refactor: extract Stack, proper register naming and sizes

src/main/wacc/backend/sizeExtensions.scala

@@ -0,0 +1,29 @@
+package wacc
+
+object sizeExtensions {
+  import microWacc._
+  import types._
+  import assemblyIR.Size
+
+  extension (expr: Expr) {
+
+    /** Calculate the size (bytes) of the heap required for the expression. */
+    def heapSize: Int = (expr, expr.ty) match {
+      case (ArrayLiter(elems), KnownType.Array(KnownType.Char)) =>
+        KnownType.Int.size.toInt + elems.size.toInt * KnownType.Char.size.toInt
+      case (ArrayLiter(elems), _) =>
+        KnownType.Int.size.toInt + elems.map(_.ty.size.toInt).sum
+      case _ => expr.ty.size.toInt
+    }
+  }
+
+  extension (ty: SemType) {
+
+    /** Calculate the size (bytes) of a type in a register. */
+    def size: Size = ty match {
+      case KnownType.Int                                                    => Size.D32
+      case KnownType.Bool | KnownType.Char                                  => Size.B8
+      case KnownType.String | KnownType.Array(_) | KnownType.Pair(_, _) | ? => Size.Q64
+    }
+  }
+}