[JS IR] Introduce intrinsics for slicing array-like objects

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

@@ -242,6 +242,13 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
     val jsClass = getInternalFunction("jsClassIntrinsic")
     val arrayLiteral: IrSimpleFunctionSymbol = getInternalFunction("arrayLiteral")
 
+    // The following 3 functions are all lowered into [].slice.call(...), they only differ
+    // in the number of arguments.
+    // See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
+    val jsArrayLike2Array = getInternalFunction("jsArrayLike2Array")
+    val jsSliceArrayLikeFromIndex = getInternalFunction("jsSliceArrayLikeFromIndex")
+    val jsSliceArrayLikeFromIndexToIndex = getInternalFunction("jsSliceArrayLikeFromIndexToIndex")
+
     internal inner class JsReflectionSymbols : ReflectionSymbols {
         override val createKType = getInternalWithoutPackageOrNull("createKType")
         override val createDynamicKType = getInternalWithoutPackageOrNull("createDynamicKType")

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsIntrinsicTransformers.kt

@@ -154,6 +154,17 @@ class JsIntrinsicTransformers(backendContext: JsIrBackendContext) {
                 translateCallArguments(call, context).single()
             }
 
+            for (intrinsic in arrayOf(
+                intrinsics.jsArrayLike2Array,
+                intrinsics.jsSliceArrayLikeFromIndex,
+                intrinsics.jsSliceArrayLikeFromIndexToIndex
+            )) {
+                add(intrinsic) { call, context ->
+                    val args = translateCallArguments(call, context)
+                    JsInvocation(JsNameRef(Namer.CALL_FUNCTION, JsNameRef(Namer.SLICE_FUNCTION, JsArrayLiteral())), args)
+                }
+            }
+
             add(intrinsics.jsArraySlice) { call, context ->
                 JsInvocation(JsNameRef(Namer.SLICE_FUNCTION, translateCallArguments(call, context).single()))
             }

libraries/stdlib/js-ir/runtime/jsIntrinsics.kt

@@ -192,6 +192,15 @@ internal fun jsBind(receiver: Any?, target: Any?): Any?
 @JsIntrinsic
 internal fun <A> slice(a: A): A
 
+@JsIntrinsic
+internal fun <T> jsArrayLike2Array(arrayLike: Any?): Array<T>
+
+@JsIntrinsic
+internal fun <T> jsSliceArrayLikeFromIndex(arrayLike: Any?, start: Int): Array<T>
+
+@JsIntrinsic
+internal fun <T> jsSliceArrayLikeFromIndexToIndex(arrayLike: Any?, start: Int, end: Int): Array<T>
+
 @JsIntrinsic
 internal fun unreachable(): Nothing