Improve performance of LowerTypes renaming (#2024)

This is done by having LowerTypes uses two RenameMaps instead of one for
each module. There is one for renaming instance paths, and one for
renaming everything within modules.

Also add some utilities:
* TargetUtils for dealing with InstanceTargets
* RenameMap.fromInstanceRenames

2 files changed, 58 insertions, 0 deletions

diff --git a/src/test/scala/firrtlTests/RenameMapSpec.scala b/src/test/scala/firrtlTests/RenameMapSpec.scala
index 29466c72..bebeb0bf 100644
--- a/src/test/scala/firrtlTests/RenameMapSpec.scala
+++ b/src/test/scala/firrtlTests/RenameMapSpec.scala
@@ -5,6 +5,8 @@ package firrtlTests
 import firrtl.RenameMap
 import firrtl.RenameMap.IllegalRenameException
 import firrtl.annotations._
+import firrtl.annotations.TargetToken.{Instance, OfModule}
+import firrtl.analyses.InstanceKeyGraph
 import firrtl.testutils._
 
 class RenameMapSpec extends FirrtlFlatSpec {
diff --git a/src/test/scala/firrtlTests/annotationTests/TargetUtilsSpec.scala b/src/test/scala/firrtlTests/annotationTests/TargetUtilsSpec.scala
new file mode 100644
index 00000000..38266efe
--- /dev/null
+++ b/src/test/scala/firrtlTests/annotationTests/TargetUtilsSpec.scala
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package firrtlTests.annotationTests
+
+import firrtl.analyses.InstanceKeyGraph.InstanceKey
+import firrtl.annotations._
+import firrtl.annotations.TargetToken._
+import firrtl.annotations.TargetUtils._
+import firrtl.testutils.FirrtlFlatSpec
+
+class TargetUtilsSpec extends FirrtlFlatSpec {
+
+  behavior.of("instKeyPathToTarget")
+
+  it should "create a ModuleTarget for the top module" in {
+    val input = InstanceKey("Top", "Top") :: Nil
+    val expected = ModuleTarget("Top", "Top")
+    instKeyPathToTarget(input) should be(expected)
+  }
+
+  it should "create absolute InstanceTargets" in {
+    val input = InstanceKey("Top", "Top") ::
+      InstanceKey("foo", "Foo") ::
+      InstanceKey("bar", "Bar") ::
+      Nil
+    val expected = InstanceTarget("Top", "Top", Seq((Instance("foo"), OfModule("Foo"))), "bar", "Bar")
+    instKeyPathToTarget(input) should be(expected)
+  }
+
+  it should "support starting somewhere down the path" in {
+    val input = InstanceKey("Top", "Top") ::
+      InstanceKey("foo", "Foo") ::
+      InstanceKey("bar", "Bar") ::
+      InstanceKey("fizz", "Fizz") ::
+      Nil
+    val expected = InstanceTarget("Top", "Bar", Seq(), "fizz", "Fizz")
+    instKeyPathToTarget(input, Some("Bar")) should be(expected)
+  }
+
+  behavior.of("unfoldInstanceTargets")
+
+  it should "return nothing for ModuleTargets" in {
+    val input = ModuleTarget("Top", "Foo")
+    unfoldInstanceTargets(input) should be(Iterable())
+  }
+
+  it should "return all other InstanceTargets to the same instance" in {
+    val input = ModuleTarget("Top", "Top").instOf("foo", "Foo").instOf("bar", "Bar").instOf("fizz", "Fizz")
+    val expected =
+      input ::
+        ModuleTarget("Top", "Foo").instOf("bar", "Bar").instOf("fizz", "Fizz") ::
+        ModuleTarget("Top", "Bar").instOf("fizz", "Fizz") ::
+        Nil
+    unfoldInstanceTargets(input) should be(expected)
+  }
+}