[Wasm] Improve class type checks

Use wasm ref.test instad of manual type info linked list traversal

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmSymbols.kt

@@ -113,6 +113,7 @@ class WasmSymbols(
     val booleanAnd = getInternalFunction("wasm_i32_and")
     val refEq = getInternalFunction("wasm_ref_eq")
     val refIsNull = getInternalFunction("wasm_ref_is_null")
+    val refTest = getInternalFunction("wasm_ref_test")
     val intToLong = getInternalFunction("wasm_i64_extend_i32_s")
 
     val wasmRefCast = getInternalFunction("wasm_ref_cast")

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/BodyGenerator.kt

@@ -258,7 +258,7 @@ class BodyGenerator(val context: WasmFunctionCodegenContext) : IrElementVisitorV
         call: IrFunctionAccessExpression,
         function: IrFunction
     ): Boolean {
-        if (tryToGenerateWasmOpIntrinsicCall(function)) {
+        if (tryToGenerateWasmOpIntrinsicCall(call, function)) {
             return true
         }
 
@@ -489,7 +489,7 @@ class BodyGenerator(val context: WasmFunctionCodegenContext) : IrElementVisitorV
     }
 
     // Return true if function is recognized as intrinsic.
-    fun tryToGenerateWasmOpIntrinsicCall(function: IrFunction): Boolean {
+    fun tryToGenerateWasmOpIntrinsicCall(call: IrFunctionAccessExpression, function: IrFunction): Boolean {
         if (function.hasWasmReinterpretAnnotation()) {
             return true
         }
@@ -513,6 +513,25 @@ class BodyGenerator(val context: WasmFunctionCodegenContext) : IrElementVisitorV
                         }
                     )
                 }
+                2 -> {
+                    when (op) {
+                        WasmOp.REF_TEST -> {
+                            val fromIrType = call.getValueArgument(0)!!.type
+                            val fromWasmType = context.transformBoxedType(fromIrType)
+                            val toIrType = call.getTypeArgument(0)!!
+                            val toWasmType = context.transformBoxedType(toIrType)
+                            immediates = arrayOf(
+                                WasmImmediate.HeapType(fromWasmType),
+                                WasmImmediate.HeapType(toWasmType),
+                            )
+
+                            // ref.test takes RTT as a second operand
+                            generateTypeRTT(toIrType)
+                        }
+                        else ->
+                            error("Op $opString is unsupported")
+                    }
+                }
                 else ->
                     error("Op $opString is unsupported")
             }

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmTypeOperatorLowering.kt

@@ -13,7 +13,6 @@ import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.irNot
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.erasedUpperBound
-import org.jetbrains.kotlin.ir.util.isPure
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.declarations.IrTypeParameter
@@ -276,12 +275,25 @@ class WasmBaseTypeOperatorTransformer(val context: WasmBackendContext) : IrEleme
     }
 
     private fun generateIsSubClass(argument: IrExpression, toType: IrType): IrExpression {
-        val classId = builder.irCall(symbols.wasmClassId).apply {
-            putTypeArgument(0, toType)
+        val fromType = argument.type
+        val fromTypeErased = fromType.erasedType
+        val toTypeErased = toType.erasedType
+        if (fromTypeErased.isSubtypeOfClass(toTypeErased.classOrNull!!)) {
+            return builder.irComposite {
+                +argument
+                +builder.irTrue()
+            }
         }
-        return builder.irCall(symbols.isSubClass).apply {
+        if (!toTypeErased.isSubtypeOfClass(fromTypeErased.classOrNull!!)) {
+            return builder.irComposite {
+                +argument
+                +builder.irFalse()
+            }
+        }
+
+        return builder.irCall(symbols.refTest).apply {
             putValueArgument(0, argument)
-            putValueArgument(1, classId)
+            putTypeArgument(0, toType)
         }
     }
 }

libraries/stdlib/wasm/internal/kotlin/wasm/internal/WasmInstructions.kt

@@ -254,6 +254,8 @@ public external fun wasm_ref_is_null(a: Any?): Boolean
 @WasmOp(WasmOp.REF_EQ)
 public external fun wasm_ref_eq(a: Any?, b: Any?): Boolean
 
+@WasmOp(WasmOp.REF_TEST)
+public external fun <T> wasm_ref_test(a: Any?): Boolean
 
 // ---