IR lowering for computing trimIndent/trimMargin on constants

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

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. 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.common.lower
+
+import org.jetbrains.kotlin.backend.common.CommonBackendContext
+import org.jetbrains.kotlin.backend.common.FileLoweringPass
+import org.jetbrains.kotlin.backend.common.lower.matchers.SimpleCalleeMatcher
+import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
+import org.jetbrains.kotlin.ir.declarations.IrFile
+import org.jetbrains.kotlin.ir.expressions.IrCall
+import org.jetbrains.kotlin.ir.expressions.IrConst
+import org.jetbrains.kotlin.ir.expressions.IrConstKind
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
+import org.jetbrains.kotlin.ir.types.isString
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+import org.jetbrains.kotlin.name.FqName
+
+val computeStringTrimPhase = makeIrFilePhase(
+    ::StringTrimLowering,
+    name = "StringTrimLowering",
+    description = "Compute trimIndent and trimMargin operations on constant strings"
+)
+
+class StringTrimLowering(val context: CommonBackendContext) : FileLoweringPass, IrElementTransformerVoid() {
+    override fun lower(irFile: IrFile) {
+        irFile.transformChildrenVoid(this)
+    }
+
+    override fun visitCall(expression: IrCall): IrExpression {
+        return when {
+            trimIndentMatcher(expression) -> maybeComputeTrimIndent(expression)
+            trimMarginMatcher(expression) -> maybeComputeTrimMargin(expression)
+            else -> super.visitCall(expression)
+        }
+    }
+
+    private fun maybeComputeTrimIndent(call: IrCall): IrExpression {
+        val receiverString = call.extensionReceiver!!.getConstantString() ?: return call
+        val newString = receiverString.trimIndent()
+        return IrConstImpl.string(call.startOffset, call.endOffset, call.type, newString)
+    }
+
+    private fun maybeComputeTrimMargin(call: IrCall): IrExpression {
+        val receiverString = call.extensionReceiver!!.getConstantString() ?: return call
+
+        val prefixArgument = call.getValueArgument(0)
+        val newString = if (prefixArgument != null) {
+            val prefixString = prefixArgument.getConstantString() ?: return call
+            receiverString.trimMargin(prefixString)
+        } else {
+            receiverString.trimMargin()
+        }
+
+        return IrConstImpl.string(call.startOffset, call.endOffset, call.type, newString)
+    }
+
+    companion object {
+        private fun IrExpression.getConstantString(): String? {
+            if (this is IrConst<*> && kind == IrConstKind.String) {
+                return IrConstKind.String.valueOf(this)
+            }
+            return null
+        }
+
+        private val trimIndentMatcher = SimpleCalleeMatcher {
+            extensionReceiver { it != null && it.type.isString() }
+            fqName { it == TRIM_INDENT_FQ_NAME }
+            parameterCount { it == 0 }
+        }
+
+        private val trimMarginMatcher = SimpleCalleeMatcher {
+            extensionReceiver { it != null && it.type.isString() }
+            fqName { it == TRIM_MARGIN_FQ_NAME }
+            parameterCount { it == 1 }
+            parameter(0) { it.type.isString() }
+        }
+
+        private val TRIM_MARGIN_FQ_NAME = FqName.fromSegments(listOf("kotlin", "text", "trimMargin"))
+        private val TRIM_INDENT_FQ_NAME = FqName.fromSegments(listOf("kotlin", "text", "trimIndent"))
+    }
+}

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt

@@ -114,6 +114,7 @@ val jvmPhases = namedIrFilePhase<JvmBackendContext>(
             toArrayPhase then
             flattenStringConcatenationPhase then
             foldConstantLoweringPhase then
+            computeStringTrimPhase then
             jvmBuiltinOptimizationLoweringPhase then
             additionalClassAnnotationPhase then
 

compiler/testData/codegen/bytecodeText/intrinsicsTrim/trimIndentPositive.kt

@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
-
 fun constant(): String {
     return """
         Hello,
@@ -17,6 +15,17 @@ fun interpolatedUsingConstant(): String {
     """.trimIndent()
 }
 
+private const val SPACES = "    "
+private const val HELLO = "Hello"
+private const val WORLD = "World"
+fun reliesOnNestedStringBuilderFlatteningAndConstantConcatenation(): String {
+    return ("" + '\n' + SPACES + "${SPACES}Hey" + """
+        ${HELLO + HELLO},
+        ${WORLD + WORLD}
+""" + SPACES).trimIndent()
+}
+
 // 1 LDC "Hello,\\nWorld"
 // 1 LDC "Hello,\\nHello,\\nWorld\\nWorld"
+// 1 LDC "Hey\\nHelloHello,\\nWorldWorld"
 // 0 INVOKESTATIC kotlin/text/StringsKt.trimIndent

compiler/testData/codegen/bytecodeText/intrinsicsTrim/trimMarginPositive.kt

@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
-
 fun constant(): String {
     return """
         |Hello,
@@ -17,6 +15,17 @@ fun interpolatedUsingConstant(): String {
     """.trimMargin()
 }
 
+
+private const val SPACES = "    "
+private const val HELLO = "Hello"
+private const val WORLD = "World"
+fun reliesOnNestedStringBuilderFlatteningAndConstantConcatenation(): String {
+    return ("" + '\n' + SPACES + "${SPACES}|Hey" + """
+        |${HELLO + HELLO},
+        |${WORLD + WORLD}
+""" + SPACES).trimMargin()
+}
+
 fun constantCustomPrefix(): String {
     return """
         ###Hello,
@@ -34,5 +43,6 @@ fun constantCustomPrefixInterpolatedUsingConstant(): String {
 
 // 3 LDC "Hello,\\nWorld"
 // 1 LDC "Hello,\\nHello,\\nWorld\\nWorld"
+// 1 LDC "Hey\\nHelloHello,\\nWorldWorld"
 // 0 LDC "###"
 // 0 INVOKESTATIC kotlin/text/StringsKt.trimMargin