tilelink: don't pollute TLParamters with AtomicAutomata's implementation (#1111)

src/main/scala/tilelink/AtomicAutomata.scala

@@ -15,7 +15,6 @@ class TLAtomicAutomata(logical: Boolean = true, arithmetic: Boolean = true, conc
   require (concurrency >= 1)
 
   val node = TLAdapterNode(
-    clientFn  = { case cp => require (!cp.unsafeAtomics); cp.copy(unsafeAtomics = true) },
     managerFn = { case mp => mp.copy(managers = mp.managers.map { m =>
       val ourSupport = TransferSizes(1, mp.beatBytes)
       def widen(x: TransferSizes) = if (passthrough && x.min <= 2*mp.beatBytes) TransferSizes(1, max(mp.beatBytes, x.max)) else ourSupport
@@ -32,6 +31,13 @@ class TLAtomicAutomata(logical: Boolean = true, arithmetic: Boolean = true, conc
       val managers = edgeOut.manager.managers
       val beatBytes = edgeOut.manager.beatBytes
 
+      // This is necessary (though not sufficient) for correctness:
+      edgeOut.manager.findTreeViolation() match {
+        case None => ()
+        case Some(node) => require(edgeOut.manager.isTree, s"AtomicAutomata can only be placed infront of a tree of diplomatic nodes (${node.name} has parents ${node.inputs.map(_._1.name)})")
+      }
+      // You also need to know that the slaves don't have an internal masters that can get between the read and write
+
       // To which managers are we adding atomic support?
       val ourSupport = TransferSizes(1, edgeOut.manager.beatBytes)
       val managersNeedingHelp = managers.filter { m =>

src/main/scala/tilelink/Parameters.scala

@@ -67,6 +67,13 @@ case class TLManagerParameters(
       c = regionType >= RegionType.UNCACHED,
       a = supportsArithmetic && supportsLogical))
   }
+
+  def findTreeViolation() = nodePath.find {
+    case _: MixedAdapterNode[_, _, _, _, _, _, _, _] => false
+    case _: SinkNode[_, _, _, _, _] => false
+    case node => node.inputs.size != 1
+  }
+  def isTree = findTreeViolation() == None
 }
 
 case class TLManagerPortParameters(
@@ -170,6 +177,9 @@ case class TLManagerPortParameters(
   def supportsPutFullFast   (address: UInt, lgSize: UInt, range: Option[TransferSizes] = None) = supportHelper(false, _.supportsPutFull,    address, lgSize, range)
   def supportsPutPartialFast(address: UInt, lgSize: UInt, range: Option[TransferSizes] = None) = supportHelper(false, _.supportsPutPartial, address, lgSize, range)
   def supportsHintFast      (address: UInt, lgSize: UInt, range: Option[TransferSizes] = None) = supportHelper(false, _.supportsHint,       address, lgSize, range)
+
+  def findTreeViolation() = managers.flatMap(_.findTreeViolation()).headOption
+  def isTree = !managers.exists(!_.isTree)
 }
 
 case class TLClientParameters(
@@ -208,7 +218,6 @@ case class TLClientParameters(
 
 case class TLClientPortParameters(
   clients:       Seq[TLClientParameters],
-  unsafeAtomics: Boolean = false,
   minLatency:    Int = 0) // Only applies to B=>C
 {
   require (!clients.isEmpty)

src/main/scala/tilelink/ToAHB.scala

@@ -11,7 +11,7 @@ import scala.math.{min, max}
 import AHBParameters._
 
 case class TLToAHBNode()(implicit valName: ValName) extends MixedAdapterNode(TLImp, AHBImp)(
-  dFn = { case TLClientPortParameters(clients, unsafeAtomics, minLatency) =>
+  dFn = { case TLClientPortParameters(clients, minLatency) =>
     val masters = clients.map { case c => AHBMasterParameters(name = c.name, nodePath = c.nodePath) }
     AHBMasterPortParameters(masters)
   },

src/main/scala/tilelink/ToAPB.scala

@@ -10,7 +10,7 @@ import scala.math.{min, max}
 import APBParameters._
 
 case class TLToAPBNode()(implicit valName: ValName) extends MixedAdapterNode(TLImp, APBImp)(
-  dFn = { case TLClientPortParameters(clients, unsafeAtomics, minLatency) =>
+  dFn = { case TLClientPortParameters(clients, minLatency) =>
     val masters = clients.map { case c => APBMasterParameters(name = c.name, nodePath = c.nodePath) }
     APBMasterPortParameters(masters)
   },

src/main/scala/tilelink/Xbar.scala

@@ -34,8 +34,6 @@ class TLXbar(policy: TLArbiter.Policy = TLArbiter.roundRobin)(implicit p: Parame
     numClientPorts  = 1 to 999,
     numManagerPorts = 1 to 999,
     clientFn  = { seq =>
-      require (!seq.exists(_.unsafeAtomics) || seq.size == 1,
-        "An unsafe atomic port can not be combined with any other!")
       seq(0).copy(
         minLatency = seq.map(_.minLatency).min,
         clients = (TLXbar.mapInputIds(seq) zip seq) flatMap { case (range, port) =>