1 files changed, 25 insertions, 24 deletions

diff --git a/core/src/main/scala/chisel3/internal/Builder.scala b/core/src/main/scala/chisel3/internal/Builder.scala
index 1ffe54ab..4180f580 100644
--- a/core/src/main/scala/chisel3/internal/Builder.scala
+++ b/core/src/main/scala/chisel3/internal/Builder.scala
@@ -35,7 +35,7 @@ private[chisel3] class Namespace(keywords: Set[String]) {
     // TODO what character set does FIRRTL truly support? using ANSI C for now
     def legalStart(c: Char) = (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_'
     def legal(c:      Char) = legalStart(c) || (c >= '0' && c <= '9')
-    val res = s.filter(legal)
+    val res = if (s.forall(legal)) s else s.filter(legal)
     val headOk = (!res.isEmpty) && (leadingDigitOk || legalStart(res.head))
     if (headOk) res else s"_$res"
   }
@@ -45,12 +45,9 @@ private[chisel3] class Namespace(keywords: Set[String]) {
   // leadingDigitOk is for use in fields of Records
   def name(elem: String, leadingDigitOk: Boolean = false): String = {
     val sanitized = sanitize(elem, leadingDigitOk)
-    if (this contains sanitized) {
-      name(rename(sanitized))
-    } else {
-      names(sanitized) = 1
-      sanitized
-    }
+    val result = if (this.contains(sanitized)) rename(sanitized) else sanitized
+    names(result) = 1
+    result
   }
 }
 
@@ -108,17 +105,16 @@ private[chisel3] trait HasId extends InstanceId {
   // Contains the seed computed automatically by the compiler plugin
   private var auto_seed: Option[String] = None
 
-  // Prefix at time when this class is constructed
-  private val construction_prefix: Prefix = Builder.getPrefix
-
-  // Prefix when the latest [[suggestSeed]] or [[autoSeed]] is called
-  private var prefix_seed: Prefix = Nil
+  // Prefix for use in naming
+  // - Defaults to prefix at time when object is created
+  // - Overridden when [[suggestSeed]] or [[autoSeed]] is called
+  private var naming_prefix: Prefix = Builder.getPrefix
 
   // Post-seed hooks called to carry the suggested seeds to other candidates as needed
-  private val suggest_postseed_hooks = scala.collection.mutable.ListBuffer.empty[String => Unit]
+  private var suggest_postseed_hooks: List[String => Unit] = Nil
 
   // Post-seed hooks called to carry the auto seeds to other candidates as needed
-  private val auto_postseed_hooks = scala.collection.mutable.ListBuffer.empty[String => Unit]
+  private var auto_postseed_hooks: List[String => Unit] = Nil
 
   /** Takes the last seed suggested. Multiple calls to this function will take the last given seed, unless
     * this HasId is a module port (see overridden method in Data.scala).
@@ -136,8 +132,8 @@ private[chisel3] trait HasId extends InstanceId {
   // Bypass the overridden behavior of autoSeed in [[Data]], apply autoSeed even to ports
   private[chisel3] def forceAutoSeed(seed: String): this.type = {
     auto_seed = Some(seed)
-    for (hook <- auto_postseed_hooks) { hook(seed) }
-    prefix_seed = Builder.getPrefix
+    for (hook <- auto_postseed_hooks.reverse) { hook(seed) }
+    naming_prefix = Builder.getPrefix
     this
   }
 
@@ -153,8 +149,8 @@ private[chisel3] trait HasId extends InstanceId {
     */
   def suggestName(seed: => String): this.type = {
     if (suggested_seed.isEmpty) suggested_seed = Some(seed)
-    prefix_seed = Builder.getPrefix
-    for (hook <- suggest_postseed_hooks) { hook(seed) }
+    naming_prefix = Builder.getPrefix
+    for (hook <- suggest_postseed_hooks.reverse) { hook(seed) }
     this
   }
 
@@ -183,18 +179,21 @@ private[chisel3] trait HasId extends InstanceId {
       */
     def buildName(seed: String, prefix: Prefix): String = {
       val builder = new StringBuilder()
-      prefix.foreach(builder ++= _ + "_")
+      prefix.foreach { p =>
+        builder ++= p
+        builder += '_'
+      }
       builder ++= seed
       builder.toString
     }
 
     if (hasSeed) {
-      Some(buildName(seedOpt.get, prefix_seed.reverse))
+      Some(buildName(seedOpt.get, naming_prefix.reverse))
     } else {
       defaultSeed.map { default =>
         defaultPrefix match {
-          case Some(p) => buildName(default, p :: construction_prefix.reverse)
-          case None    => buildName(default, construction_prefix.reverse)
+          case Some(p) => buildName(default, p :: naming_prefix.reverse)
+          case None    => buildName(default, naming_prefix.reverse)
         }
       }
     }
@@ -211,8 +210,8 @@ private[chisel3] trait HasId extends InstanceId {
 
   private[chisel3] def hasAutoSeed: Boolean = auto_seed.isDefined
 
-  private[chisel3] def addSuggestPostnameHook(hook: String => Unit): Unit = suggest_postseed_hooks += hook
-  private[chisel3] def addAutoPostnameHook(hook:    String => Unit): Unit = auto_postseed_hooks += hook
+  private[chisel3] def addSuggestPostnameHook(hook: String => Unit): Unit = suggest_postseed_hooks ::= hook
+  private[chisel3] def addAutoPostnameHook(hook:    String => Unit): Unit = auto_postseed_hooks ::= hook
 
   // Uses a namespace to convert suggestion into a true name
   // Will not do any naming if the reference already assigned.
@@ -222,6 +221,8 @@ private[chisel3] trait HasId extends InstanceId {
       val candidate_name = _computeName(prefix, Some(default)).get
       val available_name = namespace.name(candidate_name)
       setRef(Ref(available_name))
+      // Clear naming prefix to free memory
+      naming_prefix = Nil
     }
 
   private var _ref: Option[Arg] = None