[JS IR] Optimize JS AST for closures

^KT-58891 Fixed

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/optimizations.kt

@@ -30,6 +30,7 @@ fun optimizeProgramByIr(
 fun optimizeFragmentByJsAst(fragment: JsIrProgramFragment) {
     val optimizer = object : RecursiveJsVisitor() {
         override fun visitFunction(x: JsFunction) {
+            super.visitFunction(x)
             FunctionPostProcessor(x).apply()
         }
 

js/js.tests/test/org/jetbrains/kotlin/js/testOld/optimizer/DeadCodeEliminationTest.kt

@@ -19,5 +19,9 @@ package org.jetbrains.kotlin.js.testOld.optimizer
 import org.junit.Test
 
 class DeadCodeEliminationTest : BasicOptimizerTest("dead-code-elimination") {
-    @Test fun switchCases() = box()
+    @Test
-}
+    fun switchCases() = box()
+
+    @Test
+    fun afterReturn() = box()
+}

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirJsBoxTestGenerated.java

@@ -6928,6 +6928,12 @@ public class FirJsBoxTestGenerated extends AbstractFirJsBoxTest {
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/jsAstOptimizations"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS_IR, true);
         }
 
+        @Test
+        @TestMetadata("deadCodeElimination.kt")
+        public void testDeadCodeElimination() throws Exception {
+            runTest("js/js.translator/testData/box/jsAstOptimizations/deadCodeElimination.kt");
+        }
+
         @Test
         @TestMetadata("tempVarDeclOnAssignment.kt")
         public void testTempVarDeclOnAssignment() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsES6TestGenerated.java

@@ -7034,6 +7034,12 @@ public class IrBoxJsES6TestGenerated extends AbstractIrBoxJsES6Test {
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/jsAstOptimizations"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS_IR_ES6, true);
         }
 
+        @Test
+        @TestMetadata("deadCodeElimination.kt")
+        public void testDeadCodeElimination() throws Exception {
+            runTest("js/js.translator/testData/box/jsAstOptimizations/deadCodeElimination.kt");
+        }
+
         @Test
         @TestMetadata("tempVarDeclOnAssignment.kt")
         public void testTempVarDeclOnAssignment() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java

@@ -6928,6 +6928,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/jsAstOptimizations"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS_IR, true);
         }
 
+        @Test
+        @TestMetadata("deadCodeElimination.kt")
+        public void testDeadCodeElimination() throws Exception {
+            runTest("js/js.translator/testData/box/jsAstOptimizations/deadCodeElimination.kt");
+        }
+
         @Test
         @TestMetadata("tempVarDeclOnAssignment.kt")
         public void testTempVarDeclOnAssignment() throws Exception {

js/js.translator/testData/box/jsAstOptimizations/deadCodeElimination.kt

@@ -0,0 +1,23 @@
+// IGNORE_BACKEND_K2: JS_IR
+// FIR works fine, however it generates another names for the temporary variables, therefore ignore it
+
+fun demo(f: () -> String) = f()
+
+// EXPECT_GENERATED_JS: function=test$lambda expect=deadCodeEliminationTestLambda.js
+fun test(x: String?): String {
+    val r = demo {
+        val z = x ?: run {
+            return@demo "OK"
+        }
+        "Fail 1: $z"
+    }
+    return r
+}
+
+fun box(): String {
+    val r = test(null)
+    if (r != "OK") {
+        return "Fail test, got $r"
+    }
+    return "OK"
+}

js/js.translator/testData/box/jsAstOptimizations/deadCodeEliminationTestLambda.js

@@ -0,0 +1,15 @@
+function test$lambda($x) {
+  return function () {
+    var tmp0_elvis_lhs = $x;
+    var tmp;
+    if (tmp0_elvis_lhs == null) {
+      // Inline function 'kotlin.run' call
+      // Inline function 'kotlin.contracts.contract' call
+      return 'OK';
+    } else {
+      tmp = tmp0_elvis_lhs;
+    }
+    var z = tmp;
+    return 'Fail 1: ' + z;
+  };
+}

js/js.translator/testData/js-optimizer/dead-code-elimination/afterReturn.optimized.js

@@ -0,0 +1,34 @@
+function test1(x) {
+    var $tmp;
+    if (x == null) {
+        return 'OK';
+    } else {
+        $tmp = x;
+    }
+    var z = $tmp;
+    return 'Fail 1: ' + z;
+}
+
+function test2(x) {
+    return function () {
+        var $tmp0_elvis_lhs = x;
+        var $tmp;
+        if ($tmp0_elvis_lhs == null) {
+            return 'OK';
+        } else {
+            $tmp = $tmp0_elvis_lhs;
+        }
+        var z = $tmp;
+        return 'Fail 1: ' + z;
+    }
+}
+
+function box() {
+    if (test1(null) != "OK") {
+        return "Fail test1";
+    }
+    if (test2(null)() != "OK") {
+        return "Fail test2";
+    }
+    return "OK"
+}

js/js.translator/testData/js-optimizer/dead-code-elimination/afterReturn.original.js

@@ -0,0 +1,39 @@
+function test1(x) {
+    var $tmp0_elvis_lhs = x;
+    var $tmp;
+    if ($tmp0_elvis_lhs == null) {
+        var $tmp$ret$0;
+        return 'OK';
+        $tmp = $tmp$ret$0;
+    } else {
+        $tmp = $tmp0_elvis_lhs;
+    }
+    var z = $tmp;
+    return 'Fail 1: ' + z;
+}
+
+function test2(x) {
+    return function () {
+        var $tmp0_elvis_lhs = x;
+        var $tmp;
+        if ($tmp0_elvis_lhs == null) {
+            var $tmp$ret$0;
+            return 'OK';
+            $tmp = $tmp$ret$0;
+        } else {
+            $tmp = $tmp0_elvis_lhs;
+        }
+        var z = $tmp;
+        return 'Fail 1: ' + z;
+    }
+}
+
+function box() {
+    if (test1(null) != "OK") {
+        return "Fail test1";
+    }
+    if (test2(null)() != "OK") {
+        return "Fail test2";
+    }
+    return "OK"
+}