backend: connect lowering with IR generators

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/common/BackendContext.kt

@@ -18,8 +18,10 @@ package org.jetbrains.kotlin.backend.common
 
 import org.jetbrains.kotlin.backend.common.descriptors.SharedVariablesManager
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 
 interface BackendContext {
     val builtIns: KotlinBuiltIns
+    val irBuiltIns: IrBuiltIns
     val sharedVariablesManager: SharedVariablesManager
 }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/common/lower/LowerUtils.kt

@@ -0,0 +1,39 @@
+package org.jetbrains.kotlin.backend.common.lower
+
+import org.jetbrains.kotlin.backend.common.BackendContext
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
+import org.jetbrains.kotlin.ir.builders.*
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.IrStatementOrigin
+import org.jetbrains.kotlin.types.KotlinType
+
+class IrLoweringContext(backendContext: BackendContext) : GeneratorContext {
+    override val irBuiltIns: IrBuiltIns = backendContext.irBuiltIns
+}
+
+class FunctionIrGenerator(backendContext: BackendContext, functionDescriptor: FunctionDescriptor) : GeneratorWithScope {
+    override val context = IrLoweringContext(backendContext)
+    override val scope = Scope(functionDescriptor)
+}
+
+fun BackendContext.createFunctionIrGenerator(functionDescriptor: FunctionDescriptor) =
+        FunctionIrGenerator(this, functionDescriptor)
+
+class FunctionIrBuilder(context: IrLoweringContext, scope: Scope, startOffset: Int, endOffset: Int) :
+        IrBuilderWithScope(context, scope, startOffset, endOffset)
+
+fun FunctionIrGenerator.createIrBuilder() = FunctionIrBuilder(context, scope, UNDEFINED_OFFSET, UNDEFINED_OFFSET)
+
+/**
+ * Builds [IrBlock] to be used instead of given expression.
+ */
+inline fun FunctionIrGenerator.irBlock(expression: IrExpression, origin: IrStatementOrigin? = null,
+                                       resultType: KotlinType? = expression.type,
+                                       body: IrBlockBuilder.() -> Unit) =
+        this.irBlock(expression.startOffset, expression.endOffset, origin, resultType, body)
+
+inline fun FunctionIrGenerator.irBlockBody(irElement: IrElement, body: IrBlockBodyBuilder.() -> Unit) =
+        this.irBlockBody(irElement.startOffset, irElement.endOffset, body)

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

@@ -37,6 +37,9 @@ internal final class Context(val config: KonanConfig,
 
     lateinit var ir: Ir
 
+    override val irBuiltIns
+        get() = ir.irModule.irBuiltins
+
     var llvmModule: LLVMModuleRef? = null
         set(module: LLVMModuleRef?) {
             if (field != null) {

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

@@ -4,7 +4,7 @@ import org.jetbrains.kotlin.backend.common.BackendContext
 import org.jetbrains.kotlin.backend.konan.descriptors.KonanSharedVariablesManager
 import org.jetbrains.kotlin.backend.konan.KonanPlatform
 
-open internal class KonanBackendContext : BackendContext {
+abstract internal class KonanBackendContext : BackendContext {
     override val builtIns = KonanPlatform.builtIns
 
     override val sharedVariablesManager by lazy {