refactor: use LabelGenerator for RuntimeErrors

src/main/wacc/backend/LabelGenerator.scala

@@ -0,0 +1,46 @@
+package wacc
+
+import scala.collection.mutable
+import cats.data.Chain
+
+private class LabelGenerator {
+  import assemblyIR._
+  import microWacc.{CallTarget, Ident, Builtin}
+  import asmGenerator.escaped
+
+  private val strings = mutable.HashMap[String, String]()
+  private var labelVal = -1
+
+  /** Get an arbitrary label. */
+  def getLabel(): String = {
+    labelVal += 1
+    s".L$labelVal"
+  }
+
+  /** Get a named label for a function. */
+  def getLabel(target: CallTarget): String = target match {
+    case Ident(v, _)   => s"wacc_$v"
+    case Builtin(name) => s"_$name"
+  }
+
+  /** Get a named label for an error. */
+  def getLabel(target: RuntimeError): String =
+    s".L.${target.name}"
+
+  /** Get an arbitrary label for a string. */
+  def getLabel(str: String): String =
+    strings.getOrElseUpdate(str, s".L.str${strings.size}")
+
+  /** Get a named label for a string. */
+  def getLabel(src: String, name: String): String =
+    strings.getOrElseUpdate(src, s".L.$name.str${strings.size}")
+
+  /** Generate the assembly labels for constants that were labelled using the LabelGenerator. */
+  def generateConstants: Chain[AsmLine] =
+    strings.foldLeft(Chain.empty) { case (acc, (str, label)) =>
+      acc ++ Chain(
+        LabelDef(label),
+        Directive.Asciz(str.escaped)
+      )
+    }
+}