Add counter for depth of when scope

3 files changed, 18 insertions, 1 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Module.scala b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
index de13c078..3ff68772 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Module.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Module.scala
@@ -31,16 +31,25 @@ object Module {
     }
     Builder.readyForModuleConstr = true
     val parent: Option[Module] = Builder.currentModule
+    val whenDepth: Int = Builder.whenDepth
 
-    val m = bc.setRefs() // This will set currentModule and unset readyForModuleConstr!!!
+    // Execute the module, this has the following side effects:
+    //   - set currentModule
+    //   - unset readyForModuleConstr
+    //   - reset whenDepth to 0
+    val m = bc.setRefs()
     m._commands.prepend(DefInvalid(childSourceInfo, m.io.ref)) // init module outputs
 
+    if (Builder.whenDepth != 0) {
+      throwException("Internal Error! When depth is != 0, this should not be possible")
+    }
     if (Builder.readyForModuleConstr) {
       throwException("Error: attempted to instantiate a Module, but nothing happened. " +
                      "This is probably due to rewrapping a Module instance with Module()." +
                      sourceInfo.makeMessage(" See " + _))
     }
     Builder.currentModule = parent // Back to parent!
+    Builder.whenDepth = whenDepth
 
     val ports = m.computePorts
     // Blackbox inherits from Module so we have to match on it first TODO fix
@@ -118,6 +127,7 @@ extends HasId {
   private[chisel3] val _commands = ArrayBuffer[Command]()
   private[core] val _ids = ArrayBuffer[HasId]()
   Builder.currentModule = Some(this)
+  Builder.whenDepth = 0
   if (!Builder.readyForModuleConstr) {
     throwException("Error: attempted to instantiate a Module without wrapping it in Module().")
   }
diff --git a/chiselFrontend/src/main/scala/chisel3/core/When.scala b/chiselFrontend/src/main/scala/chisel3/core/When.scala
index 7501ebb1..9b646855 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/When.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/When.scala
@@ -54,6 +54,8 @@ final class WhenContext(sourceInfo: SourceInfo, cond: Bool, prevCond: => Bool, b
     new WhenContext(sourceInfo, prevCond, null, block)
 
   pushCommand(WhenBegin(sourceInfo, cond.ref))
+  Builder.whenDepth += 1
   block
+  Builder.whenDepth -= 1
   pushCommand(WhenEnd(sourceInfo))
 }
diff --git a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
index d8202da6..9e389788 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
@@ -150,6 +150,7 @@ private[chisel3] class DynamicContext() {
   // Set by object Module.apply before calling class Module constructor
   // Used to distinguish between no Module() wrapping, multiple wrappings, and rewrapping
   var readyForModuleConstr: Boolean = false
+  var whenDepth: Int = 0 // Depth of when nesting
   val errors = new ErrorLog
   val namingStack = new internal.naming.NamingStack
 }
@@ -181,6 +182,10 @@ private[chisel3] object Builder {
   def readyForModuleConstr_=(target: Boolean): Unit = {
     dynamicContext.readyForModuleConstr = target
   }
+  def whenDepth: Int = dynamicContext.whenDepth
+  def whenDepth_=(target: Int): Unit = {
+    dynamicContext.whenDepth = target
+  }
 
   // TODO(twigg): Ideally, binding checks and new bindings would all occur here
   // However, rest of frontend can't support this yet.