Dedup attribute annos (#2297)

* Add new util "groupByIntoSeq"
* Restore annotation order when dedupping annotations
* Attribute annotations now deduplicate
* Implement doc string anno dedup

Co-authored-by: Jack Koenig <koenig@sifive.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/Utils.scala b/src/main/scala/firrtl/Utils.scala
index e29c1a3b..e2bb06ff 100644
--- a/src/main/scala/firrtl/Utils.scala
+++ b/src/main/scala/firrtl/Utils.scala
@@ -967,6 +967,17 @@ object Utils extends LazyLogging {
     Mux(cond, tval, fval, tval.tpe)
   }
 
+  /** Similar to Seq.groupBy except that it preserves ordering of elements within each group */
+  def groupByIntoSeq[A, K](xs: Iterable[A])(f: A => K): Seq[(K, Seq[A])] = {
+    val map = mutable.LinkedHashMap.empty[K, mutable.ListBuffer[A]]
+    for (x <- xs) {
+      val key = f(x)
+      val l = map.getOrElseUpdate(key, mutable.ListBuffer.empty[A])
+      l += x
+    }
+    map.view.map({ case (k, vs) => k -> vs.toList }).toList
+  }
+
   object True {
     private val _True = UIntLiteral(1, IntWidth(1))