From 2416d1d44a2bd73bd0556437ece7a7a24d649a7a Mon Sep 17 00:00:00 2001
From: Schuyler Eldridge
Date: Thu, 25 Oct 2018 13:37:00 -0400
Subject: Make BaseModule.name lazy

This changes BaseModule.name to be lazy (instead of eager) to enable a
desiredName to be a function of a sub-instance. This includes a test case
showing the new behavior.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>
---
 chiselFrontend/src/main/scala/chisel3/core/Module.scala | 2 +-
 src/test/scala/chiselTests/Module.scala                 | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Module.scala b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
index 88013bae..89dd2dee 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Module.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
@@ -180,7 +180,7 @@ abstract class BaseModule extends HasId {
   def desiredName = this.getClass.getName.split('.').last
 
   /** Legalized name of this module. */
-  final val name = Builder.globalNamespace.name(desiredName)
+  final lazy val name = Builder.globalNamespace.name(desiredName)
 
   /** Returns a FIRRTL ModuleName that references this object
     * @note Should not be called until circuit elaboration is complete
diff --git a/src/test/scala/chiselTests/Module.scala b/src/test/scala/chiselTests/Module.scala
index 968e7578..dc44838a 100644
--- a/src/test/scala/chiselTests/Module.scala
+++ b/src/test/scala/chiselTests/Module.scala
@@ -62,6 +62,12 @@ class ModuleRewrap extends Module {
   val inst2 = Module(inst)
 }
 
+class ModuleWrapper(gen: => Module) extends Module {
+  val io = IO(new Bundle{})
+  val child = Module(gen)
+  override lazy val desiredName = s"${child.desiredName}Wrapper"
+}
+
 class ModuleSpec extends ChiselPropSpec {
 
   property("ModuleVec should elaborate") {
@@ -138,4 +144,7 @@ class ModuleSpec extends ChiselPropSpec {
           "a" -> m.a, "b" -> m.b))
     })
   }
+  property("A desiredName parameterized by a submodule should work") {
+    Driver.elaborate(() => new ModuleWrapper(new ModuleWire)).name should be ("ModuleWireWrapper")
+  }
 }
-- 
cgit v1.2.3


From f64388e7cfe71004df93ddeef88447978f37ecb1 Mon Sep 17 00:00:00 2001
From: Schuyler Eldridge
Date: Thu, 25 Oct 2018 16:27:49 -0400
Subject: Check BaseModule.name for NullPointerException

This wraps the evaluation of BaseModule.name in try/catch to look for a
NullPointerException that may result from trying to evaluate desiredName
before it's ready. This catches a test case of using a desiredName that
depends on a later defined eager subinstance.

h/t @jackkoenig

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>
---
 chiselFrontend/src/main/scala/chisel3/core/Module.scala |  8 +++++++-
 src/test/scala/chiselTests/Module.scala                 | 11 +++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Module.scala b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
index 89dd2dee..3bdc86d6 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Module.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
@@ -180,7 +180,13 @@ abstract class BaseModule extends HasId {
   def desiredName = this.getClass.getName.split('.').last
 
   /** Legalized name of this module. */
-  final lazy val name = Builder.globalNamespace.name(desiredName)
+  final lazy val name = try {
+    Builder.globalNamespace.name(desiredName)
+  } catch {
+    case e: NullPointerException => throwException(
+      s"Error: desiredName of ${this.getClass.getName} is null. Did you evaluate 'name' before all values needed by desiredName were available?", e)
+    case t: Throwable => throw t
+  }
 
   /** Returns a FIRRTL ModuleName that references this object
     * @note Should not be called until circuit elaboration is complete
diff --git a/src/test/scala/chiselTests/Module.scala b/src/test/scala/chiselTests/Module.scala
index dc44838a..b3d1899c 100644
--- a/src/test/scala/chiselTests/Module.scala
+++ b/src/test/scala/chiselTests/Module.scala
@@ -65,7 +65,14 @@ class ModuleRewrap extends Module {
 class ModuleWrapper(gen: => Module) extends Module {
   val io = IO(new Bundle{})
   val child = Module(gen)
+  override val desiredName = s"${child.desiredName}Wrapper"
+}
+
+class NullModuleWrapper extends Module {
+  val io = IO(new Bundle{})
   override lazy val desiredName = s"${child.desiredName}Wrapper"
+  println(s"My name is ${name}")
+  val child = Module(new ModuleWire)
 }
 
 class ModuleSpec extends ChiselPropSpec {
@@ -147,4 +154,8 @@ class ModuleSpec extends ChiselPropSpec {
   property("A desiredName parameterized by a submodule should work") {
     Driver.elaborate(() => new ModuleWrapper(new ModuleWire)).name should be ("ModuleWireWrapper")
   }
+  property("A name generating a null pointer exception should provide a good error message") {
+    (the [Exception] thrownBy (Driver.elaborate(() => new NullModuleWrapper)))
+      .getMessage should include ("desiredName of chiselTests.NullModuleWrapper is null")
+  }
 }
-- 
cgit v1.2.3