Remove all uses of get_flip and deprecate

It is O(n) and every use is in an O(n) iteration resulting in O(n^2).
Same information can be extracted from create_exps which happens to also
be called at every use of get_flip.

4 files changed, 10 insertions, 10 deletions

diff --git a/src/main/scala/firrtl/Utils.scala b/src/main/scala/firrtl/Utils.scala
index 53e8c157..44b16bf8 100644
--- a/src/main/scala/firrtl/Utils.scala
+++ b/src/main/scala/firrtl/Utils.scala
@@ -300,6 +300,7 @@ object Utils extends LazyLogging {
     onExp(expression)
     ReferenceTarget(main, module, Nil, ref, tokens)
   }
+   @deprecated("get_flip is fundamentally slow, use to_flip(gender(expr))", "1.2")
    def get_flip(t: Type, i: Int, f: Orientation): Orientation = {
      if (i >= get_size(t)) throwInternalError(s"get_flip: shouldn't be here - $i >= get_size($t)")
      t match {
diff --git a/src/main/scala/firrtl/passes/ExpandWhens.scala b/src/main/scala/firrtl/passes/ExpandWhens.scala
index 964b8494..9136c913 100644
--- a/src/main/scala/firrtl/passes/ExpandWhens.scala
+++ b/src/main/scala/firrtl/passes/ExpandWhens.scala
@@ -204,12 +204,11 @@ object ExpandWhens extends Pass {
 
   /** Returns all references to all Female leaf subcomponents of a reference */
   private def getFemaleRefs(n: String, t: Type, g: Gender): Seq[Expression] = {
-    def getGender(t: Type, i: Int, g: Gender): Gender = times(g, get_flip(t, i, Default))
     val exps = create_exps(WRef(n, t, ExpKind, g))
-    exps.zipWithIndex.flatMap { case (exp, j) =>
+    exps.flatMap { case exp =>
       exp.tpe match {
         case AnalogType(w) => None
-        case _ => getGender(t, j, g) match {
+        case _ => gender(exp) match {
           case (BIGENDER | FEMALE) => Some(exp)
           case _ => None
         }
diff --git a/src/main/scala/firrtl/passes/InferWidths.scala b/src/main/scala/firrtl/passes/InferWidths.scala
index 1e9532c8..26d346bb 100644
--- a/src/main/scala/firrtl/passes/InferWidths.scala
+++ b/src/main/scala/firrtl/passes/InferWidths.scala
@@ -263,12 +263,12 @@ object InferWidths extends Pass {
           val n = get_size(s.loc.tpe)
           val locs = create_exps(s.loc)
           val exps = create_exps(s.expr)
-          v ++= ((locs zip exps).zipWithIndex flatMap {case ((locx, expx), i) =>
-            get_flip(s.loc.tpe, i, Default) match {
+          v ++= locs.zip(exps).flatMap { case (locx, expx) =>
+            to_flip(gender(locx)) match {
               case Default => get_constraints_t(locx.tpe, expx.tpe)//WGeq(getWidth(locx), getWidth(expx))
               case Flip => get_constraints_t(expx.tpe, locx.tpe)//WGeq(getWidth(expx), getWidth(locx))
             }
-          })
+          }
         case (s: PartialConnect) =>
           val ls = get_valid_points(s.loc.tpe, s.expr.tpe, Default, Default)
           val locs = create_exps(s.loc)
@@ -276,7 +276,7 @@ object InferWidths extends Pass {
           v ++= (ls flatMap {case (x, y) =>
             val locx = locs(x)
             val expx = exps(y)
-            get_flip(s.loc.tpe, x, Default) match {
+            to_flip(gender(locx)) match {
               case Default => get_constraints_t(locx.tpe, expx.tpe)//WGeq(getWidth(locx), getWidth(expx))
               case Flip => get_constraints_t(expx.tpe, locx.tpe)//WGeq(getWidth(expx), getWidth(locx))
             }
diff --git a/src/main/scala/firrtl/passes/Passes.scala b/src/main/scala/firrtl/passes/Passes.scala
index 45413348..bb65201b 100644
--- a/src/main/scala/firrtl/passes/Passes.scala
+++ b/src/main/scala/firrtl/passes/Passes.scala
@@ -140,8 +140,8 @@ object ExpandConnects extends Pass {
           case sx: Connect =>
             val locs = create_exps(sx.loc)
             val exps = create_exps(sx.expr)
-            Block((locs zip exps).zipWithIndex map {case ((locx, expx), i) =>
-               get_flip(sx.loc.tpe, i, Default) match {
+            Block(locs.zip(exps).map { case (locx, expx) =>
+               to_flip(gender(locx)) match {
                   case Default => Connect(sx.info, locx, expx)
                   case Flip => Connect(sx.info, expx, locx)
                }
@@ -154,7 +154,7 @@ object ExpandConnects extends Pass {
               locs(x).tpe match {
                 case AnalogType(_) => Attach(sx.info, Seq(locs(x), exps(y)))
                 case _ =>
-                  get_flip(sx.loc.tpe, x, Default) match {
+                  to_flip(gender(locs(x))) match {
                     case Default => Connect(sx.info, locs(x), exps(y))
                     case Flip => Connect(sx.info, exps(y), locs(x))
                   }