Flat codegen with infrastructure for adaptions.

wasm/src/main/scala/ir2wasm/TypeTransformer.scala

@@ -35,9 +35,8 @@ object TypeTransformer {
       t: IRTypes.Type
   )(implicit ctx: ReadOnlyWasmContext): List[Types.WasmType] =
     t match {
-      case IRTypes.NoType                                                      => Nil
-      case IRTypes.ClassType(className) if className == IRNames.BoxedUnitClass => Nil
-      case _ => List(transformType(t))
+      case IRTypes.NoType => Nil
+      case _              => List(transformType(t))
     }
   def transformType(t: IRTypes.Type)(implicit ctx: ReadOnlyWasmContext): Types.WasmType =
     t match {
@@ -64,6 +63,10 @@ object TypeTransformer {
             Types.WasmRefNullType(
               Types.WasmHeapType.Type(Names.WasmTypeName.WasmStructTypeName.string)
             )
+          case IRNames.BoxedUnitClass =>
+            Types.WasmRefNullType(
+              Types.WasmHeapType.Type(Names.WasmTypeName.WasmStructTypeName.undef)
+            )
           case _ =>
             if (ctx.getClassInfo(clazz.className).isInterface)
               Types.WasmRefNullType(Types.WasmHeapType.ObjectType)

wasm/src/main/scala/ir2wasm/WasmBuilder.scala

@@ -34,7 +34,6 @@ class WasmBuilder {
 
   def transformTopLevelExport(export: LinkedTopLevelExport)(implicit ctx: WasmContext): Unit = {
     implicit val fctx = WasmFunctionContext()
-    val expressionBuilder = new WasmExpressionBuilder(ctx, fctx)
     export.tree match {
       case d: IRTrees.TopLevelFieldExportDef   => ???
       case d: IRTrees.TopLevelJSClassExportDef => ???
@@ -295,7 +294,6 @@ class WasmBuilder {
   private def transformToplevelMethodExportDef(
       exportDef: IRTrees.TopLevelMethodExportDef
   )(implicit ctx: WasmContext, fctx: WasmFunctionContext) = {
-    val builder = new WasmExpressionBuilder(ctx, fctx)
     val method = exportDef.methodDef
     val methodName = method.name match {
       case lit: IRTrees.StringLiteral => lit
@@ -363,15 +361,12 @@ class WasmBuilder {
     }
     params.foreach(fctx.locals.define)
 
-    val instrs = newBody match {
-      case t: IRTrees.Block => t.stats.flatMap(builder.transformTree)
-      case _                => builder.transformTree(newBody)
-    }
+    val expr = WasmExpressionBuilder.transformBody(newBody, resultType)
     val func = WasmFunction(
       Names.WasmFunctionName(methodName),
       functionType,
       fctx.locals.all,
-      WasmExpr(instrs)
+      expr
     )
     ctx.addFunction(func)
 
@@ -417,18 +412,10 @@ class WasmBuilder {
     }).foreach(fctx.locals.define)
 
     // build function body
-    val builder = new WasmExpressionBuilder(ctx, fctx)
     val body = method.body.getOrElse(throw new Exception("abstract method cannot be transformed"))
     // val prefix =
     //   if (method.flags.namespace.isConstructor) builder.objectCreationPrefix(clazz, method) else Nil
-    val instrs = body match {
-      case t: IRTrees.Block => t.stats.flatMap(builder.transformTree)
-      case _                => builder.transformTree(body)
-    }
-    val expr = method.resultType match {
-      case IRTypes.NoType => WasmExpr(instrs)
-      case _              => WasmExpr(instrs :+ RETURN)
-    }
+    val expr = WasmExpressionBuilder.transformBody(body, method.resultType)
 
     val func = WasmFunction(
       Names.WasmFunctionName(clazz.name.name, method.name.name),