Working branching.

src/main/scala/IFBarrier.scala

@@ -11,6 +11,7 @@ class IFBarrier extends MultiIOModule {
       val instructionIn = Input(new Instruction)
       val instructionOut = Output(new Instruction)
       val stall = Input(Bool())
+      val flush = Input(Bool())
     })
 
   val PC = RegInit(UInt(32.W), 0.U)
@@ -19,11 +20,22 @@ class IFBarrier extends MultiIOModule {
 
   val instruction = Reg(new Instruction)
   val replay = RegInit(Bool(), false.B)
+  val flushRemaining = RegInit(UInt(2.W), 0.U)
+  flushRemaining := Mux(
+    io.flush,
+    2.U,
+    Mux(
+      flushRemaining === 0.U,
+      0.U,
+      flushRemaining - 1.U
+    )
+  )
+
   replay := io.stall
   instruction := io.instructionIn
 
   io.instructionOut := Mux(
-    io.stall,
+    io.stall || io.flush || flushRemaining > 0.U,
     Instruction.NOP,
     Mux(
       replay,