Micro-optimize Namespace.name (#2474) (#2475)

* During sanitize, only filter the String if needed
* Do not recurse on name, saving an unnecessary call to sanitize

(cherry picked from commit 559b3df3e5bd6c73588638aa44a6df1244a11a53)

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

1 files changed, 4 insertions, 7 deletions

diff --git a/core/src/main/scala/chisel3/internal/Builder.scala b/core/src/main/scala/chisel3/internal/Builder.scala
index 5d6dc7bc..c0007a5f 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
   }
 }