Added StringTrimLowering to pipeline (#4647)

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/KonanLoweringPhases.kt

@@ -380,3 +380,9 @@ internal val foldConstantLoweringPhase = makeKonanFileOpPhase(
         description = "Constant Folding",
         prerequisite = setOf(flattenStringConcatenationPhase)
 )
+
+internal val computeStringTrimPhase = makeKonanFileLoweringPhase(
+        ::StringTrimLowering,
+        name = "StringTrimLowering",
+        description = "Compute trimIndent and trimMargin operations on constant strings"
+)

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ToplevelPhases.kt

@@ -221,6 +221,7 @@ internal val allLoweringsPhase = NamedCompilerPhase(
                             forLoopsPhase,
                             flattenStringConcatenationPhase,
                             foldConstantLoweringPhase,
+                            computeStringTrimPhase,
                             stringConcatenationPhase,
                             enumConstructorsPhase,
                             initializersPhase,

kotlin-native/backend.native/tests/build.gradle

@@ -813,6 +813,10 @@ task hello0(type: KonanLocalTest) {
     source = "runtime/basic/hello0.kt"
 }
 
+task stringTrim(type: KonanLocalTest) {
+    source = "codegen/stringTrim/stringTrim.kt"
+}
+
 standaloneTest("hello1") {
    goldValue = "Hello World"
    testData = "Hello World\n"

kotlin-native/backend.native/tests/codegen/stringTrim/stringTrim.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package codegen.stringTrim.stringTrim
+
+import kotlin.test.*
+
+// TODO: check IR
+fun constantIndent(): String {
+    return """
+        Hello,
+        World
+    """.trimIndent()
+}
+
+fun constantMargin(): String {
+    return """
+        |Hello,
+        |World
+    """.trimMargin()
+}
+
+@Test
+fun runTest() {
+    assertTrue(constantIndent() === constantIndent())
+    assertTrue(constantMargin() === constantMargin())
+}
+