From 8d0f7781de05817b2a60e06c7ef4a35b70e3153d Mon Sep 17 00:00:00 2001
From: Dolu1990 <charles.papon.90@gmail.com>
Date: Tue, 17 May 2022 15:27:31 +0200
Subject: [PATCH] Fix DYNAMIC_TARGET from triggering fetch missprediction while
 in debug mode #254

---
 src/main/scala/vexriscv/plugin/BranchPlugin.scala | 7 +++++++
 src/main/scala/vexriscv/plugin/DebugPlugin.scala  | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/src/main/scala/vexriscv/plugin/BranchPlugin.scala b/src/main/scala/vexriscv/plugin/BranchPlugin.scala
index eb4c8d0..24d42fa 100644
--- a/src/main/scala/vexriscv/plugin/BranchPlugin.scala
+++ b/src/main/scala/vexriscv/plugin/BranchPlugin.scala
@@ -46,6 +46,7 @@ case class FetchPredictionBus(stage : Stage) extends Bundle {
 trait PredictionInterface{
   def askFetchPrediction() : FetchPredictionBus
   def askDecodePrediction() : DecodePredictionBus
+  def inDebugNoFetch() : Unit
 }
 
 
@@ -68,6 +69,7 @@ class BranchPlugin(earlyBranch : Boolean,
   var jumpInterface : Flow[UInt] = null
   var predictionExceptionPort : Flow[ExceptionCause] = null
   var branchExceptionPort : Flow[ExceptionCause] = null
+  var inDebugNoFetchFlag : Bool = null
 
 
   var decodePrediction : DecodePredictionBus = null
@@ -84,6 +86,9 @@ class BranchPlugin(earlyBranch : Boolean,
     decodePrediction
   }
 
+
+  override def inDebugNoFetch(): Unit = inDebugNoFetchFlag := True
+
   def hasHazardOnBranch = if(earlyBranch) pipeline.service(classOf[HazardService]).hazardOnExecuteRS else False
 
   override def setup(pipeline: VexRiscv): Unit = {
@@ -147,6 +152,7 @@ class BranchPlugin(earlyBranch : Boolean,
       val exceptionService = pipeline.service(classOf[ExceptionService])
       branchExceptionPort = exceptionService.newExceptionPort(branchStage)
     }
+    inDebugNoFetchFlag = False.setCompositeName(this, "inDebugNoFetchFlag")
   }
 
   override def build(pipeline: VexRiscv): Unit = {
@@ -353,6 +359,7 @@ class BranchPlugin(earlyBranch : Boolean,
       import branchStage._
 
       val predictionMissmatch = fetchPrediction.cmd.hadBranch =/= input(BRANCH_DO) || (input(BRANCH_DO) && input(TARGET_MISSMATCH))
+      when(inDebugNoFetchFlag) { predictionMissmatch := input(BRANCH_DO)}
       fetchPrediction.rsp.wasRight := ! predictionMissmatch
       fetchPrediction.rsp.finalPc := input(BRANCH_CALC)
       fetchPrediction.rsp.sourceLastWord := {
diff --git a/src/main/scala/vexriscv/plugin/DebugPlugin.scala b/src/main/scala/vexriscv/plugin/DebugPlugin.scala
index a0b4619..01c2acd 100644
--- a/src/main/scala/vexriscv/plugin/DebugPlugin.scala
+++ b/src/main/scala/vexriscv/plugin/DebugPlugin.scala
@@ -342,6 +342,10 @@ class DebugPlugin(var debugClockDomain : ClockDomain, hardwareBreakpointCount :
           case p : PrivilegeService => p.forceMachine()
           case _ =>
         }
+        pipeline.plugins.foreach{
+          case p : PredictionInterface => p.inDebugNoFetch()
+          case _ =>
+        }
         if(pipeline.things.contains(DEBUG_BYPASS_CACHE)) pipeline(DEBUG_BYPASS_CACHE) := True
       }
       when(allowEBreak) {