Batch renames in LowerTypes (#1718)

* Batch renames in LowerTypes

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

* Add benchmarking for LowerTypes

Add infrastructure of benchmarking Transforms (in addition to
existing infra for Passes). Also run System.gc between each timed
benchmark to improve stability.

Co-authored-by: Jack Koenig <koenig@sifive.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

3 files changed, 37 insertions, 8 deletions

diff --git a/benchmark/src/main/scala/firrtl/benchmark/hot/TransformBenchmark.scala b/benchmark/src/main/scala/firrtl/benchmark/hot/TransformBenchmark.scala
new file mode 100644
index 00000000..05b759c6
--- /dev/null
+++ b/benchmark/src/main/scala/firrtl/benchmark/hot/TransformBenchmark.scala
@@ -0,0 +1,27 @@
+// See LICENSE for license details.
+
+package firrtl
+package benchmark
+package hot
+
+import firrtl._
+import firrtl.passes.LowerTypes
+import firrtl.stage.TransformManager
+
+import firrtl.benchmark.util._
+
+abstract class TransformBenchmark(factory: () => Transform) extends App {
+  val inputFile = args(0)
+  val warmup = args(1).toInt
+  val runs = args(2).toInt
+
+  val input = filenameToCircuit(inputFile)
+  val inputState = CircuitState(input, ChirrtlForm)
+
+  val manager = new TransformManager(factory().prerequisites)
+  val preState = manager.execute(inputState)
+
+  hot.util.benchmark(warmup, runs)(factory().transform(preState))
+}
+
+object LowerTypesBenchmark extends TransformBenchmark(() => LowerTypes)
diff --git a/benchmark/src/main/scala/firrtl/benchmark/hot/util/package.scala b/benchmark/src/main/scala/firrtl/benchmark/hot/util/package.scala
index c05b8359..911bd03a 100644
--- a/benchmark/src/main/scala/firrtl/benchmark/hot/util/package.scala
+++ b/benchmark/src/main/scala/firrtl/benchmark/hot/util/package.scala
@@ -15,6 +15,7 @@ package object util {
     // Benchmark
     val times: Array[Double] = Array.fill(nRun)(0.0)
     for (i <- 0 until nRun) {
+      System.gc
       val (t, res) = time(f)
       times(i) = t
       println(f"Benchmark run $i took $t%.1f ms")
diff --git a/src/main/scala/firrtl/passes/LowerTypes.scala b/src/main/scala/firrtl/passes/LowerTypes.scala
index ccfe5828..29792d17 100644
--- a/src/main/scala/firrtl/passes/LowerTypes.scala
+++ b/src/main/scala/firrtl/passes/LowerTypes.scala
@@ -55,16 +55,16 @@ object LowerTypes extends Transform with DependencyAPIMigration {
       val name = root + loweredName(e)
       renames.rename(root + e.serialize, name)
       Seq(name)
-    case (t: BundleType) => t.fields.flatMap { f =>
-      val subNames = renameExps(renames, WSubField(e, f.name, f.tpe, times(flow(e), f.flip)), root)
+    case (t: BundleType) =>
+      val subNames = t.fields.flatMap { f =>
+        renameExps(renames, WSubField(e, f.name, f.tpe, times(flow(e), f.flip)), root)
+      }
       renames.rename(root + e.serialize, subNames)
       subNames
-    }
-    case (t: VectorType) => (0 until t.size).flatMap { i =>
-      val subNames = renameExps(renames, WSubIndex(e, i, t.tpe,flow(e)), root)
+    case (t: VectorType) =>
+      val subNames = (0 until t.size).flatMap { i => renameExps(renames, WSubIndex(e, i, t.tpe,flow(e)), root) }
       renames.rename(root + e.serialize, subNames)
       subNames
-    }
   }
 
   private def renameMemExps(renames: RenameMap, e: Expression, portAndField: Expression): Seq[String] = e.tpe match {
@@ -224,9 +224,10 @@ object LowerTypes extends Transform with DependencyAPIMigration {
                 val d = WRef(mem.name, sx.dataType)
                 tail match {
                   case None =>
-                    create_exps(mem.name, sx.dataType) foreach { x =>
-                      renames.rename(e.serialize, s"${loweredName(x)}.${port.serialize}.${field.serialize}")
+                    val names = create_exps(mem.name, sx.dataType).map { x =>
+                      s"${loweredName(x)}.${port.serialize}.${field.serialize}"
                     }
+                    renames.rename(e.serialize, names)
                   case Some(_) =>
                     renameMemExps(renames, d, mergeRef(port, field))
                 }