backend: support native interop value types

also improve reliability of `==` lowering

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

@@ -27,6 +27,8 @@ internal class InteropBuiltIns(builtIns: KonanBuiltIns) {
 
     val getPointerSize = packageScope.getContributedFunctions("getPointerSize").single()
 
+    val nullableInteropValueTypes = listOf(ValueType.C_POINTER, ValueType.NATIVE_POINTED)
+
     private val nativePtr = packageScope.getContributedClassifier(nativePtrName) as ClassDescriptor
 
     private val nativePointed = packageScope.getContributedClassifier(nativePointedName) as ClassDescriptor

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

@@ -24,7 +24,11 @@ enum class ValueType(val classFqName: FqNameUnsafe, val isNullable: Boolean = fa
     FLOAT(KotlinBuiltIns.FQ_NAMES._float),
     DOUBLE(KotlinBuiltIns.FQ_NAMES._double),
 
-    UNBOUND_CALLABLE_REFERENCE(FqNameUnsafe("konan.internal.UnboundCallableReference"))
+    UNBOUND_CALLABLE_REFERENCE(FqNameUnsafe("konan.internal.UnboundCallableReference")),
+    NATIVE_PTR(InteropBuiltIns.FqNames.nativePtr),
+
+    NATIVE_POINTED(InteropBuiltIns.FqNames.nativePointed, isNullable = true),
+    C_POINTER(InteropBuiltIns.FqNames.cPointer, isNullable = true)
 }
 
 private fun KotlinType.isConstructedFromGivenClass(fqName: FqNameUnsafe) =

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

@@ -65,6 +65,8 @@ internal fun IrMemberAccessExpression.addArguments(args: Map<ParameterDescriptor
 internal fun IrMemberAccessExpression.addArguments(args: List<Pair<ParameterDescriptor, IrExpression>>) =
         this.addArguments(args.toMap())
 
+internal fun IrExpression.isNullConst() = this is IrConst<*> && this.kind == IrConstKind.Null
+
 fun ir2string(ir: IrElement?): String = ir2stringWhole(ir).takeWhile { it != '\n' }
 
 fun ir2stringWhole(ir: IrElement?): String {

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/DataLayout.kt

@@ -15,7 +15,9 @@ private val valueTypes = ValueType.values().associate {
         ValueType.LONG -> LLVMInt64Type()
         ValueType.FLOAT -> LLVMFloatType()
         ValueType.DOUBLE -> LLVMDoubleType()
-        ValueType.UNBOUND_CALLABLE_REFERENCE -> int8TypePtr
+
+        ValueType.UNBOUND_CALLABLE_REFERENCE,
+        ValueType.NATIVE_PTR, ValueType.NATIVE_POINTED, ValueType.C_POINTER -> int8TypePtr
     }!!
 }
 

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/Autoboxing.kt

@@ -6,8 +6,10 @@ import org.jetbrains.kotlin.backend.konan.Context
 import org.jetbrains.kotlin.backend.konan.ValueType
 import org.jetbrains.kotlin.backend.konan.descriptors.getKonanInternalClass
 import org.jetbrains.kotlin.backend.konan.descriptors.getKonanInternalFunctions
+import org.jetbrains.kotlin.backend.konan.ir.isNullConst
 import org.jetbrains.kotlin.backend.konan.notNullableIsRepresentedAs
 import org.jetbrains.kotlin.backend.konan.isRepresentedAs
+import org.jetbrains.kotlin.backend.konan.util.atMostOne
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
@@ -103,6 +105,10 @@ private class AutoboxingTransformer(val context: Context) : AbstractValueUsageTr
     }
 
     override fun IrExpression.useAs(type: KotlinType): IrExpression {
+        val interop = context.interopBuiltIns
+        if (this.isNullConst() && interop.nullableInteropValueTypes.any { type.isRepresentedAs(it) }) {
+            return IrCallImpl(startOffset, endOffset, interop.getNativeNullPtr).uncheckedCast(type)
+        }
 
         val actualType = when (this) {
             is IrCall -> this.descriptor.original.returnType ?: this.type
@@ -176,6 +182,14 @@ private class AutoboxingTransformer(val context: Context) : AbstractValueUsageTr
     }
 
     private fun IrExpression.unbox(valueType: ValueType): IrExpression {
+        val unboxFunctionName = "unbox${valueType.shortName}"
+
+        context.builtIns.getKonanInternalFunctions(unboxFunctionName).atMostOne()?.let {
+            return IrCallImpl(startOffset, endOffset, it).apply {
+                putValueArgument(0, this@unbox.uncheckedCast(it.valueParameters[0].type))
+            }.uncheckedCast(this.type)
+        }
+
         val boxGetter = getBoxType(valueType)
                 .memberScope.getContributedDescriptors()
                 .filterIsInstance<PropertyDescriptor>()

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/BuiltinOperatorLowering.kt

@@ -3,6 +3,8 @@ package org.jetbrains.kotlin.backend.konan.lower
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.konan.Context
 import org.jetbrains.kotlin.backend.konan.descriptors.getKonanInternalFunctions
+import org.jetbrains.kotlin.backend.konan.ir.isNullConst
+import org.jetbrains.kotlin.backend.konan.util.atMostOne
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltinOperatorDescriptor
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.expressions.IrCall
@@ -69,9 +71,15 @@ private class BuiltinOperatorTransformer(val context: Context) : IrElementTransf
         // and thus can be declared synthetically in the compiler instead of explicitly in the runtime.
 
         // Find a type-compatible `konan.internal.areEqualByValue` intrinsic:
-        val equals = builtIns.getKonanInternalFunctions("areEqualByValue").firstOrNull {
+        val equals = builtIns.getKonanInternalFunctions("areEqualByValue").atMostOne {
             lhs.type.isSubtypeOf(it.valueParameters[0].type) && rhs.type.isSubtypeOf(it.valueParameters[1].type)
-        } ?: builtIns.getKonanInternalFunctions("areEqual").single() // or use the general implementation.
+        } ?: if (lhs.isNullConst() || rhs.isNullConst()) {
+            // or compare by reference if left or right part is `null`:
+            irBuiltins.eqeqeq
+        } else {
+            // or use the general implementation:
+            builtIns.getKonanInternalFunctions("areEqual").single()
+        }
 
         return IrCallImpl(startOffset, endOffset, equals).apply {
             putValueArgument(0, lhs)

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

@@ -20,3 +20,12 @@ fun nTabs(amount: Int): String {
     return String.format("%1$-${(amount+1)*4}s", "") 
 }
 
+fun <T> Collection<T>.atMostOne(): T? {
+    return when (this.size) {
+        0 -> null
+        1 -> this.iterator().next()
+        else -> throw IllegalArgumentException("Collection has more than one element.")
+    }
+}
+
+inline fun <T> Iterable<T>.atMostOne(predicate: (T) -> Boolean): T? = this.filter(predicate).atMostOne()