrenVoid(this)
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}
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override fun visitExpression(expression: IrExpression) {
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// These IrExpressions are neither IrCalls nor IrStringConcatenations and should be added as an argument.
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arguments.add(expression)
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}
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})
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return arguments
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}
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}
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override fun lower(irFile: IrFile) {
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irFile.transformChildrenVoid(this)
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}
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override fun visitExpression(expression: IrExpression): IrExpression {
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// Only modify/flatten string concatenation expressions.
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val transformedExpression =
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if (isStringConcatenationExpression(expression))
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expression.run {
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IrStringConcatenationImpl(
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startOffset,
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endOffset,
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type,
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collectStringConcatenationArguments(this)
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)
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}
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else expression
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transformedExpression.transformChildrenVoid(this)
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return transformedExpression
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}
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}
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@@ -82,6 +82,7 @@ internal val jvmPhases = namedIrFilePhase(
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tailrecPhase then
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toArrayPhase then
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jvmTypeOperatorLoweringPhase then
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flattenStringConcatenationPhase then
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jvmBuiltinOptimizationLoweringPhase then
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makePatchParentsPhase(3)
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+19
-7
@@ -858,14 +858,26 @@ class ExpressionCodegen(
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override fun visitStringConcatenation(expression: IrStringConcatenation, data: BlockInfo): StackValue {
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expression.markLineNumber(startOffset = true)
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AsmUtil.genStringBuilderConstructor(mv)
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expression.arguments.forEach {
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val stackValue = gen(it, data)
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AsmUtil.genInvokeAppendMethod(mv, stackValue.type, stackValue.kotlinType)
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return when (expression.arguments.size) {
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0 -> StackValue.constant("", expression.asmType)
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1 -> {
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// Convert single arg to string.
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val arg = expression.arguments[0]
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val argStackValue = gen(arg, arg.asmType, data)
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AsmUtil.genToString(argStackValue, argStackValue.type, argStackValue.kotlinType, typeMapper).put(expression.asmType, mv)
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expression.onStack
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}
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else -> {
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// Use StringBuilder to concatenate.
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AsmUtil.genStringBuilderConstructor(mv)
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expression.arguments.forEach {
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val stackValue = gen(it, data)
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AsmUtil.genInvokeAppendMethod(mv, stackValue.type, stackValue.kotlinType)
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}
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mv.invokevirtual("java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false)
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expression.onStack
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}
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}
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mv.invokevirtual("java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false)
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return expression.onStack
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}
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override fun visitWhileLoop(loop: IrWhileLoop, data: BlockInfo): StackValue {
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+22
-2
@@ -8,14 +8,34 @@ fun test1(s1: String, s2: String, s3: String) =
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fun test2(s1: String, s2: String, s3: String) =
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s1 + (s2 + s3)
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fun test3(s1: String, s2: String, s3: String) =
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fun test3(s1: String, s2: String, s3: String, s4: String) =
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((s1 + s2) + ((s3 + s4)))
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fun test4(s1: String, s2: String, s3: String) =
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"s1: $s1; " +
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"s2: $s2; " +
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"s3: $s3"
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fun test5(s1: String, s2: String, s3: String) =
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"${"s1:" + "${" " + s1};"} " +
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"${"s2:" + "${" " + s2};"} " +
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"${"s3:" + "${" " + s3}"}"
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fun test6(s1: String, s2: String, s3: String) =
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"${"s1:" + "${" " + s1};"} ${"s2:" + "${" " + s2};"} ${"s3:" + "${" " + s3}"}"
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fun test7(s1: String, s2: String, s3: String): String {
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fun foo(s: String) = s
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return "foo: " + foo(s1 + s2 + " ${foo("\${s3.length} = ${s3.length}")}")
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}
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fun box(): String {
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assertEquals("123", test1("1", "2", "3"))
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assertEquals("123", test2("1", "2", "3"))
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assertEquals("s1: 1; s2: 2; s3: 3", test3("1", "2", "3"))
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assertEquals("1234", test3("1", "2", "3", "4"))
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assertEquals("s1: 1; s2: 2; s3: 3", test4("1", "2", "3"))
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assertEquals("s1: 1; s2: 2; s3: 3", test5("1", "2", "3"))
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assertEquals("s1: 1; s2: 2; s3: 3", test6("1", "2", "3"))
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assertEquals("foo: 12 \${s3.length} = 1", test7("1", "2", "3"))
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return "OK"
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}
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@@ -1,4 +1,3 @@
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// IGNORE_BACKEND: JVM_IR
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class A() {
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override fun toString(): String {
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@@ -1,16 +1,41 @@
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// IGNORE_BACKEND: JVM_IR
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// Uses 1 StringBuilder
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fun test1(s1: String, s2: String, s3: String) =
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(s1 + s2) + s3
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// Uses 1 StringBuilder
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fun test2(s1: String, s2: String, s3: String) =
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s1 + (s2 + s3)
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// Uses 1 StringBuilder
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fun test3(s1: String, s2: String, s3: String, s4: String) =
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((s1 + s2) + ((s3 + s4)))
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// Combination of String.plus and string literal
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// Uses 1 StringBuilder
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fun test4(s1: String, s2: String, s3: String) =
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"s1: $s1; " +
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"s2: $s2; " +
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"s3: $s3"
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// 4 NEW java/lang/StringBuilder
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// Combination of String.plus and nested string literal
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// Uses 1 StringBuilder
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fun test5(s1: String, s2: String, s3: String) =
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"${"s1:" + "${" " + s1};"}; " +
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"${"s2:" + "${" " + s2};"}; " +
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"${"s3:" + "${" " + s3}"}"
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// Top-level string concatenation element is a string literal
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// Uses 1 StringBuilder
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fun test6(s1: String, s2: String, s3: String) =
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"${"s1:" + "${" " + s1};"} ${"s2:" + "${" " + s2};"} ${"s3:" + "${" " + s3}"}"
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// Uses 3 StringBuilders:
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// - In return expression
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// - In argument to 1st call to foo()
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// - In argument to 2nd call to foo() inside string literal
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fun test7(s1: String, s2: String, s3: String): String {
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fun foo(s: String) = s
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return "foo: " + foo(s1 + s2 + " ${foo("\${s3.length} = ${s3.length}")}")
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}
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// 9 NEW java/lang/StringBuilder
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@@ -1,4 +1,3 @@
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// IGNORE_BACKEND: JVM_IR
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class A() {
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override fun toString(): String {
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-1
@@ -1,4 +1,3 @@
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// IGNORE_BACKEND: JVM_IR
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fun test(b: Byte, s: Short, i: Int, l: Long) {
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"$b"
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"$s"
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